• 한국자동차공학회논문집
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• 제20권5호
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• pp.53-64
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• 2012

Deep and narrow welds can be produced by laser welding at high welding speeds with a narrow heat-affected zone (HAZ) and little distortion of the workpiece. This study aims to evaluate the usefulness of laser welding at automobile component manufacture. Microstructure observation, hardness test, tensile test and fatigue life test are performed by using the fiber laser welded SPFC590 steel sheets which is used widely in the manufacture of automotive seat frame. Three kinds of specimens are only a SPFC590 steel plate, quasi-butt joint plate and lap joint plate by laser welding. The following results that will be helpful to understand the static strength, fatigue crack initiation and growth mechanism were obtained. (1) The tensile strength of quasi butt joint specimens nearly equal to base metal specimens, but lap joint specimens fractured in shear area of weld metal. (2) The fatigue strength of quasi-butt joint specimen was approximately 8 percent lower than that of the base metal specimens. Furthermore, the lap joint specimens were less than 86 percent of the base metal specimens. (3) The lap joint fatigue specimens fractured at shear area in high level stress amplitude, while fractured at normal area in low level stress amplitude. From these results, the applicability of the laser welding to the automobile component is discussed.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제26권5호
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• pp.481-489
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• 2000

This research was focused on overall examination of tissue alteration, wound healing promotion. After the hair on the dorsal surface was shaved, $5{\times}5mm$ oval skin defect was formed. Experimental wounds of right side were irradiated on every day for 90 second with Ga-Al-As semi-conductor laser. Left side wounds served as control group. The rats were sacrificed on the 1st, 3rd, 5th, 7th, 14th, 21th day. For light microscopically, parafin section were stained with H&E, MT. The outcomes were as follows : 1. On 1st day, experimental and control group were seen acute inflammatory cell infiltration, edema. 2. On the 3rd days, both groups were seen crust development, collagen, blood vessel proliferation. 3. On the 5th days, experimental group were reduced edema and inflammatory cell infiltration than control group. 4. On the 7th days, both groups were observed edema, inflammatory cell infiltration disappearance and keratinocytes motility from wound defect. 5. On the 14th days, experimental group appeared collagen, blood vessel proliferation and hair follicle than control group. 6. On the 21th days, both groups were seen normal status re-epithelization. According to the above results, The wound-healing stimulated by laser radiation involves an increased rate of epithelial growth. LLLT was confirmed that it has fibroblast, blood vessel proliferation, influence initial wound healing process.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.572-573
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• 2010

단색성, 지향성 및 고휘도의 특성을 가지는 레이저는 광의료 분야에 적용되어 다양한 치료 분야에 사용되고 있다. 그 중 특정 파장의 빛이 세포를 자극하여 활성화 시키는 효과가 밝혀지며 레이저를 이용한 치료법이 각광 받기 시작했다. 하지만 기존에 사용되는 저출력 레이저는 매우 고가이며 사용이 어려운 단점을 가지고 있다. 본 연구에서는 다양한 파장 및 출력의 발생이 가능한 반도체 레이저를 이용하여 세포 활성 및 증식이 가능하도록 레이저 다이오드 조사기를 개발하고 이를 사용하여 세포 활성에 미치는 영향을 확인하였다.

• Korean Journal of Acupuncture
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• 제28권3호
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• pp.1-12
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• 2011

Objectives : The purpose of this study is to review laser acupuncture studies to find possibility for applying high intensity laser to acupuncture and moxibustion treatment. Methods : Searching papers was performed using search engines of five electronic databases, including Pubmed, Thomson ISI, EMBASE, Sciencedirect, and EBSCO, from inception to May 2011 without language limitation. Inclusion criteria were clinical studies with human, randomized controlled trials (RCTs), case-control studies, and case reports. Selecting papers was performed with titles and abstracts in first step, scrutinize full text in second step, and then the extrated data was analyzed by two authors independently. The methodological quality for RCTs was evaluated using Jadad's scale. Results : Total 8 papers, (3 RCTs, 5 controlld studies, and 1 case reports), were finally selected. The study dealt with surgical laser, argon and $CO_2$ laser was one for each, with GaAs laser was two, and with new semiconductor laser, GaN, were four. The output range was from 110 mW to 15 W. The study diseases were alcohol addiction, knee osteoarthritis, bronchopneumonia and asthma for children, and circulation. All studies reported positive effect. The methodological quality in all RCTs was low because of below 3 points and all studies had few subject numbers. Conclusions : We suggest that high intensity laser can be applied to acupuncture and moxibustion. Further rigorous and well-designed study will be needed for various disease. The oriental medical society needs to take active measures to study and clinical application of acupuncture and moxibustion treatment with high intensity laser.

