• Journal of the Korean Society for information Management
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• v.5 no.2
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• pp.3-22
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• 1988

The purpose of this paper is to help understand of the, definitio~~ of, componativelibraianship and the methodology of comparative study in librariansliip. Comparative librarial~sl~ip may be defined as the systematic anallsis of library derelopmetit, practices, or problems as they occur under different circumstances (most usually in different count r ~ e s ) , considered in the c o ~ t t x t of tlle relevant historical, geographic, political, economic, social, cultural, and other determinant backgrourd factors found in the situations under study. Essentially it co~~stitutes an important approach to the search for cause and effect in library development, and tu tl~e understandillg of library problems. The mctl~odology of comparatiw study i n libranianship includes four steps; i)description, iilinterpret at ion, iii\ulcorner juxtaposition, iv! comparison.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.343-346
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• 2005

Three dimensional structures of detonation wave propagating through a square-shaped duct were investigated using computational method and parallel processing. Inviscid fluid dynamics equations coupled with $variable-{\gamma}$ formulation and simplified one-step Arrhenius chemical reaction model were analysed by MUSCL-type TVD scheme and four stage Runge-Kutta time integration. The unsteady computational results in three dimension show the detailed mechanism of transverse mode and diagonal mode of detonation wave instabilities resulting same cell length but different cell width in smoked-foil record.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.53-55
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• 2013

In general, various numerical techniques such as MoM, TLM, FEM, and BEM can be introduced to analyze some microwave device and electromagnetic propagation problems. Numerical simulator based on Java thread-level parallelism for improving computation performance is implemented and estimated.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.34-36
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• 2017

축류 팬(axial fan)은 팬이 회전하면서 다량의 공기를 불어주는 유체 기계로써 최근 저소음에 대해 중요하게 인식되고 있다. 본 연구는 팬 주위의 소음을 해석하는 MPI 병렬프로그램에 대한 최적화 기법에 대해 다룬다. 이때 수억 개 이상의 격자에서 수만 포인트의 소음을 해석하기 위해서 MPI 프로세스 간 통신이 많이 발생하여 성능이 심각하게 느려지는 현상이 발생한다. 이를 극복하기 위해 MPI 일방향통신을 적용하였다. 뿐만 아니라 통신 및 메모리 최적화 방법을 통해 최대 2.97배 향상시켰다.

• Journal of the Korea Society for Simulation
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• v.26 no.3
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• pp.13-22
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• 2017

This research proposes and applies a pipelining parallel processing technique to enhance the speed of visualizing the results of real-time simulations. Generally, a simulation with real-time visualization consists of three processes: executing a simulation model, transmitting simulation result, and visualizing simulation result. If we have these processes in serial, the latency from simulation to visualization will be very long, which degrades the speed of visualization of data from real-time simulation. Thus, the main purpose of this research is maximizing performance by adapting pipelining parallel processing technique to the real-time simulation visualization. Also we show that performance is improved by adding multi-threading technique to each process. This paper proposes a theoretical performance model and simulation results of the techniques and then we applied this to an air combat simulation model as a case study. As the result, it shows that the performance is greatly enhanced than the original model's execution time.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.8
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• pp.46-55
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• 2002

A nonlinear aeroelastic analysis system in transonic and supersonic flows has been developed using high speed parallel processing technique on the network based PC-clustered machines. This paper includes the coupling of advanced numerical techniques such as computational structural dynamics (CSD), finite element method (FEM) and computational fluid dynamics (CFD). The unsteady Euler solver on dynamic unstructured meshes is employed and coupled with computational aeroelastic solvers. Thus it can give very accurate engineering data in the structural and aeroelastic design of flight vehicles. To show the great potential of useful application, transonic and supersonic flutter analyses have been conducted for a complete aircraft model under developing in Korea.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.942-945
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• 2009

유한차분시간영역 방법은 전자기파 관련 분야의 전산모사에 많이 사용되는 수치해석기법이다. 이 방법을 이용하여 구현한 전산모사 프로그램은 많은 계산 자원 필요로 하기 때문에 병렬 계산 환경을 이용하게 되는 경우가 많다. 병렬 계산 환경에서 전산모사를 수행할 경우, 병렬로 수행되는 각 프로세스 간의 통신 속도와 네트워크의 지연 시간은 계산의 병목 현상을 초래하여 전체적인 성능을 저하시키는 원인이 된다. 따라서, 본 논문에서는 MPI의 지속 통신 메커니즘을 이용하여 병렬 프로세스 간 동기화 속도를 증가시킴으로써 유한차분시간영역 전산모사 프로그램에서의 MPI 통신 성능의 향상을 꾀하고, 그 결과를 그래프로 도시하였다. 또한 기존의 양방향 통신과 단방향 통신 메커니즘을 사용했을 때의 성능과 비교/분석하여, 병렬 유한차분시간영역 전산모사 프로그램에 있어서 지속 통신 메커니즘의 장/단점을 제시하고, 그 효용성에 관해 논의한다.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3175-3177
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• 2000

전압원과 전류원 및 RLC 수동소자들로 구성된 대형회로망에서 망(網)과 마디를 복합시킨 새로운 회로망 해석법을 제시하였다. 종래의 수식적 유도 과정이 불필요하며 도식적 추출에 의해 대형회로망을 간단히 해석한다 각 전원은 직렬 또는 병렬 임피던스를 반드시 수반하고 있지 않아도 무방하다. 망 설정과 마디 선정 과정에서의 전원 처리에 의해 회로망의 도형화 시켰고, 그로부터 행렬 형태의 부분 식을 도출하였다. 망해석법에 의한 방식과 마디해석법에 의한 기법이 가지전류방향 행렬에 의해 합성된다. 합성된 최종 식은 컴퓨터 몫이다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.11 s.254
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• pp.1447-1454
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• 2006

The evaluation of parallel performance of a high speed impact simulation is not an easy task because not only the development of parallel explicit code is difficult but also a large number of processors is not easily accessible. In this paper, the parallel performance of a new Lagrangian FEM impact code carried out on cluster supercomputer has been described in high speed range. In the case of metal sphere impacting to oblique plate, the overall speed-up continuously increases even up to 128 CPUs. Investigation of elapsed time of each part reveals that most of the inefficiency comes from the load imbalance of contact.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.8
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• pp.1043-1050
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• 2013

Parallel robots used in industry require high stiffness or high speed because of their structural characteristics. Nowadays, the importance of rapid transportation has increased in the distribution industry. In this light, an industrial parallel robot has been developed for high-speed transfer. The developed parallel robot can handle a maximum payload of 3 kg. For a payload of 0.1 kg, the trajectory cycle time is 0.3 s (come and go), and the maximum velocity is 4.5 m/s (pick amp, place work, adept cycle). In this motion, its maximum acceleration is very high and reaches approximately 13g. In this paper, the design, analysis, and performance test results of the developed parallel robot system are introduced.