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THE EFFECTS OF MESH STYLE ON THE FINITE ELEMENT ANALYSIS FOR ARTIFICIAL HIP JOINTS
JAEMIN SHIN,DONGSUN LEE,SUNGKI KIM,DARAE JEONG,HYUN GEUN LEE,JUNSEOK KIM 한국산업응용수학회 2011 Journal of the Korean Society for Industrial and A Vol.15 No.1
In this paper, a good quality mesh generation for the finite element method is investigated for artificial hip joint simulations. In general, bad meshes with a large aspect ratio or mixed elements can give rise to excessively long computational running times and extremely high errors. Typically, hexahedral elements outperform tetrahedral elements during three-dimensional contact analysis using the finite element method. Therefore, it is essential to mesh biologic structures with hexahedral elements. Four meshing schemes for the finite element analysis of an artificial hip joint are presented and compared: (1) tetrahedral elements, (2) wedge and hexahedral elements, (3) open cubic box hexahedral elements, and (4) proposed hexahedral elements. The proposed meshing scheme is to partition a part before seeding so that we have a high quality three-dimensional mesh which consists of only hexahedral elements. The von Mises stress distributions were obtained and analyzed. We also performed mesh refinement convergence tests for all four cases.
HIGHER ORDER OPERATOR SPLITTING FOURIER SPECTRAL METHODS FOR THE ALLEN–CAHN EQUATION
JAEMIN SHIN,HYUN GEUN LEE,JUNE-YUB LEE 한국산업응용수학회 2017 Journal of the Korean Society for Industrial and A Vol.21 No.1
The Allen–Cahn equation is solved numerically by operator splitting Fourier spectral methods. The basic idea of the operator splitting method is to decompose the original problem into sub-equations and compose the approximate solution of the original equation using the solutions of the subproblems. The purpose of this paper is to characterize higher order operator splitting schemes and propose several higher order methods. Unlike the first and the second order methods, each of the heat and the free-energy evolution operators has at least one backward evaluation in higher order methods. We investigate the effect of negative time steps on a general form of third order schemes and suggest three third order methods for better stability and accuracy. Two fourth order methods are also presented. The traveling wave solution and a spinodal decomposition problem are used to demonstrate numerical properties and the order of convergence of the proposed methods.
A CONSERVATIVE NUMERICAL METHOD FOR THE CAHN-HILLIARD EQUATION IN COMPLEX DOMAINS
Jaemin Shin,Darae Jeong,Junseok Kim 한국산업응용수학회 2011 한국산업응용수학회 학술대회 논문집 Vol.6 No.1
We propose an efficient finite difference scheme for solving the Cahn-Hilliard equation with a variable mobility in complex domains. Our method employs a type of unconditionally gradient stable splitting discretization. We also extend the scheme to compute the Cahn-Hilliard equation in arbitrarily shaped domains. We prove the mass conservation property of the proposed discrete scheme for complex domains. The resulting discretized equations are solved using a multi grid method. Numerical simulations are presented to demonstrate that the proposed scheme can deal with complex geometries robustly. Furthermore, the multigrid efficiency is retained even if the embedded domain is present.
Image-Recognition-Based Embedded System for Excavator Bucket Tracking in Construction Sites
Jaemin Shin,Hyunbin Park,Hyeonjae Jeong,Hyeongyeong Jeong,Beaksuk Chu 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.25 No.8
Construction sites involving excavators often generate substantial amounts of fine dust at the operating position of the excavator bucket. To address the problem, this research proposes a system that tracks the excavator’s bucket using only a single camera and an artificial intelligence-based image recognition algorithm, aiming to improve accuracy and efficiency compared to conventional methods that utilize multiple sensors. To enhance the accuracy of image recognition, a bucket dataset containing background images was utilized. Real-time object tracking performance exceeding 30 FPS was achieved by applying a graphics processing unit optimizer. Moreover, a function was implemented to track a specific object when multiple objects with similar characteristics are detected. The system also features a control system that utilizes these functions to apply a pan-tilt motion mechanism to the camera, enabling the tracking of the identified bucket position. Extensive experiments, including image recognition for tracking objects exhibiting various motion trajectories and estimating the position of invisible objects, have been conducted to validate the performance of the system.
