• 제목/요약/키워드: Low-power laser

검색결과 370건 처리시간 0.024초

Low-k 웨이퍼 레이저 인그레이빙 특성에 관한 연구 (Study on low-k wafer engraving processes by using UV pico-second laser)

  • 남기중;문성욱;홍윤석;배한성;곽노흥
    • 한국레이저가공학회:학술대회논문집
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    • 한국레이저가공학회 2006년도 추계학술발표대회 논문집
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    • pp.128-132
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    • 2006
  • Low-k wafer engraving process has been investigated by using UV pico-second laser with high repetition rate. Wavelength and repetition rate of laser used in this study are 355nm and 80MHz, respectively. Main parameters of low-k wafer engraving processes are laser power, work speed, assist gas flow rate, and protective coating to eliminate debris. Results show that engraving qualities of low-k layer by using UV pico-second pulse width and high repetition rate had better kerf edge and higher work speed, compared to one by conventional laser with nano-second pulse width and low repetition rate in the range of kHz. Assist gas and protective coating to eliminate debris gave effects on the quality of engraving edge. Total engraving width and depth are obtained less than $20{\mu}m$ and $10{\mu}m$ at more than 500mm/sec work speed, respectively. We believe that engraving method by using UV pico-second laser with high repetition rate is useful one to give high work speed of laser material process.

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만성 요통 환자에서의 휴대용 저출력 레이저 치료기의 통증 및 기능 효과 (Efficacy of Portable Low Power Laser Therapy on Pain and Functions in Chronic Low Back Pain)

  • 조연욱;김태희;임오경;이주강;박기덕
    • Clinical Pain
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    • 제19권1호
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    • pp.1-7
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    • 2020
  • Objective: A prospective, assessor-blinded, randomized controlled trial was conducted in patients with chronic low back pain to evaluate the efficacy of portable low power laser therapy (LPLT) and the effect when combined with exercise therapy on pain and functions. Method: 60 patients were recruited and 56 patients, excluding 4 dropouts, were randomly allocated to the LPLT group (Group 1: 19 patients), placebo laser therapy with exercise group (Group 2: 18 patients), and LPLT with exercise group (Group 3: 19 patients). Laser therapy and exercise was performed five times a week for 4 weeks. Visual analogue scale (VAS), Schober test, lumbar range of motion (ROM) measures (flexion, extension and lateral flexion), Oswestry Disability index (ODI) were measured at baseline, at 4 weeks after intervention, and at 6 weeks after 2 weeks of no intervention. Results: Statistically significant improvements were noted in all group by time interaction with respect to all outcome parameters (p<0.05). All parameters in each group improved not only in the period of treatment (4 weeks), but also in the final evaluation (6 weeks) 2 weeks after the end of treatment. Post-hoc analysis showed statistically significant difference between the LPLT with exercise group and the other groups in all outcome parameters except for the ODI at 4 weeks and at 6 weeks. Conclusion: Portable LPLT is effective treatment in reducing pain and improving lumbar ROM and with exercise is more effective than laser or exercise monotherapy for the chronic low back pain patients.

자외선 피코초 레이저를 이용한 Low-k 웨이퍼 인그레이빙 특성에 관한 연구 (A Study of Low-k Wafer Engraving Processes by Using Laser with Pico-second Pulse Width)

  • 문성욱;배한성;홍윤석;남기중;곽노흥
    • 반도체디스플레이기술학회지
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    • 제6권1호
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    • pp.11-15
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    • 2007
  • Low-k wafer engraving process has been investigated by using UV pico-second laser with high repetition rate. Wavelength and repetition rate of laser used in this study are 355 nm and 80 MHz, respectively. Main parameters of low-k wafer engraving processes are laser power, work speed, assist gas flow, and protective coating to eliminate debris. Results show that engraving qualities of low-k layer by using a laser with UV pico-second pulse width and high repetition rate had better kerf edge and higher work speed, compared to one by conventional laser with nano-second pulse width and low repletion rate in the range of kHz. Assist gas and protective coating to eliminate debris gave effects on the quality of engraving edge. Total engraving width and depth are obtained less than $20\;{\mu}m$ and $10\;{\mu}m$ at more than 500 mm/sec work speed, respectively. We believe that engraving method by using UV pico-second laser with high repetition rate is useful one to give high work speed in laser material process.

