• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.700-705
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• 2005

This study presents a fatigue line with a plastic rotational angle to a great extent of plastic strain of Low-Cycle-fatigue period, such as earthquake, etc. This fatigue line with a plastic rotational angle is measured and analysed more simply in practice rather than Woehler's fatigue line which is developed in stress variation of the structure. It shows that the slope of fatigue line with a plastic rotational angle is equal to that with plastic strain through the experiments by proving the correlation that the plastic strain ratio is directly proportional to the plastic rotational angle in plastic hinge.

• 한국강구조학회 논문집
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• 제10권2호통권35호
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• pp.221-232
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• 1998

본 연구에서는 지진 등과 같이 소성변형의 범위가 큰 Low-Cycle-Fatigue 범주에서 구조물의 응력변동을 중심으로 사용되는 기존의 피로곡선인 S-N선도 보다 실질적으로 간단하게 측정하여 분석할 수 있는 소성회전각에 의한 피로곡선을 제시하였다. 이는 소성힌지가 생성되는 곳의 소성변형율과 구조물의 소성회전각이 서로 정비례를 이루는 상관관계임을 입증하여, 실험을 통하여 밝혀진 소성변형율의 피로곡선의 기울기와 소성회전각의 기울기가 서로 같은 값을 가짐을 보여 주었다. 이론은 Manson과 Coffin의 변형을 피로곡선을 도입하였고, 실험은 ECCS 주관하에 실시하였으며, 수치해석을 통하여 소성힌지 부위의 위치와 정확한 소성변형율을 산정할 수 있었다.

• 오토저널
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• 제12권2호
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• pp.29-42
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• 1990

Three dimensional frame structures with such nonlinearities as large displacements, medium rotations, plastic hinges and local defects are efficiently analyzed by introducing the nonlinear rotational spring. Formulations are based on the incremental updated Lagrangian descriptions and the virtual work principle, Axial displacement and twisted angle in beam elements are interpolated linearly, while bending displacements are approximated by the Hermite polynomials. The modified are length method is used as a solution method. The moment-angle of rotation relationship obtained analytically or experimentally can be easily incorporated into the solution procedure. Several examples tested show that the present method can be used efficiently in analyzing nonlinear frame structures with plastic hinges or local defect.

• 한국강구조학회 논문집
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• 제23권5호
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• pp.547-555
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• 2011

무보강 상 하부 ㄱ형강 접합부는 중 저층 강골조의 시공에 적합한 부분강접 접합부의 한 형태이다. 무보강 상 하부 ㄱ형강 접합부의 초기회전강성뿐만 아니라 소성휨모멘트 지지능력은 실제 설계 및 시공에 있어서 매우 중요한 인자로 이에 대한 예측이 반드시 필요하다. 따라서 그동안 진행된 무보강 상 하부 ㄱ형강 접합부에 대한 연구는 초기회전강성 및 소성휨모멘트 지지능력에 영향을 미치는 접합부의 기하학적 형상을 변화시키면서 거동양상을 파악하였다. 이 연구에서는 AISC LRFD Spec.에서 정의한 Type A 형태 접합부의 상부 ㄱ형강의 두께 및 고력볼트 게이지 거리를 변수로 하여 접합부 실험을 수행하여 휨모멘트 지지능력을 파악하였고, 이를 바탕으로 소성휨모멘트 지지능력 예측을 위한 해석모델을 제안하고자 진행하였다. 해석모델 적용의 타당성은 타 연구자가 수행한 접합부 실험결과와 비교 검토함으로써 입증하였다.

• 한국강구조학회 논문집
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• 제23권5호
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• pp.595-606
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• 2011

본 연구는 기둥-보 접합부의 강성에 따른 철골 모멘트 골조의 동적특성의 차이를 파악하는데 목적이 있다. 6층의 철골 모멘트 골조를 설계하였으며, 접합부는 DWA (Double Web-Angle Connection), TSW (Top-and Seat-Angle Connection with Double Web-Angle), FEMA(SAC-Test Summary No.28, Specimen ID : UCSD-6) 접합부를 사용하였고, 완전강접합부의 동적거동특성과 상호 비교 검토하였다. 반강접 접합부의 회전강성은 Chen 과 Kishi 에 의해 제안된 3매개변수파워모델을 사용하여 구하였다. 접합부의 회전 강성을 보의 강성으로 나누어 상대강성으로 정의하여 사용하였다. 모든 골조에 대하여 비선형 정적해석(push over analysis), 반복하중 해석 및 시간이력해석을 수행하였다. 각 접합부의 강성에 따른 내진거동은 층간변위, 소성힌지 및 이력 에너지 분배의 항목별로 비교 분석하였다.

