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자동조립에서 시뮬레이트 어닐링을 이용한 조립순서 최적화
홍대선,조형석,Hong, Dae-Sun,Cho, Hyung-Suck 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.1
An assembly sequence is considered to be optimal when is minimizes assembly cost while satisfying assembly constraints. To derive such an optimal sequence for robotic assembly, this paper proposes a method using a simulated annealing algorithm. In this method, an energy funciton is derived inconsideration of both the assembly constraints and the assembly cost. The energy function thus derived is iteratively minimized until no further change in energy occurs. During the minimization, the energy is occationally perturbed probabilistically in order to escape from local minima. The minimized energy yields an optimal assembly sequence. To show the effectiveness of the proposed method, case studies are presented for industrial products such as an electrical relay and an automobil alternator. The performance is analyzed by comparing the results with those of a neural network-based method, based upon the optimal solutions of an expert system.
골드링을 이용한 완전 밀폐형 어버트먼트 개발 및 성능평가
홍대선(Dae Sun Hong),전용재(Yong-Jae Jeon),이현열(Hyeon-Yeol Lee),이승영(Seung Young Lee) 한국기계가공학회 2016 한국기계가공학회지 Vol.15 No.2
When chewing forces are repetitively applied to a dental implant, gaps are often generated at the interface surfaces between the abutment and the fixture, which results in some deterioration, such as loosening of the fastening screw, dental retraction, and fixture fractures. To cope with such problems, a sealing-type abutment having a number of grooves along the conical-surface circumference was previously developed, and it showed better sealing performance than conventional ones. To enhance the sealing performance, a new model in which a gold ring is inserted into the top groove of the sealing-type abutment is developed in this study. In addition, a manufacturing process is developed, and performance evaluations, such as fatigue and sealing tests, are carried out. The evaluation results show that the gold-ring-inserted sealing abutment yields better performance than conventional ones.
리튬공기전지의 집전체 특성이 사이클 성능에 미치는 영향
홍대선(Dae-Seon Hong),최연지(Yeon-Ji Choi),진창수(Chang-Su Jin),신경희(Kyoung-Hee Shin),송우진(Woo-Jin Song),연순화(Sun-Hwa Yeon) 한국전지학회 2023 한국전지학회지 Vol.3 No.2
리튬공기전의 일반적인 집전체로 사용되는 Ni foam과 GDL(Gas Diffusion Layer)의 성능을 비교하기 위하여 케첸 블랙(Ketjen black)를 활물질로 사용하여 Cells을 제작하였다. 전기화학적 평가 방법으로는 EIS, 방전/충전 사이클 및 충전-방전 전압 차이를 통하여 성능을 조사하였다. 그리고 물리적 특성을 알아보기 위하여 30 사이클 이후 전극 표면을 SEM 분석하였다. 전기화학적 평가 결과 GDL이 Ni foam보다 안정적인 사이클 특성을 나타내었다. 사이클이 안정적인 이유는 표면 분석을 통하여 확인하였다. To compare the performance of Ni foam and GDL(Gas Diffusion Layer) commonly used in Li-Air batteries for current collector, cells were fabricated using Ketjen black as the active material. As part of the electrochemical evaluation, investigations were conducted using techniques such as EIS, discharge/charge cycles, and assessment of Terminal Voltage gap performance. Furthermore, to examine the physical characteristics, the electrode surfaces were subjected to SEM analysis after 30 cycles. The analysis results revealed that the GDL(Gas Diffusion Layer) exhibited more stable cycling characteristics compared to Ni foam. The reason for the stable cycling was confirmed through surface analysis.
