• 제목/요약/키워드: 비용접근법

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연료 공급 및 저장 제약 하에서의 Long-Term Profit-Based Unit Commitment Problem 최적화를 위한 Explicit Column Generation 알고리즘

  • Lee, Gyeong-Sik;Song, Sang-Hwa
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2006.11a
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    • pp.75-89
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    • 2006
  • 한국전력산업의 탈규제화의 영향으로 각 개별 발전회사들은 자사의 이익을 최대화하기 위한발전계획 수립에 큰 관심을 가지게 되었다. 발전계획은 주어진 연료제약 하에 발전수익과 유지보수비용을 고려하여 시간대별 발전기의 기동, 정지 및 발전출력을 결정하는 문제로서Profit-Based Unit Commitment (PBUC) 문제로 알려져 있다. PBUC 문제는 문제 자체의 복잡성과 비선형 제약식의 특성으로 인하여 과거 연구는 대부분 비선형 제약식 처리를 위한 Lagrangian Relaxation (LR) 기반 휴리스틱 접근법에 초점이 맞추어져 왔다. 하지만, 실제현업 적용에 있어 계산시간이 많이 소요되고 알고리즘의 구현에 많은 기간이 소요되어 실용성은 낮은 것으로 보고되었다. 특히 연료도입 및 저장제약을 고려하기 위한 1년 단위 장기 발전계획 수립은 문제의 범위가 더욱 넓어짐으로 인하여 복잡성이 매우 크게 증가하고, 이에 따라 기존 접근법에 한계가 있어 왔다. 이에 본 연구에서는 국내가스발전소의 사례를 중심으로 발전패턴개념의 도입 및 다양한 발전패턴 생성을 통한 Explicit Column Generation 기반 최적화 접근법을 제안한다. 발전패턴은 Column Generation 접근법의 각 Column에 해당하는 각주별 발전기 기동정지계획을 의미한다. 즉, 미리 유효한 발전패턴의 Pool을 최대한 확보한 후 Explicit Column Generation Formulation을 통하여 주별 최적의 발전패턴을 찾아내는 알고리즘으로 구성이 된다. 본 알고리즘은 실제 가스발전소의 장기 발전계획 수립과정에 적용되어 효과적으로 운용되고 있으며 연간 수십억원의 추가적인 이익을 실현할 것으로 분석되었다. 본 알고리즘을 확장 적용할 경우 PBUC 문제 해결을 위한 새로운 해법으로도 그 효용성이 클 것으로 예상된다.자료이기 때문에 통계적 활용의 범위가 방대하다. 특히 개인, 가구, 사업체 등 사회 활동의 주체들이 어떻게 변화하는지를 추적할 수 있는 자료를 생산함으로써 다양한 인과적 통계분석을 할 수 있다. 행정자료를 활용한 인구센서스의 이러한 특징은 국가의 교육정책, 노동정책, 복지정책 등 다양한 정책을 정확한 자료를 근거로 수립할 수 있는 기반을 제공한다(Gaasemyr, 1999). 이와 더불어 행정자료 기반의 인구센서스는 비용이 적게 드는 장점이 있다. 예를 들어 덴마크나 핀란드에서는 조사로 자료를 생산하던 때의 1/20 정도 비용으로 행정자료로 인구센서스의 모든 자료를 생산하고 있다. 특히, 최근 모든 행정자료들이 정보통신기술에 의해 데이터베이스 형태로 바뀌고, 인터넷을 근간으로 한 컴퓨터네트워크가 발달함에 따라 각 부처별로 행정을 위해 축적한 자료를 정보통신기술로 연계${cdot}$통합하면 막대한 조사비용을 들이지 않더라도 인구센서스자료를 적은 비용으로 생산할 수 있는 근간이 마련되었다. 이렇듯 행정자료 기반의 인구센서스가 많은 장점을 가졌지만, 그렇다고 모든 국가가 당장 행정자료로 인구센서스를 대체할 수 있는 것은 아니다. 행정자료로 인구센서스통계를 생산하기 위해서는 각 행정부서별로 사용하는 행정자료들을 연계${cdot}$통합할 수 있도록 국가사회전반에 걸쳐 행정 체제가 갖추어져야 하기 때문이다. 특히 모든 국민 개개인에 관한 기본정보, 개인들이 거주하며 생활하는 단위인 개별 주거단위에 관한 정보가 행정부에 등록되어 있고, 잘 정비되어 있어야 하며, 정보의 형태 또한 서로 연계가 가능하도록 표준화되어있어야 한다. 이와 더불어, 현재 인구센서스에서 표본조사를 통해 부가적으로 생산하는 경제활동통계를 생산하기 위해서는 개인이 속한 사업체를 파악할 수 있도록 모든 사업체가 등록되어

