• Journal of Korean Association for Spatial Structures
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• v.4 no.4 s.14
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• pp.55-63
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• 2004

Double angle connections are commonly used for the construction of the low-rise steel framed buildings. Several experimental tests lave been conducted to investigate the effect of the number of bolts on the rotational stiffness of a double angle connection. Several parameters are obtained by performing regression analysis. An analytical model has been introduced to calculate the initial stiffness of a double angle connection in this research.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.128-138
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• 1996

Based on the virtual stiffness model, the stiffness of a grasped object is characterized. Differing from the previous investigations, the effect of grasp force on the stiffness of a grasp is formulated in terms of additional stiffness, which is called additional stiffness in this paper, and it is addressed how this term affects the stability of a grasp. In addition, a method of controlling the stiffness of a grasp is proposed and validated by experiments using a two-fingered robot hand.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.128-130
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• 2011

플로팅 구조물은 파랑하중의 영향에 따라 함체가 변형하게 되며, 이러한 변형이 상부구조물에 영향을 주게 된다. 함체의 강성변화 및 파랑의 주기변화에 따라 해석을 수행한 결과 함체의 강성이 증가할수록 모멘트는 감소하며, 축력에 대한 영향은 미미하다. 함체의 강성이 같다면 파랑의 주기가 길어질수록 모멘트는 증가한다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.398-403
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• 1996

이 논문에서는 지반과 기초를 일반적인 3차원 유한요소로 모델링하고, 유한요소의 바깥영역은 일반적인 모드의 축대칭 유한요소와 축대칭 Hyperelement를 사용하여 전달경계로 모델링하여, 유한요소와 전달경계의 경계에서 두 요소간의 연계에 의하여 기초에서의 동적강성행렬을 구한다. 이를 위하여 3차원 유한요소와 축대칭 요소간의 연계방법을 제안한다. 제시되는 기초의 동적강성행렬은 x,y,z방향의 병진성분과 x,y,z축에 관한 회전성분의 6자유도로 표현된다. 이 논문에서 사용한 3차원 유한요소와 축대칭 요소의 연계 방법의 검증을 위하여 구형기초와 등가의 강성을 갖는 강체원형기초의 동적강성행렬을 구하고 이를 비교하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.23-29
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• 1997

유한요소법을 이용하여 경수로형 핵연료집합체에서 냉각수 유동에 의한 수직 상승력으로부터 핵연료를 지지하는 판형 HDS의 강성도를 수치해석적으로 평가할 수 있는 방법을 제안하였다 I-DEAS code의 8 node brick element를 사용하고 판스프링들간의 간섭 부위에 접촉요소를 사용한 유한요소 모델링 및 해석기법으로 평가한 탄성강성도가 변형 에너지법에 근거하여 유도된 탄성강성도 평가식으로부터 얻은 결과와 잘 일치하고 있어서 제안된 유한요소 모델링 및 해석기법은 판형 HDS의 거동 분석에 유용하게 이용될 수 있다.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.91-98
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• 2015

In order to apply to stretchable electronics packaging, locally stiffness-variant stretchable substrates consisting of island structure were fabricated by combining two polydimethylsiloxane elastomers of different stiffnesses and their elastic moduli were characterized as a function of the width of the high-stiffness island. The low-stiffness substrate matrix and the embedded high-stiffness island of the stretchable substrate were formed by using Dragon Skin 10 of the elastic modulus of 0.09 MPa and Sylgard 184 of the elastic modulus of 2.15 MPa, respectively. A stretchable substrate was fabricated to be a configuration of 6.5-cm length, 0.4-cm thickness, and 2.5-cm width, in which a high-stiffness Sylgard 184 island, of 4-cm length, 0.2-cm thickness, and 0.5~1.5-cm width, was embedded. The elastic modulus of a stretchable substrate was increased from 0.09 MPa to 0.16 MPa by incorporating the Sylgard 184 island of 0.5-cm width to Dragon Skin 10 substrate matrix. The elastic modulus was further improved to 0.18 MPa and 0.2 MPa with increasing the Sylgard 184 island width to 1.0 cm and 1.5 cm, which were in good agreement with values estimated by combining the Voigt structure of isostrain and the Reuss structure of isostress.

• Composites Research
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• v.31 no.4
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• pp.161-170
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• 2018

Cylindrical composite lattice structures are manufactured by filament winding process. The fiber volume fraction non-uniformity and resin rich layers that can occur in the manufacturing process affect the stiffness and strength of the structure. Through the cross-section examination of the hoop and helical ribs, which are major elements of the composite lattice structure, we observed the fiber volume fraction non-uniformity and resin rich layers. Based on the results of the cross-section examination, the stiffness of the ribs was analyzed through the experimental and theoretical approaches. The results show that the fiber volume fraction non-uniformity and resin rich layers have an obvious influence on the rib stiffness of composite lattice structure.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1118-1125
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• 2009

This study, as basic research which was intended to develope the surface reinforcement method using reinforcement material which is applicable to very soft ground in Korea, was aimed at proposing Bearing Capacity Evaluation method for the surface ground improvement method. To that end, a wide width tensile test using geotextile, geogrid and steel bar (substitute for bamboo) and 21 kinds of the laboratory model tests with the end restraint conditions of the reinforcement that comprises the constrained and partially constrained (3 types) conditions were conducted. According to result of tests, Terzaghi's bearing capacity method is adequate to calculate bearing capacity in non-stiff material(geotextile, geogrid). But, It can't adequate to stiff material(bamboo net). So, New bearing capacity method suggest surface reinforcement method of very soft ground which Terzaghi's bearing capacity method modify for effect of stiffness.

• Journal of the Korean Geotechnical Society
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• v.31 no.4
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• pp.31-43
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• 2015

A numerical analysis on the effect of increasing tensile stiffness of the geosynthetics on the soil displacement and pile efficiency was conducted. Parametric studies by changing the stiffness of soft soil, internal friction and dilatancy angles of the embankment material, and flexual stiffness of the composite layer including the geosynthetics were carried out. In general, increasing stiffness of the geosynthetics improves the pile efficiency, whereas the amount of its improvement depends on the condition of parameters. In case of the sufficiently low stiffness of the soft soil or high flexual stiffness of the composite layer including the geosynthetics, a noticeable increase in the pile efficiency can be observed. When the stiffness of the soft soil is very low, the increase in the stiffness of the geosynthetics can significantly reduce the vertical displacement in the piled embankment. When the flexual stiffness of the composite layer is sufficiently high, increasing stiffness of the geosynthetics can greatly improve the pile efficiency.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3D
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• pp.271-278
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• 2010

Semi rigid pavement is a pavement type using advantages of both flexibility of asphalt pavement and rigidity of concrete pavement by infiltrating cement paste into voids of open graded asphalt mixtures. The semi rigid pavement has better smoothness and smaller driving vibration or noise comparing to the concrete pavement, and has smaller permanent deformation and has temperature falling effect comparing to the asphalt pavement. The temperature falling effect were investigated at a semi rigid overlay pavement test section, and the temperature falling and water retaining effects were verified by measuring the temperature and weight of specimens at a housetop. Horizontal and vertical stresses and strains were compared by structural analysis of the semi rigid pavement and asphalt pavement using the Abaquser o, a commercial 3D finite element analysis program. The results were verified by Bisar 3.0, a multi-layered elastic analysis program. Performance of the semi rigid pavement and asphalt pavement were compared by predicting fatigue cracking based on the structural analysis results.