• Steel and Composite Structures
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• 제1권4호
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• pp.427-440
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• 2001

The growing use of unprotected or partially protected steelwork in buildings has caused a lively debate regarding the safety of this form of construction. A good deal of recent research has indicated that steel members have a substantial inherent ability to resist fire so that additional fire protection can be either reduced or eliminated completely. A performance based philosophy also extends the study into the effect of structural continuity and the performance of the whole structural totality. As part of the structural system, thermal expansion during the heating phase or contraction during the cooling phase in most beams is likely to be restrained by adjacent parts of the whole system or sub-frame assembly due to compartmentation. This has not been properly addressed before. This paper describes an experimental programme in which unprotected steel beams were tested under load while it is restrained between two columns and additional horizontal restraints with particular concern on the effect of catenary action in the beams when subjected to large deflection at very high temperature. This paper also presents a three-dimensional mathematical modelling, based on the finite element method, of the series of fire tests on the part-frame. The complete analysis starts with an evaluation of temperature distribution in the structure at various time levels. It is followed by a detail 3-D finite element analysis on its structural response as a result of the changing temperature distribution. The principal part of the analysis makes use of an existing finite element package FEAST. The effect of columns being fire-protected and the beam being axially restrained has been modelled adequately in terms of their thermal and structural responses. The consequence of the beam being restrained is that the axial force in the restrained beam starts as a compression, which increases gradually up to a point when the material has deteriorated to such a level that the beam deflects excessively. The axial compression force drops rapidly and changes into a tension force leading to a catenary action, which slows down the beam deflection from running away. Design engineers will be benefited with the consideration of the catenary action.

• 디지털융복합연구
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• 제19권5호
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• pp.269-277
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• 2021

이 연구의 목적은 대학의 온라인 수업에 대한 대학의 운영 및 시스템지원이 학습실재감을 매개로 학습참여도에 미치는 영향을 분석하고 구성요인들 간의 구조적 관계를 탐색하는 것이다. 연구목적을 달성하기 위해 온라인수업으로 이루어지는 공통교양과목 중 '대학영어2' 수강생 135명을 대상으로 구조방정식 모형의 확인적 요인분석을 통해 연구모형의 적합도 분석과 경로구조 분석을 실시했다. 연구결과, 첫째, 온라인 수업환경에 대한 대학의 운영지원이 학습자의 학습실재감에 정적인 영향을 치는 것으로 나타났다. 둘째, 온라인 수업환경에 대한 대학의 운영지원이 학습실재감을 완전매개하여 학습참여도에 긍정적 영향을 미치는 것으로 나타났다. 본 연구는 대학의 온라인 수업에서 환경특성 요인인 온라인 수업에 대한 지원, 학습자 특성 요인으로 학습실재감, 학습참여도간의 구조적 관계를 규명하여 온라인 학습장면에서 학습참여도에 대한 이해의 폭을 넓히고 교수·학습 설계에 고려해야 하는 시사점을 제시해 주었다는 점에서 연구의 의의를 지닌다.

• 한국산업융합학회 논문집
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• 제23권2_2호
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• pp.361-374
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• 2020

Recently, small and medium-sized rahmen-type bridges have been developed as a technology that ensures the stability of structural behavior and the safety of use at the same time by using efficient and economical materials that make up the convergence section of reinforced bar, structural steel and concrete. This study is about a rahmen-type structure applied with the installation and dismantling of the strut. It improves the serviceability of the structure by forming multi-points and efficiently applies the convergence section of structural steel and concrete materials to the structural system changes to induce the displacement improvement effect additionally. By constructing mock-up models for the beam-column joint, the displacement was calculated and compared, and this was compared and analyzed by numerical analysis. The final displacement showed an improvement effect of 13.46% to 36.28% based on the vertical displacement of the existing structure without struts through the experiment of the mock-up models. As a result of analysis by numerical analysis method, the displacement improvement effect of 42.89% could be derived.