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Reliability Evaluation Using a Parametric Approach (파라미터 접근법을 이용한 정전비용 변화에 따른 신뢰도지수 평가)

  • Moon, Guk-Hyun;Joo, Sung-Kwan;Park, Jong-Bae;Choi, Jae-Seok;Cha, Jun-Min;Ryoo, Sung-Ho;Kim, Hong-Hee
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.597_598
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    • 2009
  • 전력계통의 신뢰도 평가는 전기에너지 공급을 안정적으로 유지하기 위해 이루어진다. 최근 국내 전력산업에 경쟁적 시장 환경이 조성됨에 따라, 신뢰도 평가 연구에 시장 근원적인 특성을 반영하는 것은 중요한 문제로 부각되고 있다. 본 논문에서는 파라미터 접근법을 이용하여 정전비용 변화에 따른 신뢰도지수를 분석해 보았다. 수요 데이터의 시나리오 기법을 활용한 다년간의 사례연구를 수행하여 신뢰도 평가 모델의 효용성을 입증한다.

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Evaluating Reverse Logistics Networks with Centralized Centers : Hybrid Genetic Algorithm Approach (집중형센터를 가진 역물류네트워크 평가 : 혼합형 유전알고리즘 접근법)

  • Yun, YoungSu
    • Journal of Intelligence and Information Systems
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    • v.19 no.4
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    • pp.55-79
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    • 2013
  • In this paper, we propose a hybrid genetic algorithm (HGA) approach to effectively solve the reverse logistics network with centralized centers (RLNCC). For the proposed HGA approach, genetic algorithm (GA) is used as a main algorithm. For implementing GA, a new bit-string representation scheme using 0 and 1 values is suggested, which can easily make initial population of GA. As genetic operators, the elitist strategy in enlarged sampling space developed by Gen and Chang (1997), a new two-point crossover operator, and a new random mutation operator are used for selection, crossover and mutation, respectively. For hybrid concept of GA, an iterative hill climbing method (IHCM) developed by Michalewicz (1994) is inserted into HGA search loop. The IHCM is one of local search techniques and precisely explores the space converged by GA search. The RLNCC is composed of collection centers, remanufacturing centers, redistribution centers, and secondary markets in reverse logistics networks. Of the centers and secondary markets, only one collection center, remanufacturing center, redistribution center, and secondary market should be opened in reverse logistics networks. Some assumptions are considered for effectively implementing the RLNCC The RLNCC is represented by a mixed integer programming (MIP) model using indexes, parameters and decision variables. The objective function of the MIP model is to minimize the total cost which is consisted of transportation cost, fixed cost, and handling cost. The transportation cost is obtained by transporting the returned products between each centers and secondary markets. The fixed cost is calculated by opening or closing decision at each center and secondary markets. That is, if there are three collection centers (the opening costs of collection center 1 2, and 3 are 10.5, 12.1, 8.9, respectively), and the collection center 1 is opened and the remainders are all closed, then the fixed cost is 10.5. The handling cost means the cost of treating the products returned from customers at each center and secondary markets which are opened at each RLNCC stage. The RLNCC is solved by the proposed HGA approach. In numerical experiment, the proposed HGA and a conventional competing approach is compared with each other using various measures of performance. For the conventional competing approach, the GA approach by Yun (2013) is used. The GA approach has not any local search technique such as the IHCM proposed the HGA approach. As measures of performance, CPU time, optimal solution, and optimal setting are used. Two types of the RLNCC with different numbers of customers, collection centers, remanufacturing centers, redistribution centers and secondary markets are presented for comparing the performances of the HGA and GA approaches. The MIP models using the two types of the RLNCC are programmed by Visual Basic Version 6.0, and the computer implementing environment is the IBM compatible PC with 3.06Ghz CPU speed and 1GB RAM on Windows XP. The parameters used in the HGA and GA approaches are that the total number of generations is 10,000, population size 20, crossover rate 0.5, mutation rate 0.1, and the search range for the IHCM is 2.0. Total 20 iterations are made for eliminating the randomness of the searches of the HGA and GA approaches. With performance comparisons, network representations by opening/closing decision, and convergence processes using two types of the RLNCCs, the experimental result shows that the HGA has significantly better performance in terms of the optimal solution than the GA, though the GA is slightly quicker than the HGA in terms of the CPU time. Finally, it has been proved that the proposed HGA approach is more efficient than conventional GA approach in two types of the RLNCC since the former has a GA search process as well as a local search process for additional search scheme, while the latter has a GA search process alone. For a future study, much more large-sized RLNCCs will be tested for robustness of our approach.

