• 대한수학회지
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• 제34권2호
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• pp.395-405
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• 1997

A globality of the Hopf bifurcation in a free boundary problem for a parabolic partial differential equation is investigated in this paper. We shall examine the global behavior of the Hopf critical eigenvalues and and apply the center-index theory to show the globality.

• 전자공학회논문지
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• 제50권4호
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• pp.246-251
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• 2013

본 논문에서는 분산 모바일 멀티미디어 통신망에서 유한한 대역폭을 공정하고 효율적으로 사용하기 위해 파산이론을 적용한 파산 대역폭할당 기법을 제안하였다. 제안된 파산 대역폭할당 기법은 협력게임이론에서 파산이론을 활용하여 파산상황에서 각 서비스의 최소 대역폭보장을 통해 각 서비스의 최소 QoS를 제공한다. 성능평가 결과로 제안한 파산 대역폭 할당기법(BBA)은 CEA, CEL, Reverse Talmud에 비해 공정성지수(FI:Fairness Index)를 통해 공정성 있고, Erlang blocking formular를 통해 서비스 차단율에 대해서도 높은 성능을 보임을 나타냈다. 제안된 파산 대역폭할당 기법은 분산 모바일 멀티미디어 통신망에서, 다양한 상황에서 서비스별 우선순위를 통한 대역폭 할당기법이나 동적인 대역폭 할당기법에 최소 대역폭 할당기준으로도 적용할 수 있다.

• Structural Engineering and Mechanics
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• 제63권5호
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• pp.639-646
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• 2017

According to the multi-index system of dam safety assessment and the standard of safety, a comprehensive evaluation model for dam safety based on a cloud model is established to determine the basic probability assignment of the Dempster-Shafer theory. The Dempster-Shafer theory is improved to solve the high conflict problems via fusion calculation. Compared with the traditional Dempster-Shafer theory, the application is more extensive and the result is more reasonable. The uncertainty model of dam safety multi-index comprehensive evaluation is applied according to the two theories above. The rationality and feasibility of the model are verified through application to the safety evaluation of a practical arch dam.

• 대한전기학회논문지:전력기술부문A
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• 제53권9호
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• pp.487-493
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• 2004

The electric power industry throughout the world is undergoing considerable changes from the vertically integrated utility structure to the deregulated market. However, the deregulated electricity market is operated with respect to theory of economical efficiency, and therefore, the system operator requires data with fast contingency ranking for security of the bulk power system. This paper compares the weather dependant probabilistic risk index(PRI) with the system performance index for power flow in the IEEE-RTS. The system performance index for power flow presents the power system stability. This paper presents fast calculation method for determining contingency ranking using the weather dependant probabilistic risk index(PRI). The probabilistic risk index can be classified into the case of normal and adverse weather. This paper proposes calculation method using the probabilistic risk index in determining contingency ranking required for security under the deregulated electricity market.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2009년도 춘계학술대회
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• pp.337-350
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• 2009

Using the Malmquist productivity index, this paper compares the productivity of Korean manufacturing industries from 1999 to 2006. The malmquist productivity index has more advantages than previous methods such as solow model, endogenous growth theory. The malmquist productivity index can be decomposed productivity into two parts. The first part is an index of the technical efficiency change. This index has high value when the elements of production is used more efficiently. The second part is an index of technical change. This index has high value if the advent of new technology and process innovation occur.

• 대한전자공학회논문지
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• 제23권4호
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• pp.522-528
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• 1986

Based on the modified effective index method, analysis of dielectric rectangular waveguides and directional couplers are presented. Aside from the effective index concept of channel region, the equivalent index concept of cladding region is proposed. The error problem of eigenvalues, which has been experienced when the effective index method is used, is improved. Our approxiamtions give similar accuracy when compared with the results of other regorous approxiamtion techiniques. The advantage of the modified effective index methods is utilized by replacing the directional coupler with the equivalent slab guides, and the coupling constant is calculated by the coupled mode theory. The effectiveness of the equivalent index concept is positively confirmed.

