• Journal of Power System Engineering
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• v.9 no.1
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• pp.82-88
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• 2005

This paper presents numerical study on dynamic characteristics of evaporator to control evaporator superheat and compressor capacity with optimum condition in refrigeration system. It is very important to reduce energy consumption and to keep room temperature within a very restricted range with minimum oscillation in some special applications of the refrigeration system. Heat exchange is mainly happened in the evaporator. So, making mathematical model of evaporator and analyzing evaporator characteristics are necessary in order to control the superheat and the capacity of the system. A mathematical model based on the one dimensional partial differential equations representing mass and energy conservation and a tube-wall energy is described. A set of ordinary differential equation is formulated by integrating separately over the two regions(two-phase and vapor) generally presented in a heat exchanger.

• Journal of Mechanical Science and Technology
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• v.17 no.5
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• pp.766-775
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• 2003

The intermittent spray characteristics of a multi-hole diesel nozzle with a 2-spring nozzle holder were investigated experimentally. Without changing the total orifice exit area, the hole number of the multi-hole nozzle varied from 3 (d$\_$n/=0.42 mm) to 5 (d$\_$n/=0.32 mm). The time-resolved droplet diameters of the spray including the SMD (Saute. mean diameter) and the AMD (arithmetic mean diameter), injected intormittently from the multi-hole nozzles into still ambient ai., were measured by using a 2-D PDPA (phase Doppler particle analyze.). The 5-hole nozzle spray shows the smaller spray cone angle, the decreased SMD distributions and the small difference between the SMD and the AMD, compared with that of the 3-hole nozzle spray. From the SMD distributions with the radial distance, the spray structure can be classified into the three regions : (a) the inner region showing the high SMD distribution , (b) the mixing flow region where the shea. flow structure would be constructed : and (c) the outer region formed through the disintegration processes of the spray inner region and composed of fine droplets. Through the SMD distributions along the spray centerline, it reveals that the SMD decreases rapidly after showing the maximum value in the vicinity of the nozzle tip. The SMD remains the constant value near the Z/d$\_$n/=166 and 156.3 for the 3-hole and 5-hole nozzles, which illustrate that the disintegration processes of the 5-hole nozzle spray proceed more rapidly than that of the 3-hole nozzle spray.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.1.1-4
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• 1995

In this study, PLZT thin films in AFE region prepared by sol-gel processing were investigated. And PLZT stock solutions were spin-coated on ITO-glass. The PLZT thin films were annealed by RTA. Hysteresis curves, dielectric characteristics and optical transmittances were measured in order to investigates the characteristics far the thin films. The PLZT thin films were crystallized at 750$^{\circ}C$ for 5 mimutes by RTA and the rosette structure composed of perovskite observed in the thin films. In case La content was 2/90/10 antiferroelectric-ferroelectric phase boundary was 2/90/10 PLZT thin film, and its hysteresis curve was good for application of optical information storage.

• Journal of Korean Society of Rural Planning
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• v.27 no.3
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• pp.103-116
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• 2021

In this study, the characteristics of rural tourism image perceived by urban residents were analyzed through text analysis of blog data. In order to examine the images related to rural tourism, blog data written with the keyword "Gochang-gun travel" was used. LDA topic analysis, one of the text mining techniques, was used for the analysis. In the tourism image of Gochang-gun, 9 topics were derived, and 112 major places appeared. This was divided into 3 main activities and 5 object spaces through the review of keywords and the original text of blog data. As a result of the analysis, the traditional main resources of the region, Seonun mountain, Seonun temple, and Gochang-eup fortress, formed topic. On the other hand, world heritage such as dolmen and Ungok wetland did not appear as topic. In particular, the farms operated by the private sector form individual topics, and the theme farm can be seen as an important resource for tourism in Gochang-gun. Also, through the distribution of place keywords, it was possible to understand the characteristics of travel by region and the usage behavior of visitors. In the case of Gochang-gun, there was a phenomenon in which visitors were biased by region. This seems to be the result of Gochang-gun seeking to vitalize local tourism focusing on natural, ecological, and scenic resources. It is necessary to establish a plan for balanced regional development and develop other types of tourism resources. This study is different in that it identified the types and characteristics of rural tourism images in the region perceived by visitors, and the status of tourism at the regional level.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.5
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• pp.15-21
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• 2004

