• 한국군사과학기술학회지
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• 제16권3호
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• pp.277-284
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• 2013

In this paper, the ventilating and heating system of T-103 trainer aircraft were investigated and redesigned to improve its poor performance. The ventilation system of the trainer was designed to increase the mass flow rate of fresh air by using air intake valves. The flow-in air through the air intake valve is supplied to the cabin by the ram effect of aircraft and the propeller. And the additional heating system was installed to improve the temperature of the cabin inside. The wasted heat from the exhaust gas of the engines was used as heat source of the additional heating system by installing an heat exchanger around the exhaust nozzle. The additional fresh air and the heated air enter the cabin via two ducts mounted under the instrument panel and behind the pedal in the cabin. The additional ventilating and heating system can be controlled by the first pilot and the secondary pilot individually using the control knob equipped separately. After mounting the additional ventilating and heating system, evaluations such as inspection of parts and component, ground run-up test, in-flight test, user test, etc. were conducted. The result of the tests was sufficient to meet the requirements of the manuals, and the pilots were satisfied with the additionally mounted systems.

• 에너지공학
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• 제14권2호
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• pp.73-81
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• 2005

강판의 냉간압연 후 소둔을 하기 위한 열처리 공정에서 사용되고 있는 Radiant Tube Burner(이하 RT버너) 연비를 개선하기 위한 효율적인 방법을 실험적으로 조사하였다. 재열기가 설치된 모델 RT버너를 실험에 맞도록 개조하여, 배기 중 산소 농도 조건을 변화시키면서 연료 소모에 대한 흡입공기의 온도와 산소분율의 영향도를 파악하였다. 본 연구의 결과, 흡기 온도를 상승시키면 RT버너의 chamber온도가 상승하나 그 상승폭은 흡기 온도 상승폭의 $10\%$에 지나지 많아, 흡입 공기 온도의 상승만으로는 연료 소모 개선을 기대할 수 없다는 것을 알 수 있었다 그러나, 흡입 공기 중 산소분율 변경 실험 결과, 흡입 공기 중의 산소분율을 $1.5\%$증가시키면 NOx의 배출이 약 $40\%$정도 증가하지만 약 $20\%$의 연비 개선 효과를 보였다. 따라서, NOx 배출 증가를 억제하는 산소 고부하 전용 RT버너는 RT버너 시스템의 연료 소모를 개선하는 효과적인 방법의 하나로 기대된다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.992-995
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• 2011

초음속 공기 흡입식 추진시스템(램제트/스크램제트)에 적용되는 공기 흡입구의 성능설계 기법 연구를 수행하여 두 종류의 공기 흡입구에 대한 예비 형상 설계 및 성능해석 모델을 수립하였다. 제시된 모델을 사용하여 축대칭 원추형 공기 흡입구와 2차원 사각형 공기 흡입구의 압축 각도와 충격파 개수에 따른 성능 영향을 평가하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
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• pp.77-83
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• 1996

Noise control process of an air intake system for a four-cylinder automotive engine is described. The objective of the process is reduction of induction noise without losing engine performance and changing package layout. The theory and feasibility for noise control elements are also discussed. In general, four-cylinder engines generate a lower frequency induction noise around 80-150 Hz (2400-4500 rpm) and firing frequency, valve impact noise are the main sources. In this paper, the most problematic noise source is identified first and better position of air inlet is selected between inside-fender and out-of-fender layouts. Secondly, the possible noise control approach and CAE analysis results are compared to those from speaker excitation tests. Finally, the effect of the controlled intake system after the installation to an automobile is presented.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.491-498
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• 2004

Lift Fan Engines of JAXA's conceptual Jet VTOL aircraft have a very small bellmouse shape air intake, which make some differences in aerodynamic design of the blades. To obtain a better rotor or stator blade design, this paper performs a numerical analysis of the throughflow on a lift fan as a two-dimensional axisymmetrical flow. Based on the last report focusing on the air intake's influence on the throughflow, a more realistic bellmouse air intake case is treated to reconsider the influence on the throughflow by the small bellmouse air intake. Three work input patterns are tested to reduce some problematic influences on the throughflow or blade designs. The obtained result shows one of acceptable blade designs for the lift fan engine.

