• Design & Manufacturing
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• v.15 no.4
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• pp.65-71
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• 2021

In the early days of laser invention, it was simply used as a measuring tool, but as lasers became more common, they became an indispensable processing tool in the industry. Short-wavelength lasers are used to make patterns on wafers used in semiconductors depending on the wavelength, such as CO2 laser, YAG laser, green laser, and UV laser. At first, the hole of the PCB board mainly used for electronic parts was not thin and the hole size was large, so a mechanical drill was used. However, in order to realize product miniaturization and high integration, small hole processing lasers have become essential, and pattern exposure for small hole sizes has become essential. This paper intends to analyze the characteristics through patterns by exposing the PCB substrate through DMD and polygon scanner, which are different optical systems. Since the optical systems are different, the size of the patterns was made the same, and exposure was performed under the optimal conditions for each system. Pattern characteristics were analyzed through a 3D profiler. As a result of the analysis, there was no significant difference in line width between the two systems. However, it was confirmed that dmd had better pattern precision and polygon scanner had better productivity.

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.665-671
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• 2021

A 1.8 ㎛ thick polycrystalline diamond (PCD) thin film layer is prepared on a Si(100) substrate using hot-filament chemical vapor deposition. Thereafter, its thermal conductivity is measured using the conventional laser flash analysis (LFA) method, a LaserPIT-M2 instrument, and the newly proposed light source thermal analysis (LSTA) method. The LSTA method measures the thermal conductivity of the prepared PCD thin film layer using an ultraviolet (UV) lamp with a wavelength of 395 nm as the heat source and a thermocouple installed at a specific distance. In addition, the microstructure and quality of the prepared PCD thin films are evaluated using an optical microscope, a field emission scanning electron microscope, and a micro-Raman spectroscope. The LFA, LaserPIT-M2, and LSTA determine the thermal conductivities of the PCD thin films, which are 1.7, 1430, and 213.43 W/(m·K), respectively, indicating that the LFA method and LaserPIT-M2 are prone to errors. Considering the grain size of PCD, we conclude that the LSTA method is the most reliable one for determining the thermal conductivity of the fabricated PCD thin film layers. Therefore, the proposed LSTA method presents significant potential for the accurate and reliable measurement of the thermal conductivity of PCD thin films.

• Elastomers and Composites
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• v.52 no.1
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• pp.22-26
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• 2017

The thermal conductivity and the adhesive properties were measured, after synthesis of thermal conductive composite which was obtained as a result of mixing alumina or graphite with acrylic adhesive synthesized by UV polymerization. The adhesive properties of the composite were evaluated measuring the peel strength at 180 degrees, the retention, and the initial tack;the thermal conductivity was estimated using laser flash analysis. As the filler contents increased, a decrease in peel strength and initial tack and an increase in retention and thermal conductivity were observed. When compared to alumina, the adhesion of graphite showed a dramatic decrease, whereas the thermal conductivity was further enhanced. It was found out that the small size of graphite increased the mechanical interlocking between the polymer and the filler, and it was easier for graphite to come into contact with other graphite in the matrix.

• Journal of Adhesion and Interface
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• v.3 no.3
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• pp.22-29
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• 2002

UV curable coating system described here consists of double layers, namely under layer and top laser coatings. The former consists of organic-inorganic conductive materials and the latter consists of multifunctional acrylates. Transparent double layer coatings were prepared on the transparent substrates i.e. PMMA, PC, PET etc. by the wet and wet coating procedure. Their surface resistances and film properties were measured as a function of the top layer thickness and relative humidity. As the thickness of the top layer was less than $10{\mu}m$, the surface resistance in the range of $10^8{\sim}10^{10}{\Omega}/cm^2$ was obtained. The surface properties of the two-layer coating were remarkably improved compared with the single layer coating. The effects of migration of conducting materials on the film properties of multilayer coating were investigated by using contact angle and Fourier transform infrared/attenuated total reflection(FT-IR/ATR). It was found that the migration of dopant(dodecyl benzenesulfonic acid, DBSA) molecules were occurred from film-substrate interface to film-air interface in the organic conductive coating system but not in the inorganic one.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.52-52
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• 2010

