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레이저 유도 선해리 형광법(LIPE)을 이용한 화염내 OH 및 $O_{2}$ 분자의 2차원 농도 분포 측정
진성호,남기중,김회산,장래각,박승환,김웅,박경석,심경훈,김경수,Jin, Seong-Ho,Nam, Gi-Jung,Kim, Hoi-San,Chang, Nae-Kak,Park, Seung-Han,Kim, Ung,Park, Kyoung-Suk,Shim, Kyoung-Hoon,Kim, Gyung-Soo 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.12
Planar images of OH and $O_{2}$ with tunable KrF excimer laser which has a) 0.5 $cm^{-1}$ / linewidth, b) 0.5 nm tuning range, c) 150 mJ pulse energy, and d) 20 ns pulse width are obtained to determine spatial distributions of OH and $O_{2}$ in premixed $C_{3}$H$_{8}$ /O$_{2}$ flame. The technique is based on planar laser induced pre-dissociative fluorescence(PLIPF) in which collisional quenching is almost avoided because of the fast pre-dissociation. Dispersed LIPF spectra of OH and $O_{2}$ are also measured in a flame in order to confirm the excitation of single vibronic state of OH and $O_{2}$, OH and $O_{2}$ are excited on the P$_{2}$(8) line of the $A^{2}$.SIGMA.$^{+}$(v'= 3)-X$^{2}$.PI.(v'||'||'&'||'||'quot;= 0) band and R(17) line of the Schumann-Runge band B$^{3}$.SIGMA.$_{u}$ $^{[-10]}$ (v'= 0)- X$^{3}$.SIGMA.$_{g}$ $^{[-10]}$ (v'||'||'&'||'||'quot;= 6), respectively. Dispersed OH and $O_{2}$ spectra show an excellent agreement with simulated spectrum and previous works done by other group respectively. It is confirmed that OH widely distributed around flame front area than $O_{2}$.
변형률 속도 효과를 고려한 355㎚ UV 레이저 다중 펄스 미세가공의 전산해석에 관한 연구
이정한(Jung Han Lee),오재용(Jae Yong Oh),박상후(Sang Hu Park),남기중(Gi-Jung Nam),류광현(Gwang-Hyun Ryu),신석훈(Suk-Hun Shin),신보성(Bo-Sung Shin) Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.10
UV laser micromachining of metallic materials has been used in microelectronic and other industries. This paper shows on experimental investigation of micromachining of copper using a 355㎚ UV laser with 50㎱ pulse duration. A finite element model with high strain rate effect is especially suggested to investigate the phenomena which are only dominated by mechanically pressure impact in disregard of thermally heat transfer. In order to consider the strain rate effect, Cowper-Symonds model was used. To analyze the dynamic deformation during a very short processing time, which is nearly about several tens nanoseconds, a commercial Finite Element Analysis (FEA) code, LS-DYNA 3D, was employed for the computational simulation of the UV laser micro machining behavior for thin copper material. From these computational results, depth of the dent (from one to six pulsed) were observed and compared with previous experimental results. This will help us to understand interaction between UV laser beam and material.
특집 : 레이저 기반 초정밀 초고속 가공시스템 - 신개념 레이저 기반 초정밀/초고속 레이저 복합/유연 가공 기술 개발
류광현,남기중,Ryu, Gwang-Hyeon,Nam, Gi-Jung 재료연구소 2010 機械와 材料 Vol.22 No.1
전자부품산업이 빠르게 발전하고 있기 때문에 고기능성 PCB의 수요 또한 많이 늘고 있다. 이러한 PCB는 전자제품의 굴곡성(flexibility) 있는 형태로 발전하여 전자제품의 소형화 및 고밀도화가 가능하고, 반복적인 굴곡에 높은 내구성을 갖는 연성(flexible) PCB(FPCB)의 사용이 증가하고 있으며, 이런 시장의 요구에 맞춰 연성 다층 구조의 FPCB에 대한 정밀 고속 가공 기술에 대한 수요도 급격히 확대되고 있다. 따라서 장비 운영의 효율성 극대화 및 설비 투자를 최소화하고 단일 장비로 절단(half cut, full cut), 제거, 트리밍, 리페어 고정 등을 수행할 수 있는 장비 개발을 위한 스캐너/스테이지 고정밀 제어, Z축 스텝가공, 멀티포인트 비전 인식을 통한 왜곡 최소화 등의 요소기술 개발관련 내용을 소개하고자 한다.
자외선 피코초 레이저를 이용한 Low-k 웨이퍼 인그레이빙 특성에 관한 연구
문성욱,배한성,홍윤석,남기중,곽노흥,Moon, Seong-Wook,Bae, Han-Seong,Hong, Yun-Suk,Nam, Gi-Jung,Kwak, No-Heung 한국반도체디스플레이기술학회 2007 반도체디스플레이기술학회지 Vol.6 No.1
Low-k wafer engraving process has been investigated by using UV pico-second laser with high repetition rate. Wavelength and repetition rate of laser used in this study are 355 nm and 80 MHz, respectively. Main parameters of low-k wafer engraving processes are laser power, work speed, assist gas flow, and protective coating to eliminate debris. Results show that engraving qualities of low-k layer by using a laser with UV pico-second pulse width and high repetition rate had better kerf edge and higher work speed, compared to one by conventional laser with nano-second pulse width and low repletion rate in the range of kHz. Assist gas and protective coating to eliminate debris gave effects on the quality of engraving edge. Total engraving width and depth are obtained less than $20\;{\mu}m$ and $10\;{\mu}m$ at more than 500 mm/sec work speed, respectively. We believe that engraving method by using UV pico-second laser with high repetition rate is useful one to give high work speed in laser material process.
서명희(Myung-hee Seo),류광현(Kwang-hyun Ryu),남기중(Gi-jung Nam) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.9
Laser welding of thermoplastics is a new jointing technique with a host of advantages. It is not only another extremely useful welding method but also a cost-effective alternative to traditional techniques involving screws or adhesives. Transmission laser-welding of thermoplastics such as polycarbonate(PC), polypropylene(PP), polyvinyl chloride(PVC), low density polyethylene(LDPE) and acrylic using a high power diode laser has been studied experimentally. The optical transmission of each plastic has been measured at laser wavelength of 808nm. The weld process has been characterized by the specific energy and weld time required for each plastic. The characteristics of laser welding between same plastics have also been analyzed.
자외선 나노초 펄스 레이저를 이용한 경연성(Rigid Flexible) 인쇄전자회로기판(Printed Circuit Board) 고속 절단에 관한 연구
배한성(Han Sung Bae),박희천(Hee Chun Park),류광현(Kwang Hyun Ryu),남기중(Gi Jung Nam) Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.2
High speed cutting processes of rigid flexible printed circuit board by making use of high power UV laser with nano-second pulse width have been proposed and investigated experimentally. Also robust laser cutting system has been designed and developed in order to obtain a good cutting quality of rigid and flexible PCB with multi-layers (2-6 layers). Power controller module developed for ourselves is adapted to control the laser output power in the range less than 1%. The systems show the good performance of cutting speed, cutting width and cutting accuracy, respectively. Especially we have confirmed that the short circuit problem due to the carbonized contamination occurred in cross section of multi-layers by thermal effect of high power laser has been improved largely by using multi-pass cutting process with low power and high speed.