• 대한기계학회논문집
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• 제12권1호
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• pp.19-27
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• 1988

본 연구에서는 화학성분, 마르텐사이트 체적율, 연결도, 모상위경 및 제2상의 형태를 되도록 일정하게 하고, 제1상과 제2상의 경도비만을 변화시켰을 때의 충격降伏荷重 및 충격최대하중의 거동, 충격속도가 하중작용시간에 미치는 영향, 흡수에너지 및 延性-胞性거동 등을 고찰하였다.

• 한국표면공학회지
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• 제35권6호
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• pp.408-414
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• 2002

TiN and TiAlN coating layer were deposited on WC-Co steel substrates by an arc ion plating(AIP) technique. The crystallinity and morphology for the deposited coating layers were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The impact behaviors of the deposited TiN and TiAlN coating layer were investigated with a ball-on-plate impact tester. Beyond $10^2$ impact cycle, TiAlN coating layer showed superior impact wear resistance compared to TiN coating layer. On the other hand, both TiN and TiAlN coating layers started to be partially failed between $10^2$ and $10^3$ impact cycle. Above $10^3$ impact cycle, TiN and TiAlN coating layers showed similar impact behavior because of the substrate effect.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.857-860
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• 2006

In the present study, the method and procedure for analysis of impact damage behavior for concrete under penetration and perforation of projectile is investigated. Conservation law, equation of motion, initial and boundary conditions, and FEM formulation are introduced and derived respectively. Specially, the constitutive equation which rate-dependent damage combined with rate-dependent plasticity within the appropriate framework of theory of thermodynamics is examined. This paper aimed at the review with respect to impact damage models for concrete to develop that model. This paper is a basis research for the development of impact damage model for concrete.

• 한국콘텐츠학회논문지
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• 제19권3호
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• pp.635-648
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• 2019

많은 기업가정신에 관한 연구들이 자기효능감, 셀프리더쉽과 같은 긍정적인 특성을 중점으로 진행되었다. 하지만 최근에 해외에서는 ADHD 성향(주의력결핍성향)과 같이 부정적인 특성이 기업가정신에 미치는 영향에 대한 연구들이 진행되고 있다. 본 연구는 ADHD 성향이 기업가지향성과 창업의도에 미치는 영향을 살펴보았다. 이와 더불어 본 연구는 선행연구들이 주로 기회발견과 기업가적 기민성에 초점을 둔 특성인 스키마가 기업가지향성과 창업의도에 미치는 영향을 살펴보았다. 청년 세대를 대상으로 리서치 회사를 통해서 온라인 조사를 진행한 결과 ADHD 성향은 위험감수성과 혁신성에는 유의미한 영향을 미치지 않았으나 미래지향성에는 부정적인 영향을 미치는 것으로 나타났다. 반면 스키마는 기업가지향성에 긍정적인 영향을 미치는 것으로 나타났으며 기업가지향성도 창업의도에 긍정적인 영향을 미치는 것으로 나타났다. 본 연구결과에 따르면 ADHD 성향이 높을수록 미래지향성이 낮아서 창업의도에 부정적인 영향을 미치나 스키마는 기업가지향성을 통해서 창업의도에 긍정적인 영향을 미치는 것으로 나타났다.

• 한국의류산업학회지
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• 제18권2호
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• pp.158-166
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• 2016

This study investigates the impact of fashion product attributes and mobile shopping mall attributes on impulse buying behavior and mobile shopping satisfaction. The findings provide new information to marketers on marketing strategy for mobile shopping malls. We obtained 283 usable questionnaires from college students. Data were analyzed by frequency analysis, correlation analysis, factor analysis using SPSS for Window 21.0 and confirmatory factor analysis and structural equation model analysis by AMOS 21.0. The results were as follows. The utility of fashion products attributes had the greatest impact on impulse buying behavior when buying fashion products in a mobile mall. Utility had a negative effect on impulsive buying behavior and exhibitionistic had a positive effect on impulsive buying behavior. Next, continuous management of mobile shopping mall attributes influenced impulse buying behavior. In addition, impulse buying behavior showed that the positive effect on satisfaction. Fashion product attributes had a greater impact on impulsive buying behavior than mobile mall properties when buying fashion products in the mobile mall; in addition, impulse buying facilitated customer satisfaction.

• Composites Research
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• 제23권1호
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• pp.8-16
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• 2010

섬유금속 적층판(FMLs)은 손상허용도를 향상시키고 무게를 줄이는데 적합하여 항공우주 응용의 신소재로 각광을 받고 있다. 본 연구에서는 우선 섬유와 알루미늄을 이용하여 적층판을 제조하여 인장시험을 수행 후 FMLs의 기계적 물성을 평가하였다. 또한 알루미늄과 섬유적층의 변화를 주어 낙추충격시험기(Drop Weight Impact Tester)를 이용하여 저속충격하에서 낙추 높이를 조절하여 각 종류의 시험편 마다 충격시간에 따른 하중과 충격흡수에너지를 각각 비교하였다. 추가로 유한요소해석을 이용하여 시험조건과 동일 조건하 인장과 충격거동해석을 수행한 결과를 실험치와 비교하여 실험과 이론해석이 잘 일치함을 보였다.

