• Bulletin of the Korean Chemical Society
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• v.24 no.4
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• pp.473-478
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• 2003

3-Amino-2-hydroxy-4(3H)-quinazolinone (3) was prepared via condensation of 1 with hydrazine hydrate. Treatment of 3 with appropriate acid in $POCl_3$, ethyl chloroacetate and activated olefinic compounds in DMF yielded the corresponding 3-(substituted)amino-2-hydroxy-4(3H)-quinazolinones 4, 5 and 6. The electron impact ionization mass spectra of compounds 3 and 4 show a weak molecular ion peak and a base peak of m/z 146 resulting from a cleavage fragmentation. The compounds 5 and 6 give a characteristic fragmentation pattern with a very stable fragment of benzopyrazolone (m/z 132).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.29-29
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• 1998

실전 배치되어 운용 중인 무기체계는 여러 형태의 사고 위험이 항상 존재한다 이중에서도 특히 항공기나 함정에서 발생하는 사고는 그 피해가 막대하게 커질 수도 있어 항공기나 함정 자체에 위협을 줄 수도 있다. 이러한 사고위험으로부터 인적, 물적 자원을 보호하기 위하여 둔감탄약(Insensitive Munitions)에 대한 인식이 높아지고 있으며, 아울러 이러한 무기 체계를 효과적으로 시험 평가하는 규격들이 검토되기 시작하여 1991년에 "Hazards Assesment Tests for Non-Nuclear Ordnance, DoD-STD-2105"를 기초로 한 MIL-STD-2105B가 채택되었다. 본 논문에서는 MIL-STD-2105B의 해석과 그에 따른 둔감탄약 시험에 포함되는 Bullet Impact Test, Fast Cookoff Test, Slow Cookoff Test, Fragment Impact Test, Sympathetic Detonation Test 등의 시험들의 세부적인 시험방법과 그 결과에 대한 판정 기준을 서술하였다. 또한 유도무기의 추진기관을 모델로 하여 둔감탄약 시험의 기준을 제시하였고 이 시험을 통과하기 위하여 향후 연구, 개발하여야 할 분야를 서술하였다.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.3
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• pp.378-386
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• 2014

In this paper, safety evaluation method simulating battlefield environment was studied to verify military operability of commercial lithium secondary battery. Based on the MIL-STD-2105D and STANAG standards, safety tests of lithium secondary battery module were conducted, such as bullet impact, fragment impact, fast cook-off and slow cook-off. All results satisfied the safety evaluation criteria, founded on military standard. It suggests that the lithium secondary module has high potential to be applied in a military power source. The safety evaluation methods developed in this paper can be valuable to propose the new military standards for commercial lithium secondary batteries.

• Analytical Science and Technology
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• v.9 no.1
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• pp.1-12
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• 1996

The thermally labile compounds with hydroxyl group generate the [${MNH_4}^+$] ion, [$MH^+$] and [$MH^+-OH$] ion by ion-molecule reaction in LC/TSP/MS. But these ions create the trouble in the estimation of molecular weight of an unknown compound because the margin of [${MNH_4}^+$] ion and [$MH^+$] ion is same to that of [$MH^+$] ion and [$MH^+-OH$] ion. If it is compensated for the results by using of the $CF_3COOD+NH_4OH$ LC eluent, the molecular weight of analyte will be able to be confirmed. And this study was tried to recognize whether the fragment ions of thermally labile compound are generated by electron impact or by thermal degradation in ion source.

• The Journal of the Korea Contents Association
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• v.20 no.11
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• pp.559-568
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• 2020

The purpose of this study was to conduct a survey and analysis of 249 children of the Fragment Love Sharing Society to find out the impact of the association program on children. Correlation analysis was conducted using the SPSS Statistics 23 program to confirm the relationship between scholarship students and scholarship management institutions, and regression analysis was conducted to confirm the impact of the relationship between scholarship students and the scholarship management institution. According to the analysis, the higher the satisfaction level of scholarships, the higher the level of career proficiency and yesterday's happiness, and the more satisfied the child is with the benefits of the crumb scholarship, the higher the sense of self-respect, career maturity, and yesterday's happiness. Based on these findings, support measures were discussed for children with ties.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.3
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• pp.221-226
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• 2010

The failure of a Kevlar29/Phenolic composite plate under high-velocity impact from an fragment simulation projectile was investigated using the nonlinear explicit finite element code, LS-DYNA. The composite laminate and the impactor were idealized by solid elements, and the interface between the laminas was modeled as a tiebreak type in LS-DYNA. The interaction between the impactor and laminate was simulated using a surface-to-surface eroding contact algorithm. When the stress level meets the given failure criteria, the layer in the element is eroded. Numerical results were verified through existing test results and showed good agreement.

