• 전기학회논문지
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• 제65권4호
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• pp.555-560
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• 2016

Recently, many countries have placed great attention on energy security and climate changes. Governments are promoting the construction of renewable energy projects with regulatory support in Korea. Despite an increasing penetration of renewable resources, however, the photovoltaic and wind power are underutilized due to the endemic problems such as difficulties of output control and intermittent output. The Energy Storage System (ESS) is proposed as a good solution for solving the problems and has been studied in both the private business and the government. However, because of inefficient aspects, the research has been carried out for improving high costs and a small capacity. In addition, the ESS is currently installed for using only one purpose which is frequency regulation or transmission congestion relief such that has an economic limitation. Therefore, methods which are becoming economically justifiable to increase the penetration of the ESS is required. Thus, this paper presents in terms of operation efficiency to improve economic feasibility of the ESS currently used. mainly, there are two aspects for the operation efficiency. Firstly, it is intended to improve the utilization rate through a process that can utilize the ESS for various purposes. It is necessary to be able to use for other purposes by classifying and clustering for increasing the efficiency of availability. The clustering method is proposed to conduct the grouping the ESS. Especially, it is proposed to utilize ESS for frequency regulation service which is the one of ancillary services in the power system. Through case studies, it is confirmed to secure the necessary resources by clustering small size ESS.

• 농업과학연구
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• 제47권4호
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• pp.951-962
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• 2020

One hundred ninety-five countries reached agreement on a new climate treaty in Paris, France to reduce the carbon emissions. South Korea has been selected as a target country for reducing greenhouse gas (GHG) obligations since 2020. In this context, the Korean government developed several GHG emissions reduction programs using forests called the "Forest carbon offset scheme (FCOS)." The forest management method is one of the tools to implement FCOS. Most of the participants registered forest management as the preferred methodology to participate in the FCOS. For a successful implementation of the FCOS, it is necessary to explore the optimal methods by considering the cost-effective aspect of conducting the forest management as a tool to increase carbon absorption. In this context, this study investigated the value optimized FCOS projects based on the forest management methodology in South Korea. Three forest management scenarios, 1) extending the final age of maturity of Pinus densiflora stands (S1), 2) extending the final age of maturity of Quercus acutissima stands (S2), and 3) reforestation with new species (Pinus densiflora to Quercus acutissima) (S3), were examined and evaluated to identify the optimal carbon absorption and value optimized economic perspective. The results of the scenario-based modelling indicated that S3 showed value optimized from an economical perspective, and S2 was the most effective method to absorb carbon among the scenarios. It is anticipated that this paper will contribute to provide valuable information by presenting innovative approaches as a value optimized FCOS implementing tool in a GHG reduction program in South Korea.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.321-322
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• 2008

주파수는 발전기 조속기와 전적거래소 EMS AGC의 협조제어 체계가 적절하여야 안정적인 운영이 가능하며, 과다한 주파수 조정은 경제급전을 저해함은 물론 발전기의 수명단축을 초래하기 때문에 AGC 최적튜닝은 필수적이다. 본 논문에서는 '07년도에 거래소 계통운영처에서 수행한 AGC 제어파라미터 튜닝기법 및 효과에 대해 논하고 있으며, 학계는 물론 동종업계에 AGC 관련 기술개발시 업무추진에 도움이 되었으면 한다.

• 마이크로전자및패키징학회지
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• 제22권2호
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• pp.1-4
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• 2015

Qualification includes all activities to demonstrate that a product meets and exceeds the reliability goals. Manufacturers need to spend time and resources for the qualification processes under the pressure of reducing time to market, as well as offering a competitive price. Failure to qualify a product could result in economic loss such as warranty and recall claims and the manufacturer could lose the reputation in the market. In order to provide valid and reliable qualification results, manufacturers are required to make extra effort based on the operational and environmental characteristics of the product. This paper discusses optimal interval censoring design for reliability prediction of electronic packages under limited time and resources. This design should provide more accurate assessment of package capability and thus deliver better reliability prediction.

• 설비공학논문집
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• 제21권8호
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• pp.439-447
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• 2009

Cogeneration system produces power as well as heat recovered from waste heat during power generation process. This system has higher energy efficiency than that of the power plant. In this study the optimal design for the cogeneration system with the increase of the capacity considering life cycle cost(LCC) analysis has been performed in the general facilities such as hotels and hospitals under the assumption of electricity cost of 95 won/kWh, the initial cost of cogeneration system of 1,500,000 won!kW and the value of 0.5${\sim}$1.0 in the ratio of heat to power. The optimal ratio of cogeneration capacity divided by average electricity load of facility was found out more than 0.5 in case of electricity cost with the increase of>30%, and the percentage of $CO_2$ reduction was about 9%. The most important factors in the economic analysis of cogeneration system was found out the electrity cost and the initial cost of cogeneration system. Also the ratio of heat to power at the value of>0.5 was not affected in the economy of cogeneration system, but was very important in the $CO_2$ reduction.

