• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.106-112
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• 1994

The injection-locking of the broad-area diode laser was analysed by using the Fabry-Perot model. The far-field pattern of the output beam was able to be treated by superposing the individual beams emitted from the front facet due to the multiple reflections between the front and rear facets. and the exact near and far field patterns were obtained. The angle-steering effect according to change of the incident frequency was changed was calculated and found to be 0.022 degree/GHz with a bandwidth of 120 GHz.20 GHz.

• Laser Solutions
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• v.9 no.1
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• pp.1-7
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• 2006

In order to increase the productivity of conventional microstereolithography (MSL), digital micromirror device($DMD^{TM}$) based MSL is proposed and the feasibility of 3D rnicrocomponents fabrication is demonstrated in two ways; free surface and constrained surface techniques. The clearness of optical images at the exposure plane was confirmed for the fabrication of an accurate 3D structure by controlling the dynamic viscosity of FA1260T and the shape accuracy of a structure fabricated with epoxy-based resin ($Somos^{\circledR}$ 10120) was analyzed to determine the optimum curing conditions. After finding the appropriate process variables, the feasibility of multiple microstructures is then demonstrated. Due to the high productivity, MSL using $DMD^{TM}$ showed the potential to replace the existing focused laser beam MSL.

• Journal of the Optical Society of Korea
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• v.10 no.2
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• pp.86-90
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• 2006

The external feedback effect on the relative intensity noise (RIN) characteristics of blue InAlGaN laser diode has been analyzed taking into account the spontaneous emission noise and the injection current for the high frequency modulation. A Langevin diffusion model was exploited to characterize its relative intensity noise. The simulation parameters were quantitatively evaluated from the optical gain properties of the InAlGaN multiple quantum well active regions by using the multiband Hamiltonian for the strained wurtzite crystals. The extracted parameters were then applied to the rate equations taking into account the external feedback and the high frequency modulation current. The RIN characteristics were investigated to optimize the low frequency laser diode noise characteristics.

• Journal of the Optical Society of Korea
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• v.13 no.3
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• pp.386-391
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• 2009

PSPICE circuit parameters of the blue laser diodes grown on wurtzite AlGaInN multiple quantum well structures were extracted directly from the three level rate equations. The relevant optical gain parameters were separately calculated from the self-consistent multiband Hamiltonian. The resulting equivalent circuit model for a blue laser diode was schematically presented, and its modulation characteristics, including the pulse response and the frequency response, have been demonstrated by using a conventional PSPICE.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.35 no.9
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• pp.375-379
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• 1986

The HCP(Hypocycloidal Pinch) device for plasma focus was modified for a pumping source of the dye laser, and the spectral distribution and time behavior of its light pulses were investigated by using a UV spectrometer, 70 MHz CRO and Si-PIN photodiode detector. An array of multiple stages of HCP and narrower electrode gaps were chosen in order to make a more uniform discharge along the HCP axis. The possible spectral range for the pumping of dye laser is 360-620nm, when the HCP is operated at 5-8kv of apllied voltage and 50-150Torr of Ar fill gas pressure. The rise-time and FWHM of light pulses from the HCP are 5us and 30-50us respectively when it is operated under the same conditions as above.

• Journal of Preventive Medicine and Public Health
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• v.30 no.2 s.57
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• pp.402-412
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• 1997

The purpose of this study is to examine the factors influencing the allergic rhinitis patients' satisfaction with laser surgery. The data were collected by telephone interviews with 211 patients who visited I university hospital. The statistical methods used for the analysis were factor analysis, reliability test, and hierarchical multiple regression. We find that satisfaction level is a function of not only the surgery outcome but also the socio-psychological experience during treatment. With the improvement in nasal allergic condition, patients were more likely to be satisfied with medical services. And patients who had positive experience with physicians and facilities reported higher satisfaction level. While the surgery outcome explained 68% of the variation of satisfaction level, socio-psychological experience explained 23% of it. This result clearly shows that physicians need to pay attention to the socio-psychological aspect as well as the technical aspect of medical services.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.396-401
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• 1999

In this study, $Ar^+$ ion laser etching process of single/poly-crystalline Si with $CCl_2F_2$ gas is investigated for MEMS applications. In general, laser direct etching process is useful in microelectronic process, fabrication of micro sensors and actuators, rapid prototyping, and complementary processing because of the advantages of 3D micromachining, local etching/deposition process, and maskless process with high resolution. In this study, a pyrolytic method, in which $CCl_2F_2$ gasetches molten Si by the focused laser, was used. In order to analyze the temperature profile of Si by the focused laser, the 3D heat conduction equation was analytically solved. In order to investigate the process parameters dependence of etching characteristics, laser power, $CCl_2F_2$ gas pressure, and scanning speed were varied and the experimental results were observed by SEM. The aspect ratio was measured in multiple scanning and the simple 3D structure was fabricated. In addition, the etching characteristics of $6\mum$ thick poly-crystalline Si on the insulator was investigated to obtain flat bottom and vertical side wall for MEMS applications.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.266-271
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• 1996

In this study the evaluation of RWG MQW-LD fabricated with our vertical LPE system has been carried out with measuring its optical characteristics. This laser diode operated in lateral single mode as designed, and it showed 77% of internal quantum efficiency, 18cm of internal loss and 5.5$\AA$/$^{\circ}C$ of the thermal characterictic of the lasing wavelength. From these results we conclude that the vertical LPE system are fairly good and it might he useful to fabricate MQW wafer for laser diode.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.62-67
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• 2012

Recently UV laser is widely used to process micro parts using various materials such as polymers, metals and ceramics because it has a very high intensity at the focused spot area. It is generally known that there are still some difficulties for alumina($Al_2O_3$) ceramics to directly make micro patterns like holes and lines on the surface of working material using 355nm UV laser because the alumina has a very low absorption coefficient at that wavelength. But nowadays new alumna with nano-porous holes is developed and applied to advanced micro functional parts of IT, BT and BT industries. In this paper, we are going to show the mechanism of photo-thermal ablation for nano-porous ceramics. Inside hole there is a lot of multiple reflections along the depth of hole. Experimentally we can find the micro hole drilling and micro grooving on the surface of nano-porous alumina.

• Journal of Internet Computing and Services
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• v.18 no.6
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• pp.15-23
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• 2017

Wireless power transmission (WPT) for wireless charging is currently attracting much attention as a promising approach to miniaturize batteries and increase the maximum total range of an electric vehicle. The main advantage of the laser power beam (LPB) approach is its high power transmission efficiency (PTE) over long distance. In this paper, we present the design of a laser power beam based WPT system, which has a best WPT channel selection technique at the receiver end when multiple power transmitters and single power receiver are operated simultaneously. The transmitters send their transmission channel information via optically modulated laser pulses. The receiver uses the received signal strength indicator and digitized data to choose an optimum power transmission path. We modeled a vertical multi-junction photovoltaic cell array, and conducted an experiment and simulation to test the feasibility of this system. From the experimental result, the standard deviation between the mathematical model and the measured values of normalized energy distribution is 0.0052. The error between the mathematical model and measured values are acceptable, thus the validity of the model is verified.