• 한국전산구조공학회논문집
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• 제33권4호
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• pp.263-270
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• 2020

본 연구의 대상은 도로 폭이 좁은 시가지에서 굴착공사 시 적용되는 장지간 주형의 연결부이다. 일반적으로 적용되고 있는 연결부에서 상부 플랜지의 단차와 피로균열 등의 문제로 연결부의 신뢰도가 저하된다. 연결부의 결함을 보완하고 안전성을 향상시킨 개선형 연결부를 개발하였다. 유한요소 기반의 상용프로그램(ABAQUS)를 이용하여 개선형 연결부의 거동을 평가하였다. 먼저, 개선형 연결부에 적용되는 고장력 볼트 연결 및 강재와 콘크리트의 합성거동을 구현하기 위한 수치해석 방법을 제안하였다. 비교논문의 실험결과와 수치해석 결과의 비교를 통하여 개선형 연결부를 해석하는데 있어 수치해석 방법의 적합성을 검증하였다. 본 연구에서 제안하는 수치해석 방법을 적용하여 개선형 연결부와 일반형 연결부가 적용된 장지간 주형을 해석하였다. 장지간 주형의 탄소성 거동과 연결부의 응력분포를 수치 해석적으로 비교분석하였다. 개선형 연결부의 도입으로 25%의 압축응력이 감소되며 구조적 성능 개선효과 및 안전성을 확인하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제22권3호
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• pp.75-83
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• 2018

본 연구에서는 일반 버팀보 공법을 개선한 조립식 버팀보 공법을 적용할 때 구조안정성에 대하여 검토하였다. 굴착단계별 가상의 최대 발생 토압력에 대해 좌굴되지 않도록 충분한 강성을 가지는에 대한 안정성검토를 실시하였다. 고강도 조립식 버팀보 공법은 상부플랜지에 일정한 간격으로 볼트 구멍이 천공되어 있는 공법이다. 구조물의 좌굴해석 결과 안전율은 약 5%정도 증가하였고, 발생응력이 허용응력보다 낮기 때문에 버팀보의 구조 안정성은 확보된 것으로 판단된다. 특히 고강도 버팀보 공법을 적용 시 축방향 압축응력은 약 16% 증가한다. 고강도 버팀보 공법은 공사기간을 단축할 수 있으며 추가 부재를 구매할 필요가 없어 경제적이다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1273-1278
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• 2000

Bridge load rating calculations provide a basis for determining the safe load capacity of bridge. Load rating requires engineering judgement in determining a rating value that is applicable to maintaining the safe use of the bridge and arriving at posting and permit decisions. Load testing is an effective means in calculating the rating value of bridge. In Korea, load carrying capacity of bridge is modified by stress modification factor that is determined from comparisons of measured values and analysis results The stress modification factor may be corrupted by vehicle location error that is defined as the gap of test vehicle location between load testing and analysis. In this study, the effects of vehicle location error to structural response and stress modification factor are investigated, and a new method for evaluating stress modification factor is proposed. The random data analysis shows that the proposed method is less sensitive to vehicle location error than the present method.

• 한국자동차공학회논문집
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• 제21권1호
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• pp.137-144
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• 2013

This study analyzes structural analysis with fatigue and natural frequency on ATV knuckle. The maximum equivalent stresses are happened at the end of knuckle in case of model 1, 2 and 3. As these stresses are below the allowable stress, these models can be stable structurally. The fatigue damage possibility at model 1 becomes more than model 2 and 3. Model 2 or 3 has more durability than model 1 at fatigue. As the resonances are happened at the frequency more than 2000 Hz in case of model 1, 2 and 3, there is no resonance possibilities at real driving. Prevention against damage and durability prediction on automotive chassis parts can be effectively improved by applying this study result on knuckle and improving structural strength.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4075-4079
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• 2010

본 논문의 목적은 현재 도기가스, 상하수도 및 화학배관 파이프 등의 플라스틱 배관 공사에서 사용되는 파이프 융착기를 3차원 설계하고 융착 시 발생하는 문제점을 해결하기 위하여 구조해석에 의한 검증작업을 거쳐 구조를 개선한다. 현장에서 파이프 융착 작업 시 융착기 크램프에 크랙이 발생하므로 이를 개선하기 위하여 융착기의 구조를 변경하는 설계치를 제시함으로서 작업의 효율성을 높이고 기술경쟁력을 향상시킨다.

