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다양한 기하학적 형상을 갖는 층간 분리된 복합신소재 적층구조의 동적 불안정성
이상열,장석윤,Lee, Sang-Youl,Chang, Suk-Yoon 한국복합신소재구조학회 2010 복합신소재구조학회논문집 Vol.1 No.1
The dynamic instability analysis of delaminated composite structures subjected to in-plane pulsating forces is carried out based on the higher order shell theory of Sanders. In the finite element (FE) formulation, the seven degrees of freedom per each node are used with transformations in order to fit the displacement continuity conditions at the delamination region. The boundaries of the instability regions are determined using the method proposed by Bolotin. The numerical results obtained for skew plates and shells are in good agreement with those reported by other investigators. The new results for delaminated skew plate and shell structures in this study mainly show the effect of the interactions between the radius-length ratio and other various parameters, for example, skew angles, delamination size, the fiber angle of layer and location of delamination in the layer direction. The effect of the magnitude of the periodic in-plane load on the instability regions is also investigated.
미시역학적 접근 방법에 의한 복합소재 적층 쉘 구조의 유한요소 변위 및 응력해석
이상열,Lee. Sang-Youl 한국방재학회 2014 한국방재학회논문집 Vol.14 No.1
본 연구는 복합소재 적층 쉘 구조에 대하여 마이크로 역학 접근방법에 의한 섬유의 함침비율 변화에 따라 탄성계수를 예측하고 매크로 역학 기반으로 정적 거동 특성을 분석하였다. 본 연구에서 제시하는 멀티 스케일 접근법에 의한 유한요소 모델은 해석의 정확성과 재료들 간의 상관관계를 상세하고 정확이 보여준다는 장점이 있다. 수치해석은 적층 갯수, 적층배열, 섬유함침비율의 변화에 따른 최대 변위 및 응력 변화를 분석하는데 중점을 두고 있다. 수치예제로부터 섬유와 모재의 재료비율은 거시적 구조 거동 특성에 중요한 영향을 주고 있음을 알 수 있었다. 본 연구는 변위 및 응력에 영향을 미치는 최적의 섬유와 모재 재료비율을 상세 분석하였으며, 해석 결과는 건설용으로서의 복합소재 기둥구조가 경제적이면서 우수한 구조 성능을 만족하도록 설계하는데 기여할 수 있을 것으로 기대된다. This study carried out finite element deflection and stress analysis of laminated composite shells, which is based on the micro-mechanical approach for different fiber-volume fractions. The finite element (FE) models for composite structures using multi-scale approaches described in this paper is attractive not only because it shows excellent accuracy in analysis but also it shows the effect of the material combination. The FE model is used for studying static behaviors of laminated composite shells for various fiber-volume fractions. In particular, new results reported in this paper are focused on the significant effects of the fiber-volume fraction for various parameters, such as fiber angles, layup sequences, and length-thickness ratios. It may be concluded from this study that the combination effect of fiber and matrix, largely governing the structural performance of composite structures, should not be neglected and thus the optimal combination could be used to design such civil structures.
가상현실 게임을 이용한 4주간 훈련이 노인의 균형 및 보행 능력과 우울증에 미치는 효과
이상열,이수경,김용훈,채정병,Lee, Sang-Yeol,Lee, Su-Kyung,Kim, Young-Hoon,Chae, Jung-Byung 대한고유수용성신경근촉진법학회 2012 PNF and Movement Vol.10 No.2
Purpose : This study investigated the effect of 4 weeks training of virtual reality game on balance and gait ability, depression of elderly people. Methods : The subjects of this study were 12 elderly people over 65 age. The subjects were treated by training using virtual reality gam (during 60 minutes, 3 times a week for 4 weeks). The results of the experiment were analyzed using paired T-test along with averages and standard deviations as the statistical methods for data analyses. Results : In comparison of depression, gait and balance ability between pre-test and post-test, there were statistically significant differences. Conclusion : Our study finding indicate that training using virtual reality game could improve balance and gait ability, depression in elderly people. According to our study, training using virtual reality game is judged to be used for elderly people with gait and balance problems, depression to prevent fall down.
이상열,Lee, Sang-Yeol 대한물리치료과학회 2015 대한물리치료과학회지 Vol.22 No.1
Purpose : The purpose of this study is to introduce the necessity of introduction and to proposal the methods of introduce for animal physical therapy in Korea. Method : This study is a literature study with books, article and the information through every route for introduction of animal physical therapy in Korea. Results : Animal physical therapy should be introduced to Korea with global trend. For this, it should be need academic exchanges of veterinary and physiotherapy. And there is an urgent need for an educational framework and an institutional framework. And physiotherapist requires preparation and understanding of the animal anatomy. Conclusion : There is an urgent need for an animal physical therapy to welfare and medical benefit of Korean animal companion. The physiotherapist should be prepare educational framework, institutional framework and clinical strategy.
불완전 동적 데이터로부터 복합신소재로 보강된 교량의 함수기반 역해석에 의한 성능 평가
이상열,노명현,Lee, Sang-Youl,Noh, Myung-Hyun 한국복합신소재구조학회 2010 복합신소재구조학회논문집 Vol.1 No.2
This work examines the identification of stiffness reduction in damaged reinforced concrete bridges under moving loads, and carries out the performance assessment after repairing using advanced composite materials. In particular, the change of stiffness in each element before and after repairing, based on the Microgenetic algorithm as an advanced inverse analysis, is described and discussed by using a modified bivariate Gaussian distribution function. The proposed method in the study is more feasible than the conventional element-based method from computation efficiency point of view. The validity of the technique is numerically verified using a set of dynamic data obtained from a simulation of the actual bridge modeled with a three-dimensional solid element. The numerical examples show that the proposed technique is a feasible and practical method which can inspect the complex distribution of deteriorated stiffness although there is a difference between actual bridge and numerical model as well as uncertain noise occurred in the measured data. 본 연구는 차량 이동하중을 받는 손상된 콘크리트 슬래브교량의 강성저하를 규명하고, 복합신소재를 사용하여 보강 후 성능평가를 수행한다. 특히 마이크로 유전알고리즘에 의한 역해석에 기반하여 보강 전 후 각 요소에서의 강성변화를 수정된 2차변수 Gaussian 분포함수를 사용하여 정식화하였다. 본 연구에서 제안한 방법은 기존의 요소기반 접근 방식에 비하여 수치해석적인 관점에서 효율성을 갖는다. 개발한 알고리즘은 3차원 솔리드 요소를 사용하여 모델링한 교량의 동적 거동 시뮬레이션으로부터 계측한 데이터를 사전정보로 사용하여 검증하였다. 몇 가지 수치예제는 본 연구에서 개발한 방법이 실제교량과 수치모델간의 차이로 인한 오차 및 노이즈 등으로 인한 동적 계측치 오류 등이 고려되었음에도 강성분포 추정 및 성능 평가를 효율적으로 수행함을 보여준다.