• Fibers and Polymers
• /
• 제1권1호
• /
• pp.45-54
• /
• 2000

Impact behaviors of the large deformable composites of Kevlar fiber reinforced composites of different preform structures have been investigated. An analytic tool was developed to characterize the impact behavior of the Kevlar composites. The image analysis technique, and deply technique were employed to develop energy balance equation under impact loading. An energy method was employed to establish the impact energy absorption mechanism of Kevlar multiaxial warp knitted composites. The total impact energy was classified into four categories including delamination energy, membrane energy, bending energy and rebounding energy under low velocity impact. Membrane and bending energy were calculated from the image analysis of the deformed shape of impacted specimen and delamination energy was calculated using the deplying technique. Also, the impact behavior of Kevlar composites under high velocity impact of full penetration of the composite specimen was studied. The energy absorption mechanisms under high velocity impact were modelled and the absorbed energy was classified into global deformation energy, shear-out energy, deformation energy and fiber breakage energy. The total energy obtained from the model corresponded reasonably well with the experimental results.

• 한국학교ㆍ지역보건교육학회지
• /
• 제12권1호
• /
• pp.91-102
• /
• 2011

Objectives: The purpose of this study is to identify the extent of the health behaviors of juveniles with experience in drug and the extent of their oral health behaviors. Then the impact of such factors on the oral health was analyzed. Methods: The analysis in this study used the raw data from 'The Fifth Korea Youth Risk Behavior Web-based Survey' after getting approval for use from the Center for Disease Control. The research subjects of this study were juveniles with experience in drug. Analysis was done by using 8 socio-demographic variables, 6 health behaviors related variables, 4 oral-health behaviors related variables and 1 oral health related variable. All survey data were analyzed by SPSS WIN 17.0 program. as frequency analysis and logistic regression. Results: The factors that give impact on the oral health of juveniles with drug experience were found as: gender, academic year, study grade, school type, school class, city scale, economic status, residential type, experience in alcohol, experience in smoking, obesity, frequency of medium-level physical exercise, eating breakfast frequency, hours of sleeping, number of tooth-brushing in one day, brushing teeth after lunch frequency, experience in dental treatment and experience in oral health training. Conclusions: In order to improve the oral health of juveniles with drug experience, health behaviors such as stop-smoking, stop-drinking and regular physical exercise are recommended. In addition, they should stop using drugs that threats their oral health. The development of nursing intervention to maintain the continuous enhancement of their oral health is also required.

• 대한조선학회논문집
• /
• 제45권6호
• /
• pp.726-734
• /
• 2008

While the structural safety assessment of Cargo Containment System(CCS) in membrane type LNG carriers has to be carried out in consideration of sloshing impact pressure, it is very difficult to figure out its dynamic response behaviors due to its very complex structural arrangements/materials and complicated phenomena of sloshing impact loading. For the development of its original technique, it is necessary to understand the characteristics of dynamic response behavior of CCS structure under sloshing impact pressure. In this study, for the exact understanding of dynamic response behavior of CCS structure in membrane Mark III type LNG carriers under sloshing impact pressure, its wet drop impact response analyses were carried out by using Fluid-Structure Interaction(FSI) analysis technique of LS-DYNA code, and were also validated through a series of wet drop experiments for the enhancement of more accurate shock response analysis technique. It might be thought that the structural response behaviors of impact response analysis, such as impact pressure impulses and resulted strain time histories, generally showed very good agreement with experimental ones with very appropriate use of FSI analysis technique of LS-DYNA code, finite element modeling and material properties of CCS structure, finite element modeling and equation of state(EOS) of fluid domain.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집A
• /
• pp.174-179
• /
• 2001

In order to investigate the fracture behaviors(perforation modes) and resistance to perforation during ballistic impact of aluminum alloy plate, ballistic tests were conducted. Depth of penetration experiments with 5.56mm-diameter ball projectile launched into 25mm-thickness Al 5052-H34 targets were conducted. A powder gun launched the 3.55g projectiles at striking velocities between 0.6 and 1.0 km/s. radiography of the damaged targets showed different penetration modes as striking velocities increased. Resistance to perforation is determined by the protection ballistic limit($V_{50}$), a statistical velocity with 50% probability for complete perforation. Fracture behaviors and ballistic tolerance, described by perforation modes, are respectfully observed at and above ballistic limit velocities, as a result of $V_{50}$ test and Projectile Through Plates (PTP) test methods. PTP tests were conducted with $0^{\circ}$ obliquity at room temperature using 5.56mm ball projectile. $V_{50}$ tests with $0^{\circ}$ obliquity at room temperature were conducted with projectiles that were able to achieve near or complete perforation during PTP tests. The effect of various impact velocity are studied with depth of penetration.

• 대한기계학회논문집A
• /
• 제20권12호
• /
• pp.3847-3855
• /
• 1996

In order to study the relationship between static and cynamic behaviors of silion caride, both quasi-static indentaiton and impact experiments of spherical particle have been conducted. The difference inmaterial behavior when using the two mehtods suggests a loading rate difference in the damate pattrern and fracture strength of silicon carbide. This investigation showed some difference in damage pattern according to particla property, especially inthe case of particle impact. There was no differences in deformation behaviors according to the loading rate when the crater profiles were compared with each other at the same contact radius. From the result of residual strength evaluation, it was found that the strength degradation began at the initiation of ring crack and its behavior was colsely related to morphologies of the damage developed which was also dependent upon the extent of deformation atthe loaidng point. In the case of static indentation, there didnot exist the particle property effects onthe strength degradation behavior.

