Authors

Jeong Won Shim, Jungho Kim, Neung Hwan Yim, Youngsoo Kim, and Yoon Young Kim

Title

Multi-objective Optimization of 1-DOF Transformable Wheel Mechanisms for High Adaptability

Conference

WCCM-APCOM 2022

Vol/No

PP

Year/Month

2022-08

Link

https://www.wccm2022.org/

Abstract

A transformable wheel is a critical mechanical component in a mobile robot climbing up or down step obstacles of various heights. In the case of a three-segmented transformable wheel to be considered here, it changes the effective radius and tilting angle of the legs for stable locomotion possibly with high energy efficiency. This study presents a multi-objective kinematic profile optimization of a one-degree-of-freedom (1-DOF) transformable wheel mechanism for highly adaptive locomotion. Compared with available 2-DOF wheel mechanisms [1, 2], a 1-DOF wheel mechanism has critical advantages in cost, weight, and actuator control. If 1-DOF wheels are designed for a step obstacle of specific geometry, however, they cannot be directly used for other step obstacles of different widths and heights because they do not have sufficient DOFs. To address this critical issue, we propose to employ the initial angle of contact between the wheel and a step as a new additional variable. We show that this idea enables us to establish a one-to-one mapping between configurations of the wheel shapes and the target obstacles of any geometry. Here, the initial contact angle is defined as the pre-rotated angle at the moment of the climbing. By using 1-DOF to transform the wheel and an additional variable of the initial contact angle, the transformable wheel can overcome various obstacles. However, the 1-DOF mechanism cannot represent all deformation shape because the profile of radius and angle are co-related unless the wheel is so transformed to follow an elaborate locomotion planning. This planning problem can be set up as an optimization problem where the wheel acceleration is minimized, and its instability is maximized for adaptive step-climbing. We employ the nondominated sorting genetic algorithm-II (NSGA-II) [3] to identify a Pareto-optimal front and examine the trade-off relation between performance indices. In order to analyze and design the movement of the transformable wheel, we use a simplified forward kinematics model. Finally, we present the 1-DOF optimal profiles utilizing a successfully configured Pareto-optimal front. The experiment results using an actual robot platform will be demonstrated.

Authors

Jeonghan Yu, Seok Won Kang, and Yoon Young Kim

Title

Novel Design of Adaptive and Efficient Knee Exoskeletons by Mechanism Topology Optimization Method

Conference

WCCM-APCOM 2022

Vol/No

PP

Year/Month

2022-08

Link

https://www.wccm2022.org/

Abstract

Knee joint exoskeletons play a critical role in assisting the movement of disabled and non-disabled humans. These wearable knee exoskeletons should generate sophisticated movement due to rather complicated knee joint motions and also interact safely with their wearers. Therefore, the designed knee exoskeletons should be adaptive to make them universally useful for humans of different body shapes [1]. Lightweight and cost-effectiveness are also other design considerations for the knee exoskeletons. However, because of several design requirements to consider, it is difficult or sometimes impossible to devise such knee exoskeletons even with many trials and errors. To overcome these difficulties, we present a novel design method to synthesize self-aligning and actuation-efficient knee exoskeleton mechanisms without any baseline design, a method similar to the structural topology optimization method.

The knee exoskeleton mechanism to be designed here is not just supposed to follow a specific path but to generate a desired knee instant center of rotation workspace. Furthermore, it should possess self-aligning capability by which undesirable force should not be applied to the human joint and also possibly yield the desired profile of mechanical advantage during gait motion. Here, we employ the ground model applied to the mechanism topology optimization method [2-3], which can represent any two-dimensional linkage mechanism possibly consisting of rigid links and revolute and prismatic joints. Moreover, we develop a new optimization-based formulation to achieve our design objectives. A few numerical results that validate our approach will be presented, along with a fabricated 3D-printed mock-up. Finally, the simulated actuation torque-speed curve using the designed exoskeleton confirms that the synthesized mechanism is safe and comfortable to wear and requires relatively low-powered actuation.

Authors

Neung Hwan Yim, Jungho Kim, Jeong Won Shim, Youngsoo Kim, and Yoon Young Kim

Title

Optimization-based synthesis of 1-DOF underactuated spring-linkage mechanism

Conference

WCCM-APCOM 2022

Vol/No

PP

Year/Month

2022-08

Link

https://www.wccm2022.org/

Abstract

For a mechanism to be adaptive in a two-dimensional plane, it must have more than one-degree- of-freedom (DOF). For example, a 1-DOF fully actuated mechanism having a single actuator can only follow a specific path. On the other hand, a single actuator-driven 1-DOF underactuated spring-linkage mechanism can adaptively follow a target path blocked by an obstacle via the deformations of spring elements [1, 2]. The simultaneous use of deformable spring elements and rigid links embodies the adaptability of an underactuated mechanism operating in a two- dimensional plane. The working principle of the underactuated spring-linkage mechanism is as follows; a 1-DOF underactuated spring-linkage mechanism can generate a specific path that minimizes the entire mechanism spring energy if no obstacle is present while it can go through significant elastic deformations to overcome an obstacle if there is any. The question is how to configure spring elements for a selected baseline rigid-link mechanism and determine their specific dimensions. Because one cannot pre-determine the number of spring elements to be used, it is inefficient and cumbersome to repeat many dimensional syntheses of spring elements by trying different numbers and configurations of spring elements. To be able to perform a streamlined synthesis of spring elements without many trials and errors, we propose a new optimization-based synthesis method, similar to the mechanism topology optimization [3, 4]. While earlier studies [3, 4] considered the synthesis of a rigid-link mechanism (without spring elements) only, our approach synthesizes spring configurations in an underactuated spring-linkage mechanism. In this respect, this work has newly performed the synthesis of spring configurations in underactuated spring- linkage mechanisms. The details of the proposed method, from formulation, analysis, to optimization, will be presented here. We will also show some numerical examples, such as the design of adaptive gait mechanisms and grippers, to demonstrate the validity and effectiveness of the proposed optimization-based synthesis method.

