• 한국경영과학회지
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• 제33권1호
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• pp.117-129
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• 2008

Make-to-order manufacturers with multiple plants at multiple sites need to have the ability to quickly determine which plant will produce which customer order to meet the due date and minimize the transportation cost from the plants to the customer. Balancing the work loads and minimizing setups and make-span are also of great concern. Solving such scheduling problems usually takes a long time. We propose a new approach, which we call 'preprocessing', for resolving such complex problems. In preprocessing scheme, a 'good' a priori schedule is prepared and maintained using unconfirmed order information. Upon the confirmation of orders. the preprocessed schedule is quickly modified to obtain the final schedule. We present a preprocessing solution algorithm for multi-site constraint scheduling problem (MSCSP) using genetic algorithm; and conduct computational experiments to evaluate the performance of the algorithm.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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• pp.204-208
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• 1996

일반적으로 한 제품은 원자재로부터 중간의 여러 단계의 공장을 거쳐 최종 완제품으로 시장에 선보이게 된다. 이러한 다공장 구조에서는 제조기업 전체차원, 하부 공장차원, 단위작업장 차원을 유기적으로 연결하여 생산계획 및 생산통제를 담당하는 운영시스템이 필요하다. 본 연구에서는 Jacobson[2]의 Use Case Driven기법을 이용하여 이러한 다공장의 계층적 구조를 가진 생산계획및 통제시스템에 대한 객체지향적 분석 및 설계을 수행하였다. 우선 각 계층의 시스템에 대하여 Actor와 Use case를 도출하였다. 그리고 도출된 Use-case로 부터 객체를 규명하여 시스템에 대한 분석모델을 수립하였다. 또한 주요 Use-case를 규명된 객체간의 메시지 교환과 통제의 이행과정을 통하여 표현함으로써 시스템의 객체지향적 구현의 기반을 구축하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1663-1664
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• 2008

Many years ago, most of thermal power plants built in this country were of subcritical pressure, of medium or small size, of constant pressure operations and of drum type steam generators with circulation type boilers. But, nowadays almost all of them were of high efficiency, of supercritical pressure, of big capacity, of sliding pressure operations, and of once through type steam generators. Presently built once through boilers introduce turbine bypass systems to variable pressure operation which eliminates unexpected materials in boiler tube during startup, minimizes fuel loss by short startup period and eventually improve both total efficiency and power system stability.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
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• pp.734-741
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• 2002

The importance of efficient Supply Chain Management is increasing in accordance with recent industrial environment, such as globalization of business, complexity and diversity of company's management structure, and variety of customer's demand. In a rapidly changed environment of business, quick and efficient decision making is the important matter to the survival of the company. The purpose of this study supports decision making for efficient supply chain management. In this study, we consider simultaneously and mutually reflecting the preference of each constituent (Supplier, Manufacturing plant, Distribution center, Customer) on supply chain network, and decide company's strategic choice and coordinated production/distribution models of company. The Analytical Hierarchy Process is used for decision making of qualitative and quantitative elements. We use the results of AHP as inputs and propose mathematical models thru Mixed Integer Programming.

• Nuclear Engineering and Technology
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• 제37권1호
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• pp.109-117
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• 2005

Limiting conditions for operations (LCOs) are evaluated dynamically using the tool of system dynamics. The LCOs de-fine the allowed outage times (AOTs) and the actions to be taken if the repair cannot be completed within the AOT. System dynamics has been developed to analyze the dynamic reliability of a complicated system. System dynamics using Vensim software have been applied to LCOs assessment for an example system, the auxiliary feed water system of a reference nuclear power plant. Analysis results of both full power operation and shutdown operation have been compared for a measure of core damage frequency. The framework developed in this study has been shown to be very flexible in that it can be applied to assess LCOs quantitatively under any operational context of the TS in FSAR.

