• 전기학회논문지P
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• 제59권1호
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• pp.100-105
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• 2010

This paper describes a capacity of distributed generation which will be interconnected at low voltage distribution systems. In order to set the capacity of distributed generation, a voltage variation of distribution system is considered. Besides, the capacity of distributed generation is classified according to a capacity of pole transformer and loads. The system constructions in this paper are analyzed by using PSCAD/EMTDC. In the immediate future, it is expected to increase the installation of New and renewable energy systems which are generally interconnected to distribution power systems in the form of distributed generations like photovoltaic system, wind power and fuel cell. So the study of this kind would be needed to limit the capacity of distributed generation.

• 한국산학기술학회논문지
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• 제13권6호
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• pp.2713-2719
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• 2012

위치를 기반으로 하는 서비스가 다양해짐에 따라 고가용성과 고확장성을 제공하기 위한 분산 데이터 스트림 처리 기법에 대한 연구가 널리 수행되고 있다. 기존 연구는 분산된 노드들에서 부하의 균형을 유지하기 위해 공간 데이터 스트림의 지리적인 특성을 고려하지 않고 있어 공간적으로 인접한 연산을 수행함에 있어 전체 시스템의 부하를 증가시키고 있다. 본 논문에서는 분산 환경의 공간 데이터 스트림을 처리하기 위해 공간 영역의 겹침을 고려한 연산배치 기법을 제안한다. 제안 기법에서는 인접한 공간 영역을 대상으로 하는 연산을 효율적으로 분리하기 위해 질의 영역이 겹치는 부분의 연산을 우선적으로 동일 노드에 분배하여 중복 영역에 대한 공유의 최대화를 보장한다.

• 한국농공학회논문집
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• 제50권2호
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• pp.19-26
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• 2008

This study has been carried out to investigate the dynamic characteristics of RC slabs. For this purpose, the 20-node solid element has been used to discretize the RC slabs into two parts of concrete and rebar. The material non-linearity considering elasto-visco plastic model and the smeared crack model have been adopted in the finite element formulation. The applied load can handle step load, load intensity of harmonic load, area of distributed load and frequency. The frequency of harmonic load has an significant effect on dynamic behaviour in terms of displacement. As the frequency is increased, the effect of load amplitude is more serious. Especially, if the frequency of harmonic load exceeds 30 Hz, it is noted that the displacement by harmonic load is greater than that by step load. In case of harmonic load, the damping effect shows no certain tendency with respect to frequency of load. In details, the damping is effective when the frequency of harmonic load is 2 Hz, but there is no consistent tendency according to damping ratio. The dynamic response when the frequency of harmonic load is 3 Hz shows same result for undamped case as well as for damped case with 5% damping ratio. It is also noted that we can get the largest deflection for damped case with 1% damping ratio. However, there is not any damping effect when the frequency of harmonic load is greater than 4 Hz.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.176-179
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• 2002

In recent years, an increasing amount of computer network research has focused on the problem of cluster system in order to achieve higher performance and lower cost. The load unbalance is the major defect that reduces performance of a cluster system that uses parallel program in a form of SPMD (Single Program Multiple Data). Also, the load unbalance is a problem of MPP (Massive Parallel Processors), and distributed system. The cluster system is a loosely-coupled distributed system, therefore, it has higher communication overhead than MPP. Dynamic load balancing can solve the load unbalance problem of cluster system and reduce its communication cost. The cluster systems considered in this paper consist of P heterogeneous nodes connected by a switch-based network. The master node can predict the average execution time of tasks for each slave node based on the information from the corresponding slave node. Then, the master node redistributes remaining tasks to each node considering the predicted execution time and the communication overhead for task migration. The proposed dynamic load balancing uses execution time prediction to optimize the task redistribution. The various performance factors such as node number, task number, and communication cost are considered to improve the performance of cluster system. From the simulation results, we verified the effectiveness of the proposed dynamic load balancing algorithm.

• 소음진동
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• 제7권1호
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• pp.91-97
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• 1997

An analysis is presented on the stability of an elastic cantilever column having the elastic restraints at its free end, carrying an added tip mass, and subjected to uniformly distributed follower forces. The elastic restraints are formed by both a translational spring and a rotatory spring. For this purpose, the governing equations and boundary conditions are derived by using Hamilton's principle, and the critical flutter loads and frequencies are obtained from the numerical evaluation of the eigenvalue functions of this elastic system. The added tip mass increases as a whole the critical flutter load of the elastic cantilever column, but the presence of its moment of inertia of mass has a destabilizing effect. The existence of the translational and rotatory springs at the free end increases the critical flutter load of the elastic cantilever column. Nevertheless, their effects on the critical flutter load are not uniform because of their coupling. The translational spring restraining the free end of the cantilever column decreases the critical flutter load by coupling with a large value of tip mass, while by coupling with the moment of inertia of tip pass its effect on the critical flutter load is contrary. The rotatory spring restraining the free end of the cantilever column increases the critical flutter load by coupling with the tip mass, but decreases it by coupling with the moment of inertia of the tip mass.

