• Journal of Korean Association for Spatial Structures
• /
• v.6 no.3 s.21
• /
• pp.87-92
• /
• 2006

This paper is a study on the experiment and elasto-plastic discrete limit analysis of reinforced concrete circular cylindrical shell by the rigid-bodies spring model. In the rigid bodies-spring model, each collapsed part or piece of structures at the limiting state of loading is assumed to behave like rigid bodies. The present author propose new discrete elements for elasto-plastic analysis of cylindrical shell structures, that is, a rectangular-shaped cylindrical element and a rhombus-shaped cylindrical element for the improvement and expansion of this rigid-bodies spring model. In this study, it is proposed how this rigid element-bodies spring model can be applied to the elasto-plastic discrete limit analysis of cylindrical shell structures. Some numerical results of elasto-plastic discrete limit analysis and experimental results such as the curve of load-displacement and the yielding and fracturing pattern of circular cylindrical shell under horizontal load are shown.

• Structural Engineering and Mechanics
• /
• v.18 no.3
• /
• pp.343-362
• /
• 2004

Rocking response of rigid bodies with rectangular footprint, freely standing on horizontal rigid plane is studied analytically. Bodies are subjected to simulated single component of horizontal earthquakes. The effect of baseline correction, applied to simulated excitations, on the rocking response is first examined. The sensitiveness of rocking motion to the details of earthquakes and geometric properties of rigid bodies is investigated. Due to the demonstrated sensitivity of rocking response to these factors, prediction of rocking stability must be made in the framework of probability theory. Therefore, using a large number of simulated earthquakes, the effects of duration and shape of intensity function of simulated earthquakes on overturning probability of rigid bodies are studied. In the case when a rigid body is placed on any floor of a building, the corresponding probability is compared to that of a body placed on the ground. For this purpose, several shear frames are employed. Finally, the viability of the energy balance equation, which was introduced by Housner in 1963 and widely used by nuclear power industry to estimate the rocking stability of bodies, is evaluated. It is found that the equation is robust. Examples are also given to show how this equation can be used.

• Computational Structural Engineering
• /
• v.11 no.4
• /
• pp.169-176
• /
• 1998

불연속적 거동이 탁월한 벽식 프리캐스트 구조물을 해석하기 위한 방법으로 유한요소법과 강체요소법 등이 있으나, 이들 해석법은 접합부의 거동을 정확히 반영하지 못하고 있다. 본 연구에서는 패널은 강체적 거동을 하고, 판널과 판널 사이의 접합부는 고체적 거동을 가정하는 강체-고체 복합모델(Coupled Model by Rigid and Solid bodies)에 의한 해석법을 제안하며, 간단한 모델의 예를 통해 검증하였다.

• Journal of Korea Multimedia Society
• /
• v.9 no.5
• /
• pp.554-563
• /
• 2006

We present a linear-time algorithm for treating collision response of articulated rigid bodies in physically based modeling. By utilizing the topology of articulated rigid bodies and the property of linear equations, our method can solve in linear time the system of linear equations that is crucial for treating collision response. We also present several new joint condition equations for articulated rigid bodies composed of various joints.

• Korean Journal of Bronchoesophagology
• /
• v.5 no.2
• /
• pp.159-163
• /
• 1999

OBJECTIVE : To study the management (diagnostic and therapeutic) of esophageal foreign bodies with rigid esophagoscopy. MATERIAL AND METHODS : All 100 patients admitted to the Dankook University Hospital for ingestion of foreign bodies between May 1994 and July 1999. The outcome for each patient was determined by examining hospital records of demographic information, identification of the foreign body and the removal procedure used. RESULTS : Rigid esophagoscopy was performed for suspected foreign bodies in 100 cases an impacted. The most frequent location was the upper third of the esophagus (68%). The most common type of foreign body was fish bones in adult(61%) and coins in children(70%). In 12 patients. flexible endoscopy had failed previously to remove the foreign body and 4 cases were migrated esophageal metal stent in esophageal stenosis. CONCLUSIONS : The rigid esophagoscopy is appropriate techniques for managing esophageal foreign bodies.

