YAG phosphor powders were fabricated by the atmospheric plasma spraying method with the spray-dried spherical YAG precursor. The YAG precursor slurry for the spray drying process was prepared by the PVA solution chemical processing utilizing a domestic easy-sintered aluminum oxide (Al2O3) powder as a seed. The homogenous and viscous slurry resulted in dense granules, not hollow or porous particles. The synthesized phosphor powders demonstrated a stable YAG phase, and excellent fluorescence properties of approximately 115% compared with commercial YAG:Ce3+ powder. The microstructure of the phosphor powder had a perfect spherical shape and an average particle s ize of a pprox imately 30 μm. As a r esult of t he PKG t est of t he YAG p hosphor p owder, t he s ynthesized phosphor powders exhibited an outstanding luminous intensity, and a peak wavelength was observed at 531 nm.

This study is aimed at preparing and evaluating the plasma resistance of YAS (Y2O3-Al2O3-SiO2) coating layer with crystalline YAG phase contents. For this purpose, YAS frits with controlled phase contents are prepared and melt-coated on sintered Al2O3 ceramics. Then, the results of phase analysis of crystalline YAS coating layer are compared to that of YAS frits, and discussed with regard to the plasma resistance of the YAS coating layer. The phase contents of the YAS frit change in a manner different from that of the prepared YAS coating layer, presumably owing to the composition change of YAS frit during the melt-coating process. The plasma resistance of the YAS coating layer is shown to increase with the YAG phase contents in the coating layer. Comparing the weight loss of YAS coating layer with those of commercial Y2O3, Al2O3, and quartz ceramics, the plasma resistance of the prepared YAS coating layer is 8 times higher than that of quartz and 3 times higher than that of Al2O3; this layer shows 70 % of the resistance of Y2O3.

YAG (Yttrium Aluminum Garnet, Y3Al5O12) has excellent plasma resistance and recently has been used as an alternative to Y2O3 as a chamber coating material in the semiconductor process. However, due to the presence of an impurity phase and difficulties in synthesis and densification, many studies on YAG are being conducted. In this study, YAG powder is synthesized by an organic-inorganic complex solution synthesis method using PVA polymer. The PVA solution is added to the sol in which the metal nitrate salts are dissolved, and the precursor is calcined into a porous and soft YAG powder. By controlling the molecular weight and the amount of PVA polymer, the effect on the particle size and particle shape of the synthesized YAG powder is evaluated. The sintering behavior of the YAG powder compact according to PVA type and grinding time is studied through an examination of its microstructure. Single phase YAG is synthesized at relatively low temperature of 1,000 ℃ and can be pulverized to sub-micron size by ball milling. In addition, sintered YAG with a relative density of about 98 % is obtained by sintering at 1,650 ℃.

We pathologically investigated the effects of water irrigation during Er:YAG laser irradiation on wound healing in mouse skin. Fifty-one 6-week-old ICR male mice were used in the present study. Dermal wounds were generated on the skin of the backs using the Er:YAG laser at 100 mJ/pulse and 10 Hz with (4 ml/min) or without (control) water irrigation. Mice were then sacrificed on 0, 1, and 3 days after laser irradiation, and the crust of the skin and thickness of the thermal coagulation layer were evaluated pathologically. The epidermis extended faster in the water irrigation group than in the control group on 1 day. The epidermis with keratinized layers became thicker and the crust had completely detached after 3 days in the water irrigation group. The thermal coagulation layer was thinner in the water irrigation group than in the control group. Apoptotic cell death was prominent in the control group. Detachment of the crust was observed after 3 days in 50% of the water irrigation group and 20% of the control group. These results demonstrated that Er:YAG laser irradiation with water irrigation promoted faster wound healing

phosphor powders were synthesized using a seed (average particle size: 5 ) by the polymer solution route. PVA solution was added to the sol precursors consisting of the seed powder and metal nitrate salts for homogeneous mixing in atomic scale. All dried precursor gels were calcined at and then heated at in atmosphere. The final powders were characterized by using XRD, SEM, PSA, PL and PKG test. All synthesized powders were crystallized to YAG phase without intermediate phases of YAM or YAP. The phosphor properties and morphologies of the synthesized powders were strongly dependent on the PVA content. Finally, the synthesized phosphor powder heated at , which is prepared from 12:1 PVA content and has an average particle size of 15 , showed similar phosphor properties to a commercial phosphor powder.