• Computers and Concrete
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• 제11권2호
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• pp.149-167
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• 2013

The complete stress-strain behavior of steel fiber reinforced concrete in compression is needed for the analysis and design of structures. An experimental investigation was carried out to generate the complete stress-strain curve of high-performance steel fiber reinforced concrete (HPSFRC) with a strength range of 52-80 MPa. The variation in concrete strength was achieved by varying the water-to-cementitious materials ratio of 0.40-0.25 and steel fiber content (Vf = 0.5, 1.0 and 1.5% with l/d = 80 and 55) in terms of fiber reinforcing parameter, at 10% silica fume replacement. The effects of these parameters on the shape of stress-strain curves are presented. Based on the test data, a simple model is proposed to generate the complete stress-strain relationship for HPSFRC. The proposed model has been found to give good correlation with the stress-strain curves generated experimentally. Inclusion of fibers into HPC improved the ductility considerably. Equations to quantify the effect of fibers on compressive strength, strain at peak stress and toughness of concrete in terms of fiber reinforcing index are also proposed, which predicted the test data quite accurately. Compressive strength prediction model was validated with the strength data of earlier researchers with an absolute variation of 2.1%.

• 한국가족관계학회지
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• 제22권1호
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• pp.3-22
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• 2017

Objectives: The purpose of this study was to identify the mediating effects of family resilience and depression in a relation between family stress and psychological well-being among middle-aged. Method: The subjects were 409 of men and women between 40 to 59 living in D and G province. They completed the questionnaire on family stress, family resilience, depression, and psychological well-being. Correlation and structural equation models of SPSS 23.0 and AMOS 22.0 were used to examine the relations between the variables. Results: The results are as follows. First, family stress had no significant effect on psychological well-being of middle age men and women, while it directly influenced on family resilience and depression. Second, family resilience and depression had direct influence on psychological well-being. Third, there were significant mediating effects of family resilience and depression in a relationship between family stress and psychological well-being. Conclusions: Family stress has an indirect effect on psychological well-being among middle age men and women mediated by family resilience and depression. The result suggest that psychological well-being influenced by family stress can be improved by enhancing Family Resilience and reducing Depression.

• 한국기계가공학회지
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• 제11권1호
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• pp.125-133
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• 2012

This study aims at structural analysis with fatigue on the shock absorber mount of automobile. Two kinds of mount as original model 1 and reinforced model 2 are applied. Among the cases of nonuniform fatigue loads at both models, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'SAE bracket history' or 'SAE transmission', the maximum fatigue life at model 2 is 5 to 6 times as much as model 1 and the minimum damage at model 2 is decreased 5 to 6 times as much as model 1. In case of 'Sample history' as slow fatigue loading history, the minimum damage at model 2 becomes same as model 1 but the maximum fatigue life at model 2 is decreased more than 17 times as much as model 1. In case of 'Sample History' with the average stress of -$10^4MPa$ to $10^4MPa$ and the amplitude stress of 0MPa to $10^4MPa$, the possibility of maximum damage becomes 3%. This stress state can be shown with 5 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. Safe and durable design of shock absorber can be effectively improved by using this study result on mount frame.

• 한국건축시공학회지
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• 제9권6호
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• pp.169-174
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• 2009

기존의 평면으로 배치된 와이어 메쉬의 단점을 조사하고 이를 개선하기 위한 3차원으로 굴곡한 를 개발하기 위한 타당성을 분석하고자 다양하게 굴곡시킨 경우에 대한 구조해석을 수행하였다. 상부슬래브 전체 및 편측 등분포하중을 재하 한 모든 경우에서 wire mesh 굴곡각도 $45^{\circ}$인 경우가 정모멘트구간 및 부모멘트구간 모두 휨인장응력은 가장 적게 발생되고 횡방향으로 $45^{\circ}$ 굴곡시킨 경우가 전단응력이 가장 적게 발생된다. 변위도 종방향 굴곡각도 $45^{\circ}$인 경우가 변위가 가장 적게 발생된다. 따라서 기존의 평면으로 배치한 와이어 메쉬보다 굴곡시켜 배치하면 휨인장응력, 전단응력, 변위가 줄어들게 되므로 구조적으로 성능이 개선되며 와이어 메쉬를 $45^{\circ}$로 굴곡하는 것이 가장 구조적으로 유리하다.

• 한국자동차공학회논문집
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• 제24권5호
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• pp.504-511
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• 2016

This study investigates the durability of strut bar at car through structural and fatigue analyses. In this study, there are model 1 and model 2 as the analysis subjects. Model 1 is the existed one and model 2 is the improved one added with the reinforced part. Model 1 has the maximum equivalent stress of 165.11 MPa shown intensively at the welding part between the bracket and the bar. This stress is distributed over at the part of model 2 reinforced with this part. In case of fatigue analysis, there are three kinds of fatigue load as SAE bracket history, SAE transmission and sample history. The maximum fatigue life at SAE bracket history among three kinds of fatigue loads has the least value of $3.3693{\times}10^5$ cycles. The maximum fatigue life of model 2 becomes longer than that of model 1. As model 2 has the fatigue damage less than model 1, model 2 has the safety than model 1. As the fatigue durability about the configuration of strut bar is analyzed, it is thought to apply this study result into the real part effectively.