• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.77-82
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• 2003

A parametric study was conducted on pressure drop in a catalytic converter for automobile. In this work, we proposed a new pressure drop relation which contains the various parameters needed to calculate and got a few results. In a monolith of catalyst, the flow originally turbulent flow changes to laminar flow and thus the pressure drop through the monolith is linearly proportional to the velocity. The exhaust pressure is doubly affected by the increase of mean velocity and length when we decrease the diameter of monolith while the volume keeps constant. Theoretical parameters such as $\alpha$ and $\beta$ are suggested to use as a reference value when there is no a experimental data. Especially in the part load test, these values should be modified to consider the property change of exhaust gas.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2012.05a
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• pp.11-11
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• 2012

차나무(Camellia sinensis (L.) O.Kuntze)는 열대, 아열대, 온대지역에서 자라는 교목 또는 관목의 영년생 상록수이다. 차는 초기 약효에 의하여 이용하기 시작하였으나 현대에 이르러 그 독특한 풍미로 인하여 전 세계 인구의 절반 이상이 음용하는 중요한 기호음료이다. 강우량이 많고 따듯한 곳에서 생육이 왕성한 차나무는 현재 한국, 중국, 일본, 동남아시아의 온난지역, 남아메리카, 아프리카 및 러시아 등지에 이르는 넓은 지역에 분포하고 있다. 2,000년의 역사를 가지는 한국의 차산업은 주로 경남과 전남, 전북, 제주 등지에서 재배 생산되고 있다. 1970년대 이후 생활수준의 향상과 함께 점차적으로 수요가 늘어나면서 생산량은 1970년 55톤에서 1993년 617톤, 2010년 3,586톤으로 약 65배 이상 증가하였다. 차산업은 찻잎을 원료로 한 생활용품 등 다양한 가공품의 생산과 문화산업, 관광산업까지 포함하는 고부가가치 작목으로 매년 재배 면적이 크게 증가하였다. 최근에는 재배면적의 급속한 증가와 수입확대, 소비환경의 변화로 산지 재고가 증가하는 등 녹차 재배 농가의 어려움이 가중되고 있어 향후 수급 불균형이 우려되고 있다. 세계의 차 무역량은 연간 약 160만 톤, 재배면적은 약 256만 ha, 생산량은 약 320만 톤에 달한다. 아직까지는 수입 녹차에 대한 높은 관세율(514%)의 보호 아래 있지만, 중국이나 일본 등에 비해 가격, 품질, 상품개발 면에서 뒤떨어져 있는 실정이다. 또한 현재 외국에서 수입되고 있는 다양한 차들이 소비자의 기호에 영향을 미치고 있으며 특히 가격 경쟁력이 떨어지는 상황이다. 향후 차시장의 전면적인 개방에 대비하기 위해서는 경쟁력 있는 수출전략과 함께 국내 산업을 안정적으로 성장시키기 위한 전력을 모색해야한다. 주요 차생산국의 다원은 15도 이내의 경사지에 생성되어 있으나 30도 내외의 경사지도 다원 조성에 무리가 없다. 우리나라는 약 200만ha의 경사지를 포함하고 있어 차재배지 확대에 무한한 잠재력을 가지고 있다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.18 no.3
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• pp.42-51
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• 1981

