• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.1
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• pp.51-60
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• 2012

Optimization procedures of performance analysis for ORC(Organic Rankine Cycle) system are established to the characteristics of low temperature heat sources such as open-type and closed-type. Effective heat recovery and heat extraction related to maximum power of the cycle as well as heat quality and thermal efficiency must be considered in the case of the open-type low temperature heat source. On the other hand, in the case of the closed-type low temperature heat source, only thermal efficiency is important due to constant heat input. In this study, thermal efficiency and exergy efficiency representing a level of close to Carnot cycle are studied, as useful index for the optimization of the ORC system. To validate the results of cycle analysis, those are compared with appropriate experimental data of ORC system as a thermal efficiency point of view.

• Journal of the Korean Operations Research and Management Science Society
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• v.41 no.1
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• pp.99-111
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• 2016

This paper presents a framework to analyze the change in the research and development (R&D) efficiency of government-funded research institutes (GRIs) in Korea. Cumulative data envelopment analysis/Malmquist index method is utilized to analyze the changes in R&D efficiency of GRIs. Data analysis of the R&D activities of 10 GRIs in Korea Research Council of Fundamental Science & Technology showed that the average R&D efficiency of the 10 GRIs improved from 2009 to 2013. However, the efficiency of a few GRIs decreased in terms of the catch-up index. The proposed framework can help management teams diagnose the current state of R&D activities and determine the efficacy of strategic actions by comparing efficiencies in the past.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.6
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• pp.209-220
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• 2010

Evaluating performance in public sector aims to enhance the efficiency of organizations. Evaluating the efficiency which is the ratio between input and output, organizations set directions of improvement. This research applied Data Envelopment Analysis(DEA) useful to evaluating the efficiency of organizations in public sector. Decision Making Units(DMU) of this research are 21 Information Security Organizations of departments/agencies. As the results, the mean of efficiency score of 21 DMUs is a little more than 50%. Means of departments(8 DMUs) and agencies/committees(11 DMUs) are similar to the total efficiency score. For these results, the decision makers of the information security organizations in public sector have to strive to improve the inefficiency.

• Korea Journal of Hospital Management
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• v.22 no.2
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• pp.44-57
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• 2017

The objective of this study is to investigate financial integrity strategies for sustainable development of local public medical centers, and particularly focus on seeking ways to enhance its financial efficiency and publicness. The data which was collected from 33 local public medical centers was analyzed by Data Envelopment Analysis to measure its financial efficiency. Then, Matrix Analysis was used to examine the association of financial efficiency and publicness of local public medical centers with related factors. In the aspects of facilities and location, according to the results, the local public medical centers which have larger number of available hospital beds or located in bigger cities were examined to have higher degree of publicness. In the aspect of human resources, greater number of doctors made both financial efficiency and the degree of publicness decreased, whereas higher participation rate of educational program for doctors affects increasing its financial efficiency and publicness. Lastly, in the aspect of costs, higher labor, material, and administrative cost diminished financial efficiency, but enhanced the degree of publicness. Based on these results, this study concluded that enhancing the publicness of local public medical centers should be pursued by increasing the accessibility with better facilities and location, and also concurrently organizing rational expenditure structure with appropriate cost investment to the resources of local public medical centers. Also, it is necessary to enhance both financial efficiency and publicness simultaneously by improving the quality of health care services through the educational programs for medical staffs.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.6
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• pp.95-107
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• 2020

We analyze the performance of South Korea wholesalers and retailers during the period when COVID-19 emerged and began to spread in South Korea. Specifically, we choose operational efficiency as a proxy variable for reflecting corporate performance and apply stochastic frontier analysis for estimating operational efficiency. Importantly, in order to examine the impact of the COVID-19 period (Q1 to Q2 2020) on operational efficiency, we consider the quarterly fixed effect corresponding to the COVID-19 period. Our findings include: (ⅰ) the average level of operational ffficiency is approximately 0.7138 during the analysis period (Q1 2019 to Q2 2020); (ⅱ) the fixed effect of the COVID-19 period on operational efficiency is not significant; and (ⅲ) operational efficiency is positively correlated with the scale of the company. Moreover, from an academic perspective, we make a contribution by examining the relationship between the operational efficiency as a firm-level variable and the COVID-19 period as a macroeconomic variable.

