• Journal of Electrical Engineering and Technology
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• 제11권6호
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• pp.1582-1589
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• 2016

In this paper the integration of Distributed Generation (DG) in radial distribution system is investigated by computing the optimal site and size of DG to be placed. An analytical expression based on equivalent current injection has been derived by utilizing topological structure of radial distribution system to find optimal size of DG to minimize losses. In the presented formulation, the optimal DG placement is obtained without repeatedly computing the load flow. The proposed formulation can be used to find the optimal size of all types of DGs namely Type-I, Type-II, Type-III and Type-IV DGs. The investigations are carried out on IEEE 33-bus and 69-bus radial distribution systems. The optimal DG placement results into reduction in active and reactive power losses and improvement in voltage profile of the buses.

• 신재생에너지
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• 제19권3호
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• pp.1-12
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• 2023

This study aims to evaluate the optimal size of the hydrogen facility to be installed in a zero-energy district in terms of load matching and facility efficiency. A mismatch between energy generation and consumption is a common occurrence in zero-energy districts. This mismatch adversely effects the energy grid. However, using an energy carrier such as hydrogen can solve this problem. To determine the optimal size of hydrogen fuel cells to be used on-site, simulation of hydrogen installation is required at both district-and building- levels. Each case had four operating schedules. Therefore, we evaluated eight scenarios in terms of load matching, heat loss, and facility operational efficiency. The results indicate that district-level installation of hydrogen facilities enables more efficient energy use. Additionally, based on the proposed model, we can calculate the optimal size of the hydrogen facility.

• 한국측량학회지
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• 제33권5호
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• pp.427-436
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• 2015

본 연구는 건기에 1일 50ton 규모의 지하수 양수를 목적으로 하는 소규모 인공함양(Artificial Recharge) 지하저수지 설치를 위한 적지선정 기법을 모색한다. 먼저 수리모델 실험결과 다양한 인자에 부응하는 적지 후보지 형상을 정의하고, 주입과 양수모델링 실험을 수행하여 적합한 양수효율을 산정하였다. 다음으로는 최적 후보지 선정을 위하여 각종 지형공간정보를 처리하여 GIS(Geographic Information System) DB를 구축하였다. 구체적으로 설명하면, 5m 격자의 DEM(Digital Elevation Model)으로부터 유역분할 영상을 생성하여 적지의 최소단위로 정의하며 경사도를 이용하여 일정기간의 대수층 저류 기간을 확보하기 위한 적정 수두구배를 결정한다. 최종적으로 유역 분할 영상과 경사도, 정사영상 및 DEM 자료 등을 종합 이용하여 최적 형상에 준하는 영역을 인공함양의 최종 후보지로 선정한다.

• 한국측량학회지
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• 제40권3호
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• pp.195-206
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• 2022

The primary purpose of this study was to analyze assessment factors by identifying and prioritizing live fire shooting area requirements using the AHP (Analytic Hierarchy Process) technique. Derived assessment factors for candidate sites were divided into six categories. Of these, four categories (base-to-range distance, weapon danger area, range terrain, and size) were in the realm of physical geography while the remaining two (land use and proximity to habitation) fell under the general heading of human geography. A case study was also conducted to select several alternative firing ranges using derived factors. The optimal location was analyzed by evaluating the candidate site using each assessment factor. As a result, it was found that assessment factors applying to GIS (Geographic Information System) were able to effectively analyze a suitable location for relocation of the focal training facility, taking into consideration public-safety issues, training requirements, and residents' past and likely future complaints. Through this process, it can prevent the waste of time and effort in determining an optimal location for a live fire shooing range.

• 대한안전경영과학회지
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• 제7권1호
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• pp.159-166
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• 2005

It is not difficult to see the road repairing. There are many and various machines which crush road surface. The efficiency and power of the machine depend on crushing head-shape, crushing interval, crushing load, crushing stress, machine's dropping height and roller's kind. The objective of this study is to select the optimal model among ten models of crushing machine with constraints such as crushing depth, variation, and crushed particle size. And then this paper provides the valid theoretical base on selected model. The data for this study are chosen from the site of construction in Kangnung during three months (2004. 6. 1${\~}$2004. 8. 31). The provided methodology in this paper will be fruitful not only for the selection of crushing machine but also for the aspects of construction period, cost, work efficacy according to the condition from the various sites of construction.