YAG:Ce yellow phosphor particles were synthesized by spray pyrolysis with changing the solution properties and their luminous properties, crystal structure, and morphological changes were studied by using PL measurement, XRD, and SEM analysis. It was clear that the solution properties significantly affected the crystal phase, crystallite size, the PL intensity, and the morphology of YAG:Ce particles. At low calcination temperature, the addition of urea only to the spray solution was helpful to form a pure YAG phase without any impurity phases, as the result, the highest luminescence intensity was achieved at the calcination temperature of . When the calcination temperatures were larger than , however, the YAG particles prepared without any additive showed the highest luminescent intensity. Regardless of the solution conditions, the emission intensity of YAG:Ce particles prepared by spray pyrolysis showed a linear relation with the crystallite size. In terms of the morphology of YAG:Ce particles, the addition of both DCCA and to the spray solution was effective to prepare a spherical and dense structured YAG particles.

레이저 용발법에 의한 금속 표면 제염특성을 평가하였다. 레이저로는 파장 532 nm, 펄스에너지 150 mJ, 펄스폭 5 ns의 큐스위치 Nd:YAG 를 적용하였고, 금속 표면에 CsNO3, Co(NH4)2(SO4)2, Eu2O3 그리고 CeO2를 오염시켜 이들의 제염 특성을 평가하였다. 제염 변수로는 레이저 적용횟수, 레이저 에너지 밀도 및 레이저 조사 각도 특성을 평가하였으며 각각 8, 13.3 J/cm2 및 30o의 최적 조건을 확인하였다. 제염 효율은 오염성분의 비점과 관련이 있었으며 CsNO3>Co(NH4)2(SO4)2>Eu2O3>CeO2 순이었다. 또한 여러 에너지 밀도 조건에서 스테인레스 스틸 재질의 식각 깊이 제어 특성을 규명하였다.

A 532 nm Nd-YAG laser was applied to crystallize amorphous Si thin films in order to evaluate the applicability of a Nd-YAG laser to low-temperature polycrystalline Si technology. The irradiation of a green laser was controlled during the crystallization of amorphous Si thin films deposited onto glass substrates in a sophisticated process. Raman spectroscopy and UV-Visible spectrophotometry were employed to quantify the degree of crystallization in the Si thin films in terms of its optical transmission and vibrational characteristics. The effectiveness of the Nd-YAG laser is suggested as a feasible alternative that is capable of crystallizing the amorphous Si thin films.

Yttrium aluminum garnet (YAG) powders were synthesized via mechanochemical solid reaction using with three types of aluminum compounds. reacted mechanochemically with all A1 compounds and formed YAM (yttrium aluminum monoclinic), YAG and YAP (yttrium aluminum perovskite) phases depending on the starting materials. The ground samples containing showed the best reactivity, whereas the ground sample containing A100H, which had the largest surface area, exhibited pure YAG after calcination at . The sample containing Al had the least reactivity, producing YAP along with YAG at . The types and grinding characteristics of the starting materials and grinding time are believed to be important factors in the mechanochemical synthesis of YAG.

Pure and stable YAG powders were synthesized by a PVA (polyvinyl alcohol) polymer solution technique. PVA was used as an organic carrier for the precursor ceramic gel. The precursor gels were crystallized to YAG at relatively a low temperature of . The synthesized powders, which have nano-sized primary particles, were soft and porous, and the porous powders were ground to sub-micron size by a simple ball milling process. The ball-milled powders were densified to 94% relative density at for 1h. In this study, the characteristics of the synthesized YAG powders were examined.

본 연구에서는 실리콘 wafer위에 sputtering방법으로 진공증착된 CoNbZr 비정질 박막을 Nd:YAG 레이저로 식각하기 위한 실험을 했는데, 금속의 경우 표면에서 빛의 반사율이 매우 크기 때문에 파장이 1.06μm인 Nd:YAG 레이저의 에너지를 흡수하는 것이 매우 어려우므로 식각이 거의 이루어지지 않았다. 그래서 이러한 문제를 해결하기 위한 새로운 시도로서 본 연구에서는 빛의 흡수율이 좋은 검은색의 polymer막을 금속박막의 표면에 도포하고 이 polymer막 위에 레이저를 조사해서 금속박막의 식각하는 실험을 실시하였다. 기존의 방법으로는 laser power가 332W나 되는데도 식각이 거의 일어나지 않았지만 본 연구의 방법을 이용했을 때는 laser power가 114W로 1/3정도 밖에 안 되는데도 레이저 식각이 비교적 양호하게 이루어졌다. 이는 검은색의 polymer층이 Nd:YAG 레이저 에너지의 흡수 및 전달 층의 역할을 하기 때문인 것으로 생각된다.

The aim of this study is to assess a looseness in a bolt being utilized for connecting components of a structural elements with the help of an Nd:YAG pulsed laser scanning system. Ultrasonic wave propagation imaging (UWPI) of a waveform generated using laser light and recorded by AE sensor was first found. Filtering operation was performed to remove an incident wave. The energy in the reflected wave was further assessed to arrive at a result which indicates structural defect has appeared, i.e., bolt loosening.