• Journal of Energy Engineering
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• v.12 no.4
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• pp.274-280
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• 2003

This paper presents a Case-Sort method to solve the unit commitment problem using database in electric power systems. The formulation of the unit commitment nay be described as nonlinear mixed integer programming. However, it is hard to optimize a problem with discrete and continuous variables in a large-scale system at the same time. The Case-Sort method is based on the unit［MW］generation cost considered drive hour. Then, this paper shows effectiveness and economical efficiency of the proposed algorithm.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.161-163
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• 2001

This paper presents a Case-Sort method to solve the unit commitment problem using database in electric power systems. The formulation of the unit commitment may be described as nonlinear mixed integer programming. However, it is hard to optimize a problem with discrete and continuous variables in a large-scale system at the same time. The Case-Sort method is based on the unit [MW] generation cost considered drive hour. Then, this paper shows effectiveness and economical efficiency of the proposed algorithm.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1140-1142
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• 1998

This paper presents object-oriented dynamic programing formulation of the unit commitment problem. This approach features the classification of generating units into related groups so called class. All object which share the same set of attributes and methods are grouped together in classes and designed inheritance hierarchy to minimize the number of unit combination which must be tested without precluding the optimal path. So this programming techniques will maximize the efficiency of unit commitment.

• Journal of Korean Critical Care Nursing
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• v.12 no.3
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• pp.13-23
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• 2019

Purpose : The purpose of this study was to determine whether appreciative inquiry (AI) is an effective intervention for increasing the positive psychological capital and organizational commitment of new nurses. Method : The study used a nonequivalent control group pretest-posttest design. The participants were 60 new nurses in a tertiary hospital in Seoul. The experimental group received 2 classes of AI education and in-unit AI activities. The control group received the existing education program. Results : There was no statistically significant difference in the positive psychological capital and organizational commitment between the experimental group and the control group over time. Satisfaction with the AI education scored 3.69, which was higher than the average. The reason why the experimental group members were satisfied with the program was that AI education helped them to adapt and the in-unit AI activities made staff more cooperative and the atmosphere of the unit more positive. Conclusion : When applying AI activities to new nurses to promote positive psychological capital and organizational commitment, it is necessary to provide a workshop in which the participants can fully concentrate on education and to extend the period of use to one year in order to maintain the effect of AI activities.

• Journal of Electrical Engineering and Technology
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• v.4 no.3
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• pp.323-329
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• 2009

This paper presents a new approach for thermal unit commitment (UC) using a differential evolution (DE) algorithm. DE is an effective, robust, and simple global optimization algorithm which only has a few control parameters and has been successfully applied to a wide range of optimization problems. However, the standard DE cannot be applied to binary optimization problems such as UC problems since it is restricted to continuous-valued spaces. This paper proposes binary differential evolution (BDE), which enables the DE to operate in binary spaces and applies the proposed BDE to UC problems. Furthermore, this paper includes heuristic-based constraint treatment techniques to deal with the minimum up/down time and spinning reserve constraints in UC problems. Since excessive spinning reserves can incur high operation costs, the unit de-commitment strategy is also introduced to improve the solution quality. To demonstrate the performance of the proposed BDE, it is applied to largescale power systems of up to 100-units with a 24-hour demand horizon.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.711-713
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• 1996

This paper proposes a unit commitment scheduling method based on Genetic Algorithm(GA). Due to a variety of constraints to be satisfied, the search space of the UC problem is highly nonconvex, so the UC problem cannot be solved efficiently only using the standard GA To efficiently deal with the constraints of the problem and greatly reduce the search space of the GA, the minimum up and down time constraints are embedded in the binary strings that are coded to represent the on-off states of the generating units. The violations of other constraints arc handled by integrating penalty factors. To show the effectiveness of the GA based unit commitment scheduling, test results for system of 5 units are compared with results obtained using Lagrangian Relaxation and Dynamic Programming.

• IE interfaces
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• v.20 no.2
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• pp.186-194
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• 2007

Recent deregulation of Korean electricity industry has made each power generation company pay more attention to maximizing its own profit instead of minimizing the overall system operation cost while guaranteeing system security. Electricity power generation problem is typically defined as the problem of determining both the on and off status and the power generation level of each generator under the given fuel constraints, which has been known as Profit-Based Unit Commitment (PBUC) problem. To solve the PBUC problem, the previous research mostly focused on devising Lagrangian Relaxation (LR) based heuristic algorithms due to the complexity of the problem and the nonlinearity of constraints and objectives. However, these heuristic approaches have been reported as less practical in real world applications since the computational run time is usually quite high and it may take a while to implement the devised heuristic algorithms as software applications. Especially when considering long-term planning problem which spans at least one year, the complexity becomes higher. Therefore, this paper proposes an explicit column generation algorithm using power generation patterns and the proposed algorithm is successfully applied to a Korean power generation company. The proposed scheme has a robust structure so that it is expected to extend general PBUC problems.