• 소성∙가공
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• 제7권4호
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• pp.340-346
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• 1998

A kinematically admissible velocity field is developed for the analysis of twisting of the extruded products with elliptical shapes from round billet. The twisting of extruded product is caused by the lin-early increased rotational velocity from the center on the cross-section of the workpiece at the die exit. In the analysis the rotational velocity in angular direction is assumed by the multiplication of radial distance and angular velocity. The angular velocity is zero at the die entrance. The increase rate of angular velocity is determined by the minimization of plastic work. The results of the analysis show that the angular velocity of the extruded product in creases with the die twisting angle, the aspect ratio of product the friction condition, the reduction of area, and decreases with the die length.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.210-213
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• 1998

A kinematically admissible velocity field is developed for the analysis of twisting of extruded products. The twisting of extruded product is caused by the linearly increased rotational velocity from the center on the cross-section of the workpiece at the die exit. In the analysis, the rotational velocity in angular direction is assumed by the multiplication of radial distance and angular velocity. The angular velocity is zero at the die entrance and is increased linearly by axial distance from die entrance. The increase rate of angular velocity is determined by the minimization of plastic work. The results of the analysis show that the angular velocity of the extruded product increase with the die twisting angle and the aspect ratio of product and friction condition and reduction area and show that angular velocity increases with the decreases in die length.

• Structural Engineering and Mechanics
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• 제54권1호
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• pp.35-54
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• 2015

The performance of a newly generated steel connection known as SidePlateTM moment connection for seismic loading and progressive collapse phenomenon has been investigated in this paper. The seismic evaluation portion of the study included a thorough study on of interstory drift angles and flexural strengths based on 2010 AISC Seismic Provisions while the acceptance criteria provided in UFC 4-023-03 guideline to resist progressive collapse must be satisfied by the rotational capacity of the connections. The results showed that the SidePlate moment connection was capable of attaining adequate rotational capacity and developing full inelastic capacity of the connecting beam. Moreover, the proposed connection demonstrated an exceptional performance for keeping away the plastic hinges from the connection and exceeding interstory drift angle of 0.06 rad with no fracture developments in beam flange groove-welded joints. The test results indicated that this type of connection had strength, stiffness and ductility to be categorized as a rigid, full-strength and ductile connection.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제22권4호
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• pp.397-410
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• 2000

Skeletal class III had been classified by the position of the maxilla, the mandible, the maxillary alveolus, the mandibular alveolus and vertical development. This morphologic approach is simple and useful for clinical use, but it is insufficient to permit understanding of the pathophysiology of dysmorphoses. The author hypothesizes that there are different patterns of mutual relation of the skeletal components which have contributed pathologic equilibrium of skeletal class III. The purpose of this study are threefold: 1) to classify skeletal class III in subgroups, which can show the architectural characteristics of the deformity, 2) to analyse the craniofacial architecture of each subgroup on etio-pathogenic basis, and 3) to characterize and visualize the pattern as a prototype. Materials used in this study were lateral cephalograms of 106 skeletal class III adults, which were analysed with modified Delaire's architectural and structural analysis. Linear and angular measurements of the individual subject were obtained and cluster analysis was used for the subgrouping. Data were evaluated for verification of the statistical significances. The following results were obtained. 1. By the modified Delaire's architectural and structural analysis and cluster analysis, skeletal class III adults were classified into 7 clusters and presented as prototypes, which could show the pathophysiology of the skeletal architecture 2. There was significant relationship in measurement variables of each cluster, which could reflect characteristics of the skeletal pattern of growth. 3. The flexure of cranial base had a close relationship to the anterior rotational growth of the maxilla and contributes to understand the etio-pathology of skeletal class III. 4. The proportion of craniospinal area in cranial depth, craniocervical angle and vertical position of point Om had a close relationship to rotational growth of the mandible and direction of condylar growth. They contribute to understand the etio-pathology of skeletal class III. In summary, the cranium and the craniocervical area must be considered in diagnosis and treatment planning of dentofacial deformity. And the occlusal plane can be considered as a representative which shows the mutual relationships of the skeletal components.

• 한국정밀공학회지
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• 제32권12호
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• pp.1073-1080
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• 2015

A drive shaft is used to transmit torque and rotation through the connection of components of a drive train. Recently, a monobloc drive shaft without welding regions is developed to improve the safety of the drive shaft. The drive shaft bears the shear stress induced by torque. The objective of this paper is to investigate into the structural safety of a monobloc tubular drive shaft subjected to torque. Elasto-plastic finite element (FE) analysis is performed to estimate the deformation behavior of the drive shaft and stress-strain distribution in the drive shaft. Several techniques are used to create finite element (FE) model of the monobloc tubular drive shaft subjected to torque. Through the comparison of the results of FE analyses with those of experiments from the viewpoint of rotational angle, appropriate correction coefficients for different load conditions are estimated. The safety of the tubular drive shaft is examined using the results of FE analyses for different load conditions. Finally, it is noted that the designed tubular drive shaft has a sufficient structural safety.