• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1391-1392
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• 2013

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.283-287
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• 2003

In recent years, design of an optimal blank shape is very important for sheet metal forming process in the automobile industry because the raw material cost rate is significant part in the automobile industry. With the design of an optimal blank shape, the engineer can protect a blank from an excessive holding force to improve the quality and reduce the ratio of material scrap. Therefore design of an optimal blank shape is inevitable in sheet metal forming process. However, if it causes a complicated shape of blank, it may be difficult to do the blank layout optimally. In this study, we developed software of optimal blank layout connected with the software of optimal blank shape design which was created in the past by the present authors. And by using these softwares, we would like to present the method in order to get optimal utilization ratio easily and precisely within short time for the sequence of works from design to blank layout.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1513-1518
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• 1996

A force reflecting hand controller can be used to provide more realistic information to the operator of a teleoperation system such as kinesthetic feedback from a slave robot. In this paper, a new design concept of a force reflecting 6-DOF hand controller utilizing the kinematic structure of a Stewart Platform is presented. Based on the optimal design technique of a Stewart Platform, a force reflecting hand controller has been designed and constructed to verify the technical feasibility of proposed design concept. In order to provide an operator with kinesthetic feedback information, a force mapping algorithm based on a reciprocal product of screws has been introduced. Finally, the technical feasibility of the design concept has been demonstrated through some of experimental results of the device under virtual environment on a real-time graphic system.

• 대한의용생체공학회:의공학회지
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• 제17권2호
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• pp.215-220
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• 1996

Impact force and strains induced by impact between the occluder and the struts have been measured with force sensor and strain gages. The maximum reaction force was about 25N, and the calculated impact force on the root of the struts amount about 9-17W. Impact force on the inlet strut is greater than that of the outlet strut, but the strain on the outlet strut is much higher than that of the inlet strut. These values might cause severe damage on the valve in the critical cases. The results of this study may be extended for the analysis of the endurance limit and optimal design of the struts and occluder.

• 한국전산구조공학회논문집
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• 제25권5호
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• pp.375-380
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• 2012

본 연구에서는 선체 블록의 운반 작업 중 발생하는 동적 하중 및 골리앗 크레인의 와이어 로프(wire rope)와 선체 블록간의 동적 접촉력을 고려한 최적 러그 배치 시스템을 설계하고, 다물체계 동역학 커널과 외력 계산 커널을 개발하였다. 다물체계 동역학 커널은 recursive formulation을 이용하여 운동 방정식을 구성하였고, 외력 계산 커널은 비선형 유체 정역학적 힘, 선형 유체 동역학적 힘, 풍력, 계류력을 계산할 수 있다. 개발된 커널의 효용성을 검증하기 위해, 이를 이용하여 와이어 로프와 블록간의 간섭과 이때 작용하는 동적 접촉력을 계산하였고, 마지막으로 계산 결과를 반영하여 러그가 부착된 블록에 대한 구조 해석을 수행하였다.

• Wind and Structures
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• 제36권2호
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• pp.105-120
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• 2023

The present study is performed to find the effect of corner recession on a square plan-shaped tall building. A series of numerical simulations have been carried out to find the two orthogonal wind force coefficients on various model configurations using Computational Fluid Dynamics (CFD). Numerical analyses are performed by using ANSYS-CFX (k-ℇ turbulence model) considering the length scale of 1:300. The study is performed for 0° to 360° wind angle of attack. The CFD data thus generated is utilised to fit parametric equations to predict alongwind and crosswind force coefficients, C_fx and C_fy. The precision of the parametric equations is validated by employing a wind tunnel study for the 40% corner recession model, and an excellent match is observed. Upon satisfactory validation, the parametric equations are further used to carry out multiobjective optimization considering two orthogonal force coefficients. Pareto optimal design results are presented to propose suitable percentages of corner recession for the study building. The optimization is based on reducing the alongwind and crosswind forces simultaneously to enhance the aerodynamic performance of the building.

