• 한국전산구조공학회논문집
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• 제29권4호
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• pp.369-376
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• 2016

이 연구는 화재에 노출된 구조물의 역학적 거동을 평가하기 위한 기반연구로서 화재 유동해석과 열응력해석의 통합 프레임워크를 확립하고 이를 강재와 콘크리트로 이루어진 대표체적에 적용한 결과를 제시하였다. 먼저 Fire Dynamics Simulator(FDS)를 이용해 임의의 화재곡선으로 모델링되는 화원으로부터 구조물 표면까지 유동해석을 실시하였다. 이를 통해 구조물 표면에서 시간에 따른 온도 분포를 계산하였고, 이 결과를 비선형 열응력해석에 경계조건으로 적용하였다. 이후의 과정은 화재의 성장 또는 감소에 따라 구조물 표면온도의 변화를 반영하는 열전달해석과 구조해석으로 이루어진다. 제시한 통합 프레임워크에 의해 화재 구조해석을 수행한 결과, 강재와 콘크리트의 대표체적 모두 동일한 하중이 작용할 때 상온 조건에서는 탄성 거동을 보였지만 화재로 인한 온도 조건을 고려할 경우 소성 거동을 보였다. 이는 구조물이 화재에 노출되는 경우 설계하중보다 작은 하중에서도 한계상태에 이를 수 있다는 것을 의미하며, 따라서 원전구조물이나 교량과 같은 중요 사회기반구조물의 설계 시 구조물의 화재거동 평가가 고려되어야 한다고 할 수 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.881-887
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• 2000

The interest in evaluation of structural intensity arises for practical reasons, because net energy flow distribution offers information of energy transmission path, positions of sources, and sinks of vibration energy. In this paper, structural intensity analysis of local ship structures using finite element method(FEM) is carried out. The purpose of this analysis is to evaluate the relative accuracy according to mesh fineness. The structural intensity of a stiffened plate varying their mesh fineness is analyzed and the results are compared with those obtained by the assumed made method. As results, the proper mesh size in qualitative/quantitative structural intensity analysis of plate structures is proposed. In addition, the propagation phenomenon of vibration energy is investigated for the L-type plate and box-girder structures.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1061-1066
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• 2001

To predict vibrational energy density and intensity of beam-plate coupled complex structures in medium-to-high frequency ranges, Power Flow Finite Element Method(PFFEM) programs for plate, beam and some coupled structural elements are developed. The flexural, longitudinal and shear waves in plates are formulated and the joint element equations for multi-couped plates are fully developed. Also the wave transmission approach has been introduced to cover the energy transmission and reflection at the joint elements. Using the developed PFFEM program, vibration analysis for 2300TEU container ship model is performed and here the model data for this program are obtained by converting fonner FE model for structural analysis. This program predicts successfully the vibrational energy density and intensity upto 8,000 Hz for the ship model with over 50,000 DOF.

• 패션비즈니스
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• 제27권1호
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• pp.50-60
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• 2023

The purpose of this study was to understand the factors with consumers' fashion experiential store experiences and investigate the effect on flow and brand attitude. The study also aimed to investigate whether gender moderated the relationship between consumers' fashion experiential store experiences and flow. An online survey of consumers in their 20s and 40s was conducted. The SPSS 27.0 program was used to perform frequency, factor, and reliability analysis. The structural equation model was analyzed using the SMART-PLS program. The structural model analysis confirmed that consumers' rational, physical, and relational experiences in fashion brand experiential stores strongly influenced flow and found that relational experience had the strongest influence on flow. The influence of rational, physical, and relational experiences and flow on brand attitude was confirmed, where flow had the strongest effect on brand attitude. The examination of the moderating effect of gender on the relationship between consumers' fashion experiential store experiences and flow found that the effect in men was significant for flow and brand attitude through rational experience and that the effect in women was significant for flow and brand attitude through relational experience. These results provide academic implications, and by strengthening consumer flow, we intend to propose the establishment of a marketing strategy and opportunity plan that can elicit a positive brand attitude.

• Structural Engineering and Mechanics
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• 제43권3호
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• pp.395-410
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• 2012

The visualizing energy flow and control in vibrating stiffened plates with a cutout are studied using finite element method. The vibration intensity, vibration energy and strain energy distribution of stiffened plates with cutout at different excitation frequencies are calculated respectively and visualized for the various cases. The cases of different size and boundaries conditions of cutouts are also investigated. It is found that the cutout or opening completely changes the paths and distributions of the energy flow in stiffened plate. The magnitude of energy flow is significantly larger at the edges near the cutout boundary. The position of maximum strain energy distribution is not corresponding to the position of maximum vibrational energy. Furthermore, the energy-based control using constrained damping layer (CDL) for vibration suppression is also analyzed. According to the energy distribution maps, the CDL patches are applied to the locations that have higher energy distribution at the targeted mode of vibration. The energy-based CDL treatments have produced significant attenuation of the vibration energy and strain energy. The present energy visualization technique and energy-based CDL treatments can be extended to the vibration control of vehicles structures.