Authors

Jungho Kim, Jeong Won Shim, Youngsoo Kim, and Yon Young Kim

Title

Mechanism Synthesis of 1-DOF Transformable Wheel Structure Based on Kinematic Simulation and Topology Optimization Method

Conference

WCCM-APCOM 2022

Vol/No

PP

Year/Month

2022-08

Link

https://www.wccm2022.org/

Abstract

adaptively overcomes obstacles by modifying the shape of the wheel when it encounters various-sized obstacles [1]. So far, the adaptive motion was mainly generated by multi degree-of-freedom (DOF) mechanisms [2]. However, the operating cost of the multi-DOF mechanism is high because of structural complexity and many actuators. To overcome this limitation, we propose designing a 1-DOF wheel mechanism generating adaptive motion. However, it is complicated to identify a climbing strategy based on 1-DOF motion, and it is further challenging to synthesize 1-DOF mechanism that satisfies the target kinematics because there are no mechanism candidates based on the adaptive climbing strategy. Here, we 1) present a forward kinematics-based simulation model to establish adaptive wheel-climbing strategies and 2) propose a topology optimization method for synthesizing mechanisms that generates the target kinematics so that the wheel structure can successfully climb indoor-sized steps. First, a kinematic analysis model was developed to identify the target movement of the end-effector of the wheel to climb obstacles of various heights. Then, we propose a topology optimization-based synthesis method for 1-DOF transformable wheel mechanism to autonomously design the wheel structure. For the synthesis, we employ the topology optimization ground structure model which consists of zero-length springs and rigid blocks, called the JBM (joint-element connection rigid block model) because the model allows us to find an appropriate mechanism without starting with any baseline candidate mechanism [3]. Besides, for reducing complexity, we design the joint composition of the planar linkage mechanism by taking advantage of springs and blocks-based ground structure model. By using the developed method, novel transformable wheel mechanisms were successfully synthesized, and the kinematic and configuration characteristics of the designed mechanisms were investigated.

Authors

Neung Hwan Yim, Jeonghan Yu, Jungho Kim, Seok Won Kang, Yoon Young Kim

Title

Why are spring-connected block models useful for topology optimization of rigid-body linkage mechanisms?

Conference

ACSMO 2022

Vol/No

PP

Year/Month

Link

Abstract

Authors

Shin Young Kim, Yu Bin Oh, Joong Seok Lee, Yoon Young Kim

Title

Optimization design of strip-type metagratings for the simultaneous realization of mode-conversion and anomalous reflection of elastic waves

Conference

ACSMO 2022

Vol/No

PP

Year/Month

2022-05

Link

Abstract

Authors

Shin Young Kim, Woorim Lee, Joong Seok Lee, and Yoon Young Kim

Title

Beam-type Elastic Metagratings for Selective Reflections of Longitudinal Waves

Conference

The 11th International Conference on Metamaterials, Photonic Crystals and Plasmonics (META 2021)

Vol/No

PP

Year/Month

2021-07

Link

Abstract

Authors

Joong Seok Lee, Byungseong Ahn, Hyuk Lee and Yoon Young Kim

Title

Topology Optimization Design of Metamaterials for Anomalous Reflection of Elastic Waves

Conference

The 14th World Congress of in Computational Mechanics(WCCM) and ECCOMAS 2020 (WCCM-ECCOMAS 2020)

Vol/No

PP

Year/Month

2021-01

Link

wccm-eccomas2020.org

Abstract

Authors

Won Uk Yoon and Yoon Young Kim, Jun Hyeong Park, and Joong Seok Lee

Title

Design of Rigid Inclusions in Porous Materials for Total Sound Absorption Using Topology Optimization Method

Conference

ACSMO 2020

Vol/No

PP

Year/Month

2020-11

Link

Abstract

Authors

Jaemin Jeon, Jaeyong Kim, JongJun Lee, Yoon Young Kim, and Dongil Shin

Title

Development of a Surrogate Higher-order Box Beam Joint Model Using Deep Learning

Conference

ACSMO 2020

Vol/No

PP

Year/Month

2020-11

Link

Abstract

Authors

Jaemin Jeon, Dongil Shin, Jaeyong Kim, Jongjun Lee and Yoon Young Kim

Title

Deep Neural Network Approach to Construct General Box Beam Joint Stiffness for Higher-order Beam

Conference

Proceedings of APCOM 2019 (7th Asian Pacific Congress on Computational Mechanics)

Vol/No

PP

Year/Month

2019-12

Link

Abstract

Authors

Jaeyong Kim, Soomin Choi(ERC), Gang-Won Jang(세종대) and Yoon Young Kim

Title

Cross-section Analysis of General Thin-walled Beams for Higher-order Beam Theory

Conference

Proceedings of APCOM 2019 (7th Asian Pacific Congress on Computational Mechanics)

Vol/No

PP

Year/Month

2019-12

Link

Abstract

Authors

H. Lee(기계연), J. K. Lee, H. M. Seung(표준연), and Y. Y. Kim

Title

Refracting/Reflecting ultrasonic waves by sub-wavelength elastic metasurfaces

Conference

Proceedings of 5th International Conference on Materials and Reliability

Vol/No

PP

Year/Month

2019-11

Link

Abstract

Authors

Dongil Shin, Yoon Young Kim

Title

Data-driven Shape Functions for Higher-order Beam Finite Element Analysis of Thin-walled Composite Beams

Conference

USNCCM 15

Vol/No

PP

Year/Month

2019-07

Link

Abstract

Authors

Jeonghan Yu, Sang Min Han, Yoon Young Kim

Title

Path Generation of Planar Linkage Mechanisms by Simultaneous Shape and Topology Optimization Based on the Spring-connected Rigid Block Model

Conference

WSCMO 13

Vol/No

PP

Year/Month

2019-05

Link

Abstract

Authors

Neung Hwan Yim, Yoon Young Kim

Title

Topology optimization of linkage mechanism by big data approach

Conference

WCSMO 13

Vol/No

PP

Year/Month

2019-05

Link

Abstract

The aim of this study is to investigate if a big data approach can effectively handle linkage mechanism problems which are otherwise difficult to solve by a gradient-based topology optimization. Typical gradient-based topology optimization for mechanism synthesis can determine the topology and dimension of mechanisms producing the target path at the mechanism end-effector. But in this case, its end-effector location should be known or pre-determined. In case the end-effector location is not pre-known, we many consider a numerous number of randomly chosen different candidate locations of the end-effector and perform the repetitive topology optimization. Because the mechanism may not generate a desired target path if the end-effector location is wrongly designated, we need to develop a new topology optimization method to design a linkage mechanism that generated path by allowing the end-effector to be placed at desired location. As an efficient way of mechanism synthesis without predetermined end-effector locations, our strategy is to combine the artificial intelligence algorithm based on big data and a numerically efficient gradient-based approach.

