• Title/Summary/Keyword: defense R&D test development

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A miniaturized turn-counting sensor using geomagnetism for small-caliber ammunition fuzes (지구자기장을 이용한 소구경 탄약 신관용 소형 회전수 계수 센서)

  • Yoon, Sang-Hee;Lee, Seok-Woo;Lee, Young-Ho;Oh, Jong-Soo
    • Journal of Sensor Science and Technology
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    • v.16 no.1
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    • pp.17-23
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    • 2007
  • This paper presents a miniaturized turn-counting sensor (TCS) where the geomagnetism and high-rpm rotation of ammunition are used to detect the turn number of ammunition for applications to small-caliber turn-counting fuzes. The TCS, composed of cores and a coil, has a robust structure with no moving part for increasing the shock survivability in the gunfire environments of ${\sim}30,000$ g's. The TCS is designed on the basis of the simulation results of an electromagnetic analysis tool, $Maxwell^{(R)}$3D. In experimental study, the static TCS test using a solenoid-coil apparatus and the dynamic TCS test (firing test) have been made. The presented TCS has shown that the induction voltage of $6.5{\;}mV_{P-P}$ is generated at the magnetic flux density of 0.05 mT and the rotational velocity of 30,000 rpm. From the measured signal, the TCS has shown the SNR of 44.0 dB, the nonlinearity of 0.59 % and the frequency-normalized sensitivity of $0.26{\pm}0.01{\;}V/T{\cdot}Hz$ in the temperature range of $-30{\sim}+43^{\circ}C$. Firing test has shown that the TCS can be used as a turn-counting sensor for small-caliber ammunition, verifying the shock survivability of TCS in high-g environments.

Measurement of Performance of High Speed Underwater Vehicle with Solid Rocket Motor(II) (로켓추진을 이용한 고속 수중운동체의 수중 주행성능 측정 결과(II))

  • Yoon, Hyun-Gull;Lee, Hoy-Nam;Cha, Jung-Min;Lim, Seol;Suh, Suhk-Hoon
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.4
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    • pp.12-17
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    • 2018
  • A natural cavitation-type high-speed underwater vehicle with solid rocket motor is tested, and its speed and running distance are measured. The outputs from pressure sensors on the surface of the vehicle reveal a pressure-time history reflecting the development of supercavitation. Underwater cameras installed on the wall of the test pool record the entire process from the onset of supercavitation to its full development. CNU-SuperCT, based on two-dimensional inviscid theoretical analysis, is used to simulate test results. Considering CNU-SuperCT does not include the control fins of the vehicle, simulation results agree with test results very well. Additionally, pictures from underwater cameras support the test results.

Aeroelastic Compatibility Substantiation of Aircraft External Stores Using the Dynamic Characteristic Data from Ground Vibration Test (지상진동시험 동특성 데이터를 활용한 항공기 외부장착물의 공력탄성학적 적합성 입증)

  • Lim, Hyun Tae;Kwon, Jae Ryong;Byun, Kwan Hwa;Kim, Hee Joong;Kim, Jae hoon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.45 no.4
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    • pp.269-275
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    • 2017
  • The aeroelastic stability of a fighter type aircraft can be severly affected by the store mass, aerodynamic characteristics, and store combinations. Hence, the stability for the all store configurations must be substantiated before the aircraft in service. For the aeroelastic analysis, the design data and information for the aircraft structure, mass distribution, control surface characteristics, and external shape etc. are required. This is the reason that the store compatibility substantiations by a third party are restricted. However, according to the change of operational environment or the improvement of avionic technology, a new external store is developed and it should be installed on an aircraft without the support from the original supplier. This paper describe the process to substantiate the aeroelastic compatibility between a new external store and an imported aircraft whose design data is not available to a third party operating the aircraft.

