• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1313-1320
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• 2011

World Business Council for Sustainable Development(WBCSD) is effort to achieve sustainable development in economic growth, environmental preservation and social development. Being this way, it is essential for developing evaluation tool which quantify to fulfill sustainable development. Eco-efficiency is one of the quantitative tools to evaluate environmental impact and economic aspect. Eco-efficiency, in general term, means creating more value of product or services with less impact to environment. It indicates as environmental impact in denominator and value of product or services in numerator. Eco-efficiency shows how much economic value reveals to unit environmental impact caused by product or service as an indicator. This study aims at developing eco-efficiency indicator of railway industry considering use stage among the entire life cycle stage of KTX and Saemaul train and also, figure out eco-efficiency value through indicator. Therethrough, it is enables to evaluate created value per environmental aspects. Since rail vehicles demands a lot of energy to transport people during use stage, the environmental impact is more significant than other lkfe cycle stages. Therefore, it quantified environmental indicator as CO2 emission and economic indicator as transportation record per a year with an annual income. This study contributes to be used as a tool for quantifying indicator of comparison evaluation in respect of rail vehicle in use stage.

• 산업공학
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• 제22권4호
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• pp.336-346
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• 2009

One of primary assumptions on DEA is that all DMUs for evaluation should be homogeneous. In comparative analysis among DMUs with relative efficiency measurement, it should be evaluated under identical conditions by ruling out external environmental influences. In this study, a measurement of innovation efficiency using the three-stage approach is performed. The approach employs DEA to measure relative efficiency and Tobit regressions to control external variables affecting innovation activity. The approach applied to firms in Korean Innovation Survey: Service Sector 2003 and 2006. Final efficiency scores of the approach represent net efficiency of the innovation. This study found that there is a increasing on technical efficiency of third stage, and it has difference with first stage significantly. Besides, a decrease on standard deviation of third stage is found. It means DMUs biased lower due to unfavorable condition and ones biased higher due to favorable condition are fallen into an identical operating environment through the approach. A measurement of net efficiency, excluding external effects, ensures the homogeneity of DMUs so that improves the reliability in terms of its analysis results. This study is expected to provide a direction and to be a valuable reference to further evaluation of innovation performance in Korean service sector.

• 대한산업공학회지
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• 제40권2호
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• pp.172-183
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• 2014

This paper measures and compares the efficiency of national health technology R&D programs focused on translational research program increasing importance using data envelopment analysis (DEA). Three input variables and three output variables are selected for DEA. Inputs are funds, researchers, and project period and outputs are SCI (E) papers, applied and granted patents, and impact factor. This study uses a three-stage approach. In the first stage, output-based DEA model is applied to evaluate the efficiency of decision making unit (DMU). In the second stage, based on efficiency scores of target diseases high-efficiency group and low-efficiency group are classified. And then strategic portfolio matrix of translational research program is composed of four dimensions combining research types. Mann-Whitney U test is then run to compare average efficiency scores among four groups. In the final stage, Tobit regression model is used to estimate factors likely to influence the efficiency. The results are expected to provide policy implications for effectively establishing investment strategy and managing performance of R&D program.

• 품질경영학회지
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• 제37권4호
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• pp.100-110
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• 2009

The customer-driven efficiency evaluation has been in the mainstream of public administration research, since the 1980s. However, there have been relatively fewer efficiency evaluation research in public administration compared to those of public institutions. This paper is to analyze the service efficiency of public sector using Data Envelopment Analysis(DEA). We suggested two stage DEA model to accomplish efficiency evaluation that an operation and performance characteristic of the public institution were reflected and then the number of the government employee and tax expenditure per residents were used as the input elements at the 1st stage and four integrated service dimensions were used as the output elements. At 2nd stage, four integrated service dimensions and citizen's satisfaction were used as the input and output elements respectively. In addition, we suggested PSEI(Public Service Efficiency Index) which showed the efficiency of the public sector using the two stages efficiency result. According to the results for '07, there were no efficient institutions among 15 DMUs and the most efficient public institution was K(0.9150). In case for '08 analysis, there was only one efficient DMU.

• 한국항공운항학회지
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• 제30권4호
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• pp.23-32
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• 2022

Prototype UAMs are shown to us in the market. When the complete product is delivered to market, the efficiency of each UAMs can be compared by default. Before the complete product is shown to us, the comparative study on efficiency of UAMs is performed under the product cost estimation. The efficiency analysis result reveals that both of Lift & Cruise type and vectored thrust type show good efficiency at the initial stage of product. At the near terms stage, five years later from initial stage end, efficiency gets some change. Vectored thrust type of UAMs show best efficiency at the near term stage of product. Because UAMs will be used in urban area, Seoul is the place where the UAMs will be used first. The flying route from Seoul City Hall to Yongsan Park, National Assembly in Yeouido, and City Airport is no more than 10 km distance. For this short distance route, efficiency will make multi-rotor type UAM be prefered to other types. For long distance route or commuting route, life & cruise type and vectored thrust type of UAMs will be prefered on account of operational efficiency.

