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배기현,최영규,Bae, Ki-Hyun,Choi, Young-Kiu 한국정보통신학회 2015 한국정보통신학회논문지 Vol.19 No.1
본 논문에서는 이동 로봇의 군집 제어를 위해 퍼지 보상된 PID 제어 시스템을 제안한다. 제어 시스템은 선도-추종기법에 기반한 기구학 제어기와 이동 로봇의 동역학적 영향을 고려한 동역학 제어기로 구성되어 있다. 이동 로봇의 대형 유지를 위해 동역학 제어기는 PID제어기로 구성되었다. 하지만 PID 제어기는 비선형 또는 환경 변화에 취약점을 가진다. 이러한 문제를 보완하기 위해 퍼지 보상기를 추가하였다. 마지막으로 개선된 성능을 보이기 위해 컴퓨터 시뮬레이션을 통해 제안된 제어기를 평가하였다. In this paper, a fuzzy compensated PID control system is proposed for formation control of mobile robots. The control system consists of a kinematic controller based on the leader-follower approach and a dynamic controller to handle dynamics effects of mobile robots. To maintain the desired formation of mobile robots, the dynamic controller is equipped with a PID controller; however, the PID controller has poor performance in nonlinear and changing environments. In order to improve these problem, we applied the additional fuzzy compensator. Finally, the proposed control system has been evaluated through computer simulation to demonstrate the improved results.
연선공정 실험을 통한 이층연 스틸코드의 교정도 예측모델 개발
배기현(Gihyun Bae),허훈(Hoon Huh),이준우(Junwu Lee),이병호(Byungho Lee) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
This paper proposes prediction models for the quality of a double-layer steel cord. Main process parameters were first selected from experiments according to the usage of straightening devices in the stranding machine. The stranding experiments for selected process parameters were conducted based on the experimental table established by the Taguchi method. Prediction models were constructed from the regression analysis with the measured assessment items of a doublelayer steel cord. The prediction models constructed can be utilized as a design guideline effectively for the stranding process design of a double-layer steel cord.
측면충돌 시 소성변형 특성을 고려한 단순 B-필라 모델의 최적설계
배기현(GiHyun Bae),송정한(JungHan Song),허훈(Hoon Huh),김세호(SeHo Kim) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_2
This paper is concerned with the optimum design of the B-pillar assembly induced by the high-speed side impact of the vehicle. In order to simulate the deformation behavior of the B-pillar assembly, the simplified finite element model of a B-pillar and a moving deformable barrier are developed based on results of the crash analysis of the full vehicle model. In order to optimize the deformation shape of B-pillar, S-shaped deformation is targeted for guaranteeing the reduction of injury level of the passenger dummy in the crash test. Tailor welded blank is adopted in the simplified B-pillar model to control the deformation shape of B-pillar assembly. The thickness distribution of each part which constitutes the simplitied mode is initially selected as a design parameter. Important design parameters which have effects on the deformation mechanism are selected with sensitivity analysis based on the design of experiment technique. The objective function is constructed so as to minimize the weight and lead to the S-mode deformation shape. The results in this paper fully show that the design criterion of B-pillar model can be simply applied to the part design at the trial design stage for confronting the side impact test such as US-SINCAP and EURO-NCAP.
초기 변형률 및 변형률 속도에 따른 차체 강판의 인장/압축 경화 거동
배기현(Gihyun Bae),허훈(Hoon Huh) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
This paper investigates the effect of the pre-strain and the strain rate on the tension/compression hardening behavior of auto-body steel sheets. To conduct the tension/compression test of auto-body steel sheets, a spring-loaded clamping device was adopted to suppress buckling of specimens. Tension/compression hardening curves was obtained by correcting the friction and biaxiality due to the clamping force during tests. From the hardening curves, the hardening behavior of auto-body steel sheets was compared carefully with respect to the pre-strain and the strain rate. The Bauschinger ratio and the transient behavior in the compression state were quantitatively compared to explain effectiveness of the pre-strain and the strain rate.
드로우비드 저항력과 수직력의 유한요소해석 기반 예측모델
배기현(Gihyun Bae),허훈(Hoon Huh),박성호(Sungho Park) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper deals with the simulation-based prediction model to predict the restraining force and the normal force of draw-beads in sheet metal forming process. The modified DOE method is newly proposed in order to construct the prediction model for the equivalent draw-bead and the finite element analysis is utilized to calculate equivalent draw-bead forces in each design case. The reliability of the finite element analysis is verified by comparing with the experiment. To increase the accuracy of prediction models, a special technique is applied for normalizing the estimated force in each design case. Finally, the accuracy of constructed prediction models is verified by comparing the predicted result with the experimental result. It demonstrates that the simulation-based prediction model can provide accurate equivalent draw-bead forces. The constructed prediction model can not only provide the restraining and the normal force conveniently with respect to the draw-bead design for the simulation of sheet metal forming process, but also be utilized to determine the dimension of draw-beads at actual die design.
배기현(G. H. Bae),허훈(H. Huh),이준우(J. W. Lee),이병호(B. H. Lee) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
This paper deals with an evaluation method of a single-layer steel cord using the finite element analysis during the stranding process. The residual stress distribution of a drawn wire and the shape of a single-layer steel cord before the roller straightening process are investigated carefully for the accurate description of irregularities of a single-layer steel cord. Simulations of a twisting process and two roller straightening processes are performed with a simplified simulation method. From simulations, the steel cord shape and assessment items of the steel cord quality are measured before and after the roller straightening process. The simulation-based evaluation method developed can provide the specific information of the role of straightening devices to the steel cord quality. It also can be utilized for an optimum design of the stranding process for the reduction of the time and cost.
배기현(Gihyun Bae),송정한(Junghan Song),허훈(Hoon Huh),김세호(Seho Kim),박성호(Sungho Park) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Draw-bead is applied to control the material flow in sheet metal forming process and improve the product quality by providing sufficient draw-bead restraining force (DBRF). However, actual die design depends mostly on the trial-and-error method without the accurate prediction of DBRF and the normal force. Die design with the predicted value of them can be utilized effectively to reduce the cost and time. In order to construct a prediction model, process parameters, which affects significantly to DBRF and the normal force, are selected as design variables. At first, the prediction model without considering the effect of BHF is constructed using the Box-Behnken design which is the most representative DOE method. Results obtained from finite element analysis are approximated with the second order regression model. It provides the maximum value of DBRF and the normal force because the male bead fully presses down the sheet. After that, the variation of DBRF with respect to the change of BHF is approximated with the first order regression model by adopting the fractional factorial design. It provides the equation for the scale factor with respect to the change of process parameters. Using two equations, DBRF can be obtained in general sheet metal forming process. To verify the reliability of the prediction model, results obtained from the prediction model are compared with them obtained from finite element analysis.
배기현(G. H. Bae) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.10
This paper evaluates performance of anisotropic yield function to approximate the uni-axial hardening behavior with respect to the loading angle from the rolling direction. Three yield functions, such as Hill48, YJd89 and Yld2000-2d, are selected to approximate the anisotropic hardening behavior. The test material is 340ES steel sheet with the thickness of 0.65 ㎜. The results show that more advanced material model is required to describe the anisotropy change with the increase of the plastic strain.