• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.3
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• pp.339-345
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• 2016

This paper is concerned with the numerical simulation result of pressure propagation to the main charge by warhead penetration into concrete targets. In this study, we developed on-line pressure measurement method in the main charge during warhead penetration. Using the on-line pressure measurement method, we successfully recorded the pressure-time history in the main charge during the field penetration test. Then we compared result of numerical simulations with test data and found that the simulation results are in good agreement with the test results. Finally, through the numerical calculations it is concluded that the installation of liner is effective in reducing pressure level produced in the main charge.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.2
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• pp.133-140
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• 2019

In this paper, the penetration process of Shaped charge jet(SCJ) was simulated through finite element analysis to obtain physical quantities such as jet incidence velocity, penetration rate, and penetration increment. As a result of applying these physical quantities to the hydrodynamic theory, it was confirmed that the penetration efficiency of the jet with a high incident velocity is higher than that of the following slow jet. This efficiency decreased sharply when the jet was slower than the hydrodynamic limit(HL). On the other hand, the comparison of penetration increment and jet consumption over time showed that the length extension effect should be considered for SCJ's theoretical penetration analysis.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.5
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• pp.566-573
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• 2015

The most important factor for the penetration performance of shaped charge is the liner design. By designing the liner to have properties of both high jet tip velocity and long jet break-up time, the better penetration performance could be acquired. Usually it is very difficult to satisfy above two conditions simultaneously. In this study, the liner with the shape of ogive was developed to have relatively larger jet mass compared to the conventional trumpet liner. The designed shaped charge showed jet properties with high jet tip velocity and long jet break-up time by using ogive liner and wave shaper. A commercially available hydro-dynamic code AUTODYN-2D was used for numerical analysis of jet formation. The flash X-ray test and the static penetration test were conducted to verify the results of numerical analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.6
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• pp.397-404
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• 2019

Linear Shaped Charge (LSC) that is widely used as separation system in aerospace system has to charge lots of explosives due to lack of uniformity. In addition, it is hard to optimize shape of liner and explosives because of manufacturing process. In order to overcome aforementioned drawbacks, Precision Linear Shaped Charge (PLSC) is currently under development. PLSC is made in two steps: prepare liner independently and charge explosive uniformly. In this study, PLSC is designed to have proper amount of explosives and penetration test of PLSC with different stand-off distance from liner to target is conducted to confirm penetration performance. Based on the penetration test results of PLSC, the numerical analysis method using AUTODYN is established and verified. Penetration mechanism and characteristics of PLSC is analyzed from the numerical and experimental results.

• The Korean Journal of Ceramics
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• v.5 no.3
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• pp.270-277
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• 1999

The ballistic capability of an alumina-rich oxide armor ceramic against a shaped jet was characterized as a function of penetration depth in a layered target structure. The penetration resistance of the ceramic, based upon the determination of penetration velocity, was not equally realized throughout the depth of penetration. It was abnormally low at an early stage of penetration, followed by a sudden increase to reach ~16GPa thereafter. There was no apparent change in such a profile with respect to the lateral size of the specimen. Based upon 2-D flash x-ray radiography and 3-D Hull code simulation, the feasibility of forming a pressure-induced predamnaged zone in front of the jet tip was speculated to foster an increased penetration velocity in the initial stage penetration, resulting in the diminished penetration resistance. The disappearance of such a predamaged zone with penetration was interpreted to restore the resistance of the ceramic in the later penetration stage.

• Biomolecules & Therapeutics
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• v.19 no.2
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• pp.231-236
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• 2011