• Industrial Engineering and Management Systems
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• 제13권1호
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• pp.52-66
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• 2014

Promotion of a closed-loop supply chain requires disassembly systems that recycle end-of-life (EOL) assembled products. To operate the recycling disassembly system, parts selection is environmentally and economically carried out with non-destructive or destructive disassembly, and the recycling rate of the whole EOL product is determined. As the number of disassembled parts increases, the recycling rate basically increases. However, the labor cost also increases and brings lower profit, which is the difference between the recovered material prices and the disassembly costs. On the other hand, since the precedence relationships among disassembly tasks of the product also change with the parts selections, it is also required to optimize allocation of the tasks in designing a disassembly line. In addition, because information is required for such a design, the recycling rate, profit of each part and disassembly task times take precedence among the disassembly tasks. However, it is difficult to obtain that information in advance before collecting the actual EOL product. This study proposes and analyzes an optimal disassembly system design using integer programming with the environmental and economic parts selection (Igarashi et al., 2013), which harmonizes the recycling rate and profit using recyclability evaluation method (REM) developed by Hitachi, Ltd. The first stage involves optimization of environmental and economic parts selection with integer programming with ${\varepsilon}$ constraint, and the second stage involves optimization of the line balancing with integer programming in terms of minimizing the number of stations. The first and second stages are generally and mathematically formulized, and the relationships between them are analyzed in the cases of cell phones, computers and cleaners.

• Nuclear Engineering and Technology
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• 제21권3호
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• pp.171-185
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• 1989

유연탄 발전과 원자력 발전의 경제성 평가를 균등한 인체 위험도 하에서 서기 2000년의 시점에서 수행하였다. 유연탄 발전과 원자력 발전의 인체에 대한 영향 비교에서, 유연탄의 영향이 원자력에 비해서 10배가량 높은 것을 에너지 시스템의 위험도 평가에 관한 여러 연구결과들로부터 알 수 있었다. 그런데 위험도가 0인 상태는 존재하지 않으므로, 유연탄 발전과 원자력 발전간의 위험도 차이만을 본 논문의 위험도로 간주했다. 인체 위험도 비용은 사망과 질병의 두 경우로 나누어서, 사망의 경우에는 Human Life Value로 계산하고, 질병의 경우에는 완치될 때까지의 치료비등 제반 비용으로 계산했다. 이러한 방법에 의한 계산 결과 사망의 비용은 ＄250,000이 되었고, 질병의 경우는 ＄90,000이 되었다. (1986 US＄) 그리고 비용편익분석을 통해서 유연탄 화력 발전의 최적 규제 기준치를 구했는데, 이 규제치는 최소 사회비용이 발생되는 지점에서 구해졌다. 서기 2000년의 한국에서의 SOx에 대한 최적 규제치는 165ppm으로 나타났다. 이러한 전력 생산의 경제성 평가 방법으로부터, 원자력이 유연탄 화력에 비해서 더 경제적인 것으로 나타났다. 반면에 불확실도는 유연탄화력이 더 작은 것으로 나타났다.

• 한국지진공학회논문집
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• 제10권6호
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• pp.47-56
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• 2006

지진응답 제어를 위하여 사장교 구조물에 장착된 준능동MR 댐퍼의 경제적 효율성 평가기법을 제안하였으며, 다양한 지반운동 특성에 대하여 비용효율성을 극대화하는 MR 댐퍼의 최적용량에 대한 분석을 수행하였다. MR 댐퍼의 비용효율성 평가를 위하여 생애주기비용 개념을 적용하였으며, 생애주기비용을 이루는 비용항목 중 손상비용의 기대값을 평가하기 위하여 지진재해로 인한 사장교의 파괴확률을 추정하였다. 사장교의 파괴로 인한 직 간접 손상비용의 규모를 매개변수로 하여 비용효율성을 평가하였다. 비용효율성 평가지수는 MR 댐퍼의 장착으로 인한 추가 투자비용과 사장교 구조물의 손상비용으로 이루어진 함수로서, 탄성받침이 사용된 기존의 설계에 대한 경제적 효율성을 나타내도록 정의하였다. 사장교의 지진응답 제어를 위하여 장착된 MR 댐퍼는 경제적으로 효율적인 대안인 것으로 나타났다. 지반운동의 특성과 손상비용 규모에 대한 MR 댐퍼의 최적 용량을 분석한 결과, 지진위험도 및 손상비용 규모가 커짐에 따라 가장 높은 비용효율성을 가지는 MR 댐퍼용량이 증가하는 것을 확인할 수 있었다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2003년도 춘계공동학술대회
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• pp.660-667
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• 2003

In this study, a Multiple Objective Mixed Integer Programming (MOMIP) Model is developed for sewer rehabilitation planning by considering cost, inflow/infiltration. A sewer rehabilitation planning model is required to decide the economic life of the sewer by considering trade-off between cost and inflow/infiltration. And it is required to find the optimal rehabilitation timing, according to the cost effectiveness of each sewer rehabilitation within the budget. To develop such a model, a multiple objective mixed integer programming model is formulated based on network flow optimization. The network is composed of state nodes and arcs. The state nodes represent the remaining life and the arcs represent the change of the state. The model consider multiple objectives which are cost minimization and minimization of inflow/infiltration. Using the multiple objective optimization, the trade-off between the cost and inflow/infiltration is presented to the planner so that a proper sewer rehabilitation plan can be selected.

• 산업경영시스템학회지
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• 제29권3호
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• pp.135-142
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• 2006

Engineers are always concerned with life cycle costs for making important economic decisions through engineering action like reliability of products. Decisions during the reliability growth development of products involve trade-offs between invested costs and its returns. In order to find minimal LCC containing the reliability improvement cost, production cost, repair and replacement costs, and holding cost of spare parts for failure items we suggest in this paper relationship between development cost and sustaining cost in values of growth parameter $\beta$ of AMSAA model. This model is applied to the reliability growth program based on AMSAA model during R&D phase, the warranty activities of items and the block replacement policy for maintenance of items in avionic equipment.