• 에너지공학
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• 제21권4호
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• pp.398-401
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• 2012

본 연구에서는 자동차용 엔진 폐열 회수 유기랭킨사이클에 적용하기 위해 개발 중인 스크롤 팽창기의 효율을 상용 스크롤 팽창기와 비교 분석을 수행하였다. 팽창기 효율 특성 시험을 위해 유기랭킨사이클을 운전하면서 팽창기 출력, 팽창기 입구 온도, 압력 및 작동유체(냉매 R134a)의 유량을 측정하였으며, 개발 중인 스크롤 팽창기의 전효율은 상용 스크롤 팽창기의 전효율에 비해 매우 낮은 수준을 나타내었다. 특히 팽창기 내부의 작동유체 누설에 의한 체적효율 저하가 전효율 저하에 큰 영향을 주는 것으로 파악되었기 때문에 향후 팽창기 효율 향상을 위해 팽창기 내부의 누설문제를 필히 해결해야할 것으로 분석되었다.

• International journal of advanced smart convergence
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• 제9권3호
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• pp.17-27
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• 2020

With the continuous development and application of Internet technology, in recent years, new technologies such as cloud computing, big data, the Internet of Things, and AI are becoming more and more familiar to the general public. The development of a digital society has entered a new period of development. In this paper, we used on the 2018 annual data of 50 listed companies with blockchain concept stocks in China. Using data envelopment analysis (DEA) to study and analyze the input-output efficiency, it can be concluded that the input-output efficiency of 50 listed companies is very different. Inefficient companies are as high as 62%. Most companies have a large room for improvement in input-output efficiency due to uneconomical scale or inefficient technology. In order to better improve the company's input-output efficiency, one must improve the efficiency of resource utilization, optimize the company's research and development costs and the input and management of technical personnel; the second is to increase technological innovation and business innovation.

• 대한산업공학회지
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• 제19권1호
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• pp.61-71
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• 1993

We focus on a way of combining the Monte Calro methods of antithetic variates and control variates to reduce the variance of the estimator of the mean response in a simulation experiment. Combined Method applies antithetic variates (partially) for driving approiate stochastic model components to reduce the vaiance of estimator and utilizes the correlations between the response and control variates. We obtain the variance of the estimator for the response analytically and compare Combined Method with control variates method. We explore the efficiency of this method in reducing the variance of the estimator through the port operations model. Combined Method shows a better performance in reducing the variance of estimator than methods of antithetic variates and control variates in the range from 6% to 8%. The marginal efficiency gain of this method is modest for the example considered. When the effective set of control variates is small, the marginal efficiency gain may increase. Though these results are from the limited experiments, Combined Method could profitably be applied to large-scale simulation models.

• Journal of Korean Society for Atmospheric Environment
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• 제16권E2호
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• pp.79-84
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• 2000

The Electrostatic Precipitator is one of the most favorable device of particulate control systems because of the relatively higher collection efficiency and easier operation/maintenance. However, it requires very high initial coat especially for discharging electrodes and collecting plates. In dealing with such problems, development of optimum design can be one of the solutions. In this study, a bench-scale electrostatic precipitator was operated in terms of collection area and corona power, and its performances were analyzed focusing on collection efficiency. A result of this study, a more advanced approach for designing cost-effective precipitator by promoting corona power at a minimized collection area was proposed.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 춘계 학술논문 발표대회
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• pp.59-60
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• 2012

A large-scale construction project relies much on the efficiency of construction equipment. Therefore, efficient and accurate measurement on the productivity of construction equipment is one of important task in the construction industry. Based on the motivation, this paper proposes a 11-axis composite sensor for an automatic measurement of construction equipment. A 11-axis composite sensor is composed of a gyroscope, geomagnetic and accelerometer sensor for the purpose of real-time motion captures of construction equipment. It is expected that the proposed system can save considerable time, effort and cost of measuring a efficiency of construction equipment.

