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Laser Surface Texturing을 이용한 STD61강에 대한 마찰특성에 관한 연구
정우영(Woo Young Chung),민준원(Joon Won Min),김상호(Sang Ho Kim),한형욱(Hyung Wook Han),이명호(Meung Ho Rhce),송종호(Jong Ho Song),정원용(Won Young Jeung) 한국트라이볼로지학회 2008 한국트라이볼로지학회 학술대회 Vol.2008 No.11
Laser texturing technology produces shallow dimples that serve as reservoirs for fluid media and trap the wear debris on material faces, so increase the lubrication efficiency of the materials. STD6l steel specimen has been fabricated by using laser texturing method to investigate friction characteristics through gap, depth and diameter. Marking laser system for laser texture showed reasonable results to modify dimple depth and size of steel. On specific lubricant condition. laser textured materials kept longer low friction characteristic than non treated material. After laser texturing, polishing process is positively necessary to remove the spatters attached on the surface. When used on well-controlled dimple surface. the test process results in substantial reductions in friction.
박영석,정원용,Park Young-Seak,Chung Won-Yong 한국융합신호처리학회 2006 융합신호처리학회 논문지 (JISPS) Vol.7 No.2
디지털신호처리에 있어서 신호의 다상분해(polyphase decomposition)는 멀티레이트(multirate) 시스템 구현에 있어서 다양한 용도로 사용된다. 특히 디지털 필터설계 등에 있어서 다채널 신호를 제공함으로써 병열연산을 가능하게 하여 알고리즘의 성능을 개선하는데 특히 유용하다. 일반적으로 다상분해신호는 원신호를 다운샘플링을 위해 데시메이션(decimation)하기 때문에 원신호에 비해 많은 고주파 성분을 포함하여 주파수 대역이 확장되는 경향이 있다. 이러한 성질은 다상분해신호의 활용, 즉 디지털 신호처리 시스템의 구조나 성능에 상당한 제약을 초래한다. 따라서 본 연구에서는 다상분해신호에 대한 완전 대역압축 및 복원 방법을 이론적으로 제시하고 Matlab 시뮬레이션을 통하여 그 유효성을 확인한다. In digital signal processing, the polyphase decomposition of signal has been often used in the implementation of multirate system. Especially, in the design of digital filter and so forth the method in very useful to improve the performance of various algorithms because it provides the multi-channel for paralled processing. Generally, the polyphase-decomposed signals tend to expand the frequency band by including more high frequencies than original signal from decimation for down sampling. This property brings about the significant limitation in the structure or the performance of digital polyphase signal processing system. In this paper we theoretically propose a perfect band compression and reconstruction method for polyphase component signals, then experimentally show its effectiveness through Matlab simulation.
레이저 점선 패턴가공된 금속표면의 윤활조건에 따른 마찰특성에 관한 연구
정우영(Woo-young Chung),김상호(Sang-Ho Kim),한형욱(Hyung-Wook Han),민준원(Joon-Won Min),정원용(Won-Yong Jeung),이명호(Meung-Ho Rhee) 한국레이저가공학회 2010 한국레이저가공학회지 Vol.13 No.2
A high speed laser texturing method that relies on laser scanner conditions, to form pattern shapes with micro-narrow surface detail such as dotted line features is demonstrated and analyzed. For example, this method may be used to piston ring and gear part for automotive. Data on friction characteristics of two laser patterns employed for STD61 steel will be shown. Comparison of pattern depths obtained by repetition overlapping process with laser scanner to the results on friction coefficient will be provide. It will be shown that friction characteristic in dotted line patterns can significantly depend upon interaction with the lubrication and laser pattern conditions. Laser pattern processing into a shallow depth provides only slight improvement in friction, while work into a deep shape indicates a significant improvement.