• Transactions of Materials Processing
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• v.18 no.7
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• pp.519-530
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• 2009

The study is concerned with shape correction of stamped product using the laser irradiation. As a fundamental study, laser irradiation process has been analyzed through the thermo-mechanical FE analysis. For the purpose of validation, laser scanning experiment has been carried out also. Since the deformation mechanism involved in the laser scanning is extremely complicated due to the highly temperature dependent material properties, the determination of laser scanning pattern is not easy for the application of real stamped parts. A simplified method for the application of springback correction has been suggested with the thermo-mechanical FE analysis.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.219-223
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• 2004

Korea Railroad Research Institute(KRRI) propelled sensing and measurement techniques development for measure of Lateral Force and Vertical Force With Italy to international cooperation research project for laser technology for measurement of wheel/rail interaction force. In this paper, we compared the laser technology for measurement of wheel/rail interaction force with the existing method. And then, we suggests interaction force measurement system procedure of hereafter.

• Korean Journal of Optics and Photonics
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• v.28 no.6
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• pp.356-360
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• 2017

Indium tin oxide (ITO) provides high electrical conductivity and transparency at visible and near-IR wavelengths. ITO is widely used as a transparent electrode for the fabrication of LCDs, OLEDs, and many kinds of optical applications. It is widely employed for electrodes in various electric and display sectors because of its transparency in the visible range and high conductivity. Therefore, one issue is removing a specific area of a layer of material such as ITO or metallic film on a substrate, without affecting the properties of the substrate. ITO-on-glass removal using a laser is friendlier to the environment than traditional methods. In this study, ablation of ITO film on glass using a femtosecond-laser micromachining system (wavelength 1026 nm, pulse duration 150 fs) and a nanosecond-laser micromachining system (wavelength 1027 nm, pulse duration 5 ns) are described, compared, and analyzed.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.2
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• pp.65-71
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• 2022

In the case of Mobile PKG Trend is in a situation where a decrease in Mold Top Margin is inevitable due to its miniaturization and high capacity product requirements. However, conventional laser marking technology has an average depth of deep, and when applied to narrow top margin products, PKG strength is expected to decrease due to overlapping processing, and reliability is reduced due to poor quality such as chip damage due to laser exposure. Therefore, we have secured the technology through research on low-depth laser marking solutions that can accommodate narrow top margin products. As a result of the evaluation of applicable technology application for PKG development products, it was verified that the marking depth decreased by 67% reduced and the PKG strength increased by 12%. Furthermore, the quality verification of Laser Damage that can occur through PKG Mechanical analysis was performed, and no Chip Damage defects were found. This ensured the stability of mass production application quality.

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.556-556
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• 2001

The application of the laser to the tooth hard tissue started from the removal of carious dentin with the laser performed by Goldman in 1964. With the development of the laser technology, the laser treatment with less descomfort such as pain, vibration, and noise, etc. has been attempted. Since it is difficult to give a suitable form for inlay restoration to a cavity prepared with laser, it has to be restored with adhesive resinous materials. However, various evaluation of adhesive properties of the resinous materials to lased tooth surface on the various conditions such as adgerent, irradiation condition, procedure of bond test, and adhesive materials used, etc. have been reported.(omitted)

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.626-631
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• 2002

This paper describes the weldability and mechanical behavior of JIS S45C medium carbon steel (corresponding to KS SM45C and SAE 1045) for machine structures in CW Nd:YAG laser welding. ill general, medium carbon steels have a limited application to the industrial fields in spite of good mechanical characteristics. This is due to welding difficulty because of the high carbon contents and impurities in this material. Therefore, in this study the laser weldability of medium carbon steel with adjusted contents of S and P has been investigated in order to extend the application to medium carbon steels. Several experiments and numerical simulations have been conducted to determine the characteristics of mechanical behavior in CW Nd:YAG laser welds. The results of the simulations concur with the experiment results. From the result of this study, the application possibility of CW Nd:YAG laser welding to medium carbon steel has been confirmed. Also, the appropriateness of mechanical behavior simulation has been verified to analyze and predict the welding phenomena.

• International Journal of Korean Welding Society
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• v.2 no.1
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• pp.15-20
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• 2002

This paper describes the weldability and mechanical behavior of JIS S45C medium carbon steel (corresponding to KS SM45C and SAE 1045) for machine structures in CW Nd:YAG laser welding. In general, medium carbon steels have a limited application to the industrial fields in spite of good mechanical characteristics. This is due to welding difficulty because of the high carbon contents and impurities in this material. Therefore, in this study the laser weldability of medium carbon steel with adjusted contents of S and P has been investigated in order to extend the application to medium carbon steels. Several experiments and numerical simulations have been conducted to determine the characteristics of mechanical behavior in CW Nd:YAC laser welds. The results of the simulations concur with the experiment results. From the result of this study, the application possibility of CW Nd:YAG laser welding to medium carbon steel has been confirmed. Also, the appropriateness of mechanical behavior simulation has been verified to analyze and predict the welding phenomena.

• Korean Journal of Materials Research
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• v.31 no.11
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• pp.601-607
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• 2021

Laser cladding a surface treatment process that grants superior characteristics such as toughness, hardness, and corrosion resistance to the surface, and rebuilds cracked molds; as such, it can be a strong tool to prolong service life of mold steel. Furthermore, compared with the other similar coating processes - thermal spray, etc., laser cladding provides superior bonding strength and precision coating on a local area. In this study, surface characteristics are studied after laser cladding of low carbon steel using 18%Cr-2.5%Ni-Fe powder (Rockit404), known for its high hardness and excellent corrosion resistance. A diode laser with wavelength of 900-1070 nm is adopted as laser source under argon atmosphere; electrical power for the laser cladding process is 5, 6, and 10 kW. Fundamental surface characteristics such as crossectional microstructure and hardness profile are observed and measured, and special evaluation, such as a soldering test with molten ALDC12 alloy, is conducted to investigate the corrosion resistance characteristics. As a result of the die-soldering test by immersion of low carbon alloy steel in ALDC12 molten metal, the clad layer's soldering thickness decreases.

• Journal of Welding and Joining
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• v.33 no.4
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• pp.1-6
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• 2015

Advances in laser technology have yielded a multitude of innovative processes and applications in various industries. Laser peening is a typical example invented in the mid-1990s as a surface technology, which converted residual stress from tension to compression by just irradiating successive laser pulses to metallic materials under aqueous environment without any surface preparation. The effects of laser peening have been experimentally studied on residual stress, stress corrosion cracking(SCC) susceptibility and fatigue properties with water-penetrable frequency-doubled Nd:YAG laser. In addition, laser peening has been widely used in aviation and aerospace industries, automobile manufacturing and nuclear plant. One of the most important causes to improve the above-mentioned properties is the deeper compressive residual stress induced by laser peening. Taking advantage of the process without reacting force against laser irradiation, a remote operating system was developed to apply laser peening to nuclear power reactors as a preventive maintenance measure against SCC.

• Proceedings of the KWS Conference
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• 1996.10a
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• pp.133-135
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• 1996