Loosely Coupled Mixed Reality (약하게 결합된 혼합현실)

  • Lee, Myung-Ho;Lee, Myung-Hee;Kwon, Eun;Kim, Gerard J.
    • 한국HCI학회:학술대회논문집
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    • 2008.02a
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    • pp.72-77
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    • 2008
  • 본 논문은 혼합현실(Mixed reality) 에 대한 새로운 접근법을 제시한다. 혼합현실은 실제환경 (Real environment)과 가상환경 (Virtual environment) 이 융합된 가상현실로서 기존의 혼합현실 연구자들은 두 환경을 가능한 정확하게 정합(Registration)시키고자 노력하였다. 이러한 노력은 때때로 복잡한 계산과정이나 부가적인 장치를 요하기도 한다. 부가적인 장치의 사용은 사용성문제를 유발할 뿐만 아니라 추가적인 비용도 요구한다. 우리가 제시하는 접근법은 이러한 노력들과는 반대로 많은 부분을 사용자의 인지력과 상상력에 의지한다. 즉, 사용자의 인지력으로 두 환경 간의 오차를 보정하며 심지어는 사용자에 의해 두 환경 간의 결합이 머릿속에서 이루어진다. 우리는 이러한 접근 방법을 Loosely Coupled Mixed Reality(LMR)라고 부른다. 본 논문에서는 혼합현실에 대한 새로운 접근법인 LMR에 대해 설명하고 LMR이 갖는 여러 가지 쟁점을 짚어보았다. 또한 LMR의 효과를 검증하기 위해 만든 골프 게임을 설명 하도록 하겠다.

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Measuring Willingness to Pay for PM10 Risk Reductions: Evidence from Averting Expenditures for Anti-PM10 Masks and Air Purifiers (미세먼지 건강위험 감소에 대한 지불의사 측정: 마스크 착용과 공기청정기 사용에 따른 회피비용을 중심으로)

  • Eom, Young Sook;Kim, Jin Ok;Ahn, So Eun
    • Environmental and Resource Economics Review
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    • v.28 no.3
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    • pp.355-383
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    • 2019
  • This study is to investigate whether averting costs for wearing $anti-PM_{10}$ masks and using air purifiers at home to reduce exposure from $PM_{10}$ are influenced by subjective risk perceptions and/or objective $PM_{10}$ concentration levels, whose estimates will be used to measure the willingness to pay for $PM_{10}$ risk reduction. An empirical analysis was conducted on a sample of 1,224 respondents who participated in the web-based survey in the late October of 2017. As we reflect the potential endogeniety bias in the estimation of averting cost functions of using air purifiers, the coefficients of risk perception were differed by 6~7 times. Respondents. subjective risk perceptions were influenced by individuals' knowledge, attitudes and demographic variables, as well as the levels of $PM_{10}$ concentrations in their residential region. The marginal willingness to pay for risk reductions at the mean levels of their risk perceptions were measured at 1,000 won per month from wearing $anti-PM_{10}$ masks and 6,000 won for using air purifiers respectively.

A Test Case Prioritization Technique via Value-Based Approach (가치기반 접근법을 통한 테스트 케이스 우선순위 기법)

  • Park, Hyun-Cheol;Ryu, He-Yeon;Baik, Jong-Moon
    • Journal of KIISE:Software and Applications
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    • v.36 no.5
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    • pp.353-360
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    • 2009
  • Software, once developed, has a long life and evolves through numerous additions and modifications because of the faults, the changes in user requirements, the changes in environments, and so forth. With the evolution of the software, assuring the quality of the software is getting more difficult because of numerous versions of the software. Meanwhile, regression testing has been used to support the software testing activities and assure acquiring appropriate quality through several versions of software. Regression testing, however, is too expensive because it requires lots of test cases executions and the number of test cases increases sharply as the software evolves. For this reason, several techniques are suggested to help conducting regression testing then test case prioritization technique is understood the most effective and efficient technique to support regression testing. In this paper, we propose an approach, Historical Value-Based Approach, which is based on the use of historical information to estimate the current cost and fault severity for cost-cognizant test case prioritization. As a result of the proposed approach, software testers who perform regression testing prioritize their test cases more effectively so that the test effectiveness of them can be improved in terms of APFDc.