• 가정과삶의질연구
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• 제30권2호
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• pp.75-86
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• 2012

The purpose of this study was to investigate the structural relationships school-aged children and related variables. For this study, the respondents were 704 children in elementary schools in the areas of Gyeongsan-Si and Daegu-Si. The questionnaires and psychological tests used in this study surveyed the following concepts: suicide ideation, social support, self-esteem and the scale of depression. The collected data were analyzed with AMOS 19.0, a statistical program for structural equation modeling, to estimate the hypothesized structural equation model. The results were as follows: First, self-esteem, - and depression as perceived by children were found to affect their suicide ideation directly. Second, parental support and teacher support as perceived by children were found to affect children's depression directly. Third, parental support, teacher support, and the support of friend's as perceived by children were found to affect-children's self-esteem directly. Last, parental support and, teacher's support did not show direct effect on children's suicide ideation, though these factors had an indirect effect on suicide ideation through the children's self-esteem and depression. Finally, teacher's support did not direct effectly children's suicide ideation, whereas it had an having indirect effect on suicide ideation through the children's self-esteem.

• 디지털융복합연구
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• 제9권4호
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• pp.115-130
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• 2011

본 연구는 IT서비스 기술인력의 경력정체(구조적 정체, 내용적 정체)가 경력만족 및 경력변경의 도에 미치는 영향을 분석하였다. 161명의 IT서비스 기술인력으로 부터 데이터를 수집하였다. 구조적 정체와 내용적 정체는 각각 경력만족에 부의 유의한 상관을 갖고 있었다. 그리고 내용적 정체는 경력변경의도와 정의 유의한 상관을 갖고 있었으며, 구조적 정체는 이와 유의한 상관을 갖고 있지 않았다. 위계적 다중회귀분석에 의한 상대적 영향력 분석 결과 구조적 정체 보다 내용적 정체가 경력만족 및 경력변경의도에 더 큰 유의한 영향을 미치고 있었다. 마지막으로 본 연구는 IT서비스 기술인력의 경력정체를 극복하기 위한 방안을 제시하고 있다.

• Nuclear Engineering and Technology
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• 제49권1호
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• pp.254-266
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• 2017

Finite-element analysis based on elastic-perfectly plastic material was conducted to examine the influence of structural deformations on collapse loads of circumferential through-wall critically cracked $90^{\circ}$ pipe bends undergoing in-plane closing bending and internal pressure. The critical crack is defined for a through-wall circumferential crack at the extrados with a subtended angle below which there is no weakening effect on collapse moment of elbows subjected to in-plane closing bending. Elliptical and semioval cross sections were postulated at the bend regions and compared. Twice-elastic-slope method was utilized to obtain the collapse loads. Structural deformations, namely, ovality and thinning, were each varied from 0% to 20% in steps of 5% and the normalized internal pressure was varied from 0.2 to 0.6. Results indicate that elliptic cross sections were suitable for pipe ratios 5 and 10, whereas for pipe ratio 20, semioval cross sections gave satisfactory solutions. The effect of ovality on collapse loads is significant, although it cancelled out at a certain value of applied internal pressure. Thinning had a negligible effect on collapse loads of bends with crack geometries considered.

• Smart Structures and Systems
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• 제18권3호
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• pp.541-568
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• 2016

The goal of this study is to investigate the effect of non-synchronous sensing when using wireless sensors on structural identification and to attempt correcting such errors in order to obtain a better identification result. The sources causing non-synchronous sensing are discussed first and the magnitudes of such synchronization errors are estimated based on time stamps of data samples collected from Imote2 sensors; next the impact of synchronization errors on power spectral densities (PSDs) and correlation functions of output responses are derived analytically; finally a new method is proposed to correct such errors. In this correction method, the corrected PSDs of output responses are estimated using non-synchronous samples based on a modified FFT. The effect of synchronization errors in the measured output responses on structural identification and the application of this correction method are demonstrated using simulation examples. The simulation results show that even small synchronization errors in the output responses can distort the identified modal and stiffness parameters remarkably while the parameters identified using the proposed correction method can achieve high accuracy.