• Medical Lasers
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• 제10권4호
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• pp.207-213
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• 2021

Background and Objectives This study was undertaken to assess the stability and efficacy of laser therapy (808 nm), Liquiband (a commercial topical skin adhesive product), and a combination treatment, for application in oral ulcers. Materials and Methods The oral ulcer rat animal model was used to determine the efficacy of photobiomodulation, Liquiband, or combination therapy. Ulcers were induced by injecting 60% acetic acid in the oral mucosa. Three days after ulcer confirmation, the chemically induced ulcers were treated with either laser (808 nm), Liquiband, or a combination of both, every two days for 8 days (4 sessions). Combination therapy was performed by first treating with laser followed by application of the Liquiband. Reduction in ulcer area size was subsequently determined, and animals were sacrificed at 5 and 10 days after the last administration, for histological observation of the extracted oral ulcer tissue samples. Results In this study, treatment with either laser (808 nm) or commercial Liquiband product as well as the combined treatment significantly enhanced oral ulcer healing in the rat animal model. The effect of laser treatment is mainly attributed to collagen synthesis, whereas application of the Liquiband promotes vascularization and formation of granulation tissue. Our results indicate that further optimization of the combined therapy could synergistically and significantly enhance oral ulcer healing. Conclusion Laser or Liquiband treatment of oral ulcer in the rat animal model exert different outcomes, but both methods confirm significant effects relative to the untreated group. The combined treatment group with laser and Liquiband showed marked oral ulcer healing, but further optimization is required to get highly significant results and establish the potential synergistic effect of the combination therapy, as compared to the individual enhancing effects of healing oral ulcers.

• 한국임상수의학회지
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• 제30권5호
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• pp.346-352
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• 2013

본 연구는 다이오드레이저가 골관절염에 주는 영향을 평가하기 위해 실시되었다. 연구에는 10주령의 수컷 Sprague-Dawley 랫드 60마리를 사용하였고 전십자인대의 절단 (ACLT)으로 골관절염을 유발하였다. 대조군, sham군, ACLT군, ACLT와 레이저조사를 병행한 군 (ACLT+L), ACLT와 meloxicam 투약을 병행한 군 (ACLT+M)의 다섯 개의 실험군으로 나누어 연구를 진행하였다. 8주간의 연구 기간 동안 808-nm indium-gallium-arsenide (InGaAs) 다이오드레이저 조사 방법으로 Low-level laser therapy (LLLT)를 일주일에 두 번 랫드의 수술 한 오른쪽 다리에 조사하였다. 수술 후 2주, 4주, 8주에 방사선학적, 형태학적, 조직병리학적 평가를 실시하였다. 8주에 실시한 방사선학적 평가와 일반 혈액검사, 혈청 화학 검사에서는 군 간의 유의한 차이가 나타나지 않았다. 형택학적 방법과 조직병리학적 방법으로 수술 후 2주, 4주, 8주의 ACLT+L 군과 sham 군을 비교 했을 때 ACLT+L 군에서 유의하게 연골의 손상정도가 높은 것으로 나타났다. ACLT+M 군 또한 sham 군과 비교했을 때 연골의 손상이 심한 것으로 나타났다. LLLT는 ACLT 모델에서 골관절염을 예방하는 효과는 제한적이었으며, 오히려 연골의 손상을 가속화 시키는 것으로 평가 되었다. LLLT가 세포의 생존에는 영향을 주지 않으므로 레이져에 의한 직접적인 연골손상 발생보다는 레이저의 통증완화효과로 인해 불안정한 무릎관절을 계속해서 사용함으로써 연골의 손상이 가속화 된 것으로 생각 된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.397-398
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• 2008

This paper performed the basic study for fabricating the low level laser therapy apparatus, and one of the goals of this paper was to make this apparatus used handily. The apparatus has been fabricated using the 655nm laser diode and microprocessor unit. The apparatus used a 655 nm laser diode for laser medical therapy and was designed for a pulse width modulation type to increase stimulation effects. And then, each experiment was performed to irradiation group and non-irradiation group for cells. MTT assay method was chosen to verify the cell increase of two groups and the effect of irradiation on cell proliferation was examined by measuring 590nm transmittance of ELISA reader. As a result, the cell increase of cells was verified in irradiation group as compared to non-irradiation group.

• The Korean Journal of Pain
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• 제4권2호
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• pp.106-110
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• 1991

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.181-183
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• 2007

Experimental analysis was carried out to understand the fatigue phenomena of different thickness stainless steel overlap joining structure by Nd:YAG laser welding. The fatigue life was obtained through fatigue tests with the various levels of applied load. The fatigue life is related with the parameters such as gap condition and penetration depth through experiment. As the results, tensile and fatigue strength were proportional in heat input level and bead width was identified the major factor for joining strength. Also the fatigue life were decreased depend on gap condition, it was more affected at the low load level.

• Journal of Oral Medicine and Pain
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• 제19권1호
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• pp.17-23
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• 1994

This study was performed to investigate the biostimulation effects of low level laser therapy (LLLT) on the fungus, Candida albicans, during the short term of cell cycle. Samples were divided into 6 groups which were P7, P9, P11, P15< CW and CO. All samples were irradiated for 1 minute with 2 hours of elapsed time during about 27 hours of the cell cycle of Candida albicans, and the optical density was assessed by spectrophotometry every 2 hours. It was found that there was no difference between the control and any other groups irradiated with 2 hours of short interval.