본 연구에서 우리는 HPHT 처리 전 FT-IR spectrometer를 이용한 사전분석을 통해 type Ia brown 다이아몬드를 IaA, IaB, IaAB (A>B), IaAB (A=B), IaAB (A$1700-1800^{\circ}C$, 5 GPa에서 다이아몬드가 흑연화 되지 않는 범위 하에 HPHT처리를 시행하였다. 자외선-가시광선 분광분석기(UV-Vis Spectrometer, Shimadzu UV 3101PC)를 사용하여 350~800 nm에서의 가시광선 범위를 0.1nm의 분해능으로 투과(Transmittance) 모드로 측정하였고, 퓨리에 변환 적외선 분광분석기(FT-IR spectrometer, Jasco-4100)을 사용하여 $400{\sim}6000cm^{-1}$의 범위에서 $4cm^{-1}$ 의 분해능으로 흡수(Absorption) 모드로 측정한 후 HPHT 처리 전후를 비교 분석하였다. 또한 광루미네선스(Photoluminescence) 분석은 325 nm He-Cd laser를 광원으로 한(PL, Spectra-pro 2150i, Spectra-pro 2300i micro-spectrometer) 및 532 nm green laser를 광원으로 한(PL, SAS 2000)를 사용하여 각각 350~600 nm, 550~1100 nm의 범위에서 0.1nm step으로 측정하여 HPHT 처리전과 후를 비교 분석하였다. HPHT처리 후 모든 시료는 N3 center (415.4 nm), H4 center (496.4nm) 및 platelet와 연관된 ($1363\;cm^{-1}$)의 peak가 감소하였고, H3 center (503.2 nm)와 G-band가 증가하는 경향을 나타내었다. 또한 HPHT 처리 시 질소의 B집합보다 A집합이 더 감소하는 경향을 나타내었으며, A 또는 B집합의 파괴에서 발생된 질소 원자에 의해 질소의 interstitial center (594 nm)가 증가함을 알 수 있었다. HPHT 처리 후 모든 시료는 (N-V)- center가 생성됨을 확인 할 수 있었다. 결론적으로 본 연구를 통해 HPHT 처리를 통해 다이아몬드 내에 존재하는 질소결합관련 상태의 변화를 확인할 수 있었다.

• Reproductive and Developmental Biology
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• v.36 no.1
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• pp.1-6
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• 2012

This study evaluated a sexed sperm ability to produce embryos by flow cytometer. Hanwoo bulls sperm were separated to X and Y sperm via Hoechst 33342 stained with near UV laser or performed the pre-sorted without near UV laser beam in flow cytometry. Pre-sorted sperm had significantly higher viability ($84{\pm}1.15%$, $p$<0.05) compared to other sorted groups in frozen-thawed semen. For fresh semen, pre-sorted sperm had the higher viability ($79{\pm}3%$, $p$<0.05) than those of the X and Y sperm ($44.7{\pm}1.67$ and $41.7{\pm}1.2%$) separated by differences of DNA content. On the other hand, pre-sorted and X sperm sorted according to differences in DNA content had significantly higher viabilities ($24.3{\pm}1.2$ and $25.7{\pm}0.9%$, $p$<0.05) compared to that of the sorted Y sperm ($13.7{\pm}1.2%$) in the hypoosmotic swelling test. The proportion acrosome reaction in the sorted X sperm was higher ($55.0{\pm}1.7$ and $45.0{\pm}1.5%$) than those of the sorted Y-sperm ($32.3{\pm}0.9%$, $p$<0.05). However, the sperm morphologies of the sorted groups were not significantly differences. In conclusion, the sex-sorting procedure by flow cytometry affected some characteristics of Hanwoo sperm. Further study is needed to determine the optimal procedures to enhance male and female embryos and sorting accuracy.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.310-316
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• 1995

