• The KIPS Transactions:PartA
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• v.16A no.1
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• pp.9-16
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• 2009

Because Grid system consists of heterogenous computing resources, which are distributed on a wide scale, it is impossible to efficiently execute applications with scheduling algorithms of a conventional parallel system that, in contrast, aim at homogeneous and controllable resources. To suggest an algorithm that can fully reflect the characteristics of a grid system, our research is focused on examining the type of information used in current scheduling algorithms and consequently, deriving factors that could develop algorithms further. The results from the analysis of these algorithms not only show that static information of resources such as capacity or the number of processors can facilitate the scheduling algorithms but also verified a decrease in efficiency in case of utilizing real time load information of resources due to the intrinsic characteristics of a grid system relatively long computing time, and the need for the means to evade unfeasible resources or ones with slow processing time. In this paper, we propose a new algorithm, which is revised to reflect static information in the logic of WQR(Workqueue Replication) algorithms and show that it provides better performance than the one used in the existing method through simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.72-81
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• 2014

Recently, because of irregular power demand, we have suffered from an electric power shortage. The necessity of the adoption of smart grid which makes effective supply of power by using the two-way communication across the grid between the customers and electric energy providers is growing more and more. If smart grid set up in our country, the third-parties which provide services to customer using the information acquired from smart grid, might be revved up. In this paper, we suggest a methodology how classify the types of family by analysing an power consumption pattern using data mining technique. To make a classifier for categorizing the household types, we need power consumption data and their family type. However, it is hard to get both of them. Therefore we develop the simulator that generates power consumption patterns of the household and classify the types of family. Also, we present a potential for application services such as customized services for a specific family or goods marketing.

• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1119-1126
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• 2021

Spacer grid with mixing vane had been widely used in nuclear reactor core. One of the main feather of spacer grid with mixing vane was that strong swirl flow was formed after the spacer grid. The swirl flow not only changed the bubble generation in the near wall field, but also affected the bubble behaviors in the center region of the subchannel. The interaction between bubble and the swirl flow was one of the basic phenomena for the two phase flow modeling in fuel assembly. To obatin better understanding on the bubble behaviors in swirl flow, full three dimension numerical simulations were conducted in the present paper. The swirl flow was assumed in the cylindral calculation domain. The bubble interface was captured by Volume Of Fluid (VOF) method. The properties of saturated water and steam at different pressure were applied in the simulation. The bubble trajectory, motion, shape and force were obtained based on the bubble parameters captured by VOF. The simulation cases in the present study included single bubble with different size, at different angular velocity conditions and at different pressure conditions. The results indicated that bubble migrated to the center in swirl flow with spiral motion type. The lateral migration was mainly related to shear stress magnitude and bubble size. The bubble moved toward the center with high velocity when the swirl magnitude was high. The largest bubble had the highest lateral migration velocity in the present study range. The effect of pressure was small when bubble size was the same. The prelimenery simulation result would be beneficial for better understanding complex two phase flow phenomena in fuel assembly with spacer grid.

• Tunnel and Underground Space
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• v.18 no.6
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• pp.427-435
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• 2008

In this paper, review was made for the excavation method and optimum bench length for unstable tunnel face in case of rock classification type V in order to make the best use of in-situ bearing capacity. 3D FEM analyses were performed to investigate the influences on the tunnel face and adjacent area with regard to the pattern and number of bolts when face bolts were used as a supplementary measure. As a result of this study, full section excavation method with sub-bench is effective in reducing the displacement greatly due to early section closure. Displacement-resistant effects in accordance with the bolting patterns are grid type, zig-zag type and then circular type in order of their effect. And horizontal extrusion displacement of tunnel face reduces as the number of bolts increase. A grid type face bolt covering $1.5m^2$ of tunnel face could secure the face stability in case of full section excavation method with sub-bench.

• Journal of the Korean Institute of Navigation
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• v.17 no.3
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• pp.77-83
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• 1993

The goal of this research is to get a measuring system for absorption characteristics over the frequency band with 30MHz to 1, 000MHz concerning the ferrite electromagnetic wave absorbers, for example, grid-type and sintered flat type, etc. It is, however, very difficult to measure the absorption characteristics as in low frequency as in 30 MHz. In this research, therefore, we propose a standing wave method using parallel striplines, fabricate the measuring system, and measure the characteristic of ferrite microwave absorbers using the proposed mea-suring system.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.2
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• pp.222-228
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• 2014

As tightened the grid connection related regulation for a distributed power generation Japan, islanding of the distributed power generation should be detected more rapidly. In this paper, it is introduced the development tendency of sliding mode frequency shift type anti-islanding technology in Japanese companies.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1999.06a
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• pp.99-104
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• 1999

화재 진압시스템 중 가장 대표적이고 많이 사용되는 설비는 스프링클러 시스템이다. 국내에 설치되고있는 스프링클러 시스템은 많은 문제점을 가지고 있으며 특히 배관방식과 설계부분이 그러하다. 지금까지의 국내의 스프링클러 시스템 설계는 규약배관방식만으로 이루어졌으며, 최근에 수리계산 방식의 인정이 법제화되어 사용이 늘어날 전망이지만, 이미 선진외국은 오래 전부터 수리계산방식을 사용하고 있으며, 급속히 발전되고있는 컴퓨터 프로그램을 이용한 수리계산 설계를 시행하고 있다. 특히 선진국에서는 국내에서는 사용하지 않고 있는 격자배관 방식(Gird System)을 사용하고 있는데 이는 컴퓨터 프로그램에 의한 설계로만 가능하다. (중략)

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1182-1183
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• 2008

In this paper, we develop PCS for doubly-fed induction-type wind generator(DFIG). PCS consists of a converter set and a controller. PCS controls the active power of wind generator and the reactive power of wind turbine system according to rotating speed, instantaneous power, grid quality, and order by transmission system operator.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.6
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• pp.203-211
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• 1984

MOS silicon solar cells have been developed using the fixed (interface) charge inherent to thermally oxidized silicon to induce an n-type inversion layer in 1-10 ohm-cm p-type silicon. Higher collection efficiencies are predicted than for diffused junction cells. Without special precautions a conversion efficiency of 14.2% is obtained. A MOS silicon solar cell is described in which an inversion layer forms the active area which is then contacted by means of a MOS grid. The highest efficiency is obtained when the resistivity of the substrate is high.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1356-1358
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• 2003

This paper describes the control of grid connected transformerless type PV power conditioning system, which is simple and more efficient than the usual transformer type system. With the modeling and analysis of power system, the validity of control strategy is well verified through the simulation and experimental results.