• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.924-930
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• 2018

The objective of this study was to investigate heating performance characteristics of electric heat pump system in a fuel cell electric vehicle (FCEV). In order to analyze heating performance characteristics of electric heat pump system with plate-type heat exchanger using stack coolant to evaporate the refrigerant, R-134a, each component was installed and tested under various operating conditions, such as air inlet temperature of inner condenser and compressor speed. When the air inlet temperature of inner condenser was varied from $0.0^{\circ}C$ to $-20.0^{\circ}C$, heating capacity was not quite different due to similar temperature gap between inlet and outlet of inner condenser with electric-driven expansion valve (EEV). However, COP increased until certain EEV opening, especially under 45.0%, because of decreasing power consumption. According to the compressor speed variation from 2,000 to 4,000 RPM, heating capacity and COP were found to have opposite trend. In the future works, stack coolant conditions as the heat source for tested heat pump system were analyzed with respect to heating performance, such as heating capacity and COP.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.7
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• pp.20-25
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• 2010

With the diversification of distribution facilities, existing distributed generation can be subdivided into Microgrids, which are smaller units for application. These Microgrids, subdivided as such and connected to distribution systems, should operate under driving plans that will ensure their economic efficiency and, accordingly, the configuration of those distribution systems that include Microgrids should also be changed. The perception of the necessity to secure the economic efficiency of distribution systems is gradually increasing and studies intended to assess the economic efficiency of Microgrids and Smartgrids are ongoing. In this paper, the power generation capacity of an economically operative Microgrid was calculated using the MonteCarlo simulation, which is a method based on the probability theory considering the power generation cost of Microgrids linked with power supply systems and reverse sales costs, etc., and an optimum distribution systems was configured based on the results of these calculation.

• IE interfaces
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• v.15 no.4
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• pp.325-337
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• 2002

In this study we consider the problem of production planning of TFT-LCD(Thin Film Transistor - Liquid Crystal Display) production factory. Due to the complexities of the TFT-LCD production processes, it is difficult to schedule the production planning, and the study about automated scheduler is insufficient. In addition, the existing production method is a Push-System to raise the operation rate with expensive equipment, that has the problem to satisfy the due-date. This study presents an algorithm having a concept of Pull-System that satisfies the due-date and considers specialties of TFT-LCD production process. We make MPS(Master Production Schedule) according to the sales order, and present algorithms for scheduling about In/Out plan considering factory capacity, line balancing, material requirement, and inventory level of all Array, Cell, and Module processes. These algorithms are integrated as an automated production system, and we implement them in the actual TFT-LCD factory circumstance.

• Environmental and Resource Economics Review
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• v.9 no.2
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• pp.349-371
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• 2000

Data Envelopment Analysis model is a linear programming based technique for measuring the relative performance of organizational units where the presence of multiple inputs and outputs makes comparison difficult. A common measure for relative efficiency is weighted sum of outputs divided by weighted sum of inputs. DEA model allows each unit to adopt a set of weight that shows it in the most favorable light in comparison to the other unit. In this paper, we present the mathematical background and characteristics of DEA model, and give a short case study where we apply the DEA model to evaluate the relative efficiencies of 51 global electricity companies. The technical efficiency and scale efficiency are also to be investigated. Generating capacity and the number of employees are used for input data, and revenue, net profit and electricity sales are used for output data. We find that the companies with 100% relative efficiency are only 9 among 51 electricity companies. And the technical and scale efficiency of KEPCO is 98.7% and 78.89%, respectively. This means that the inefficiency of KEPCO is caused by the scale inefficiency. The analysis shows that the employees should be decreased by 15% at minimum to get the 100% efficiency. The result suggests that KEPCO needs the structural reform to improve the efficiency.

• Environmental and Resource Economics Review
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• v.16 no.4
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• pp.763-779
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• 2007

The combined heat-and-power (CHP) plant is recently suggested as an effective resolution in response to recent rising oil prices and the Kyoto Protocol. This research provides a model for economic appraisal to evaluate CHP investment. Real option model is developed to incorporate a case where the investment is irreversible and underlying revenue is stochastic. The analysis shows that power plant capacity more than 40 Gcal makes CHP investment profitable while the results may vary 10 modest level with respect to investment cost, heat sales price and discount rate.