A Software Design Methodology Integrating Evaluation Method of Architectural Design Approaches (아키텍처기반 설계 방식에 대한 평가기능이 통합된 소프트웨어 설계 방법론)

  • Koh, Hyon-Hee;Kung, Sang-Hwan;Park, Jae-Nyon
    • Journal of KIISE:Software and Applications
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    • v.34 no.7
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    • pp.625-634
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    • 2007
  • Due to the software is getting complex and large, software architecture design is issued for success of project. In the design phase, selection of the suitable architectural approach is very important. In this thesis, we identify the architectural approach alternatives in the design phase. And the evaluation method to choose architectural approaches and the architecture design methodology integrated with that evaluation method are proposed In the proposed architecture evaluation method and the architecture design methodolody, we intend to raise reliability, completeness of design and reduce development costs.

Core Exchanger 주변 열교환기들의 효율적인 에너지 관리를 위한 열 교환망 합성에 관한 연구

  • 조석연;서경원
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 1996.04a
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    • pp.136-143
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    • 1996
  • 본 연구에서는 정유공정의 한 부부인 demethanizer의 core exchanger 주위 열교환기들에 대해 핀치설계법(pinch desgin method)을 이용하여 새로운 열교환망 합성을 수행하였다. 이로부터 초기에 설정했던 최소접근온도차가 총비용, 즉, 장치비와 에너지 비용에 결정적인 역할을 하는 것으로 확인되었다. 따라서, 본 연구에서는 이 총비용의 목표값이 최소가 되는 최적 최소접근온도차가 존재하고, 이로부터 열교환망 합성이 수행되어져야 최적의 열교환망 합성이 이루어져야 한다는 결론을 얻었다.

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A Study on the Technology Evaluation of Development of New Variety of Citrus Unshiu (감귤 신품종(하양조생)개발의 기술가치의 평가)

  • Ko, Seong-Bo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.8
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    • pp.127-132
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    • 2016
  • This study evaluated the economic value of the development of a new variety of Citrus unshiu using the income approach, Net Present Value (NPV), Internal Rate of Return (IRR), and Benefit/Cost (B/C) ratio. The new variety of Citrus unshiu was developed by the national institute of horticultural and herbal science in Korea, rural development administration. The technological evaluation of the development of a new variety of Citrus unshiu can be used to improve the efficiency and practicality of the development of a new variety of citrus. From the research results, the technological value of development of a new variety of Citrus unshui was evaluated at 109,455(discount rate=8%, minimum), 195,040(discount rate=4%, maximum), and 145,375(discount rate=6%, average) million won. The IRR was 51.4%, which was greater than the discount rate(4~8%). The NPV was evaluated at 145.3 billion won(discount rate=6%, average), 195.0 billion won(discount rate=4%, maximum) and 109.4 billion won(discount rate=8%, minimum), all of which were greater than 0. The B/C ratio was evaluated at 60.9(discount rate=6%, average), 81.3(discount rate=4%, maximum) and 46.1(discount rate=8%, minimum), all of which were greater than 1. Therefore, the economic validity of the development of a new variety of Citrus unshiu was identified by this technological evaluation.

A Study of Cold Chain Logistics in China: Hybrid Genetic Algorithm Approach (중국 콜드체인 물류에 관한 연구: 혼합유전알고리즘 접근법)

  • Chen, Xing;Jang, Eun-Mi
    • Journal of Korea Society of Industrial Information Systems
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    • v.25 no.6
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    • pp.159-169
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    • 2020
  • A cold chain logistics (CCL) model for chilled food (-1℃ to 8℃) distributed in China was developed in this study. The CCL model consists of a distribution center (DC) and distribution target points (DT). The objective function of the CCL model is to minimize the total distribution routes of all distributors. To find the optimal result of the objective function, the hybrid genetic algorithm (HGA) approach is proposed. The HGA approach was constructed by combining the improved K-means and genetic algorithm (GA) approaches. In the case study, three scenarios were considered for the CCL model based on the distribution routes and the available distance, and they were solved using the proposed HGA approach. Analysis results showed that the distribution costs and mileage were reduced by approximately 19%, 20% and 16% when the proposed HGA approach was used.