• 한국CDE학회논문집
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• 제20권3호
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• pp.238-245
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• 2015

Vulnerability assessment is a process to calculate the damage degree of a combat vehicle when the combat vehicle is attacked by an enemy. When the vehicle is hit, it is necessary to analyze the shot line to calculate which components are damaged and judge whether the armor of the vehicle is penetrated by enemy's warhead. To analyze the shot line efficiently, this paper presents the target modeling and the shot line analysis system to assess vulnerability of the ground combat vehicle. This system is easily able to do several functions: 1) the program reads STL files converted from CAD model which is designed by commercial CAD software. 2) It calculates the intersection between triangle of STL mesh and the shot line, and check if the components of the model are penetrated. 3) This program can visualize the results using OpenGL. The vulnerability assessment using the shot line analysis can be used to model the armor of the combat vehicle and arrange the inner components effectively in the early stage of development of the combat vehicle.

• Computers and Concrete
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• 제5권6호
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• pp.509-524
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• 2008

Containment structures not only are leak-tight barriers, but also may be subjected to impacts caused by tornado-generated projectiles, aircraft crashes or the fragments of missile warhead. This paper presents the results of an experimental study of the impact resistance of steel fiber-reinforced concrete against 45 g projectiles at velocity around 2500 m/s. An explosively formed projectile (EFP) was designed to generate an equivalent missile fragment. The formation and velocity of EFP are measured by flash x-ray. A switch made of double-layered thin copper sheets controlled the exposure time of each flash x-ray. The influence of the fiber volume fraction on the crater diameter of concrete slab and the residual velocity of the projectile were studied. The residual velocity of the projectile decreased as the fiber volume fractions increased. In this work, the residual velocity of the projectile was to 44% that of plain concrete when the fiber volume fraction exceeded 1.5%. Based on the present finding, steel fiber reinforced concrete with the fiber volume fraction exceeding 1.5% appear to be more efficient in protection against high velocity fragment impact.

• 한국군사과학기술학회지
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• 제20권2호
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• pp.217-224
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• 2017

This study proposes an evaluation method for time delay function(TDF) of Point Detonation(PD) fuse using underwater explosion and water entry phenomena. Until now, nothing but the naked eyes of an observer or video images have been used to determine whether the TDF of PD fuze is operated or not. The observer has verified the performance of TDF by analysing the shape of the plume formed by underwater explosion. However, it is very difficult to evaluate the TDF of PD fuse by these conventional methods. In order to overcome this issue, we propose a method using underwater sound signal emitted from the underwater explosion of high explosive charge. The result shows that the measured sound signal is in accord with the physical phenomena of water entry of warhead as well as underwater explosion. Also, from the hypothesis test of bubble period, difference on underwater sound analysis between dud event and delay one is proved.

• 한국CDE학회논문집
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• 제18권5호
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• pp.367-373
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• 2013

In this study, the penetration characteristic from the cubic and cylindrical penetrator consisting of tungsten material with the velocity of 2,300 m/s is evaluated and the penetration possibility into the target is confirmed. The design of shape and size of penetrator is directly related to space and weight of the warhead. AUTODYN-3D simulation is used to study the penetration effect of penetrator. The purpose of numerical analysis is to verify the penetration characteristic with various L/D penetrator. The penetration performance of penetrator with identical weight due to the shape is also confirmed. The cylindrical and cubic penetrator has enough penetration energy on constant target body. Because the possibility of 2'nd penetration is important factor after 1'st penetration into target body, residual velocity of residual mass must be existed as much as possible. As geometrical shape ratio increases, penetration performance is confirmed to improve.

• 한국군사과학기술학회지
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• 제7권3호
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• pp.129-139
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• 2004

DXD-19 is a flexible sheet explosive, which is a new polymer-bonded explosives(PBX's). DXD-19 is relatively insensitive and can be extruded into various configurations to be applied to munitions. A typical application includes multi-point initiation for the warhead, cutting/severance devices and transfer lines. The DXD-19 composition employs a binder system derived from the thermoplastic elastomer(HyTemp 4454) containing $5\%$ OH terminated with isocyanate curable for increasing mechanical properties. The use of an elastomer CAB increases its mechanical properties and the use of an energetic plasticizer BDNPF/BDNPA(F/A) improves the process ability as well as energy contents. The composition of the extruded DXD-19 formulation is formed $\%$ weight of $PETN/HyTemp/ATEC/(F/A)/CAB=72\~73/12\~13/6\~7/6\~7/1\~2$. Our safety tests of DXD-19 shows Insensitivity to an impact test and friction test, good thermal stability and excellent mechanical properties.

