• Title, Summary, Keyword: Argon laser

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Selective Laser Sintering of WC-Co Mixture (텅스텐 카바이드와 코발트 혼합물의 선택적 레이저 소결)

  • 김광희;조셉비만
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.269-274
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    • 2001
  • This paper describes the experimental results on direct selective laser sintering of WC-Co mixture. The experiments were carried out within an air, argon and nitrogen atmosphere. The main problem occurred during sintering within an air atmosphere was oxidation of WC-Co mixture. As the power of laser is increased and scanning speed is decreased, more severe oxidation takes place. Within an argon and nitrogen atmosphere the oxidation is reduced significantly. As the energy density is increased the thickness of the sintered layer is increased.

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AN IN VITRO STUDY OF THE THERAPEUTIC EFFECT OF ARGON LASER IRRADIATION ON HYPERSENSITIVE ROOTS (과민성치근에 대한 Argon laser조사의 치료효과에 관한 실험적 연구)

  • Chang, Kap-Sung;Kim, Byung-Ok;Han, Kyung-Yoon
    • Journal of Periodontal and Implant Science
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    • v.25 no.3
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    • pp.668-678
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    • 1995
  • In order to evaluate the therapeutic effect of argon laser irradiation on hypersensitive root, 60 mandibular premolars that had been extracted due to periodontal disease were treated by thorough scaling, root planing and root conditioning with tetracycline HCI(100mg/ml, 5 min.) for induction of hypersensitive root. Within middle one third of root mesial surface(30) or distal surface(30) was randomly irradiated by 0.5W-, 0.75W- and 1.0W-power for 2 minutes argon laser(HGM Inc., USA) with or without topical application of 1.23% acidulated phosphate fluoride gel(Pascal, USA). After all teeth were maintained in 2% methylene blue solution for 48 hours and cross-sectioned through irradiated surface of dried roots, methylene blue stained area was compared between irradiated side and nonirradiated side. Following results were obtained : 1. Methylene blue stained area was significantly less in the laser irradiated group than control group(p<0.05). 2. There was no significant difference in methylene blue stained area between 0.5W-power and 0.75W-power group(p>0.1) and between 0.75W-power and 1.0W-power group(p>0.1), but there was significant difference between 0.5W-power and 1.0W-power group(p<0.05). 3. There was no significant difference in methylene blue stained area between two groups with and without topical application of 0.12% acidulated phosphate fluoride gel(p>0.1). The results suggest that argon laser irradiation on hypersensitive root may reduce the hypersensitivity by obstruction of dentinal tubules.

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A COMPARATIVE STUDY ON THE ANTICARIOGENECITY OF ENAMEL SURFACE ADJACENT TO GLASS IONOMER AND RESIN RESTORATION POLYMERIZED BY VISIBLE LIGHT AND ARGON LASER (가시광선과 아르곤 레이저에 의해 중합된 글라스 아이오노머와 레진 수복물 주변 법랑질의 항우식 효과에 관한 비교 연구)

  • Yoo, Byung-Kyu;Kim, Jong-Soo;Kim, Yong-Kee
    • THE JOURNAL OF THE KOREAN ACADEMY OF PEDTATRIC DENTISTRY
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    • v.25 no.1
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    • pp.62-75
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    • 1998
  • The main purpose of this study was to compare the anticariogenecity of glass ionomer restorative material polymerized by argon laser versus visible light, The results from the present study can be summarized as follows; 1. Under the polarized light microscope, the specimens of laser-cured group showed the shallower lesion body than that of visible-light cured group, both in the stage of lesion initiation and progression. 2. Glass ionomer material cured by visible light showed shallower body of lesion than that of composite resin cured by argon laser at the stage of lesion progression(p<0.05). It was suggested fluoride released from the glass ionomer might have the additive anticariogenic effect. 3. Statistical difference between groups on depth of lesion body was evident after lesion progression (p<0.05). It was suggested that anticariogenic effect by argon laser was more effective at the stage of lesion progression than the lesion initiation. 4. The increment of lesion body during progression was highest in group IV (p<0.05). 5. Based upon the above-mentioned results of this study, it can be concluded that the advantage of anticariogenic effect and short curing time of argon laser in glass ionomer polymerization should be considered in children and adolescents whose caries activity is relatively higher.