• Ocean Systems Engineering
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• 제14권2호
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• pp.157-169
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• 2024

The sudden release of water from a dam failure can trigger bores on a flat surface and exert substantial impact forces on structures. This flow poses a high-risk flood hazard to downstream urban areas, making it imperative to study its impact on structures and devise effective energy dissipators to mitigate its force. In this study, a combination of Genetic Algorithm optimization and numerical modeling is employed to identify the optimal energy dissipator. The analysis reveals that a round arc-shaped structure proves most effective, followed by a triangular shape. These shapes offer wide adaptability in terms of structure dimensions. Structures with higher elevation, especially those with round or triangular shapes, demonstrate superior energy dissipation capabilities. Conversely, square-shaped structures necessitate minimal height to minimize impact forces. The optimal width for dissipating energy is found to be 0.9 meters, allowing for effective wave run-up and propagation. Furthermore, the force exerted on structures increases with higher initial water levels, but diminishes with distance from the dam, highlighting the importance of placement in mitigating impact forces.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.1095-1096
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• 2012

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.282-286
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• 2000

In this paper, magneto-rheological(MR) damper is studied for vibration control of large infra structures under earthquake. Generally, active control devices need a large control force and a high power supply system to reduce the vibration effectively. Large and miss tuned control force may induce the dangerous situation such that the generated large control force acts to amplify the structural vibration. Recently, to overcome the weaknesses of the active control, the semi-active control method is suggested by many researchers. Semi-active control uses the passive control device of which the characteristics can be modified. Control force of the semi-active device is not generated from the actuator with power supply. It is generated as a dynamic reaction force of the device same as in the passive control case, so the control system is inherently stable and robust. Unlike the case of passive control, control force of semi-active control is adjusted depending on the measured response of the structure, so the vibration can be reduced more effectively against various unknown environmental loads. Magneto-rheological(MR) damper is one of the semi-active devices. Dynamic characteristics of the MR material can be changed by applying the magnetic fields. So the control of MR damper needs only small power. Response time of MR to the input voltage is very short, so the high performance control is possible. MR damper has a high force capacity so it is adequate to the vibration control of large infra structure. Because MR damper has a nonlinear property, normal control method used in active control may not be effective. Clipped optimal control, modified bang-bang control etc. have been suggested to MR damper by many researchers. In this study, sliding mode fuzzy control(SMFC) is applied to MR damper. Genetic algorithm is used for the controller tuning. To verify the applicability of MR damper and suggested algorithm, numerical simulation on the aseismic control is carried out. Simulation model is three-story building structure, which was used in the paper of Dyke, et al. The control performance is compared with clipped optimal control. The present results indicate that the SMFC algorithm can reduce the earthquake-induced vibration very effectively.

• 대한토목학회논문집
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• 제30권2A호
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• pp.161-168
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• 2010

국내 가동 중 일부 원전의 원자로건물에 부착식 텐던이 설치되어 있고, 부착식 텐던에 대한 유효 긴장력 평가는 이들 원전의 계속운전을 위한 주요 현안으로 부각되고 있다. 따라서, 본 연구에서는 System Identification 기법을 이용한 부착식 텐던의 유효 긴장력 평가를 위하여, SI 기법에 유효한 주요 매개변수의 영향 평가를 수행하고 최적의 매개변수를 도출하였다. 본 연구를 위하여, 원자로건물 벽체의 1/5 축소모형 시험체를 제작하였고, 유효 긴장력과 고유진동수 및 변위와의 상관성을 분석하기 위하여 Impact test, SIMO sine sweep test 및 광섬유센서와 변위계에 의한 휨시험을 수행하였다. 시험결과, 고유진동수와 변위 모두 유효 긴장력과 좋은 상관성을 지니는 것으로 나타나, 이들 매개변수 모두 SI 기법의 입력자료로 활용되어 부착식 텐던의 유효 긴장력 예측이 가능한 것으로 분석되었다.