• Title/Summary/Keyword: Ho:YAG Laser

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A HISTOLOGICAL CHANGES AND CGRP EXPRESSION AFTER EXPOSURE INJURY BY ER:YAG LASER IN DENTAL PULP OF RAT (흰쥐 치수에서 Er:YAG laser에 의한 노출손상에 따른 조직학적 변화 및 CGRP 단백질의 발현)

  • Yang, Jae-Ho;Park, Jong-Tae;Kim, Kyu-Tag;Kim, Sang-Bong;Lee, Nan-Young;Lee, Sang-Ho;Kim, Heung-Joong
    • Journal of the korean academy of Pediatric Dentistry
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    • v.35 no.1
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    • pp.11-17
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    • 2008
  • The purpose of this study was to investigate early histological changes and calcitonin gene-related peptide (CGRP) expression in the dental pulp of the rat after Er:YAG laser preparation. Occlusal cavities were prepared in the upper first molars using either Er:YAG laser and conventional bur. At 48 hours after cavity preparation, the teeth were processed for hematoxylin-eosin stain and CGRP immunohistochemistry. The results were as follows : 1. The cavity floor by Er:YAG laser preparation was more irregular shape compared with those by bur preparation and there are some cracks in the directions of dentinal tubules. 2. There were more inflammatory cell infiltration and disruption of odontoblast in the dental pulp by Er:YAG laser preparation in comparison with the dental pulp by bur preparation. 3. CGRP expression in the pulp tissue by both Er:YAG laser and bur preparations were increased and higher than in the normal pulp. The expression pattern of CGRP was more strong in the pulp by Er:YAG laser preparation. These results indicate that Er:YAG laser is useful in the operative dentistry such as caries removal and cavity preparation if properly applied.

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Metallic pattern Heat treatment by means of CW Nd:YAG Laser (CW Nd:YAG 레이저를 이용한 금형열처리)

  • Shin, Ho-Jun;Yoo, Young-Tae;Oh, Yong-Seak;Ro, Kyoung-Bo
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.1898-1904
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    • 2003
  • Laser heat treatment is an effective technique used to improve the tribological properties and also to increase the service life of automobile components such as camshafts, crankshatfs, lorry brake drums and gears. High power $CO_{2}$ lasers and Nd:YAG lasers are employed for localized hardening of materials and hence are of potential application in the automobile industries. The heat is conducted rapidly into the bulk of the specimen causing self-quenching to occur and the formation of matrensitic structure. In this investigation, the microstructrual features occurring in Nd:YAG laser hardening SM45C and $STD_{11}$ steel are discussed with the use of optical microscopic and scanning electron microscopic analysis. Moreover, This paper describes the optimisation of the processing parameters for maximum hardened depth of SM45C and $STD_{11}$ steel specimens of 10mm thickness by using CW Nd:YAG laser.

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ButWelding Characteristics of SM45C and SUS 304 using a Nd:YAG laser (SM45C와 SUS304의 Nd:YAG 레이저 맞대기용접특성)

  • Yoo, Young-Tae;Ro, Kyoung-Bo;Shin, Ho-Jun;Kim, Ji-Hwan;Oh, Young-Seok
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1302-1308
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    • 2003
  • Welding characteristics of austienite 304 stainless steel and SM45C using a continuous wave Nd:YAG laser are experimentally investigated. Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. This paper describes the weld ability of SM45C carbon steel and austienite 304 stainless steel for machine structural use by Nd:YAG laser.

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Surface Heat treatment of Die material by means of CW Nd:YAG Laser (CW Nd:YAG레이저를 이용한 금형 재료의 표면열처리)

  • Yoo Young-Tae;Shin Ho-Jun;Jang Woo-Yang
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.5
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    • pp.67-74
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    • 2004
  • Laser heat treatment is an effective technique used to improve the tribological properties and also to increase the service life of automobile components such as camshafts, crankshatfs, lorry brake drums and gears. High power $CO_2$ lasers and Nd:YAG lasers are employed for localized hardening of materials and hence are of potential application in the automobile industries. The heat is conducted rapidly into the bulk of the specimen causing self-quenching action to occur and the formation of matrensitic structure. In this investigation, the microstructrual features occurring in Nd:YAG laser hardening SM45C and $STD_11$ steel are discussed with the use of optical microscopic and scanning electron microscopic analysis. Moreover, This paper describes the optimisation of the processing parameters for maximum hardened depth of SM45C and $STD_11$ steel specimens of 10mm thickness by using CW:YAG laser.