• The Journal of Asian Finance, Economics and Business
• /
• 제8권11호
• /
• pp.179-190
• /
• 2021

The purpose of this study is to understand the impact of influencers on generation Z (Gen Z) in the online environment. This article has applied the theories of source credibility, TAM, IAM, and TPB to identify influencer characteristics that affect the purchasing behaviors of Gen Z customers. This research was conducted using a Google Form survey with 24 pre-designed questions. A total of 464 valid questionnaires from Gen Z Vietnamese were collected between November 2020 and January 2021. Data was analyzed using partial least squares structural equation modeling (PLS-SEM) with SmartPLS 3 software. The analysis results confirmed that the components of influencer credibility have a positive impact on Gen Z's purchasing behaviors under the mediated influence of argument quality, perceived usefulness, and social influence. Surprisingly, for Gen Z, the influencers' attractiveness has the strongest impact on their online behavior. More specifically, attractiveness plays the most important role in the perceived usefulness and social influence of Gen Z customers, while influencers' expertise has the strongest impact on argument quality delivered to customers. This study provides evidence of a change in the way Gen Z responds to marketing activities. They are more drawn by the attraction of influencers than their expertise.

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

• 한국콘텐츠학회논문지
• /
• 제12권11호
• /
• pp.398-411
• /
• 2012

무한경쟁시대에 돌입한 호텔산업은 폭넓은 고객층의 확보와 이를 위한 마케팅이 요구되고 있으며 이런 요구에 효과적인 마케팅 기법으로 영상물 PPL이 각광받고 있다. 따라서 많은 연구들이 영상물 PPL의 효과에 관해 행해져 왔다. 다수의 영상물 PPL에 관한 논문은 영상물 PPL에 의해 이미지는 영향을 받고 이미지에 의해 구매 행동도 영향을 받는다는 결론을 도출했다. 본 논문은 영상물 PPL 효과에 대한 연구가 호텔에 대해서도 선행연구에서와 같이 동일한 결과가 도출되는지 확인하고자 한다. 이를 위해 4개의 가설이 설정되었고 가설검증을 위해 설문을 통한 통계분석이 실시되었다. 통계분석 결과 설정된 4개의 가설검증 결과는 다음과 같다. 첫째, 영상물 PPL과 호텔 이미지(세련, 고급, 친근 및 전체 이미지)와의 영향관계를 부분적으로 확인하였다. 둘째, 등장인물 관여도에 따라 영상물 PPL과 호텔 이미지와의 영향관계의 차이를 부분적으로 확인하였다. 셋째, 호텔 이미지와 구매 행동 간의 영향관계를 부분적으로 확인하였다. 넷째, 등장인물 관여도에 따라 호텔 이미지와 구매 행동과의 영향관계의 차이를 부분적으로 확인하였다.

• Steel and Composite Structures
• /
• 제27권4호
• /
• pp.417-426
• /
• 2018

This paper presents the seismic behaviors and restoring force model of ring beam joints of steel tube-reinforced concrete column structure under cyclic loading. First, the main failure mode, ultimate bearing capacity, stiffness degradation and energy dissipation capacity are studied. Then, the effects of concrete grade, steel grade, reinforcement ratio and radius-to-width ratios are discussed. Finally, the restoring force model is proposed. Results show that the ring beam joints of steel tube-reinforced concrete column structure performs good seismic performances. With concrete grade increasing, the ultimate bearing capacity and energy dissipation capacity increase, while the stiffness degradation rates increases slightly. When the radius-width ratio is 2, with reinforcement ratio increasing, the ultimate bearing capacity decreases. However, when the radius-to-width ratios are 3, with reinforcement ratio increasing, the ultimate bearing capacity increases. With radius-to-width ratios increasing, the ultimate bearing capacity decreases slightly and the stiffness degradation rate increases, but the energy dissipation capacity increases slightly.

• Journal of Preventive Medicine and Public Health
• /
• 제55권5호
• /
• pp.455-463
• /
• 2022

Objectives: Economic hardship has a serious impact on adolescents' mental health. The financial impact of the coronavirus disease 2019 (COVID-19) pandemic was more severe for low-income families, and this also impacted adolescents. This study aimed to examine the associations of economic deterioration (ED) caused by the COVID-19 pandemic and low socioeconomic status (SES) with adolescents' suicidal behaviors. Methods: This study analyzed data from the 2020 Korea Youth Risk Behavior Web-based Survey, which included 54 948 middle and high school students. Odds ratios (ORs) of suicidal ideation, suicidal planning, and suicide attempts related to ED and SES were calculated using multivariable logistic regression. We calculated relative excess risks due to interaction to assess additive interactions. Results: The ORs for suicidal ideation, suicidal planning, and suicide attempts related to combined severe ED and low SES were 3.64 (95% confidence interval [CI], 3.13 to 4.23), 3.88 (95% CI, 3.09 to 4.88), and 4.27 (95% CI, 3.21 to 5.69), respectively. Conclusions: ED and low SES were significantly associated with suicidal behaviors in adolescents. Although no significant additive interaction was found, the ORs related to suicidal ideation, suicidal planning, and suicide attempts were highest among adolescents from low-income families with severe ED. Special attention is needed for this group, considering the increased impact of economic inequality due to the COVID-19 pandemic.