• 전기학회논문지P
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• 제59권2호
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• pp.185-190
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• 2010

This paper presents the estimation on switching technique via output power source analysis of power conversion unit in electric railway vehicle. The focus of this study suggested an alternative on critical problems by using head electric power(HEP). To achieve this, we have measured output power of HEP, and measurement devices set up at output of transformer connected HEP to analysis quality on output power source of head electric power(HEP) unit in electric railway vehicle. Using results of measurement of it, parameters are assumed for simulation to confirm estimation on switching technique. It is confirmed that switching technique is Selected Harmonic Elimination PWM(SHEPWM) and inverter switching frequency is less than 500[Hz]. Throughout experiment and simulation, it is estimated that switching technique used HEP is advanced SHEPWM and switching frequency is about 300[Hz]. Also leakage inductance in transformer is about $180[{\mu}H]$ less than $365[{\mu}H]$ known.

• Smart Structures and Systems
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• 제20권4호
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• pp.473-481
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• 2017

This study suggests a simple, convenient and non-destructive method for investigation of the Young's modulus detection in stepped shafts which only utilizes the first-order resonant frequency in flexural mode and dimensions of structures. The method is based on the impulse excitation technique (IET) to pick up the fundamental resonant frequencies. The standard Young's modulus detection formulas for rectangular and circular cross-sections are well investigated in literatures. However, the Young's modulus of stepped shafts can not be directly detected using the formula for a beam with rectangular or circular cross-section. A response surface method (RSM) is introduced to design numerical simulation experiments to build up experimental formula to detect Young's modulus of stepped shafts. The numerical simulation performed by finite element method (FEM) to obtain enough simulation data for RSM analysis. After analysis and calculation, the relationship of flexural resonant frequencies, dimensions of stepped shafts and Young's modulus is obtained. Numerical simulations and experimental investigations show that the IET method can be used to investigate Young's modulus in stepped shafts, and the FEM simulation and RSM based IET formula proposed in this paper is applicable to calculate the Young's modulus in stepped shaft. The method can be further developed to detect mechanical parameters of more complicated structures using the combination of FEM simulation and RSM.

• 터널과지하공간
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• 제19권3호
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• pp.190-202
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• 2009

발파해체는 다른 해체방법과는 달리 실패에 따라 발생할 수 있는 인적 물적 자원의 손실이 매우 크기 때문에, 이를 사전에 예측 방지 할 수 있는 수치해석을 이용한 시뮬레이션 개발이 필수적이라 할 수 있다. 본 연구에서는 기둥 보 접합부의 특성구현 및 철근과 콘크리트의 강도 구현 등에 관하여 유한 요소법에 바탕을 둔 상용코드인 LS-DYNA를 이용하여, 실제 발파대상 구조물이 가지고 있는 복잡한 철근 배근을 단순화하여 고려하는 기법을 제안 하였으며, 또한 본 연구에서 제안한 기법을 이용하여 축소모형 실험 및 실제 구조물의 발파해체의 모사를 통해 검증하였다.

• Journal of Power Electronics
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• 제11권2호
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• pp.173-178
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• 2011

In order to verify the performance of brushless DC (BLDC) motors, the simulation method has been widely used. The current of a BLDC motors flows on two phase windings to obtain a constant torque. However, the freewheeling current caused by the inductance component of a BLDC motor exists at the commutation point so that the current can flow on three phase windings at the same time. Due to the changes of the excited phases, the model equations are frequently changed during BLDC motor drive operation. The model equations can be also changed by the applied switching pattern since the current path in the inverter circuit changes according to switching pattern. A BLDC motor system can utilize various switching patterns for many different purposes. However, such changes of the model equations complicate the simulation procedure. In this paper, the technique to set up model equations is proposed to ease the simulation of a BLDC motor system through an inverter circuit analysis. The proposed technique will be verified using the C language. Although this method does not provide the level of detail obtainable from commercial simulation tools like PSIM or SIMULINK, it can provide an efficient way to quickly compare various conditions.

• 한국CDE학회논문집
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• 제5권4호
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• pp.347-358
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• 2000

The view dependency of typical spatial-partitioning based NC simulation methods is overcome by polygon rendering technique that generates polygons to represent the workpiece, thus enabling dynamic viewing transformations without reconstruction of the entire data structure. However, the polygon rendering technique still has difficulty in realizing real-time simulation due to unsatisfactory performance of current graphics devices. Therefore, it is necessary to develop a mesh decimation method that enables rapid rendering without loss of display quality. In this paper. we proposed a new mesh decimation algorithm thor a workpiece whose shape varies dynamically. In this algorithm, the 2-map data thor a given workpiece is divided into several regions, and a triangular mesh is constructed for each region first. Then, if any region it cut by the tool, its mesh is regenerated and decimated again. Since the range of mesh decimation is confined to a few regions, the reduced polygons for rendering can be obtained rapidly. Our method enables the polygon-rendering based NC simulation to be applied to the computers equipped with a wider range of graphics cards.