EFFECT OF ND : YAG LASING ON TEMPERATURE RISING AND PROPERTIES OF MATTER OF DENTAL IMPLANTS (Nd : YAG LASER 조사가 치과 임플란트의 물성과 온도 상승에 미치는 영향)

  • Lee, Ho-Yong
    • The Journal of Korean Academy of Prosthodontics
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    • v.34 no.3
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    • pp.489-500
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    • 1996
  • Pulsed Nd : YAG LASER has been applied to various fields in clinical dentistry including the treatment of peri-implantitis. However, LASER can affect properties of matter of dental implants which are important to maintaining the health of peri-implant tissue and can raise its temperature during lasing. So there have been warings of using LASER to treat peri-implantitis. But, the effects of laser on dental implants itself are not certain yet. So we measured the temperature rising, examined matter of properties by SEM and EDX before and after pulsed Nd : YAG lasing various intensity. 7 TPS implants and 7 HPS implants were used and pulsed Nd : YAG LASER was used in 0.3W, 1.0W, and 2.0W. 1. 2.0W LASER made polished neck portion of HPS implants reach $39.2^{\circ}C$ after 5 seconds lasing. 2. LASER made crater-like defects on plasma sprayed surface and surfaces were melted and divided by fragments after lasing. 3. There was no specific evidence of element change after lasing.

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Study of Welding Characteristics of Inconel 600 Alloy using a Continuous Wave Nd:YAG Laser Beam (연속파형 Nd:YAG 레이저를 이용한 인코넬 600 합금의 맞대기 용접 특성 연구)

  • Song, Seong-Wook;Yoo, Young-Tae;Shin, Ho-Jun
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1154-1159
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    • 2004
  • Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. The thermal cycles associated with laser welding are generally much faster than those involved in conventional arc welding processes, leading to a rather small weld zone. Experiments are performed for Inconel 600 plates changing several process parameter such as laser power, welding speed, shielding gas flow rate, presence of surface pollution, with fixed or variable gap and misalignment between plate and plate, etc. The follow conclusions can be drawn that laser power and welding speed have a pronounced effect on size and shape of the fusion zone. Increase in welding speed resulted in an increase in weld depth/ aspect ratio and hence a decrease in the fusion zone size. The penetration depth increased with the increase in laser power . Welding characteristics of austienite Inconel 600 using a continuous wave Nd:YAG laser are experimentally investigated. This paper describes the weld ability of inconel 600 for machine structural use by Nd:YAG laser.

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Hot cracking characteristic of welding using Nd:YAG Laser beam (Nd:YAG 레이저용접에서 고온균열특성)

  • Ro, Kyoung-Bo;Yoo, Young-Tae;Oh, Yong-Seak;Shin, Ho-Jun;Kim, Ji-Hwan
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1159-1165
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    • 2003
  • The Nd:YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. In spite of its good mechanical characteristics, SM45C carbon steel has a high carbon contents and suffers a limitation in the industrial application due to the poor welding properties. The major process parameters studied in the present laser welding experiment were position of focus, travel speed and laser power.

