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Thermal Management in Laminated Die System
서자호,Amir Khajepour,Jan P. Huissoon 제어·로봇·시스템학회 2014 International Journal of Control, Automation, and Vol.12 No.4
The thermal control of a die is crucial for the development of high efficiency injection moulds. For an effective thermal management, this research provides a strategy to identify a thermal dynamic model and to design a controller. The neural network techniques and finite element analysis enable modeling to deal with various cycle-times for moulding process and uncertain dynamics of a die. Based on the system identification which is experimentally validated using a real system, controllers are designed using fuzzy-logic and self-tuning PID methods with backpropagation and radial basis function neural networks to tune control parameters. Through a comparative study, each controller’s performance is verified in terms of response time and tracking accuracy under different moulding processes with mul-tiple cycle-times.
Experimental Evaluation of Percussion Performance for Rock-Drill Drifter
서자호,박진선,김흥섭,노대경 한국농업기계학회 2015 바이오시스템공학 Vol.40 No.1
Purpose: The objective of this study was to understand the operating mechanism of the rock-drill drifter, to explain how tosetup an experimental test system and measure the strain of the drifter’s rod, and to evaluate the drifter’s performance withrespect to the impact energy and blow frequency. Methods: The structure of the rock-drill drifter and its operating principleregarding the impact process were analyzed. Static calibration was carried out to calculate the correction factor using adrifter rod as the first step of the experimental test. The impact energy and blow frequency were then calculated based onstrain measurements of the drifter’s rod. Results: Experimental results showed that the tested drifter elicited a blowfrequency of 3330 BPM (Blows Per Minute) and generated impact energy of 170 J/blow. This indicates that the drifter elicitsa higher percussion speed and results in a lower impact energy compared to the hydraulic breaker at the same input power. Conclusions: The study proposed methodologies that deal with the experimental setup and the evaluation of the performanceof the rock-drill drifter. These methodologies can be extensively used for validating and improving the percussion performanceof the drilling equipment.
전지형 크레인 조향제어 알고리즘 개발 및 연성해석 기반의 성능평가
서자호(Jaho Seo),이근호(Geun Ho Lee),오광석(Kwangseok Oh) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.5
본 연구의 목적은 120톤급 전지형 크레인의 조향성능 향상을 위한 제어 알고리즘의 개발이다. 이를 위해 AMESim 소프트웨어를 이용하여 전지형 크레인의 유압조향시스템을 모델링하고, PID 기반의 조향제어용 제어기를 MATLAB/Simulink 환경에서 설계하였다. 설계된 제어기의 성능은 실시간 시뮬레이터를 활용한 유압 및 제어 모델간 연성해석을 통하여 검증하였다. The goal of this study was to develop control algorithms to improve the steering performance of a 120-ton all-terrain crane. To accomplish this, a hydraulic steering system for the crane was modeled using AMESim software, and a PID steering control algorithm was designed in the MATLAB/Simulink environment. The performance of the designed controller was verified through multiphysics co-simulations based on a real-time simulator.
드리프터 유압 해석모델을 활용한 성능격차 유발 인자 접근 사례
노대경,서자호,박진선,박승현,장주섭,Noh, Dae-Kyung,Seo, Jaho,Park, Jin-Sun,Park, James,Jang, Joo-Sup 한국시뮬레이션학회 2014 한국시뮬레이션학회 논문지 Vol.23 No.3
드리프터는 국산화개발에 어려움을 겪고 있는 장비이며, 외국선진사의 제품을 데드카피 하여도 시제품의 성능이 뒤떨어지는 현상이 발생하여 왔다. 본 논문은 천공기의 핵심부품인 드리프터의 해석모델을 활용하여 성능격차를 유발하는 요소를 분석하는 사례를 보여준다. 진행절차는 다음과 같다. 우선, 타격시험을 수행하여 해석모델의 신뢰성을 확보한다. 그리고 해석모델을 활용하여 외국선진사 제품과 시제품의 성능비교그래프를 도출한다. 마지막으로 해석모델의 변수를 분석하여 성능격차를 유발하는 인자에 접근한다. 사용된 소프트웨어는 독일 ITI사에서 개발된 SimulationX이다. Drifter is equipment which is hard to localize. Performance of prototype hasn't performed well compared to product of leading companies even though advanced foreign firm's product were dead copied. This study shows cases of approaching the factor which produces performance gap through drifter hydraulic analysis model which is core component of rock drill. Progression of procedure is following. 1) Securing reliability of the analysis model by comparing impact test result with analysis result. 2) Drawing a graph which indicates performance gap between prototype and drifter of advanced foreign firm by using analysis model. 3) Approaching the factor which produces performance gap with analysing variable of the analysis model. Software used for this analysis is SimulationX.
회전관성의 순환최소자승 추정을 이용한 모델 예견 기반 굴삭기의 충돌회피 알고리즘 개발
오광석,서자호,이근호,Oh, Kwang Seok,Seo, Jaho,Lee, Geun Ho 유공압건설기계학회 2016 드라이브·컨트롤 Vol.7 No.4
This paper proposes a model-prediction-based collision-avoidance algorithm for excavators for which the recursive-least-squares (RLS) estimation of the excavator's rotational inertia is used. To estimate the rotational inertia of the excavator, the RLS estimation with multiple forgetting and two updating rules for the nominal parameter and the forgetting factors was conducted based on the excavator-swing dynamics. The average value of the estimated rotational inertia that is for the minimizing effects of the estimation error was computed using the recursive-average method with forgetting. Based on the swing dynamics, the computed average of the rotational inertia, the damping coefficient for braking, and the excavator's braking angle were predicted, and the predicted braking angle was compared with the detected-object angle for a safety evaluation. The safety level defined in this study consists of the three levels safe, warning, and emergency braking. The analytical rotational-inertia-based performance evaluation of the designed estimation algorithm was conducted using a typical working scenario. The results of the safety evaluation show that the predictive safety-evaluation algorithm of the proposed model can evaluate the safety level of the excavator during its operation.