• 한국자동차공학회논문집
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• 제6권3호
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• pp.143-153
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• 1998

In this reaserch, a program for real time simulation of a vehicle is developed. This program uses relative coordinates to save the computation time and BDF(Backward Difference Formula) to integrate system variables. Numerical tests were performed for J-turn and Lane change steering, respectively. The validity of the program is proved by the ADAMS package. Numerical results showed that the proposed implicit method is more stable in carrying out the numerical integration for vehicle dynamics than the explicit method. Hardware requirements for real time simulation are suggested.

• 대한기계학회논문집B
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• 제22권1호
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• pp.104-112
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• 1998

The mold filling process has been a central issue in the development of numerical methods to solve the casting processes. A mold filling which is inherently transient free surface fluid flow, is important because the quality of casting highly depends on such phenomenon, Most of the existing numerical schemes to solve mold filling process have severe limitations in time step restrictions or Courant criteria since explicit time integration is used. Therefore, a large computation time is required to analyze casting processes. In this study, the well known SOLA-VOF method has been modified implicitly to simulate the mold filling process. Solutions to example filling problems show that the proposed method is more efficient in computation time than the original SOLA -VOF method.

• 한국컴퓨터그래픽스학회논문지
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• 제5권1호
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• pp.27-33
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• 1999

본 논문은 유연한 비정형 물체의 애니메이션을 위한 효율적인 기법을 제안한다. 비정형 물체를 표현하기 위해 질량-스프링 모텔이 사용되었다. 지금까지 많은 기법들이 부드러운 객체의 사실적인 애니메이션을 생성하기 위해 질량-스프링 모델을 사용하였다. 질량-스프링 모텔의 애니메이션을 수행하기 위한 가장 손쉬운 접근법은 명시적 오일러 방법 (explicit Euler method)인데, 이 방법은 '불안정성 문제'라는 잘 알려진 문제가 발생한다는 단점을 가지고 있다. 이 불안정성 문제를 해결하기 위한 해법으로 암시적 적분법이 사용될 수 있다. 그러나, 이 암시적 방법의 가장 결정적인 약점은 대규모의 선행 시스템을 풀어야 한다는 것이다. 본 논문은 암시적 방법의 근사(approximation)를 이용하여 질량-스프링 모델을 빠른 시간에 애니메이션 할 수 있는 기법을 제시한다. 제안된 기법은 n 개의 질점이 O(n) 개의 스프링으로 연결되어 있을 때, 각 질점의 상태를 O(n) 시간에 안정적으로 갱신할 수 있다. 본 논문은 사실적인 결과를 위해 비정형 물체와 공기와의 상호 작용도 고려하였다.

• 지식경영연구
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• 제9권1호
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• pp.97-116
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• 2008

The purpose of this study lies in examining how knowledge management was applied to PMI(Post Merger Integration) in bank merger. Individuals and organizations in Korea have experienced a lot of changes since the 1997 foreign exchange crisis. In such a situation, individuals came to think the only thing to rely on was personal knowledge. Since organizations had to lay off workers in order of their birth year, not based on whether or not individuals had the knowledge necessary for the organizations, they needed to have such a system that could use their explicit knowledge and even outside knowledge or customers' knowledge as IT developed by changing individuals' tacit knowledge into explicit knowledge as needed in order to continue to maintain their competitiveness and for their own development. Thus, each firm started to pitch for the introduction of knowledge management. Individuals started to store their own experience and knowledge in their homepages or blogs. It was Woori Bank, the merged bank of Hanil Bank and Commercial Bank of Korea, that introduced the knowledge management system and Shared Service Center, in which knowledge creation is available, for the first time in the banking business. Its previous name was Hanbit Bank. Hanbit Bank wanted to construct an advanced bank system, bringing in their chief information officer(CIO) from a foreign bank and introducing an IT software used in Spanish banks to adjust all banking processes to it. However, they could not help giving up the plan in the middle of the road since there was a great difference between Spain and Korea in the financial system and more than 30% of software package had to be changed. In this situation, PMI was delayed, and customer inconvenience continued, which made the integration of organizational cultures slow down. As a breakthrough in this situation, knowledge management was introduced. To integrate knowledge of two organizations in the process of PMI is an important job for all merger candidates. This study aims at presenting the successful results from using knowledge management as a means to PMI ahead of other financial institutions so they can apply them to their organizations. PMI was not achieved properly after the two banks had been merged as Hanbit, but entering the era of Woori Bank, workers were integrated under one standard organization following the organizational and knowledge integration, and knowledge management was introduced for an efficient sharing of knowledge among members. A great number of mergers have occurred up to now, but Woori Bank is the first case that used knowledge management as a means to both PMI and competitiveness enhancement. Probably it was an appropriate time when Woori Bank introduced knowledge management as it was organized. Since Hanil Bank and Commercial Bank of Korea had not introduced knowledge management until then, it could use knowledge management as a means to PMI. Using knowledge management, it could create a new organizational culture and increase competitiveness in the banking industry.