In this study, the design domain is discretized by the spring-connected rigid block model. The spring stiffness values are varied as functions of the design variables and their values can be used to determine the layout of a synthesized mechanism by the topology optimization. The objective is to find a mechanism yielding a desired path at the end-effector of a synthesized mechanism. In the present method, we first identify the location of the candidate end-effector and the topology of a linkage mechanism by a deep neural network which is constructed from big data obtained with various end-effector locations and spring stiffness values. Although the candidate end-effector location and the mechanism topology are determined at this first stage, the detailed dimensions of the mechanism are not known. Accordingly, the nest step is to perform a dimensional synthesis using a gradient-based optimizer to find a specific mechanism using the results obtained in the first stage. We will demonstrate the effectiveness of the present approach in terms of

Authors

Dongil Shin, Yoon Young Kim

Title

Higher-order Beam Analysis Using Big Data

Conference

KSCM-GACM International Workshop

Vol/No

PP

Year/Month

2018-10

Link

Abstract

Authors

Neunghwan Yim, Seok-Won Kang, Yoon Young Kim

Title

Synthesis of Gear-Linkage Mechanisms by Topology Optimization

Conference

2018 IDETC/CIE (International Design Engineering Technical Conferences & Computers and Information in Engineering Conference)

Vol/No

PP

Year/Month

2018-08

Link

Abstract

Authors

Dongil Shin and Yoon Young Kim

Title

Thin-walled beam analysis based on higher-order beam theory using cross-sectional deformations identified by principal component analysis

Conference

ETME 2018

Vol/No

PP

Year/Month

2018-08

Link

Abstract

Authors

Joshua Minwoo Kweun, Xiongwei Yang, and Yoon Young Kim

Title

Generating Multimodal Interference Using an Anisotropic Metamaterial Cavity to Achieve Various Elastic Wave Mode Conversion

Conference

ETME 2018

Vol/No

PP

Year/Month

2018-08

Link

Abstract

Authors

Hyuk Lee, Jun Kyu Lee, Hong Min Seung and Yoon Young Kim

Title

Fully-Transmissive Elastic Planar Metasurface: Anomalous wavefront control within subwavelength scale

Conference

ETME 2018

Vol/No

PP

Year/Month

2018-08

Link

Abstract

Authors

Yoon Young Kim

Title

Algorithm-Based Automated Synthesis of Linkage Mechanisms

Conference

ETME 2018

Vol/No

PP

Year/Month

2018-08

Link

Abstract

Authors

Xiongwei Yang, Joshua M. Kweun & Yoon Young Kim

Title

Perfect transmodal Fabry-Perot resonance interferometer: from theory to design and realization with anisotropic metamaterials

Conference

IUTAM Symposium on Acoustic/Elastic Metamaterials and Their Design and Applications

Vol/No

PP

Year/Month

June 5-9, 2018

Link

Abstract

Authors

Jeong Han Yu, Sang Min Han and Yoon Young Kim

Title

Simultaneous shape and topology optimization of planar linkage mechanisms based on the spring-connected rigid block model

Conference

ACSMO 2018

Vol/No

PP

Year/Month

2018.05.21-24

Link

Abstract

Authors

Yoon Young Kim and Xiongwei Yang

Title

Topology optimization of metamaterials for perfect transmodal fabry-perot interferometers

Conference

ACSMO 2018

Vol/No

PP

Year/Month

2018.05.21-24

Link

Abstract

Authors

D.M. KIM, S. Choi, G.-W. Jang and Y.Y. Kim

Title

Higher-Order Beam Theory (Hobt) Based Buckling Analysis for Thin-Walled Box Beams

Conference

Proceedings of CODE2018 (4th International Conference on Computational Design in Engineering)

Vol/No

PP

Year/Month

April 01-05, 2018

Link

Abstract

Authors

J. H. Oh, S. Qi, Y. Y. Kim and B. Assouar

Title

Elastic Metamaterial for Vibration Shielding at Broad Low Frequencies

Conference

Proceedings of 2017 ICU (International Congress on Ultrasonics)

Vol/No

PP

Year/Month

Dec. 18~20, 2017

Link

Abstract

Authors

Y. Y. Kim, J. M. Kweun and X. Yang

Title

Discovery of Transmodal Fabry-Perot Resonance for Elastic Wave Mode Conversion

Conference

Proceedings of 2017 ICU (International Congress on Ultrasonics)

Vol/No

PP

Year/Month

Dec. 18~20, 2017

Link

Abstract

Authors

Joong Seok Lee, Yoon Young Kim

Title

Metaporous Layers for Broadband Sound Absorption using Multiple Slow Waves has been accepted as ORAL presentation

Conference

SAPEM 2017

Vol/No

PP

Year/Month

2017-12

Link

Abstract

Authors

Dongil Shin, Soomin Choi, Gang-Won Jang, Yoon Young Kim

Title

Higher-order beam theory for the structural analysis of laminated composite thin-walled box beams

Conference

ICCS20

Vol/No

PP

Year/Month

2017-09

Link

Abstract

Authors

Joshua Minwoo Kweun, Xiongwei Yang, Yoon Young Kim

Title

Perfect Mode Conversion of Elastic Waves: Realization with Anisotropic Metamaterials

