• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.8
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• pp.133-141
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• 2010

MG(Microgrid) is a small power supply system located on-site that can supply both the electricity and the hot-water simultaneously. Engineering S/W is requested to construct Microgrids economically. We developed Engineering S/W that can combine DERs (Distributed Energy Resources) most economically using the linear programming and estimate of the economic. Developed S/W was programed using GAMS(General Algebraic Modeling System) and it is composed of the optimal DER combination module and forecasting module of renewable energy's output. We embody it based on MS Excel considering the user's convenience and we show its validity through a case study. We think that developed S/W will be very useful for planning MGs and energy supply.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.3
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• pp.143-150
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• 2012

A simulation methodology and corresponding program based on it is to be discussed for analyzing the effects of the networking operation of existing DHC system in connection with CHP system on-site. The practical simulation for arbitrary areas with various building compositions is carried out for the analysis of operational features in both systems, and the various aspects of thermal energy grids with connecting operation are highlighted through the detailed assessment of predicted results. The intrinsic operational features of CHP prime movers, gas engine, gas turbine etc., are effectively implemented by realizing the performance data, i.e. actual operation efficiency in the full and part loads range. For the sake of simplicity, a simple mathematical correlation model is proposed for simulating various aspects of change effectively on the existing DHC system side due to the connecting operation, instead of performing cycle simulations separately. The empirical correlations are developed using the hourly based annual operation data for a branch of the Korean District Heating Corporation (KDHC) and are implicit in relation between main operation parameters such as fuel consumption by use, heat and power production. In the simulation, a variety of system configurations are able to be considered according to any combination of the probable CHP prime-movers, absorption or turbo type cooling chillers of every kind and capacity. From the analysis of the thermal network operation simulations, it is found that the newly proposed methodology of mathematical correlation for modelling of the existing DHC system functions effectively in reflecting the operational variations due to thermal energy grids with connecting operation. The effects of intrinsic features of CHP prime-movers, e.g. the different ratio of heat and power production, various combinations of different types of chillers (i.e. absorption and turbo types) on the overall system operation are discussed in detail with the consideration of operation schemes and corresponding simulation algorithms.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.12
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• pp.1458-1467
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• 1999

VLSI 공정 기술이 발달하면서 이웃한 전선 간의 간격이 점점 더 가까워 지고 있으며, 그에 따라 인접 전선 간의 혼신 문제가 심각해지고 있다. 본 논문에서는 3층 그리드 채널 배선에 적용 가능한 혼신을 최소화시키는 배선층 할당 방법을 제안한다. 이 방법은 선형 의사 불린 최적화 기법에 맞도록 고안되었으며, 적절한 변수 선택 휴리스틱과 상한값 추정 방법을 통하여 최적의 결과를 짧은 시간 안에 찾아낸다. 실험 결과를 통하여, 일반적인 0/1 정수 선형 프로그래밍 기법과 비교하여 성능과 수행시간 면에서 우수함을 보인다. Abstract Current deep-submicron VLSI technology appears to cause crosstalk problem severe since it requires adjacent wires to be placed closer and closer. In this paper, we deal with a horizontal layer assignment problem for three layer HVH channel routing to minimize coupling capacitance, a main source of crosstalk. It is formulated in a 0/1 integer linear programming problem which is then solved by a linear pseudo boolean optimization technique. Experiments show that accurate upper bound estimation technique effectively reduces crosstalk in a reasonable amount of running times.

• Journal of radiological science and technology
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• v.41 no.2
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• pp.149-155
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• 2018

Quantitative analysis was performed to confirm that moire artifact was removed without loss of image when using grid suppression software in the diagnosis of micro lesions. we showed that grid suppression images can be morphologically different from original images as they are significantly lower than those of the optimized grid in the similarity analysis with reference images in mammographic phantom images. We were confirmed that images of microcalcification with smaller signal than noise were lost because the pixel values of all lesions increased significantly after the grid suppression, The change in contrast using the NORMI 13 X-ray test phantom was reduced to 30% of the reference image, This result was significantly lower than the 90% when using the optimized grid. In conclusion, the use of grid suppression software in clinical images should be carefully considered because of the possibility of misdiagnosis due to micro lesion loss and morphological changes.

