• Structural Engineering and Mechanics
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• v.63 no.6
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• pp.809-824
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• 2017

The accurate evaluation of wind characteristics and wind-induced structural responses during a typhoon is of significant importance for bridge design and safety assessment. This paper presents an expectation maximization (EM) algorithm-based angular-linear approach for probabilistic modeling of field-measured wind characteristics. The proposed method has been applied to model the wind speed and direction data during typhoons recorded by the structural health monitoring (SHM) system instrumented on the arch Jiubao Bridge located in Hangzhou, China. In the summer of 2015, three typhoons, i.e., Typhoon Chan-hom, Typhoon Soudelor and Typhoon Goni, made landfall in the east of China and then struck the Jiubao Bridge. By analyzing the wind monitoring data such as the wind speed and direction measured by three anemometers during typhoons, the wind characteristics during typhoons are derived, including the average wind speed and direction, turbulence intensity, gust factor, turbulence integral scale, and power spectral density (PSD). An EM algorithm-based angular-linear modeling approach is proposed for modeling the joint distribution of the wind speed and direction. For the marginal distribution of the wind speed, the finite mixture of two-parameter Weibull distribution is employed, and the finite mixture of von Mises distribution is used to represent the wind direction. The parameters of each distribution model are estimated by use of the EM algorithm, and the optimal model is determined by the values of $R^2$ statistic and the Akaike's information criterion (AIC). The results indicate that the stochastic properties of the wind field around the bridge site during typhoons are effectively characterized by the proposed EM algorithm-based angular-linear modeling approach. The formulated joint distribution of the wind speed and direction can serve as a solid foundation for the purpose of accurately evaluating the typhoon-induced fatigue damage of long-span bridges.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.8
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• pp.761-766
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• 2010

The goal of this study is to analysis natural frequency for different static postures of human leg. To perform this research human leg is modeled by multi-body modeling for the musculoskeletal system. This leg model has biarticular muscles which acting on two joints and the muscles represents some of the major muscles, such as hamstring, of the upper and lower limbs. To obtain each static equilibrium position energy method is employed and to analysis natural frequency linearization method for constrained mechanical system is employed. Static equilibrium position depends on some parameter or condition such as hamstring stiffness or external force. Making a change these parameter the aim of this research can be performed.

• Geomechanics and Engineering
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• v.14 no.4
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• pp.325-336
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• 2018

Deformation of rock masses is not only related to rock itself, but also related to discontinuities, the latter maybe greater. Study on crack propagation at discontinuities is important to reveal the damage law of rock masses. DDARF is a discontinuous deformation analysis method for rock failure and some modified algorithms are proposed in this study. Firstly, coupled modeling methods of AutoCAD-DDARF and ANSYS-DDARF are introduced, which could improve the modeling efficiency of DDARF compared to its original program. Secondly, a convergence criterion for automatically judging the computation equilibrium is established, it could overcome subjective drawbacks of ending one calculation by time steps. Lastly but not the least, relationship between the super relaxation factor and the calculation convergence is analyzed, and reasonable value range of the super relaxation factor is obtained. Based on these above modified programs, influences on crack propagation of joint angle, joint parameters and geo-stresses' side pressure are studied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.774-775
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1377-1378
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• 2011

• Architectural research
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• v.13 no.4
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• pp.53-60
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• 2011

Damage detection algorithms based on a one-dimensional beam model can detect damage within a beam span caused by flexure only but cannot detect damage at a joint with prescribed boundary conditions or at the middle part of a beam section where the neutral axis is located. Considering the damage at a welded joint of beam elements in steel structures and modeling the damage with twodimensional plane elements, this study presents a new approach to detecting damage in the depth direction of the joint and beam section. Three damage scenarios at the upper, middle, and lower parts of a welded joint of a rectangular symmetric section are investigated. The damage is detected by evaluating the difference in the receptance magnitude between the undamaged and damaged states. This study also investigates the effect of measurement locations and noise on the capability of the method in detecting damage. The numerical results show the validity of the proposed method in detecting damage at the beam's welded joint.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.202-209
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• 2007

Vehicle body frame stiffness affects the dynamic and static characteristics. Vehicle frame structural performance is greatly affected by crossmember and joint design. While the structural characteristics of these joints vary widely, there is no known tool currently in use that quickly predicts joint stiffness early in design cycle. This paper presents the joint design factors affecting on low frequency vibration. The joint factors are joint panel thickness, section property, flange width and weld point space. To study the effect on vehicle low frequency vibration, case studies for these factors are performed. And Sensitivity analysis for section property is performed. The result can present design guide for high-stiffness vehicle.

• Journal of the Korean Society of Radiology
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• v.6 no.4
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• pp.299-303
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• 2012

Shoulder MRArthrography was performed to get an accurate diagnosis about complex anatomical structure in shoulder joint. We carried out how the changes of anatomical rotations in shoulder joint could bring certain diagnosis effects on MRI images for various shoulder humerus positions; Neutral position, Internal rotation position and External rotation position. In addition, we prepared an aid tool in oder to maintain the right posture of a patient. This aid tool was made by adapting Modeling Design Program. By virtue of this aid, we obtained the following result. Shoulder MR Arthrography by the External rotation position for anatomical structure diagnosis was the most suitable in diagnostic evaluations of important anatomical structures in shoulder joint such as Biceps tendon, Supera-spiatus tendon, Sub-scapularis tendon, Labrum and Sub-acromial space.

• Tunnel and Underground Space
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• v.8 no.3
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• pp.200-208
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• 1998

This research is intended to investigate the behavior of the jointed rock under various loading conditions: static or dynamic load. The distributed state concept (DSC) is based on the idea that the response of the joint can be related to and expressed as the response of the reference states : relative intact (RI) and fully adjusted (FA) states. In the DSC, an initially RI joint modifies continuously through a process of natural self-adjustment, and a part of it approaches the FA state at randomly disturbed locations in the joint areas. In this study, based on the DSC concept, RI state, FA state, and disturbance function (D) are defined for characterizing the behavior of rock joint. From the results of this research, it can be stated that DSC model is capable of capturing the physical behavior of jointed rock such as softening and hardening and considering the size of joint and roughness of joint surface.

• Korean Journal of Computational Design and Engineering
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• v.18 no.1
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• pp.10-20
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• 2013

The Yoon Jeung residence is a well-known and prototypical aristocratic house example showing typical and interesting characteristics of the traditional houses in the middle region of Korea. When it comes to understanding the architectonic characteristics of a Korean traditional house, it was not easy to actually capture the compositional and/or constructional knowledge of the building even though it is a wooden building with many wooden members showing their compositional relations. Now with the help of the BIM tool, the Building Information Modeling tool, we could actually be able to compare and analyze each member and their compositional relations. In this paper we examine the unique traditional composition method used in extending the building's structural sections utilizing the bended-joint characteristics of traditional buildings with exemplar case of the Yoon Jeung residence. Thereby we examine those relationships among three major compositional parts namely the plan based spatial compositions, the upper wooden compositions and the roof forms so as to specify the building's typical characteristics with reasonably acceptable causes. The inner and outer block of the residence are handled with their bended-joints with more detailed knowledge of categorization by way of joint relationships among members.