• Journal of Power Electronics
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• 제3권3호
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• pp.175-184
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• 2003

In this paper, a new control scheme of Class-E inverter for reducing the crest factor of electronic ballasts for fluorescent lamps using Pulse-Frequency-Modulation (PFM) is Introduced The lifetime of the lamps is guaranteed by decreasing the lamp crest factor and also voltage stress of the switch is significantly decreased by a new scheme although conventional Class-E Inverter is used In this paper. The proposed PFM control scheme didn't use any auxiliary circuit. The proposed control strategy is executed by feeding back the Input voltage, and the zero-voltage-switching (ZVS) is ensured by maintaining constant turn-off time of the switch Therefore, the control principles of proposed method are explained in detail and its validity is verified through several simulations and experimental results.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3595-3603
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• 2022

Nuclear safety-class DCS is used for nuclear reactor protection function, which is one of the key facilities to ensure nuclear power plant safety, the maintenance for DCS to keep system in a high reliability is significant. In this paper, Nuclear safety-class DCS system developed by the Nuclear Power Institute of China is investigated, the model of reliability estimation considering nuclear power plant emergency trip control process is carried out using Markov transfer process. According to the System-Subgroup-Module hierarchical iteration calculation, the evolution curve of failure probability is established, and the preventive maintenance optimization strategy is constructed combining reliability numerical calculation and periodic overhaul interval of nuclear power plant, which could provide a quantitative basis for the maintenance decision of DCS system.

• 대한수학회지
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• 제47권1호
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• pp.63-70
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• 2010

In this paper, we develop a nonmonotone spectral memory gradient method for unconstrained optimization, where the spectral stepsize and a class of memory gradient direction are combined efficiently. The global convergence is obtained by using a nonmonotone line search strategy and the numerical tests are also given to show the efficiency of the proposed algorithm.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.985-988
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• 1993

An alternative approach to the design of application-driven fuzzy systems is proposed. A broad class of fuzzy systems applications requires a certain fuzzy partition of the input space while it demands for simple numerical quantities. For this class, a dedicated fuzzy system archictecture is presented and a design strategy is proposed. Both the single-input/single-output and multi-input/multi-output cases are considered. Numerical analysis are complete illustrating several aspects of the proposed framework.

• 디자인학연구
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• 제17권4호
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• pp.385-396
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• 2004

1950년대부터 시작된 한국의 디자인 진흥은 국가 경제의 발전과 맥락을 같이하며 발전되어왔다. 초창기에는 주로 외국의 디자인 진흥 전략을 베끼는 모방자 수준이었으나, 점차 수정자와 개선자를 거쳐 선구자로서의 위상을 점하고 있다. 이 연구는 이처럼 빠른 기간동안에 후발국의 불리함을 극복하고 디자인선진국을 지향하고 있는 한국의 디자인 진흥 전략을 고찰하였다. 디지털시대를 맞아 나타나고 있는 환경의 변화, 디자인 진흥 본질, 세계디자인 진흥의 발전과정 및 현황 등이 다각적으로 다루어졌다. 이를 토대로 디자인산업기본법(가칭)제정, 한국디자인진흥원(KIDP)의 자생력 강화, 한국디자인진흥재단(가칭)의 설립, 한국디자인단체총연합회(KFDA)의 위상 강화 등 새로운 도약을 위한 과제가 도출되었다.

• Journal of Information Technology Applications and Management
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• 제19권1호
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• pp.47-59
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• 2012

A number of organizations have had big interests in studies concerning leadership and in academic areas, in not only management but also psychology. Until now, leadership has been accentuated by managers or team leaders especially. Recently, however, the concept of self-leadership directing one's own activities through self-control or self-management is being focused on in practices and in academia. This study is to investigate the influence between self-leadership strategies and learning performance in IT classes mediated by attitude of attendance focused on the social science students in two universities (Korea (121 samples) and India (106 samples)). And this research tried to compare difference between two university students. Research results can give us direction of task-taking attitudes in firms or learning attitudes in teaching organizations and implications to human resource managers who are in charge of improving learning performance or productivity.