중심합성계획법을 이용한 노후 플래너 밀러 주축 스핀들의 역설계에 관한 연구
김홍록(Hong-Rok Kim),정원지(Won-Jee Chung),설상석(Sang-Seok Seol),홍대선(Dae-Sun Hong),공석환(Seok-Whan Gong),이현준(Hyun-Jun Lee),이성원(Seong-Won Lee) 한국기계가공학회 2022 한국기계가공학회지 Vol.21 No.3
Whereas the necessity for recycling and reuse is being emphasized owing to the depletion of resources and waste disposal problems caused by the continuous development of the industry, the importance of remanufacturing has been highlighted recently. Re-manufacturing involves a series of processes in which failed disposal or aging goods are recovered to a state similar to that of a new product. In this regard, machine tools, which are large structures, can achieve the effect of remanufacturing. Among the various elements constituting the machine tool, the main spindle portion that affects the processing precision is critical. Therefore, this study is conducted to derive improvement measures for the main axis of an old Miller planner via reverse engineering and central composite design, which is one of the core processes of remanufacturing.
유전알고리즘을 이용한 18자유도 인간형 로봇의 자세 최적화
최국진(Kook-Jin Choi),홍대선(Dae Sun Hong) 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.10
When a humanoid robot pushes an object with its force, it is essential to adequately control its posture so as to maximize the surplus torque for all joints. For such purpose, this study proposes a method to find an optimal posture of a humanoid robot using a genetic algorithm in such a way that the surplus torque for all joints is maximized. In this study, pushing motion of an 18-DOF humanoid robot is considered. When the robot takes a cooperative motion to push an object, the palms and soles are assumed to be fixed at the object and ground respectively, and are subjected to sense the reaction force from the object and the ground. Then, the torques for all joints are calculated and reflected to fitness function of the genetic algorithm. To verify the effectiveness of the proposed method, a number of simulations with different fitness functions are carried out. The simulation result shows that the proposed method can be adopted to find optimized posture in cooperative motion of a humanoid robot.
Optimization of the Groove Depth of a Sealing-type Abutment for Implant Using a Genetic Algorithm
Hyeon-Yeol Lee(이현열),Dae-Sun Hong(홍대선) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.6
Dental implants are currently widely used as artificial teeth due to their good chewing performance and long life cycle. A dental implant consists of an abutment as the upper part and a fixture as the lower part. When chewing forces are repeatedly applied to a dental implant, gap at the interface surface between the abutment and the fixture is often occurred, and results in some deteriorations such as loosening of fastening screw, dental retraction and fixture fracture. To cope with such problems, a sealing-type abutment having a number of grooves along the conical-surface circumference was previously developed, and shows better sealing performance than the conventional one. This study carries out optimization of the groove shape by genetic algorithm(GA) as well as structural analysis in consideration of external chewing force and pretension between the abutment and the fixture. The overall optimization system consists of two subsystems; the one is the genetic algorithm with MATLAB, and the other is the structural analysis with ANSYS. Two subsystems transmit and receive the relevant data with each other throughout the optimization processes. The optimization result is then compared with that of the conventional one with respect to the contact pressure and the maximum stress. The result shows that the optimized model gives better sealing performance than the conventional sealing abutment.
유연 다물체 동역학 해석을 이용한 4축 이적재 로봇의 주요 부품 선정
박일환(Il-Hwan Park),고아라(A-Ra Go),설상석(Sang-Seok Seol),홍대선(Dae-Sun Hong) 한국기계가공학회 2022 한국기계가공학회지 Vol.21 No.2
Among the various industrial robots, palletizing robots have received particular attention because of their higher productivity in accordance with technological progress. When designing a palletizing robot, the main components, such as the servo motors and reducers, should be properly selected to ensure its performance. In this study, a practical method for selecting the motors and reducers of a robot was proposed by performing the dynamic analysis of rigid-flexible multibody systems using ANSYS and ADAMS. In the first step, the links and frames were selected based on the structural analysis results obtained from ANSYS. Subsequently, a modal neutral file (MNF) with information on the flexible body was generated from the links and frames using modal analysis through ANSYS and APDL commands. Through a dynamic analysis of the flexible bodies, the specifications of the major components were finally determined by considering the required torque and power. To verify the effectiveness of the proposed method, the analysis results were compared with those of a rigid-body model. The comparison showed that rigid–flexible multibody dynamic analysis is much more useful than rigid body analysis, particularly for movements heavily influenced by gravity.