• Composites Research
• /
• 제33권5호
• /
• pp.235-240
• /
• 2020

본 연구에서는 B₄C tile 삽입 B₄C_p/Al7075 하이브리드 복합재의 내충격성을 향상시키기 위하여 B₄C/Al7075 계면의 제어법을 개발하고 제어된 계면의 특성에 관하여 분석하였다. 이를 위해 B₄C 타일 표면에 B₂O₃, Ni, 그리고 Si을 각각 열산화, 무전해도금, 그리고 플라즈마 용사법을 이용하여 코팅하였다. 이후 코팅된 B₄C 타일을 액상 가압법을 이용하여 B₄C/Al7075 복합재 내부에 삽입하여 B₄C tile 삽입 B₄C_p/Al7075 하이브리드 복합재를 제작하였다. 코팅의 효과를 체계적으로 분석하기 위해 계면에너지, 접합 강도, 그리고 내충격성을 측정하였다. 모든 코팅이 계면에너지, 계면강도, 내충격성을 증가시켰으며 특히 B₂O₃ 코팅 시 내충격성이 86.8% 증가하였다. 본 연구는 차세대 경량 장갑, 방탄소재로 주목받고 있는 B₄C/Al 계열 복합재의 성능을 향상시키는 핵심적인 표면처리법을 개발, 분석한 것에 의의가 있다.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
• /
• pp.172-173
• /
• 2019

In this study, application of ultra high performance concrete(UHPC) with pre-mix binder were presented on civil, architectural and special field. The UHPC can be applied to a variety of site due to its excellent flowability, mechanical properties, impact resistance and fire resistance. It is necessary to apply the pre-mix binder to take into account the productivity and performance improvements of the UHPC.

• Journal of Mechanical Science and Technology
• /
• 제18권11호
• /
• pp.2009-2020
• /
• 2004

A parametric study of the factors controlling static and dynamic denting, as well as local stiffness, has been made on simplified panels of different sizes, curvatures, thicknesses and strengths. Analyses have been performed using the finite element method to predict dent resistance and panel stiffness. A parametric approach is used with finite element models of simplified panels. Two sizes of panels with square plan dimensions and a wide range of curvatures are analysed for several combinations of material thickness and strength, all representative of auto-motive closure panels. Analysis was performed using the implicit finite element code, LS-NIKE, and the explicit dynamic code, LS-DYNA for the static and dynamic cases, respectively. Panel dent resistance and stiffness behaviour are shown to be complex phenomena and strongly interrelated. Factors favouring improved dent resistance include increased yield strength and panel thickness. Panel stiffness also increases with thickness and with higher curvatures but decreases with size and very low curvatures. Conditions for best dynamic and static dent performance are shown to be inherently in conflict ; that is, panels with low stiffness tend to perform well under impact loading but demonstrate inferior static dent performance. Stiffer panels are prone to larger dynamic dents due to higher contact forces but exhibit good static performance through increased resistance to oil canning.

• 한국재난정보학회 논문집
• /
• 제13권2호
• /
• pp.213-220
• /
• 2017

일반적으로 유기섬유는 섬유 자체의 인장강도 및 탄성계수는 작지만, 내화성 및 내부식성이 우수하고, 콘크리트의 균열 제어 및 내충격 성능 향상에 효과적인 섬유이다. 따라서, 유기섬유는 콘크리트용 보강 섬유로서의 적용성이 매우 높은 재료이다. 본 연구에서는 폴리아미드(PA)섬유와 고강력의 폴리에스터(PET)섬유를 혼입한 하이브리드 유기섬유를 개발하였으며, 하이브리드 유기섬유를 혼입한 섬유보강 콘크리트의 휨성능 시험을 통해 하이브리드 유기섬유 보강 콘크리트의 에너지 흡수능력을 평가하고자 한다.

• 한국염색가공학회지
• /
• 제29권3호
• /
• pp.131-138
• /
• 2017

Most of high performance fabrics for the car racing protective clothing have been developed to have thermal resistance, flame retardant property, impact resistance and anti-frictional properties to protect the racer from the crucial accident. In this study, the meta-aramid fabric, which has inherent flame retardant, was coated with nanoparticles of SiC to enhance the impact resistance and anti-friction properties. Uniform coating of the nanoparticles onto the fabrics was obtained by using tape casting method. As the experimental parameters, size and content of the SiC nanoparticle were varied with the coating conditions of the fabric surface. The effects of the nanoparticle coating on the properties of meta-aramid fabric were examined with various instrumental analyses such as SEM, tensile strength and abrasion test.