• 한국환경복원기술학회지
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• 제5권5호
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• pp.67-75
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• 2002

This study was carried out to introduce current status to discuss erosion control strategy for the conservation of stream valley ecosystem. To restore stream valley ecosystem, we should establish restoration plans to keep the original shape of stream. It is necessary to use environmentally sound materials with conservation of valley stability. Valley construction for erosion control works should be evaluated continuously based on concepts of conservation and development of stream valley ecology. It is categorized in point of the important of class of stream valley conservation ahead planning and constructure. We suggest that the development of stream valley construction needs to prevent mass movement of soil sediments. In addition, it is established the basal strategy to protect macro and micro aquatic organisms in stream valley ecosystem.

• 한국학교수학회논문집
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• 제4권2호
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• pp.103-113
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• 2001

The teaching-learning method utilizing Web makes it possible for the students take the initiative in any field and offers the teaching strategy, methodology and teaching-learning materials suitable for students' ability and standard. The purpose of this study is to investigate the characteristics of WBI in mathematics class for the effective teaching and learning focusing on the unit 'Function' in the 1st grade of middle school and verify its effectiveness by developing the WBI programs which can progress learning achievement and applying them to math class. Two hypotheses were established for this study. Hypothesis 1 : There will be meaningful difference between the group that studies under WBI and the one that doesn't, Hypothesis 2 : There will be meaningful difference in the attitude and interest toward learning between the group that studies under WBI and the one that doesn't. In order to find out the result, I have made a comparative analysis through t-verification on the object of two classes of the 1st grade in P middle school that I have been working for. The result shows that the class utilizing WBI is more effective than the traditional lecture-oriented class since there is a meaningful difference between the control group and experimental one and also that the class based on WEB has a great influence on students' interest and positive attitude toward math class.

• 한국수학교육학회지시리즈A:수학교육
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• 제55권3호
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• pp.299-316
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• 2016

The abilities for 21st learners have recently changed and learners' engagement is emphasized. In flipped classroom, students learn the prerequisite concepts of the lecture online in advance and perform various types of activities based on interaction and engagement. As students in flipped classroom construct knowledge actively, students' engagement is very important. Therefore, I conducted a research of flipped mathematics class to help teachers to better understand students' engagement in flipped mathematics class. The flipped mathematics class was conducted for about 3 weeks with 29 middle school students and one teacher. Video and audio recordings, completed student worksheets and interview data were collected and analyzed using the qualitative method. The results of this study showed that students' engagement is influenced by diverse factors. Engagement factors were categorized by teacher factors, community factors, material factors, tasks and strategy factors, classroom culture factors. Each factor facilitates or suppresses behavioral, emotional, cognitive, agentic engagements, and sometimes several factors are related. The results of this study increase understanding of engagement through the example of a case study on flipped mathematics class.

• 한국병원경영학회지
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• 제16권4호
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• pp.35-66
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• 2011

This study analyzed efficiency by utilizing DEA analytical technique centering on materials for 2009 of 20 major university hospitals in capital area. Input variables were utilized professor & full-time doctor, resident, nurse & number of bed hospitals. Output variables were analyzed by dividing number of annual outpatients & number of annual inpatients, and annually total outpatient profit & inpatient profit into a model of the standard for number of patients and the standard for medical profit. DEA analysis was elicited efficiency score by applying CCR, BCC, BFG, scale profit, and SE model. Through t-test after eliciting efficiency score, the implications were suggested by comparing efficiency between DMU in Seoul and DMU in capital area, by comparing between high-class general hospitals and general hospitals, and by comparing between high-class general hospitals in Seoul and 5 big hospitals. As a result of analysis, the major university hospitals in capital area showed high efficiency as a whole close to "1," but indicated low efficiency relatively in CCR field. Thus, the expansion in scale within capital area was indicated to reach the limit. Second, in a model of analyzing the standard for number of patients, the medical institutions, which are being operated efficiently, were indicated to be 10 DMUs. In the standard for medical profit, 12 DMUs were analyzed to be operated efficiently. Third, the efficiency in general hospital was higher than high-class general hospital. Thus, the efficiency of operation was indicated to be more important than scale. Also, large high-class hospitals(big 5) where are located in downtown Seoul showed the higher efficiency than other general high-class general hospitals, but were indicating very low efficiency in some DMUs. Fourth, as a result of generalizing and evaluating the number of patients and the medical profit, the efficient DMU was indicated to be more when analyzing on the basis of medical profit than the standard for number of patients. Thus, major university hospitals in capital area were indicated to make more effort for section in medical profit. Based on the analytical results of efficiency, a strategy for reinforcing efficiency in inefficient DMU was indicated to be needed a strategy of creating customers for promoting number of patients and a strategy for making operation efficient for increasing profitability.