마이크로 열소자 제작을 위한 고세장비 금속채널의 레이저 가공

오광환,이민규,정성호,Oh, Kwang-Hwan,Lee, Min-Kyu,Jeong, Sung-Ho 한국광학회 2006 한국광학회지 Vol.17 No.5

본 연구에서는 레이저유도 에칭기술을 이용한 스테인레스강의 고세장비 미세채널 제조에 대하여 기술한다. 공정 변수 최적화와 반복에칭을 통하여 높은 세장비를 갖는 미세채널을 제조하였으며 제조된 미세채널은 레이저출력과 에칭용액의 농도를 적절하게 조절함으로써 U 형상과 V 형상 사이의 단면 구조를 가지며 열변형이 없는 우수한 표면 형상을 보였다. 채널과 채널 사이의 간격은 $150{\mu}m$ 또는 그 이하이며 $15{\sim}50{\mu}m$ 범위의 폭을 갖는 10 이상의 고세장비 미세채널이 제조되었다. 레이저출력, 레이저초점의 이송속도, 에칭용액의 농도 등의 공정 변수들이 제조된 채널의 폭, 깊이 그리고 단면 형상에 미치는 영향에 대하여 자세히 보고한다. A fabrication method fur high-aspect-ratio microchannels in stainless steel using laser-assisted thermochemical wet etching is reported in this paper. The fabrication of deep microchannels with an aspect ratio over ten is realized by applying a multiple etching process with an optimization of process conditions. The cross-sectional profile of the microchannels can be adjusted between rectangular and triangular shapes by properly controlling laser power and etchant concentration. Excellent dimensional uniformity is achieved among the channels with little heat-affected area. Microchannels with a width ranging from 15 to $50{\mu}m$ can be fabricated with an aspect ratio of ten and a pitch of 150 m or smaller. The effects of process variables such as laser power, scan speed, and etchant concentration on the fabrication results, including etch width, depth, and cross-sectional profile are closely examined.

피로균열진전에 따른 304강의 음향방출 거동

오광환(Kwang Hwan Oh),정창규(Chang Kyu Jung),양유창(Yoo Chang Yang),한경섭(Kyung Seop Han) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4

Acoustic emission behavior during fatigue crack growth test was investigated under various loading<br/> condition. To describe the acoustic emission activity, counts rate (dh/dn) was related with SIFR (stress<br/> intensity factor range, DK). Results indicated that SIFR could be divided into two parts according to its<br/> relationship with counts rate. For DK<25MPa m , counts rate was increased as the SIFR increased. However,<br/> for values greater than 25MPa m , decreasing behavior was shown. This behavior of counts rate corresponding<br/> SIFR was keeping the same trend regardless of load range or crack length. Acoustic emission response to the<br/> single overload was sudden drop and slow recovery in counts rate like crack growth retardation. Under<br/> variable loading condition, counts rate of each loading block was same as that of constant amplitude loading.<br/> Overall experimental data was somewhat scattered since sensitive characteristics of acoustic emission method.<br/> However, these empirical relations indicated that counts rate was uniquely correlate with single parameter,<br/> SIFR.

섬유/입자 혼합보강 금속복합재료의 피로균열 진전거동

오광환(Kwang-Hwan Oh),양유창(Yoo-Chang Yang),한경섭(Kyung-Seop Han) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.8

The effects of short fiber and particle hybrid reinforcement on fatigue crack propagation behaviors in aluminum matrix composites have been investigated. Single and hybrid reinforced 6061 aluminum containing same 20 Al₂O₃ volume % with four different constituent ratios of short fibers and particles were prepared by squeeze casting method and tested to check the near-threshold and stable crack growth behavior. The fatigue threshold of the composites increased with portion of particle contents and shows the superior crack resistance in low stress intensity range. In stable crack growth region, the slop of Paris' Law which indicating the crack growth rate was independent of microstructure. After allowing for crack closure, the differences in crack propagation rate among the composites were significantly diminished. Observation of the crack path revealed that the fatigue crack propagate mainly to the interfaces and across the hoop direction of short fibers, however crack seldom propagate though the particle for their low aspect ratio. Overall experimental results was shown that Particle reinforcing was enhanced the fracture toughness and fatigue threshold and induced the resistance of crack propagation.

