• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권1호
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• pp.117-135
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• 2016

Performance enhancement is one of the most important issues in high performance distributed computing systems. In such computing systems, online users submit their jobs anytime and anywhere to a set of dynamic resources. Jobs arrival and processes execution times are stochastic. The performance of a distributed computing system can be improved by using an effective load balancing strategy to redistribute the user tasks among computing resources for efficient utilization. This paper presents a multi-class load balancing strategy that balances different classes of user tasks on multiple heterogeneous computing nodes to minimize the per-class mean response time. For a wide range of system parameters, the performance of the proposed multi-class load balancing strategy is compared with that of the random distribution load balancing, and uniform distribution load balancing strategies using simulation. The results show that, the proposed strategy outperforms the other two studied strategies in terms of average task response time, and average computing nodes utilization.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전력기술부문
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• pp.42-45
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• 2001

The islanding protection for distributed resources (DR) becomes an important and emerging issue in power system protection since the distributed generator installations are rapidly increasing and most of the installed systems are interconnected with distribution network. In order to avoid the negative impacts on distributed network resulting from islanding operations of DR, it is necessary to detect the loss of mains (LOM) effectively. This paper presents a new LOM detection method using the rate of change in total harmonic distortion (THD) of current. The proposed method effectively detects LOM of the DR unit operating in parallel with the distribution network. We also verified the efficiency of the proposed method using the radial distribution network of IEEE 34 bus model.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(1)
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• pp.55-56
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• 2005

• Journal of Electrical Engineering and Technology
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• 제7권6호
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• pp.834-844
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• 2012

Nonlinear electronic loads draw harmonic currents from the power grids that can cause energy loss, miss-operation of power equipment, and other serious problems in the power grids. This paper proposes a harmonic compensation method using multiple distributed resources (DRs) such as small distributed generators (DGs) and battery energy storage systems (BESSs) that are integrated to the power grids through power inverters. For harmonic compensation, DRs should inject additional apparent power to the grids so that certain DRs, especially operated in proximity to their rated power, may possibly reach their maximum current limits. Therefore, intelligent coordination methods of multiple DRs are required for efficient harmonic current compensation considering the power margins of DRs, energy cost, and the battery state-of-charge. The proposed method is based on fuzzy multi-objective optimization so that DRs can cooperate with other DRs to eliminate harmonic currents with optimizing mutually conflicting multi-objectives.

• Korean Journal of Hydrosciences
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• 제5권
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• pp.1-16
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• 1994

In this paper distributed models for simulating spatially and temporally varied moving storm in a watershed were developed. The complete simulation in a watershed is achieved through two sequential flow simulations which are overland flow simulation and channel network flow simulation. Two dimensional continuity equation and momentum equation of kinematic approximation were used in the overland flow simulation. On the other hand, in the channel network simulation two types of governing equations which are one dimensional continuity and momentum equations between two adjacent sections in a channel, and continuity and energy equations at a channel junction were applied. The finite difference formulations were used in the channel network model. Macks Creek Experimental Watershed in Idaho, USA was selected as a target watershed and the moving storm on August 23, 1965, which continued from 3:30 P.M. to 5:30 P.M., was utilized. The rainfall intensity fo the moving storm in the watershed was temporally varied and the storm was continuously moved from one place to the other place in a watershed. Furthermore, runoff parameters, which are soil types, vegetation coverages, overland plane slopes, channel bed slopes and so on, are spatially varied. The good agreement between the hydrograph simulated using distributed models and the hydrograph observed by ARS are Shown. Also, the conservations of mass between upstreams and downstreams at channel junctions are well indicated and the wpatial and temporal vaiability in a watershed is well simulated using suggested distributed models.

• 한국컴퓨터정보학회논문지
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• 제11권4호
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• pp.69-75
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• 2006

과학 기술이 발전함에 따라 대량의 정보를 처리하기 위해 대두된 인터넷을 기반으로 하는 분산 컴퓨팅 환경은 대규모의 독립된 자원을 공유하여 과학 연구와 같은 문제를 해결하기 위한 구축된 환경이므로, 사용자 작업을 효율적으로 할당하기 위한 스케줄링 알고리즘이 필요하다. 현재까지 여러 스케줄링 알고리즘이 연구되어 왔지만, 대부분 피어의 자율성을 고려하지 않는 문제점을 가지고 있다. 본 논문에서는 이러한 문제점을 해결하기 위하여 인터넷기반 분산 컴퓨팅 환경에서의 피어 가용길이 예상 기법을 제안하였다. 또한 인터넷기반 분산 컴퓨팅환경에서 사용되는 SRTFIT 알고리즘에 적용하여, 시뮬레이션을 통하여 제안된 기법이 단순한 예상기법보다 성능이 뛰어남을 보였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2002년도 학술발표회 논문집(I)
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• pp.221-226
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• 2002

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2001년도 학술발표회 논문집(I)
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• pp.230-235
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• 2001

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(1)
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• pp.793-794
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• 2005

• 한국수자원학회논문집
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• 제34권2호
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• pp.131-140
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• 2001

본 연구는 분포형 개념에 기초한 USLE(Universal Soil Loss Equation)의 매개변수의 산정방법과 유역에서 발생한 유사전달률을 중심으로 수행되었다. 그리드를 이용한 분포형 개념의 모형은 경사가 가장 급한 방향으로 한 그리드에서 다른 그리드로 유사를 추적할 수 있다. 여기서는 기존에 조사된 경기도 지역에 위치한 10개의 농업용 저수지의 토사유출량과 유역의 물리적인 특성을 수집하여 연구에 이용하였다. 한 그리드의 유사전달률은 그 그리드의 숲이나 토사이동을 방해하는 면적비와 관계가 있다고 정의하고 $C_1$이라는 비례상수를 도입하였다. 8개 저수지에 대하여 모형을 보정하고 나머지 2개 저수지에 대하며 검정을 실시하였으며 유역의 물리적인 특성과 $C_1$과의 회귀분석을 실시하였다. 회귀분석 결과를 2개의 저수지 유역에 검정한 바 적절한 결과를 보였으며 본 연구에서 제안한 모형의 적용 가능성을 확인할 수 있었다.