• 산업경영시스템학회지
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• 제41권3호
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• pp.120-128
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• 2018

OLED Display fabrication system is one of the most complicated discrete processing systems in the world. As the glass size grows from $550{\times}650mm$ to $1,500{\times}1,850mm$ in recent years, the efficiency of Automated Material Handling System (AMHS) has become very important and OLED glass manufacturers are trying to improve the overall efficiency of AMHS. Aiming to meet the demand for high efficiency of transportation, various kind of approaches have been applied for improving dispatching rules and facility layout, while simultaneously considering the system parameters such as glass cassettes due date, waiting time, and stocker buffer status. However, these works did not suggest the operational policy and conditions of distribution systems, especially for handling unnecessary material flows such as detour. Based on this motivation, in this paper, we proposed an efficient algorithm for improving detour transportation in OLED FAB. Specifically, we considered an OLED FAB simplifying OLED production environment in a Korean company, where four stockers are constructed for the delivery of Lot in a bay and linked to processing equipments. We developed a simulation model using Automod and performed a numerical experiment using real operational data to test the performance of three operation policies under considerations. We showed that a competitive policy for assigning alternative stocker in case of detour was superior to the current dedicated policy using a specified stocker and other considered policies.

• Journal of Advanced Marine Engineering and Technology
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• 제39권4호
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• pp.399-404
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• 2015

최근 국제 원유가의 폭등으로 선박의 연료비 부담이 상대적으로 가중되고 있으며, 또한 연료의 연소과정에서 발생하는 온실가스에 대한 국제적 규제 움직임도 가속되고 있다. 이에 따라 에너지 효율 개선을 위해서 선체의 설계변경, 마찰저항을 줄이기 위한 도료개발, 엔진의 열효율을 개선하기 위한 첨가제 개발, 연료를 절감하기 위하여 저속운전 등 다양한 방법들이 적용되고 있다. 따라서 최근 고유가 시대에 선박의 고속화와 대형화 및 에너지 절감형 선형의 개발이 필수요건이 되고 있다. 또한 선체 표면의 국부 영역에서 저항 값들의 정성 및 정량적인 변화와 보다 세밀한 분석은 불가피하다고 판단되어진다. 따라서 본 연구는 에너지 효율 개선을 위한 기초연구로서 현재 운항중인 선박의 선체에서 자생하는 해양생물로 인한 마찰저항을 확인하기 위하여 도크 전 후의 엔진성능을 분석하고 그 결과를 도크와 도크사이 2.5년의 데이터와 비교함으로서 주기관의 성능, 마찰저항과 부하변화 및 연료소비량과 선속에 미치는 연구 결과 등을 보고한다.

• 한국환경보건학회지
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• 제49권6호
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• pp.295-304
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• 2023

Background: Adolescents are relatively more sensitive than adults to exposure to indoor pollutants. The indoor air quality in classrooms where students spend time together must therefore be managed at a safe level because it can affect the health of students. Objectives: In this study, three types of green-wall models were applied to classrooms where students spend a long time in a limited space, and the resulting effects on reducing PM were evaluated. Methods: In the middle school classrooms which were selected as the experimental subjects, IoT-based indoor air quality monitoring equipment was installed for real-time monitoring. Three types of plant models (passive, active, and active+light) were installed in each classroom to evaluate the effects on improving indoor air quality. Results: The concentration of PM in the classroom is influenced by outdoor air quality, but repeated increases and decreases in concentration were observed due to the influence of students' activities. There was a PM reduction effect by applying the green-wall model. There was a difference in PM reduction efficiency depending on the type of green-wall model, and the reduction efficiency of the active model was higher than the passive model. Conclusions: The active green-wall model can be used as an efficient method of improving indoor air quality. Additionally, more research is needed to increase the efficiency of improving indoor air quality by setting conditions that can stimulate the growth of each type of plant.

• 산업경영시스템학회지
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• 제41권4호
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• pp.101-110
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• 2018

This study aims to objectively measure the efficiency of nanotechnology R&D programs by systematically evaluating the inputs and outputs of nanotechnology R&D activities and to find implications for improving the efficiency of nanotechnology R&D programs. Data on input factors such as R&D investment, R&D manpower, R&D period, and output factors such as paper, patent, and commercialization for R&D projects which started from 2008 or afterwards and ended by 2011 are gathered through National Science and Technology Knowledge Information Service, which are used for efficiency evaluation. In this study, we analyzed R&D efficiency in detailed technology units in depth. The process taken in this study is as follows. First, the basic statistics of input and output factors to compare and analyze R&D investment, R&D manpower, R&D period, paper, patent, and commercialization status by technology unit are analyzed. Next, DEA models are utilized to derive the overall efficiency, pure technology efficiency, and scale efficiency by conducting the efficiency evaluation for each technology unit, from which implications for strategic budget allocation are derived. In addition, partial efficiency evaluation is conducted to identify advantages and disadvantages of each technology unit. In turn, cluster analysis is performed to identify similar technology units, from which implications for efficiency improvement are derived.

