• Title/Summary/Keyword: impact behaviors

검색결과 995건 처리시간 0.024초

표면 경화 처리된 Al, Ti의 고속 충격 저항성에 관한 연구 (A Study on the resistance of surface hardening treated Aluminum, Titanium alloy under the high velocity impact)

  • 손세원;김희재;홍성희;김영태
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 춘계학술대회 논문집
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    • pp.852-855
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    • 2002
  • In order to investigate the fracture behaviors(penetration modes) and resistance to penetration during ballistic impact of surface hardening treated Aluminum, Titanium alloy laminates, ballistic tests were conducted. In this paper, Anodized Al 5083-H131 alloy laminates and nitrified Ti (Gr.2) alloy laminates were used to achieve higher surface hardness. Surface hardness test were conducted using a Micro victor's hardness tester and thickness of surface hardening treated specimens was measured by video microscope. Resistance to penetration is determined by the protection ballistic limit($V_50$), a statistical velocity with 50% probability far complete penetration. Fracture behaviors and ballistic tolerance, described by penetration 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 penetration during PTP tests.

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PVD처리한 티타늄 합금의 고속충격 거동에 관한 연구 (A Study on the high velocity impact behavior of titanium alloy by PVD method)

  • 손세원;이두성;홍성희
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집A
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    • pp.567-572
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    • 2001
  • In order to investigate the fracture behaviors(penetration modes) and resistance to penetration during ballistic impact of Titanium alloy laminates and nitrified Titanium alloy laminates which were treated by PVD(Physical Vapor Deposition) method, ballistic tests were conducted. Evaporation, sputtering, and ion plating are three kinds of PVD method. In this research, Ion plating was used to achieve higher surface hardness and surface hardness test were conducted using a Micro vicker's hardness tester. Resistance to penetration is determined by the protection ballistic limit($V_{50}$), a statistical velocity with 50% probability for complete penetration. Fracture behaviors and ballistic tolerance, described by penetration 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. $V_{50}$ test with $0^{\circ}$ obliquity at room temperature were conducted with projectiles that were able to achieve near or complete penetration during PTP tests. Surface hardness, resistance to penetration, and penetration modes of Titanium alloy laminates are compared to those of nitrified Titanium alloy laminates.

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Numerical Simulation of Mechanical Behavior of Composite Structures by Supercomputing Technology

  • Kim, Seung-Jo;Ji, Kuk-Hyun;Paik, Seung-Hoon
    • Advanced Composite Materials
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    • 제17권4호
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    • pp.373-407
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    • 2008
  • This paper will examine the possibilities of the virtual tests of composite structures by simulating mechanical behaviors by using supercomputing technologies, which have now become easily available and powerful but relatively inexpensive. We will describe mainly the applications of large-scale finite element analysis using the direct numerical simulation (DNS), which describes composite material properties considering individual constituent properties. DNS approach is based on the full microscopic concepts, which can provide detailed information about the local interaction between the constituents and micro-failure mechanisms by separate modeling of each constituent. Various composite materials such as metal matrix composites (MMCs), active fiber composites (AFCs), boron/epoxy cross-ply laminates and 3-D orthogonal woven composites are selected as verification examples of DNS. The effective elastic moduli and impact structural characteristics of the composites are determined using the DNS models. These DNS models can also give the global and local information about deformations and influences of high local in-plane and interlaminar stresses induced by transverse impact loading at a microscopic level inside the materials. Furthermore, the multi-scale models based on DNS concepts considering microscopic and macroscopic structures simultaneously are also developed and a numerical low-velocity impact simulation is performed using these multi-scale DNS models. Through these various applications of DNS models, it can be shown that the DNS approach can provide insights of various structural behaviors of composite structures.

인적자본과 혁신행동의 관계에서 조직몰입의 매개효과 -호텔기업을 중심으로- (Mediating Effects of Organizational Commitments on the Relationship between Human Capitals and Innovative Behaviors -Focused on the Hotel Firms-)

  • 하용규
    • 한국콘텐츠학회논문지
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    • 제10권6호
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    • pp.440-449
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    • 2010
  • 본 연구는 호텔기업의 인적자본이 조직몰입 및 혁신행동에 미치는 영향과 조직몰입이 인적자본과 혁신 행동의 관계에 미치는 매개효과를 밝혀내고자 서울지역에 소재한 특등호텔 종사원을 대상으로 실증분석을 시행하였다. 그 결과 인적자본이 조직몰입과 혁신행동에 영향력이 있고, 조직몰입이 혁신행동에 유의한 영향력이 있음을 밝혀냈다. 또한 조직몰입이 인적자본과 혁신행동의 관계에 부분적인 매개효과를 나타냄을 밝혀냈다. 이 결과는 호텔기업 인적자본의 중요성 및 종사원의 조직몰입이 경쟁환경에서 우위를 점하기 위한 중요한 역할을 한다는 새로운 방향을 시사하는 결과라고 할 수 있다.

