• 한국산업정보학회논문지
• /
• 제11권5호
• /
• pp.163-169
• /
• 2006

In order to use parallel computers in specific applications, algorithms need to be developed and mapped onto parallel computer architectures. Main memory access for shared memory system or global communication in message passing system deteriorate the computation speed. In this paper, it is found that the m-step generalization of the block Lanczos method enhances parallel properties by forming in simultaneous search direction vector blocks. QR factorization, which lowers the speed on parallel computers, is not necessary in the m-step block Lanczos method. The m-step method has the minimized synchronization points, which resulted in the minimized global communications and main memory access compared to the standard methods.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제49권8호
• /
• pp.509-513
• /
• 2000

This paper deals with the parallel operation of space vector PWM for large capacity inverter system. To enlarge the capacity of inverter system and to reduce the current ripples on inverter output side, two or more inverters are operated in parallel. In this paper, a new parallel operation strategy which minimizes the harmonic distortion of the output stage is described. The proposed method is developed on the basis of the space-vector PWM in order to increase the linearly controllable voltage range. With the help of the proposed voltage synthesis method, the total harmonic distortion of the output stage can be greatly reduced in compared with that of conventional method with sinusoidal PWM or that of the single inverter operation case. The experimental results with reduced scale test show the feasibility of the proposed voltage synthesis method.

• 전력전자학회논문지
• /
• 제25권3호
• /
• pp.235-241
• /
• 2020

In this paper, we propose the bus/bypass synchronization phase lock loop (B-Sync PLL) method using each phase voltage controller of a parallel UPS inverter. The B-Sync PLL included in each phase voltage control system of parallel UPS inverters has the transient response and the phase synchronization error at grid normal or blackout. The validity of this method is verified by simulation and experiment. As a result, the parallel UPS inverters using the proposed method confirmed that the output phase was continuously synchronized when a grid blackout, improving the transient response characteristics for stable load power supply and equal load sharing.

• Structural Engineering and Mechanics
• /
• 제32권1호
• /
• pp.95-126
• /
• 2009

The present contribution addresses the parallelization of advanced simulation methods for structural reliability analysis, which have recently been developed for large-scale structures with a high number of uncertain parameters. In particular, the Line Sampling method and the Subset Simulation method are considered. The proposed parallel algorithms exploit the parallelism associated with the possibility to simultaneously perform independent FE analyses. For the Line Sampling method a parallelization scheme is proposed both for the actual sampling process, and for the statistical gradient estimation method used to identify the so-called important direction of the Line Sampling scheme. Two parallelization strategies are investigated for the Subset Simulation method: the first one consists in the embarrassingly parallel advancement of distinct Markov chains; in this case the speedup is bounded by the number of chains advanced simultaneously. The second parallel Subset Simulation algorithm utilizes the concept of speculative computing. Speedup measurements in context with the FE model of a multistory building (24,000 DOFs) show the reduction of the wall-clock time to a very viable amount (<10 minutes for Line Sampling and ${\approx}$ 1 hour for Subset Simulation). The measurements, conducted on clusters of multi-core nodes, also indicate a strong sensitivity of the parallel performance to the load level of the nodes, in terms of the number of simultaneously used cores. This performance degradation is related to memory bottlenecks during the modal analysis required during each FE analysis.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 D
• /
• pp.2358-2361
• /
• 2003

In this paper, parallel control method that enables coordinating operations of multiple mini ice storage air conditioner is proposed based on LonWorks system. The proposed parallel control method is a kind of master/slave control method based on LonTalk network communication. In the control method, master controller leading whole system operations is determined by date to avoid the disproportion of outdoor unit operations. In addition to the above, duty shift control method is proposed to avoid redundant operations of outdoor units and to equalize the operation frequencies of them. Through some simulation tests, the proposed parallel control method and the duty shift control method are evaluated and the efficiencies of them are validated by comparing with existing methods.

