• Annual Conference of KIPS
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• 2010.11a
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• pp.992-995
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• 2010

본 논문에서는 TCP Vegas의 혼잡 제어 알고리즘을 개선하여 전송 효율을 높이는 TCP AD-Vegas를 제안한다. 현재 널리 사용되는 Reno 방식은 Additive Increase Multiplicative Decrease(AIMD) 기반의 혼잡제어 방식으로 혼잡이 생길 경우 세션의 전송 크게 줄이는 기법이다. 최근 네트워크 인프라 증가로 큰 대역폭을 사용할 수 있게 되었으나, TCP Reno의 소극적인 혼잡 윈도우 조절로 충분한 전송 효율을 얻지 못하고 있다. 본 논문에서는 RTT를 이용하여 혼잡 정도를 판단하고 혼잡 윈도우를 조절하는 TCP Vegas를 개선하여 TCP의 전송 효율을 높일 수 있는 새로운 알고리즘을 제안한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.532-542
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• 2020

Due to abnormal weather conditions such as high temperature, the management of greenhouse rose farms is getting worse. In order to enhance the competitiveness of these farms, new measures are needed to improve their management performance. Therefore, this study suggests alternatives to improve the efficiency and productivity by identifying the causes of inefficiency of greenhouse rose farms in terms of management performance analysis through DEA analysis and MPI analysis. As a result of DEA analysis, the average TE of farmers increased from 0.867('16) to 0.905('17), but decreased to 0.850 in 2018, indicating that it was inefficient. In order to increase the management efficiency of farmers, efforts to preferentially reduce the costs (equipment, employment labor, fertilizer, facilities, seeds) that cause inefficiencies are needed. As a result of MPI analysis, TECI decreased from 1.044(T2) to 0.939(T3), which was the cause of the MPI decrease, and the TCI was rather increased from 0.958(T2) to 0.969(T3). In other words, it means that the decrease in productivity is due to insufficient utilization of potential production technology rather than the slowing of technological progress. This implies that it is important to provide technical guidance on utilization after technology dissemination.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.145-150
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• 2020

The provision of information on the profitability and efficiency during the transition from growing rice to substitute crops is an essential task for the proliferation and settlement of the production adjustment system. First, the profitability of the soybean + barley cropping system was analyzed. The average income of the farms with the soybean + barley cropping system surveyed was 868,000 Won, with an income proportion of 55.1%. With earned income that is approximately 1.7 times higher than that of growing only rice, it is determined to be more profitable. Then, the efficiency of the farms was analyzed through DEA analysis. The efficiencies of the farms were found to include the CCR model (0.927815) and the BCC model (0.97544). It was also found that there are 10 CCR and 14 BCC results with an efficiency value of 1. With an efficiency value of more than 0.9 on average, it can be deemed as efficient management in general. In addition, by presenting a proposal for the improvement of inefficient farms, the target value was provided in order for inefficient farms to become efficient farms.

• Journal of Korean Society of Transportation
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• v.25 no.3
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• pp.55-63
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• 2007

This paper analyzes the relative efficiency of Korea's logistics industry with the DEA-ANP model from 2003 to 2005. To measure the efficiency, this paper used the numbers of employees, fixed assets. total capital. and operating costs as input factors and sales amounts and net incomes as output factors. The average efficiency score of the entire logistics industry is 0.175, so most logistics companies in Korea should improve their current inefficiencies. The industry with the highest efficiency score is marine transportation. with an average three-year efficiency score of 0.3692. In terms of sales and high efficiency. most of the highest-ranked companies belong to the marine transportation industry, so marine transportation has the most influence on raising the efficiency score of Korea's logistics industry. To improve the inefficiency of inputs that exists overall in the logistics industry it is necessary to control excessive numbers of employees. To improve the amount of sales, it is necessary to make a policy of satisfying various logistics demands, continuous investments, and attracting foreign logistics demand: such things will help strengthen the international competitiveness of Korea's logistics industry.

• Journal of Practical Engineering Education
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• v.12 no.1
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• pp.213-230
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• 2020

Until now, various educational budgets, facilities, and programs have been put into school education, but the results have not been clearly evaluated. This study presents a model to analyze the effectiveness of educational support for students in high schools across the country. In this model, we first use EM cluster analysis to make clusters with similar inputs for school operation, and then calculate the relative efficiency in each cluster by using Network DEA analysis. The Network DEA analysis has a two-stage structure where the first stage uses six inputs in terms of school infrastructure to generate outputs such as the number of academic persistence. In the Network DEA analysis, the second stage uses 10 inputs in terms of school programs to generate outputs such as the number of enrollees to higher learning and the number of employees and per capita usage of library as the connection variable. Based on the efficiency analysis results, Tier analysis is performed by applying the Euclidean distance to select targets for benchmarking. In this study, we applied the model to analyze the efficiency of educational support by collecting data regarding student education support in general and vocational high school nationwide. The stepwise benchmarking method proposed that the target be selected for efficiency improvement step by step, taking into account inefficient school elements to complement the problem of the choice of benchmarking targets. Based on this study, it is expected that schools with low efficiency of educational support for students will be used as basic data for stepwise benchmarking for efficient operation of educational support for students.