We designed the $1.3/1.55\mum$ WDM directional coupler and its coupling length was calculated with the variation of the two waveguide's core separation and other variables by the Fourier transformed scalar wave equation. We deposited the PSG films for optical waveguide by low pressure chemical vapor deposition and fabricated the WDM coupler using the laser lithography and $CF_4/O_2$ reactive ion etching process. A V -groove which was made to support and fix the optical fiber is fabricated on Si substrate by chemical etching. The WDM coupler and the V-groove are connected using UV curing epoxy. We found that propagation mode of each port of WDM coupler is single mode and maximum extinction ratio between two out ports is 6 dB for $1.3.\mum$, and 12 dB for $1.55\mum$. /TEX>.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.173-176
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• 2004

In this study we investigated post ELA(Excimer Laser Annealing) effect on SMC (Silicide Mediated Crystalization) poly-Si (Polycrystalline Silicon) to improve the characteristics of poly-Si. Combining SMC and XeCl ELA were used to crystallize the a-Si (amorphous Silicon) at various ELA energy density for LTPS (Low Temperature Polycrystalline Silicon). We fabricated the conventional SMC poly-Si with no SPC (Solid Phase Crystallization) phase using UV heating method[1] and irradiated excimer laser on SMC poly-Si, so called SMC-ELA poly-Si. After using post ELA we can get better surface morphology than conventional ELA poly-Si and enhance characteristics of SMC poly-Si. We also observed the threshold energy density regime in SMC-ELA poly-Si like conventional ELA poly-Si.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.695-703
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• 2020

The use of medical devices is increasing due to the development of medical technology. Among medical devices, it is often used in the human body for graft and treatment. Therefore, in medical institutions, various sterilization methods according to the type and material of medical devices are applied to prevent infection. Hydrophosphite (HA) materials are the most popular in bone grafts. We would like to present a sterilization method using Q-switch Nd:YAG laser with high output energy among non-ionizing radiation suitable for small medical devices. In this study, sterilization power was most ideally shown at UV wavelengths of 1.5 W, 266 nm, and 10 pulses. Different wavelength bands; infrared and visible light; showed passive sterilization, and ultraviolet A and C showed differences in sterilization according to the pulse. In laser sterilization were differences that found according to the wavelength bands and pulses.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.26 no.1
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• pp.43-58
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• 1998

The Kwinana Shoreline Fumigation Experiment (KSFE) took place at Fremantle, WA, Australia between January 23 and February 8, 1995. The CSIRO DAR LIDAR measured plume sections from near the Kwinana Power Station (KPS) stacks to up to about 5 km downstream. It also measured boundary layer aerosols and the structure of the boundary layer on some occasions. Both stages A and C of KPS were used as tracers at different times. The heart of the LIDAR system is a Neodymium-doped Yttrium-aluminum-garnet (Nd:YAG) laser operating at a fundamental wavelength of 1064 nm, with harmonics of 532 nm and 355 nm. For these experiments the third harmonic was used because the UV wavelength at 355 nm is eye safe beyond about 50 m. The laser fires a pulse of light 6 ns in duration (about 1.8 m long) and with an energy (at the third harmonic) of about 70 mJ. This pulse subsequently scattered and absorbed by both air molecules and particles in the atmosphere. A small fraction of the laser beam is scattered back to the LIDAR, collected by a telescope and detected by a photo-multiplier tube. The intensity of the signal as a function of time is a measure of the particle concentration as a function of distance along the line of the laser shot. The smoke plume was clearly identifiable in the scans both before and after fumigation in the thermal internal boundary layer (TIBL). Both power station plumes were detected. Over the 9 days of operation, 1,568 plumes scans (214 series) were performed. Essentially all of these will provide instantaneous plume heights and widths, and there are many periods of continuous operation over several hours when it should be possible to compile hourly average plume statistics as well. The results of four days LIDAR observations of the dispersion of smoke plume in the TIBL at a coastal site are presented for the case of stages A and C.