In this paper a new structure of BJT is proposed to improve the saturation voltage characteristics so that it can be used to the low power switching devices. In the case of the conventional finger transistor(FT), the saturation voltage is so high that it dose not satisfy the requirements for the low power device. So the other multi base island transistor(MBIT) is suggested and its saturation voltage is so low in the region of low current that it satisfy the requirement for the low power switching devices, but in region of the high current the saturation voltage tends to increase so that it does not satisfy the requirements for the low power switching devices. So in this paper a new structure of folded back electrode transistor(FBET) is proposed and the characteristics is investigated. When the new structure is applied the emitter area is increased by 35 % so the saturation voltage is reduced by 30 % at the low current region and the contact area is increased by 92 % so the saturation voltage is reduced by totally f % at the high current region with the reduction of 30 % by the increase of the emitter area and the reduction of 7 % by the increase of the emitter contact area.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.499-505
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• 2003

This paper proposes methods to extract face elements and facial characteristics points for face recognition. We select a candidate region of the face elements with geometrical information between them inside the extracted face region with skin color and extract them using their inherent features. The facial characteristics to be applied to face recognition is expressed with geometrical relation such as distance and angle between the extracted face elements. Experiment results shows good performance to extract of face elements.

• Journal of Ocean Engineering and Technology
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• v.17 no.4
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• pp.23-30
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• 2003

This study investigates the seasonal variation and spatial distribution characteristics of pollutant load, as executing the quality valuation of pollutant load inflowing into Yeong-il Bay from on-land including the Hyeong-san River. Annual total pollutant generating rate from Yeong-il Bay region are 202ton-BOD/day, 620ton-SS/day, 42ton-TN/day, and 16ton-TP/day, respectively. Particularly, the generating ration of the pollutant loads from the Hyeong-san River is greater than that of any other watershed of the Yeong-il Bay, of which BOd is about 78.2％, SS 88.5％, T-N 62.5％, T-P 73.1％, As calculating Tank model with input value of daily precipitation and evaporation of 2001 year in drainage basin of the Hyeong-san River, the estimated result of the annual river discharge effluence from this river is 830106㎥, As a result to estimating annual effluence rate outflowing at the rivers from each drainage basin. annual inflow pollutant rates are 10,633ton-BOD/year, 19,302ton-SS/year, 15,369ton-TN/year, 305ton-TP/year, respectively. The population congestion region of the Pohang-city is a greater source of pollutant loads than the Neang-Chun region with wide drainage area. Therefore, the quantity of TN inflowing into Yeong-il Bay is much more than T-P. The accumulation of pollutant load effluenced from on-land will happen at the inner coast region of Yeon-il Bay. Finally, We would make a prediction that the water quality will take a bad turn.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.145-148
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• 2002

A study on image searching and management techniques is actively developed by user requirements for multimedia information that are existing as images, audios, texts data from various information processing devices. We had been studied an automatical shape region segmentation method using color. distribution and edge characteristics of moving images for. contents-base description. The Proposed method uses a color information quantized on human visual system and extracts overlapped regions to be matched by using edge characteristics of the image frame. The performance of the proposed method is represented by similarity for comparison to a segmented image and original image.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.50-52
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• 2007

In the present paper, some difficulties encountered in predicting airfoil characteristics are described and solutions for those problems are discussed Since drag is determined by the amounts of pressure and, especially, shear stress, accurate estimation of shear stress is very crucial. However shear stress computation is dependent on the grid density and turbulence model, it should be consistent in preparing grid and turbulence model. When the transition from laminar to turbulent happen at the middle of airfoil, CFD solver should divide the region into laminar and turbulent region based on the transition location.

• Journal of Mushroom
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• v.12 no.3
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• pp.145-153
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• 2014

Pleurotus has increased rapidly production and consumption because of highly nutritional value, natural healthy food and so on. The basic studies for Pleurotus need for development of mushroom industry. This study was to investigate the cultural characteristics among 15 strains of 6 species and to analyze their phylogenetic relationships. The cultural characteristics were investigated by mycelial growth activity at different media, temperature and pH. The optimum media for mycelial growth were YM and MCM in most species. The optimum temperature for mycelial growth were $25^{\circ}C$ and $30^{\circ}C$. The optimum pH for mycelial growth were widly range from pH 5.1 to 7.4. Through the RFLP (restriction fragment length polymorphism) of IGS (intergenic spacer) I region in ribosomal DNA, it was analyzed phylogeny of interspecies and intraspecies. Each species was discriminated well as isolates within each species formed clade to be distinguished other species. P. florida was highly similar to P. floridanus, and P. flabellatus was P. cornucopiae. P. fuscus var. ferulae was highly similar to P. eryngii but discriminated different species in analysis of RFLP of IGS I region and showed different characteristics in mycelial culture. RFLP of IGS I region was useful of studying phylogenetic relationships of species and population.