• Laser Solutions
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• v.13 no.4
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• pp.7-13
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• 2010

Today, the most common process for generating Through Silicon Vias (TSVs) for 3D ICs is Deep Reactive Ion Etching (DRIE), which allows for high aspect ratio blind holes with low surface roughness. However, the DRIE process requires a vacuum environment and the use of expensive masks. The advantage of using lasers for TSV drilling is the higher flexibility they allow during manufacturing, because neither vacuum nor lithography or masks arc required and because lasers can be applied even to metal and to dielectric layers other than silicon. However, conventional nanosecond lasers have the disadvantage of causing heat affection around the target area. By contrast, the use of a picosecond laser enables the precise generation of TSVs with less heat affected zone. In this study, we conducted a comparison of thermalization effects around laser-drilled holes when using a picosecond laser set for a high pulse energy range and a low pulse energy range. Notably, the low pulse energy picosecond laser process reduced the experimentally recast layer, surface debris and melts around the hole better than the high pulse energy process.

• Korean Journal of Acupuncture
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• v.20 no.3
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• pp.35-47
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• 2003

Objective : The purpose of this study was to investigate the significance of the Oriental medical treatment using He-Ne laser with low energy intravascular Laser Irradiation of Blood(ILIB) through the superficial venules. Methods : The investigation of details connected with the superficial venules in the literature is performed. The investigation of details connected with the pricking blood techniques through the superficial venules in the literature is performed. The classification of the pricking blood techniques through the superficial venules by the blood-letting puncture methods in the literature is performed. The arrangement of domestic clinical treatises on the effectiveness of medical treatment using He-Ne laser with low energy ILIB through the superficial venules is performed. The consideration on the methodology for the improvement of the clinical effectiveness of He-Ne laser with low energy ILIB through superficial venules is performed. Results and Conclusions : The superficial venules are small arteries, veins and capillaries in the superficial region of the human body. In the pricking blood techniques, there are the blood-letting puncture using the implement of acupuncture to the Jing points, Extra points and superficial blood vessels and the acupuncture using the Hirudo. The methods of the blood-letting puncture are classified into the venous blood-letting puncture, the pricking , the picking out white fiber-like substances from the subcutaneous tissue, the cluster needling, the scattered needling, the blood-letting puncture of the tready collateral branch of the large channel and the blood-letting puncture of skin. The He-Ne laser with low energy ILIB through the superficial venules belongs to the Oriental medical treatment as the method of the blood-letting puncture in the vein of cubital fossa. The He-Ne laser with low energy ILIB has an effect on hyperfibrinogenemia, hyperlipidemia, speech and motor dysfunction in the case of cerebral infarction, headache, dizziness, pain and numbness. It is considered that fundamental research on the biological change of the human body, the experimental animal and the unicellular animal, and research on the effectiveness and the safety, and the development of He-Ne laser with low energy ILIB of an effective wavelength range are necessary.

• Korean Journal of Materials Research
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• v.23 no.5
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• pp.260-265
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• 2013

Silicon nanoparticle is a promising material for electronic devices, photovoltaics, and biological applications. Here, we synthesize silicon nanoparticles via $CO_2$ laser pyrolysis and study the hydrogen flow effects on the characteristics of silicon nanoparticles using high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and UV-Vis-NIR spectrophotometry. In $CO_2$ laser pyrolysis, used to synthesize the silicon nanoparticles, the wavelength of the $CO_2$ laser matches the absorption cross section of silane. Silane absorbs the $CO_2$ laser energy at a wavelength of $10.6{\mu}m$. Therefore, the laser excites silane, dissociating it to Si radical. Finally, nucleation and growth of the Si radicals generates various silicon nanoparticle. In addition, researchers can introduce hydrogen gas into silane to control the characteristics of silicon nanoparticles. Changing the hydrogen flow rate affects the nanoparticle size and crystallinity of silicon nanoparticles. Specifically, a high hydrogen flow rate produces small silicon nanoparticles and induces low crystallinity. We attribute these characteristics to the low density of the Si precursor, high hydrogen passivation probability on the surface of the silicon nanoparticles, and low reaction temperature during the synthesis.

• Laser Solutions
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• v.2 no.2
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• pp.34-41
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• 1999

A RS840 $CO_2$laser and a powder auto-feeding apparatus have been used to deposit single tracks of Ni-base superalloy on low carbon steel. In this paper, the effects of laser cladding parameters on clad geometry, dilution and microhardness are studied. As a results, the w/h ratio of the clad layer increases with decreasing powder feed rate and increasing laser scan speed. Increase of powder density and decrease of specific energy have little effect on dilution. It was found that the clad layer of the highest hardness has a structure in which fine and leaf like phases are dispersed in ${\gamma}$Ni matrix.