Jaemin Shin,Dong Wook Kim 한국전자파학회 2013 전자파기술 Vol.24 No.2
The current expanding mobile markets incessantly demands small form factor, low power consumption and high aggregate throughput for silicon-level integration such as memory to logic system. One of emerging solution for meeting this high market demand is 3D through silicon stacking (TSS) technology. Main challenges to bring 3D TSS technology to the volume production level are establishing a cost effective supply chain and building a reliable manufacturing processes. In addition, this technology inherently help increase number of IOs and shorten interconnect length. With those benefits, however, potential signal and power integrity risks are also elevated; increase in PDN inductance, channel loss on substrate, crosstalk and parasitic capacitance. This paper will report recent progress of wide IO memory to high count TSV logic device assembly development work. 28 nm node TSV test vehicles were fabricated by the foundry and assembled. Successful integration of memory wide IO chip with less than a millimeter package thickness form factor was achieved. For this successful integration, we discussed potential signal and power integrity challenges. This report demonstrated functional wide IO memory to 28 ㎚ logic device assembly using 3D package architecture with such a thin form factor.
Shin, Jaemin,Kim, Dong Wook The Korean Institute of Electromagnetic Engineerin 2013 전자파기술 Vol.24 No.2
The current expanding mobile markets incessantly demands small form factor, low power consumption and high aggregate throughput for silicon-level integration such as memory to logic system. One of emerging solution for meeting this high market demand is 3D through silicon stacking (TSS) technology. Main challenges to bring 3D TSS technology to the volume production level are establishing a cost effective supply chain and building a reliable manufacturing processes. In addition, this technology inherently help increase number of IOs and shorten interconnect length. With those benefits, however, potential signal and power integrity risks are also elevated; increase in PDN inductance, channel loss on substrate, crosstalk and parasitic capacitance. This paper will report recent progress of wide IO memory to high count TSV logic device assembly development work. 28 nm node TSV test vehicles were fabricated by the foundry and assembled. Successful integration of memory wide IO chip with less than a millimeter package thickness form factor was achieved. For this successful integration, we discussed potential signal and power integrity challenges. This report demonstrated functional wide IO memory to 28 nm logic device assembly using 3D package architecture with such a thin form factor.
Unconditionally stable methods for gradient flow using Convex Splitting Runge–Kutta scheme
Shin, Jaemin,Lee, Hyun Geun,Lee, June-Yub Elsevier 2017 Journal of computational physics Vol.347 No.-
<P><B>Abstract</B></P> <P>We propose a Convex Splitting Runge–Kutta (CSRK) scheme which provides a simple unified framework to solve a gradient flow in an unconditionally gradient stable manner. The key feature of the scheme is a combination of a convex splitting method and a specially designed multi-stage two-additive Runge–Kutta method. Our methods are high order accurate in time and assure the gradient (energy) stability for any time step size. We provide detailed proof of the unconditional energy stability and present issues on the practical implementations. We demonstrate the accuracy and stability of the proposed methods using numerical experiments of the Cahn–Hilliard equation.</P>
Shin, Jaemin,Ko, Eunah,Shin, Changhwan Institute of Electrical and Electronics Engineers 2018 IEEE transactions on electron devices Vol.65 No.1
<P>A negative differential resistance fin-shaped field-effect transistor (NDR-FinFET) using a Pb(Zr<SUB>0.52</SUB>Ti<SUB>0.48</SUB>)O<SUB>3</SUB> threshold selector (TS) is investigated. From the measured input transfer characteristic of NDR-FinFET, the following results are demonstrated: 1) superior reduction of off current by a factor of 350 (as compared to a baseline FinFET); 2) on current of NDR-FinFET comparable to that of the baseline FinFET; and 3) subthreshold slope of 3 mV/decade at 300 K. The operating principle of NDR-FinFET is demonstrated using MATLAB simulation. In the on-to-off and off-to-on switching processes, the existence of an unstable resistive switching region is verified through the comparison between simulation data and experimental results. The major device parameters that affect the formation of the unstable resistive switching region are revealed. Finally, it is proposed that: 1) lowering the hold voltage of the TS and 2) applying the drain voltage comparable to the threshold voltage can have the NDR-FinFET to work appropriately (i.e., not in unstable region).</P>