Paternal Behaviors and Adolescents' Academic Motivation at Low, Moderate, and High Levels of Students' Achievement in Mainland China

  • Cho, Won Jee;Bush, Kevin R.;Xia, Yan;Wilson, Stephan M.;Li, Wenzhen;Peterson, Gary W.
    • Child Studies in Asia-Pacific Contexts
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    • 제4권2호
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    • pp.95-108
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    • 2014
  • The purpose of this study was to examine group differences in paternal behaviors (i.e., paternal connection, paternal punitiveness, and paternal knowledge) within and across three academic achievement levels-low, moderate, and high, and to explore the effects of paternal behaviors on the academic motivation of Chinese adolescents within these three achievement groups. Analyses of variance (ANOVAs) indicated that adolescents with low achievement perceived their fathers as more punitive than teens with moderate and high academic achievement. Regression analyses also revealed that paternal punitiveness (negative) and paternal knowledge (positive) were significant predictors of academic motivation for teens with low levels of academic achievement; while paternal punitiveness was a significant negative predictor of academic motivation among adolescents with moderate achievement. In contrast, for adolescents with high achievement, paternal connection was a positive significant predictor of academic motivation. The present findings provide some evidence that the impact of parental behaviors on teen's motivation varies across adolescent academic achievement levels, which may prove useful for professionals working with fathers to help target the most effective parenting behaviors to foster academic motivation.

간호대학생의 COVID-19 관련 지식, 감염위험지각, 두려움, 자기효능감이 COVID-19 감염 예방행위에 미치는 영향 (The impact of Knowledge, Risk perception, Fear, Self-efficacy on COVID-19 Preventive behaviors in Nursing Students)

  • 손수진;김지현
    • Journal of Korean Biological Nursing Science
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    • 제24권4호
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    • pp.253-261
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    • 2022
  • Purpose: This study aims to identify the knowledge, risk perception, fear, self-efficacy, and preventive behaviors among nursing students, and factors influencing preventive behaviors on COVID-19. Methods: Data was collected from March, 2022 to May, 2022. The participants included 218 nursing students in their 3rd and 4th grade of three universities in two cities. Results: The knowledge of COVID-19 was 13.54 out of 15 points, risk perception was 4.83 out of 8 points, fear was 13.26 out of 35 points, self-efficacy was 19.96 out of 25 points, and preventive behaviors were 7.56 out of 9 points. The explanatory power of self efficacy (β= .21, p= .002), which affects preventive behaviors was 67.0%. Conclusion: Based on the results of this study, it is necessary to develop a systematic nursing intervention that improves self-efficacy to improve preventive behaviors against COVID-19 among students. This study's result can be used in the future to develop appropriate health policies and program to prevent emerging infectious diseases.

Application of Risk Information Seeking and Processing Model to the Health Preventive Behavior: How Risk Susceptibility and Political Identity affect Vaccination

  • SoYoung Lee;Seoyeon Hong;Bokyung Kim
    • International Journal of Internet, Broadcasting and Communication
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    • 제15권4호
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    • pp.9-20
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    • 2023
  • In the aftermath of the COVID-19 pandemic, the importance of collective efforts in promoting health preventive behaviors is accentuated, bringing sociopolitical factors into focus. To fully capture psychological drivers of health preventive behaviors in risk situations, anchored on the Model of Risk Information Seeking and Processing (RISP; Griffin, Dunwoody, and Neuwirth 1999), in retrospect of the recent COVID-19 pandemic, we explored whether and how individuals' vaccination behaviors are predicted by RISP-related variables (information insufficiency, affective responses, perceived information gathering capacity, subjective norms) and one's political identity. Findings from a survey of 705 adult participants in the U.S. showed that the effects of one's risk information insufficiency on his or her information seeking and affective response regarding the pandemic, which is also related to their risk susceptibility perceptions. More importantly, the impact of political identity on one's perceived risk susceptibility, and its association with vaccination behaviors are also identified. The findings of this study provide valuable insights for the development of effective health communication strategies for preventive health behaviors.

Comparing the Effects of Two Methods of Education (Online versus Offline) and Gender on Information Security Behaviors

  • Minjung Park;Sangmi Chai
    • Asia pacific journal of information systems
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    • 제30권2호
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    • pp.308-327
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    • 2020
  • The importance of information security is increasing, and various efforts are being made to improve users' information security behaviors. Among these various efforts, information security education is mainly aimed at providing users with information security knowledge and improving information security awareness. This study classified the types of information security education into offline and online to examine the effects of each education method on attitudes toward information security (perceived severity, vulnerability, self-efficacy and response-efficacy) and information security behaviors. A survey was conducted for users with information security education experiences. The results obtained by comparing the differences in the path coefficients of personal information security behaviors according to information security education experiences showed that security behaviors were more significant in the online experience group than the offline group. In addition, gender differences were analyzed, and it was found that females had a greater impact on information security attitudes than males. This study also found that among Internet users with online information security education experience, females tend to have more information security behavior than males, but there were contrasting results among users with offline information security education experiences. The results of this study finally address the necessity of reflecting users' personalities in the systematic design of information security education in the future. Furthermore, the results of this study support the need for an appropriate education system that sufficiently understands education types to maximize the effects of information security education.