• 한국차세대컴퓨팅학회논문지
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• 제15권4호
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• pp.51-61
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• 2019

이 논문에서는 유체 시뮬레이션 기술을 사용해서 비유체인 토사를 시뮬레이션하는 방법을 구현했다. 굴착 작업 등에 의해 생성되는 토사를 표현하기 위해 널리 사용되는 NVIDIA 사의 FleX를 사용하였다. FleX는 SPH(Smoothed-particle hydrodynamics) 기법과 위치 기반 동역학 (Position Based Dynamics) 기법을 결합한 입자 기반 물리 시뮬레이션 라이브러리로서 이를 이용하면 유체를 실감 있게 표현할 수 있다. 그러나 토사는 유체의 성질뿐만 아니라 비유체의 성질도 가지고 있기 때문에 기존의 FleX가 제공하는 기능만으로 시뮬레이션하기 어렵다. 본 연구에서는 기존 Flex를 이용하여 비유체의 행태를 시뮬레이션하기 위한 기법을 추가하였다. 이를 통해 적은 비용으로 효과적인 결과 개선이 이루어질 수 있다.

• 한국정밀공학회지
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• 제13권11호
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• pp.114-123
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• 1996

The major objective of the present paper is to estabilish analytical technique in order to closely understand and analyze the actual shearing process. First of all, isothermal and non-isothermal FE-simulation of the shearing process are carried out using finite element software DEFORM. Based on preliminary simulation using DEFORM, the finite element program to analyze two dimensional shearing process is developed. The ductile fracture criterion and the element kill method are also used to estimate if and where a fracture will occur and to investigate the features of the sheared surface in shearing process. It can be seen that the developed program combined with the ductile fracture criterion and element kill method has enabled the achievement of FE-simulation from initial stage to final stage of shearing process. The effects of punch-die clearance on shearing process are also investigated. In order to verify the effectiveness of the proposed technique the simulation results are compared with the known expermental data. It is found that the results of the present work are in close agreement with the published experimental results.

• 전자공학회논문지D
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• 제36D권3호
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• pp.48-58
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• 1999

본 연구에서는 3차원 반도체 공정 시뮬레이션의 효율성과 성능을 향상시키기 위하여, 병렬 유한요소법 수치해석에 사용이 적합한 디라우니 병렬 메쉬 생성기 및 표면 전진 메쉬 생성기를 개발하였고, 이를 위하여 개선된 성능을 보이는 수정된 하부구조법 병렬 유한요소법 수치해석기를 개발하였다. 또한, 행렬 계산 알고리즘의 병렬화를 확산 및 산화 시뮬레이터에 적용하여, 직렬 계산 시 3시간이 소요되는 확산 시뮬레이션과 비평탄 구조를 지니는 R-LOCOS 등의 연산을 8개의 프로세서를 병렬로 사용하여 15분만에 계산하였다. 과다한 계산 시간을 요하는 몬테카를로 수치해석 방법의 효율성을 높이고자, 병렬 연산 알고리즘을 몬테카를로 연산에 적용하였다. 또한, 스퍼터링 증착장치 시스템의 타켓 입자 분포 특성을 병렬 연산 몬테카를로 방식으로 계산하였다. 3000개의 이온을 주입하였을 겨우 단일 프로세서에서 13,000초의 계산시간이 소요되었으나, 30개의 프로세서를 병렬로 사용하였을 때 520초의 시간을 소비하여,25 이상의 스피드업 특성을 얻었다. 또한, 몬테카를로 계산의 최적화 연구를 통해서 3차원 스퍼터링 증착장치에서 연쇄 충돌 계산 수행시의 최적이온의 개수는 30,000임을 확인하였다.

• 산업공학
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• 제1권1호
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• pp.27-37
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• 1988

In the multi-stage and multi-process plant, it is not an easy task to describe the interrelationships among each process and facility. The purpose of this simulation study is to analyze the effect of additional facilities on productivity in a steel mill. The simulation was performed using SLAM Simulation Language for Alternative Modeling. The results of this study was used by the plant engineers in making decisions on the expansion of the plate mill. The prediction of which process would cause bottle-necks enabled the plant engineers to invest most effectively.

• 산업경영시스템학회지
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• 제18권34호
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• pp.115-121
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• 1995

The objective of this study is to develope an effectiveness measurement technique for U-shaped JIT production line by computer simulation. A small and medium sized automobile brake master cylinder manufacturing plant is studied for productivity improvement The production line is analysed and improved by applying Low Cost Automation, special jigs and fixtures, and facilities layout changes. An experimental simulation model is built using SIMAN(SIMulation ANalysis) simulation software for the production system analysis.