• Structural Engineering and Mechanics
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• 제82권2호
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• pp.173-189
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• 2022

This study presents an experimental and numerically study about the effects of fiber reinforcement ratio on the behavior of concrete-filled steel tubes (CFST) under dynamic impact loading. In literature have examined the behavior of GFRP and FRP wrapped strengthened CFST elements impact loads. However, since the direction of potential impact force isn't too exact, there is always the probability of not being matched the impact force of the area where the reinforced. Therefore, instead of the fiber textile wrapping method which strengthens only a particular area of CFST element, we used fiber-added concrete-filled elements which allow strengthening the whole element. Thus, the effect of fiber-addition in concrete on the behavior of CFST elements under impact loads was examined. To do so, six simply supported CFST beams were constructed with none fiber, 2% fiber and 10% fiber reinforcement ratio on the concrete part of the CFST beam. CFST beams were examined under two different impact loads (75 kg and 225 kg). The impactors hit the beam from a 2000 mm free fall during the experimental study. Numerical models of the specimens were created using ABAQUS finite element software and validated with experimental data. The obtained results such as; mid-span displacement, acceleration, failure modes and energies from experimental and numerical studies were compared and discussed. Furthermore, the Von Misses stress distribution of the CFST beams with different ratio of fiber reinforcements were investigated numerically. To sum up, there is an optimum amount limit of the fiber reinforcement on CFST beams. Up to this limit, the fiber reinforcement increases the structural performances of the beam, beyond that limit the fiber reinforcement decreases the performances of the CFST beam under transverse impact loadings.

• Steel and Composite Structures
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• 제42권2호
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• pp.277-288
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• 2022

A novel flat steel plate-concrete-corrugated steel plate (FS-C-CS) sandwich panel was proposed for resisting impact load. The failure mode, impact force and displacement response of the FS-C-CS panel under impact loading were studied via drop-weight impact tests. The combined global flexure and local indentation deformation mode of the FS-C-CS panel was observed, and three stages of impact process were identified. Moreover, the effects of corrugated plate height and steel plate thickness on the impact responses of the FS-C-CS panels were quantitatively analysed, and the impact resistant performance of the FS-C-CS panel was found to be generally improved on increasing corrugated plate height and thickness in terms of smaller deformation as well as larger impact force and post-peak mean force. The Finite Element (FE) model of the FS-C-CS panel under impact loading was established to predict its dynamic response and further reveal its failure mode and impact energy dissipation mechanism. The numerical results indicated that the concrete core and corrugated steel plate dissipated the majority of impact energy. In addition, employing end plates and high strength bolts as shear connectors could prevent the slip between steel plates and concrete core and assure the full composite action of the FS-C-CS panel.

• 한국압력기기공학회 논문집
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• 제14권1호
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• pp.38-47
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• 2018

For safe operation of nuclear power plants, a loose-part monitoring system (LPMS) is used to detect and locate loose-parts within the reactor coolant system, and to estimate their mass and damage potential. There are several methods to estimate mass, such as the center frequency method based on the Hertz's impact theory, a frequency ratio method and so on, but it is known that these methods cannot provide accurate information on impact response for identifying the impact source. Thanks to increasing computing power, finite element analysis (FEA) method recently become an available option to calculate reliably impact response behavior. In this paper, a finite element analysis model to simulate the propagation behavior of the bending wave, generated by a metal ball impact, is validated by performing a series of impact tests and the corresponding finite element analyses for flat plate and shell structures. Also, a FEA-based metal sphere signal map is developed, and then blind tests are performed to verify the map. This study provides an accurate simulation method for predicting the metal impact behavior and for building a metal sphere signal map, which can be used to estimate the mass of loose-parts on site in nuclear power plants.

• Computers and Concrete
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• 제11권1호
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• pp.63-73
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• 2013

In this study, the effect of reducing cement by proportional addition of waste powder rubber on the performance of concrete under impact three-point bending loading were investigated experimentally and numerically. Concrete specimens were prepared by adding 5%, 10% and 20 % of rubber powder as filler to the mix and decreasing the same percentage of cement. For each case, three beams of $50mm{\times}100mm{\times}500mm$ were loaded to failure in a drop-weight impact machine by subjecting them to 20 N weight from 300mm height, while another three similar beams were tested under static load. The bending load-displacement behavior was analyzed for the plain and rubberized specimens, under static and impact loads. A three dimensional finite-element method simulation was also performed by using LUSAS V.14 in order to study the impact load-displacement behavior, and the predictions were validated with the experimental results. It was observed that, despite decreasing the cement content, the proportional addition of powder rubber until 10% could yield enhancements in impact tup, inertial load and bending load.