• Proceedings of the Society of Korea Industrial and System Engineering Conference
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• 2002.05a
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• pp.189-194
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• 2002

As a environment of SCM is issued recently, many enterprises are concerned about inventory control for an efficiency of operation and reliablity. The goal of them is to match up to improving of facilities and redoing of inventory cost. To put an efficiency in the operation rate of facilites, A moderate provision of spare parts for that would come into a matter. This study designs two-echelon spare parts distribution system and sees over the relationship between operating rate and inventories of spare parts. and then it determines fitting inventories and investment cost considering an operating rate.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.507-510
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• 2008

Characteristics of an autothermal reformer at various operating parameters have been studied in this paper. Numerical method has been used, and simulation model has been developed for the analysis. Full Combustion reaction, Steam Reforming(SR) reaction, Water-Gas Shift(WGS) reaction, and Direct Steam Reforming(DSR) reaction are assumed as dominant chemical reactions in the autothermal reformer. Simulation results are compared with experimental results for code validation. Operating parameters of the autothermal reformer are inlet temperature, Oxygen to Carbon Ratio(OCR), Steam to Carbon Ratio(SCR), and Gas Hourly Space Veolcity(GHSV). SR reaction rate decreases with low inlet temperature. If OCR is increased, $H_2$ yield is increased but optimal point is suggested. WGS reaction is activated with high SCR. When GHSV is increased, reforming efficiency is increased but pressure drop may decrease the system efficiency.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.129-138
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• 1999

In this paper, our main issue is that establishing the control procedure of continuous gas flow rate according to combustion fan RPM. For this, first, we decide the optimum operating condition of gas swirl burner through analysis of combustion characteristics - thermal efficiency, combustion efficiency and exhaust gases such as CO, $CO_{2}$, $O_{2}$, $NO_{x}$ and THC. Second, fuel gas flow rate of gas valve is decided with considering excess air ratio and combustion fan RPM is decided by the target of combustion air flow rate. Finally, experimental operating equation is acquired by regression for gas valve and combustion fan. This equation is the control equation of continuous gas flow rate and always gas flow rate is decided by combustion fan operating RPM.

• The KSFM Journal of Fluid Machinery
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• v.14 no.2
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• pp.11-16
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• 2011

This paper presents a numerical study of casing treatments on a centrifugal compressor stage to improve stability and the surge margin. High efficiency, a high pressure ratio, and a wide operating range are required for a high performance centrifugal compressor. In the present study, a ring groove arrangement was applied to the transonic centrifugal compressor. According to the numerical analysis using a commercial code ANSYS-CFX, the unstable phenomena limiting the range of the centrifugal compressors were compared with and without a ring groove. Although the ring groove decreased the efficiency, but increased the operating range by suppressing a flow separation at the leading-edge of the impeller especially near shroud part. Newly designed ring groove arrangement improved the compressor performance and increased the operating range of the compressor.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.157-164
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• 2012

PURPOSES: Regional offices of the Ministry of Land, Transport and Maritime Affairs use a computerized system called KAMIS so as to manage road equipment systematically. Road agencies can record number of operating days by equipment, actual working hours, accumulated operating hours (or distance) by equipment, and operating cost. However, KAMIS does not provide critical information, although it is strongly related to efficient road management equipment operation. In other words, road agencies do not know whether they have sufficient equipment to handle their actual work. METHODS: Therefore, this study suggests a methodology to evaluate for operational efficiency of road management equipment using analytical hierarchy process(AHP). First of all, estimated weights related criteria can be produced by AHP, and then use operational history by pieces of equipment. RESULTS: Results show that importance of management work can differ from weather conditions through five areas. CONCLUSIONS: Commonly, this results can imply to help save money for the purchase and maintenance of road management equipment, and they would improve the functional performance of KAMIS.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1817-1818
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• 2008

Even though efficiency of coal-fired power plant is proportional to operating temperature, increasement of operating temperature is limited by a technological level of each power plant components. It is an alternative plan to increase operating pressure up to ultra super critical point for efficiency enhancement. It is difficult to control in that pressure within safety guideline that many unexpected phenomena are happen because that region is highly nonlinear region. In this paper, Advanced process control algorithm, ARX and Fuzzifier, is introduced. Then power plant control logics applied Unit Step Optimizer, which is combination of ARX and Fuzzifier are proposed. Its performance is tested and analyzed with design guide line.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.67-68
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• 2015

This paper describes humanoid eye drive system. The eye drive system has been developed by using more than two motors for operating 2 degree-of-freedom. It needs to accomplish purpose for operating the robot eye like movement of the human eye. However it makes problems that it increases energy consumption and requires relatively large space of operating system. Thus it needs technology to minimize and have high efficiency. This paper introduces the adequacy of perviously eye drive system. And it shows research value of the spherical motor system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2285-2290
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• 2008

Even though efficiency of coal-fired power plant is proportional to operating temperature, increasement of operating temperature is limited by a technological level of each power plant component. It is an alternative plan to increase operating pressure up to ultra super critical point for efficiency enhancement. It is difficult to control process of power plant in ultra super critical point because that point has highly nonlinear characteristics. In this paper, new control logic, Unit Response Optimizer Controller(URO Controller) which is based on Fuzzy logic and Model Predictive Controller, is introduced for better performance. Then its performance is tested and analyzed with design guideline.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.645-651
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• 2020

In this study, It is necessary that we should study on more effective use about reciprocating engines because there are huge increase of air pollution. Diesel Engine is operated by injecting fuel directly to combustion chamber with high pressure. Diesel Engine has greater thermal efficiency and durability than Gasoline Engine. Also, Diesel Engine emitted low harmful exhaust witch caused by Gasoline Engine. There are many ways to improve of performance and decrease of harmful exhaust by controlling injection timing, changing amount of fuel and engine speed and so on. Especially, development and application of common rail direct injection Engine cause the increase of thermal efficiency by controlling a various of operating conditions. In this study we analyze characteristics of performance by changing a various of operating conditions.

• Progress in Superconductivity and Cryogenics
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• v.15 no.3
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• pp.35-39
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• 2013

In this paper, we present test results of developed 100 W class linear compressor for Stirling-type pulse tube refrigerator. The fabricated linear compressor has dual-opposed configuration, free piston and moving magnet type linear motor. Power transfer, efficiency and required pressure waveform are predicted with designed and measured specifications. In experiments, room temperature test with flow impedance is conducted to evaluate performance of developed linear compressor. Flow impedance is loaded to compressor with metering valve for flow resistance, inertance tube for flow inertance and buffer volumes for flow compliance. Several operating parameters such as input voltage, current, piston displacement and pressure wave are measured for various operating frequency and fixed input current level. Behaviors of dynamics and performance of linear compressor as varying flow impedance are discussed with measured experimental results. The developed linear compressor shows 124 W of input power, 86 % of motor efficiency and 60 % of compressor efficiency at its resonant operating condition.