• Journal of the Korea Society for Simulation
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• v.7 no.1
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• pp.53-68
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• 1998

FCM은 비구조적인 (unstructured) 문제영역에서 주어진 문제에 대한 효과적인 추론시 적용될 수 있는 매우 유용한 추론도구이다. 그러나, FCM에 사이클이 존재하면 추론효과가 크게 감소한다. 본 노문에서는 사이클이 있는 FCM을 이용한 의사결정의 질을 높일 수 있는 추론방법을 제시한다. 아울러 사이클이 제거된 FCM의 추론이 질을 저하시키는 문제중의 하나인 동기화 문제 (synchronization problem)를 설명하고, 이를 해결하기 위한 방안으로서 FCM 계층화 (levelization) 알고리즘을 제시한다.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.562-564
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• 1995

This paper proposes a new algorithm for maintenance scheduling with considering load forecast uncertainty. The proposed algorithm is based on the equivalent load of effective load carrying capability(ELCC) of generators. The uncertainty of forecasted load is considered as a normal distribution probability density function. For maintenance scheduling, reserve levelization method and risk levelization method are used in this study. To test the algorithm, we applied the proposed method to IEEE reliability test system(IEEE RTS). As a result, we verified the validity of the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.11
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• pp.1374-1381
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• 1999

This paper describes development of a package for generator maintenance scheduling program with user-friendly interactive mode. Generator maintenance scheduling is to select desirable maintenance periods of generators in the given interval satisfying reliability or economic criteria. Window-based system for user-friendly mode and Oracle-based database system for efficient data management are established in our package. Reserve rate levelization and LOLP minimization are performed in calculation mode, which is composed of DLL programs. Many graphs and charts are illustrated for the user-analysis. Operation is carried out by day-based unit, not by week. The case study has been conducted with the data of practical KEPCO power system in 1999 and successfully demonstrated its effectiveness.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.4
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• pp.203-212
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• 1998

본 논문에서는 FCM을 이용하여 의사결정의 질을 높일 수 있는 추론방법을 제시한다. 이를 위하여 FCM의 추론의 질을 저하시키는 문제중의 하나인 동기화 문제(synchronizatinon Problem)를 설명하고. 이를 해결하기 위한 방안으로서 FCM 계층화(levelization) 알고리즘을 제시한다. 본 논문에서 제안된 계층화된 FCM을 이용한 추론절차를 제시하고, 그 활용예를 설명한다.

• Proceedings of the Korea Society for Simulation Conference
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• 1998.10a
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• pp.57-61
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• 1998

FCM은 비구조적인 (unstructured) 문제영역에서 주어진 문제에 대한 효과적인 추론시 적용될 수 있는 매우 유용한 추론도구이다. 그러나, FCM에 사이클이 존재하면 추론효과가 크게 감소한다. 본 논문에서는 사이클이 있는 FCM을 이용하여 의사결정의 질을 높일 수 있는 추론방법을 제시한다. 이를 위하여 FCM내에 존재하는 사이클을 확인하고 해소하는 알고리즘을 제시한다. 아울러 사이클이 제거된 FCM의 추론의 질을 저하시키는 문제중의 하나인 동기화 문제 (levelization) 알고리즘을 제시한다.

• Journal of Energy Engineering
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• v.27 no.4
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• pp.50-63
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• 2018

The issue of global warming and environmental pollutant has become an international concern due to the widespread use of fossil fuels, and thus waste heat recovery technologies has become important to improve energy utilization. The global market of power generation system using industrial waste heat is rapidly growing at an average rate of 5% due to its advantage of increasing energy efficiency. In order to design an optimal waste heat recovery system, it is necessary to develop a program that offers economic evaluation of each power generating technology according to the heat source conditions. In this paper, the economic analysis module to calculate LCOE is developed and verified the reliability against NETL economic analysis results. As a result of the verification, the error rate is about 6 ~ 7%, which satisfy the accuracy for business feasibility evaluation. In order to enhance the reliability, the module was improved by applying the levelization method used by NETL. As a result of the verification of reliability, the error rate is less than 1% and the accuracy is improved.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.216-217
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• 2006

This paper presents development of program for generator maintenance scheduling. The maintenance scheduling of generating units is a dynamic discrete combinatorial optimization problem with constraints to determine the optimal maintenance periods of each generating units for a given planning periods. The developed program is designed so as to provide the maintenance schedule satisfying the operating reserve margin levelization and the procurement of proper reliability. In order to verify the effectiveness of the developed program, the numerical study has been performed with the practical data in 2005.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.1
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• pp.61-71
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• 2014

Social networking services have changed the way people communicate. Rapid growth of information generated by social networking services requires effective search methods to give useful results. Over the last decade, social search methods have rapidly evolved. Traditional techniques become unqualified because they ignore social relation data. Existing social recommendation approaches consider social network structure, but social context has not been fully considered. Especially, the friend recommendation is an important feature of SNSs. People tend to trust the opinions of friends they know rather than the opinions of strangers. In this paper, we propose a levelized data processing method for social search in ubiquitous environment. We study previous researches about social search methods in ubiquitous environment. Our method is a new paradigm of levelelized data processing method which can utilize information in social networks, using location and friendship weight. Several experiments are performed and the results verify that the proposed method's performance is better than other existing method.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.11
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• pp.132-139
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• 1993

This paper presents a new performance-driven multi-levelizer which transforms a two-level description into a boolean network of the multilevel structure satisfied with user's costraints, such as chip area, the number of wires and literals, maximum delay, function level, fanin, fanout, etc.. The performance of circuits is estimated by reference to the informations in cell library through the cell mapping phase, and multi-levelization of circuits is constructed by the decomposition using the kernel and factoring concepts. Here, the saving cost of a common subexpression is defined to the sum of area and delay saved, when it is substituted. The experiments with MCNC benchmarks show the efficiency of the proposed method.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.89-95
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• 1998

Maintenance scheduling of generators plays an important role in evaluating supply reliability of power systems. Since generators must be maintained and inspected, the generation planner must schedule planned outages during the year. Several factors entering into this scheduling analysis include: seasonal load-demand profile, amount of maintenance, size of the units, elapsed time from last maintenance, and availability of maintenance crew. This paper proposes a new maintenance scheduling algorithm for the alternatives of long-term generation expansion planning by using LOLP levelization method which is known as an effective method for the generator's maintenance scheduling. To get the best supply reliability of power systems, we change the maintenance period to levelize the reliability over all period. The proposed algorithm is applied to a real size power system and the better reliability results are obtained.