• 반도체디스플레이기술학회지
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• 제17권4호
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• pp.51-55
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• 2018

As the OLED industry develops, display equipment is becoming larger. As a result, the stage required for display equipment is getting bigger. This enlargement led to increase in OLED production and industrial development. However, due to the large scale of the stage, other problems due to overheating and overheating caused by heavy load on the linear motor, which is mainly used in the stage, must be solved. In this study, a linear motor equipped with a cooling channel is modeled and the three - dimensional heat conduction flow analysis for this model is simulated using Fluent to analyze the cooling efficiency and cooling efficiency according to the cooling water flow rate. As a result, the cooling channel was effective and the cooling effect and efficiency were the best when the flow rate was about 5 ~ 10 L./min. In addition, the cooling effect is increased when the flow rate is increased, but the efficiency is significantly lowered when the flow rate is more than the predetermined value.

• 품질경영학회지
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• 제47권1호
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• pp.163-186
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• 2019

Purpose: The purpose of this study was to present a methodology for assessing the efficiency of supply chain quality management considering characteristics of defense industries to provide academic and policy implications for strengthening quality competitiveness of military supplies. Methods: Using the defense industry's empirical data, conduct an efficiency evaluation by utilizing a multi-stage DEA/Entropy Model for defense industries subject to the quality level survey of military goods manufacturers in 2017. Results: The results of this study are as follows; the first step of the multi-stage DEA model, Quality Management Performance Efficiency Analysis, shows that the CCR model and the BCC model are more efficient than the parent company. the second stage of the multi-stage DEA model showed that the CCR model was slightly more efficient than the parent company and the BCC model was more efficient than the parent.the overall efficiency value of the multistage DEA model, calculated by multipointing the efficiency value of the first stage by the second stage, was more efficient than the parent. Conclusion: The results of this study show that the efficiency of supply chian quality management performance and profitability in the defense industry can be analyzed for the first time using the multistage DEA/Entropy model to identify specific inefficiencies and support objective decision making.

• International Journal of Fluid Machinery and Systems
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• 제9권2호
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• pp.107-118
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• 2016

This paper focuses on the single stage and multistage performance characteristics of centrifugal mixed flow submersible borewell pump. This study reveals that the performance of single stage pump is higher than that of multistage pumps. The head, input power and efficiency of single stage pump are higher than the per stage head, per stage input power and efficiency of multistage pumps. This study is divided into three parts. In the first part, five prototype pumps were made in single stage and multistage construction and the performance tests were conducted. In the second part, numerical validation has been done for different turbulence models and grid sizes. k-Omega SST model has been selected for the performance simulation and was validated with the performance of the test pump with static pressure tappings. In the third part, single and three stage pump performance were simulated numerically and compared with experimental results. The detailed analysis of pressure and velocity distributions reveals the difference in performance of single and three stage pump, due to non-uniform flow and difference in averaged flow velocities at the subsequent impeller inlets except the 1st stage impeller inlet.

• International Journal of Fluid Machinery and Systems
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• 제3권4호
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• pp.379-385
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• 2010

We developed a high-efficiency, wide-operating-range centrifugal blower stage to meet the demand for reduced total energy-consumption in sewage treatment plants. We improved the efficiency of the two-dimensional impeller using a shape optimization tool and one-dimensional performance prediction tool. A limit of the throat deceleration ratio was set to maintain the stall-margin of the impeller. The low solidity vaned diffuser and return channel were designed using a sensitivity analysis with orthogonal arrays and three-dimensional steady flow simulations. The low solidity diffuser was designed in order to improve the performance in the low-flow-rate region. The return channel was designed so that the total pressure loss in the return channel was minimized. Model tests of both the conventional and optimized blower stages were carried out, and the efficiency and operating range of both stages were compared. The optimized blower stage improved in stage efficiency by 3% and in operating range by 5% compared with the conventional blower stage.

• 한국산업융합학회 논문집
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• 제23권3호
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• pp.433-444
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• 2020

This study proposes a method to improve the sleep stage and efficiency estimation of sleep apnea patients using a UWB (Ultra-Wideband) radar. Motion and respiration extracted from the radar signal were used. Respiratory signal disturbances by motion artifacts and irregular respiration patterns of sleep apnea patients are compensated for in the preprocessing stage. Preprocessing calculates the standard deviation of the respiration signal for a shift window of 15 seconds to estimate thresholds for compensation and applies it to the breathing signal. The method for estimating the sleep stage is based on the difference in amplitude of two kinds of smoothed respirations signals. In smoothing, the window size is set to 10 seconds and 34 seconds, respectively. The estimated feature was processed by the k-nearest neighbor classifier and the feature filtering model to discriminate between the sleep periods of the rapid eye movement (REM) and non-rapid eye movement (NREM). The feature filtering model reflects the characteristics of the REM sleep that occur continuously and the characteristics that mainly occur in the latter part of this stage. The sleep efficiency is estimated by using the sleep onset time and motion events. Sleep onset time uses estimated features from the gradient changes of the breathing signal. A motion event was applied based on the estimated energy change in the UWB signal. Sleep efficiency and sleep stage accuracy were assessed with polysomnography. The average sleep efficiency and sleep stage accuracy were estimated respectively to be about 96.3% and 88.8% in 18 sleep apnea subjects.