• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.2
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• pp.279-284
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• 2013

In this paper, to evaluate the performance of solenoidal typed injector, research and development had been performed on injector controller in order to respond to various performance tests, which is not only economical but easy extensible on its channels. The developed controller based on embedded system is able to precisely control the injection timing and quantity by high-pressured from the injector. Also, it is able to performance evaluation by measuring the electrical characteristics of solenoid. Additionally, it is enable precision timing control of light source and high speed camera as it is able to precisely photograph the timely spray pattern of injector.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.687-690
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• 2009

본 연구에서는 가스 하이드레이트 형성과정에서 발생할 수 있는 유도지체시간을 줄이고 전체 가스 저장량과 반응 속도의 향상을 위하여 이류체 분사 방식을 이용하여 물분자의 액적을 최소화하는 실험을 통하여, 미세액적 분사에 따른 하이드레이트 형성 시간을 확인하였으며, 반응기 내부의 온도 변화를 확인하여 반응기 내부의 하이드레이트 형성 거동을 확인하고 이를 통하여 상용화를 위한 반응기 설계의 기초 자료로 활용하고자 하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.83-85
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• 2007

멀티패스 프린팅 기법은 원하는 해상도와 오류를 보상하기 위해서 디지털 인쇄 연구 분야에서 일반적으로 사용되는 기술이다. 그러나 고속 및 고해상도의 인쇄품질을 요구하는 현실에서 건조시간 단축과 근접 잉크의 분사가 인쇄품질을 저하시키는 등 다양한 문제점이 발생되고 있다. 따라서 본 논문에서는 멀티패스 프린팅 방법에서 문제점으로 제기되는 건조시간과 인접잉크의 분사에 따른 응집력에 의한 인쇄품질의 저하를 줄이기 위하여 출력영역의 이분분할 방법을 사용하여 분사함으로서 이미지의 출력품질을 향상시키는 방법을 제안한다.

• Journal of the Korean Institute of Gas
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• v.22 no.5
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• pp.18-23
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• 2018

This study tries to analyze the injection amount of injector according to the external environment temperature of CNG vehicle. Especially, We investigated the effect of low temperature environment on gas injector performance by measuring the variation of injection amount under the same conditions as in coldstart condition. This experimental compared two products with different spring characteristics. The experimental device consist of a fuel supply unit, a flowrate measurement unit, a temperature chamber, and an injector control unit (ECU). According to the test result, the initial injection amount of the injector is increased in the low temperature environment and the needle opening time is delayed according to the change of the spring length.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.9
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• pp.569-576
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• 2016

The objective of this study was to investigate, using a numerical method, the fuel injection targeting for improving the combustion performance in a HSDI diesel engine. In this work, the ECFM-3Z model was applied as the combustion model, and the injection mass, inclined spray angle, and injection timing were varied for the study on the targeting of fuel spray. The results of this work were compared in terms of cylinder pressure, rate of heat release, and exhaust emissions characteristics. It was found that the cylinder pressure increased when the injection timing was advanced, and the rate of heat release increased when more fuel was injected into the piston bowl. In addition, $NO_x$ emission increased owing to the increase in the rate of heat release. On the other hand, CO and soot emissions decreased because of the improvement in combustion performance.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.4
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• pp.148-154
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• 2016

A study on the micro particle blasting was conducted to find the optimum conditions of the blasted surface of aluminum 6061. The particle type such as $Al_2O_3$ and SiC, nozzle diameter, pressure, standoff distance and injection time were used as blasting conditions. Statistical method of orthogonal arrays(ANOVA) was used to find optimum conditions of maximum depth and maximum diameter of blasted surface. Particle type, nozzle diameter, and pressure were found to be the main factors of maximum blasted depth and diameter. Maximum blasted diameter was affected by increasing pressure and nozzle diameter but saturated maximum diameter. Maximum blasted depth was affected by pressure and nozzle diameter when aluminum 6061 was blasted with $Al_2O_3$ particle. The value of surface roughness was increased as pressure and nozzle diameter increased when aluminum 6061 was blasted with SiC.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.4
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• pp.73-80
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• 2013

Endothermic fuel utilizing technology is considered as a unique practical method of hypersonic vehicle for long distance flight. Research activities about characteristics of fuel injection and combustion using cracked by endothermic reaction are reviewed. Studies on characterization of supercritical fuel injection and mixing within supersonic flow field are surveyed. Researches on combustion characteristics such as ignition delay time, laminar burning velocity and combustion efficiency at supersonic model combustor are reviewed. In addition, domestic research activities on endothermic fuel are surveyed.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.91-101
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• 2004

With the mathematic linear model of a combustor which consists of a combustion chamber and injectors, the analysis of low frequency dynamic characteristics of a liquld-propellant rocket engine combustor was performed. Propellant mass flowrate was varied by combustion chamber pressure feedback, therefore low frequency oscillation was appeared. Increasing the time constant of a combustion chamber and injector pressure differences and decreasing combustion time delay increased the combustor system stability. The variation of injector time constant little affected stability. The system was always stable, when there was no combustion time delay. Increasing combustion time delay decreased oscillation frequency and damping ratio, and the system eventually became unstable.

• Journal of Aerospace System Engineering
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• v.10 no.4
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• pp.90-97
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• 2016

GEO-KOMPSAT-2A and GEO-KOMPSAT-2B are under development by KARI to replace the COMS mission, and will be launched in 2018 and 2019, respectively. GEO-KOMPSAT-2 will be launched and injected into the GTO (Geostationary Transfer Orbit) by the Ariane V launcher. Once injected into the GTO, the satellites are transferred to the drift orbit by applying a series of apogee engine burns. The burn epoch time, duration, and intervals are selected such that the satellite is placed closest to the target drift longitude, or at the drift start longitude. For GEO-KOMPSAT-2, four or five LAE (Liquid Apogee Engine) burns will be applied for drift orbit injection. This paper establishes the GEO-KOMPSAT-2 LAE burn plan, considering predefined constraints and adjustments, taking into account the perturbing forces. Two approaches have been analyzed: the first is a single shot approach, whereas the other is an iteration based optimal solution. Optimal solution has been obtained using the Focusleop, a geostationary satellite LEOP tool.

• Journal of Astronomy and Space Sciences
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• v.16 no.2
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• pp.265-272
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• 1999

A thrusters modulation method is suggested for spacecraft attitude control with asymmetric configured thrusters during orbit adjustment maneuvers. Attitude is controlled by thrusters off-modulation during orbit maneuvers. Usual control method for symmetric configured thrusters cam not be applied for asymmetric configured thrusters. Disturbance induced from thrusters asymmetricity shall be compensated during pulsing. In this paper, a thrusters control method using null solution is suggested, which is shown working well without inducing disturbance.