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알루미나 세라믹 소재의 초단파 레이저 어블레이션량 연구
김경한,박진호,Kim, Kyunghan,Park, Jinho 한국레이저가공학회 2015 한국레이저가공학회지 Vol.18 No.4
In this paper, ablation rate of $Al_2O_3$ ceramics by femtosecond laser fluence is derived with experimental method. The automatic three axis linear stage makes laser optics to move with high spatial resolution. With 10 times objective lens, minimal pattern width of $Al_2O_3$ is measured in the focal plane. Ablated surface area is shown as linear tendency increasing number of machining times with various laser power conditions. Machining times is most sensitive condition to control $Al_2O_3$ pattern width. Also, the linear increment of pattern width with laser power change is investigated. In high machining speed, the ablation volume rate is more linear with fluence because pulse overlap is minimized in this condition. Thermal effect to surrounding medium can be minimized and clean laser process without melting zone is possible in high machining speed. Ablation volume rate decelerates as increasing machining times and multiple machining times should be considered to achieve proper ablation width and depth.
3차원 대면적 연속 마이크로 레이저 패터닝을 위한 연구
김경한,손현기,이제훈,Kim, Kyunghan,Sohn, Hyonkee,Lee, Jaehoon 한국레이저가공학회 2015 한국레이저가공학회지 Vol.18 No.4
For continuous laser micro patterning on three-dimensional free form surface, innovative laser system is developed. The two axis galvanometer is combined with the dynamic focusing unit to increase optical distance. Also, it is synchronized with the 3 axis mechanical system. To determine laser machining sequence, laser CAM system is developed. It can make possible of 3D surface micro patterning under $25{\mu}m$ pattern width. The uniformity of pattern width is about 2.8% and it is validated that focal plane is well conserved by the dynamic focusing unit. Velocity and positional information of 1 axis is stage is fed to the scanner control board by the encoder signal and it makes possible real time synchronization. With this system, possible patterning volume is enlarged from $40{\times}40mm^2$ to $40{\times}120{\times}30mm^3$.
초정밀/초고속/대면적 레이저 가공을 위한 스캐너-스테이지 연동 기술
김경한(Kyunghan Kim),이제훈(Jaehoon Lee),서정(Jung Suh) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.4
레이저 스캐너와 스테이지를 동기화 하는 연동 기술을 개발하였다. 태양전지, 디스플레이 분야, 전자부품, 자동차 부품 등의 많은 영역에서 초정밀 레이저 가공물의 면적이 넓어지고 있다. 레이저 스캐너는 초고속 가공이 가능하지만, 사용면적에 제한이 있다. 비록 스캐너 가공영역이 확대되고 있지만 여전히 스캐너 가공부위의 가장자리에서 가공의 왜곡이 발생할 수 있다. 본 연구에서 개발한 연동기술은 기존의 Step & Repeat 방식과 다르게 연속적인 스테이지 이송을 함으로써 고속가공 및 가공품질의 향상이 가능하다. We develop the on-the-fly technique to synchronize a laser scanner and a stage. Demands for high precision laser processing with wide area has been increasing for a number of applications such as in solar cell battery, display parts, electronic component, automobile industry, and so on. The ultra high speed laser scanner system is limited by its scanning size, for example 50×50㎜. Even though recently the laser scanner system was developed which can scan a wide area, the distortion of scanning quality may be serious as a scan area increasing. The developed method differentiates with an existing Step & Scanning method in that it can guarantee continuous stage movement, which may improve the processing speed and laser fabrication quality.
김경한(Kyunghan Kim),이제훈(Jaehoon Lee),윤광호(Kwangho Yoon) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
We develop the on-the-fly technique to synchronize a laser scanner and a stage. Demands for high precision laser processing with wide area has been increasing for a number of applications such as in solar cell battery, display parts, electronic component, automobile industry, and so on. The ultra high speed laser scanner system is limited by its size of scanning area, for example 50×50㎟. Even though recently the laser scanner system was developed which can scan a wide area, the distortion of scanning quality may be serious as a scan area increasing. The developed method differentiates with an existing Step & Scanning method in that it can guarantee continuous stage movement, which may improve the processing speed and laser fabrication quality.
김경한(Kyunghan Kim),박경택(KyoungTaik Park),김두형(Doohyung Kim),조규백(GyuBaeke Cho) 한국항해항만학회 2010 한국항해항만학회 학술대회논문집 Vol.2010 No.춘계
최근 고유가로 인하여 항만의 경영수지가 악화되고 있고, 발리유엔기후협약 등 기후변화에 대해 국제 환경규제에 대비한 항만분야의 대응이 필요하다. 선진국의 항만들은 안벽 하역장비 및 야드 크레인의 생산성 향상과 더불어 효율적인 터미널 운영과 하역, 보관, 이송능력 향상 및 높은 수준의 서비스를 제공하는 컨테이너터미널 하역시스템 개선 방안에 대해 지속적으로 연구 개발하고 있다. 특히 일본의 경우 재래식 컨테이너 터미널의 친환경화 및 생산성 제고를 위해 항만하역장비의 자동화 기술을 개발하였으며, 독일의 CTA에서는 야드에서의 완전 무인자동화 시스템을 운영하고 있다. 그러나 국내에서는 아직 컨테이너터미널 하역시스템 기술에 관한 연구가 부족한 실정이며, 고생산성, 저비용, 저노동력의 국제 환경변화 및 요구사항에 부합하는 항만을 개발하기 위해 고효율 친환경적인 항만하역장비 시스템 개발이 요구되고 있다. 이러한 고효율 친환경 항만 구축을 통하여 우리나라 컨테이너항만의 국제 경쟁력을 유지하고 항만기술 분야의 선도 기술을 확보하여 동북아 허브항만으로서의 위상을 제고할 수 있도록 하여야한다. Advanced countries are adopted the Eco-Green port using high energy efficiency Crane and Automated unloading system. This paper includes the case study for energy saving ECO-RTG and other automated unloading system such as, German CTA, Japan OHI, and so on.
김경한(Kyunghan Kim),서정(Jeong Suh),이제훈(Jaehoon Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Two methodologies for predicting thermal relaxation time of tissue subjected to pulsed laser irradiation are introduced by the calculation the optical penetration depth and by the investigation of the temperature diffusion behavior. First approach is that both x-axial and y-axial thermal relaxation times are predicted and they are superposed to achieve the thermal relaxation time (τ₁) for two-dimensional square tissue model. Another approach to achieve thermal relaxation time (τ₂) is measuring the time required for local temperature drop until e?¹ of the maximum laser induced heating.
Analysis of Thermal Relaxation Time of Tissues Subject to Pulsed Laser Irradiation
Kyunghan Kim(김경한),Jae-hoon Lee(이제훈),Jeong Suh(서정) 한국레이저가공학회 2009 한국레이저가공학회지 Vol.12 No.2
Two methodologies for predicting thermal relaxation time of tissue subjected to pulsed laser irradiation is introduced by the calculation the optical penetration depth and by the investigation of the temperature diffusion behavior. First approach is that both x-axial and y-axial thermal relaxation times are predicted and they are superposed to achieve the thermal relaxation time (τ1 ) for two-dimensional square tissue model. Another approach to achieve thermal relaxation time (τ 2 ) is measuring the time required for local temperature drop until e−1 of the maximum laser induced heating.