The aim of this study was to investigate the effect of charge carrier lipid on the skin penetration, retention, and hair growth of topically applied finasteride-containing liposomes. Finasteride-containing liposomes were prepared by traditional thin film hydration method using Phospholipon$^{(R)}$ 85 G and cholesterol with or without charge carrier lipid (1,2 dimyristoyl-sn-glycero-3-phosphate or 1,2-dioleoyl-trimethylammonium-propane for anionic and cationic charge, respectively). Freshly prepared finasteride-containing liposome suspension was applied on the hairless mouse skin, and skin penetration and retention were measured using Keshary-Chien diffusion cell. Non-liposomal formulation (ethanol 10% solution containing 0.5 mg/ml of FNS) was also used as a control. The amount of finasteride in the diffusion cell and mouse skin was measured by HPLC. The hair growth was evaluated using depilated male C57BL/6N mice. Mean particle size of all finasteride-containing liposomes was less than a micron, and polydispersity index revealed size homogeneity. Skin penetration and retention studies showed that significantly less amount of finasteride was penetrated when applied as anionic liposome while more amount of the drug was retained. Specifically, in liposome prepared with 10% anionic charge carrier lipid, penetration was 12.99 ${\mu}g/cm^2$ while retention was 79.23 ${\mu}g/cm^2$ after 24 h of application. In hair growth study, finasteride-containing anionic liposomes showed moderate efficacy, but the efficacy was not found when applied as cationic liposomes. In conclusion, topical application of finasteride using anionic liposome formulation appears to be useful option for the treatment of androgenetic alopecia to avoid systemic side effects of the drug.

• Explosives and Blasting
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• v.34 no.4
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• pp.1-9
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• 2016

For underwater steel structure, cut that underwater shaped charge device that combines a spring hose, which is an external device of pressure resistance and flexibility with flexible shaped charge, was invented. As a basic experiment for an optimum condition design, an penetration performance was compared by external device shape. To evaluate the result of an experiment, image analysis was carried out after obtaining the model by using the liquid rubber for the penetrated steel plate. To simulate the penetrating process of shaped charge, the AUTODYN program has been used. As a result of analysis, while the average penetration depth of circular and square shaped external devices were similar, the penetration quality was more uniform in the case of circle. In addition, water infiltration occurred in square case, displacement and strain rate according to the increase of the water pressure were measured high.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.3
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• pp.275-284
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• 2022

Linear Shaped Charge(LSC) is widely used as a separation system in the field of weapon system. However, there are some disadvantages that are charging lots of explosives due to lack of uniformity and having difficulties of the design of liner and explosives because of manufacturing process. In order to solve these problems, Precision Linear Shaped Charge(PLSC) that can design a liner independently and charge explosives uniformly has been developed. In this study, PLSC was designed to have a proper liner shape and amount of explosives, and the penetration test of PLSC with different stand-off distance from liner to target was conducted. On the basis of the penetration test results of PLSC, the numerical analysis method using AUTODYN was established and verified. The penetrative mechanism and characteristics of PLSC with targets of different materials was analyzed from experimental and numerical results.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.5
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• pp.574-581
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• 2015

In this paper, the effect of high voltage current pulse against shaped charge jet was analyzed through the visualization of jet behavior using flash X-ray and comparison of depth of penetration(DOP) into RHA(Rolled Homogeneous Armor) witness plates. The behavior of jet particles has been acquired using a flash X-ray equipment when current pulse was applied into the metal jet of a shaped charge(SC) warhead. Typical results such as jet breakup and radial jet dispersion, which are due to electromagnetic pressure by current pulse, have been obtained. Dozens of penetration experiments using a shaped charge with 55 mm diameter were performed according to various combinations of major parametric variables such as electrode spacing, standoff distance from SC warhead to electrode, and charge voltage. Subsequently, interrelations between major parametric variables and DOPs into RHA were analyzed.

• Journal of the Korea Society for Simulation
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• v.31 no.3
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• pp.11-21
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• 2022

Two methods for analyzing interaction between shaped charge jets and targets are taken in AVEAM-MT (ADD Vulnerability and Effectiveness Assessment Model for Materiel Target), which is a model for vulnerability analysis of materiel targets and being developed by ADD. One is an empirical method improved from the Fireman-Pugh technique for rapid penetration calculation into target components. The other is ADD-TSC(ADD Tandem Shaped Charge), which is a physics-based model extended to be applicable for shaped charge jets from the Walker-Anderson penetration model for higher fidelity analysis. In this paper, the two methods are briefly described, and the empirical technique is compared to the physics-based model in the prediction of residual penetration capacity. The latter is also compared to experimental results found in literature in predicting penetration capacity. These comparisons show that both methods can be used for fast calculations or higher fidelity calculations in vulnerability analysis models like AVEAM-MT which is required to perform a considerable amount of iterative simulation for damage analysis.