Conference

META 2017

Vol/No

PP

Year/Month

2017-07

Link

Abstract

Authors

Byungseong Ahn, Hyung Jin Lee, Yoon Young Kim

Title

Design of Anisotropic Metamaterials by Topology Optimization

Conference

META 2017

Vol/No

PP

Year/Month

2017-07

Link

Abstract

Authors

Hyuk Lee, Jun Kyu Lee, Hong Min Seung, Yoon Young Kim

Title

Elastic Metasurface for High Transmission Anomalous Beam Refraction

Conference

META 2017

Vol/No

PP

Year/Month

2017-07

Link

Abstract

Authors

Yoon Young Kim

Title

Extreme elastic anisotropy - realization by metamaterials

Conference

META 2017

Vol/No

PP

Year/Month

2017-07

Link

Abstract

Authors

Kiyean Kim, Hyung Jin Lee, Chung Il Park, Yoon Young Kim

Title

Transduction Efficiency Boosting by a Passive Resonator in Magnetostrictive Patch Transducer

Conference

QNDE 2017

Vol/No

PP

Year/Month

2017-07

Link

Abstract

Authors

Xiongwei Yang, Joshua Minwoo Kweun, Yoon Young Kim

Title

Transmodal Fabry-Perot Resonance using Anisotropic Elastic Metamaterials

Conference

Phononics 2017

Vol/No

PP

Year/Month

2017-06

Link

Abstract

Authors

Yoon Young Kim, Suh In Kim, Yong-Sub Yi, Joonhong Park

Title

Topology and Shape Optimization for a New Concept Vehicle Suspension Mechanism

Conference

WCSMO-12

Vol/No

PP

Year/Month

2017-06

Link

Abstract

Authors

Seok Won Kang, Jeong Han Yu, Sang Min Han, Yoon Young Kim

Title

Topology optimization of general-joint planar linkage mechanisms with an application to finger rehabilitation device design

Conference

WCSMO-12

Vol/No

PP

Year/Month

2017-06

Link

Abstract

Authors

Byungseong Ahn, Hyung Jin Lee, Yoon Young Kim

Title

Topology Optimization of Anisotropic Metamaterials to Realize the Desired EFC and Field Polarization

Conference

WCSMO-12

Vol/No

PP

Year/Month

2017-06

Link

Abstract

Authors

Neung Hwan Yim, Seok Won Kang, Yoon Young Kim

Title

Topology optimization of planar linkage mechanisms involving gear componenets

Conference

WCSMO-12

Vol/No

PP

Year/Month

2017-06

Link

Abstract

Authors

Jun Hyeong Park, Hyung Jin Lee, Yoon Young Kim

Title

Characterization of anisotropic acoustic metamaterials

Conference

Internoise 2016

Vol/No

PP

Year/Month

2016-08

Link

Abstract

Authors

Hyuk Lee, Joo Hwan Oh, Hong Min Seung, Seung Hyun Cho, Yoon Young Kim

Title

Total transmission super-resolution imaging with a hyperbolic elastic metamaterial

Conference

META 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Yoon Young Kim

Title

Numerical Synthesis of Linkage Mechanisms by Topology Optimization

Conference

WCCM & APCOM 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Dongil Shin, Soomin Choi, Gang-Won Jang, Yoon Young Kim

Title

Finite Element Beam Analysis of FRP Composite Thin-walled Box Beams by Using Higher-order Beam Theory

Conference

WCCM & APCOM 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Seong Jae Choi, Jun Kyu Lee, Joo Hwan Oh, Yoon Young Kim

Title

Extremely Low Frequency Bandpass Filtering by a Metamaterial Consisting of Discrete Elements

Conference

WCCM & APCOM 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Do-min Kim, Soomin Choi, Yoon Young Kim

Title

Buckling Analysis by Using Higher-order beam theory (HoBT)

Conference

WCCM & APCOM 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Jun Hyeong Park, Hyung Jin Lee, Yoon Young Kim

Title

Characterization method for anisotropic acoustic metamaterial slabs

Conference

WCCM & APCOM 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Jieun Yang, Joong Seok Lee, Yoon Young Kim

Title

Analysis and Design of a Metaporous Layer of High Sound Absorption

Conference

WCCM & APCOM 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Soomin Choi, Gang-Won Jang, Yoon Young Kim

Title

Higher-Order Beam-Based Ground Topology Optimization for Thin-Walled Box Beam Structures

Conference

WCCM & APCOM 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Xiong Wei Yang, Byengseong Ahn, Joong Seok Lee, Pyung Sik Ma, Hyung Jin Lee, Yoon Young Kim

Title

Topology Optimization of Anisotropic Metamaterials

Conference

WCCM & APCOM 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Joong Seok Lee, Elke Deckers, Stijn Jonckheere, Wim Desmet, Yoon Young Kim

Title

A Hybrid Finite Element - Wave Based Modelling Technique for the Analysis of 2D Sound Absorbing Biot's Poroelastic Materials

Conference

WCCM & APCOM 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Chung Il Park, Hong Min Seung, Jun Kyu Lee, Yoon Young Kim

Title

An Annular Array MPT for Enhanced Generation of Omnidirectional SH Waves in a Plate

Conference

QNDE 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Jun Kyu Lee, Hong Min Seung, Chung Il Park, Joo Kyung Lee, Do Hyeong Lim, Yoon Young Kim

Title

Torsional Vibration Transduction in a Solid Shaft by MPTs

Conference

QNDE 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Joshua M Kweun, Chenzhe Li, Yongping Zheng, Maenghyo Cho, Yoon Young Kim, Kyeongjae Cho

Title

Electronic structural relationship between bulk and surface of metal oxides for ultrafast catalysts screening

Conference

NanoKorea 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Hyuk Lee, Joo Hwan Oh, Hong Min Seung, Seung Hyun Cho, Yoon Young Kim

Title

Impedance matched elastic hyperbolic metamaterial lens for super-resolution imaging