• 한국멀티미디어학회논문지
• /
• 제6권2호
• /
• pp.224-229
• /
• 2003

골격선 추출에 대한 효율적인 방법을 이용해서 골격화방법을 제안한다 제안한 방법은 윤곽선 검출과정을 거친 후 본 방법을 적용함으로써 영상 골격화 효율을 높이고자한다 기존의 골격화 방법은 Zhang, Lu/Wang, 그리고 Paul방법을 사용하였다. 제안된 방법은 병렬적인 처리 방법과 더 해서 반복과정 에서 마스크의 네(화소) 이웃의 값과 네(화소) 이웃외의 주변 화소값을 비교하여 원본이미지와 일치시켜 처리하는 방식이 다. 결론적으로, 제안된 방법은 향상된 골격선의 연결과 품질 등을 보였다.

• Journal of Communications and Networks
• /
• 제16권4호
• /
• pp.436-446
• /
• 2014

The high intensity of research and modeling in fields of mathematics, physics, biology and chemistry requires new computing resources. For the big computational complexity of such tasks computing time is large and costly. The most efficient way to increase efficiency is to adopt parallel principles. Purpose of this paper is to present the issue of parallel computing with emphasis on the analysis of parallel systems, the impact of communication delays on their efficiency and on overall execution time. Paper focuses is on finite algorithms for solving systems of linear equations, namely the matrix manipulation (Gauss elimination method, GEM). Algorithms are designed for architectures with shared memory (open multiprocessing, openMP), distributed-memory (message passing interface, MPI) and for their combination (MPI + openMP). The properties of the algorithms were analytically determined and they were experimentally verified. The conclusions are drawn for theory and practice.

• Journal of Advanced Marine Engineering and Technology
• /
• 제37권3호
• /
• pp.300-306
• /
• 2013

This paper presents a new method for constructing bilingual lexicons through a pivot language. The proposed method is adapted from the context-based approach, called the standard approach, which is well-known for building bilingual lexicons using comparable corpora. The main difference between the standard approach and the proposed method is how to represent context vectors. The former is to represent context vectors in a target language, while the latter in a pivot language. The proposed method is very simplified from the standard approach thereby. Furthermore, the proposed method is more accurate than the standard approach because it uses parallel corpora instead of comparable corpora. The experiments are conducted on a language pair, Korean and Spanish. Our experimental results have shown that the proposed method is quite attractive where a parallel corpus directly between source and target languages are unavailable, but both source-pivot and pivot-target parallel corpora are available.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 추계학술대회 논문집
• /
• pp.344-349
• /
• 2005

This paper presents a geometrical error analysis of wheel curve generation method for micro aspheric surface machining using parallel grinding method. In aspheric grinding, wheel wear in process is crucial parameter for profile error of the ground surface. To decrease wheel weal parallel grinding method is adopted. Wheel and work piece (Tungsten carbide) contact point changes during machining process. In truing process of the wheel radius is determined by the angle and distance between wheel and truer. Wheel radius error is predominantly affected by vertical deviation between the wheel rotation center and the truer center Simulation for vertical error and wheel radius error shows same tendency that expected by geometrical analysis. Experimental results show that the analysis of curve generation method matches with simulations and wheel radius errors.

• 정보처리학회논문지:소프트웨어 및 데이터공학
• /
• 제12권5호
• /
• pp.207-216
• /
• 2023

본 연구에서는 압축 해제 호환성을 갖춘 병렬 처리 Deflate 압축 알고리즘을 구현하기 위하여 병렬 압축 및 압축 해제에 필수적인 정보를 복수의 비 압축 블록(Non-Compression Block)내의 버려지는 영역(Disposed Bit Area)에 저장하는 방식으로 구성한 컨트롤 헤더를 삽입하는 새로운 방식을 제안하였다. 이를 통해 기존 압축 해제 프로그램과 완벽한 호환성을 유지하면서도 병렬 압축 및 병렬 압축 해제가 가능하도록 하였다. 또한 순차 처리방식 대비 압축 시간을 최대 71.2% 절감하였고 병렬 압축해제 시간을 65.7%까지 절감하였다. 특히 Deflate 알고리즘의 구조적 제약으로 인해 병렬 압축 해제는 불가능하다고 알려져 있으나, 제안하는 방식을 탑재한 디코더로 알고리즘 수준에서 고속의 병렬 압축 해제가 가능하고, 호환성을 유지하여 동일한 압축 데이터를 기존의 압축 해제 프로그램으로도 정상적 압축 해제가 가능함을 확인하였다.