• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.12-14
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• 2002

In this paper, magnetic force on acting arc was analyzed by 3-D FEM for three DC arc-quenching rooms having different magnetic flux paths. We measured arc breaking time in prototypes by experiment so that we compared the relation of magnetic force and arc breaking time. Finally, we present the techniques for magnetically-driven arc and for the prediction of arc breaking time.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.80-87
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• 1996

The present paper will give some results of the fatigue behavior of typical axi-symmetric forward extrusion die. The extrusion process is analyzed by rigid-plastic FEM and the deformation analysis of extrusion die is conducted by elasto-plastic FEM. To approach the crack problem LEFM (Linear Elastic Fracture Mechanics) is introduced. Using special element in order to conside the sigularity of stress/ strain in the vicinity of the crack tip, stress intensity factor and the effective stress intensity factor is calculated. Applying proper fatigue crack propagation criterion such as Paris/Erdogan fatigue law and maximum principal criterion to these data, then, the angle and the direction of fatigue crack propagation is simulated. In result, it is proved that the simulated fatigue crack propagates in the zigzag path along the radial direction and fatigue life of the extrusion die is evaluated by using the computed crack growth rate.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.2
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• pp.173-178
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• 2015

Laser-assisted machining (LAM) is an effective machining method for processing difficult-to-cut materials. Prediction and estimation of preheating effect of the LAM is difficult because of moving heat source. So it is necessary to study the preheating effect of the laser heat source irradiated on the curved surfaces of workpieces of various shape. In this paper, thermal analysis of the LAM for 3-dimentional workpiece with cylindrical shape was performed. The results of this analysis can be applied to obtain the optimal preheating method and path for LAM of 3-dimensional workpiece.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.256-258
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• 2005

분자모델링 시뮬레이션 도구는 신 물질과 신약개발을 위한 가상 실험을 하는데 사용되는 중요한 도구이다. 이 도구는 분자 물질간의 결합을 통하여 에너지 계산을 하여 가장 낮은 에너지 준위를 보여주는 위치를 탐색한다. 에너지 결과를 빠르게 제공하면 사용자가 분자 물질을 결합하여 안정된 위치를 찾는데 많은 도움을 줄 수 있다. 본 연구에서는 에너지 계산을 고성능으로 처리 할 수 있는 분산처리시스템과 실시간 응답성 보장 스케줄링 알고리즘을 적용한 환경에 사용자 입력 예측 시스템을 추가하여 에너지 계산을 기존 시스템 보다. 빠르게 요청하였으며, 에너지 계산 결과의 응답성을 향상 시켰다. 또한 사용자 입력 예측시스템에서 발생하는 오차의 문제를 예측 시스템의 운영 방식을 통해 해결 방법을 제시하고 있다. 본 연구는 에너지 결과의 응답성 보장을 통하여 사용자가 좀 더 빠르게 안정된 결합 위치를 찾도록 도와준다.

• Korean Journal of Construction Engineering and Management
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• v.6 no.1 s.23
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• pp.73-79
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• 2005

This paper, introduces a Stochastic Project Scheduling Simulation system (SPSS III) developed by the author to predict a project completion probability in a certain time. The system integrates deterministic CPM, probabilistic PERT, and stochastic Discrete Event Simulation (DES) scheduling methods into one system. It implements automated statistical analysis methods for computing the minimum number of simulation runs, the significance of the difference between independent simulations, and the confidence interval for the mean project duration as well as sensitivity analysis method in What-if analyzer component. The SPSS 111 gives the several benefits to researchers in that it (1) complements PERT and Monte Carlo simulation by using stochastic activity durations via a web based JAVA simulation over the Internet, (2) provides a way to model a project network having different probability distribution functions, (3) implements statistical analyses method which enable to produce a reliable prediction of the probability of completing a project in a specified time, and (4) allows researchers to compare the outcome of CPM, PERT and DES under different variability or skewness in the activity duration data.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.473-478
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• 2004

This work presents the Thermal Hydraulic analysis has been performed for a 19-pin wire-spacer fuel assembly using three-dimensional Reynolds-averaged Navier-Stokes equations. SST model is used as a turbulence closure. The whole fuel assembly has been analyzed for one period of the wire-spacer using periodic boundary condition at inlet and outlet of the calculation domain. The overall results far a preliminary calculation show a good agreement with the experimental observations. It has been found that the major unidirectional flows are the axial velocity in sub-channels and the peripheral sweeping flows and the velocities are found to be following a cyclic path of period equal to the wire-wrap pitch. The temperature is found to be maximum in the central region and also, there exist a radial temperature gradient between the fuel rods. The major advantage of performing this kind of analysis is the prediction of thermal-hydraulic behavior of a fuel assembly with much ease.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.81-86
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• 2007

Spectral features of the seismic wave propagation from Odaesan Earthquake were evaluated based on the commonly treated random error between the observed data and the prediction values by the stochastic point-source ground-motion spectral model regarding the source, path and site effects. Radiation pattern of the error according to azimuth angle was found to be similar to the theoretical estimate. It was also observed that the spatial distribution of the errors was correlated with the geological map and the Q0 map which are indicatives of seismic boundaries.

• Journal of Welding and Joining
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• v.25 no.5
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• pp.72-77
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• 2007

Prediction and control of the thermal distortion is particularly important for the design and manufacture of welded thin metal structure. In this study, numerical computations are performed to analyze effect of structure section shape and weld line location on distortion. In addition, this study aims to develop a thermal elasto-plastic simulation using finite element method to predict distortion, with particular emphasis on bending deformation generated in outline welding of a thin box structure. From the numerical analysis, it was revealed that the section shape and weld line location play an important role on the welding distortion. Among 3 types of section shape design proposed in this study, the least deformation remained in the two path welded structure.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.723-724
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• 2006

Exploiting the instruction level parallelism encountered with the limit. Single chip multiprocessor was introduced to overcome the limit of traditional processor using the instruction level parallelism. Also, a branch miss prediction is one of the causes that reduce the processor performance. In order to overcome the problems, in this paper, we make single chip multiprocessor having the idle core execute the two control flow of conditional branch. This scheme is a kind of multi-path execution technique based on single chip multiprocessor architecture.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.586-593
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• 2001

본 논문에서는 Cost231-Hata 모델과 Cost231-Walfisch-Ikegami 모델을 비교 분석하고, 두 모델의 전파환경이 서로 근접하게 되는 송신안테나의 높이, 건물군의 높이, 그리고 도로폭의 상관관계를 나타내는 전송손실 곡선들을 제시한다. 이러한 곡선들은 Okumura-Hata 모델의 정성적인 전파환경(도심지, 교외지역, 개활지)을 정량적인 요소(건물군의 높이, 도로폭) 로서 설명하여, Okumura-Hata(Cost231-Hata) 모델을 다른 도시, 나라에 적용시킬 때 하나의 기준으로 활용 될 수 있을 것이다. 또한 최근에 제안된 ITU-R 모델과 Okumura-Hata(Cost231-Hata)모델을 비교 분석한 결과, ITU-R 곡선들은 Okumura-Hata의 교외지역 전파환경에 대한 사용식을 확장한 것으로 사료된다.