Conference

NanoKorea 2016

Vol/No

PP

Year/Month

2016-07

Link

Abstract

Authors

Suh In Kim, Seok Won Kang, Sang Min Han, Yong-Sub Yi, Joonhong Park, and Yoon Young Kim

Title

Automated computational synthesis of suspension mechanisms – new design paradigm

Conference

chassis.tech plus 2016

Vol/No

PP

Year/Month

2016-06

Link

Abstract

Authors

Dongil Shin, Soomin Choi, Gang-Won Jang, Yoon Young Kim

Title

Analysis of thin-walled box beams with variable cross sections by the higher-order beam theory

Conference

ECCOMAS 2016

Vol/No

PP

Year/Month

2016-06

Link

Abstract

Authors

Do-Min Kim, Soomin Choi, Gang-Won Jang, Yoon Young Kim

Title

Buckling analysis of thin-walled box beam-columns by higher-order beam theory (HoBT)

Conference

ECCOMAS 2016

Vol/No

PP

Year/Month

2016-06

Link

Abstract

Dongil Shin*, Soomin Choi, Gang-Won Jang, Yoon Young Kim,“Analysis of thin-walled box beams with variable cross sections by the higher-order beam theory", Proceedings of ECCOMAS 2016 (Jun 5–10, 2016, Crete, Greece) 발표일6.7

Authors

Soomin Choi, Yoon Young Kim

Title

Higher-order beam analysis of multiply-connected box beams under out-of-plane bending and torsion using exact joint matching conditions

Conference

ECCOMAS 2016

Vol/No

PP

Year/Month

2016-06

Link

Abstract

Authors

Xiong Wei Yang, Joong Seok Lee and Yoon Young Kim

Title

Bandgap-Maximizing Topology Optimization of Locally Resonant Elastic Metamaterials Using Effective Mass Density

Conference

ACSMO2016

Vol/No

PP

Year/Month

2016-05

Link

Abstract

Authors

Joong Seok Lee, Peter Göransson and Yoon Young Kim

Title

Design of interior space of a dissipative muffler by topology optimization to maximize sound attenuation performance

Conference

ACSMO2016

Vol/No

PP

Year/Month

2016-05

Link

Abstract

Authors

Won Wuk Yoon, Jun Hyeong Park, Joong Seok Lee and Yoon Young Kim

Title

Rigid partitioning in a porous layer for low-frequency sound absorption enhancement using topology optimization method

Conference

ACSMO2016

Vol/No

PP

Year/Month

2016-05

Link

Abstract

Authors

Sang Min Han, Suh In Kim and Yoon Young Kim

Title

Topology optimization of planar linkage mechanisms with target paths defined by Fourier descriptors

Conference

ACSMO2016

Vol/No

PP

Year/Month

2016-05

Link

Abstract

Authors

Jun Kyu Lee, Joo Kyung Lee, and Yoon Young Kim

Title

Effects of Magnetic Interferences in Magnetostrictive Patch Transducers on Ultrasonic Signals

Conference

QNDE 2015

Vol/No

PP

Year/Month

2015-07

Link

Abstract

Authors

Kiyean Kim, Hyung Jin Lee, Joo Kyung Lee, and Yoon Young Kim

Title

Eddy Current Circuit Design for Power Maximization of an Omnidirectional Magnetostrictive Patch Transducer

Conference

QNDE 2015

Vol/No

PP

Year/Month

2015-07

Link

Abstract

Authors

Hong Min Seung, Chung II Park, and Yoon Young Kim

Title

EMAT for Omni-Directional Shear-Horizontal Guided Wave Generation in a Plate

Conference

QNDE 2015

Vol/No

PP

Year/Month

2015-07

Link

Abstract

Authors

Jieun Yang, Joong Seok Lee and Yoon Young Kim

Title

Broadband Sound Absorption of a Metaporous Layer with Periodic Rigid Partitions

Conference

ICSV22

Vol/No

PP

Year/Month

2015-07

Link

Abstract

Authors

Seok Won Kang, Suh In Kim and Yoon Young Kim

Title

Topology Optimization of Planar Linkage Systems having Various Joint Types

Conference

WCSMO-11

Vol/No

PP

Year/Month

2015-06

Link

Abstract

Authors

Sung Kyu Kwak, Byungseong Ahn, Suh In Kim and Yoon Young Kim

Title

Simultaneous design of a loading location and structure by topology optimization

Conference

WCSMO-11

Vol/No

PP

Year/Month

2015-06

Link

Abstract

Authors

Yoon Young Kim, Suh In Kim, Byungseong Ahn, Seok Won Kang, Yong-Sub Yi and Joonhong Park

Title

Topology optimization of 3D suspension linkage system of an automobile by using work transmittance efficiency based mechanism synthesis formulation

Conference

WCSMO-11

Vol/No

PP

Year/Month

2015-06

Link

Abstract

Authors

Min Kyung Lee, Seong Jae Choi and Yoon Young Kim

Title

Elastic Cloaking Device for Dynamic Stress Mitigation

Conference

PHONONICS 2015

Vol/No

PP

Year/Month

2015-06

Link

Abstract

Authors

Hyung Jin Lee, Heung Son Lee, Pyung Sik Ma, Joo Kyung Lee and Yoon Young Kim

Title

Effective Material Parameter Retrieval of Anisotropic Elastic Metamaterials

Conference

PHONONICS 2015

Vol/No

PP

Year/Month

2015-06

Link

Abstract

Authors

Joo Hwan Oh, Young Eui Kwun, Hyung Jin Lee and Yoon Young Kim

Title

Metasolid for Independent Tuning of Negative Effective Density and Stiffness

Conference

PHONONICS 2015

Vol/No

PP

Year/Month

2015-06

Link

Abstract

Authors

Yoon Young Kim

Title

Advances in Magnetostrictive Patch Transducers for Ultrasonic Guided Wave Inspection