• 한국수소및신에너지학회논문집
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• 제20권5호
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• pp.416-423
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• 2009

High-temperature steam electrolysis (HTSE) using solid oxide cell is a challenging method for highly efficient large-scale hydrogen production as a reversible process of solid oxide fuel cell (SOFC). The overall efficiency of the HTSE hydrogen and synthesis gas production system was analyzed thermo-electrochemically. A thermo-electrochemical model for the hydrogen and synthesis gas production system with solid oxide electrolysis cell (SOEC) and very high temperature gas-cooled reactor (VHTR) was established. Sensitivity analyses with regard to the system were performed to investigate the quantitative effects of key parameters on the overall efficiency of the production system. The overall efficiency with SOEC and VHTR was expected to reach a maximum of 58% for the hydrogen production system and to 62% for synthesis gas production system by improving electrical efficiency, steam utilization rate, waste heat recovery rate, electrolysis efficiency, and thermal efficiency. Therefore, overall efficiency of the synthesis production system has higher efficiency than that of the hydrogen production system.

• The Journal of Asian Finance, Economics and Business
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• 제7권7호
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• pp.439-451
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• 2020

This study focused on researching the factors affecting retail banking efficiency of Vietcombank branches in the Mekong-Delta region. By collecting data from financial statements from 15 branches of VCB in the Mekong-Delta Region between 2015 and 2018, the paper applies DEA estimation to measure the effectiveness of retail banking activities and uses the Tobit regression model to identify factors affecting retail banking efficiency. The results demonstrate that the retail banking efficiency of branches averaged 52.5% during the period. The rating result shows the branches in An Giang, Can Tho, Dong Thap, Kien Giang, Long An, Phu Quoc and Tra Noc rank at the top technical efficiency. In group of medium efficiency, there are branches in Soc Trang, Tien Giang and Vinh Long. In the category of the poor efficiency are the branches in Bac Lieu, Ben Tre, Ca Mau, Chau Doc and Tra Vinh. The results also show that bank scale-related factors, capital adequacy, credit quality, time specific and region impact significantly the retail banking efficiency. The research not, only contributes to enriching the empirical research method but also is significant for the management activities in business developing strategies, improving the operational efficiency of Vietcombank in the region.

• 보건행정학회지
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• 제15권2호
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• pp.53-69
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• 2005

This study has two different objectives. First of all is to comparing results of size efficiency scoring on Public Corporation Medical Center(PCMC) by years of 1993, 1997 and 2003 using Data Envelopment Analysis (DEA). The second is to explore the relationship between revenue and PCMCs' efficiency score, and the relationship between expenses and the efficiency score in 2003. The average efficiency scores were significantly decreased by years of 1993, 1997 and 2003. The revenue per bed(revenue) in 2003 was smaller than the expenses per bed(expenses) in 2003, therefore PCMCs had deficits in 2003. The expenses was negatively related to the efficiency score. Therefore its means was that improving efficiency score decreased expenses. Contrarily, the revenue had any significant relation to the efficiency score. PCMC needs to various endeavors to improve their productivity and efficiency. One of the alternatives is reduce of work load through integration of PCMC and development of new performance index reflecting their situation and future direction.

• 산업경영시스템학회지
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• 제44권3호
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• pp.248-261
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• 2021

Scientific and technological performances (e.g., patents and publications) made through R&D play a pivotal role for national economic growth. National governments encourage academia-industry cooperation and thereby pursue continuous development of science technology and innovation. Increasing R&D-related investments and manpower are crucial for national industrial development, but evidence of poor performance in business performance, efficiency, and effectiveness has recently been found in Korea. This study evaluates performance efficiency of the 6T sector (Information Technology, Bio Technology, Nano Technology, Space Technology, Environment Technology, Culture Technology), which is considered a high-potential promising industry for the next generation growth and currently occupies two thirds of the national R&D projects. The study measures the relative efficiency of R&D in a comparative perspective by employing the Data Envelopment Analysis (DEA) method. The result reveals overall low efficiency in basic R&D (0.2112), applied R&D (0.2083), development R&D (0.2638), and others (0.0641), confirming that economic performance and efficiency were relatively poor compared to production efficiency. Efficient R&D needs policy makers to create strategies that can increase overall efficiency by improving productivity performance and quality while increasing economic performance.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.172-176
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• 1995

Schemes to trap weakly absorbed light into the cell have played an important role in improving the efficiency of both amorphous and crystlline silicon solar cells. One class of scheme relies on randomizing the direction of light within the cell by use of Lambertian(diffuse)surfaces. A second class of scheme relies on the use fo well defined geometrical features to control the direction of light wihin the cell, Widly used geometrical features in crystalline silicon solar cells are the square based pyramids and V-shaped grooves formed in (100) orientated surfaces by intersecting(III) crystallographic planes exposed by anisotropic etching. 18.5% conversion efficiency of Buried Contact Solar Cell with pyramidally textured surface has been achieved. 18.5% efficiency of silicon solar cell is one the highest record in the world The efficieny of cell without textured surface was 16.6%, When adapting textured surface to the Cell, the efficiency has been improved over 12%.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.586-589
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• 2004

This paper attempts to propose the decision support model, which can be employed for 22 mail centers to improve their operational efficiency and competitive. This model deals with both DEA method and system dynamics model. DEA is a management tool aimed to determine relative efficiency of independent decision making unit. We measured the relative efficiency between mail centers using CCR model and tried to find the reason for inefficiency mail centers. Also, we introduced the system dynamics model to present the strategic policy for mail center to strengthen their efficiency.