• International Journal of Korean Welding Society
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• 제3권1호
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• pp.2-7
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• 2003

Laser welding application for car body manufacturing has many advantages in the stiffness and the lightness of vehicle, the productivity of assembly line, and the degree of freedom in design. This presentation will express the innovation of car body manufacturing including parameter optimization, process modeling, and system integration. In this application the investment for systems was cut down dramatically by real time switching over the laser path between two welding stations. Points of technical discussion are as follows; optimization of parameters such as laser power, robot speed and trajectory, compact and useful design of jig & fixture to assure welding quality for 3 sheet-layer zinc-coated steel, system integration between 4㎾ Nd:YAG laser device and the other systems, on-line real time welding quality monitoring system, perfect safety standards for high power laser, minimization of consumption costs such as arc lamp, protective glass for optic, etc. This application was successfully launched mass production line in 2001. The laser-welded line of side panel consists of 122 stitches totally. And the length is about 2.4m.

• 한국전기전자재료학회논문지
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• 제21권7호
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• pp.674-678
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• 2008

Low level laser therapy has various therapy effects. This paper performed the basic study for fabricating the low level laser therapy apparatus, and one of the goals of this paper was to make this apparatus used handily. The apparatus has been fabricated using the laser diode and microprocessor unit. The apparatus used a 635 nm laser diode for laser medical therapy and was designed for a pulse width modulation type to increase stimulation effects. In this study, the designed device was used to find out how 635 nm laser diode affected the skin injury of SD-Rat(Sprague-Dawley Rat). We divided the participants into two groups; irradiation group which was irradiated 10 minutes a day for 9 consecutive days, and none irradiation group. The results showed that the study group had lower incidence of inflammation and faster recovery, compared with the control group.

• 한국초전도ㆍ저온공학회논문지
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• 제25권2호
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• pp.14-18
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• 2023

Superconducting layers deposited on the metal substrate using the pulsed laser deposition process (PLD) play a crucial role in exploring new applications of superconducting wires and enhancing the performance of superconducting devices. In order to improve the superconducting property and increase the throughput of superconducting wire fabricated by pulsed laser deposition, high temperature heating device is needed that provides high temperature stability and strong durability in high oxygen partial pressure environments while minimizing performance degradation caused by surface contamination. In this study, new heating device have been developed for PLD process that deposit and growth the superconducting material continuously on substrate using reel-to-reel transportation apparatus. New heating device is designed and fabricated using iron-chromium-aluminum wire and alumina tube as a heating element and sheath materials, respectively. Heating temperature of the heater was reached over 850 ℃ under 700 mTorr of oxygen partial pressure and is kept for 5 hours. The experimental results confirm the effectiveness of the developed heating device system in maintaining a stable and consistent temperature in PLD. These research findings make significant contributions to the exploration of new applications for superconducting materials and the enhancement of superconducting device performance.

• 한국산업융합학회 논문집
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• 제20권4호
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• pp.307-311
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• 2017

Ultra short pulse laser processing with the PI (polyimide) substrate is conducted to increase flexibility and radius of curvatures. A femtosecond laser is used to perform micro machining by minimizing the heat effect in PI substrate. The laser processing according to the parameters, such as fabricated line width, depth, laser power, distance between lines, is carried out to understand the characteristics of fabricated lines. A bending test is carried out to evaluate bending shapes and the radius of curvature after bending and spreading it 1000 times. The results demonstrates that the radius of curvature decreases in deepen lines and increases with the augment of the number of the fabricated lines, and distance between lines.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.844-847
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• 2001

The application of laser direct etching has been discussed, and believed that the process is a very powerful method for micro machining. This study is focused on the micro patterning technology using laser direct etching process with no chemical damage of the material surface. A new introduced concept of energy synergy effect for surface micro machining is the combination of chemically ion reaction and laser thermal process. The etchant can't etch the material in room temperature, and used Ar laser has not power enough to machine. But, the machining is occurred in local area of the material by the combined energy. Using this process, the material is especially prevented from chemical damage for electric property. We have tested this new concept, and achieved a line with $1{mu}m$ width. The Ar laser with 488nm wavelength was used. The material was Si(100) wafer, and etchant is KOH solution. The application and flexibility of this process is in great hopes for MEMS structures and fabrication of the micro electric device parts.

• 한국레이저가공학회지
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• 제2권1호
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• pp.38-42
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• 1999

As very large scale integration technology has been developed, much more accurate, reliable technology is needed for outer lead bonding. Laser soldering has been researched as an alternative for fine pitch device bonding. This study is focused on how to select optimal laser soldering variables with which solder wets parent material, the microstructural results of laser soldering and the reliability test One of popular packages, QFP100 was soldered successfully with two kinds of solder. The inspection of the joint for reliability was carried out by optical microscope, SEM, EDAX and pull test, which demonstrated the superiority of laser soldering.

• 한국광학회지
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• 제17권5호
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• pp.455-460
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• 2006

광섬유 연결 반도체레이저를 여기원으로 하는 단면여기 세라믹 Nd:YAG 레이저의 출력 특성과 레이저 출력에 영향을 미치는 열 영향에 대하여 연구하였다. 반사율이 90.4 %인 출력거울을 사용하였을 경우 약 33.8 %의 최대 출력 효율을 얻었고, 기울기 효율은 39.3 %를 나타내었다. 세라믹 Nd:YAG의 열렌즈 효과에 의해 여기 파워 6 W 이상에서 출력 감소 현상이 나타났으며, 12 W 부근에서 레이저가 발진되지 않았다.

• Journal of Information Display
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• 제8권2호
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• pp.10-14
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• 2007

A blazed $GxL^{TM}$ device is described as having high optical efficiency (> 70% for RGB lasers), and high contrast ratio (> 10,000:1), and that is highly reliable when used in a large-area laser projection system. It has a robust design and precise stress control technology to maintain a uniform shape (bow and tilt) of more than 6,000 ribbons, a $0.25-{\mu}m$ CMOS compatible fabrication processing and planarization techniques to reduce fluctuation of the ribbons, and a reliable Al-Cu reflective film that provided protection against a high-power laser. No degradation in characteristics of the GxL device is observed after operating a 5,000- lumen projector for 2,000 hours and conducting 2,000 temperature cycling tests at $-20^{\circ}C$ and $+80^{\circ}C$. At the 2005 World Exposition in Aichi, Japan the world's largest laser projection screen with a size of 2005 inches (10 m ${\times}$ 50 m) and 6 million pixels (1,080 ${\times}$ 5,760) was demonstrated.

• 대한전자공학회논문지
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• 제25권1호
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• pp.94-100
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• 1988

To improve the switching time of active optical bistable devices, we propose an active optical bistable device that consists of a diode laser, a transistor, and a photodetector. By implementing the proposed device we realize the optical bistable device with a 5 nanosecond switching time. This is the fastest switching time among the hybrid type optical bistable devices. It is also experimentally demonstrated that the proposed device may be used in an optical disc pick up.

• ETRI Journal
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• 제30권3호
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• pp.480-482
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• 2008

A novel InGaAsP/InP buried-ridge waveguide laser diode structure is proposed and demonstrated for use as a single-mode laser. The lateral mode of the proposed device can be controlled by adjusting the composition and thickness of the InGaAsP layer grown over the active region. Stable single-mode operation without kinks or beam-steering is achieved successfully with lateral and transverse in the junction plane even for the device with the ridge width of 9 ${\mu}m$ up to an injection current of 500 mA.