• Composites Research
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• v.22 no.2
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• pp.18-23
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• 2009

Failure of Kevlar29/Phenolic composite plate under high velocity impact of FSP(Fragment Simulation Projectile) is investigated using a non-linear explicit finite element code, LS-DYNA. Composite laminate and impactor are idealized by solid element and interface between laminas are modeled by tied-break element in LS-DYNA. Interaction between impactor and laminate is simulated face-to-face eroding contact algorithm. When the stress level meets a failure criteria, the layer in the element is eroded. Numerical results are verified by existing test results.

• Journal of the Korea Institute of Building Construction
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• v.13 no.5
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• pp.465-473
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• 2013

Concrete is an outstanding material in terms of its impact and blast resistance performance. However, there a limitation of concrete is its risk of collapse due to the brittle failure and spalling. Increasing the thickness of members was used as a method to enhance the protective performance of concrete, despite the resulting inefficient space. To solve this problem, different types of fiber reinforced concrete were developed. Recently, another type of fiber reinforced concrete is also being developed and applied as a material that offers protection against impacts and blasts by increasing the flexural toughness of concrete. In this study, the test was conducted to evaluate the impact resistance performance of fiber reinforced concrete and mortar according to impact of high-velocity projectile. A concrete T-wall was also tested to evaluate its protective performance from fragment by 155mm-thick artillery shell. The test results revealed that improving flexural strength through fiber reinforcement inhibited cracks and spalling of rear, and spalling of front by high-velocity impact. As such, it is expected to improve the protective performance of the T-wall and reduce the thickness of the member.

• Composites Research
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• v.26 no.6
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• pp.349-354
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• 2013

In this paper, we conducted high velocity impact test for Carbon/Epoxy composite laminates and proposed advanced method for predicting the absorbed energy of composite laminates. During high-velocity impact test, we discovered loss of projectile mass macroscopically using high speed camera, thus we calculated the absorbed energy of composite laminates by taking loss of projectile mass into account. We proposed a model for predicting the absorbed energy of composite laminates subjected to high-velocity impact, the absorbed energy was classified into static energy and dynamic energy. The static energy was calculated by the quasi-static perforation equation that is related to the fiber breakage and static elastic energy. The dynamic energy can be divided by the kinetic energy of deformed specimen and fragment mass. Finally, the predicted absorbed energy considering loss of projectile mass was compared with experimental results.

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.157-167
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• 2015

Cement composites subjected to high-velocity projectile shows local failure and it can be suppressed by improvement of flexural toughness with reinforcement of fiber. Therefore, researches on impact resistance performance of cement composites are in progress and a number of types of fiber reinforcement are being developed. Since bonding properties of fiber with matrix, specific surface area and numbers of fiber are different by fiber reinforcement type, mechanical properties of fiber reinforced cement composites and improvement of impact resistance performance need to be considered. In this study, improvement of flexural toughness and failure reduction effect by impact of high-velocity projectile have been evaluated according to fiber type by mixing steel fiber, polyamide, nylon and polyethylene which are have different shape and mechanical properties. As results, flexural toughness was improved by redistribution of stress and crack prevention with bridge effect of reinforced fibers, and scabbing by high-velocity impact was suppressed. Since it is possible to decrease scabbing limit thickness from impact energy, thickness can be thinner when it is applied to protection. Scabbing of steel fiber reinforced cement composites was occurred and it was observed that desquamation of partial fragment was suppressed by adhesion between fiber and matrix. Scabbing by high-velocity impact of synthetic fiber reinforced cement composites was decreased by microcrack, impact wave neutralization and energy dispersion with a large number of fibers.