• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.05a
• /
• pp.197-201
• /
• 2010

Precise control of oxidizer mass flow rate is important for hybrid rocket thrust control. In this study, oxidizer mass flow rate control system is developed by using stepping motor which is controlled by Labview program. Gox is used for oxidizer and PolyCarbonate, PolyEthylene, and PMMA is used for solid propellant. To suppress thrust oscillation during thrust control experiment, schematics of the experiment is analysised and revised. Results show that thrust oscillation is suppressed successfully.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.492-495
• /
• 2008

As the obesity patients increase recently, breath disease such an OSA(obstructive sleep apnea) is also increasing. When the breath disease occurs, the risk comes to be high. Dependence degree the PAP(positive airway pressure) is also coming to be high. The mechanical simulator is composed cylinder, valve, ball screw and the motor that they correspond to the lung and airway, the diaphragm of the human. In order to confirm the characteristic of the motor and the valve, it accomplished an test. The simulator traces breath pattern against the normal breath and the OSA.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.2
• /
• pp.150-158
• /
• 2002

Through experimental works, the damping force vibration problem was investigated, which results from valve and surge pressure in the oil return line of the hydraulic circuit of an active suspension system in a passenger cu. Experiments were carried out under passive system, where an orifice valve was closed and non-active system, where an orifice valve was opened, using a pressure control valve controlled by solenoid. The effects of parameters of the valve overlap and accumulator on smoothing surge pressure was elucidated. It was proved that the apparent variation of damping force due to the overlap amount of pressure control valve is the most important factor to control the damping force variation. The procedure of the experimental works shows the development process of a proportional pressure control valve in the hydraulics system of an active suspension system of passenger car.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.05a
• /
• pp.268-271
• /
• 2008

In order to understand mixing characteristics of the APU combustor, sector combustor which size is 1/6 of the real combustor was manufactured. To see the inner side of combustor, Poly Carbonate material is used as a combustor riner. Turbo blower is used as a air supplying device and valves are used as controling the air flow. Maximum flow rate of the blower is 7 $m^3$/min and maximum inlet velocity is up to 100 m/s.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.05a
• /
• pp.67-70
• /
• 2009

Because many research using rocket grade peroxide is studied, distillation method for domestic production of rocket grade hydrogen peroxide is required. Distillation methods are very various and divided by feeding method, distillation time, distillation pressure, and so on. Among these, vacuum distillation is a suitable method for hydrogen peroxide. This method can reduce thermal decomposition and reaction with impurities. Distillation condition is determined by Raoult's law. Low vacuum level and vacuum level control are appeared as important problems of the experiment equipment, which are solved by using less leakage vacuum chamber and metering valve.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.4
• /
• pp.316-322
• /
• 2007

The EHA(Electro-hydrostatic Actuator) reveals completely different characteristics from the conventional valve-controlled Electro-hydraulic actuators. In this paper, its mathematical model including nonlinear elements was derived to be verified by experiments. Based on this, a simulation program was developed for the EHAs consisting of an electric motor driven hydraulic pump, pipe lines and a cylinder. The influence of important design parameters such as peak motor torque and rotational inertia moment of the hydraulic pump on control performance was investigated, where the test condition was intentionally selected so that the motor torque was saturated during the transient phase. As a result, design requirements for improving the control accuracy under full speed operation conditions of the EHAs were investigated.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.7
• /
• pp.57-62
• /
• 2014

This study presented the feasibility of a coolant heat-source heat pump system as an alternative heating system for electrically driven vehicles. Heat pumps are among the most environmentally friendly and efficient heating technologies in residential buildings. In various countries, electric mobiles devices such as EV, PHEV, and FCEV, have been mainly concerned with heat pumps for new mobile markets. The experiments herein were conducted for various ambient temperatures and coolant temperatures to reflect the winter season. The system, a coolant heat-source heat pump, consisted of an inside heat exchanger, an outside heat exchanger, a motor driven compressor, an electronic expansion valve, and plumbing parts. For the experimental results, the maximum heating capacity and air discharge temperature are up to 6.3 kW and $62^{\circ}C$ respectively at an ambient temperature of $10^{\circ}C$, and coolant at $10^{\circ}C$. However, at $-20^{\circ}C$ ambient temperature and $-10^{\circ}C$ coolant temperature, conditions were insufficient to warm the cabin as the air discharge temperature was $13^{\circ}C$.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.5
• /
• pp.650-658
• /
• 1997

Analysis and control of intake charge motion such as swirl and tumble are very important factors in improving the gasoline engine performance. In this paper, single-frame PTV (particle tracking velocimetry) is used to investigate intake tumble patterns in a steady flow test rig of gasoline engine with dual-intake-valve and pent-roof combustion chamber. Intake tumble pattern is quantified in accordance with blockage ratio of TIV (tumble intensifying valve) with single- frame PTv.The view of the instantaneous 2-D velocity field gives a realistic understanding of in-cylinder flow field. Thus it is confirmed that PTV is a effective tool in engine design. In conventional port, two tumble structures appear clearly, and the larger one is observed under the exhaust valve side and the smaller is right below the intake valve side. The larger vorticity is observed in TIV port, thus it is concluded that TIV have an effect on intensified tumble motion in cylinder flow.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.10a
• /
• pp.251-254
• /
• 2004

Hybrid rockets have many advantages over solid and liquid rockets. Hybrid rockets put forth high $I_{sp}$ like liquid rockets in spite of simple structure and low cost. As oxidizer flow rate is increased, thrust of hybrid rocket is increased accordingly. In this study, lab-scale hybrid rocket is designed, fabricated and tested. This system consists of lab-scale hybrid rocket motor, ignition system, flow system and data aquisition system. In order to control oxidizer flow rate, we construct flow rate control system by using needle valve and stepping motor.

• Transactions of the Korean hydrogen and new energy society
• /
• v.19 no.4
• /
• pp.331-339
• /
• 2008

본 논문은 내경 7.73 mm와 5.80mm의 수평관내 프레온계 냉매 R-22와 탄화수소계 냉매 R-290과 600a의 응축 열전달 계수의 실험적 결과를 나타내었다. 실험장치는 압축기, 응축기, 팽창밸브, 증발기 등으로 구성된다. 응축 실험은 질량유속 $35.5{\sim}210.4\;kg/m^2s$이고, 응축온도 40$^{\circ}C$인 조건에서 수행하였다. 주요 결과를 요약하면 다음과 같다. 탄화수소계 냉매 R-290과 R-600a의 평균 열전달 계수는 프레온계 냉매 R-22보다 높게 나타났으며, R-600a의 평균 열전달 계수가 모든 관경에 대해 가장 높게 나타났다. 실험결과와 종래의 상관식을 비교한 결과, 모든 관경과 냉매에 대해 Haraguchi 등의 상관식이 가장 좋은 일치를 보였다. 그 중에서 Cavallini-Zecchin의 상관식은 7.73 mm 관경의 실험데이터와, Dobson 등의 상관식은 내경 5.80 mm 관경의 데이터와 좋은 일치를 보였다.