• 대한전자공학회논문지
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• 제27권4호
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• pp.571-579
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• 1990

A dynamic relocation algorithm for non-deterministic process graph in distributed computer systems is proposed. A method is represented for determining the optimal policy for processing a process tree. A general database query request is modelled by a process tree which represent a set of subprocesses together with their precedence relationship. The process allocation model is based on operating cost which is a function fo selection of site for processing operation, data reduction function and file size. By using expected values of parameters for non-deterministic process tree, the process graph and optimal policy that yield minimum operating cost are determined. As process is relocated according to threshold value and new information of parameters after the execution of low level process for non-deterministic process graph, the assigned state that approximate to optiaml solution is obtained. The proposed algorihtm is heuristic By performing algorithm for sample problems, it is shown that the proposed algorithm is good in obtaining optimal solution.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1318-1327
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• 2008

Geotechnical sites in urban areas may have embedded structures such as utility lines and underground concrete structures, which cause difficulties in site investigation. This study is a preliminary research to establish knowledge base for developing an optimal technique for site investigation in urban areas. Surface-wave method and resistivity survey, which are frequently adopted for non-destructive site-investigation for geotechnical sites, were investigated to characterize effects of adjacent structures. In case of surface wave method, patterns of wave propagation were investigated for typical sets of multi-layered geotechnical profiles by numerical simulation based on forward modeling theory and field experiments for small-size model tests and real-scale tests in the field. In case of resistivity survey, 3-D finite element analyses and field tests were performed to investigate effects of adjacent concrete structures. These theoretical and experimental researches for surface-wave method and resistivity survey resulted in establishing physical criteria to cause interference of adjacent structures in site investigation at urban areas.

• 한국항해항만학회지
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• 제41권1호
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• pp.17-24
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• 2017

본 연구는 신규로 건설되는 국제여객터미널의 최적 항만운영안을 제시하는 것을 목적으로 한다. 컨조인트 분석을 활용하여 최적 항만운영이 될 수 있는 대안을 분석하였다. 또한 사용자 관점과 실사업 주관입장인 인천항만공사와 인식차이 비교분석을 실시한다. 사용자 컨조인트 분석결과 '임대료 산정방식'이 신국제여객터미널 항만운영 방안에서는 가장 중요한 요인으로 도출되었다. 다음으로 자동화구축, 부지면적 순으로 분석되었다. 수준별 효용결과를 살펴보면 임대료 산정방식에서는 '국유재산법 적용방식', 자동화구축에서는 '야드장비의 자동화', 부지면적에서는 '61,000평~66,000평'순으로 효용성을 보였다. 신국제여객터미널 실사업 주관자인 인천항만공사의 경우, 사용자 결과와 마찬가지로 중요도에서 '임대료 산정방식'이 신국제여객터미널 항만운영방안에서 가장 중요한 요인으로 나타났으며, 자동화구축, 부지면적 순으로 도출되었다. 각 요인의 수준별 효용결과로는 임대료산정방식에서는 '투자비 보전방식', 자동화구축에서는 '야드장치장의 자동화', 부지면적에서는 '43000평~48000평' 순으로 효용치를 보였다.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.804-811
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• 2015

The presence of responsive loads in the promising active distribution networks (ADNs) would definitely affect the power system problems such as distributed generations (DGs) studies. Hence, an optimal procedure is proposed herein which takes into account the simultaneous placement of DGs and smart meters (SMs) in ADNs. SMs are taken into consideration for the sake of successful implementing of demand response programs (DRPs) such as direct load control (DLC) with end-side consumers. Seeking to power loss minimization, the optimization procedure is tackled with genetic algorithm (GA) and tested thoroughly on 69-bus distribution test system. Different scenarios including variations in the number of DG units, adaptive power factor (APF) mode for DGs to support reactive power, and individual or simultaneous placing of DGs and SMs have been established and interrogated in depth. The obtained results certify the considerable effect of DRPs and APF mode in determining the optimal size and site of DGs to be connected in ADN resulting to the lowest value of power losses as well.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.196-203
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• 2022

The resource constrained scheduling problem (RCSP) constitutes one of the most challenging problems in Project Management, as it combines multiple parameters, contradicting objectives (project completion within certain deadlines, resource allocation within resource availability margins and with reduced fluctuations), strict constraints (precedence constraints between activities), while its complexity grows with the increase in the number of activities being executed. Due to the large solution space size, this work investigates the application of Genetic Algorithms to approximate the optimal resource alolocation and obtain optimal trade-offs between different project goals. This analysis uses the cost of exceeding the daily resource availability, the cost from the day-by-day resource movement in and out of the site and the cost for using resources day-by-day, to form the objective cost function. The model is applied in different case studies: 1 project consisting of 10 activities, 4 repetitive projects consisting of 40 activities in total and 16 repetitive projects consisting of 160 activities in total, in order to evaluate the effectiveness of the algorithm in different-size solution spaces and under alternative optimization criteria by examining the quality of the solution and the required computational time. The case studies 2 & 3 have been developed by building upon the recurrence of the unit/sub-project (10 activities), meaning that the initial problem is multiplied four and sixteen times respectively. The evaluation results indicate that the proposed model can efficiently provide reliable solutions with respect to the individual goals assigned in every case study regardless of the project scale.