• Journal of Korea Technology Innovation Society
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• v.3 no.3
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• pp.36-52
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• 2000

This study takes an issue of efficiency analysis in the presence of network effect utilizing the DEA (Data Envelopment Analysis) framework. Network effect has important policy implication for the regulation of local monopolies which undertake their business through physical network, such as electricity, natural gas, local telephony, etc. If the difference in spatial condition between companies is not controlled properly, the performance comparison and associated incentive regulation bear significant bias. In this study, we propose a methodology to measure the true managerial or technical efficiency apart from efficiency difference accruing from the difference in spatial condition. A series of modified DEA efficiency models are combined to investigate the extent of exogenous and endogenous efficiency component in the Korean natural gas distribution companies. Empirical results show that the network effect plays significant role in determining superficial performance difference.

• Proceedings of the Korea Database Society Conference
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• 2008.05a
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• pp.321-338
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• 2008

Information and communication industry, which shows rapid growth rate, is now leading the global economic growth, contributing a ripple effect on general business and economic structure. It is said that information and communication industry enables swift economic growth taking a role as a basic industry of information-oriented society. Especially, rapid technical innovation promotes mutual growth of other related industries and it is technology-intensive. The purpose of this research is to analyze the management efficiency of information and communication industry using DEA method, and finally suggest numerical value for inefficient organizations to improve their efficiency. CCR-I, BCC-I efficiency and RTS(Returns to scale) of 29 companies engaged in information and communication industry was evaluated. With the results, I suggested model companies for benchmarking in information and communication industry. To summarize, 7 companies were selected with CCR-I efficiency rate 1, and 12 companies with BCC-I efficiency rate 1. RTS was finalized with 8 IRS companies, 10 DRS companies, and 11 CRS companies.

• Journal of the Korea Safety Management & Science
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• v.9 no.5
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• pp.125-133
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• 2007

Everyone knows how much the company business goal is achieved is the most important to all companies. In order to maximize the business performance, many companies have introduced a diversity of management innovation activities. The effect of business performance is important in the business activity, but an efficiency of output-to-input concept is significantly important. Each year, companies have managed the business through a sum of performance. In terms of the efficiency of business performance, the management is importantly managed. In the efficiency of business performance, there are the main items including the total assets, employees, and operating expenses as the input. As the output, there are the main items of sales, current term's net income. This study is intended to calculate the business efficiency through DEA analysis for companies' business performance, and to study in order for the efficiency of business performance to be considered when the companies establish the mid and long term business plan.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.2
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• pp.108-119
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• 2015

This study intends to propose a non-oriented DEA based game cross-efficiency approach for supplier selection. With a discussion on the choice of DEA models and approaches that are most appropriate for supplier selection, we propose a game cross efficiency model based upon the non-oriented variable returns-to-scale RAM DEA by adapting the existing game cross efficiency model based upon the oriented constant returns-to-scale CCR DEA. We develop the RAM game cross efficiency model and a convergent iterative solution procedure to find the best game cross efficiency scores that constitute a Nash equilibrium. We illustrate the proposed model with two data sets of supplier selection, and demonstrate that significantly different results are obtained when compared with the existing approaches.

• Journal of the Optical Society of Korea
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• v.17 no.1
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• pp.22-26
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• 2013

The author analyzes the luminous efficiency of the phosphor-conversion white light-emitting diode (LED) that consists of a blue LED chip and a yellow phosphor. A theoretical model is derived to find the relation between luminous efficiency (LE) of a white LED, wall-plug efficiency (WPE) of a blue LED chip, and the phosphor absorption ratio of blue light. The presented model enables to obtain the theoretical limit of LE and the lower bound of WPE. When the efficiency model is applied to the measured results of a phosphor-conversion white LED, the limit theoretical value of LE is obtained to be 261 lm/W. In addition, for LE of 88 lm/W at 350 mA, the lower bound of WPE in the blue LED chip is found to be ~34%. The phosphor absorption ratio of blue light was found to have an important role in optimizing the luminous efficiency and colorimetric properties of phosphor-conversion white LEDs.