• International Journal of Contents
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• v.5 no.2
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• pp.16-19
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• 2009

In this paper, we concern about the distribution characteristics of surface temperature by the increment of time, diffusivity and heat flux on irradiating of a laser. The penetration depth corresponding to the induced constant heat flux or irradiated laser, is simulated by a computer algorithm. The distribution of temperature versus penetration depth for the variation of time and diffusivity is characterized at the constant heat flux and on irradiating of a laser. The temperature of constant heat flux at the fixed diffusivity or time, is decreased by the pattern of exponential function as the time t or diffusivity a is increased (a=10, 100, 1000). The temperature of constant heat flux is not changed but exponentially fixed with the increasing diffusivity and the fixed time. On the other hand, the temperature of laser at the fixed diffusivity or time is decreased linearly. Our results show that the characteristics of the simulated surface temperature in a semi-infinite solid are similar to the graphs on theoretical consideration.

• The Journal of Korean Physical Therapy
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• v.13 no.3
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• pp.603-611
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• 2001

This study was performed. using EGF, to observated the effect of GaAIAs laser on wound model induced designedly in lumbar region. The results of this study were as following: 1. In expression of EGF which used marker of wound healing, laser irradiating group made EGF to more induce significantly than laser non-irradiating group at 3 days. 2. EGF immunoreactivity in epidermis were increased markedly 3 days after wound, and increased gradually from 1 day to 2 days in wound which is laser irradiation. Therefore, EGF immunoreactivity which increased after wound with GaAIAs laser irradiation indicate that GaAIAs laser have wound healing effect. This study also can become a part of scientific evidence on electrotherapy through measuring quantitively effects of GaAIAs laser in wound

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.1
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• pp.8-14
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• 2022

A computer simulation was performed to investigate the heat source distribution and temperature distribution of a laser having multiple characteristics. To simulate the actual size of a welding specimen, the temperature distributions at 0 s, 1 s, and 2 s were analyzed by increasing the domain size to 50 mm in length and 25 mm in width in a material of the same thickness. As indicated by the results, because of the characteristics of metals with high thermal conductivity, the temperature at the welding center line and the temperature distribution at the offset position were not significant. When the core part was cooled by irradiating with a laser, it cooled at a rate of up to 500 ℃/s. In contrast, when the laser was irradiated to the ring part, the cooling proceeded at a rate of over 1800 ℃/s. Comparing the relative numerical values rather than the absolute values, it was found that the cooling rate was approximately 3.6 times faster when the laser was irradiated through the ring than when the laser was irradiated through the core. As a result of irradiating with the same heat source (at 100 W) into the core, ring, and ring + core, it was confirmed that the highest temperature was irradiated to the ring part and the lowest temperature was irradiated to the core part.

• 전기의세계
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• v.29 no.2
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• pp.118-128
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• 1980

The properties of plasmas produced by high power glass laser were investigated with various methods of diagnostics. Electron temperature was estimated by measurement of soft X-ray, and ion temperature was estimated by measurement of the time-of-flight of ion. The measurement of incident and reflected laser light, and Schlieren and shadowgragh methods were also used. No influence of laser pulse duration on the temperature was observed in the case of durations 2, 4 and 10 nsecs. The effective heating of plasma occurred in about 2 nsec of beginning of incident laser pulse. The experimental results for fast rising laser pulse were discussed and the influence of resetime of laser pulse on the heating of plasma was described. Neutrons produced by irradiating laser beam to solid deuterium target were detected.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.511-514
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• 2000

This work aimed to develop ITO (Indium Tin Oxide) thin films ablation with a KrF Eximer laser required for the application in flat panel display, especially patterning into small geometry on a large substrate area. The threshold fluence for ablating ITO on glass substrate is about 0.1 J/cm$^2$. And its value is much smaller than using third harmonic Nd:YAG laser. Through the optical microscope measurement the surface color of the damaged ITO is changed into dark brown and irradiated spot is completely isolated form the undamaged surroundings by laser light. The XPS analysis showed that the relative surface concentration of Sn and In were essentially unchanged (In :Sn=5:1) after irradiating Eximer laser. Using aluminium mask made by second harmonic Nd:YAG laser the ITO patterning is carried out.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.748-751
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• 2000

Microlens made by laser radiation method have advantages in the easiness of their fabrication. The process is based on the projection of a chromium-on-quartz reticle on to the Polymer using a pulsed 248nm KrF excimer laser. Fabrication process is a fluence-dependent rate and density. The lens shape is defined by a rotationally symmetric sluence distribution with smooth radial variation in the image plane of the reticle. A typical lens of 50㎛ diameter was fabricated by irradiating 2000 laser pulses within 40 seconds. The experimental results show microlens fabrication by UV laser is possible and well worth studying further.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.3
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• pp.181-189
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• 2006

A 2D finite-element numerical simulation has been developed to investigate the generation of ultrasonic waves in a homogeneous isotropic elastic slab under a line-focused laser irradiation. Discussing the physical processes involved in the thermoelastic phenomena, we describe a model for the pulsed laser generation of ultrasound in a metal slab. Addressing an analytic method, on the basis of an integral transform technique, for obtaining the solutions of the elastodynamic equation, we outline a finite element method for a numerical simulation of an ultrasonic wave propagation. We present the numerical results for the displacements and the stresses generated by a line-focused laser pulse on the surface of a stainless steel slab.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.156-157
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• 2021

Since concrete is contaminated or radioactive during operation of nuclear power plants, it is the most important radioactive waste generated during the dismantling of a nuclear power plant. The amount of waste is different depending on the pollution state of each facility and the applied technology is different, so there is a big difference. We aim to reduce the amount of waste and increase the value of recyclability through technology to remove radionuclides attached to the surface. For this purpose, laser scabbling, which exfoliates the surface of concrete by irradiating a laser, and a facility system for controlling dust and dust are used in parallel. The purpose of this study is to evaluate the efficiency of laser scabbling by manufacturing simulated concrete for nuclear facilities, and to review the optimal mixing design conditions for nuclear facility structures.

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.7 s.172
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• pp.27-37
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• 2005

Direct writing technology on the silicon wafer surface is used to reduce the size of the chip as the miniature trend in electronic circuit. In order to improve the productivity and efficiency, the real time quality estimation is very important in each semiconductor process. In laser marking, marking quality is determined by readability which is dependant on the contrast of surface, the line width, and the melting depth. Many researchers have tried to find theoretical and numerical estimation models fur groove geometry. However, these models are limited to be applied to the real system. In this study, the estimation system for the line width during the laser marking was proposed by process monitoring method. The light intensity emitted by plasma which is produced when irradiating the laser to the silicon wafer was measured using the optical sensor. Because the laser marking is too fast to measure with external sensor, we build up the coaxial monitoring system. Analysis for the correlation between the acquired signals and the line width according to the change of laser power was carried out. Also, we developed the models enabling the estimation of line width of the laser marking through the statistical regression models and may see that their estimating performances were excellent.