• International Journal of Contents
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• 제1권1호
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• pp.40-44
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• 2005

This paper introduces region partitioning method of non-perfect nested loops with non-uniform dependences. This kind of loop normally can't be parallelized by existing parallelizing compilers and transformations. Even when parallelized in rare instances, the performance is very poor. Based on the Convex Hull theory which has adequate information to handle non-uniform dependences, this paper proposes an enhanced region partitioning method which divides the iteration space into minimum parallel regions where all the iterations inside each parallel region can be executed in parallel by using variable renaming after copying.

• 한국경영과학회지
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• 제19권3호
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• pp.219-233
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• 1994

A fixed k-coloring problem is introduced and dealt with by efficient heuristic algorithms. It is shown that the problem can be transformed into the graph partitioning problem. Initial coloring and improving methods are proposed for problems with and with and without the size restriction. Algorithm Move, LEE and OEE are developed by modifying the Kernighan-Lin's two way uniform partitioning procedure. The use of global information in the selection of the node and the color set made the proposed algorithms superior to the existing method. The computational result also shows that the superiority does not sacrifice the time demand of the proposed algorithms.

• Journal of Communications and Networks
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• 제8권1호
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• pp.13-20
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• 2006

In cellular mobile communications, how to achieve optimum system capacity with limited frequency spectrum is one of the main research issues. Many dynamic channel assignment (DCA) schemes have been proposed and studied to allocate the channels more efficiently, thus, the capacity of cellular systems is improved. Reuse partitioning (RP) is another technique to achieve higher capacity by reducing the overall reuse distance. In this paper, we present a network-based DCA scheme with the implementation of RP technique, namely dynamic reuse partitioning with interference information (DRP-WI). The scheme aims to minimize the effect of assigned channels on the availability of channels for use in the interfering cells and to reduce their overall reuse distances. The performance of DRP-WI is measured in terms of blocking probability and system capacity. Simulation results have confirmed the effectiveness of DRP-WI scheme. Under both uniform and non-uniform traffic distributions, DRP-WI exhibits outstanding performance in improving the system capacity. It can provide about 100% capacity improvement as compared to conventional fixed channel assignment scheme with 70 system channels.

• Steel and Composite Structures
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• 제33권2호
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• pp.163-180
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• 2019

A semi analytical method is employed to analyze free vibration characteristics of uniform and stepped functionally graded circular cylindrical shells under complex boundary conditions. The analytical model is established based on multi-segment partitioning strategy and first-order shear deformation theory. The displacement functions are handled by unified Jacobi polynomials and Fourier series. In order to obtain continuous conditions and satisfy complex boundary conditions, the penalty method about spring technique is adopted. The solutions about free vibration behavior of functionally graded circular cylindrical shells were obtained by approach of Rayleigh-Ritz. To confirm the dependability and validity of present approach, numerical verifications and convergence studies are conducted on functionally graded cylindrical shells under various influencing factors such as boundaries, spring parameters et al. The present method apparently has rapid convergence ability and excellent stability, and the results of the paper are closely agreed with those obtained by FEM and published literatures.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.115-115
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• 2020

Water network partitioning (WNP) is an initiative technique to divide the original water distribution network (WDN) into several sub-networks with only sparse connections between them called, District Metered Areas (DMAs). Operating and managing (O&M) WDN through DMAs is bringing many advantages, such as quantification and detection of water leakage, uniform pressure management, isolation from chemical contamination. The research of WNP recently has been highlighted by applying different methods for dividing a network into a specified number of DMAs. However, it is an open question on how to determine the optimal number of DMAs for a given network. In this study, we present a method to divide an original WDN into DMAs (called Clustering) based on community structure algorithm for auto-creation of suitable DMAs. To that aim, many hydraulic properties are taken into consideration to form the appropriate DMAs, in which each DMA is controlled as uniform as possible in terms of pressure, elevation, and water demand. In a second phase, called Sectorization, the flow meters and control valves are optimally placed to divide the DMAs, while minimizing the pressure reduction. To comprehensively evaluate the WNP performance and determine optimal number of DMAs for given WDN, we apply the framework of multiple-criteria decision analysis. The proposed method is demonstrated using a real-life benchmark network and obtained permissible results. The approach is a decision-support scheme for water utilities to make optimal decisions when designing the DMAs of their WDNs.

