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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korea Institute of Military Science and Technology
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Journal DOI :
The Korea Institute of Military Science and Technology
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Volume & Issues
Volume 9, Issue 4 - Dec 2006
Volume 9, Issue 3 - Sep 2006
Volume 9, Issue 2 - Jun 2006
Volume 9, Issue 1 - Mar 2006
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Heat and Flow Analysis on Cabin Room of Battle Tank
NamKoung, H.J. ; Lee, K.H. ; Park, B.H. ; Roh, K.L. ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 5~10
The heavy thermal load to battle tanks can cause electronic components' malfunction and crew to be put out of action. The thermal load is generated from Internal heat sources such as electronic devices installed in the room as well as extremely hot weather. In this study, heat and flow analysis for the cabin room of a battle tank was performed to deal with this thermal problem. This study presented the validation of simulation results in comparison with those of test, the investigation of optimal flow design for effective cooling in cabin room and finally the evaluation of thermal comforts to crew.
Characteristics and Measurement Method of the Underwater Electromagnetic Signature Emitted from a Naval Ship
Yang, Chang-Seob ; Chung, Hyun-Ju ; Shin, Seung-Je ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 11~19
The underwater electromagnetic signatures of a naval ship are mainly generated from three sources which are the permanent and induced magnetic field in the ship's hull and other ferrous components, the cathodic current electromagnetic field established by the Impressed Current Cathodic Protection(ICCP) system or the Sacrificial Anode and the stray electromagnetic fields generated by onboard equipment. These signatures can be minimized by certain design methods or installation of signature reduction equipment. In this paper, we represented the characteristic of the underwater electromagnetic signature and the signature reduction techniques for a naval ship. Also, we measured the electromagnetic field changes emitted from the real ship using the Electric and Magnetic field Measurement System(EMMS). We found that the underwater electromagnetic signature for a naval ship can be used as input or trigger signal in a surveillance system and an influence mine.
Iterative Polynomial Fitting Technique Using Polynomial Coefficients for the Nonlinear Line Array Shape Estimation
Cho, Chom Gun ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 20~25
Low frequency towed line array with high array gain and beam resolution is a long range surveillance sensor for anti-submarine warfare. The beam characteristics is however deteriorated due to the distorted line array sensor caused by low towing speed, wind, current, and towing ship maneuvering. An adaptive beamforming method is utilized in this paper to enhance the distorted line array beam performance by estimating and compensating the nonlinear array shape. A polynomial curve fitting in the least square sense is used to estimate the array shape iteratively with the distributed heading sensors data along the array. Real time array shape estimation and nonlinear array beam calculation is applied to a very long towed line array sensor system and the beam performance is evaluated and compared to the linear beamformer for the simulation and sea trial data.
Numerical analysis of acoustic field inside sonar dome by using a beam tracing method and the theory of elastic wave propagation
Han, Seung-Jin ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 26~33
A sonar dome is basically designed and installed to protect sonar array from shocks, sea wave slaps and floating matters. The acoustic wave passing through sonar dome, however, can be distorted in magnitude and phase. This paper presents a numerical method for predicting the steady-state sound pressure on the surface of transducer array in the sonar dome and typical results of sonar beam pattern affected by sonar dome. A beam tracing model with phase information and a multi-layered elastic boundary model are involved. A full three-dimensional sonar dome is modeled as a GRP acoustic window, a rubber coated steel baffle and a rubber coated steel hull. A transducer array is modeled as thick steel cylinder. There are some assumptions such as incidence of plane wave, specular reflection on boundary and directionality of transducer element.
Operation of Night Vision Goggle for Aircraft
Kwon, Jong-Kwang ; Kim, Whan-Woo ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 34~41
This paper describes the general considerations and operational applications of aircraft night vision goggle(NVG). The operators should recognize the NVG characteristics, natural night light sources and interoperability between them. And they have to keep attention to the method to take steps to avoid misperceptions, illusions during flight, and the negative impact on the effectiveness and safety of the mission. The considerations based on the interoperability between NVG and night operation suggest the evaluation items of NVG field test and flight test.
An Study on the Erosion Characteristics of Tube CN98
Kim, Jae-Kab ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 42~52
Tube erosion can be defined as a phenomenon for an increment of bore diameter, a declination of accuracy and utility of tube by firing. This study introduces the characteristics of tube life for the 155 mm K9 SHP Using a tube history book with bore measurement data and firing data of standard charge, this study analyzed the EFC vs Tube life and EFC with heat transfer effect formula as a consideration of continuous firing vs tube life. The results were compared with Firing Table(FT 155-K9-1) after the analysis. Also, this study suggests that CN98 tube can be rifled as 1000 EFC through the severe condition with continuous firing.