Design of Control Logic, and Experiment for Large Torque CMG (대형 토크 제어모멘트자이로의 제어로직 설계 및 실험)

  • Lee, Jong-Kuk;Song, Tae-Seong;Kang, Jeong-Min;Song, Deok-Ki;Kwon, Jun-Beom;Seo, Joong-Bo;Oh, Hwa-Suk;Cheon, Dong-Ik;Park, Sang-Sup;Lee, Jun-Yong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.4
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    • pp.291-299
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    • 2021
  • This paper presents the control logic for the momentum wheel and gimbals in the CMG system. First, the design of the control logic for the momentum wheel is described in consideration of the power consumption and stability. Second, the design of the control logic for the gimbals considering the resonance of the vibration absorber and stability is explained. Third, the measurement configuration for the force and torque generated by the CMG is described. Fourth, the results of the frequency and time response test of the momentum wheel and gimbals are shown. Last, the measurements of the force and the torque generated through the CMG are explained.

1-D Analysis for Water Spray Cooling of Exhaust Gas in Combustor Test Facility (물 분무를 이용한 연소가스 냉각 1차원 해석)

  • Im, Ju Hyun;Kim, Myung Ho;Kim, Yeong Ryeon
    • Journal of the Korean Society of Propulsion Engineers
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    • v.19 no.1
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    • pp.61-67
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    • 2015
  • The cooling of hot exhaust gas is an important issue for the construction of combustor test facility. Water spray is an effective method for exhaust gas cooling due to its large latent heat in process of evaporation. In this study, 1-D analysis has been performed based on continuity, energy conservation, and saturated vapor property to understand water spray cooling of combustion gas. In the exhaust duct of combustor test facility, the injected water decreases combustion gas temperature, and evaporates in the combustion gas. However, some of the injected water is collected in the sump due to condensation. The evaporation of water helps combustion gas cooling, but causes pressure increase inside the exhaust duct due to increase of vapor pressure. These phenomena has been analyzed by 1-D modeling in this study. From 1-D analysis, the adequate mass flow rate of water spray to cool combustion gas and to avoid excessive pressure rise inside the exhaust duct has been decided.

Study on the Method to Improve a Maritime Safety by Analysing the Distribution Characteristics of the Ships on Marine Firing Range (해상사격장 선박분포 특성 분석을 통한 해상안전 개선방안에 대한 연구)

  • Baek, Sang Hwa;Lee, Ah Yoon;Park, Ho Jun;Lee, Woo Sung;Choi, Kye Soog
    • Journal of the Korean Society of Safety
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    • v.35 no.3
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    • pp.79-85
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    • 2020
  • Ahn-heung Proving Ground(APG) of Agency for Defense Development(ADD) is the only weapon test site which has been performing firing tests for many kinds of missile, artillery and ammunition. APG has been performing the firing tests of so many times every year. The tests related to missiles, artillery and ammunitions cover 80% among the quantity of annual test events. The target area of many kinds of missile, artillery and ammunition is on the sea. Therefore, APG has its marine firing ranges which were approved by the ministry of Defense. Both weapons and ships can run into each other on the sea. APG has to monitor and detect the positions of the ships in the specific dangerous zone on the sea. The positions of the ships are detected by Scanter 2001 radar and GPS100 detection radar. Evading the time period when the ships appear very often on the sea may be a good solution to keep the maritime safety. And evading the place where the ships appear very often on the sea may be a good solution as well. This paper is to analyze the ships' distribution characteristics of marine firing range, which are to raise the efficiency of many kinds firing tests which have been performed in APG of ADD. Ship distribution data from February 2014 to December 2016 were used in this paper. Ship distribution was analyzed with monthly data, seasonal data and etc. The number of the ships in approved sea area is higher in the morning than in the afternoon, and in fall than other seasons, and from August to November, and below 0.5 m in the hight of wave. Using the these conditions, we can raise the test efficiency of many kinds firing tests and guarantee maritime safety. The number of the ships in approved sea area is entirely unrelated to visibility of the sea. The time period when the number of the ships are high on the sea is morning. The season when the number of the ships are comparatively high on the sea is fall. APG of ADD could raise the efficiency of the firing tests and improve the maritime safety, using the analysis results of the characteristics on the ship distribution.