Glass/Al/Al₂O₃/a-Si 구조의 알루미늄유도 결정화에서 산화막 두께 변화가 실리콘 결정립에 미치는 영향

오광환(Oh Kwang Hwan),정혜정(Jeong Hyejeong),지은옥(Chi Eun-Ok),김지찬(Kim Ji Chan),부성재(Boo Seongjae) 한국태양에너지학회 2010 한국태양에너지학회 학술대회논문집 Vol.2010 No.4

Characteristics of crystallization of amorphous silicon (a-Si) utilizing aluminum-induced crystallization (AIC) and layer exchange process with a glass/Al/Ox/a-Si structure are investigated in this paper. The fabrication of polycrystalline silicon (pc-Si) seed layer for a pc-Si thin film solar cell with the maximum grain size of 45 ㎛ in length is carried out by appropriately adjusting the oxide film thickness and annealing temperature. Aluminum oxide (Al₂O₃) film which plays a significant role as the buffer layer between Al and amorphous silicon (a-Si) films was sputtered on the Al/glass bilayer with the different thicknesses. The a-Si was deposited on the Al₂O₃ thin film by plasma enhance chemical vapor deposition (PECVD) method. The workpieces were heated for two hours to induce AIC process at three different temperatures of 450, 500 and 550℃. Once the a-Si was crystallized by AIC process, the silicon peak of 520 ㎝?¹ from Raman spectroscopy analysis was detected regardless of Al₂O₃ layer thickness even if the degree of crystallization can exist. The Si grains with an average size ranging from 25 to 45 ㎛ can be fabricated with the same thickness ratio of a-Si/Al. From X-ray diffraction (XRD) data, the dominant crystal orientation of Si(111) together with Si(202), Si(220), Si(311) and Si(400) is found at the relatively high temperature over 500℃ whereas no Si crystal peak except Si(202) can be obtained at 450℃ after annealing. The effects of process variables such as buffer layer thickness, annealing temperature and heating time upon the AIC results including grain size and orientation of pc-Si are demonstrated in detail.

110 ∼154㎸급 XLPE 케이블용 간편 접속재 개발

신두성(Doo Sung Shin),오동윤(Dong Yun Oh),전종석(Jong Seok Jeon),오현영(Hyun Young Oh),오광환(Kwang Hwan Oh),강채홍(Chae Hong Kang) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7

초고압 XLPE 케이블용 접속재로서 고무 일체형 접속재(Pre-molded Joint)가 국내뿐만 아니라, 전 세계적으로 널리 사용되고 있다. 이러한 고무 일체형 접속재의 설치에는 일반적으로 기계적인 힘을 이용하여 삽입하는 방식이 널리 적용되고 있으나, 삽입기와 같은 특수 장비가 사용되고 있어서 설치 시간이 많이 소요되고 설치 공간의 제약을 받게 된다는 단점이 있다. 본 논문에서는, Spiral strip pipe를 이용하여 공장 내에서 확관, 출하한 고무슬리브를 현장에서 이러한 strip을 손으로 잡아당겨 풀면서 간단하게 설치할 수 있는 Cold Shrinkable type의 간편 접속재 개발에 관하여 서술하였다. 국내 및 해외 적용을 위하여 110∼154㎸급 공용으로 개발하였으며, 개발 시험 결과 및 해외 공인 기관 인증 시험 진행을 간략하게 서술하였다.

신문(神門), 태백혈(太白穴)에 시행된 직자법(直刺法), 수기사법(手技瀉法)및 침습형 레이저 시술이 고혈압 백서에 미치는 영향

나창수 ( Chang Su Na ),윤대환 ( Dae Hwan Youn ),최찬헌 ( Chan Hun Choi ),이석희 ( Suk Hee Lee ),오광환 ( Kwang Hwan Oh ),정성호 ( Sung Ho Jeong ) 대한경락경혈학회 2008 Korean Journal of Acupuncture Vol.25 No.2

Objectives: This study was performed to investigate the effect of invasive Laser acupuncture therapy with green Light (LAT-G) at HT7(Sinmun), SP3(Taebaek) on the blood pressure in hypertensive rat induced by two kidney one clip. Methods: The experiments were performed on Sprague Dawley rats. 2K1C hypertension model was prepared by constricting the Left renal artery with a sliver clip. Animals were divided into four groups, which were simple acupuncture treatment group with straight needle insertion on the square(AT-SS), acupuncture treatment group with reducing manipulation in the opposite channel direction(AT-RD), Laser acupuncture treatment group with green Light 532 nm, 10mW power in the opposite channel direction(LAT-G10) and Laser acupuncture treatment group with green Light 532 nm, 20mW power in the opposite channel direction(LAT-G20). The treatments were performed once per two days for 10 days. Results: Body weight was increased significantly in LAT-G20 group compared with AT-RD group. The blood pressure was significantly decreased in LAT-G20 and LAT-G10 groups compared with AT-SS group. Conclusions: These results suggest that green Laser acupuncture therapy at SP3·HT7 is more effective than straight needle insertion on the square for controlling hypertension. It is possible that invasive green Laser acupuncture therapy (532 nm) can be used as a reducing method of the traditional acupuncture techniques.

레이저 빔 가공과 방전 가공을 이용한 복합 미세 가공

김산하(Sanha Kim),정도관(Do Kwan Chung),김보현(Bo Hyun Kim),오광환(Kwang Hwan Oh),정성호(Sungho Jeong),주종남(Chong Nam Chu) Korean Society for Precision Engineering 2009 한국정밀공학회지 Vol.26 No.10