Reliability Analysis Procedures for Repairable Systems and Related Case Studies
Lee, Sung-Hwan ; Yum, Bong-Jin ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 51~59
The purpose of this paper is to present reliability analysis procedures for repairable systems and apply the procedures for assessing the reliabilities of two subsystems of a specific group of military equipment based on field failure data. The mean cumulative function, M(t), the average repair rate, ARR(t), and analytic test methods are used to determine whether a failure process follows a renewal or non-renewal process. For subsystem A, the failure process turns out to follow a homogeneous Poisson process, and subsequently, its mean time between failures, availability, and the necessary number of spares are estimated. For subsystem B, the corresponding M(t) plot shows an increasing trend, indicating that its failure process follows a non-renewal process. Therefore, its M(t) is modeled as a power function of t, and a preventive maintenance policy is proposed based on the annual mean repair cost.
A Study on Improvement of Defense R & D Program by PMB
Choi, Seok-Cheol ; Bae, Yun-Ho ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 60~69
The PMB(performance measurement baseline) is the total time-phased budget plan against which program performance is measured. Additionally it is the schedule for expenditure of the resources allocated to accomplish program scope and schedule objectives, and is formed by the budget assigned. In this paper, we suggest an improvement of the R & D(research and development) program for defense acquisition by using the PMB and an application of the IBR(integrated baseline review) to review the PMB for project manager of the defense agency.
A Study on the Prediction of Grain Size Distribution in Hot Forging of Waspaloy Turbine Disc
Yeom, Jong-Taek ; Lee, Chong-Soo ; Kim, Jeoung-Han ; Lee, Dong-Geun ; Park, Nho-Kwang ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 70~76
The microstructure evolution during a hot forging of Waspaloy was investigated using the recrystallization model and FEM simulation. In order to obtain an uniform microstructure, hot forging was carried out by two step. The change of grain size during hot forging has a deep connection with dynamic recrystallization behavior. Avrami-type constitutive equation for the dynamic recrystallization was implemented into an user subroutine of 2D FE simulator. The evolution of grain structure in the two-step forging of Waspaloy was simulated using the 2D FEM user-subroutine. The detailed variation of microstructures due to dynamic recrystallization could effectively be predicted at various locations in a forged pancake.
A Study on the Reaction Time Reduction Method for the ECM System by using the Feed-back Tracking-gate Filtering
Kim, So-Yeon ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 77~86
Usually, a tracking-gate of the tracker is used to track the target radar signal in the active ECM system. In this paper, we propose the feed-back tracking-gate filtering method. The designed method applies a tracking-gate of the tacker to the ECM system's receiver as a rejection or pass filter selected by the receiver's purpose, and the specific target signals can be passed or rejected though this tracking-gate filter. Thus, the number of input signals within the receiver's search band is minimized owing to this filter except the target signals. In conclusion, the EW equipment's reaction time can be reduced and the error value about the target signals can be lower than the previous methods'.
Estimation of Ground Clutter Reflectivity based on the CFT(Captive Flight Test)
Son, Chang-Hee ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 87~95
The performance of a microwave missile seeker and radar operating in an air-to-air look-down mode is strongly influenced by the presence of ground clutter In order to correctly account for the effects of ground clutter, it is required to develop a model capable of representing clutter characteristics as a function of range and/or frequency. In this paper, a program to estimate the clutter reflectivity for various ground conditions is developed, using the actually measured data and the data available from open literatures. In addition, clutter characteristics measured for various ground conditions such as sea, agricultural area, urban city and industrial area through the captive flight tests are presented.
A Research on the Beam Pattern Control of Adaptive Array Antenna for GPS Receiver
Ahn, Seung-Gwan ; Lee, Sang-Jeong ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 96~102
In this paper, the design, construction and basic characteristics of an electronically adaptive array antenna for the GPS receiver is described. The susceptibility of the GPS signals to the interference is of concern to the GPS user community. Because of the low received power of the GPS signals, outages can easily occur due to the unintentional interference and the easily obtainable low cost GPS jammer denying access to the GPS signals. We propose a technique of the adaptive array antenna that detects the GPS interference sources and controls the null beam pattern only toward the jamming sources to acquire GPS navigation data after acquisition and tracking of the GPS signals.