Boron was predeposited into p (100) Si wafer at 94$0^{\circ}C$ for 60minutes to make the back surface field. High tempreature diffusion process at 1145$^{\circ}C$ for 3 hours was immediately followed without removing boron glass to obtain high surface concentration Back boron was annealed at 110$0^{\circ}C$ for 40minutes after boron glass was removed. N+ layer was formed by predepositing with POCI3 source at 90$0^{\circ}C$ for 7~15 minutes and annealed at 80$0^{\circ}C$ for 60min1es under dry Of ambient. The triple metal layers were made by evaporating Ti, Pd, Ag in that order onto front and back of diffused wafer to form the front grid and back electrode respectively. Silver was electroplated on front and back to increase the metal thickness form 1~2$\mu$m to 3~4$\mu$m and the metal electrodes are alloyed in N2 /H2 ambient at 55$0^{\circ}C$ and followed by silicon nitride antireflection film deposition process. Under artificial illumination of 100mW/$\textrm{cm}^2$ fabricated N+PP+ cells showed typically the open circuit voltage of 0.59V and short circuit current of 103 mA with fill factor of 0.80 from the whole cell area of 3.36$\textrm{cm}^2$. These numbers can be used to get the actual total area(active area) conversion efficiency of 14.4%(16.2%) which has been improved from the provious N+P cell with 11% total area efficiency by adding P+ back.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.1
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• pp.62-70
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• 1984

N+NPP+ HLEBSF (high low emitter back surface field) solar cells which have N+N high low junction in the emitter as well as N+PP+ BSF cells were designed and fabricated by using <111> oriented P type Si wafers with the resistivity of 10$\Omega$/$\textrm{cm}^2$ and the thickness of 13-15 mil. Physical parameters (impurity concentration, thickness) at each region of N+PP+ and N+NPP+ cell were made equally through same masks and simultaneous process except N region of HLEBSF cell to investigate the high low emitter junction effect for efficiency improvement. Under the light intensity of 100 mW/$\textrm{cm}^2$, total area (active area) conversion efficiency were typically 10.94% (12.16%) for N+PP+ BSF cells and 12.07% (13.41%) for N+N PP+ cells. Efficiency improvement of N+NPP+ cell which has high low emitter Junction structure is resulted from the suppression of emitter recombination current and the increasement of open circuit voltage (Voc) and short circuit current (Ish) by removing heavy doping effects occurring in N+ emitter region.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.5
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• pp.73-81
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• 2008

The purpose of this study is to create a database of the use of landscape greenery that surrounds commercial buildings in Seoul. The method of this study was: to review preceding studies and related laws, survey areas, measure trees, and analyze the results. The 20 representative sites were specifically investigated to measure the width, direction, and environment of planting conditions. To analyze the greens adjacent to the building, the greens were divided into three types: front greenery, side greenery, and rear greenery. The study surveyed the distance from trees to adjacent buildings, and their planting conditions. The results of this study are as follows. First, 45% of the front greenery and 30% of the rear greenery were not established, but 19 of the 20 side greens were. Second, 13 of the 44 green areas adjacent to commercial buildings were under 1m in width. Most side greenery was belt -shape and unrelated to the features of the site or building. Third, the average distance from trees to buildings was 0.76m, indicating that most trees were planted too close to the buildings. Fourth, of the 30 trees utilized, the species breakdown was: 8 evergreen trees, 15 deciduous trees, and 7 shrubs. For the most part, planting patterns were similar for all species. Fifth, most sites were ill-suited to tree growth, because crown shape, planting conditions, and light conditions, etc., had not been considered. Based on these results, it is suggested that more specific, subdivided standards for planting conditions should be established. For example, building plans should include a green area that is at least one meter in width. In addition, according to the location and type(closing/opening) of the greenery adjacent to the buildings, suitable management programs and supervision protocol should be adopted.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.3
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• pp.1-20
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• 2023