Conference

14th APCNDT 2013 Conference

Vol/No

PP

Year/Month

2013.11

Link

Abstract

Authors

Jieun Yang, Joong Seok Lee, Yoon Young Kim

Title

Enhancement of sound absorption by periodic partitions embedded in a hard-backed porous layer

Conference

SAPEM2014

Vol/No

PP

Year/Month

2014-12-16

Link

Abstract

Authors

Seong Yeol Choi, Il Kyu Lee, Yoon Young Kim

Title

Investigation on Different Types of Band Gap Interactions in Acoustic Metamaterials

Conference

ASME2014

Vol/No

PP

Year/Month

2014-11-14

Link

Abstract

Authors

Hyung Jin Lee, Yoon Young Kim

Title

Elastic Wave Mode Converters by Using Elastic Metamaterials Exhibiting Anomalous Polarizations

Conference

ASME2014

Vol/No

PP

Year/Month

2014-11-14

Link

Abstract

Authors

Joo Hwan Oh, Hong Min Seung, Young Kwan Ahn, Yoon Young Kim

Title

Mechanics of a Truly Hyperbolic Elastic Metamaterial Lens and Design Optimization

Conference

ASME2014

Vol/No

PP

Year/Month

2014-11-14

Link

Abstract

Authors

Sung Kyu Kwak, Suh In Kim, Byungseong Ahn, Sangmin Han and Yoon Young Kim

Title

Simultaneous Optimization of Loading point and Structural Topological Layouts for the Design of Loaded Frames

Conference

EngOpt 2014

Vol/No

PP

Year/Month

2014-09

Link

Abstract

Authors

Suh In Kim, Seok Won Kang and Yoon Young Kim

Title

Linkage mechanism synthesis by topology optimization

Conference

EngOpt2014

Vol/No

PP

Year/Month

2014-09

Link

Abstract

Authors

Minwoo Kweun, Yoon Young Kim, and Kyeongjae Cho

Title

High-throughput screening and design of Mullite family complex oxide catalysts via First principles calculation: Bulk & Surface relationship study

Conference

NANO KOREA 2014

Vol/No

PP

Year/Month

2014-07

Link

Abstract

Authors

Minwoo Kweun, Yongping Zheng, Chenzhe Li, Hanchul Kim, Yoon Young Kim, and Kyeongjae Cho

Title

High-throughput screening and design of Mullite family complex oxide catalysts via First principles calculation: Bulk-Surface relationship for high-throughput screening of metal oxide catalysts

Conference

ISGMA 2014

Vol/No

PP

Year/Month

2014-06

Link

Abstract

Authors

Minwoo Kweun, Chenzhe Li, Yongping Zheng, Kanghoon Yim, Seungwu Han, Yoon Young Kim, and Kyeongjae Cho

Title

High-throughput screening and design of Mullitefamily complex oxide catalysts via First principles calculation

Conference

247th ACS

Vol/No

PP

Year/Month

2014-03

Link

Abstract

Title: High-throughput screening and design of mullite family complex oxide catalysts via first principles calculation

Authors: Minwoo Kweun1, Chenzhe Li1, Yongping Zheng1, Kanghoon Yim2, Seungwu Han2, Yoon Young Kim1*, and Kyeongjae Cho1,3*

1 Department of Mechanical and Aerospace Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul 151-742, Republic of Korea

2 Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul 151-755, Republic of Korea

3 Department of Materials Science and Engineering and Department of Physics, University of Texas at Dallas, Richardson, TX, 75080, United States

*kjcho@utdallas.edu, yykim@snu.ac.kr

In the development of efficient clean energy systems, new functional materials are critically needed, and highly efficient catalysts based on earth-abundant materials are essential to overcome the limited supply of currently used precious metal catalysts based on platinum group metals (PGMs). From this point of view, design of proper catalysts in various energy systems is an important problem to accelerate the required new material development. For this purpose, we will apply a database search of earth-abundant complex oxides and first principles design to identify highly efficient catalyst candidates. The identified catalyst candidates will be synthesized and characterized for the validation of their designed catalytic functions.

We will demonstrate an efficient method to explore novel oxide catalyst candidates, particularly mullite-type structure family which is already shown have high activity in photocatalyst and catalytic converter of automobile. Specifically, Mn-mullite based on SmMn2O5 is shown to have 45% higher catalytic activity then Pt for NO oxidation in Diesel exhaust control application. Although there are novel theoretical approaches developed for transition metal catalysts, the identification of preferred catalytic activity of complex oxides is hard to achieve in short time for the various surface preference and diverse reaction precursors and scenarios. As the first step in design method development, we will investigate the bulk properties of the target catalyst materials, Schafarzikite (MX2O4; M=Pb4+, Sn4+, X=Pb2+; or M=Mn2+, Fe2+, Co2+, Ni2+, Zn2+, Mg2+, X=Sb3+, As3+) and its derivatives which is the highest symmetry group of mullite-type family. Different oxidation states of transition metal (M=Mn2+, Fe2+) in Schafarzikite are expected to provide different catalytic activity from those of Mn-mullites, SmMn2O5 with Mn3+, Mn4+. Subsequently, we will explore broader mullite family oxides (e.g., Apuanite, Versilaite, etc.) and conduct high-throughput screening to identify catalyst candidates for different energy system applications including metal-air batteries, fuel cells, catalytic converters, and photocatalysts.

1. Wang, W.; McCool, G.; Kapur, N.; Yuan, G.; Shan, B.; Nguyen, M.; Graham, U.; Davis, B.; Jacobs, G.; Cho, K.; Hao, X., Mixed-phase oxide catalyst based on Mn-mullite (Sm, Gd)Mn2O5 for NO oxidation in diesel exhaust. Science 2012, 337 (6096), 832-835.