• Information and Communications Magazine
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• v.31 no.6
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• pp.69-74
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• 2014

기후변화에 적극 대처하여 지속적이고 안정적인 용수 공급을 위해 기존의 용수 생산 공급망에 정보통신 기술(Information & Communication Technologies, ICT)을 접목한 지능형 물관리를 위해 '스마트 워터 그리드(smart water grid)'를 구축하고자 하는 다양한 노력이 최근 들어 지속되고 있다. 즉, 스마트 워터 그리드는 기존의 수자원 관리 시스템의 한계를 극복하기 위해 첨단 정보통신기술을 이용하는 고효율의 차세대 인프라 시스템으로 다양한 수원을 활용하고 물을 효율적으로 배분 관리 운송하여 수자원의 불균형을 해소하고, 첨단 센서 네트워크를 이용해 실시간으로 수자원망의 안정성을 모니터링하는 등 용수관리 전분야에 걸쳐 양방향 실시간으로 용수정보를 감시 대응하여 용수관리와 에너지 효율의 최적화된 메가시티(mega-city)에 적합한 지능형 물관리가 가능할 것으로 예상되는 시스템이다. 따라서 본 고에서는 선진화된 상수도시스템 운영을 위해서는 현장설비의 관측값을 감시하고 제어하는 시스템에서, 운영 방식이 변경될 때마다 운영 변수간의 인과관계를 분석하고 예측할 수 있는 시뮬레이션 기능이 탑재된 상수도 운영시스템이 요구되고 있는 실정에서 용수공급 시스템의 운영 상황을 모의할 수 있는 모형 개발 및 용수공급시스템의 운영룰 모의 및 운영의사결정에 적용할 수 있는 다중수원 워터루프 시스템과 운영관리할 수 있는 S/W를 개발 내용을 소개하였다.

• Journal of Korea Multimedia Society
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• v.9 no.11
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• pp.1410-1420
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• 2006

In this paper, a replica update propagation method for cost optimization of request forwarding in the Grid database is proposed,. In the Grid database, the data is replicated for performance and availability. In the case of data update, update information is forwarded to the neighbor nodes to synchronize with the others replicated data. There are two kinds of update propagation method that are the query based scheme and the log based scheme. And, only one of them is commonly used. But, because of dynamically changing environment through property of update query and processing condition, strategies that using one propagation method increases transmission cost in dynamic environment. In the proposed method, the three classes are defined from two cost models of query and log based scheme. And, cost functions and update propagation method is designed to select optimized update propagation scheme from these three classes. This paper shows a proposed method has an optimized performance through minimum transmission cost in dynamic processing environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9B
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• pp.1407-1415
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• 2010

In recent years, the smart grid technique for maximizing the energy efficiency of power networks has received a great deal of attentions. In particular, the Demand Response is a core technology differentiated from the present power network under the smart grid paradigm. To minimize the electric cost and maximize users' satisfaction, this paper proposes a unique scheduling algorithm derived by using optimization where the characteristics of various home appliances are taken into account. For this goal, we represent mathematical consumption patterns of the electric loads and propose the optimal scheduling scheme based on the importance factor of each device during one day. In the simulation results, we demonstrate the effectiveness of the proposed algorithm in the viewpoint of the minimal electric costs utilizing real statistical figures.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.4
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• pp.71-81
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• 2010

In grid system, Task scheduling based on list scheduling models has showed low complexity and high efficiency in fully connected processor set environment. However, earlier schemes did not consider sufficiently the communication cost among tasks and the composition process of lightpath for communication in optical gird environment. In this thesis, we propose LSOG (Leveling Selection in Optical Grid) which sets task priority after forming a hierarchical directed acyclic graph (DAG) that is optimized in optical grid environment. To determine priorities of task assignment in the same level, proposed algorithm executes the task with biggest communication cost between itself and its predecessor. Then, it considers the shortest route for communication between tasks. This process improves communication cost in scheduling process through optimizing link resource usage in optical grid environment. We compared LSOG algorithm with conventional ELSA (Extended List Scheduling Algorithm) and SCP (Scheduled Critical Path) algorithm. We could see the enhancement in overall scheduling performance through increment in CCR value and smoothing network environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2063-2072
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• 2013

Smart Grid is the next-generation intelligent power grid that maximizes energy efficiency with the convergence of IT technologies and the existing power grid. It enables consumers to check power rates in real time for active power consumption. It also enables suppliers to measure their expected power generation load, which stabilizes the operation of the power system. However, there are high possibility that various kinds of security threats such as data exposure, data theft, and privacy invasion may occur in interactive communication with intelligent devices. Therefore, to establish a secure environment for responding to such security threat with the smart grid, the key management technique, which is the core of the development of a security mechanism, is required. Using a hash chain, this paper suggests a group key management mechanism that is efficiently applicable to the smart grid environment with its hierarchical structure, and analyzes the security and efficiency of the suggested group key management framework.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.258-264
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• 2018

This paper presents application of a differential search (DS) meta-heuristic optimization algorithm for optimal operation of a micro grid system. The DS algorithm simulates the Brownian-like random-walk movement used by an organism to migrate. The micro grid system consists of a wind turbine, a diesel generator, a fuel cell, and a photovoltaic system. The wind turbine generator is modeled by considering the characteristics of variable output. Optimization is aimed at minimizing the cost function of the system, including fuel costs and maximizing fuel efficiency to generate electric power. The simulation was applied to a micro grid system only. This study applies the DS algorithm with excellence and efficiency in terms of coding simplicity, fast convergence speed, and accuracy in the optimal operation of micro grids based on renewable energy resources, and we compared its optimum value to other algorithms to prove its superiority.