• International journal of advanced smart convergence
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• 제10권3호
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• pp.172-180
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• 2021

The purpose of this study is to analyze the structural relationship among perfectionism and dance achievement of middle and high school students majoring in dance. Specifically, this study aims to investigate the effects of perfectionism on dance achievement through the medium of dance commitment and career decision-making self-efficacy. For this purpose, a structural equation model based on the previous studies was constructed with perfectionism as an exogenous variable and dance commitment, career decision-making self-efficacy, and dance achievement as endogenous variables. The final subjects of this study were 279 middle and high school students majoring in dance. The data were processed by frequency analysis to find out personal characteristics using SPSS 23 and exploratory factor analysis and reliability analysis were conducted on the research tools. In addition, AMOS 21 was used for confirmatory factor analysis, correlation analysis and structural equation model analysis. As a result of data processing on the research model. First, the sub-dimensions of perfectionism tendency 'worry about mistakes', 'personal standard', and 'doubt about behavior' had a statistically significant effect on dance commitment. Second, the sub-dimensions of perfectionism 'worry about mistakes', 'personal standard', and 'doubt about behavior' had statistically significant effects on career decision-making self-efficacy. Third, dance commitment did not have a statistically significant effect on dance achievement, but career decision-making self-efficacy had a statistically significant effect on dance achievement. These results provide implications.

• Structural Engineering and Mechanics
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• 제77권3호
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• pp.369-381
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• 2021

The seismic responses of elevated tanks considering liquid-structure interaction are presented under horizontal earthquake. The scaled model tank is fabricated to study the dynamic responses of anchored tank and newly designed uplift tank with replaced dampers. The natural frequencies for structural mode are obtained by modal analysis. The dynamic responses of tanks are completed by finite element method, which are compared with the results from experiment. The displacement parallel and perpendicular to the excitation direction are both gained as well as structural acceleration. The strain of tank walls and the axial strain of columns are also obtained afterwards. The seismic responses of liquid storage tank can be calculated by the finite element model effectively and the results match well with the one measured by experiment. The aim is to provide a new type of tank system with vertical constraint relaxed which leads to lower stress level. With the liquid volume increasing, the structural fundamental frequency has a great reduction and the one of uplift tank are even smaller. Compared with anchored tank, the displacement of uplift tank is magnified, the strain for tank walls and columns parallel to excitation direction reduces obviously, while the one perpendicular to earthquake direction increases a lot, but the values are still small. The stress level of new tank seems to be more even due to uplift effect. The new type of tank can realize recoverable function by replacing dampers after earthquake.

• International journal of advanced smart convergence
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• 제10권2호
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• pp.194-200
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• 2021

The purpose of this study is to analyze the structural relationship among self-leadership, grit, and performance.Specifically, self-leadership was selected as an independent variable, two dimensions of grit were selected as mediator variables, and performance was selected as a dependent variable. This structural equation model is based on previous studies.The subjects of this study were middle and high school Taekwondo players, and the survey was collected using the online survey system KSDC (Korean Social-Science Data Center). The sampling method was a non-probability sampling method, convenience sampling method.A total of 367 copies were collected through this process, and 355 copies were used as the final valid samples after excluding the insincere data.Data processing was done with SPSS 23 for frequency analysis, exploratory factor analysis and reliability analysis. Also, AMOS 21 was used for confirmatory factor analysis and structural equation model analysis. The results of the analysis are as follows: First, self-leadership had a positive effect on bothi interest consistency grit and effort persistence grit. Second, it was found that both interest consistency grit and effort persistence grit have a positive effect on performance.Third,self-leadership had a positive effect on performance.