• 동력기계공학회지
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• 제13권4호
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• pp.11-17
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• 2009

This paper deals with the effects of pulsating flow on volumetric efficiency, which may be generated during the gas exchange procedure, due to piston motion, valve event on intake and exhaust stroke and unsteady flow of turbocharger of a three-cylinder four stroke turbo-charged diesel engine. Consequently, volumetric efficiency affects significantly the engine performance; torque characteristics, fuel economy and further to emission and noise level. As the expansion ratio became larger the engine speed varies and torque increases, the pressure pulsation in an exhaust gas pipe acts as an increasing factor of intake air charging capacity totally. The phase and amplitude of pressure pulsation in the intake system only affects volumetric efficiency favorably, if it is well matched and tuned effectively to the engine. Thus, to verify the exact phase and amplitude of the pressure variation is the ultimate solution for the air-flow ratio assessment in the intake stroke. Some experimental results of pressure diagrams in the intake pipe and gas-flow of turbine in-outlet are presented, under various kinds of operating condition.

• 한국자동차공학회논문집
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• 제7권9호
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• pp.63-74
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• 1999

When a fuel was injected with opening the intake valve of a port fuel injection engine, the spray atomization and flow characteristics in the intake port have a strong influence on the mixture formation of a combustion chamber. Thus , this study was to clarify the spray flow characteristics of the air-assist gasoline spray with fine dropkets across the suction air stream in model intake port. For the simulated opening intake valve in port, suction air stream was varied to 10m/s ∼30m/s. And fuel pressur ewas fixed to 300kPa, but air assist pressure was varied to 0∼25kPa for a vairable spray conditions. Spray flow trajectory was investigated by means of laser sheet visualization and the measurements of droplet sizes and velocities were made by PDPA system. Measured droplets within the spray flow field were subdivided into five size groups and then, the flow characteristics of droplet size groups were investigated to the spray across a suction air stream.

• 대한기계학회논문집
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• 제12권6호
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• pp.1358-1371
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• 1988

The combustion process is the most important process in the S.I. engine since it determines performance and emissions. As the flame propagates slowly due to EGR or lean mixture, the fast burn system is widely used in the modern engines in order to improve engine performance. As the basic research for the fast burn system of the S.I engine, this study is aimed to identify the effects of the intake port design on the air motion inside a cylinder. In this study various intake ports were designed and tested. Swirl levels for the different intake ports were measured by a swirl meter and LDv.Also transient air motion inside a cylinder is further investigated following the motion of the boston. Out of the various intake ports tested in this study the masked shroud head (MSH) generates the highest swirl while keeping satisfactory volumetric efficiency. The MSH port also produces high level of turbulence by shearing action between cylinder wall and swirl.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
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• pp.190-193
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• 2005

The air filter in engine intake system filters the dirt in the breathing air but also it attenuates the noise although the phenomenon has been regarded negligible. For the analysis of the acoustical performance of air filter, an acoustical model is suggested in this paper. The air filter consists of a porous filter element, which catches the particulate dirt, and a plastic filter box, which supports the filter element. Fibrous structure of the filter element is modeled as a micro-perforated panel using the flow resistivity and porosity. The pleated geometry of the filter element is modeled as two coupled ducts and a mathematical model is developed for the analysis of sound propagation. The filter box Is modeled as a rigid rectangular box. By combining two models, a 4-pole transfer matrix for the air filter is derived. The transmission loss calculated using the transfer matrix of the suggested model is compared with the measured data. Reasonably good agreement is observed. The result can be improved by considering the visco-thermal effect in modeling, in particular at a frequency range near the troughs of TL curve.

• 한국자동차공학회논문집
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• 제1권2호
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• pp.27-33
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• 1993

Using the solenoid driven gas injection valve, Hydrogen fuel supply system was made. It was attached to a single cylinder research engine and intake port injection type hydrogen fueled S.I. engine was constructed. Engine performance, emission characteristics, and abnormal combustion were studied through the engine test performed with the variations of fuel-air equivalence ratio and spark timing. Compared with gasoline, hydrogen burns so fast that cylinder peak pressure and temperature are higher and NO is emitted more at full load condition. IN the case of intake port injection type engine, COVimep becomes lower due to the well-mixing of air and fuel, and engine output is lower owing to the low volumetric efficiency. As fuel-air equivalence ratio goes up, the combustion speed increases, and COVimep decreases. NO emission peaks slightly lean of stoichiometric. As spark timing advances and fuel-air equivalence ratio goes up, the cylinder peak pressure and temperature become higher, so abnormal combustions take place easily.