• 한국분말재료학회지
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• 제27권5호
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• pp.373-380
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• 2020

The purpose of this study is to investigate the densification behavior and the corresponding microstructural evolution of tantalum and tantalum-tungsten alloy powders for explosively formed liners. The inherent inhomogeneous microstructures of tantalum manufactured by an ingot metallurgy might degrade the capability of the warhead. Therefore, to overcome such drawbacks, powder metallurgy was incorporated into the near-net shape process in this study. Spark plasma-sintered tantalum and its alloys with finer particle sizes exhibited higher densities and lower grain sizes. However, they were contaminated from the graphite mold during sintering. Higher compaction pressures in die and isostatic compaction techniques also enhanced the sinterability of the tantalum powders; however, a full densification could not be achieved. On the other hand, the powders exhibited full densification after being subjected to hot isostatic pressing over two times. Consequently, it was found that the hot isostatic-pressed tantalum might exhibit a lower grain size and a higher density as compared to those obtained in previous studies.

• 한국세라믹학회지
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• 제43권10호
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• pp.646-652
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• 2006

Several oxynitride glasses were fabricated by means of adding $Si_3N_4$ powders as nitrogen source to Ca-Al-Si-O-N (CAS) and Mg-Al-Si-O-N (MAS) glass powders, and heat-treated in graphite crucible at 1600$^{\circ}C$ for 1 h. The physical and mechanical properties as well as impact resistance were generally increased and compared with each other. The impact resistance properties of those manufactured glasses were evaluated by DOP (depth of penetration) method which is a way to analyze armor materials. There were two means to be used herein; the copper jet impacted at hyper velocity by exploding K2l5 warhead and tungsten heavy alloy (WHA) impact bar at high velocity by firing in 30 mm solid propellent gun. The impact resistance properties against copper jet were increased and then decreased with increasing nitrogen content, while those against WHA bar were not changed apparently with nitrogen content.

• Structural Engineering and Mechanics
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• 제38권5호
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• pp.633-649
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• 2011

The paper presents a study aimed at understanding some characteristics of an interior explosion within a room with limited or no venting. The explosion may occur in ammunition storage or result from a terrorist action or from a warhead that had penetrated into this room. The study includes numerical simulations of the problem and analytical derivations. Different types of analysis (1-D, 2-D and 3-D analysis) were performed for a room with rigid walls and the results were analyzed. For the 3D problem the effect of the charge size and its location within the room was investigated and a new insight regarding the pressure distribution on the interior wall as function of these parameters has been gained. The numerical analyses were carried out using the Eulerian multi-material approach. Further, an approximate analytical formula to predict the residual internal pressure was developed. The formula is based on the conservation law of total energy and its implementation yields very good agreement with the results obtained numerically using the complete statement of the problem for a wide range of explosive weights and room sizes that is expressed through a non-dimensional parameter. This new formula is superior to existing literature recommendations and compares considerably better with the above numerical results.

• 한국전자파학회논문지
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• 제23권7호
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• pp.815-821
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• 2012

CW 도플러 레이더는 움직이는 물체의 속도에 비례하는 도플러 주파수 편이를 검출함으로써 속도를 계측한다. 도플러 주파수 편이를 검출하기 위해서 시간영역에서 획득한 수신 신호를 주파수 영역으로 변환하기 위한 FFT(Fast Fourier Transform)를 수행한다. 이때 FFT 개수에 의해 도플러 레이더의 시각 분해능이 달라진다. 또한, FFT 개수는 수신 신호의 신호 대 잡음비에도 영향을 미치므로, 결국 시선 속도의 정확도와도 관련 있다. 따라서 본 논문에서는 FFT 개수에 따라 달라지는 시각 분해능과 시선 속도 정확도의 관계를 제시하였다.

• 한국국방경영분석학회지
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• 제28권2호
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• pp.70-84
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• 2002

This paper deals with the attrition rate of major facility such as a particular building that is one of the most important target in the war time. In order to estimate the attrition rate, we use JAWS, WinJMEM which are programed by JTCG/ME of AMSAA and spreadsheet package which is able to assist the limitation of those programs and calculate all the procedure of this computation. This method uses the effectiveness index(El) which indicates the numerical measure of the effectiveness of a given weapon of a given target. The range error probable(REP) and the deflection error probable(DEP) in the ground plane also should be used. Those mean the measure of delivery accuracy of the weapon system. In this paper, it is improved that the El can be obtained from the regression analysis using the weight of the warhead explosive as the independent variable. It implies that we are able to obtain the El and the conditional probability of damage of the enemy weapon. After that, the single-sortie probability of damage can be computed using WinJMEM or another assistant program such as the spreadsheet package which shows the result immediately.