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.101-105
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• 2004

The laser ablation/ionization time-of-flight mass spectrometry is applied to the isotopic analysis of solid samples using a home-made instrument. The technique is convenient for solid sample analysis due to the onestep process of vaporization and ionization of the samples. The analyzed samples were lead, cadmium, molybdenum, and ytterbium. To optimize the analytical conditions of the technique, several parameters, such as laser energy, laser wavelength, size of the laser beam on the samples surface, and high voltages applied on the ion source electrodes were varied. Low energy of laser light was necessary to obtain the optimal mass resolution of spectra. The 532 nm light generated mass spectra with the higher signal-to-noise ratio compared with the 355 nm light. The best mass resolution obtained in the present study is ~1,500 for the ytterbium.

• Journal of the Korean Ceramic Society
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• v.37 no.2
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• pp.140-144
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• 2000

Laser cutting of thick diamond films is studied using a low-power(10 W) copper vapor laser. Due to the existence of the saturation depth in laser cutting, thick diamond films are not easily cut by low-power lasers. In this study, we have adopted a low thermalconductivity underlayer of alumina and a heating stage (up to 500$^{\circ}C$ in air) to prevent the laser energy from consuming-out and, in turn, enhance the cutting efficiency. Aspect ratio increases twice fromm 3.5 to 7 when the alumina underlayer used. Adopting a heating stage also increases aspect ratio and more than 10 is obtained at higher temperatures than 400$^{\circ}C$. These results show that thick diamond films can be cut, with low-power lasers, simply by modifying the thermal property of underlayer.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.151-152
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• 2008

Laser has been applied in various diagnostic and therapeutic medical fields. For last few decades, medical low-level laser devices have been introduced in market, but they have limitations which cannot convey enough energy to deep layer of tissues for diagnostic or therapeutic purposes. To address the issue, there have been many studies of using physical and chemical methods; it is one of ways to apply negative or positive pressure to tissue. However, it is hard to apply desired pressure on tissues continuously when practical laser devices arc used. In this study, we introduce a low-level laser probe which allows maintain pressure on skin tissue. Consequently, we are confident that the pressure probe for low-level laser treatment should be a useful tool in order to deliver sufficient energy for practical uses.

• The Journal of Korean Physical Therapy
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• v.9 no.1
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• pp.71-79
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• 1997

The purpose of this study were to determined the effect of laser irradiation on the fibroblast activity. Cultures of 3T3 fibroblasts were subjected to Helium Neon laser(632.8 nm) irradiation of various energy density. On one, two and three consecutive days the fibroblast monolayers wert irradiated for period from 0 to 32 minutes with 8 mW of average output power. The fibroblast activity was determined by the quantitative assay of MTT, SRB and NR after incubation of the fibroblasts for 24 hours. Results show that exposure duration from 2 min to 32 min could increase MTT at three consecutive days, whereas control and 1 min, one and two days irradiation had were not inclosed. The SRB and NR were inclosed at two and three consecutive days from 2 min to 32 min, whereas control and 1 min, and once radiation were not increased. These result demonstrate that energy density from 0.48 to 7.64 J/cm could increase cellular protein contents and fibroblast activity at more than twice irradiation of laser, whereas low energy density (less than 0.24 J/m) and once irradiation of laser had no effect. The results suggest that the beneficial effect of the He-Ne laser with adequate dose on fibroblast activity in vitro.

• Journal of Acupuncture Research
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• v.38 no.2
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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.

• Medical Lasers
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• v.10 no.2
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• pp.82-89
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• 2021

Background and Objectives Due to changes in diet and lifestyle, the number of obese people worldwide is steadily increasing. Obesity has an adverse effect on a healthy life, so it needs treatment and improvement. Research related to this is continuously being conducted. Materials and Methods The laser system to compact designed using 808 nm laser diode and Neodymium Yttrium orthovanadate generates a 1064 nm wavelength, the periodically polarized nonlinear crystal pumping laser beam. The pulsed 1064 nm wavelength beam passing through the AO Q-switch is used as the pumping light of the nonlinear optical crystal and is irradiated to the periodic polarized nonlinear optical crystal with a quasi-phase matching period. Nonlinear optical crystals use an oven to control the temperature to generate the desired 1980 nm and 2300 nm wavelengths. Results The 1980 nm and 2300 nm wavelengths generated by temperature control of nonlinear optical crystals are effective for lipolysis. A fiber catheter was used so that the laser could be directly irradiated to the fat cells. In particular, the new wavelength (1980 nm, 2300 nm) can increase the fat reduction effect with low energy (1.3 W). When a laser with a combination wavelength of 1980 nm and 2300 nm was used, an average lipolysis effect of 20% was obtained. Conclusion A mid-infrared lipolysis laser system with excellent absorption of fat and water has been developed. We conducted a princlinical study to confirm the efficacy and safety of the lipolysis laser system, and obtained good results for lipolysis with low energy.