• 대한본초학회지
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• 제37권2호
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• pp.13-21
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• 2022

Objectives : The evaluation of academic achievement is pivotal for establishing accurate direction and adequate level of medical education. The purpose of this study was to firstly establish innovative item analysis technique of Item Response Theory (IRT) for analyzing multiple-choice test of herbology in the traditional Korean medicine education which has not been available for the difficulty of test theory and statistical calculation. Methods : The answers of 390 students (2012-2018) to the 14 item herbology test in college of Korean medicine were used for the item analysis. As for the multidimensional analysis of item characteristics, difficulty, discrimination, and guessing parameters along with item-total correlation and percentage of correct answer were calculated using Classical Test Theory (CTT) and IRT. Results : The validity parameters of strong and weak items were illustrated in multiple perspectives. There were 4 items with six acceptable index scores, and 5 items with only one acceptable index score. The item discrimination of IRT was found to have no significant correlation with difficulty and discrimination indices of CTT emphasizing attention of professionals of medical education as for the test credibility. Conclusion : The critical suggestions for the development, utilization and revision of test items in the e-learning and evidence-based Teaching era were made based on the results of item analysis using IRT. The current study would firstly provide foundation for upgrading the quality of Korean medicine education using test theory.

• 한국문헌정보학회지
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• 제6권
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• pp.87-103
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• 1979

Information storage and retrieval is a part of general communication process. In the Shannon's information theory, information contained in a message is a measure of -uncertainty about information source and the amount of information is measured by entropy. Indexing is a process of reducing entropy of information source since document collection is divided into many smaller groups according to the subjects documents deal with. Significant concepts contained in every document are mapped into the set of all sets of index terms. Thus index itself is formed by paired sets of index terms and documents. Without indexing the entropy of document collection consisting of N documents is $log_2\;N$, whereas the average entropy of smaller groups $(W_1,\;W_2,...W_m)$ is as small $(as\;(\sum\limits^m_{i=1}\;H(W_i))/m$. Retrieval efficiency is a measure of information system's performance, which is largely affected by goodness of index. If all and only documents evaluated relevant to user's query can be retrieved, the information system is said $100\%$ efficient. Document file W may be potentially classified into two sets of relevant documents and non-relevant documents to a specific query. After retrieval, the document file W' is reclassified into four sets of relevant-retrieved, relevant-not retrieved, non-relevant-retrieved and non-relevant-not retrieved. It is shown in the paper that the difference in two entropies of document file Wand document file W' is a proper measure of retrieval efficiency.

• 대한수학회지
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• 제32권2호
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• pp.171-181
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• 1995

Nielsen coincidence theory is concerned with the estimation of a lower bound for the number of coincidences of two maps $f,g: X \longrightarrow Y$. For this purpose the so-called Nielsen number N(f,g) is introduced, which is a lower bound for the number of coincidences ([1]). The relative Nielsen number N(f : X,A) in the fixed point theory is introduced in [3], which is a lower bound for the number of fixed points for all maps in the relative homotopy class of f:(X,A) $\longrightarrow$ (X,A), and its estimation is given in [5].

• 한국산학기술학회논문지
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• 제15권7호
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• pp.4148-4156
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• 2014

본 연구의 목적은 국가 연구개발(R&D) 성과측정지표의 개선안을 새로운 관점을 통해 제시하는 것이다. 정부는 R&D 패러다임을 기존의 추격형에서 선도형으로 전환하고자 하고 있다. 이에 기존 성과평가의 문제점을 살펴보고 기존 문헌 연구를 통해 국내외 연구기관 정부기관의 성과 평가안을 살펴보았다. 특히 국내외적으로 창조 혁신지표군을 참조하였고 국가혁신 및 R&D 생태계라는 개념에 주목하였다. 이론 체계로 D'Aveni의 혁신경쟁이론(Hypercompetition theory)을 차용하여 새로운 성과평가지표를 제시하였으며 국내 R&D 성과평가 전문가를 대상으로 AHP 분석을 수행하였다. 지표별 우선순위 결과 및 의미는 본문에서 상세히 밝히고 있다. 본 연구는 새로운 관점의 이론적 틀을 바탕으로 창조 혁신지표군을 참조하여 국가 R&D 성과지표군을 제안하였고 실증적 검증을 거쳐 지표별 우선순위를 제시했다는 점에서 이론적 그리고 실무적으로 공헌하고 있다.