• Journal of the Korean Society of Combustion
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• v.10 no.1
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• pp.20-26
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• 2005

In the present study, catalytic combustion of hydrogen-air premixture in a millimeter scale monolith coated with Pt catalyst was investigated. As the combustor size decreases, the heat loss increases in proportion with the inverse of the scale of combustion chamber and combustion efficiency decreases in a conventional type of combustor. Combustion reaction assisted by catalyst can reduce the heat loss by decreasing the reaction temperature at which catalytic conversion takes place. Another advantage of catalytic combustion is that ignition is not required. Platinum was coated by incipient wetness method on a millimeter scale monolith with cell size of $1{\times}1mm$. Using this monolith as the core of the reaction chamber, temperatures were recorded at various locations along the flow direction. Burnt gas was passed to a gas chromatography system to measure the hydrogen content after the reaction. The measurements were made at various volume flow rate of the fuel-air premixture. The gas chromatography results showed the reaction was complete at all the test conditions and the reacting species penetrated the laminar boundary layer at the honeycomb and made contact with the catalyst coated surface. At all the measuring locations, the record showed monotonous increase of temperature during the measurement duration. And the temperature profile showed that the peak temperature is reached at the point nearest to the gas inlet and decreasing temperature along the flow direction.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.830_831
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• 2009

Wind power system attracts most interest because of high-energy efficiency with environment-friendly. Small scale wind power applications requires a cost effective and mechanically simple generator in order to be a reliable energy source. The use of direct driven generators, instead of geared machines, reduces the number of drive components, which offers the opportunity to reduce costs and increases system reliability and efficiency. This paper presents the development of a coreless axial-flux permanent magnet(AFPM) generator for a urban wind power system. It is analyzed by electromagnetic simulation program Maxwell 3D

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1280-1285
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• 2004

Microsystem technology has been applied to space technology and became one of the enabling technology by which low cost and high efficiency are achievable. Micro propulsion system is a key technology in the miniature satellite because micro satellite requires very small and precise thrust force for maneuvering and attitude control. In this paper research on micro solid propellant thruster is reported. Micro solid propellant thruster has four basic components; micro combustion chamber, micro nozzle, solid propellant and micro igniter. In this research igniter, solid propellant and combustion chamber are focused. Micro igniter was fabricated through typical micromachining and evaluated. The characteristic of solid propellant was investigated to observe burning characteristic and to obtain burning velocity. Change of thrust force and the amount of energy loss following scale down at micro combustion chamber were estimated by numerical simulation based on empirical data and through the calculation normalized specific impulses were compared to figure out the efficiency of combustion chamber.

• Journal of Korea Port Economic Association
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• v.26 no.4
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• pp.219-246
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• 2010

Countries around the world are propelling policies and strategies to strengthen the competitiveness of their own ports as they recognize the roles and importance of the ports in the international trade and logistics. The main objective of this study is to compare efficiencies of major container ports and analyze the factors that affect the efficiencies in the three regions of East Asia, Europe, and North America, which cover most of world container shipping. We employ DEA models in analyzing the efficiencies of 45 container ports using 5 input and 2 output variables. We also carry out regression analyses to estimate the impacts of each factor on the throughput (TEU), overall technical efficiency (OTE), pure technical efficiency (PTE), and scale efficiency (SE). The analysis results show that East Asian ports, despite being smaller in average size, make greater output and achieve higher technical and scale efficiencies than European or North American ports.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.3
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• pp.415-419
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• 2016

As the need for clean coal technology has grown, so has the global research and development efforts into integrated gasification combined cycle (IGCC) plants. An IGCC plant couples a gas turbine to a gasification block. Various technical and economic problems exist in designing such a system. One such problem is the difficulty in realizing economies of scale because the single-train flow capacity of commercial IGCC synthetic gas turbine plants is limited; the capacity does not exceed a net power rating of 300 MW. To address this problem, this study modeled and simulated a synthetic gas turbine with the goal of evaluating the feasibility of a 500 MW or larger IGCC plant. First, a gas turbine with the best output and efficiency was chosen for use with natural gas. The turbine was modeled using GateCycle (a simulation tool), and the integrity of the model validated by comparing the result to the design value. Next, off-design modeling was carried out for a gas turbine with synthetic gas based on its on-design model, and the result was compared with the study result of the gas turbine manufacturer. The simulation confirmed that it is possible to create a large capacity IGCC plant by undertaking the remodeling of a gas turbine designed to use natural gas into one suitable for synthetic gas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.517-524
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• 2020