• Journal of Korean Academy of Nursing Administration
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• v.23 no.2
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• pp.151-160
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• 2017

Purpose: The aim of this study was to define the effects of relational bonds and professional authority in organizational commitment of Intensive Care Unit (ICU) nurses. Methods: A questionnaire was distributed to 200 ICU nurses working in 3 tertiary hospitals. The survey content included the Organizational Commitment Questionnaire (OCQ), Relational Bond Questionnaire (RBQ) and Schutzenhofer Professional Nurse Autonomy Scale (SPNA). Results: The score for OCQ was 2.59, for RBQ, 3.23, and for SPNA, 2.93. Organizational commitment was related to relational bonds (${\beta}=0.45$; p<.001; SE=0.08). These factors accounted for 21.6% of the variability in organizational commitment. Conclusion: Results indicate that ICU nurses' organizational commitment could be improved through increasing relational bonds and retaining experienced nurses which suggests a need to develop work systems designed to increase and maintain high relational bonds in ICU nurses.

• Journal of Korean Academy of Nursing Administration
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• v.9 no.2
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• pp.159-170
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• 2003

Purpose : This study is to confirm the relation of the value orientation of the nursing unit manager and the job satisfaction and organizational commitment of the nursing unit nurse. Method : We used the systematic questionnaires as a study tool. The contents were composed of 46 questions in total such as 4 questions of general feature, 23 value-oriented questions, 10 job satisfaction questions, and 9 organizational commitment questions. The period of data collection was from August to September 2000. Result : 1) The value of flexibility was 3.82 points (${\pm}.3788$), which is above average. The values of equalitarianism was 3.37 points (${\pm}.4422$), which is above average. 2) The leadership pattern according to the value orientation perceived by the head nurses in 6 clusters has been divided into 3 patterns of change-oriented leader, task-oriented and stability-oriented leader. 3) The nurses who worked with the change-oriented leader showed higher values of job satisfaction (F=5.941, p=O.003), and affective commitment (F=5.793, p=O.003) than those who worked with the stability-oriented leader. Conclusion : As revealed in this study, we think that we have to consider that the change-oriented leader can produce higher performance of an organization than the stability-oriented leader, and write the basic data for the educational courses of leadership development or workshops etc. in order for the nursing unit managers to play their roles for the effective ward-unit management.

• Health Policy and Management
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• v.9 no.1
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• pp.201-233
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• 1999

This study was carried out to find out the factors affecting on organizational commitment of hospital employees. For the purpose, the questionnaire-based research was done with 1280 hospital employees who were working in 2 university hospitals and 4 general hospitals located in Taegu City and Kyungpook Province from November 20, 1997 to December 22, 1997. The results of the study were summarized as follows. There were significant correlations among environmental variables, psychological variables, structural variables, vertical conflict, horizontal conflict, job satisfaction, and organizational commitment. By path analysis, variables such as pay, work involvement, work definiteness, met expectations, positive affectivity, distributive justice, job security, expectations before entering a hospital had significant positive effect on job satisfaction in order of size, while, vertical conflict, job opportunity, and horizontal conflict had significant positive effect on job satisfaction in order of size, while, vertical conflict, job opportunity, and horizontal conflict had signifecant negative effect in order of size. Variables such as job satisfaction, job security, work involvement, pay, vertical conflict, met expectations, distributive justice, positive affectivity, work unit control, job autonomy, and job routinization had significant positive direct effect on organizational commitment in order of size, while, job opportunity, job hazards and resource inadequacy had significant negative direct effects in order of size. It was found that the following variables, listed in order of size, had significant total effects on organizational commitment : job satisfaction, job security, job opportunity, work involvement, pay, met expectations, distributive justice, positive affectivity, job hazards, and work unit control. In considering abovc findings, it is recommended that programs for job satisfaction promotion, job security, decrease of intent to leave, work involvement promotion, adequate pay, met expectations, distributive justice, positive affectivity promotion, job hazards decrease, and work unit control grant should be implemented to increase organizational commitment.