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Effective Low-Level Laser Therapy Including Laser Acupuncture Treatment Conditions for Non-Specific Chronic Low Back Pain: Systematic Review and Meta-Analysis

  • Yeum, Hyewon;Hong, Yejin;Nam, Dongwoo
    • Journal of Acupuncture Research
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    • 제38권2호
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    • pp.85-95
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    • 2021
  • Low-level laser therapy including laser acupuncture has been widely used for non-specific chronic low back pain in primary Korean medical clinics. However, there is no critically appraised data regarding which treatment conditions are most effective. A systematic review and meta-analysis was conducted to determine effective treatment conditions using 12 databases (PubMed, Ovid, CENTRAL, KoreaMed, KMBASE, KISS, NDSL, KISTI, OASIS, CNKI, CiNII, and J-STAGE). There were 1,019 studies retrieved and 13 studies included in this review. It was determined that when the power output was ≥ 50 mW, the beam size was increased to ≥ cm2, the energy dose was increased to ≥ 4 J per point, the treatment interval was increased to ≥ 3 times a week, and the number of treatment sessions was increased to ≥ 10 treatments, these conditions appeared to increased treatment effectiveness.

흰쥐의 피부화상 후 저강도 레이저 조사가 Substance P의 발현에 미치는 영향 (Effects of Low Power Laser for the Expression of Substance P in the Burned Skin of the Rats)

  • 구현모;이선민;남기원;김석범;천송희;강종호;김진상
    • The Journal of Korean Physical Therapy
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    • 제15권3호
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    • pp.239-250
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    • 2003
  • This study was performed to investigate the effect of low power laser irradiation on Substance P(SP) expression in the burned skin of the rats. Burns of about 3cm in diameter were created with $75^{\cric}C$ water on the back of the rats, and the lesion of experimental group were irradiated on days 1, 2, 3 and 4 postwounding. Control leasions were not irradiated. After burns, low power laser irradiation was applied by using 1000Hz, 830nm GaAlAs(Gallium-aluminum-arsenide) semiconductor diode laser. The expression of evaluated Substance P(SP) immunohistochemistry on rabbit anti-SP The results of this study wereas follows 1. The Substance P was expressed in the lamina I and II of dorsal horn of spinal cord. In expression of SP, the lesion of control group made SP to more induce significantly than experimental leasions. 2. SP immunoreactivity in burned leasion of spinal cord were decreased markedly 4 days after burns, and decreased gradually from 1 day to 2 days in burns which is laser irradiation These data suggest that low power laser have a pain release effect in the burned skin of the rats.

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흰쥐 좌골신경 압좌손상 후 척수분절의 저강도 레이저 조사가 운동기능 회복에 미치는 영향 (Effects of Low Power Laser Irradiation on the Spinal Cord for the Functional Regeneration of Crushed Sciatic Nerve in Rats)

  • 김석범;김동현;송주민;남기원;권영실;김진상
    • The Journal of Korean Physical Therapy
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    • 제13권3호
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    • pp.569-578
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    • 2001
  • The purpose of the present study was to examine the functional recovery of the crushed sciatic nerve of rats after low-power laser irradiation applied to the corresponding segments of the spinal cord. After a crushed injury on the left sciatic nerve in rats. low-power laser irradiation was applied transcutaneously to corresponding segments of the spinal cord immediately after suture the wound by using 2000 mW, 2000Hz, 830 nm CaAIAs(Gallium-aluminum-arsenide) semiconductor diode laser. The laser treatment was performed with 10 minutes daily for 4 successive weeks. Functional recovery was evaluated per weekly following injury by sciatic function index(SFI),using data obtained by walking track analysis. For four weeks after crush injury, experimental group had significantly greater functional improvement than control group(${\alpha}$=0.05). In a experimental group, SFI was significantly increased for three weeks, but control group not increased for two weeks. This study suggests that low-power laser irradiation applied directly to the spinal cord can improve functional recovery of the crushed sciatic nerve in rats.