• 한국컴퓨터정보학회논문지
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• 제11권1호
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• pp.1-10
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• 2006

부하재분배 방법은 컴퓨터시스템에서 중요한 요소이다. 수신자 개시 부하재분배 알고리즘에서는 전체시스템이 저부하일 때 수신자(저부하 프로세서)가 부하를 이전받기 위해 송신자(과부하 프로세서)를 발견할 때까지 불필요한 이전 요청 메시지를 계속 보내게 된다. 따라서 이같은 상황에서는 과부하 상태인 송신자 프로세서로부터 승인 메시지를 받기까지 불필요한 프로세서간 통신으로 인하여 프로세서의 이용률이 저하되고, 타스크 처리율이 낮아지는 문제점이 발생한다. 본 논문에서는 이질형 분산 시스템에서의 동적 부하재분배를 위해 유전 알고리즘을 기반으로 하는 접근 방법을 제안한다. 이 기법에서는 불필요한 요청메시지를 줄이기 위해 요청 메시지가 전송될 프로세서들이 제안된 유전 알고리즘에 의해 결정된다.

• 한국농공학회지
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• 제43권4호
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• pp.89-96
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• 2001

In this study non-linear finite element analysis of dynamic response of steel arch under partially distributed dynamic load was discussed. Material and geometric non-linearities were included in finite element formulation and steel behavior was modeled with Von Mises yield criteria. Either radial or vertical dynamic load was dealt in numerical examples. Normal arch and arch with maximum shape imperfection of L/11,000 were studied. The analysis results showed that maximum displacement at the center of arch was occurred when 70% of arch span was loaded. The maximum displacement at a quarter of arch span was occurred when 50% of arch span was loaded and the displacement was larger than that of center of arch. Ratio of arch rise to arch span within 0.2∼-.3 seems to be appropriate for arch under radial or vertical load.

• 조명전기설비학회논문지
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• 제19권2호
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• pp.100-106
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• 2005

본 논문에서는 분산형 전원을 포함하는 배전계통을 위한 3상 조류계산 프로그램에 대하여 소개한다. 배전계통의 조류계산을 위하여 각 상간에 존재하는 불평형을 모두 고려할 수 있도록 계통 내 설비들의 모델을 선정하였으며, 전력방정식이나 측정함수 등도 새로 유도하였다. 본 논문을 통해 개발된 조류계산 프로그램은 다양한 크기와 형태의 시험계통에 대해 사례연구를 시행함으로써 알고리즘의 타당성 및 프로그램의 수렴성을 검증하였다.

• Structural Engineering and Mechanics
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• 제87권1호
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• pp.95-106
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• 2023

This paper investigates the dynamic response of a functionally graded material (FGM) coated half-plane excited by distributed time harmonic loading. Three types of typical distributed surface loads, including uniform load, Hertz load, and square-root singular load, are considered. The mass density and elastic modulus of the FGM coating are supposed to be described by the exponential function. The material damping is modelled by a linearly hysteretic damping which is expressed by a complex modulus in the time harmonic motion. Using Fourier integral transform technique and numerical integral method, the effects of the excitation frequency, gradient index, damping, and load type on the dynamic stresses and displacements are discussed.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제21권8호
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• pp.543-548
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• 2015

최근 소셜 미디어의 성장과 디지털 기기의 활용이 증가함에 따라 기하급수적으로 데이터가 급증하고 있다. 기존 디스크 기반 분산 파일 시스템은 I/O 처리 비용 및 병목 현상으로 인해 데이터 처리나 데이터 접근 성능에 한계가 발생한다. 이러한 문제점을 해결하기 위해 메모리에 데이터를 관리하는 캐시 기법이 활용되고 있다. 본 논문에서는 분산 메모리 환경에서 부하 분산을 처리하기 위한 캐시 관리 기법을 제안한다. 제안하는 기법은 노드의 메모리의 크기가 서로 상이한 환경에서 메모리 크기에 따라 데이터를 분배하고 노드의 부하가 발생할 경우 핫 데이터를 재분배한다. 또한, 캐시 항목의 재사용 가능성, 사용 빈도수, 접근 시간을 고려한 캐시 교체 기법을 제안한다. 성능 평가를 통해 제안하는 분산 캐시 기법이 기존에 캐시 관리 기법에 비해 우수함을 입증한다.