• 설비공학논문집
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• 제27권8호
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• pp.440-447
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• 2015

In the shipbuilding process, the confined work spaces of the ship are formed continuously; the ventilation method can therefore be limited to dilution ventilation due to the complex structure and limited opening of the confined space. Also, it is difficult to evaluate air-quality using measurement and an adequate ventilation method. CFD simulation methods are typically used in analyzing ventilation efficiency in these cases. In this study, a method is suggested to analyze the air quality of the complex enclosures in shipbuilding using CFD. Especially, among the conventional indices, the ventilation efficiency scales or indices, the supply air contribution (SVE4), and the age of the air (SVE3) (fit for the confined and complex enclosure) were applied.

• 보건행정학회지
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• 제9권4호
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• pp.87-119
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• 1999

The main purpose of this research is to measure and analyze how productive the health centers are and how much inputs(or outputs) in the inefficient health centers should be decreased(or increased) for efficiency. The evaluation of the performance of health centers gives a strong incentive to improve resource allocation in regional health planning. It has been, however, implemented very rarely until now. In this regard, this paper measures the performance of the health centers with a single indicator for multiple-outputs in terms of productivity(technical efficiency), based on Data Envelopment method. The 20 Kyungnam health centers which provide clinic services and specific primary health care services were analyzed. The results show that 50.0% of 20 health centers were productive with respective to overall technical efficiency, 65.0% were productive for pure technical efficiency, and 50.0% for scale efficiency. The inefficient group includes Geoje, Mahsan, Miryang, Sahchun, Tongyoung, Gosung, Nahmhae, Euryang, Hahmahn, Hahbchun health centers. The worst case was identified as Tongyoung health center which represented a 47.5% efficiency, compared with productive health centers. The empirical results for input-output analysis indicates that the low-productive health centers have excessive manpower in administration department, producing low outputs in clinical services and vaccination program. These findings imply that a systemic evaluation of the performance of the Korean health centers and the subsequent structural reform are strongly required.

• 농업생명과학연구
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• 제45권6호
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• pp.279-289
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• 2011

이 논문에서는 부트스트래핑 DEA 모형을 이용하여 품목농협의 효율성 분석 값의 통계적 유의성을 분석하였다. 분석결과, 첫째, 일반적 DEA모형에 의한 기술효율성은 0.878로 추정된 반면, 부트스트래핑 기법을 적용하면 0.804로 추정되었다. 그러나 두 값의 차이는 신뢰구간 범위 내에 있기 때문에 통계적으로는 유의하지 않다. 또한 95% 유의수준하에서 기술효율성의 통계적 신뢰수준은 0.726에서 0.874로 분석되었다. 둘째, 일반적 DEA모형에서 효율적인 품목농협으로 추정된 19개 농협 모두 부트스트래핑 기법을 적용한 경우 비효율적인 것으로 추정되었다. 이는 일반적 DEA모형의 경우 비효율적인 품목농협이 효율적인 것으로 추정될 수 있다는 것이다.

• 한국항해항만학회지
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• 제30권4호
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• pp.267-275
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• 2006

Due to the growth of container traffic and port competition, ports have increasingly been under pressure to improve their efficiency in port operation and port management for competitive edge. The purpose of this study is to compare the technical efficiency among major container terminals in China, Korea and Singapore using Data Envelopment Analysis (DEA). This paper analyses the returns-to-scale using the output orientation of VRS and CRS model. The benefits of this study examining the relative performance of container terminals will enable container terminal operating companies or port policy makers in those countries to identify current slacks and to set up a proper port management and operation plan to improve their productivity.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1079-1084
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• 2000

The apartment houses which were constructed in a large quantity are currently being deteriorated and the reuse of them is directly related to the economic and environmental problem of the nation. Therefore, this research approaches to structural planning other than to the materials and/or the repair for the reuse of these deteriorated buildings. The research suggests the structural planning technique which includes the idea for the reinforcement of the structure in a part to improve the structural efficiency by investigating the current condition which includes the structural type of the buildings, examining the plan for the improvement of the structural efficiency, establishing the model of the space reorganization associated to the capability changes for the scale, the use, and the facilities, and checking of the structural efficiency through the structural analysis for the building structure suggested to be replaced.