Design and Fabrication of a W-band Total Power Radiometer
Jung, Myung-Suk ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 103~110
We present a W-band radiometer to detect the metal targets on the ground environment. The type of the designed radiometer is the total power radiometer(TPR) for the simple configuration. The front end of the TPR consists of only the Mixer and LO for miniaturizing the system. Because the radiometer system does not use the low noise amplifier, we use matching circuits and a diode detector configured as a voltage doubler to compensate the degradation of sensitivity. We solve the temperature variation problems by filtering the reference voltages of the radiometer output signals. Through some experiments, we have verified that the designed radiometer system has good performances in detecting metal targets lying at several hundred meters.
High Resolution Electronic Processor Design for Thermal Imager with 320x240 Staring Array Infrared Detector
Hong, Seok-Min ; Yu, Wee-Kyung ; Yoon, Eun-Suk ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 111~117
This paper describes the design principles and methods of electronic processor for thermal imager with 320
240 staring array infrared detector. For the detector's nonuniformity correction and excellent image quality, we have designed the multi-point correction method using the defocusing technique of the optics. And to enhance the image of low contrast and improve the detection capability, the new technique of histogram processing has been designed. Through these image processing techniques, we have developed the high quality thermal imager and acquired a satisfactory thermal image. The result of MRTD(Minimum Resolvable Temperature Difference) is
Target event analysis using complex signal of instrumentation radar
Hwang, Gyu-Hwan ; Seo, Il-Hwan ; Ye, Sung-Hyuck ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 118~126
As weapon systems are becoming advanced and intelligent, they are designed to have such events like ejecting sub-munitions. So it is continually requested to measure the event time and position exactly. We can measure the event time and position by analyzing the complex signal of the instrumentation radar in the time domain and can also obtain the spin rate of the target by analyzing the complex signal in the frequency domain.
Effects of the Sintered Wick Characteristics on the Heat Transport Limitations of the Heat Pipes
Kim, Keun-Bae ; Kim, Yoo ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 127~135
Experimental studies of the cylindrical sintered-copper wick heat pipes were carried out to investigate the capillary heat transfer characteristics. Six models of the sintered-copper wick heat pipes were manufactured and tested to evaluate the heat transport limitations and the thermal characteristics. Also the performance of the heat pipes was analyzed theoretically and compared with the test results. The heat pipe models are divided into two sintered-wick groups and the nominal particle sizes are
(wick #1) and
(wick #2) respectively The experimental results showed that, the porosity of wick #1 was higher than that of wick #2, and also the wick #1 was generally superior than the wick #2 for the heat transport capability. The maximum heat transport rates were increased as the wick thicknesses and the vapor temperatures were increased.
A Damped Sinusoidal Electromagnetic Pulse Generator using a Charged Line
Ryu, Ji-Heon ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 136~142
A damped sinusoidal electromagnetic pulse generator was designed, fabricated and tested. The pulse generator consisted of an oscillator(a spark gap switch and an initially charged low impedance line) and a high impedance antenna. This generator was capable of producing damped sinusoidal pulses at closure of the spark gap switch. A Marx generator was employed to supply the Pulse generator with high voltage pulses. While the pulse generator was provided with the high voltage pulses of 200kV from the Marx generator, its output power was maximized by controlling the pressure of the gas contained in the spark gap switch. The output power of the damped sinusoidal electromagnetic pulse oscillator was 1.3GW and the amplitude of electric field radiated from the pulse generator was 4kV/m at the range of 25m.
Aerodynamic Analysis of Lateral Jet Controlled Missile Using CfDS Code
Kim, Jae-Gwan ; Lee, Jeong-Il ; Kim, Chong-Am ; Hong, Seung-Gyu ; Lee, Kwang-Seop ; Ahn, Chang-Soo ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 143~151
This paper investigates effects of reaction control jet on the aerodynamic performance of generic interceptor missile operating at supersonic flight condition. Parallelized CFDS code is used as a viscous flow solver. The generic interceptor missile configuration composed of a long and slender body and fixed tail fins. The behavior of normal force, axial force and pitching moment characteristics at altitude conditions corresponding to 10 km is studied according to the given control jet conditions, different angle of attacks based on the analysis of aerodynamic characteristics.
A Study of Local Preconditioning Method for Compressible Low Speed Flows
Ryu, Se-Hyun ; Lee, Seung-Soo ; Kim, Beom-Soo ;
Journal of the Korea Institute of Military Science and Technology, volume 9, issue 2, 2006, Pages 152~160
Time marching methods are well-suited for high speed compressible flow computations. However, it is well known that the time marching methods suffer a slow down in convergence due to disparity in Eigenvalues. A local preconditioning method is one of numerical methods to enhance convergence characteristics of low mach number flows by modifying Eigenvalues of the governing equations. In this paper, the local preconditioning method of Weiss is applied to a 2 dimensional Navier-Stokes code and the efficiency of the preconditioning method is shown through a number of computational examples.