• 전자공학회논문지D
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• 제35D권4호
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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.

• 전자공학회논문지A
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• 제32A권1호
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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.

• 한국컴퓨터산업학회논문지
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• 제5권2호
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• pp.293-300
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• 2004

본 논문에서는 MPEG 스트림에 대하여 VCR과 같은 기능을 제공하고 저장 공간을 최소화하는 알고리즘을 제안하였다. 특히 MPEG 스트림을 여러 개의 디스크에 효과적으로 스트라이핑 하는 방법과 전체 디스크에 걸쳐 분산되어 있는 스트림을 검색하기 위한 접근방안을 제안하였다. 제안된 알고리즘에 대한 실험을 통하여 VOD 서버가 FF/FB기능을 제공하는 경우에 필요한 추가적인 저장 공간을 감소시킬 수 있음을 확인하였다.

• 한국CDE학회논문집
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• 제14권1호
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• pp.10-17
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• 2009

Surface detection and parameter estimation in point cloud is a relevant subject in CAD/CAM, reverse engineering, computer vision, coordinate metrology and digital factory. In this paper we present a software for a fully automatic surface detection and parameter estimation in unordered, incomplete and error-contaminated point cloud with a large number of data points. The software consists of three algorithmic modules each for object identification, point segmentation, and model fitting, which work interactively. Our newly developed algorithms for orthogonal distance fitting(ODF) play a fundamental role in each of the three modules. The ODF algorithms estimate the model parameters by minimizing the square sum of the shortest distances between the model feature and the measurement points. We demonstrate the performance of the software on a variety of point clouds generated by laser radar, computer tomography, and stripe-projection method.

• 조명전기설비학회논문지
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• 제26권5호
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• pp.13-20
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• 2012

The light transmittance of optical device is one of the important conditions to improve the product performance and it has researched through the various methods. One of these methods to improve the optical transmittance is to use a pattern on optical surface. The advantages of this method are to simplify the manufacturing process and to easy mass production. If a surface of glass has with the proper patterns, we can expect a great effect on optical transmittance. The purpose of this research is to derive a pattern to get high transmittance from a theoretical approach and to analyze the transmittance through the simulation. And then, we made a sample with a pattern and compared with the results from simulation and experiment.

• 대한원격탐사학회지
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• 제23권1호
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• pp.55-58
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• 2007

The prototype radiometric calibration algorithm of the imagers for IR channels has been developed according to the Weinreb's method. Applying the algorithm to the GOES-12 count data, we have shown that the calibration coefficients (slope and intercept) evaluated by the algorithm gives good agreement with the NESDIS's ones, and that the scanning error due to the scan mirror emissivity and stripe error are almost eliminated by the East/West angle dependent scan-mirror correction and the respective calculation of intercept for each North/South scan line, respectively.

• Journal of Ceramic Processing Research
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• 제13권spc1호
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• pp.93-95
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• 2012

We report on the growth and characterization of the nano- and micro scale GaN structures selectively grown on the vertex of GaN stripes using the metal organic vapor phase epitaxy method and conventional photolithography technique. The triangular shaped nano- and micro GaN structures which have semi-polar {11-22} facets were formed only on the vertex of the lower GaN stripes. Crystalline defects reduction was observed by transmission electron microscopy for upper GaN stripes. We also have grown the InGaN/GaN multi-quantum well structures on the semi-polar facets of the upper GaN stripes. Cathodoluminescence images were taken at 366, 412 and 555 nm related to GaN band edge, InGaN/GaN layer and defects, respectively.

• Journal of the Optical Society of Korea
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• 제19권1호
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• pp.29-37
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• 2015

The wavefront printer records a volume-reflection hologram as a two-dimensional array of elemental holograms from computer-generated holograms (CGHs) displayed on a spatial light modulator (SLM). The wavefront coming from the object is extracted by filtering in the spatial-frequency domain. This paper presents a method to improve color reproduction in a wavefront printer with spatial division of exposures at primary colors, by adaptive partitioning of the SLM in accordance with the color content encoded in the input CGHs, and by the controllable change of exposure times for the recording of primary colors. The method is verified with a color wavefront printer with demagnification of the object beam. The quality of reconstruction achieved by the proposed method proves its efficiency in eliminating the stripe artifacts that are superimposed on reconstructed images in conventional mosaic recording.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1999년도 KOBA 방송기술 워크샵 KOBA Broadcasting Technology Workshop
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• pp.227-232
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• 1999

We have been making researches on 3-D displays using computer-generated holograms(CGHs). Our CGHs are binary Fresnel holograms that reconstruct point light sources and are recorded by using high resolution laser printers (image setters). We use an image setter with a resolution of 5080 dots per inch. It is possible to reconstruct CGHs with light-emitting points. As the resolution of the image setter is not so high, it is better to use a spherical wave as a reference beam. We considered the recordable points objects are restricted by the low resolution, and proposed the multiplex type hologram to reduce the number of point objects recorded in the unit area of the CGH. We proposed a method to make computer-generated color hologram which could reconstruct color point light sources, by combining RGB color filters with the stripe CGHs corresponding to each color. We considered two kinds of gradation method on our binary CGHs. In this paper, we propose a multiple reconstruction method for improving the narrow viewing field.

• 복식
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• 제52권1호
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• pp.129-143
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• 2002

Patterns are something that comes out of necessity in human life, which is closely associated with it. Thus come the SFAA (Seoul Fashion Artists Association) collection which uses patterns varying in form, color, way of expression and material. For this research, I first categorized the patterns the SFAA designers used into: natural patterns, symmetric patterns, traditional patterns, stripe, plaid, dot and abstract patterns. As a result of the process. the designers most favored the natural patterns and symmetric patterns, and dot patterns were rarely used. The designer who most favored patterns in general was Sul Yun-hyoung, and the designer Kim Chul-ung rarely favored the surface effect. The seven kinds of patterns naturally differ according to the designer. as Park Hang-chi liked to use the plaid patterns along with yam dyeing material, whereas Jin Teok expressed stripe patterns using the yarn dyeing fabric. Natural patters were presented in a bizarre way with Lie Sang-bong. who took the motives appearing in Eastern ceramic and paintings into the clothes, using the print method. The symmetric patterns, which the SFAA designers most preferred. was used evenly among designers like Chang Kwang-hyo, Gee Choon-hee. Rubina, and Haneza. In contrast. Lie Sang-bong. who used abstract patterns that do not give out meaning of the actual form of the pattern. rarely used symmetric patterns. The dot patterns were most often used by Park Youn-soo. and traditional patterns were overwhelmingly chosen by Sul Yun-hyoung. Secondly. in expressing the colors, SFAA designers were much more likely to choose achromatic colors. not choosing to show off colors. This is especially apparent in works by Haneza and Lie Sang-bong. In the SFAA collections, numerous methods were used to create. For instance, Sul Yun-hyoung used the oriental embroidery method. and Rubina and Lie Sang-bong used many unique dying methods. In terms of materials, Sul Yun-hyoung preferred silk. due to her methods, and Lie Sang-bong was one of the designers that used a number of different materials such as vinyl. Jacques Mueclier of the Paris Clothes Association in France, who was invited to SFAA collection once, remarked. "While the choice of material and the actual sewing done were excellent, there lacked much difference among the designers, as most of them choose flowing silhouette In terms of composition," which is all too correct. In addition, there were cases in the collection where the inherent feelings of cultural artifacts was expressed without alteration. Summing up, the research aimed to analyze the surface expression methods, forms and color of SFAA designs. and I hope that it can open up ways for new projects in the future.he future.