• 한국자동차공학회논문집
• /
• 제13권4호
• /
• pp.129-134
• /
• 2005

There is a strong industrial demand for the development of light-weight vehicle to improve fuel efficiency and dynamic performance. The effective method of achieving the weight reduction is to use low-density materials such as aluminum and magnesium. In applying these materials to the vehicle, it is often required to join dissimilar materials such as aluminum and steel. However, conventional joining method, namely resistance spot welding cannot be used in joining dissimilar materials. Self·piercing rivet(SPR) and adhesive bonding is a good alternative to resistance spot welding. In this study, the impact test of double hat-shaped member made by resistance spot welding, SPR and adhesive bonding was performed. As a result, various parameters of crashworthiness were analyzed and evaluated. Also, the applicability of SPR and adhesive bonding as an alternative to resistance spot welding was suggested.

• 한국기계가공학회지
• /
• 제20권10호
• /
• pp.1-8
• /
• 2021

Cylinder liners used in diesel engines of combat equipment are prone to cavitation due to wet cooling. The damage caused by erosion and corrosion due to cavitation has a fatal effect on the performance and lifespan of a diesel engine. Therefore, a study was conducted to improve the durability of cylinder liners. Two surface treatment techniques were proposed: nitriding and chrome plating. It was observed that the amount of erosion on the surface of nitride-treated cylinder liners was high because the surface-treated part eroded due to its weak impact resistance against the bubble explosion generated by cavitation. In contrast, the chrome-plated cylinder liner had a lower amount of erosion among the specimens subjected to the accelerated test. These results verified that the resistance of chrome-plated liners against cavitation is high. Therefore, it can withstand the impact of bubble explosion. If the chrome plating thickness is set with reference to the KS standard, an exceptional durability of abrasion, wear resistance, and corrosion resistance can be obtained. If the thickness is set between 120~250㎛, it is expected that the durability of the cylinder liner can be improved. Although a recovery method for corroded cylinder liners is suggested, the proposed method has an inherent risk of crack generation. Therefore, further research is required to solve this problem.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제52권6호
• /
• pp.286-290
• /
• 2003

The high temperature superconducting bulk can be used as the bearing of induction motors. This paper presents the fabrication and test results of an induction motor with superconducting bearings using HTS bulks. The bearing had eight hexahedron type YBCO bulks. Height, width and thickness of the HTS bulk were 30mm, 30mm and 10mm, respectively. Single phase induction motor was used to drive the shaft made of aluminum and the rotor of a conventional induction motor. To estimate the performance of the HTS bulk magnetic bearing, no load test, load test and Impact test were carried out. Load tests were performed by using air resistance caused by the shaft-mounted thin cylinder with buckets. Impact tests by axial direction and vertical direction impact showed that the vibration of the shaft gradually decayed. The induction motor with HTS bulk magnetic bearing rotated silently and smoothly throughout the tests. According to the test results, conventional bearings can be replaced with superconducting magnetic bearings made of HTS bulks.

• 한국전산구조공학회논문집
• /
• 제29권2호
• /
• pp.161-167
• /
• 2016

이 논문에서는 벽체의 형상(평면벽체, 곡면벽체) 및 벽체에 도입된 긴장력이 충돌저항성능에 미치는 영향을 수치해석적 기법을 사용하여 평가하고자 하였다. 벽체의 곡률 및 긴장력 도입률을 변수로 총 12 케이스의 충돌해석을 수행하였으며, 충돌체로는 상용 민항기엔진의 3차원 상세모델을 사용하였다. 충돌저항성능을 평가하기 위해 관입깊이와 벽체 중앙부 후면의 최대 변위를 비교하였다. 긴장력의 도입에 의해 관입깊이는 약 60~80% 수준으로 감소하는 것으로 나타났으나, 후면 변위는 큰 차이가 나타나지 않았으며, 벽체 형상에 따른 차이는 상대적으로 크지 않은 것으로 나타났다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2009년도 추계학술대회 논문집
• /
• pp.755-761
• /
• 2009

The major advantage of transparent materials over traditional materials in noise barriers is aesthetics. The transparent panel materials such as clear plastic or glass are an ideal way of reducing or virtually eliminating the visual impact of a noise barrier. With the use of transparent materials, the drivers' view of the roadside and the sunlight penetration to the highway would not be blocked. With the use of transparent materials, the highway and barrier appear less imposing. Korean Industrial Standards for soundproof panels have been established. But, transparent soundproof panels are not included in this standards. And, some specifications provide only a few basic characteristics for transparent soundproof panels. To develop guidelines on quality criteria for transparent soundproof panel, their mechanical properties such as wind load resistance, safety under impact, and abrasion resistance were experimentally investigated.