• Structural Engineering and Mechanics
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• 제20권2호
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• pp.241-257
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• 2005

A numerical approach combining the finite element method with two different stability criteria namely the Budiansky and the phase-plane buckling criteria is used to study the dynamic buckling phenomena of plate and shell structures subjected to sudden applied loading. In the finite element analysis an explicit time integration scheme is used and the two criteria are implemented in the Finite Element analysis. The dynamic responses of the plate and shell structures have been investigated for different values of the plate and shell imperfection factors. The results indicate that the dynamic buckling time, which is normally considered in predicting elasto-plastic buckling behavior, should be taken into consideration with the buckling criteria for elastic buckling analysis of plate and shell structures. By selecting proper control variables and incorporating them with two dynamic buckling criteria, the unique dynamic buckling load can be obtained and the problems of ambiguity and contradiction of dynamic buckling load of plate and shell structure can be resolved.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.55-60
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• 2004

This study is concerned to the perforation phenomena of the oblique dual-plate by projectile. Experiment and simulation related to that was carried out. the variables considered in this phenomena include the electrolytic zinc coated steel sheet and carbon steel rod. In the former, the confirmation and projectile velocity possible phenomena of real phenomena is done, the latter, the effect of parameter such as time-step and grid space length is analized by using the three-dimensional Lagrangian explicit time-integration finite element code, HEMP. this code use the eight node hexahedral elements and in this study, Von-Mises Criteria is used as the strength model, Mie-Gruneisen is as the Equation of State. the simulation was performed by contrast with the experiment. through the calibration of the parameter of lagrangian code, reasonable result was approached.

• 전산구조공학
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• 제8권3호
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• pp.59-66
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• 1995

점소성이론을 이용하여 충격하중을 받는 구조물의 거동을 하중시간에 따라 조사하였다. 점소성이론은 재료의 소성특성과 시간변화특성을 나타내는 Rheology 이론을 동시에 고려한 이론이다. 점소성 구성방정식을 구한 후, 이를 이차원 유한요소해석프로그램에서 심어서 평면응력, 평면 변형률, 축대칭 구조물의 동적 거동을 해석할 수 있도록 기존프로그램을 수정.개발하였다. Perzyna에 의한 점소성 구성방정식은 유한요소해석에서 Explicit 적분법을 사용해야 하는데 반하여, 본 연구에서 구한 구성방정식은 Implicit 적분법을 적용할 수 있도록 Algorithm을 개발하였다. 다양한 하중시간을 갖는 충격하중을 선택한 구조물에 가해 해석한 결과, 하중시간이 길수록 변형이 증가하여 점소성 거동을 하며, 높은 고유진동수 성분이 점소성거동으로 거의 소멸된다는 결론을 얻었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2001년도 춘계 학술대회논문집
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• pp.38-44
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• 2001

An efficient Gauss-Seidel time integration scheme is developed for solving the Euler and Navier-Stokes equations on unstructured meshes. Roe's FDS is used for the explicit residual computations and van Leer's FVS for evaluating implicit flux Jacobian. To reduce the memory requirement to a minimum level, off-diagonal flux Jacobian contributions are repeatedly calculated during the Gauss-Seidel sub-iteration process. Computational results based on the present scheme show that approximately $15\%$ of CPU time reduction is achieved while maintaining the memory requirement level to $50-60\%$ of the original Gauss-Seidel scheme.

• 대한기계학회논문집B
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• 제28권5호
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• pp.553-559
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• 2004

Stratified flow past a three-dimensional obstacle such as a sphere has been a long-lasting subject of geophysical, environmental and engineering fluid dynamics. In order to investigate the effect of the stratification on the near wake, in particular, the unsteady vortex formation behind a sphere, numerical simulations of stratified flows past a sphere are conducted. The time-dependent Navier-Stokes equations are solved using a three-dimensional finite element method and a modified explicit time integration scheme. Laminar flow regime is considered, and linear stratification of density is assumed under Bossiness approximation. The computed results include the characteristics of the near wake and the unsteady vortex shedding. With a strong stratification, the separation on the sphere is suppressed and the wake structure behind the sphere becomes planar, resembling that behind a vertical cylinder.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.715-720
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• 2000

Stratified flow past a three-dimensional obstacle such as a sphere has been a long-lasting subject of geophysical, environmental and engineering fluid dynamics. In order to investigate the effect of the stratification on the near wake, in particular, the unsteady vortex formation behind a sphere, numerical simulations of stratified flows past a sphere are conducted. The time-dependent Navier-Stokes equations are solved using a three-dimensional finite element method and a modified explicit time integration scheme. Laminar flow regime is considered and linear stratification of density is assumed under Boussinesq approximation. The computed results include the characteristics of the near wake and the unsteady vortex shedding. With a strong stratification, the separation on the sphere is suppressed and the wake structure behind the sphere becomes planar, resembling that behind a vertical cylinder.