• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.601-604
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• 2004

Precise position and attitude control of pico-satellite requires huge number of impulses of the order of 10$^{-6}$ Ns. MEMS solid rocket array is a promising propulsion system but the higher degree of miniaturization causes unreliable operation mainly due to quenching. In order to breakthrough this situation, a novel design of solid micro-rocket is proposed, which generates tiny impulses repetitively from a single rocket not from array. This unique micro-rocket is based on the utilization of quenching, which causes propellant reaction to sustain only in a small area. A test chip of a micro solid propellant tank and micro heater array is fabricated and ignition test is conducted. Obtained results show the feasibility of this concept and future direction of this quenching-based propulsion is discussed.

• Nuclear Engineering and Technology
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• v.38 no.8
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• pp.779-784
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• 2006

The design, manufacturing process, and first operating test of a high power RF source for a proton accelerator are described. A klystron amplifier system has been developed for operation at 700 MHz, 1 MW and is composed of a triode type electron gun, six cavities, an RF output window, a beam collector, and an electromagnet. The prototype klystron was constructed and tested at a reduced duty to produce the designed output RF power.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1214-1221
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• 2006

In this paper, development and performance characteristic of propulsion system(Converter/Inverter) using IPM(Intelligent Power Module) for 120km/h AC electric vehicle is proposed. The proposed propulsion system is comprised of IPM converter and inverter stack which uses natural air-cooling system, DC-Link, OVCRf unit and control unit. And also 2-Parallel operation of two PWM converter is adopted for increasing capacity of system and the VVVF inverter control is used a mixed control algorithm, where the vector control strategy at low speed region and slip-frequency control strategy at high speed region. The proposed propulsion system is verified by main line test results as well as combined test results.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.606-615
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• 2006

This study identifies the comparison of Technical specification and Characteristics of DC Protection Relay(ETCPU200) used in DC Distribution System in Korea. ETCPU200 has completed Field Test and approved its capability by finding out causes of recent operations through lately developed digital DC protection relay in parallel operation at Maebong-Substation, Nakseongdae-Substation, Euljirosaga-Substation, Jegi-Substation and Chongryangri T/P area. It also examines additional features for efficient System Analysis and Operations.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.18-24
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• 2003

Vehicle emission is one of the major sources of air pollution, and provides some undesirable effects on the atmospheric environment and human health. In this study, the driving data were recorded during road tests in Seoul metropolitan wet and analyzed by statistical techniques. The objective of the study is to analyze the driving Patterns of passenger car that influence on emissions in urban driving. The results show that the average speed is around 29.2 km/h, and the average fuel economy is 10.23 km/$\ell$. The vehicle speed of Seoul metropolitan area is slower, and the stop-and-go operation is more frequent than CVS-75 test mode which is used far emission and fuel economy test.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.92-98
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• 2008

The flame image observation and analysis has been investigated for combustion monitoring and management of the pulverized coal firing for thermal power plant, especially for lower nitrogen oxide generation and safer operation. We aimed at obtaining the relationship between burner flame image information and emissions of nitrogen oxide and unburned carbon in furnace utilizing the flame image processing methods, by which we quantitatively determine the conditions of combustion on the individual homers. Its feasibility test was undertaken with Samchonpo thermal power plant #4 unit which has 24 burners, through which the system was observed to be effective for evaluating the combustion conditions and continuous monitoring to prevent future loss of ignition.

• Journal of Korean Vacuum Science & Technology
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• v.7 no.2
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• pp.27-32
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• 2003

A large cryo-pumping system composed of 4 cryosorption pumps was designed and manufactured to satisfy the pressure requirements of the NBI test stand. The cryosorption pump consists of a thermal shield/baffle assembly and a cryopanel coated with activated carbon granules. The thermal shield is cooled by liquid nitrogen, and the cryopanel by a commercial helium refrigerator. The operation characteristics and vacuum performance of the cryosorption pump were investigated. The cooling down time of the cryopanel to 20 K was about 6 hours with a liquid nitrogen consumption rate of about 35 L/hr. The maximum pumping speed of the cryosorption pump for the hydrogen gas measured by the steady pressure method was about 90,000 L/s.

• Journal of Korean Vacuum Science & Technology
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• v.7 no.1
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• pp.1-7
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• 2003

The pressure distributions in the test stand built for developing KSTAR NBI ion sources were obtained using a network system composed of conductance elements modeling the ion source, the neutralizer, and other beam line components. The allowable regime was defined on the coordinates of the gas supply rate to the ion source and the neutralizer, considering the proper conditions of the three critical parameters, the ion source pressure for good arc discharge, the pressure integral in the neutralizer for sufficient neutralization, and the chamber pressure for minimum neutral beam loss. The neutral beam evolution along the path from the ion source extraction grid to the calorimeter through the neutralizer, the bending magnet and the vacuum chamber was estimated for typical pressure distributions.

• The KSFM Journal of Fluid Machinery
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• v.12 no.2
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• pp.31-38
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• 2009

The valve performance has been evaluated from the theoretical equation based on design information such as packing thrust, spring preload and friction coefficient(${\mu}$). The accuracy of those data can be lower than that of vendor's initial design data. Especially, the friction coefficient can be degraded with time than the original condition and the valve performance calculated using the previous friction coefficient can not be available. Accordingly, this paper is describing a new performance evaluation method of valve based on diagnostic test data which are acquired from a site valve tested in static and dynamic conditions. Especially, this paper provides a new method using friction coefficient(${\mu}$) which is derived from the diagnostic test data acquired in the valve's design basis condition.

• Journal of Korean Institute of Industrial Engineers
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• v.15 no.1
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• pp.51-63
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• 1989

This paper considers software release problems based on Goel-Okumoto and S-shaped reliability growth models. Test of the software system is terminated after a preassigned time T, and it is released to the operational phase. It is assumed that correction cost of an error is increasing with test or operation time. Optimum software release time is obtained using total expected cost on the software life time as a criterion for optimization. In addition, optimal software release policies under the constraint of a software reliability requirement are discussed.