In line with the recent wave of the 4th Industrial Revolution, the environment for defense R&D is transforming into a center of high-tech military technology. In particular, developed countries are strengthening control of technology exports and technology transfer to protect advanced defense science and technology. For this reason, the budget demand for securing the ability to develop independently high-tech weapons and core technologies suitable for the future battlefield environment is increasing, and increasing efficiency in R&D investment has been highlighted for efficient distribution of limited budgets. This study examined the efficiency of the defense basic R&D project using the non-parametric approach, DEA. The R&D budget, R&D researcher, and R&D period were selected as the input variables, and the number of papers and patents were used as output variables. The efficiency of basic R&D projects was analyzed through CCR, BCC models, and SE. Lastly, based on the efficiency measurements, the cause of the inefficiency of R&D projects was suggested, and ways to improve efficiency were suggested. This study is expected to be used as useful information that can be applied to project performance management through efficiency analysis of basic defense R&D projects and be reflected in the project planning stage through feedback.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.145-148
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• 2008

A 50 Newton monopropellant thruster being developed for attitude control in a variety of aerospace application systems is described in this paper. A scaled down thruster with platinum on aluminum oxide in the reaction chamber was tested to determine the catalyst capacity. A scaled up thruster, was designed and fabricated using data obtained on small scale device, was evaluated by decomposition efficiency based on temperature, efficiency of characteristic velocity, and measurement of thrust. The performance of a scaled up thruster was 42 Newton in thrust, 98 % in efficiency of characteristic velocity, and 123 sec in specific impulse at sea level.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.3
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• pp.24-33
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• 2008

A 50 Newton monopropellant thruster being developed for attitude control in a variety of aerospace application systems is described in this paper. A scaled down thruster with platinum on aluminum oxide in the reaction chamber was tested to determine the catalyst capacity. A scaled up thruster which was designed and fabricated using data obtained from a small scale device was evaluated by its decomposition efficiency based on the temperature, the efficiency of characteristic velocity, and the measurement of thrust. The performance of a scaled up thruster was marked by a measured thrust of 42 Newton, 98 % efficiency of the characteristic velocity, a specific impulse of 123 sec at sea level.

• Journal of Digital Convergence
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• v.17 no.7
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• pp.27-34
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• 2019

The IT industry has made rapid development and also had an economic impact on other industries Also, since the fourth industrial revolution has begun in recent years ago, so The convergence between IT and other industries is increasing. Therefore, the development of the IT industry will enhance the international competitiveness It will also have a major impact on the nation's economic growth. Therefore, IT firms should be more efficient in their production. so This paper analyzes the efficiency of High-growth IT firms using DEA model. We evaluate the CCR, BBC efficiency and RTS(return to scale) of 12 IT firms. As a result, there were 6 companies with BCC efficiency 1 and 4 companies with 1 CCR efficiency. The scale of profitability was analyzed by IRS as 7 companies and CRS as 5 companies. We also suggest the IT firms which can be benchmarked based on analyzed information. It is expected to provide investors and external stakeholders with very useful information on managerial management efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.2129-2137
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• 2010

In this research, we analyze the efficiency of 20 public health centers of Gyeongnam Province, so the reduction and weakness of input and output factor were found. We used the CCR, BCC model of Data Envelopment Analysis as a method of evaluation, made a choice human resource as the input variable, made a selection the performance of health care center, ward as the output variable. The results show that 12(60%) public health centers in 20 were productive with respective to overall Technical Efficiency(average score 0.868), 14(70%) with respective to overall Pure Technical Efficiency(average score 0.924) and 12(60%) with respective to overall Scale Efficiency(average score 0.933). It is expected that this research can provide a good data for effective management of public health centers.