• KSBB Journal
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• 제15권4호
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• pp.342-345
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• 2000

식물세포배양으로부터 peroxidase를 대량 생산하기 위한 분리/정제 공정 으로서 세포를 파쇄하고 크로마토그래피 전처리로서 활성백토를 적용하였다. 활성백토는 미세한 세 포 조각 뿐만 아니라 여려가지 불순불을 선택적으로 흡착 하는 성질을 나타내었으며, 이를 통하여 효과적으로 정제 공정을 진행할 수 있었다 흡착을 통한 전처리 후 한외여 과장치를 이용하여 농축을 실시 하였으며, DEAE-Sepharose F FF를 이용한 크로마토그래피를 통해 정제가 이루어졌다. 활성을 나타내는 용액을 탈염, 농축 후 동결 건조하였다. 이 공정은 상업화에 필요한 대량 정제를 가능하게 하였으며 수율과 정제비용 측면에서 상당히 경제적인 공정임을 입증하였다, 활성백토를 이용한 흡착공정은 다른 효소 및 단백질의 경제적인 대량정제에 적용될 수 있으리라 기대된다.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2127-2137
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• 2017

A virtual power plant (VPP) is a system that virtually integrates power resources based on the VPP participating customer (VPC) unit and operates as a power plant. When VPP operators manage resources to maximize their benefits, load reduction instructions may focus on more responsive VPCs, or those producing high profitability, by using VPC resources with high operation efficiency. VPCs may thus encounter imbalance problems during operation. This imbalance in operation time would bring more participation for some VPCs, causing potential degradation of their resources. Such an operation strategy would be not preferable for VPP operators in managing the relationship with VPCs. This issue impedes both continual VPC participation and economical and reliable VPP operation in the long term. An operation algorithm is therefore proposed that considers the operation time of VPC generators for mandatory reduction of power resource consumption. The algorithm is based on constraints of daily and annual operation times when VPP operators of local generators perform capacity-market power transactions. The algorithm maximizes the operator benefit through VPP operations. The algorithm implements a penalty parameter for imbalances in operation times spent by VPC generators in fulfilling their obligations. An evaluation was conducted on VPP operational effects by applying the algorithm to the Korean power market.

• 대한안전경영과학회지
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• 제17권1호
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• pp.271-279
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• 2015

Global warming has pressured companies to put a greater emphasis on environment management which allows them to reduce environmental impact and costs of their operations. In Korea, the coal-fired power plants take a large account of electricity generation at 31.7% of the total electricity usage in 2014. Thus, environmental impact of coal-fired power plants is significant. This paper illustrated how to compute environmental impact and costs in electricity generation at a coal-fired power plant using MFCA methodology. Compared to the traditional accounting, an advantage of MFCA is to provide information on electricity generation costs and environmental wastes incurring throughout the production process of electricity. Based on MFCA, the coal-fired power plant was able to reduce production cost of electricity by 52.3%, and environmental wastes by 47.7%. As a result, MFCA seemed to be an effective tool in environmental management for power plants.

• 한국지능시스템학회논문지
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• 제7권2호
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• pp.43-50
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• 1997

쓰러기 소각로는 다음과 같은 불명확한 요소들을 포함한다. 즉 연료로 사용되는 쓰레기의 물리적 특성의변동 그리고 연소현상의 복잡성 등이다. 이것은 기존의 제어기법을 쓰레기의 연소제어에 적용하기가 매우 어렵게 만든다. 따라서 대부분의 쓰레기 소각로는 조작자의 운전에 의존한다. 본 논문에서는 쓰레기 소각로의 연소제어를 위한 다변수퍼지모델 예측제어를 제안한다. 쓰레기 소각로의 모델을 구하기 위해 적응 네트워크에 기초한 퍼자추론시스템이 사용되고 동정된 퍼지 모델을 이용하여 다변수 퍼지모델 예측제어기가 설계된다. 그리고 제안된 제어기의 성능을 평가하기 위해 컴퓨터 시뮬레이션이 수행되었다.

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2577-2583
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• 2009

Presented are the formation of iron oxide layers on evaporator tubes in an actual fossil power plant operated under all volatile treatment (AVT) condition and an experimental simulation of iron oxide formation in the presence of ferrous and ferric ions. After actual operations for 12781 and 36326 hr in the power plant, two iron oxide layers of magnetite on the evaporator tubes were found: a continuous inner layer and a porous outer layer. The experimental simulation (i.e., artificial corrosion in the presence of ferrous and ferric ions at 100 ppm level for 100 hr) reveals that ferrous ions turn the continuous inner oxide layer on tube metal to cracks and pores, while ferric ions facilitate the production of porous outer oxide layer consisting of large crystallites. Based on a comparison of the oxide layers produced in the experimental simulation with those observed on the actually used tubes, we propose possible routes for oxid layer formation schematically. In addition, the limits of the proposed corrosion routes are discussed in detail.