• 한국항공우주학회지
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• 제47권9호
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• pp.617-628
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• 2019

벤트홀로 연결된 두 개의 가변 체적 챔버를 가지고 있는 파이로테크닉 분리 너트는 복잡한 과정을 통해 분리를 수행하므로 많은 설계 인자를 가지고 있다. 접촉부의 각도, 구성품의 질량, 누름봉 돌출부 안쪽 지름, 환형 챔버의 초기 부피, 확장 챔버의 초기 부피, 화약질량, 벤트홀 지름과 같은 설계 인자들의 변화에 따라 분리 너트의 성능이 어떻게 달라지는지를 파악하면 설계 개선 방향을 결정하는데 도움이 될 수 있다. 이에, 선행 연구를 통해 개발한 파이로테크닉 분리 너트 거동 예측 모델을 이용하여 매개변수 연구를 수행하였다. 다른 설계 인자의 값은 고정한 상태에서 한 설계인자의 값을 독립적으로 변화시키며 분리 시간이 어떻게 달라지는지, 변화의 원인이 무엇인지를 분석하였다.

• Structural Engineering and Mechanics
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• 제13권6호
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• pp.653-670
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• 2002

In order to ensure the structural dynamic stability of moving liquid-storage containers, the flow motion of interior liquid should be appropriately suppressed by means of mechanical devices such as the disc-type elastic baffle. In practice, the design of a suitable baffle requires a priori the parametric dynamic characteristics of storage containers, with respect to the design parameters of baffle, such as the installation location and inner-hole size, the baffle number, and so on. In this paper, we intend to investigate the parametric effect of the baffle parameters on the transient dynamic behavior of a cylindrical fuel-storage tank in an abrupt vertical acceleration motion. For this goal, we employ the ALE (arbitrary Lagrangian-Eulerian) kinematic description method incorporated with the finite element method.

• 한국연소학회지
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• 제21권1호
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• pp.31-37
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• 2016

Swirler generates the overall swirling flow in the combustion chamber and this swirling flow governs the flame stability and enhances fuel atomization. This paper deals with the flare angle effects on flow streamlines, recirculation zone, Central Toroidal Recirculation Zone(CTRZ) and Corner Recirculation Zone(CRZ) in the model combustion chamber using counter-rotating swirler. 2D PIV system was employed to obtain the velocity components and test condition was obtained using Reynolds Analogy equivalent to air test. We observed transitional flow patterns of flare angle increased. The obtained results show that the flare angle controls the behavior of Recirculation zone, Central Toroidal Recirculation Zone and Corner Recirculation Zone.

• Kyungpook Mathematical Journal
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• 제48권4호
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• pp.593-611
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• 2008

Global attractivity and oscillatory behavior of the following nonlinear impulsive parabolic differential equation which is a general form of many population models $$\array{\{{{\frac {{\partial}u(t,x)}{{\partial}t}=\Delta}u(t,x)-{\delta}u(t,x)+f(u(t-\tau,x)),\;t{\neq}t_k,\\u(t^+_k,x)-u(t_k,x)=g_k(u(t_k,x)),\;k{\in}I_\infty,}\;\;\;\;\;\;\;\;(*)$$ are considered. Some new sufficient conditions for global attractivity and oscillation of the solutions of (*) with Neumann boundary condition are established. These results no only are true but also improve and complement existing results for (*) without diffusion or impulses. Moreover, when these results are applied to the Nicholson's blowflies model and the model of Hematopoiesis, some new results are obtained.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2007년도 가을 학술발표논문집 Vol.34 No.2 (D)
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• pp.27-30
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• 2007

초기의 웜은 감염 및 확산의 신속성을 중요시하였으나, 생존성은 고려하진 않았다. 하지만 보안도구(Anti-worm)의 발달에 따라 2004년 이후 대규모의 웜 확산에 의한 피해가 보고되지 않고 있다. 이에 웜도 보안도구를 회피하는 자기방어(Self-Defense) 기법을 개발하여 생존성을 증가시키면서 진화하고 있다. 본 논문은 현존하는 웜 자기방어 기법과 그 한계를 분석한 후 행동기반 탐지 기법을 우회하는 자기방어 기법을 제안하도록 하겠다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.532-543
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• 2004

The present work have been developed the interpretation processor including the behavior of material failure and the separation phenomena under transient dynamic loading (the operation of explosive bolt) using AUTODYN V4.3, SoildWork 2003 and TrueGrid V2.1 programs. It has been demonstrated that the interpretation in ridge-cut explosive bolt under dynamic loading condition should be necessary to the appropriate failure model and the basic stress of bolt failure is the principal stress. The use of this interpretation processor developing the present work could be extensively helped to design the shape and the amount of explosives in the explosive bolt having a complex geometry. It is also proved that the interpretation processor approach is an accurate and effective analysis technique to evaluate the separation mechanism in explosive bolts.