Finite Element Analysis Through Mechanical Property Test and Elasto-plastic Modeling of 2.5D Cf/SiCm Composite Analysis (2.5D Cf/SiCm 복합재의 기계적 물성 시험과 탄소성 모델링을 통한 유한요소해석)

  • Lee, MinJung;Kim, Yeontae;Lee, YeonGwan
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.9
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    • pp.663-670
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    • 2020
  • A study on mechanical property characterization and modeling technique was carried out to approximate the behaviour of structures with 2.5D C/SiC material. Several tensile tests were performed to analyze the behaviour characteristics of the 2.5D C/SiC material and elastic property was characterized by applying a mathematical homogenization and a modified rule of mixture. SiC matrix representing the elasto-plastic behavior approximates as a bilinear function. Then the equivalent yield strength and equivalent plastic stiffness were calculated by minimizing errors in experiment and approximation. RVE(Representative Volume Element)was defined from the fiber and matrix configuration of 2.5D C/SiC and a process of calculating the effective stiffness matrix by applying the modified rule of mixture to RVE was implemented in the ABAQUS User-defined subroutine. Finite element analysis was performed by applying the mechanical properties of fiber and matrix calculated based on the proposed process, and the results were in good agreement with the experimental results.

Microstructure and Mechanical Properties of the High-Hardness Armor Steels (고경도 철계 장갑재의 미세조직과 기계적 특성 분석)

  • Lee, Ji-Min;Han, Jong-Ju;Song, Young-Beum;Ham, Jin-Hee;Kim, Hong-Kyu;Hwang, Byoungchul
    • Korean Journal of Materials Research
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    • v.28 no.8
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    • pp.459-465
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    • 2018
  • This paper presents a study of the microstructure and mechanical properties of commercial high-hardness armor (HHA) steels tempered at different temperatures. Although the as-received specimens of all the steels exhibit a tempered martensite structure with lath type morphology, the A steel, which has the smallest carbon content, had the lowest hardness due to reduced solid solution hardening and larger lath thickness, irrespective of tempering conditions. As the tempering temperature increases, the hardness of the steels steadily decreases because dislocation density decreases and the lath thickness of martensite increases due to recovery and over-aging effects. When the variations in hardness plotted as a function of tempering temperature are compared with the hardness of the as-received specimens, it seems that the B steel, which has the highest yield and tensile strengths, is fabricated by quenching, while the other steels are fabricated by quenching and tempering. On the other hand, the impact properties of the steels are affected by specimen orientation and test temperature as well as microstructure. Based on these results, the effect of tempering on the microstructure and mechanical properties of commercial high-hardness armor steels is discussed.

The Development of Performance Test Equipment For Evaluating Endothermic Performance of Fuel Supply and Cooling System in High-Speed Vehicles (고속비행체 연료 공급 및 냉각 계통의 흡열성능 평가를 위한 성능시험 장치 개발)

  • Kim, Minsang;Choi, Won;Jun, Pilsun;Park, Jeongbae
    • Journal of Aerospace System Engineering
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    • v.13 no.4
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    • pp.43-49
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    • 2019
  • In this study, a test equipment which enables to feed endothermic fuel which is heated in the inside and outside environment of a high-speed vehicle and evaluate the heat exchangers' performance was designed and manufactured. For smooth operation of the test equipment, a test procedure that supplied endothermic fuel at high temperatures was established. The catalyst performance test was conducted based on the supply condition of the endothermic fuel and the amount of heat absorbed was analyzed. The validation of the test equipment was proved by comparing the results of catalytic reaction with the previous studies under similar reaction condition. This test equipment can be utilized in the endothermic reaction tests of catalyzed endothermic fuel under various conditions.

A Study of Loading Conditions for Developing the High-speed Bearings of the Gas-turbine Engine (가스터빈 엔진용 고속 베어링의 상세 설계를 위한 베어링 하중 조건에 관한 연구)

  • Kim, Sun Je;Kim, Yeong Ryeon
    • Journal of the Korean Society of Propulsion Engineers
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    • v.19 no.4
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    • pp.102-109
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    • 2015
  • The methodology to calculate loads on the bearings of the gas-turbine engine is presented for design of high-speed bearing. Firstly, the loads on the bearings are formulated according to the force and moment equilibrium with gyroscopic moment in three-dimensional space. Afterward, operating loading conditions of the engine are presented by applying the Joint Service Specification Guide, and magnitudes of transient and steady bearing loads are estimated based on the operating conditions. The calculated loading conditions of the bearings will be used for the essential design boundaries for the detail structural design and rig test.