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T-103 훈련기의 환기와 난방 시스템 개선에 관한 연구
정대한,Jung, Daehan 한국군사과학기술학회 2013 한국군사과학기술학회지 Vol.16 No.3
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.
날아가는 섬광탄이 연료탱크 수평핀에 미치는 복사열전달 연구
정대한,강치행,김시태,Jung, Daehan,Kang, Chihang,Kim, Sitae 한국군사과학기술학회 2014 한국군사과학기술학회지 Vol.17 No.2
In this paper, the effect of unsteady radiation on the horizontal fin of an external fuel tank by flame of a flying flare was analysed to see the temperature increase of the fin and the thermal impact on the fin. Radiation between two surfaces was calculated using the concept of radiation resistance of surface and space including radiation, irradiation and shape factor for two flying trajectories of a flare, maximum temperature of 2200 K, emissivity of 0.95, flying velocity of 30 m/s, and thermal surface area of $0.01m^2$. The result shows that the temperature increase of the fin is 0.236 K, and the thermal effect on the fin is ignorable. And it was found that temperature is increased a little because small amount of heat energy can be radiated due to the short exposure time to the heat source.
K0-0 항공기 사출좌석 부품에서 발생한 입계균열에 대한 연구
윤용인(Yonug-In Yoon),박준한(Jun-Han Park),손경숙(Kyung Suk Sohn),정대한(Daehan Jung) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
K0-0 which has a turboprop engine of 950 hp is a first aircraft developed by Korean technology and is used a training aircraft for Republic of Korea Air Force's pilots. The localization rate of K0-0 is 65% but a ejection seat for emergency escape is made in Martin-Baker Co. of England. It happened a failure on HPRU(Harness Power Retraction Unit) go-forward torque bar which is a K0-0 aircraft's part of ejection seat in 2008 April. It happened a crack on shaft of a HPRU's part which select manual lock or unlock and HPRU is like as safety belt of automobile. As a result of failure analysis, failure mode is grain boundary fracture and root cause of failure is due to lead segregation in lead-brass.
알루미늄 2024 표적에 대한 HE 탄두 파편의 관통 특성 연구
김득수(Deuksu Kim),강순부(Sunbu Kang),정대한(Daehan Jung),정영진(Youngjin Chung),박용헌(Yongheon Park),박세권(Seikwon Park),황창수(Changsu Hwang) 한국항공우주학회 2018 韓國航空宇宙學會誌 Vol.46 No.3
본 논문은 한국형 전투기 개발 시 적의 위협에 대한 취약성 분석을 위해 요구되는 고속관통자가 표적을 관통하는 기구에 대해 수치 해석적으로 연구한 결과이다. 표적은 1 mm~6.3mm 두께를 갖는 준 무한평면의 알루미늄(Aluminum) 2024 재질을 고려하였다. 관통자는 반구형 노즈 형상을 갖는 강(steel) 재질로, 입사속도는 350~3353 m/s까지, 질량은 0.32~16g까지 갖는 것으로 고려하였다. 수치해석을 위해 사용된 실 사격 데이터는 THOR 방정식으로부터 추정하여 유추하였다. 수치해석 결과 표적을 관통하는 과정에서 관통자의 탄도한 계속도는 관통자의 질량에 대한 지수 함수적으로 감소하는 수식으로 형식화(closed form of formalization) 하였다. 관통 후 잔류속도 및 잔류질량은 표적의 두께와 관통자의 질량 및 입사속도에 의존된 지수 함수적으로 감소하는 수식으로 각각 형식화하였다. We have studied the damage mechanism of a metallic thin plate by the highly energetic fragments generated from high explosive(HE) warhead. The penetration process has presumed that the velocity of a fragment is in the range of 350 m/s to 3353 m/s, the thickness of Aluminum 2024 target plate is in the range of 1 mm~6.3 mm thick. The mass of fragment with hemisphere nose shape is in the range of 0.32 g to 16 g. The analytical solution for penetration process has been derived by using the report of the project THOR. The results of analysis implied that the closed forms by an exponentially decay function well fit the change of the ballistic limit velocity, loss velocity and loss mass of fragment as the mass of fragment and the thickness of target plate increase.
실린더형 HE 탄두 폭발 시 파편의 속도 및 발사각 추정방법 연구
황창수(Changsu Hwang),박용헌(Younghyun Park),박세권(Seikwon Park),정대한(Daehan Jung),이문식(Moonsik Lee),강순부(Sunbu Kang),김득수(Deuksu Kim) 한국항공우주학회 2019 韓國航空宇宙學會誌 Vol.47 No.12
본 연구는 항공기에 근접하여 폭발하는 고폭형 위협 무기의 파편 발사속도 및 발사각을 수치 해석적으로 추정한 결과이다. 고폭형 위협 무기에 대한 항공기의 취약성을 평가하기 위하여 탄두 구성품의 물리량을 이해하는 것은 매우 중요하다. 일반적으로 고폭형 위협 무기에 대한 구성품의 질량, 길이 및 직경 등 물리적 변수는 알려져 있지 않다. Terrier, Sparrow 등 유사 위협 무기들의 데이터를 이용하여 charge to mass 비율, 길이와 직경 비율 등과 관련된 경험식을 수치 해석적으로 유도하였다. 근접신관에 의하여 외부에 폭발하는 탄두에서 탄두 덮개 구성비는 20% 수준으로 나타났으며, 고폭 화약의 양쪽 끝부분에서 방사되는 파편의 발사속도 구배 현상이 뚜렷이 나타났지만 법선 방향에 대한 발사각은 6° 이내로 나타났다. We have studied the numerical analysis about the fragment ejection velocity and spray angle when the High Explosive warhead detonated at proximity distance at an aircraft. To study the physical quantities about the warhead components is very important to assessment the vulnerability of aircraft. Generally, the physical quantities about the components of a warhead such as the mass, length, diameter and charge to mass ratio are unknown. Therefore, it is required to estimate the physical quantities by using physical continuities of similar threats. The empirical formulas to understand the dependence among charge to mass ratio, length and diameter ratio were driven by using the physical parameters of similar threatening such as terrier, sparrow. As a result, we confirmed that the dead mass ratio was closed to 20% of warhead mass since the metal case of the proximity threat acts as a simple carrier. This implies that the effective length and diameter of High Explosive Compound is smaller than the length and diameter of warhead, and become a key to understand the large ejection gradient velocity and small spray angle of fragments within 6 degree.