• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.99-104
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• 2020

In this paper, efficiency and loss characteristics of GaN FET were reported by applying it into the QR flyback converter. In particular, for the comparison of efficiency characteristics, QR flyback converter experimental circuits with Si FET and with GaN FET were separately produced in 12W class. As a result of the experiment, the experimental circuit of the QR flyback converter using GaN FET reached a high efficiency of 90% or more when the load power was 2W or more, and the maximum efficiency was observed to be about 92%, and the maximum loss power was about 1.1W. Meanwhile, the efficiency of the experimental circuit with Si FET increased as the input voltage increased, and the maximum efficiency was observed to be about 82% when the load power was 9W or higher, and the maximum loss power was about 2.8W. From the results, it is estimated that that in the case of the experimental circuit applying the GaN FET switch, the power conversion efficiency was improved as the switching loss and conduction loss due to on-resistance were reduced, and the internal loss due to the synchronous rectifier was minimized. Consequently, it is concluded that the GaN FET is suitable for under 20W class power supply unit as a high efficiency power switch.

• Journal of Hydrogen and New Energy
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• v.13 no.4
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• pp.304-312
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• 2002

In this study, the performance of the $5Nm^3/hr$ compact type steam reformer which was developed for application of fuel cell or hydrogen station was evaluated in terms of gas process efficiency. For these purposes, reforming efficiency and total efficiency with system load change were analyzed. The reforming efficiency was calculated from the total molar flow of hydrogen output over total fuel flow input to the reformer and the burner on the higher heating value(HHV). In the case of the total efficiency, recovered heat at the heat recovery exchanger was considered. From the results, it was known that system performance was stable, because methane conversion showed the a slight decline which is about 2% though increasing system load to full. Reforming efficiency was increased from 20% to 58%, respectively as increasing system load from 10% to 90%. It was found that total efficiency was higher then reforming efficiency because of terms of heat recovered. As a results, it was known that total efficiency was increased form 75% to 83% at the 10% and 90% system load, respectively. From these results, it is concluded that compact steam reformer which is composed of stacking plate-type reactors is suitable to on-site hydrogen generator or to fuel cell application because of quick start within 1 hr and good performance.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.855-863
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• 2019

The efficiency of fishway installed in rivers can be directly evaluated by means of fish monitoring. On the other hand, when it is difficult to monitor the fish in certain conditions, or when planning a fishway, the efficiency can be evaluated indirectly through the hydraulic analysis. In this study, the hydraulic analysis technique for evaluating the efficiency of a fishway was presented. The River-2D model with the fish physical habitat module was used for the analysis of the attraction efficiency, and the weighted usable area was proposed as an index of the efficiency. In the analysis of passage efficiency, the three-dimensional model, Flow-3D, was used as an evaluation tool to describe the fluid behavior on a hydraulic structure with free surface. The ice-harbor type fishway at Baekgok weir in the Deokcheon River was selected as a test-site, and the efficiency was estimated using the hydraulic analysis. And then it was compared with fish monitoring data acquired from the river. As a result, it is difficult to replace the hydraulic analysis results with the efficiency quantitatively, but it can help to grasp the general tendency.

• Journal of the Korea Society of Computer and Information
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• v.22 no.2
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• pp.119-125
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• 2017

In this paper, we propose an approach to evaluating the performance of the national R&D investment in IT(Information Technology) areas in terms of paper, patent and commercialization, and seeking ways to improve the efficiency of the national R&D investment. This is because the government has focused the national R&D investment on IT areas for some time. For that purpose, we gather data on investments, papers, patents, and commercializations for the government sponsored R&D projects in IT areas through National Science & Technology Information Service. From which, we summarize the investment and performance in terms of papers, patents, and commercializations for each IT area, evaluate efficiency per R&D investment for each IT area, and compare the efficiencies among IT areas. Finally, we drive implications for efficiency enhancement and strategic R&D budget allocation for each IT area.

• Proceedings of the KSR Conference
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• 2011.05a
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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.

• Journal of Digital Convergence
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• v.14 no.5
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• pp.165-176
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• 2016

The purpose of this study is to examine the effects of the IT resources on the work efficiency and corporate performance in Mobile Smart-Work Environment with IT convergence Technology by applying the Resource-Based View. The study has an academic meaning by empirically analyzing the effects of factors identified based on the existing study on the IT resources in Mobile Smart-Work, and practical implications to identify how the significance of the Mobile Smart-Work used as a platform of variety industries in manufacturing, logistics, service, distribution, finance, public institutions, and so on positively affects improvement of corporate efficiency and performance. The results showed that IT Infrastructure and IT skills in the Mobile Smart-work environment were found to bring positive effects on individual work efficiency, and IT skills had positive influence on team work efficiency. Also, we confirmed the individual and team work efficiency positively affect financial and market performance of business firms. Finally, we expect that business firm equipped with IT resources in the Mobile Smart-Work environment with IT convergence Technology. It can improve this work efficiency and the performance, which leads to strengthening the core competency.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.4
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• pp.27-33
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• 2001

