• 대한화학회지
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• 제55권5호
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• pp.824-829
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• 2011

In Fischer-Tropsch Synthesis, because of few reactants ($H_2$, CO), scarce operating parameters affected on efficiency especially the selectivity of products. In this research, effect of operating parameters on the selectivity of Co-Mn-$TiO_2$ Fischer-Tropsch synthesis catalyst were studied by design of experimental procedure and Taguchi method. According to this research, interactions between operating factors have a crucial effect on light products selectivity. Among these interactions, (temperature${\times}$feed ratio) has the main influence on light hydrocarbons selectivity. It was concluded that temperature and feed ratio ($H_2$/CO) were the most integral operating parameters for much greater selectivity of light hydrocarbons.

• 전기학회논문지
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• 제58권4호
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• pp.694-699
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• 2009

Combined cycle plants which feature distinct advantages for power generation such as fast response, high efficiency, environmental friendliness, fuel flexiblity represent the majority of new generating plant installations across the globe. Combined cycle plants have different operating modes where the operating parameters can differ greatly depending which mode is operating at the time. This paper addresses the bidding strategy model of combined cycle plants in a competitive electricity market by using a characteristic of multiple operating modes of combined cycle plants. Simulation results of case studies show that an operating mode among multiple ones is selected strategically in generation bidding for more profit of generation company.

• Advances in Energy Research
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• 제4권3호
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• pp.239-253
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• 2016

Air quality in hospitals has always concerned hospitals' health officials due to its dangerous particles and gases. Because of the importance of air conditioning in the operating room, a system must be embedded in operating rooms to direct the contaminated air outside, and inject fresh filtered air from outside back into the room. In this study, laminar flow air conditioning system is implemented in the operating room by slot linear diffusers and with the help of air curtain. For this, stimulation Computational Fluid Dynamic (CFD) was used due to its efficiency. The aim of the present study was to find a proper solution to overcome the unfavorable factors, namely, contamination, humidity, and also temperature, velocity and pressure inside the room. These factors were implemented with different values and then stimulated through FLUENT software program. Results showed that the aforementioned factors can be overcome using air curtain and slot linear diffusers.

• 디지털융복합연구
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• 제15권10호
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• pp.31-43
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• 2017

본 연구는 DEA의 CCR/BCC 모형과 Malmquist 생산성 지수를 이용하여 택배 서브터미널 위수탁 대리점의 운영효율성을 분석했다. 투입변수로는 종업원수, 장비수, 영업비용을 선정하였으며 산출변수는 매출액을 선정하여 2014년부터 2016년 기간의 효율성을 분석하였다. 연구결과 CCR 모형과 BCC모형 모두 2014년 대비 2016년 효율성이 좋아졌으며 벤치마킹 분석결과 2016년 기준 DMU1과 DMU7이 가장 효율성이 좋은 것으로 나타났다. 또한 BCC 모형 기준 비효율성 분석결과 2014년 기준 2016년 모든 요소별 효율성이 증가한 것으로 나타났다. Malmquist 분석결과 MPI지수는 기술변화에 영향을 받아 소폭 하락하였으며 모든 DMU에서 기술퇴보가 이루어지고 있는 것으로 나타났다. 본 연구는 택배에 대한 인식을 제고하고 그동안 논문에서 다루지 않았던 서브터미널 위수탁 대리점의 실제 운영효율성을 분석하였으며 그 결과 위수탁 대리점에 대한 정부의 제도개선 및 지원정책이 필요함을 시사점으로 제시하였다. 본 연구는 파주, 김포의 신도시 택배대리점을 기준으로 분석을 수행하였다. 따라서 향후 분석범위를 타도시 및 구도심으로 넓혀 신도시와의 비교를 통한 효율성분석을 수행해야 한다.