• Journal of Korea Port Economic Association
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• v.26 no.2
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• pp.82-98
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• 2010

The purpose of this paper is to suggest the efficiency measurement way of Korean seaport by using Average Index Transformation model of fuzzy DEA(Data Envelopment Analysis). Two inputs[cargo handling capacity, and berthing capacity], and outputs[cargo handling amount, and the number of ship calls] are used in 1995 and 2004 for 26 Korean seaports. Empirical main results are as follows: First, Tongyung, Gohyun, Okpo, and Sogcho Ports are efficient, and Yeasu Port shows the high efficiency level over 95% under input oriented CCR model. Gohyun and Sogcho Ports showed the most efficient score under average index transformation model. Okpo and Yeasu Ports increased their efficiency scores as the lamda(λ) values are up. The empirical results of fuzzy DEA average index transformation model for Wando, Yeasu, and Seoguipo ports showed that if the lamda values are higher, the efficiency scores are also higher. The main policy implication based on the findings of this study is that the management manager of Ministry of Land, Transport and Maritime Affairs in Korea should introduce the fuzzy DEA average index transformation model for deciding the size of inputs including the port investment amount and evaluating the port efficiency.

• Journal of Korea Port Economic Association
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• v.37 no.2
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• pp.91-105
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• 2021

The current increasing size of container vessels affects the container port's situation. The containerization has changed the inter-modal handling process, which brought more flexibility and comfortableness in the shipping industry sector. Thus, it is very crucial to analyze the efficiency of container ports in the regional sphere. Such kind of efficiency analysis provide a powerful management tool for port operators and shipping managers in the Mediterranean market, and it also helps to form an information for planning new regional and national port operations. This paper aims to analyze the ports' technical efficiency of Mediterranean major container ports. It is conducted to establish the model of port performance and efficiency through the empirical test of the various factors. Regarding to the panel data collected from the 48 DMUs (decision making units), this study attempts to provide the empirical basis of the port efficiency relative to another factors in the total port performance. Due to the complexity of the various activities carried out at container ports, the study focuses only on the technical efficiency at the level of the Mediterranean container port. Unlike the practice of cross-sectional data analysis, originally established by Charnes et al. (1985), the panel data in DEA window analysis applications are used. The main focus of this study is the relative technical efficiency of 12 container ports from 7 countries in the Mediterranean market. The selection of ports under study is based on their high handling capability and rankings in World Top 100 (Containerization International, 2018).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.122-124
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• 2014

Currently mobile game market has expanded rapidly due to the development of smart phone. In addition, mobile web board game has been developed consistently. However, several problems appear in users' usability. That is why the user who plays game do not satisfy in aspect with usability. The objective of this research analyses the factors to investigate the efficiency and the accuracy among usability those in web board game based on smart phone. We conduct to research the efficiency and the accuracy in traditional usability literatures and derive the proper usability factors based on smart phone. We expect to provide the guideline related on usability in mobile board game in the future.

• Journal of agriculture & life science
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• v.45 no.6
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• pp.279-289
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• 2011

The purpose of this study is to estimate efficiency of item-based agricultural cooperative by using Data Envelopment Analysis. A proposed method employs a bootstrapping approach to generating efficiency estimates through Monte Carlo simulation resampling process. The technical efficiency, pure technical efficiency, and scale efficiency measure of item-based agricultural cooperative is 0.80, 0.87, 0.93 respectively. However the bias-corrected estimates are less than those of DEA. We know that the DEA estimator is an upward biased estimator. In technical efficiency, average lower and upper confidence bounds of 0.726 and 0.8747. According to these results, the DEA bootstrapping model used here provides bias-corrected and confidence intervals for the point estimates, it is more preferable.

• Journal of the KSME
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• v.50 no.7
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• pp.41-46
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• 2010

이 글은 수송에너지 분야의 효율성 향상 기술에 대한 전망을 다룬다. 먼저 현재 자동차 산업/시장의 환경과 고효율 기술들을 소개한다. 아울러 항공과 선박 부문 기술의 현황/발전 가능성을 분석한 뒤 미래 수송에너지 시장에 대한 종합적인 대응 방안에 대해 요약하고 있다.