• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.3
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• pp.120-124
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• 1982

In this paper, the theoretical analysis of lateral guiding in stripe geometry DH Laser Diode is performed. In the analysis, the gain & refractive index variations in active layer are modeled by very analogous methmatical function to their real profile and the two dimensional lateral waveguiding of DH LD have been analyzed by perturbation theory. Finally, the beam width dependence of refractive index variation(n), active layer width(d), and cavity length(L), have been analyzed.

• Journal of the Korean Home Economics Association
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• v.31 no.1
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• pp.193-210
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• 1993

The purpose of this study was to investigate the effect of age, physical type and job on preference for color and fabric motifs in men's clothing design. Color preference measures consisted of clothing styles painted in CAD. Preference for fabric motifs was assesed by stripe fabrics in size, width and strength. All of the preference measures were devised specifically for this study. Furthermore, items on Hight and Weight for physical type, age and job of subjects were included I the questionnaire. Data were obtained by self-administered questionnaires form 243 men (25-54 years old) in Seoul. Analysis was by chi-square (X2), frequency, and percentage. The results obtained in this study were as follows : 1. Color preference was not affected by age and physical type, Job was related to coordinate color of men's clothing. 2. Preference for width of striped motifs was affected by age and job. 3. Preference for strength of fabric motifs in men's jacket was affected by physical type.

• Journal of the Semiconductor & Display Technology
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• v.10 no.3
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• pp.29-33
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• 2011

Film growth rate and composition variation are numerically analyzed during the selective area growth of InGaN on the GaN triangular stripe microfacet in this study. Both the vapor phase diffusion and the surface diffusion are considered to determine the In composition on the InGaN surface. To obtain the In composition on the surface, flux of In atoms due to the surface diffusion is added to the concentration determined from the Laplace equation which is governing the gas phase diffusion. The solution model is validated by comparing the growth rates from the analyses to the experimental results of GaN and InN films. The In composition and resulting wave length are increased when the surface diffusion is considered. The In content is also increased according to the increasing mask width. The effect of mask width to the In content and wave length is increasing in the case of a small open region.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.12
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• pp.84-91
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• 2004

A CCD camera with a laser stripe was applied to realize the automatic weld seam tracking in GMAW. It takes relatively long time to process image on-line control using the basic Hough transformation, but it has a tendency of robustness over the noises such as spatter and arc tight. For this reason, it was complemented with adaptive Hough transformation to have an on-line processing ability for scanning specific weld points. The adaptive Hough transformation was used to extract laser stripes and to obtain specific weld points. The 3-dimensional information obtained from the vision system made it possible to generate the weld torch path and to obtain the information such as width and depth of weld line. In this study, a neural network based on the generalized delta rule algorithm was adapted for the process control of GMA, such as welding speed, arc voltage and wire feeding speed.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.4
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• pp.84-92
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• 1998

A program was developed to analyze the electrical characteristics and harmonic distrotion in a two-dimensional silicon BJT. The finite difference equations of the small signal and its second and thired harmonics for basic semiconductor equations are formulated treating the nonlinearity and time dependence with Volterra series and Taylor series. The soluations for three sets of simultaneous equations were obtained sequantially by a decoupled iteration method and each set was solved by a modified Stone's algorithm. Distortion magins and ac parameters such as input impedance and current gains are calculated with frequency and load resistance as parameters. The distortion margin vs. load resistancecurves show cancellation minima when the pahse of output voltage shifts. It is shown that the distortionof small signal characteristics can be reduced by reducing the base width, increasing the emitter stripe length and reducing the collector epitaxial layer doping concentration in the silicon BJT structure. The simulation program called TRADAP can be used for the design and optimization of transistors and circuits as well as for the calculation of small signal and distortion solutions.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.119-128
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• 1995

We report hybrid and passive mode-locking results of tilted-stripe AlGaAs semiconductor laser traveling wave amplifiers with saturable absorbers. Dependence ofthe pulse width on the mode locking frequency, the bandwidth of spectral filters, and the bias current of the laser amplifier are investigated. We generate 4 ps optical pulses by using the hybrid mode locking technique. The repetition rate and the peak power of generated pulses are 516 MHz and 170 mW, respectively. The tuning range of uor mode locked laser is 10 nm with the center wavelength of 780 nm. We also generate 2.6 ps optical pulses with peak power of 830 mW by using the passive mode locking technique.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.159-165
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• 1995

A double-heterostructure mesa-stripe-geometry laser diode integrated with thermoelectric Peltier cooler has been designed and fabricated. Epi-layers have been grown by metal organic chemical vapor deposition(MOCVD) method. Peltier cooling effect has been measured for devices with a mesa width of 14$\mu$m and a cavity length of 380$\mu$m. The effects of thermoelectric cooling could be shown by measuring the optical output of the laser with the increase of the current in the thermoelectric cooler. While the input courrent of the laser was maintained at 250mA, the optical output was decreased from 4.8mW to 3.8mW due to heating, but with the thermoelectric cooler on the optical output power was recovered by more than 40%. The results show that the complicated cooling device is not needed since the cooling can be achevied by the developement of the fabrication processing.

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.139-143
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• 1991

GRIN-SCH quantum well structured Laser Diode were fabricated using MOCVD and operated as CW at room temperature. The threshold current density of the LD with 670${\mu}{\textrm}{m}$ cavity length was 530 A/$\textrm{cm}^2$. For the ridge waveguide type index guiding structured LD with 6${\mu}{\textrm}{m}$ stripe width and 240${\mu}{\textrm}{m}$ cavity length, the threshold current was 50㎃. The maximum differential quantum efficiency was 0.95W/A when the optical output was 60mW. The lasing wavelength of QW LD was 865nm. In the L-I measurement. TE mode was superior to TM mode. From the near field pattern, single lateral mode operation was observed.

• Journal of Welding and Joining
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• v.19 no.6
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• pp.600-607
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• 2001

A CCD camera with a laser stripe was applied to realize the automatic weld seam tracking in GMAW. It takes relatively long time to process image on-line control using the basic Hough transformation, but it has a tendency of robustness over the noises such as spatter and arc light. For this reason. it was complemented with adaptive Hough transformation to have an on-line processing ability for scanning specific weld points. The adaptive Hough transformation was used to extract laser stripes and to obtain specific weld points. The 3-dimensional information obtained from the vision system made it possible to generate the weld torch path and to obtain the information such as width and depth of weld line. We controled the wire feeding rate using informations of weld line.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.12
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• pp.91-100
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• 1995

This paper represents the lateral first-order mode characteristics for the semiconductor laser diodes using a two-dimensional numerical simulator. In order to analyze the lateral first-order mode characteristics, Helmholtz wave equation is solved twice for the lateral fundamental and the first-order mode considering the mode gain, total losses, and the recombination rate due to the stimulated emission radiation for the each mode independantly. Through this procedure, we find that the lateral first-order mode was easily guided as increasing the stripe width for the index-guiding structures, and that the lateral first-order mode seems to be dominated in the distribution of total light intensity when its output power reaches nearly half of that of the lateral fundamental mode. This results may be used to design the device structure which guides only the lateral fundamental mode.