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Etching of Silicon Wafer Using Focused Argon lon Laser Beam (집속 아르곤 이온 레이저 빔을 이용한 실리콘 기판의 식각)

  • Cheong, Jae-Hoon;Lee, Cheon;Park, Jung-Ho
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.4
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    • pp.261-268
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    • 1999
  • Laser-induced thermochemical etching has been recognized as a new powerful method for processing a variety of materials, including metals, semiconductors, ceramics, insulators and polymers. This study presents characteristics of direct etching for Si substrate using focused argon ion laser beam in aqueous KOH and $CCl_2F_2$ gas. In order to determine process conditions, we first theoretically investigated the temperature characteristics induced by a CW laser beam with a gaussian intensity distribution on a silicon surface. Major process parameters are laser beam power, beam scan speed and reaction material. We have achieved a very high etch rate up to $434.7\mum/sec$ and a high aspect ratio of about 6. Potential applications of this laser beam etching include prototyping of micro-structures of MEMS(micro electro mechanical systems), repair of devices, and isolation of opto-electric devices.

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A STUDY ON THE SHAR BOND STRENGTH OF LIGHT-CURED GLASS IONOMER CEMENTS TO DENTIN ACCORDING TO CURING TIME INDUCED BY ARGON LASER (아르곤 레이저의 조사시간에 따른 광중합형 글래스 아이오노머 시멘트의 상아질에 대한 전단결합강도에 관한 연구)

  • Cho, Young-Lin;Hwang, Ho-Keel;Cho, Young-Gon;Oh, Haeng-Jin
    • Restorative Dentistry and Endodontics
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    • v.22 no.1
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    • pp.267-277
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    • 1997
  • The purpose of this study was to evaluate the shear bond strength of light-cured glass ionomer cements to dentin surface according to curing time induced by argon laser. In this study, 160 extracted human molars with sound crown were used. The dentin surface of these teeth were exposed with high speed diamond bur under water spray and polished with 120, 320, 400, 800, 1200 grits sand paper. 160 extracted human molars were randomly assigned into four groups (control, experimental 1, 2 & 3) with 40 teeth each. Control group used a visible light curing unit, XL 1000(3M Co., U.S.A) and experimental groups used argon laser($SPECTRUM^{TM}$). And then each group subdivided into two groups (A, B) according to filling materials. Subdivided A group used Fuji II LC(GC Co., Japan), B group used Vitremer(3M Co., U.S.A). The curing units and curing time of each group were as follows : Control group : visible light, 40 seconds Experimental group 1 Experimental group 2 Experimental group 3 : argon laser, 10 seconds : argon laser, 20 seconds : argon laser, 30 seconds The glass ionomer cements were bonded to dentin surface of each specimen. The specimens were stored in 100% relative humidity at 37"c for 7days. And then, the shear bond strength were measured by universal testing machine(Shimatzu Co. Japan) at crosshead speed of 5mm/min and 100kg in full scale and analyzed statistically. The following results were obtained : 1. Experimental group 2-A showed the highest shear bond strength with $9.87{\pm}1.24$ kgf and control group B showed the lowest shear bond strength with $4.08{\pm}0.78$ kgf(P<0.01). 2. The Fuji II LC showed higher shear bond strength with $9.49{\pm}1.24$ kgf than that of the Vitremer with $4.23{\pm}1.24$ kgf. There was significant difference between Fuji II LC and Vitremer(p<0.01). 3. There was no significant differences among experimental groups according to curing time induced by argon laser. 4. There was no significant differences between control group and experimental groups according to curing units.

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MICROLEAKAGE OF COMPOSITE RESINS POLYMERIZED WITH ARGON LASER AND VISIBLE LIGHT (가시광선과 아르곤 레이저로 복합레진 중합시 미세누출에 관한 비교 연구)

  • Jang, Ki-Taeg;Chung, Tae-Ryun;Kim, Chong-Chul
    • THE JOURNAL OF THE KOREAN ACADEMY OF PEDTATRIC DENTISTRY
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    • v.23 no.4
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    • pp.899-905
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    • 1996
  • For the purpose of evaluation of microleakage of class V resin restoration, 64 extracted bovine teeth were filled with two kinds of light curing composite resins(Z-100, Clearfil) and polymerized with 40 seconds of visible light and with 10 seconds of argon laser. After 1000 thermocycling($5^{\circ}C/55^{\circ}C$), specimens were placed in 1 % methylen blue dye solution for 72 hours in $37^{\circ}C$ water bath. The specimens were sectioned at center of filling body and the degree of dye penetration was observed with a stereomicroscope. The following results were obtained, 1. Differences of the microleakage of resin restorations polymerized with 10 seconds of argon laser and 40 seconds of visible light were statistically insignificant. 2. There was more microleakage in Z-100 than clearfil and there was a statistical significancy (p<0.05).