Authors

Yoon Young Kim, Do-Min Kim, Suh In Kim, Soomin Choi and Gang-Won Jang

Title

Topology optimization of Thin-walled beam sructures

Conference

WCCM XI

Vol/No

PP

Year/Month

2014-07

Link

Abstract

Authors

Hong Min Seung, Yoon Young Kim

Title

Omni-Directional Shear-Horizontal Wave Magnetostrictive Patch Transducer for the Inspection of a Ferromagnetic Plate

Conference

QNDE 2014

Vol/No

PP

Year/Month

2014-07

Link

Abstract

Authors

Joo Kyung Lee, Yoon Young Kim

Title

Single-Mode Omni-Directional Lamb Wave Generation by Magnetostrictive and Electromagnetic Acoustic Transducers

Conference

QNDE 2014

Vol/No

PP

Year/Month

2014-07

Link

Abstract

Authors

Heung Son Lee, Yoon Young Kim

Title

The Green’s Function for Guided Waves in a Three-Dimensional Elastic Plate

Conference

QNDE 2014

Vol/No

PP

Year/Month

2014-07

Link

Abstract

Authors

Suh In Kim, Yoon Young Kim

Title

Simultaneous Type and Number Synthesis of Planar Linkage Mechanisms

Conference

IMSD2014-ACMD2014

Vol/No

PP

Year/Month

2014-07

Link

Abstract

Authors

Byungseong Ahn, Suh In Kim, Yoon Young Kim

Title

Eigenvalue problems for layout/topology optimization of multi-component systems

Conference

CJK-OSM8

Vol/No

PP

Year/Month

2014-05

Link

Abstract

Authors

Suh In Kim, Yoon Young Kim

Title

Topology optimization of planar linkage mechanisms: Modeling and Special Post-processing Issues

Conference

CJK-OSM8

Vol/No

PP

Year/Month

2014-05

Link

Abstract

Authors

Yoon Young Kim, Suh In Kim

Title

Topology optimization of planar linkage mechanisms: Why is energy-based formulation effective?

Conference

CJK-OSM8

Vol/No

PP

Year/Month

2014-05

Link

Abstract

Authors

Sung Kyu Kwak, Suh In Kim, Byungseong Ahn, Yoon Young Kim

Title

Simultaneous design of a loading point and a structure by topology optimization

Conference

CJK-OSM8

Vol/No

PP

Year/Month

2014-05

Link

Abstract

Authors

Pyung Sik Ma, Hyung Jin Lee, and Yoon Young Kim

Title

Topology Design of Metamaterials for Wave Tailoring in Elastic Waveguides

Conference

CJK-OSM8

Vol/No

PP

Year/Month

2014-05

Link

Abstract

Authors

Joo Hwan Oh, Young Kwan Ahn, and Yoon Young Kim

Title

Topology Optimization of Hyperbolic Elastic Metamaterials for Sub-wavelength Resolution

Conference

CJK-OSM8

Vol/No

PP

Year/Month

2014-05

Link

Abstract

Authors

Yoon Young Kim, Joo Hwan Oh and Hong Min Seung

Title

Elastic metamaterial hyperlens exhibiting hyperbolic equi-frequency contours

Conference

META 2014

Vol/No

PP

Year/Month

2014-05 Singapore

Link

Abstract

Authors

Yoon Young Kim, Kyung Ho Sun, and Joo Hwan Oh

Title

Modeling of Magnetostrictive Patch Transducers for Guided Wave Simulation in a Plate

Conference

APCOM & ISCM 2013

Vol/No

PP

Year/Month

2013-12 Singapore

Link

Abstract

Authors

Joong Seok Lee, Peter Göransson, and Yoon Young Kim

Title

Design of Reactive and Dissipative Materials Distribution in Silencer by using Topology Optimization

Conference

APCOM & ISCM 2013

Vol/No

PP

Year/Month

2013-12 Singapore

Link

Abstract

Authors

Do-min Kim, Suh In Kim, Soomin Choi, Gang-Won Jang, and Yoon Young Kim

Title

Topology optimization based on the higher-order beam theory for automobile body frame design

Conference

APCOM & ISCM 2013

Vol/No

PP

Year/Month

2013-12 Singapore

Link

Abstract

Authors

Chulmin Cho, Hansol Yoon, Heonjun Yoon, Hongjin Kim, Sowon Lee, Byeng D. Youn, Jae Eun Kim, and Yoon Young Kim

Title

Harvestable Energy Analysis for Visualization of Harvestable Energy

Conference

The 7th World Congress on Biomimetics, Artificial Muscles and Nano-Bio(BAMN2013)

Vol/No

PP

Year/Month

2013.8 (Jeju, Korea)

Link

Abstract

Energy harvesting is the process by which energy is captured from external energy sources (e.g., mechanical vibration, temperature difference), transduced, and stored for power supply to small, wireless devices. It is important to select an optimal site for energy harvesting and design an energy harvester for maximum energy harvesting. Harvestable energy has to be measured for the optimal site selection. This study aims at proposing energy harvesting analysis that visualizes harvestable energy in response to vibration and thermal energy sources. This is a preliminary study of harvestable energy scanner, which enables an optimal site determination for energy harvesting. This technique offers many benefits: (a) first-hand inspection of available and harvestable energy, (b) preliminary analysis of energy conversion, and (c) optimal selection of harvester and wireless device types. The three-fold steps are proposed to build an energy map: (1) data acquisition from ambient energy sources, (2) harvestable energy analysis with energy conversion models, and (3) visualization of harvestable energy. A small-scale power plant was used for demonstration of the proposed idea.

Authors

Hong Min Seung and Yoon Young Kim

Title

How to Generate Omni-Directional Shear-Horizontal Waves in Plates?

