• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.79-88
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• 2017

Ignition test of the fuel-rich propellant coated with ignition support material in the ramjet combustor condition was conducted. Ignition delay and flame holding was measured. Fuel grain consist of HTPB mixed with AP particle 15 wt.%, Al particle 5 wt.%. To cause the short ignition delay, ignition support consist of $NC/BKNO_3$ and composite propellant was coated to the fuel grain. Ethanol blended $H_2O_2$ gas generator control the temperature, pressure, $O_2$ concentration in the oxidizer gas in the air. Gas is supplied with mass flux of $200kg/m^2s$. Through the test ignition support operated well and ignition delay of 0.6 second and the Flame was sustained.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.957-967
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• 2017

Firing test of the fuel grain for solid fuel ramjet with additives and ignition support material was conducted. Fuel grain consist of HTPB mixed with AP particle 15 wt.%, Boron particle 5 wt.%. To cause the short ignition delay, ignition support consist of $NC/BKNO_3$ and composite propellant was coated to the fuel grain. An oxidant gas having a controlled temperature, pressure and oxygen composition close to the air condition in the ramjet combustor was supplied using the Ethanol blended $H_2O_2$ gas generator. Gas was set to flow at a mass flow rate of 150 g/s and mass flux of $200kg/m^2s$ in the grain port. Through the test, ignition support operated well and ignition delay of 0.5. During the test, stable chamber pressure with 8 bar and high combustion efficiency of 0.86 was confirmed.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.405-408
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• 2009

공기열원 히트펌프시스템의 문제점, 즉 열효율, 안정성, 착상에 대한 현황을 파악하고 이를 해결하기 위한 연구를 수행하였다. 열효율과 안정성을 위해 기존 시스템을 보완한 8행정 냉매사이클시스템 개발과 제어시스템의 개발을 통해 히트펌프 시스템의 효율을 2배 정도 증가시키고, 안정성을 높이며, 착상 문제를 최소화할 수 있도록 하였다. 개발된 공기열원 히트펌프시스템의 COP는 평균 5정도이고, 안정적으로 운용되는 외부 온도는 $-10^{\circ}C$에서 $55^{\circ}C$까지이다. 토출되는 온수의 온도는 $50{\sim}60^{\circ}C$정도이다. 평균 제상시간은 1분 이내이다. 앞으로 개발해야 할 문제는 외부 온도 $-10^{\circ}C$ 이하지역에서 보조열원 없이 난방을 할 수 있고 친환경 냉매를 사용하며 COP가 7이상인 고효율 히트펌프시스템를 실용화하는 것이다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1995.10b
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• pp.387-392
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• 1995

전기 유압식 좌심실 보조장치에서 모터 전류 파형을 정보로 하여 작동기의 이완기 속도를 조절함으로써 좌심방으로부터 유입되는 혈류량을 조절하는 알고리즘을 개발하였다. 좌심실 보조장치(Left Ventricular Assist Device, LVAD)는 허혈성 심장질환 등으로 좌심실 의 혈액 박출 기능이 저하된 환자에게 시술하여 정상 상태의 심박출량을 유지할 수 있도록 하는 보조 혈액 박출 기능이이다. 전기 유압식 좌심실 보조장치에서는 혈액의 유입이 능동 적으로 이루어지므로, 좌심방 함몰로 인한 심근 손상 및 외부 공기 유입으로 인한 색전증을 방지하기 위해 유입혈류량을 현재 좌심방내의 상태에 따라 적절히 조절해 주어야 한다. 좌 심방 내의 혈액량 정도는 혈액을 유입해 내는 작동기의 이완기 동작 시에 소모되는 에너지 크기에 반영되고, 작동기를 구동하는 모터에 들어가는 전류의 크기는 작동기에 공급되는 에 너지에 비례하므로, 이전류 파형의 정보들을 통해 좌심방내의 상태를 추정해 볼 수 있다. 본 논문에서는 퍼지로직을 적용하여 모터 전류 파형의 정보들을 통해 좌심방 내의 상태를 추정 해 볼 수 있다. 본 논문에서는 퍼지로직을 적용하여 모터 전류 파형의 이상 유무를 판단한 뒤 에에 따라 작동기의 이완기 속도를 조절하는 알고리즘을 개발하여 모의순환장치 실험을 통해 그 실효성을 검증한 결과를 정리하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.131.1-131
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• 2001