• 전자공학회논문지CI
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• 제45권5호
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• pp.180-191
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• 2008

적응적 랜덤 테스팅 (Adaptive Random Testing, ART)은 입력 도메인 내의 오류 패턴을 순수 랜덤 테스팅 (Random Testing, RT)보다 좋은 효율로 찾아내기 위해 고안된 테스트 케이스 선택 알고리즘이다. 대표적인 ART 기법인 거리 기반 ART (Distance-based ART, D-ART)와 제한 영역 기반 ART (Restricted Random Testing, RRT) 둥은 좋은 성능을 보이기는 하지만, 테스트 케이스 선택에 필요한 많은 양의 거리 계산으로 인한 느린 테스트 케이스 생성과 거리 기반 방식의 사용으로 인한 테스트 케이스 분포의 불균일성이라는 단점을 가진다. 반복 분할 기반 ART (ART through Iterative Partitioning, IP-ART)는 입력 도메인을 반복 분할하는 방식을 통해 D-ART와 RRT가 가진 계산 부하를 크게 감소시켰다. 하지만 IP-ART의 경우에도 테스트 케이스 분포 문제는 여전히 존재하여 기법의 확장 적용에 대한 장애 요소로 작용하고 있다. 따라서 본 논문에서는 이와 같은 IP-ART의 단점 완화 및 성능 개선을 위한 방법을 제안하고, 실험을 통해 평균 9% 정도의 성능 향상을 확인하였다.

• Journal of electromagnetic engineering and science
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• 제15권1호
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• pp.14-19
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• 2015

In multicellular wireless networks, intercell interference limits system performance, especially cell edge user performance. One promising approach to solve this problem is the intercell interference coordination (ICIC) scheme. In this paper, we propose a new ICIC scheme based on a resource partitioning approach to enhance cell edge user performance in a wireless multicellular system. The most important feature of the proposed scheme is that the algorithm is performed at each base station in a distributed manner and therefore minimizes the required information exchange between neighboring base stations. The proposed scheme has benefits in a practical environment where the traffic load distribution is not uniform among base stations and the backhaul capacity between the base stations is limited.

• International Journal of Contents
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• 제2권4호
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• pp.8-11
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• 2006

This paper describes several loop partitioning techniques such as loop splitting method by thresholds and Polychronopoulos' loop splitting method for exploiting parallelism from single loop which already developed. We propose improved loop splitting method for maximizing parallelism of single loops with non-constant dependence distances. By using the distance for the source of the first dependence, and by our defined theorems, we present generalized and optimal algorithms for single loops with non-uniform dependences. The algorithms generalize how to transform general single loops into parallel loops.

• International Journal of Contents
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• 제3권3호
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• pp.15-19
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• 2007

We review some loop partitioning techniques such as loop splitting method by thresholds and Polychronopoulos' loop splitting method for exploiting parallelism from single loop which already developed. We propose improved loop splitting method for maximizing parallelism of single loops with non-constant dependence distances. By using the iteration and distance for the source of the first dependence, and by our defined theorems, we present generalized and optimal algorithms for single loops with non-uniform dependences. The algorithms generalize how to transform general single loops with one dependence as well as with multiple dependences into parallel loops.

• 한국정보과학회논문지:데이타베이스
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• 제31권2호
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• pp.122-131
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• 2004

이전의 연구들에서 제안된 많은 색인 방법들은 저차원과 동적인 환경을 가정하고 제안되었다. 그러나 최근의 많은 데이타베이스 응용분야들은 대용량, 고차원 그리고 정적인 환경에 대한 처리를 요구하고 있다. 따라서 기존의 저차원이고 동적인 환경에서 제안되었던 색인 구축 전략들은 특히 데이타 및 공간 분할에 있어서 새로운 환경에 잘 적응하지 못한다. 본 연구에서 우리는 이러한 사실들을 지적하였고, 새로운 환경에 적응하는 색인 구축 시 적용되는 새로운 분할 전략을 성능 모델에 근거하여 제안하였다. 우리의 접근 방법은 기본적으로 정적인 환경에서 색인 구축에 사용되는 패킹이라는 기법을 적용하였다. 그리고 고차원 환경에서 질의 성능의 기대 값을 제시하는 민코프스키-합 비용모델에 대한 관찰 결과를 이용하였다. 이러한 것들에 바탕을 두어 우리는 데이타 및 공간을 균등하게 분할하는 것보다 불균등하게 분할하는 것이 좋을 것이라는 예측을 비용 모델에 대한 관찰 결과로써 도출하였다. 그리고 이러한 결과를 이용한 불균등 분할 방법과 성능 모델들을 제시하였다. 이 연구의 결론으로서 균등 분할 방법보다 불균등 분할 방법이 고차원 환경에서 더 효율적인 방법임을 성능 모델 및 실험을 통하여 보여주었다. 그리고, 어떻게 불균등하게 분할하는 것이 좋은지에 대한 명확한 계량적 기준들을 제시하였다.