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고출력 다이오드 레이저를 이용한 SKD11 표면 열처리 특성
최성대,정선환,양승철,김잠규 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-
An experimental investigation with high power diode laser system was carried out to study the effect of surface heat treatment on the SKD11. The surface heat treatment characteristics of the laser beam were evaluated using hardness tests, optical microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy(EDS). Results indicated that the Hardness were changed by beam size, focal length, feed rates. The micro grain structure was observed retained austenite grain at hardened zone and globular cementite grain at fine grain zone and base metal zone by optical microscopy. The intensive X-ray diffraction patterns of (110)-(200)-(211) was detected on the surface and the hardened surface intensity level was bigger than the unhardened surface. The intensive X-ray diffraction patterns of (110)-(200)-(211) was detected hardened surface and the hardened surface distributed plenty of carbon density than metal zone.
퍼지 제어기를 이용한 영구자석 교류전동기의 센서리스 속도제어
최성대,고봉운,김낙교 대한전기학회 2004 전기학회논문지 D Vol.53 No.6(D)
This paper proposes a speed estimation method using FLC(Fuzzy Logic Controller) in order to realize the speed control of PMAM(Permanent Magnet AC Motor) with no speed sensor. This method uses FLC as a adaptive laws of MRAS(Model Reference Adaptive System) and estimates the rotor speed of PMAM with a difference between the reference model and the adjustable model. Speed control is performed by PI controller with the estimated speed . The experiment is executed to verify the propriety and the effectiveness of the proposed system.
최성대,鈴木 裕土,秋田 貢一,三澤 啓志 金烏工科大學校 2000 論文集 Vol.21 No.-
X-ray stress measurements of a single crystal silicon were carried out using characteristic X-rays. The χy-oscillation method was used as the oscillation method of a specimen for obtaining a perfect diffraction profile. Applied stress measurements of a single crystal silicon were carried out using characteristic X-rays. The stresses in three steps were applied on a specimen using a four-point bending device. The diffraction angles of three different diffraction planes were measured in each step using a φ800 ㎛ collimator, and the stresses were calculated from the peak shift. The measured stresses agreed well with the applied stresses evaluated using a strain gage. Therefore, the possibility of X-ray stress measurements of a single crystal was confirmed.
최성대,정선환,김잠규,김우재,김용선 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-
At a point time, when demand is gradually increasing on LCD and PDP market all over the world, demand on glass which is key part of LCD and PDP is increasing, too. Hence, glasses are being cut by requested size for satisfaction on demands, the remain glass is making problems. This study is for designing installation of handling these remained glasses effectively and easily.
최성대,정선환,김기만,전재목,노영진 한국기계가공학회 2005 한국기계가공학회지 Vol.4 No.1
The localization of manufacturing technique development is actualizing for low cost with supplies of display devices. We need more high cutting technique because consumers want flat glasses of various sizes. Recently, most general two methods are normal wheel cutting and laser cutting, but both of them have some faults. First, the wheel cutting has cracks and sharp edges of sections. Second, it is easy for laser cutting to cut curved lines. however, it has thermal damage and low traverse speed. I suggest a new cutting method by high-wave frequency vibration wheel cutting(HFVC), which is good for quality improvement. Vertical cracks and crack depth is observed, after HFVC. When the average of the crack depth is 30㎛ and the average of the wallner liner depth is 200㎛, it has the most high quality of the sections in this experiment. As a result, when we consider between the normal wheel cutting method and the HFVC method, the latter has low cracks and good quality.
최성대,김기만,정선환,권현규,전재목,노영진 한국기계가공학회 2005 한국기계가공학회지 Vol.4 No.3
This research presents a modeling and a manufacturing method of screw flow meter. This paper introduces the efficient design and manufacturing method of screw type flow meter using reverse engineering and test technology. The methods introduced this paper utilize the reverse engineering that is increasing accuracy of modeling and manufacturing of reverse model. And then it can be used in performance test with hydraulic test equipment. Hence this can be used in the basic document for development of the quite accurate flowmeter.
최성대,三澤啓志 금오공과대학교 산업기술개발연구원 2001 産業技術開發硏究 Vol.17 No.-
Fatigue crack growth tests were carried out using high manganese cast steel under constant amplitude loading. Average crystal grain sizes of the material are 200㎛ and 1000㎛. For this material, △Kth is about 8MPa√m which is quiet large as compared to the general structural steels and the crack growth rate is lower than the general structural steels especially in the low △K regsion. The reason of this behavior is crack closure due to fracture surface roughness and fretting oxide. The relationship between da/dN and the △Keff was represented by narrow band regardless of the stress ratio.