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The Effects of the Argon Laser Irradiation on the Root Surface : A Scanning Electronic Microscopic Study (아르곤 레이저 조사시 치근면 변화에 관한 주사 전자 현미경적 연구)

  • Eun, Hee-Jong;Lim, Sung-Bin;Chung, Chin-Hyung
    • Journal of Periodontal and Implant Science
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    • v.29 no.4
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    • pp.861-872
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    • 1999
  • Since pathologic changes of exposed root surface inhibit cell attachment and new attachment of connective tissue have been made, many efforts were apply to change the exposed root surface condition. Scaling and root planing can not remove the endotoxin completely and forms the smear layer which prohibits the new attachment of connective tissue. Therefore, many kinds of chemicals were used for controlling the pathologic change of the root surface. The purposes of this study was to compare and observe the changes of the exposed root surface treated by scaling and root planning, Tetracycline HCl and Argon Laser. After the scaling and root planning of ten extracted premolars, the differences & the root surface among groups were observed under SEM. Control group showed smear layer and irregular amorphous surface. The dentinal tubule was not exposed. The debris and scale like texture were also observed. Tetracycline HCl treated group showed relatively smooth surface and the collagen fiber was observed in the dentinal tubule. Argon Laser treated group showed the most effective results under the conditions of 0.8 to 1.0w irradiation for 0.5 to 1.0 sec with pulse wave. The results of this study showed that the root surface change was associated with the intensity and the duration of Argon Laser irradiation. Further investigation for the surface change with the Argon Laser irradiation is recommended for understanding of clinical effect.

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The Effect of Argon Laser on Periodontal Disease (치주질환에 대한 Argon 레이저의 효과)

  • Ahn, Hyung-Joon;Ryu, Ji-Won;Kim, Jae-Hong;Kim, Chong-Youl
    • Journal of Oral Medicine and Pain
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    • v.30 no.2
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    • pp.277-285
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    • 2005
  • The purpose of this study was to evaluate photothermal effect of laser, which eliminates and reduces bacteria causing periodontal disease, on treatment of periodontal disease. This study included subjects with moderate periodontitis who visited the Department of Oral Medicine, College of dentistry, Yonsei University. The subjects were divided into experimental group, where Argon laser treatment was used, and control group, where conventional subgingival curettage was used. Gingival fluids from each subject were collected prior and after 1 week of the treatment, and changes in number of bacterial colonies cultured from aerobic as well as anaerobic bacteria responsible for the periodontal disease, and changes in clinical indices related to the periodontal disease, such as plaque index, gingival index, sulcus bleeding index, were analysed. As a result, the number of bacterial colonies of aerobic and anaerobic bacteria reduced after 1 week of the treatment in both groups, especially the bacterial colonies of anaerobic bacteria which showed statistically significant reduction(p<0.1). However, there was no significant difference between the experimental group and the control group. Clinical indices including plaque index, gingival index, sulcus bleeding index were reduced after 1 week of the treatment in both groups. In the experimental group, gingival index(p<0.1) and sulcus bleeding index(p<0.01) showed significant reduction, and, in the control group, sulcus bleeding index(p<0.01) showed significant reduction. However, there were no significant differences in each indices between the two groups. The above results suggest that Argon laser could be used as a substitute of conventional subgingival curettage, or in combination with subgingival curettage which would increase the effect of the treatment. Although the possibility of clinical application of Argon laser was observed in this study, more randomized-controlled research, including acquirement of sufficient samples as well as long-termed follow up, would be necessary before clinically effective application of Argon laser.

Selective Laser Sintering of WC-Co Mixture for Rapid Tooling (쾌속 금형 제작을 위한 텅스텐 카바이드와 코발트 혼합물의 선택적 레이저 소결)

  • Kim K. H.;Beaman Joseph J.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.187-194
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    • 2002
  • This paper describes the experimental results on direct selective laser sintering of WC-Co mixture for rapid tooling. The experiments were carried out within an air, argon and nitrogen atmosphere. Coupons of single layer were sintered at various laser powers, scanning speeds and scan spacings. As the energy density (energy per unit scanned area) is increased, the thickness of coupons is increased. The main problem took place during sintering within an air atmosphere was severe oxidation of WC-Co mixture. As the laser power is increased and/or scanning speed is decreased, more severe oxidation occurred. Within an argon and nitrogen atmosphere the oxidation is reduced significantly. Experiments on multi-layer sintering were also carried out.

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