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항공기 외장형 정찰 장비용 냉각 시스템의 성능 특성에 관한 실험적 연구
정대윤,이행복,Jung, Daeyoon,Lee, Hang Bok 한국군사과학기술학회 2013 한국군사과학기술학회지 Vol.16 No.1
In this paper, we have proposed a vapor cycle refrigeration system as a cooling system to provide cooling air to the aircraft external reconnaissance stores. In the proposed vapor cycle system, receiver which prevents refrigerant from subcooling was eliminated and thermal expansion valve was replaced with electronic expansion valve. The vapor cycle refrigeration system is aimed to provide cooling air to the reconnaissance stores which is added to the aircraft in the form of external store. The wide temperature range of ambient air from the flight conditions can decrease the cooling performance and can make the refrigeration system unstable in low ambient temperature. Performance characteristics of the vapor cycle refrigeration system has been experimented under air conditions which is derived from the flight envelope. From the experiments, the vapor cycle refrigeration system has been proved to provide enough cooling air to the reconnaissance equipment and to be stable under all the flight conditions.
차종현,김태환,배지열,김태일,정대윤,조형희,Cha, Jong Hyun,Kim, Taehwan,Bae, Ji-Yeul,Kim, Taeil,Jung, Daeyoon,Cho, Hyung Hee 한국군사과학기술학회 2014 한국군사과학기술학회지 Vol.17 No.4
Stealth technology of combat aircraft is most significant capability in recent air battlefield. As the detector of IR missiles is being developed, IR stealth capability which is evaluated by IR signature level become more important than it was in previous generation. Among IR signature of aircraft from various sources, aerodynamic heating dominates in long-wavelength IR spectrum of $8{\sim}12{\mu}m$. Skin temperature change by aerodynamic heating which is derived by effects of Mach number and structure. The 4th and 5th generation aircraft are selected for calculation of the skin temperature, and its height and velocity in numerical conditions are 10,000 m and Ma 0.9~1.9 respectively. Aircraft skin temperature is calculated by computing convection of fluid and conduction, convection and radiation of surface. As the aircraft accelerates to higher Mach number, maximum skin temperature increases more rapidly than average temperature and temperature distribution changes in more sharp, interactive ways. The 4th generation aircraft whose shape is more complex than that of the 5th generation aircraft have complicated temperature distribution. On the other hand, the 5th generation aircraft whose shape is relatively simple shows plain temperature distribution and lower skin temperature in terms of both average and maximum value.
김태환,송지운,차종현,배지열,정대윤,조형희,Kim, Taehwan,Song, Jiwoon,Cha, Jong Hyun,Bae, Ji-Yeul,Jung, Daeyoon,Cho, Hyung Hee 한국군사과학기술학회 2014 한국군사과학기술학회지 Vol.17 No.4
Infrared(IR) guided heat-seeking missiles uses IR emissions from aircraft to detect and track a target. Due to passive characteristic of the IR guidance, early detection of the missile is difficult and it is significant threat to aircraft survivability. Therefore, IR signature prediction of the aircraft is an important aspect of the stealth technology. In this study, we simulated IR signature of the aircraft in real atmospheric conditions. Aircraft surface temperature distribution was calculated by using RadthermIR code. Based on temperature distribution, IR radiance and BRDF(Bidirectional Reflectance Distribution Function) image were simulated for different weather(seasonal) and background(sky/soil) conditions. The IR contrast tendencies are not aligned with surface temperature or magnitude of target IR radiance. Therefore, it is essential to simulate IR signature with various conditions and background to acquire reliable database.
통합해석기법을 활용한 공대공 및 지대공 적외선 미사일 대응 초음속 항공기의 중적외선 및 원적외선 신호 분석
김태환,배지열,김태일,정대윤,황창수,조형희,Kim, Taehwan,Bae, Ji-Yeul,Kim, Taeil,Jung, Daeyoon,Hwang, Chang Su,Cho, Hyung Hee 한국군사과학기술학회 2014 한국군사과학기술학회지 Vol.17 No.6
The stealth performance of supersonic aircraft in recent air battlefield is one of the most significant feature for latest fighters. Especially, as the technology is advancing, the IR stealth capability becomes more important because of its passive characteristic. To design an aircraft with stealth capability, we must know how much the IR signature is generated from the aircraft. Also, predicting the IR signature of enemy's aircraft is tactically crucial. In this study, we calculated MWIR and LWIR infrared signature of $5^{th}$ generation supersonic aircraft against air-to-air and surface-to-air threat using IR simulation code and CFD coupled procedure.
김지혁(Jihyuk Kim),김태환(Taehwan Kim),배지열(Jiyeul Bae),정대윤(Daeyoon Jung),조형희(Hyung Hee Cho) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.11
일차원 전도를 전제로 하는 비정상열유속기법에서 반무한체 가정의 타당성을 검증하기 위해 수치해석적/실험적 연구가 수행되었다. 5 mm의 두께의 낮은 전도성 판이 설치된 쐐기형 시편에 대해 수치해석 및 실험을 수행하였다. 수치해석을 이용해 시간에 따른 판 내부의 온도 프로파일과 최대 허용 실험시간을 확인하였다. 이후 실험을 통해 최대 허용 실험 시간을 평가하고 수치해석 결과와 비교하였다. Both numerical and experimental studies are conducted to verify semi-infinite body assumption in transient heat flux method which based on one-dimensional conduction. Temperature profile and allowable operating time of the low conductivity plate having a thickness of 5 mm are investigated with numerical simulation. Maximum allowable testing time which measured from experiment is evaluated and compared with that of numerical simulation.