• 아동학회지
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• 제32권6호
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• pp.15-32
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• 2011

The purpose of the present study was to examine mechanisms by which the characteristics of child temperament influences academic achievement in late childhood. It was hypothesized that the effects of child temperament on achievement would be mediated by assertive behavior on the part of children and maternal parenting behavior. Data for this study came from self-report questionnaires completed by 657 elementary school children (343 boys, 314 girls). The results of structural equation modeling demonstrated that child temperament affected academic achievement through both assertive behavior and maternal parenting behavior; this was evidenced across the entire sample. Child temperament (approach-withdrawal, mood quality, persistence) also had a number of positive effects on assertive behavior (directiveness, social assertiveness, defense of rights and interests) and maternal parental behavior (warmth-acceptance, guidance). These results were found to be the case for both boys and girls. The results of this study further revealed that maternal parenting behavior mediated the relationship between child temperament and achievement for boys, whereas assertive behavior played the same role for girls. These findings suggest the need for different approaches in developing programs to improve levels of academic achievement which give due consideration to child temperament and social behavior as well as parenting, based on child gender.

• 한국분말재료학회지
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• 제21권1호
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• pp.7-15
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• 2014

This study investigated the densification behavior of rhenium alloys including W-25 wt.%Re and Re-2W-1Ta (pure Re) during sintering. The dilatometry experiments were carried out to obtain the in-situ shrinkage in $H_2$ atmosphere. The measured data was analyzed through shrinkage, strain rate and relative density, and then symmetrically treated to construct the linearized form of master sintering curve (MSC) and MSC as a well-known and straightforward approach to describe the densification behavior during sintering. The densification behaviors for each material were analyzed in many respects including apparent activation energy, densification parameter, and densification ratio. MSC with a minimal set of preliminary experiments can make the densification behavior to be characterized and predicted as well as provide guideline to sinter cycle design. Considering the results of linearized form and MSC, it was confirmed that the W-25 wt.%Re compared to Pure Re is more easily densified at the relatively low temperature.

• 한국항공운항학회지
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• 제31권3호
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• pp.17-29
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• 2023

The safe operation of military aircraft is crucial for national defense to prevent unnecessary loss of combat power. With the advancement of technology, the proportion of accidents caused by mechanical defects is decreasing compared to the beginning of aviation history, but the proportion of accidents caused by human factors is increasing. Therefore, it is necessary to identify factors that enhance flight safety behavior from various perspectives and explore related mechanisms. In this study, we examined the relationship between Air Force aircrew's calling and their flight safety behavior. With a sample of 357 Air Force aircrew, we found a significant positive relationship between calling and flight safety behavior, with affective commitment and moral duty mediating this relationship in parallel. We discussed theoretical and practical implications of the study based on these results.

• 한국통신학회논문지
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• 제35권5B호
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• pp.777-784
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• 2010

현대의 정보화 사회에서는 정보기술이 기업과 공공기관에 도입되면서 정보기술 전반을 관리해야 한다는 필요성이 대두되었고, 비즈니스 목표와 IT의 연계 필요성이 증대되고 함께 IT투자의 중복을 방지하고 ROI를 추구하는 조직들이 늘어났다. 이에 여러 선진 기업들이 IT 거버넌스라는 개념을 제창하였다. IT 거버넌스는 기업의 비즈니스와 IT에 영향을 미치는 구조적 결정인자들의 구조 및 동적양상을 나타내며, 비즈니스와 IT 관련 사내외 위원회 및 부서, 그리고 그들의 활동범위 및 연관관계를 나타내는 프레임워크, 조직도 및 프로세스 구성으로 표현이 된다. 이러한 외부적인 요인과 맞물려 현재 우리 군의 국방 비전과 목표를 달성하기 위한 국방 IT 거버넌스의 재확립은 필수적인 사항이 되었다. 본 논문에서는 국방 IT 거버넌스의 프레임워크를 구축하기 위한 핵심 추진전략에 대해서 기술하였다. 이러한 주장에 뒷받침하기 위해서 IT 거버넌스의 전반적인 내용을 기술하고 국내 외와 해외의 군 사례를 분석하여 보고 국방 IT 거버넌스의 프레임워크 구축을 위한 핵심 추진전략을 연구하였다.