• Korean Journal of Bronchoesophagology
• /
• v.15 no.1
• /
• pp.28-34
• /
• 2009

Background and Objectives: Foreign bodies of upper aerodigestive tract are common problem for primary care physicians. Delayed diagnosis or failure of removal might cause fatal problemsand complications. Therefore proper diagnosis and management is imperative. In this study, we described clinical features of upper aerodigestive tract foreign body, and analyzed efficacy of different management modality. Materials and Methods: 250 cases of foreign bodies in the esophagus and trachea, between Jan. 1998 through Jan. 2009 has been retrospectively analyzed. A total of 24 cases and 226 cases had been found each as airway foreign bodies and esophageal foreign bodies. The clinical features are described and treatment outcomes, prognosis, and rate of complications of each management modality have been compared. Results: In airway foreign bodies, ventilating bronchoscopy yielded better results, 19 success out of 19 trials than fiberoptic bronchoscopy, 3 success out of 5 trials. Hospitalization days after removal of foreign body didn't show difference between two treatment modalities, although patients who had ventilating bronchoscopy had gone through general anesthesia. And there was no complication after removal of foreign body. In esophageal foreign bodies, rigid esophagoscope yielded better results, 99% of successful removal rate, compared to the EGD, only 78% of successful removal rate. There was no difference of hospitalization days between two modalities. And complication rate was even low in patients who had done rigid esophagoscopic foreign body removal. Conclusion: In upper aerodigestivetract foreign body. Rapid diagnosis and successful foreign body removal is important. Removal by rigid scope(ventilating bronchoscope, rigid esophagoscope) revealed less failure in both airway and esophageal foreign bodies.

• Journal of Mechanical Science and Technology
• /
• v.18 no.2
• /
• pp.193-202
• /
• 2004

This paper presents a computer method for the dynamic analysis of a system of rigid bodies in plane motion. The formulation rests upon the idea of replacing a rigid body by a dynamically equivalent constrained system of particles. Newton's second law is applied to study the motion of the resulting system of particles without introducing any rotational coordinates. A velocity transformation is used to transform the equations of motion to a reduced set. For an open-chain, this process automatically eliminates all of the non-working constraint forces and leads to an efficient integration of the equations of motion. For a closed-chain, suitable joints should be cut and few cut-joints constraint equations should be included. An example of a closed-chain is used to demonstrate the generality and efficiency of the proposed method.

• Journal of the Korean Society of Industry Convergence
• /
• v.20 no.5
• /
• pp.405-410
• /
• 2017

This paper deals with 3D simulation of industrial robot for automated manufacturing system. In order to evaluate the operational characteristics of the industrial robot system in the worst case motion scenario, flexible - rigid multibody analysis was performed. Then, the rigid body dynamics analysis was performed and the results were compared with the flexible - rigid multibody analysis. Modal analysis was also performed to confirm the dynamic characteristics of the robot system. In the case of the flexible-rigid multibody simulation, only the structural members of interest were modeled as elastic bodies to confirm the stress state. The remaining structural members were modeled as rigid bodies to reduce computer resources.

• Journal of the Ergonomics Society of Korea
• /
• v.8 no.2
• /
• pp.43-47
• /
• 1989

An instrumentation system to measure the pressure between elastic bodies and between an elastic and a rigid body has been developed. The force between elastic bodies can be measured only by Elastric- body pressure Meter. As a standard Elastic-body pressure Meter, Model RCG-24A consists of 24 pick-ups, one switch box and one amplifier and measuring is possible at each of 24 measuring spots by swithing one to the nest using the switch box. The system can be used in various specialized disciplines, such as ergonomics, anthropometry and biomechanics.

• Structural Engineering and Mechanics
• /
• v.54 no.6
• /
• pp.1153-1174
• /
• 2015

Deployable structures have gained more and more applications in space and civil structures, while it takes a large amount of computational resources to analyze this kind of multibody systems using common analysis methods. This paper presents a new approach for dynamic analysis of multibody systems consisting of both rigid bars and arbitrarily shaped rigid bodies. The bars and rigid bodies are connected through their nodes by ideal pin joints, which are usually fundamental components of deployable structures. Utilizing the Moore-Penrose generalized inverse matrix, equations of motion and constraint equations of the bars and rigid bodies are formulated with nodal Cartesian coordinates as unknowns. Based on the constraint equations, the nodal displacements are expressed as linear combination of the independent modes of the rigid body displacements, i.e., the null space orthogonal basis of the constraint matrix. The proposed method has less unknowns and a simple formulation compared with common multibody dynamic methods. An analysis program for the proposed method is developed, and its validity and efficiency are investigated by analyses of several representative numerical examples, where good accuracy and efficiency are demonstrated through comparison with commercial software package ADAMS.