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영상통화 품질 측정 시 효율적인 동기화를 위한 마크 개발
이원균(Wonkyun Lee),박종빈(Jongbin Park),전병우(Byeungwoo Jeon) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.11
In this paper, we solve the under-estimation problem of PSNR, which is caused by repeated frames, by easily synchronizing original and decoded frames using the proposed marks. The simulation results show that using the proposed algorithm for synchronization not only achieves better computational saving but also reduces the necessary computing time. Moreover, we show experimental results of delays for commercial messenger services using the proposed marks.
Hardware-in-the-loop Simulation of CNC-controlled Feed Drives
이원균(Wonkyun Lee),이찬영(Chan-Young Lee),김주영(Joo-Yeong Kim),송창규(Chang Kyu Song),민병권(Byung-Kwon Min) Korean Society for Precision Engineering 2015 한국정밀공학회지 Vol.32 No.5
Design and application of hardware-in-the-loop simulation (HILS) for design of CNC-controlled machine tool feed drives is discussed. The CNC machine tool is a complex mechatronics system where the complexity results from the software-based controller composed of a variety of functionalities and advanced control algorithms. Therefore, using a real CNC controller in the control simulation has merits considering the efforts and accuracy of the simulation modeling. In this paper challenges in HILS for a CNC controlled feed drive, such as minimization of time delay and transmission error that are caused by discretization of the feed drive model, is elaborated. Using an experimental HILS setup of a machine tool feed drive applications in controller gain selection and CNC diagnostics are presented.
Tactile Display to Render Surface Roughness for Virtual Manufacturing Environment
이동준(Dong-Jun Lee),박재형(Jae-Hyeong Park),이원균(Wonkyun Lee),민병권(Dong-Jun Lee) Korean Society for Precision Engineering 2016 한국정밀공학회지 Vol.33 No.1
In smart factories, the entire manufacturing process from design to the final product is simulated in a virtual manufacturing environment and optimized before starting production. Suppliers and customers make decisions based on the simulation results. Therefore, effective rendering of the information of the virtual products to suppliers and customers is essential for this manufacturing paradigm. In this study, a method of rendering the surface roughness of the virtual products using a tactile display is presented. A tactile display device comprising a 3 x 3 array of individually controlled piezoelectric stack actuators is constructed. The surface topology of the virtual products is rendered directly by controlling the piezoelectric stack actuators. A series of experiments is performed to evaluate the performance of the tactile display device. An electrical discharge machined surface is rendered using the proposed method.
이충성(Choongsung Lee),강보식(Bosik Kang),이원균(Wonkyun Lee) 한국신뢰성학회 2021 신뢰성응용연구 Vol.21 No.4
Purpose: Condensation water, generated with high temperature and humid air, decreases the reliability of electronic devices. Therefore, this paper compares the experimental results of condensation water and the simulation results. Methods: To measure the amount of condensation water, experiments were conducted on a miniature water tank. Antoine and Wagner equations were used to predict the amount of condensation water analytically. Results: On comparison of measured values with those obtained from Antoine equation, a difference of 12.4∼4.8% was measured, while it was 12.1~4.5% in the case of Wagner equation. Conclusion: It is deduced that the reliability period can be shortened by applying various simulations to the design of electronic devices.
조옥현(Ok Hyun Jo),이원균(Wonkyun Lee),이강재(Kang Jae Lee) 대한기계학회 2020 大韓機械學會論文集A Vol.44 No.2
본 논문에서는 3축 공작기계의 디지털 트윈을 구성하고, 이를 이용하여 가공 시간 또는 생산 원가를 줄이기 위한 최적의 가공 조건을 도출하는 방법을 제안하였다. 제어기, 이송계의 모델과 가공 중 발생하는 절삭부하를 예측하기 위한 모델을 도출하고, 이를 통합하여 디지털 트윈을 구축하였으며, 가공실험을 통해 그 정확도를 검증하였다. 검증된 디지털 트윈을 기반으로 유전 알고리즘을 이용하여 제한된 절삭력을 넘기지 않으며 가공 시간 또는 생산 원가 저감을 위한 최적 가공 조건을 도출하고, 실험을 통해 도출된 가공 조건이 적절함을 판단하였다. 또한 디지털 트윈을 이용하여 절삭력 한계 값과 공구 비용 등 최적화 목적 함수에 포함되는 변수가 최적 가공 조건에 미치는 영향을 분석하였다. This study proposes a new method to optimize machining conditions based on a digital twin of the 3-axis machine tool. A digital twin composed of the physical models of a controller, feed drive systems, and cutting force is constructed and evaluated based on machining experiments. A genetic algorithm is utilized to find machining conditions to minimize machining time and production cost based on the digital twin. The optimal feed rate and spindle speed are obtained for each line of the part program when the cutting force is limited. Machining results are presented to demonstrate the effectiveness of the proposed method. Furthermore, the effects of limited cutting force and tool cost on optimal machining conditions are investigated by using the digital twin.