Conference

QNDE 2013

Vol/No

PP

Year/Month

2013-07, Baltimore, Maryland, USA

Link

Abstract

Authors

Ki Yean Kim, Young Eui Kwon, and Yoon Young Kim

Title

Inspection of a Part Circumferential Notch in a Pipe by Torsional Waves: Simulations and Experiments

Conference

QNDE 2013

Vol/No

PP

Year/Month

2013-07, Baltimore, Maryland, USA

Link

Abstract

Authors

Yoon Young Kim and Joo Kyung Lee

Title

Principle of Omni-Directional Lamb Wave Generation by Magnetostrictive Patch Transducer

Conference

QNDE 2013

Vol/No

PP

Year/Month

2013-07, Baltimore, Maryland, USA

Link

Abstract

Authors

Yoon Young Kim, Joo Hwan Oh, Pyung Sik Ma, Hyung Jin Lee, Min Kyung Lee, Il Kyu Lee, and Hoe Woong Kim

Title

Experimental techniques for ultrasonic metamaterials with guided waves

Conference

Phononics 2013

Vol/No

PP

Year/Month

2013-06 Sharm El-Sheikh, Egypt

Link

Abstract

Authors

Pyung Sik Ma, Young Eui Kwon, and Yoon Young Kim

Title

Phononic crystal tailoring for single-mode ultrasonic wave excitation

Conference

Phononics 2013

Vol/No

PP

Year/Month

2013-06 Sharm El-Sheikh, Egypt

Link

Abstract

Authors

Jun Hyeong Park, Young Kwan Ahn, Pyung Sik Ma, Joo Hwan Oh, and Yoon Young Kim

Title

Engineering of phononic crystals by topology optimization

Conference

Phononics 2013

Vol/No

PP

Year/Month

2013-06 Sharm El-Sheikh, Egypt

Link

Abstract

Authors

Suh In Kim and Yoon Young Kim

Title

Ground structure based linkage mechanism topology optimization: new formulation and applicatiosn including automobile steering system design

Conference

WCSMO-10

Vol/No

PP

Year/Month

2013-05 Orlando, Florida, USA

Link

Abstract

Authors

Jun Hyeong Park, Pyung Sik Ma and Yoon Young Kim

Title

Topology optimization of phononic cyrstals for self-collimation of elastic waves

Conference

WCSMO-10

Vol/No

PP

Year/Month

2013-05 Orlando, Florida, USA

Link

Abstract

Authors

Yoon Young Kim, Eun Il Kim and Byeongseong Ahn

Title

The use of topology optimization for artistic image generation

Conference

WCSMO-10

Vol/No

PP

Year/Month

2013-05 Orlando, Florida, USA

Link

Abstract

Authors

Soomin Choi, Gang Won Jang and Yoon Young Kim

Title

Joint Modeling Issues in Simplified Beam-Plate Body Analysis

Conference

SAE 2013 World Congress

Vol/No

PP

Year/Month

2013-04 Detroit, Michigan, USA

Link

Abstract

Exact Matching Conditions at a Joint of Thin-Walled Box Beams under Out-of-Plane Loadings and In-Plane Loadings.

With the increasing customer demands, design engineers steadily face new complex design issues, but the time allowed to solve those issues is not enough and even getting shorter with the competitive nature of the automotive market. As a result, a fundamental change in design process is required, and the “Analysis Leads Design” process receives attention. Especially in the design of automobile bodies, a fast, efficient design strategy is to employ a “simplified beam-plate model” that possibly captures the underlying mechanics of vehicle bodies consisting of a number of thin-walled beams and plates. The simplified beam-plate model can be effectively used in the early stage of concept design to improve various performance attributes such as stiffness, NVH, etc. because detailed CAD information is not required to carry out FE analysis.

However, the simplified beam-plate model that has been so far developed cannot accurately represent correct structural responses of automobile bodies, predicting much stiffer responses than the detailed FE model does. The prediction of stiff responses is mainly due to the ignorance of local deformations around joint part which is occurred in actual thin-walled closed beam. There have been many efforts to improve the errors of analysis such as treating joint part as an artificial spring, but those were not able to uniformly represent the correct joint flexibility.

It should be noted that cross-sectional deformations such as warping and distortion are accompanied when thin-walled closed beams are deformed, and those cross-sectional deformations produce local deformations around the joint part. To represent joint flexibility correctly, therefore, a beam theory taking account of the cross-sectional deformation is required. Based on the thin-walled beams theory initially developed by Vlasov (1961), Kim et al. (2000) have built up higher-order beam theory where kinematic variables associated with warping and distortional deformations are used in addition to the standard Timoshenko kinematic variables.

The difficulty of implementing the higher-order theory is that unlike the Timoshenko beam theory, the joint matching conditions cannot be derived directly from resultant forces equilibrium because forces associated with warping and distortion are self-equilibrated meaning that they do not produce any resultant forces. Consequently, a difficult task understanding how the complex local deformations around joint are developed in conjunction with the kinematic variables of the higher-order beam theory should be performed.

In this work, we report some recent progress toward matching of the field variables of the higher-order beam theory for thin-walled box-beam structures. Two box beams are assumed to meet at an arbitrary angle. For this study, two loading cases are treated separately as they produce decoupled deformations: out-of-plane loading and in-plane loading. For each loading case, the exact joint matching conditions are theoretically derived without assumptions, and they are explicitly written in a matrix form with the joint angle and material/geometry of two joining box beams. The validity of the derived joint matching conditions is demonstrated by showing good agreement between shell FE results and the results obtained by higher-order beam FE model incorporating the newly-derived joint matching conditions for various numerical examples.

Authors

Jieun Yang, Yoon Jae Kim and Yoon Young Kim

Title

Topology Optimization of an Acoustic Diffuser Considering Reflected Sound Field

Conference

CODE(Computational Design in Engineering) 2012

Vol/No

PP

Year/Month

2012-11-01 제주, 휘닉스 아일랜드

Link

Abstract

Authors

Young Eui Kwon, Hyun Joong Jeon, Hoe Woong Kim, and Yoon Young Kim

Title

Beam width control of ultrasonic shear waves using linearly tapered waveguide transducers

Conference

2012 IEEE IUS

Vol/No

PP

Year/Month

2012-10-01 Dresden, Germany

Link

Abstract

Authors

Joo Kyung Lee, Hoe Woong Kim, and Yoon Young Kim

Title

Omni-directional Lamb wave by Magnetostrictive Patch Transducer

Conference

2012 IEEE IUS

Vol/No

PP

Year/Month

2012-10-01 Dresden, Germany

Link

Abstract