The present study has monitored the changes in the biodiversity of Dunchon-Dong ecological and landscape conservation area after the restoration of the wetland, identified and analyzed the threats to the ecosystem, and presented a management plan accordingly. In this area which was forests and rice paddies in the past, apartment reconstruction is currently underway, with some hinterland forests and wetlands remaining. When we look into the change in the floras, the total number of species was 193 in 2000 before the restoration, it decreased from 2004 to 2006, and as of 2019, it was 149, showing an increasing trend. The result of comparing the species that emerged before and after the restoration showed an increase in Cyperaceae herbs such as Carex maximowiczii and Carex dispalata growing in wetland areas within forests and Schoenoplectiella juncoides and Schoenoplectus tabernaemontani growing in areas within wetlands where shallow water is maintained. As a result of analyzing the change in the area ratio of each type of extant vegetation, the wetland native herbs formed the power at the highest ratio after the restoration. The change in the power of the wetland native herbs was on an increasing trend until 2007, after which it decreased much in 2010 and then gradually increased, showing values of 26.6% in 2000, 44.6% in 2002, 49.0% in 2005, 53.3% in 2007, 28.7% in 2010, and 37.3% in 2019. The cause of the decrease in 2010 was judged to be due to the vegetation management conducted to secure open water and remove organic matter in freshwater reservoirs. The amphibia which emerged from 2000 to 2019 was a total of 9 species including Hynobius leeshii, Bufo gargarizans, Kaloula borealis, and Rana uenoi. As a result of the changes in the emerging wild birds, the species diversity index before the restoration was 0.9922 in 2000, and the species diversity index after the restoration gradually increased to 1.2449 in 2005, 1.2467 in 2010, and 2.2631 in 2019. The amphibia and wild birds inhibiting in the Dunchon-Dong forest and wetland were judged to have increased through continuous wetland maintenance such as naturalized plant removal management, native plant maintenance, and open water securing management. For the ecosystem preservation management of the Dunchon-Dong ecological and landscape conservation area, it was suggested to minimize the impact of the Dunchon-Dong reconstruction project, reorganize the indiscriminate access roads adjacent to the wetland, and reorganize the main entrance to the wetland. For ecosystem restoration management, systematic restoration and ecological buffer planting were suggested to be carried out at the time of construction fence demolition.

• Korean Journal of Heritage: History & Science
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• v.48 no.2
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• pp.120-141
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• 2015

This paper is a preliminary study of architectural characteristics of Jangdae (general's podium), which shows one of the technical changes in fortification of Joseon Dynasty. As a facility for commands of generals and training for officers and men, it was located inside a fortress. Although it is not certain when the first Jangdae was built, the number of them dramatically increased around 18th century. Since the top priority function of the Jangdae was the prospect, it was installed at the hilly spot with open architecture. In addition, the open structure of Eupseong fortress towers on the riverside banks could simultaneously offer the functions as viewing around and Jangdae. Since Jangdae was also a place for military drills and reviews of soldiers, a wide podium was positioned at the front to muster the soldiers. This feature was standardized in the space organization of Jangdae in Joseon, and a mere podium was installed unless the topographic restrictions allows enough space. On the other hand, as a place for a commander, the hierarchy of the Jangdae was revealed through a variety of architectural characteristics. The hierarchy was assigned to the commander's space through the altitude difference, and diverse ornaments were added to show a sense of class. The floor plan of the Jangdae building can be largely categorized into rectangle and square, and the typical sizes of the former are $5{\times}4$ Kans (traditional measuring unit between two columns) and $3{\times}2$ Kans. Out of these two types, buildings of $5{\times}4$ Kans were found in flat land and eupseong fortresses with large space, and the relatively smaller ones of $3{\times}2$ Kans in mountain fortresses. All buildings of square floor plan had $3{\times}3$ Kans style, and the center Kan was twice wider than the side Kan to make the central space wide. It seems that the purpose was to secure the interior space of the upper story because the center Kan accounts for the floor area of the upper story. Some Jangdae's had internal story to form overhead space. The multi-roofed tower style with eaves attached to the upper and lower story is found exclusively in Jangdae. The buildings shows the Onkanmulim style which extends Naejinju (inner column) of the lower story to be the Byeonju (outer column) of the upper story, and the log-framed floor in the upper floor was structured by inserting the Changbang (connecting beam) between the Naejinju's and joining the log frames. In addition, the towers in eupseong fortresses had log-framed floor in the upper floor by setting up the high Nuhaju (column underneath a roof) and joining Cheongbang to the upper part of the column while it cannot be regarded as multi-roofed because only the upper part has a roof.