• Journal of the Korea Fashion and Costume Design Association
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• v.17 no.3
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• pp.149-158
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• 2015

More weight is given today to the role and capacity of fashion shopmasters who stand in direct contact with customers at department stores. The present study examines relationship between the stress factors and the job satisfaction by fashion shopmasters. The questionnaires was prepared 300 fashion shopmasters who work at fashion brand shops for ladies' formal and casual dress in department stores located in Chungcheong provincial areas from Aug. 5 to 23, 2013. Out of the distributed questionnaires, 270 were returned and 256 were put to the final analysis after excluding those that were replied unfaithfully. The second stage was to collected data underwent frequency analysis, factor analysis, reliability analysis and regression analysis to determine the effects of variables by using SPSS 18.0. Fashion shop masters are therefore requested to have exact understanding to their role as retail sales professionals, fashion advisers and experts of fashion shop management, to become well aware of their job in detail, to apply such knowledge to their practical job performance and to make personal efforts to promote their status as fashion shop masters.

• The Journal of Fisheries Business Administration
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• v.43 no.2
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• pp.51-66
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• 2012

The purpose of this study is to present a new business performance model suitable for marin repair business. For this propose we have used survey datas gathered on several input and output factors from Marine engin repair companies Yeong-Do Gu. Gathering these the survey results we estimated the efficiency of each company through DEA method. The results of the analysis can be summarized as follows ; First, the result of the analysis showed 7 out of 24 DMU are not efficient companies. On the other hand 17 of them are efficient as the efficient output analyzes showed. Second, by analysing the results we could see significant differences between group companies, Ltd with a private companies with share on average efficiency in utilization. Third, two of the private companies are more effective and 6others were selected revisit and interview on the analysis. As a result inefficient DMU compared to efficient DMU and showed that they invest more on manpower in the field of sales and professional managers and techicians. Also, lots of effort devoted in order to standardize production by building capacity and environment management to improve welfare of the workers.

• Journal of Korean Society for Quality Management
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• v.38 no.3
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• pp.463-474
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• 2010

In this study, we evaluate the efficiency of Construction Industry using Data Envelopment Analysis(DEA). Since the Construction Industry has been traditionally operated through competition, it is important to measure the efficiency. In this paper, we empirically analyze the Efficiency of the 50 Korean Construction Industry. In detail, we used the scale of efficiency in order that efficiency cannot be affected by the total technical efficiency of each company and the scale of DMU by applying CCR or BBC model. Also, we analyzed the changes of measurement DEA model score. we adopted the basic DEA, RTS Region and MPSS(Most Productive Scale Size) method which are combined with efficiency measurement model in order to analyze the operational status. Furthermore, by complementing the shortfalls of the scale efficiency value of the DEA Model, RTS Region Model can be recommended to be appropriate in the evaluation of ideal input/output Quantity. In particular, input variables are total assets, construction capacity, the technical staff and output variables are sales volume, operating income. The result of RTS Region and MPSS shows that 9 DMUs of the efficiency frontier in the Construction Industry are analyzed to be relatively efficient DMUs, and 41 DMUs are analyzed to be inefficient DMUs, and finally inefficient DMUs are separated with Region 1 and Region 6.

• Journal of ILASS-Korea
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• v.25 no.1
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• pp.34-39
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• 2020

Automotive manufacturers are applying technologies for greenhouse gas reduction such as vehicle weight reduction, engine downsizing, direct injection technology, variable valves and transmission performance improvement to achieve the targets for enhanced greenhouse gas and fuel consumption efficiency. In this paper, compared and analyzed greenhouse emissions according to engine capacity, engine displacement, curb weight and sales volume of hybrid and internal combustion engine passenger vehicles. Hybrid emit 32~39% less greenhouse gas than internal combustion engines through the combined mode test method. Hybrid electric vehicle's curb weight was about 7% heavier on average for the same engine displacement, while greenhouse gas was about 36% lower. It was confirmed that in order to reduce the emission of pollutants of greenhouse gases as well as the air pollutants, it is necessary to expand the supply of eco-friendly vehicles.

• The Journal of Fisheries Business Administration
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• v.43 no.1
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• pp.11-18
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• 2012

This study is aimed to estimate a dynamic productive efficiency by vessel of large purse seine fishery and analyze changes of them over times using a window/DEA method. In addition, based on estimation results, it aims to suggest production management implications for an viable development of fisheries. Results indicated that an annual efficiency change of large purse seine fishery was estimated at 0.77 for 2007~2008, 0.83 for 2008~2009, and 0.77 for 2009~2010, showing a decreasing trend. As returns on sales of vessels of large purse seine fishery showed a decreasing trend, the degree of efficiency of a vessel might be closely related to the fishing profitability. The Window/DEA method was used in this study to estimate the efficiencies of vessels for large purse seine fishery. This method is well known and widely used to analyze the dynamic efficiency and it can provide useful implications for management of input factors. As a limitation of this study, it was not able to provide detailed management ways to reduce inefficiencies. However, they can be investigated with data on managerial factor, human factor, distribution factors as a future study.