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흰쥐의 피부화상 후 저강도 레이저 조사가 표피성장인자의 발현에 미치는 영향 (The Effects of Low Power Laser for the Expression of Epithelial Growth Factor in the Burned Skin of the Rats)

  • 이선민;구현모;남기원;김석범;김진상
    • The Journal of Korean Physical Therapy
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    • 제14권3호
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    • pp.226-237
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    • 2002
  • This study was performed to investigate the effect of low power laser irradiation on epidermal growth factor(EGF) expression in the burned skin of the rats. Burns of about 3cm in diameter were created with 75'c water on the back of the rats, and the lesion of experimental group were irradiated on days 1, 2, and 3 postwounding. Control tensions were not irradiated. After burns, low power laser irradiation was applied by using 1000Hz, 830nm GaAlAs (Gallium-aluminum- arsenide) semiconductor diode laser. The expression of epidermal growth factor evaluated immunohistochemistry on mouse anti-EGF. The results of this study were as follows 1. In expression of EGF, the lesion of experimental group made EGF to more induce significantly than control tensions. 2. EGF immunoreactivity in burned skin were increased markedly 3 days after burns, and increased gradually from 1 day to 2 days in burns which is laser irradiation These data suggest that low power laser have wound healing effect in the burned skin of the rats.

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연속파형 Nd:YAG 레이저를 이용한 SCM4강의 표면경화에 관한 연구 (A Study on the Surface Hardening of SCM4 Steel Using a Continuous Wave Nd:YAG Laser)

  • 나기대;신병헌;신호준;유영태
    • 한국공작기계학회논문집
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    • 제16권5호
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    • pp.24-32
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    • 2007
  • Laser surface hardening is beneficially used for surface treatment of structural steel. Due to very rapid heating and cooling rates, structural low-alloy steel(SCM4) can be hardened as self quenching. The aim of this research project is to improve the influence of the process laser parameters: laser power, spot size, surface roughness, and traverse speed. The laser beam is allowed to scan on the surface of the workpiece at the constant power(1095W), varying the traverse speed at 0.3m/min, 0.5m/min and 0.8m/min. The optical lens with the elliptical profile is designed to obtain a wide surface hardening area with uniform hardness. From the results of the experiment, it has been shown that the stable hardness is about 600$\sim$700Hv, when the laser power, focal position and the traverse speed are P=1095W, z=0mm and v=0.3m/min.

연속파 Nd:YAG 레이저를 이용한 Ni-MH전지용 저탄소강의 다층 박판 용접 특성 (Multi-thin plate welding characteristics of Low Carbon Steel for Ni-MH battery of using Continuous Wave Nd:YAG laser)

  • 양윤석;황찬연;유영태
    • 한국생산제조학회지
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    • 제20권6호
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    • pp.720-728
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    • 2011
  • Lap joint welding conducts low carbon steel plates using a 2.0kW continuous wave Nd:YAG laser beam. The specimen is composed of thin plate of 20 sheets. Process Variables contain two controlled parameters of the laser power and the welding speed. In order to quantitatively examine the characteristics of the lap welding, the welding quality of the cut section, stain-stress behavior, and the hardness of the welded part are investigated. The weld width difference between the top and the bottom because the welding speed is increased. The reason, cooling rate is decreased because of fast welding speed. When the heat input is higher, larger volume of the base metal will melt and the welding heat has longer time to conduct into the bottom from the top. The microstructure and tensile properties of the joints are investigated in order to analyze the effects of heat input on the quality of laser welded specimen. From the results of the investigation, We observe that welding quality is good for the laser power of 1800W, and laser welding speed from 1.8m/min to 2.2m/min.

자동차용 무침입형 극저탄소강의 파이버 레이저 용접에 대한 연구 (A Study on the Fiber Laser welding of Ultra-Low Carbon Interstitial Free Steel for Automotive)

  • 오용석;신호준;양윤석;황찬연;유영태
    • 한국생산제조학회지
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    • 제20권3호
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    • pp.342-349
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    • 2011
  • The purpose of this paper is to describe experimental results about the butt welding and bead on plate welding of the high power Continuous Wave (CW) Fiber laser for Ultra-low carbon Interstitial Free(IF) steel plate for gear part of car. After being welded of the gear parts by the fiber laser and electron beam Microstructures of melting zone had been mixed acicular, granular bainitic, quasi-polygonal and widmanstatten ferrite because of a radical thermal diffusion after welding, difference of critical volume and grain size. As a result of experiment, when gear parts were welded by the fiber laser and electron beam, the fiber laser welding has been stable properties without internal defects more than the electron beam welding. Therefore it has the very advantages of welding high quality and productivity more than conventional melting method. The optimal welding processing parameters for gear parts were as follows : the laser power and welding speed were 3kWatt, 30mm/sec respectively. At this time heat input was $21.2{\times}10^3J/cm^2$.