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Welding Characteristics of SCP1 on CW Nd:Yag Laser (CW Nd:YAG 레이저에 의한 SCP1의 용접특성)

  • Shin, Byung-Heon;Yoo, Young-Tae;Shin, Ho-Jun;Yun, Chul-Jung
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.5
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    • pp.35-43
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    • 2007
  • Laser welding of metals has been widely used to improve a wear resistance and a corrosion resistance of the industrial parts. The objective of this research works is to investigate the influence of the process parameters, such as the welding for metals with CW Nd:YAG lasers. The bead-on-plate welding tests are carried out for several combinations of the experimental conditions. In order to quantitatively examine the characteristics of the butt welding, the welding quality of the cut section, stain-stress behavior and the hardness of the welded part are investigated. From the results of the investigation, it has been shown that the optimal welding condition without defects in the vicinity of the welded area and with a good welding quality is 1325W of the laser power, and 1.4m/min of laser welding speed.

Compact, Wavelength-selectable, Energy-ratio Variable Nd:YAG Laser at Mid-ultraviolet for Chemical Warfare Agent Detection

  • Kim, Jae-Ihn;Cho, Ki Ho;Lee, Jae-Hwan;Ha, Yeon-Chul
    • Current Optics and Photonics
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    • v.3 no.3
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    • pp.243-247
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    • 2019
  • We have developed a compact, wavelength-selectable, Q-switched Nd:YAG laser at mid ultraviolet for chemical warfare agent detection. The fundamental wave at 1064 nm is delivered by a pulsed solid state laser incorporating with a square-type Nd:YAG rod in a resonator closed by two crossed Porro prisms for environmental reliability. The output energy at 213 nm ($5{\omega}$) and 266 nm ($4{\omega}$) by ${\chi}^{(2)}$ process in the sequentially disposed BBO crystals are measured to be 6.8 mJ and 15.1 mJ, respectively. The output wavelength is selected for $5{\omega}$ and $4{\omega}$ by a motorized wavelength switch. The energy ratio of the $5{\omega}$ to the $4{\omega}$ is varied from 0.05 to 0.85 by controlling the phase matching temperature of the nonlinear crystal for sum-frequency generation without change of the output pulse parameters.

INHIBITORY EFFECT OF DENTAL LASERS ON THE GROWTH AND THE FUNCTION OF STREPTOCOCCUS MUTANS (각종 치과레이저의 Streptococcus mutans에 대한 증식 및 기능억제 효과)

  • Han, Kang-Seog;Kook, Joong-Ki;You, So-Young;Kim, Hwa-Sook;Park, Jong-Whi;Park, Heon-Dong;Lee, Sang-Ho
    • Journal of the korean academy of Pediatric Dentistry
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    • v.30 no.3
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    • pp.439-447
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    • 2003
  • This was performed to evaluate the inhibitory effect of laser on the growth of S. mutans. The bacterial pallets containing S. mutans KCTC 3065 were irradiated with Er:YAG laser and Nd :YAG laser by non-contact method at an intensity of 50mJ for 5 sec with the pulse repetition rates of 10Hz and 30Hz, respectively. The following results were obtained on colony count, acid producing ability, and the amount of insoluble extracellular polysaccharide synthesis. 1. The irradiation of Nd:YAG laser after photosensitization with Chinese ink inhibited the proliferation of S. mutans the most, and the irradiation of Er:YAG also inhibited the proliferation. However, the irradiation of Nd:YAG laser alone could not inhibited the proliferation of S. mutans. The pulse repetition rate did not affect significantly on the proliferation of bacteria in overall. 2. The irradiation of Nd:YAG laser after the photosensitization with Chinese ink inhibited the acid production of S. mutans the most for a certain period of time. Er:YAG laser also inhibited acid production. When Nd:YAG laser was used alone, the acid production of S. mutans was not been inhibited. The irradiation of Nd:YAG laser after photosensitization with Chinese ink inhibited the acid production ability of bacteria the most as the pulse repetition rate increased. 3. Laser irradiation did not inhibited the synthesis of insoluble extracellular polysaccharide of S. mutans. From these results, we conclude that the irradiation of Er:YAG laser and Nd:YAG laser after photosensitization with Chinese ink would inhibit the proliferation and acid production by S. mutans, which may prevent dental caries. However, this effect does not last long time so that the laser irradiation should be repeated frequently in order to obtain clinical effect; thus, this laser irradiation would not have a clinical usefulness in preventing dental caries when used solely.

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