In this study, it is observed that the distribution of combustion chamber volume affects the volumetric efficiency. The distribution ratio was adjusted by controlling combustion chamber volume of head and piston bowl one. Four cases were investigated, which are the combination of different distribution ratios and different compression ratios (9.8-10.0). A commercial SOHC 3-valve engine was modified by cutting the bottom face of the head and/or replacing the piston by the one that has different volume. The result shows that the less the head side volume, the more volumetric efficiency is achieved under the same compression ratio. It is also observed that increasing volumetric efficiency results in early knock occurrence due to increased "real" compression ratio. To consider reliability in estimating the volumetric efficiency, we examined the sensitivity of the AFR equation to possible errors in emission measurements. It is shown that the volumetric efficiency, which is calculated by measuring AFR and fuel consumption, can be controlled in 1% error. 1% error.

• Journal of Distribution Science
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• v.14 no.5
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• pp.107-114
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• 2016

Purpose - Loading can decrease the productivity due to the possibility of carrying out with the opposite order of storage in container terminal. When the container is to be taken out, it is needed to move the container stacked upon the container to be carried out to other place temporarily. It is called as rehandling. Remarshalling, with the loading plan, is the arranging the containers before the ship arrives in order to avoid the rehandling during the carrying out. The present study tried to find out the factors affecting the efficiency when building the remarshalling plan with the utilization of neighboring storage space as a outer slot, and analyzed the efficiency of several remarshalling algorithms with the combination of those factors. Research design, data and methodology - The present study used, when the remarshalling plan is prepared for utilizing the outer slot, the simulation methods in order to compare the efficiency of the remarshalling algorithms which made with the factors affecting the efficiency. The factors affecting the efficiency are the method of making the child node, method of arrangement, and possibility of application of FIX. In order to analyze the affecting factors on the efficiency, several algorithms are prepared with the combination of production of the child node and the arrangement method with the availability of FIX application. With this algorithm, the effect of the factors on the efficiency after building up of remarshalling plan with the target on the bay with 10 rows, 8 columns, and 10 indices. Results - The method of rearrangement and making of a child node as the factor affecting the efficiency of remarshalling utilization of the outer bay were studied. It is efficient to combine the method of making a child node with MCS in order to reduce the number of moving the containers. For reducing the time in carrying out, it was found that all arrangement methods should be combined with RCS for the efficiency. The result of experiment shows the application of FIX with good result in case of succession ratio. In addition, when FIX was not applied, all of the most combinations resulted in short time in remarshalling. As a result, it can be concluded that the algorithm with proper combination of making the child node and the arrangement can increase the job efficiency based on the importance. Conclusion - The present study suggested and analyzed the algorithms with the combination of the arrangement method, the making of child node, and FIX. It is needed to develop the algorithm to judge the possibility whether the best remarshalling plan can be built or not within the bay in order to find a better method between the two cases such as within the bay and outer the bay. As a method for extending the study on the factors affecting the efficiency, it is possible to find out the way to build the remarshalling plan within the permitted time under any storage situation.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.3
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• pp.87-94
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• 2020

In this study, the factors affecting the efficiency of 48 projects of private R&D institutes were analyzed using the Tobit model. Influencing factors were selected as open R&D network size, IT industry, interaction between R&D network size and IT industry, and type of R&D network cooperation. As a result of Tobit analysis, the R&D network size, the IT industry, and the type of R&D network cooperation were found to be significant. The larger the open R&D network size, the lower the efficiency, and the IT industry showed lower R&D efficiency than other industries. In addition, cooperation with universities and research institutes showed lower R&D efficiency than cooperation with companies. As a result of these studies, companies will be able to select and focus on cooperation with the outside in relations and investment allocation.

• Journal of Information Technology Services
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• v.5 no.1
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• pp.1-16
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• 2006

This paper analyzes the technical efficiencies of 40 Korean system integration firms using data envelopment analysis (DEA) and Malmquist productivity indices. Technical efficiencies on average had been decreased over the five year period and the efficiency difference between best practice firms and catch-up firms had been increased during this period, meaning that the industry structure has become matured and the possibilities for catch-up firms to be efficient are not remained so much. The differences in efficiency by the differences in ownership structures are statistically significant. It implies that the efficiencies of group-affiliated firms have come from benefits such as the captive market umbrellas, not from their own management competencies. In addition, the technical efficiency is highly correlated with captive market sales, information productivity, sales per employees, rates of value added, returns on invested capital, and EBITDA.