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고속 엔드밀 가공시 가속도 신호를 고려한 가공표면의 시뮬레이션
이기용,강명창,이득우,김정석,Lee, Gi-Yong,Gang, Myeong-Chang,Lee, Deuk-U,Kim, Jeong-Seok 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.2
To obtain precise machined surface and high productivity in machining, high speed end milling has beed studied recently. Though high speed end milling is explicitly effective for precision surface generation geometrically, tool deflection, chatter vibration and frequency characteristics of end milling system deteriorate the theoretical surface. In this study, simulation algorithm and programming method are suggested to simulate machined surface using acceleration signal in high speed end milling. This simulation is conducted by considering vibrational effect of spindle system which was not considered by other investigators. Good agreements were obtained between simulated results and experimental results.
3차원 쉐어렛 변환과 심층 잔류 신경망을 이용한 무참조 스포츠 비디오 화질 평가
이기용,신승수,김형국,Lee, Gi Yong,Shin, Seung-Su,Kim, Hyoung-Gook 한국멀티미디어학회 2020 멀티미디어학회논문지 Vol.23 No.12
In this paper, we propose a method for no-reference quality assessment of sports videos using 3D shearlet transform and deep residual neural networks. In the proposed method, 3D shearlet transform-based spatiotemporal features are extracted from the overlapped video blocks and applied to logistic regression concatenated with a deep residual neural network based on a conditional video block-wise constraint to learn the spatiotemporal correlation and predict the quality score. Our evaluation reveals that the proposed method predicts the video quality with higher accuracy than the conventional no-reference video quality assessment methods.
산소부화된 자유롭게 전파하는 CH<sub>4</sub>/O<sub>2</sub>/N<sub>2</sub>예혼합화염의 화염구조
이기용,남태형,유현석,최동수,Lee, Gi-Yong,Nam, Tae-Hyeong,Yu, Hyeon-Seok,Choe, Dong-Su 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.4
Numerical simulations of freely propagating flames burning stoichiometric CH$_4$/O$_2$/$N_2$mixtures are performed at atmospheric pressure in order to understand the effect of the $O_2$enrichment level on CH$_4$/Air flame. A chemical kinetic mechanism is employed, the adopted scheme involving 54 gas-phase species and 632 forward reactions. The calculated flame speeds are compared with the experiments for the flames established at several $O_2$enrichment level, the results of which is in excellent agreement. As a result of the increased $O_2$enrichment level from 0.21 to 1, the mole fraction of CO in the burred gas is increased. The flame speed and the temperature in the burned gas are also increased, but the thickness of the flame is severely shrunken in the preheat region. The maximum of the calculated EINO is obtained around 0.6 and 0.7 of the $O_2$enrichment level in cases of flames for fuel-lean mixtures.
이기용,하건호,강명창,이득우,김정석,Lee, Gi-Yong,Ha, Geon-Ho,Gang, Myeong-Chang,Lee, Deuk-U,Kim, Jeong-Seok 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.7
A dynamic model for the prediction of surface topography in high speed end milling process is developed. In this model the effect of tool runout, tool deflection and spindle vibration were taken in to account. An equivalent diameter of end mill is obtained by finite element method and tool deflection experiment. A modal parameter of machine tool is extracted by using frequency response function. The tool deflection, spindle vibration chip thickness and cutting force were calculated in dynamic cutting condition. The tooth pass is calculated at the current angular position for each point of contact between the tool and the workpiece. The new dynamic model for surface predition are compared with several investigated model. It is shown that new dynamic model is more effective to predict surface topography than other suggested models. In high speed end milling, the tool vibration has more effect on surface topography than the tool deflection.