• Journal of the Korean Society for Precision Engineering
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• v.26 no.7
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• pp.58-64
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• 2009

In this paper, an inspection mechanism based on laser scattering has been developed for the surface evaluation of infrared cut-off filters, and optimum conditions of laser scattering are determined using the design of experiment. First of all, attributes and influence factors of laser scattering are investigated and then a laser scattering inspection mechanism is newly designed based on analyses of laser scattering parameters. Also, Taguchi method, one of experimental designs, is used for the optimum condition selection of laser scattering parameters and the optimum condition is determined in order to maximize the detection capability of surface defects. Experiments show that the proposed method is useful in a consistent and effective defect detection and can be applied to surface evaluation processes in manufacturing.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1299-1306
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• 2007

The combination of laser beam and electric arc sharing common weld pool has widely been investigated since the late seventies, but it is beginning of the industrial uses. Recently, laser-GMA hybrid welding process showed possibility to overcome the tight gap tolerance with improved productivity. The laser-arc hybrid welding process is inherently complex because it has three kinds of process parameters: arc welding, laser welding and hybrid welding parameters. In this study, the optimum range of the process parameters were determined by high speed image analysis which could unveil the welding phenomena in laser-arc hybrid welding. The laser-arc hybrid welding was applied for position welding from the flat position to the overhead position and the welding characteristics were investigated.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.1
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• pp.23-29
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• 2003

Stencil is used normally as a mask for solder pasting on pad of a printed circuit board (PCB). The objective of this study is to develop a stencil cutting system and determine the optimal conditions to make good-quality stencil by using a Nd:YAG laser. The effects of process parameters such as laser power, type of mask, gas pressure, cutting speed and pulse duration on the cut edge quality were investigated. In order to analyze the cut surface characteristics (roughness, kerfwidth, dross) optical microscopy, SEM microscopy and roughness measurements were used. As a result, the optimal conditions of cutting process parameters were determined, and the practical feasibility of the proposed system was also examined by using a commercial Gerber file for PCB stencil manufacturing.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.231-234
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• 2007

A measurement technique in an industry site is basis technique which is bringing a ripple effect on an increasing productivity. Recently, a measurement request is increasing in the industry field as well as the variety field such as leisure, research. Thus, it is in point of time to secure an internal technique about measurement using a laser. In this paper, we prepare to develop the industrial precision laser distance measure device that is available measuring in several hundred meters[m]. In other words, we are planning to measure a wide distance using a laser diode that has long life and is compact, inexpensive. Through this research, we'll secure the pulse laser control technique, a signal processing, technique for distance calculation about a laser distance measurement system. And hereafter, we'll plan to commercialize a laser distance device using this research.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1085-1088
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• 2001

The process of styrofoam pattern that has been used for material of press die pattern depends chiefly on handwork. Laser manufacturing system developed to increase precision and efficiency of process that is also able to convert the design easily. Applying the RP(rapid prototyping) concept reversely, the unnecessary part of section is vapored away by heat source of laser beam after converting 3-D CAD model into cross-sectional shape information. Laser beam is line-scanned in plane specimens to measure the depth and width of cut, surface roughness, cross-sectional shape as converting laser power, scanning speed, cutting gas pressure. With these basic data, plane surface, inclined surface, hole, outer contour trimming process is experimented and optimum condition are obtained. In plane and inclined surface experiments, 15W laser power and 50mm/s scanning speed make superior processing property and 30W, 10mm/s make processing efficiency increase in trimming process. With these results, simple patterns were manufactured and the possibility of applying laser manufacturing system to styrofoam pattern was convinced.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.175-178
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• 2008

A new laser-addressing method is proposed in this paper. With the characteristic of high power and small spot size, simple structure electronic paper can be addressed only by laser source, and high quality image with 300dpi resolution can be easily achieved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1058-1061
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• 2003

In this thesis, we observed the optical characteristic of amorphous chalcogenide thin films by He-Cd laser. Also, grating formation by He-Ne laser and He-Cd laser. After analyze diffraction efficiency of the time on the $Ag(200{\AA})/As_{40}Ge_{10}Se_{15}S_{35}$ thin films. The result diffraction efficiency of Maximun 0.2% reduced according to time grating formation by He-Ne laser. Diffraction efficiency of Maximun 0.1% showed stabiliy characteristic according to time grating formation by He-Cd laser.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.6
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• pp.736-743
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• 2007

Laser welding has the advantage of high welding speed and Provides low heat distortion Thus laser welding is a very attractive process for joining thin steel sheet and surface treated steel sheet. And the major item in market for surface treated steel sheet is zinc coated steel. However. the laser welding of zinc coated steel is very difficult because of its low boiling point. Compared with zinc, on the other hand, aluminum has a high boiling point. Thus, laser weldability of aluminized steel is better than that of zinc coated steel. Moreover aluminized steel sheet is a material with excellent heat resistance, thermal reflection and corrosion resistance. The results of laser weldability of the aluminized steel for the full penetration welding will be described in this paper We focused on the investigation of the phenomenons caused by coating condition and behavior of aluminum in weld.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.4
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• pp.428-433
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• 2015

A non-symmetric laser beam was used for cutting a thin glass substrate and its effect was investigated. In laser cutting of brittle materials, controlling crack initiation on the surface is crucial; however, it is difficult to ensure that crack propagation occurs according to a designed laser path. A lot of deviation in crack propagation, especially at the edge of the substrate, is usually observed. A non-symmetric laser beam generates a non-uniform energy distribution, which enhances directional crack propagation. A 20-W pulsed YAG laser was used for cutting a thin glass substrate. Parametric analysis was carried out and the crack control of the non-symmetric laser beam was improved. A theoretical model was presented and the limitations of the proposed process were also discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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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.