• 한국항해항만학회지
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• 제44권2호
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• pp.119-127
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• 2020

In this study, the current state of management efficiency of ocean carriers in Korea and the factors affecting them were analyzed. The purpose of this research is to enhance global competitiveness of ocean carriers by presenting suggestions that can improve management efficiency based on the analysis results. The measurement of management efficiency was made using the DEA model. The results of testing the adequacy of the input and output variables used are as follows. Appropriate inputs are total assets, cost of goods sold, charter expenses, sales and general management expenses, and interest expenses. Appropriate variables are sales, operating income, and operating cash flow. According to the analysis results of the DEA model by these variables, inefficient carriers (78%) are nearly four times more than efficient carriers(22%). However, container carriers have the most improved management efficiency compared to 2016 and 2017. According to the panel regression analysis, the charter rate has the greatest negative impact on efficiency (CRS), and the debt rate has a significant negative impact. Thus, it appears that reducing the charter size and the debt-to-sale rate facilitate improvement of the management efficiency of ocean carriers. Additionally, the pre-sales tax return rate, value added rate, total asset turnover rate, and the scale variable and interest coverage rate have a positive (+) effect. Thus ocean carriers should restore their global competitiveness by improving management efficiency by securing stable cargoes increasing sales profitability from the cost management perspective, increasing productivity, and enhancing the efficiency of their total assets through efficient fleet management.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.24-31
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• 2000

This paper evaluates the efficiency of Korea National Railroad on the basis of revenues from 1980 to 1999. There was a significant inefficiency in this organization due to operating at an decreasing return to scale area. Although Korean Railroad in 1990s has made a great effort, his performance is still low. Consequently, it is important to insure substantiality of operations than to expand business area in order to finally improve the efficiency, in particular the revenue efficiency, of the Korea Railroad.

• 한국광학회:학술대회논문집
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• 한국광학회 2004년도 하계학술발표회
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• pp.172-173
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• 2004

Recently there has been many understood the basis device physics OLEDs and their basic operating principle. We demonstrate that there have many relation in order to improve luminescence efficiency both emitting light material physics characteristics and luminary. Efficient Electro Luminescence from organic materials was first reported in 1987 at Kodak. OLEDs emitting light material use tris-(8-hydroxyquinoline)(Alq3). Sudied maximum luminescence efficiency about structure of optimized emitting light layer of OLED which do observing change of luminescence efficiency by structure change of organic material in this paper.

• 수산해양기술연구
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• 제13권2호
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• pp.15-20
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• 1977

Fishing efficiency of conventional bamboo traps and other traps for eel Conger myriaster, was investigated. The results are as follows: ). The best fishing efficiency was observed when the trap is inclined to the sea bottom with 20 ~ 30 degrees. 2. Plastic traps were better compared with bamboo traps in rigidity and fishing efficiency. 3. Using clips in attaching branch line to main line, the operating time was saved somewhat considerably.

• International Journal of Contents
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• 제2권3호
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• pp.6-10
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• 2006

Small molecule OLED devices were fabricated and the electro-optical characteristics were analyzed. The luminance and color coordinate of the fabricated OLED device were $24,390cd/m^2$ and (x=0.15, y=0.22), respectively. Current efficiency of 6.8 cd/A and power efficiency of 2.4 lm/W were also obtained under DC operating condition. Transient light intensity was also measured by using Si photodiode.

• 전기학회논문지
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• 제62권9호
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• pp.1223-1227
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• 2013

If the factory test efficiency and field operation efficiency of water turbine are different from each other, issues for efficiency warranty can be raised. So, This paper shows the result for comparative analysis of field operating efficiency vs plant testing efficiency of the water turbine generator installed in agricultural reservoir. The efficiency of the induction generator is analyzed by the change of rotational speed with the parameter obtained by test, the efficiency of water turbine is calculated by the change of head with the design flow. Efficiency deviation of induction generator is lower but the variation of developed power is pretty high near the rated speed and the efficiency variation of water turbine is high by the fluctuation of head for constant flow. It was found that factory test efficiency and total efficiency of water turbine generator calculated according to the rotational speed are very close.