• 한국항공운항학회지
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• 제30권3호
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• pp.38-53
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• 2022

Recently, the acquisition and production of information using digital tools and the creation of new knowledge are emphasized as important educational elements. Therefore, in this study, the effect of learning achievement according to the digital literacy level of college students was analyzed. For the analysis, a questionnaire is conducted with college students majoring in aviation services attending universities in Seoul Capital Area and Chungcheong area. To verify the hypothesis of the study, demographic characteristics are identified based on the questionnaire, reliability and validity of measurement items are verified, and structural equation model analysis is performed to verify the hypothesis. The analysis results are as follows. First, among the sub-factors of digital literacy competency of college students majoring in aviation service, 'technology use' is found to have a positive effect on 'cognitive flow' and 'emotional flow' of learning flow except 'behavioral flow'. Second, among the sub-factors of digital literacy competency, 'self-learning' is found to have a positive effect on 'cognitive flow', 'emotional flow', and 'behavioral flow' in learning flow. Third, the sub-factors of learning flow, 'cognitive flow', 'emotional flow', and 'behavioral flow' have a positive effect on 'learning satisfaction'. Fourth, 'learning satisfaction' is found to have a positive effect on 'learning outcomes'. Based on the research results, practical support measures and strategies for educational success are presented.

• Journal of Mechanical Science and Technology
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• 제16권3호
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• pp.395-402
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• 2002

This paper shows how to formulate the transient analysis of 2-dimensional Hagen-Poiseuille flow using smoothed particle hydrodynamics (SPH). Treatments of viscosity, particle approximation and boundary conditions are explained. Numerical tests are calculated to examine effects caused by the number of particles, the number of particles per smoothing length, artificial viscosity and time increments for 2-dimensional Hagen-Poiseuille flow. Artificial viscosity for reducing the numerical instability directly affects the velocity of the flow, though effects of the other parameters do not produce as much effect as artificial viscosity. Numerical solutions using SPH show close agreement with the exact ones for the model flow, but SPH parameter must be chosen carefully Numerical solutions indicate that SPH is also an effective method for the analysis of 2-dimensional Hagen-Poiseuille flow.

• 한국가스학회지
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• 제24권3호
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• pp.47-53
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• 2020

본 연구에서는 엔진발전기에 사용되는 냉각팬 형상을 단방향 유동-구조 연성해석을 통하여 냉각팬의 성능과 내구성을 분석하여 최적화 설계자료를 제시하였다. 이를 위해, 냉각팬 내부 유동장에 대해 정상상태 해석을 수행하고, 정상상태 계산 결과를 구조해석을 위한 입력 데이터로 사용함으로써 내구성을 분석하였다. 냉각팬의 블레이드와 스윕 각도를 변경하는 작업을 통해 6가지 type을 모델링하여 유동해석을 진행하였으며, 질량유량과 토오크의 비는 A type이 가장 우수하지만, 질량유량이 상대적으로 큰 B type이 유동성능이 가장 좋은 냉각팬의 형상이라고 판단하였다. 유동해석을 통해 선정된 B type의 블레이드 두께를 4가지로 설정하여 구조해석을 검토한 결과, 피로안전계수까지 고려하였을 때 B Type-3가 가장 적합하다고 판단되었다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(2)
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• pp.1001-1007
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• 1995

A Comprehensive Vibration Assessment Program (CVAP) has been performed for Yonggwang Nuclear Power Plant Unit 4 (YGN 4) in order to verify the structural integrity of the reactor internals for flow induced vibrations prior to commercial operation. The theoretical evidence for the structural integrity of the reactor internals and the basis for measurement and inspection are provided by the analysis. Flow induced hydraulic loads and reactor internals vibration response data were measured during pre-core hot functional testing in YGN 4 site. Also, the critical areas in the reactor internals were inspected visually to check any existence of structural abnormality before and after the pre-core hot functional testing. Then, the measured data have been analyzed and compared with the predicted data by analysis. The measured stresses are less than the predicted values and the allowable limits. It is concluded that the vibration response of the reactor internals due to the flow induced vibration under normal operation is acceptable for long term operation.

• 대한조선학회논문집
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• 제42권5호
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• pp.487-492
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• 2005

The structural intensity analysis, which calculates vibration energy flow from vibratory velocity and internal force of a structure, can give information on sources' power, dominant transmission path and sink of vibration energy. In this study, we present a system for structural intensity analysis and visualization to apply for anti-vibration design of ship structures. The system calculates structural intensity from the results of forced vibration analysis and visualize the intensity using a general purpose finite element analysis program MSC/Nastran and its pre- and post-processor program. To demonstrate the analysis and visualization capability of the presented system, we show and discuss the results of structural intensity analysis for a cross-stiffened plate and a 70,500 OW crude oil tanker