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.187-197
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• 1998

To investigate the spray behavior and atomization characteristics using an air-assist injector, spray visualization and PDPA measurements were carried out under the various assisted air pressures and the fixed fuel pressure. The air assist pintle type injector employed in this study is consisted of the air assist adaptor and an injector housing using the gasoline fuel and air as the working fluids. As results, increasing pressure of assisted air, the growth of spray tip penetration is gradually reduced at the end of spray and spray angle is steadily increased at the main spray region except from the early spray. For the air assist pressure of 25㎪ in a spray downstream, it is doncluded that droplet size distribution shows the peak of 10${\mu}{\textrm}{m}$ and most of the droplet sizes are less than 50${\mu}{\textrm}{m}$. Also, the air-assist injector extremely improves fuel atomization in order to produce much finer droplets, it shows that approximately, in this case, 50% decreade of SMD than without air assit.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.1
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• pp.92-103
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• 1999

The fuel spray behavior in the intake port of an electronic control port irijection gasoline engine has a strong influence on engine performance, exhaust emission and fuel consumption. Thus, in this study, fuel spray behavior and flow characteristics of the air assist gasoline spray injected into a suction flow in a simulated rectangular intake port have boon investigated. Macro-behavior of spray characteristics was investigated by means of visualization and the measurements of SMD and velocity were made by PDPA. For analysis the flow field with droplets size, droplets are classified five droplets size groups. As a result, the normal distance of suction flow increasing, the relatively large droplets distribution and SMD increase because small droplets easily follow suction flow. Near impinging wail, after impinging against the wall, secondary atomized small droplets of D < $30{\mu}m$ bound from the wall. And the increasement of suction flow progress to the large droplets of D > $100{\mu}m$ distribution. Therefore, SMD are apparently increased near impinging wall, Z/d = 9.0.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.20-27
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• 2000

Characteristics of two favorite injection tools for gasoline direct injection application were compared. An air-assisted fuel injector (AAFI) and a high-pressure swirl injector (HPSI) were designed and fabricated for prototype development, and the characterization strategies and processes for both injection tool have been arranged in parallel. Characterization works were carried out mainly through measurements, and in some cases, computational fluid dynamic analysis was utilized. In this paper, overall characteristics defined as flow rate, spray pattern, penetration, internal spray structure and drop size distribution, was discussed. The AAFI was found to be advantageous in flexibility of fuel flow rate, and the HPSI in stability and precision. Spray shape factor was introduced to describe the development of intermittent sprays from both injectors. Axial penetration appeared to be almost linear in the case of the AAFI while its speed continuously decreased with time in the HPSI.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.28-35
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• 2000

As a second part of the comparison study, microscopic features of an air-assisted fuel injector(AAFI) and a high-pressure swirl injector (HPSI) were characterized. They consist of the internal spray structure in terms of fuel mass and drop diameter, the overall atomization performance with respect to operating parameters and the drop size distribution. Large droplets are concentrated in around the head part of a spray field of the HPSI, while in the case of the AAFI, they were distributed in the tail part. Although the AAFI showed the better atomization performance, the feasible ranges of operating parameters such as injection and ambient pressure were found to be wider in the HPSI. Drop size distribution of the AAFI sprays was more dispersed than that of the HPSI. Drop size distribution of the AAFI sprays was more dispersed than that of the HPSI. However, at the well-atomized condition, it appeared to be very uniform.

• Journal of ILASS-Korea
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• v.3 no.4
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• pp.58-64
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• 1998

In the gasoline engine of fuel injection type, atomization of fuel droplet and its distribution has directly influenced the performance of engine and harmful emission. To investigate atomization characteristics of fuel spray, in this paper fuel spray of air-assisted injector is observed at the various initial conditions of ambient air temperature and air assisted pressure. Behavior of fuel spray is photographed with microscopic visualization system. The SMD of fuel droplet is measured with PMAS (Particle Motion Analysis System). The effect of air-assisted pressure and temperature of ambient air resulted in the decrement of SMD and its variation. Finally, It was found that It was found that from spray angle at the two-hole injector had measured $20{\pm}4$ degree the result of photographs by shadow graphy. The mean diameter of suns decreased and the of droplets increased with increasing the temperature in the spray fields by the results of PMAS measurement. It was found that the characteristics of sprays became finer by increasing the temperature of spray fields about 373K without the delivery of air-assistance.