• 소성∙가공
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• 제14권5호
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• pp.444-451
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• 2005

A new extrusion process of the circular section product with helical fins could be developed by rotating extrusion die. The twisting of extruded product is caused by the twisted conical die surface connecting the die entrance section and the die exit section linearly. But, until now, because the process has used fixed extrusion die, it needs high pressure in order to twist billet and form fin shape on the surface of billet. So, during extruding billet, in order not to twist billet, the extrusion die is needed to rotate itself instead of twisting of billet. It is known that it is possible to reduce extrusion load of product with helical fins by analysis and experiments using rotating die. And it is known that, through the extrusion load analysis by $DEFORM^{TM}-3D$ software, optimal rotational velocity of rotating die can be obtained according to reduction ratio of area and twisted angle of die. And experiments and analysis using rotating extrusion die show that the twisted angle of product can be controlled by twisted angle of extrusion helical die and the rotational velocity of extrusion helical die.

• 전산구조공학
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• 제9권4호
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• pp.135-140
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• 1996

박벽개단면을 갖는 단일 형강재는 압축재로 될 수 있는데 예를 들면 트러스에서 복재가 이런 경우이다. 이 때에는 부재의 조립 때문에 발생하는 필연적 편심을 구조설계시에는 보통 무시한다. 그러나 편심의 영향은 부재를 설계할 때, 특히 압축부재의 설계에서는 고려되어야 할 사항이다. 비틀림이나 혹은 휨과 비틀림에 의해서 좌굴을 일으키는 압축재의 임계하중은 지배하는 비분방정식의 해를 구함으로써 결정된다. 본 논문에서는 채널([), 등변앵글(L), 리프채널(C)의 편심변화에 따른 내하력을 도표로 나타내기로 한다. 또한 식이복잡하므로 컴퓨터를 이용하여 계산한 후, 그 결과를 SURFER프로그램을 사용하여 그래프로 표시하였다.

• Journal of Biosystems Engineering
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• 제38권2호
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• pp.163-170
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• 2013

Purpose: The purpose of this study is to provide analysis of physiological, biomechanical responses occurring from the operation to lifting or twist lifting task appears frequently in agricultural work. Methods: This study investigated the changes of physiological factors such as heart rate, heart rate variability (HRV) and biomechanical factors such as physical activity and kinetic analysis in the task of twisting at the waist while lifting. Results: Heart rates changed significantly with the workload. The result indicated that the workload of 2 kg was light intensity work, and the workload of 12 kg was hard intensity work. Physical activity increased as the workload increased both on wrist and waist. Besides, stress index of the worker increased with the workload. Dynamic load to herniated discs was analyzed using inertial sensor, and the angular acceleration and torque increased with the workload. The proposed measurement system can measure the recipient's physiological and physical signals in real-time and analyzed 3-dimensionally according to the variety of work load. Conclusions: The system we propose will be a new method to measure agricultural workers' multi-dimensional signals and analyze various farming tasks.

• 한국공간구조학회논문집
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• 제1권2호
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• pp.75-83
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• 2001

The characteristics of structural behavior for a cable dome shows a strong nonlinearity and very sensitive by the initial imperfection. The instability phenomenon of Geiger-type cable dome structure is generated due to the in-plane twisting near the critical load level. In this study, therefore, the effect of bracing reinforcement resisting to the in-plane twisting is investigated for the Geiger-type model reinforced by bracing. The effect of initial imperfection is also studied because the structural instability phenomenon of shell-like structure is very sensitive according to the initial condition.

• 한국가구학회지
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• 제12권1호
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• pp.39-45
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• 2001

This study was carried out to evaluate the feasibility of using HDF as surface panels as well as core materials for flush door manufacturing. Several core compositions were developed and applied to manufacture door specimens. Core materials were tested under bending load, door manufacturing process was analysed to find better way of using HDF for door manufacturing, and door specimens were tested under bending, twisting and impact loads. From this study, it was concluded that HDF can be used to manufacture quality flush doors. And it was desirable to use light color HDF as surface panels because dark color HDF caused a problem in manufacturing process by shadow shown through finishing veneer. HDF doors were light, and showed good quality and higher resistance against bending twisting and impact loads.

• Wind and Structures
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• 제39권2호
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• pp.101-110
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• 2024

Tall buildings are distinguished by their slenderness, making them sensitive to wind loads. A huge amount of resources is typically dedicated to controlling loads and vibrations caused by wind. Enhancing tall buildings' aerodynamic performance can save a large portion of these expenses. This enhancement can be achieved through aerodynamic optimization that can be tackled either by altering the outer shape of the building locally through modifying the corners (e.g., corner chamfering) or globally through changing the whole form of the building (e.g., twisting). In this paper, a newly developed aerodynamic optimization procedure (AOP) is adopted to enhance tall buildings' aerodynamic performance. This procedure is a combination of computational fluid dynamics (CFD), Artificial Neural Networks (ANN) and Genetic algorithm (GA). An ANN-based surrogate model is used to evaluate the aerodynamic parameters through the optimization procedure to reach a reliable aerodynamic shape. Helical twisting and corner modifications of the buildings are used to reduce the along-wind base moment.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1525-1529
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• 2003

This paper describes the result of carbody load test. The purpose of the test is to evaluate an safety which carbody structure shall be considered fully sufficient rigidity so as to satisfy proper system function under maximum load and operating condition. Carbody material applied a stainless steel and an aluminum alloy, The stainless steel model is the carbody of a motor car which is delivering to KNR line 1 in 2002 and the aluminum alloy model is the carbody of a motor car which is delivering to GWANGJU line 1 in 2003.

• Structural Engineering and Mechanics
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• 제6권6호
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• pp.633-641
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• 1998

Finite element solutions are presented for the optimal design of symmetrically laminated rectangular plates with various types of internal line supports. These plates are subject to a combination of simply supported, clamped and free boundary conditions. The design objective is the maximisation of the biaxial buckling load. This is achieved by determining the fibre orientations optimally with the effects of bending-twisting coupling taken into account. The finite element method coupled with an optimisation routine is employed in analysing and optimising the laminated plate designs. The effect of internal line support type and boundary conditions on the optimal ply angles and the buckling load are numerically studied. The laminate behavior with respect to fibre orientation changes significantly in the presence of internal line supports as compared to that of a laminate where there is no internal supporting. This change in behavior has significant implications for design optimisation as the optimal values of design variables with or without internal supporting differ substantially.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.986-995
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• 2008

This study introduces the testing results of the AL car body which is applied to LRT. The LRT car body is made of aluminum structure materials like a sandwich panel. The static load test was performed to evaluate the structural characteristic and stability of the AL car body. Considering the vertical, compressive, twisting load and 3-point supporting, Bend natural frequency Measurement, Twist natural frequency Measurement type as a testing terms, the structural stability of a car body was evaluated.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1604-1612
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• 2009

This study introduces comparison the testing results of the AL car body which is applied to FSW and GMAW welding method. The car body is made of aluminum structure materials like a sandwich panel. The static load test was performed to evaluate the structural characteristic and stability of the AL car body. Considering the vertical, compressive, twisting load and 3-point supporting, Bend natural frequency Measurement, Twist natural frequency Measurement type as a testing terms, the structural stability of a car body was evaluated.