• Journal of the Korean School Mathematics Society
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• v.21 no.4
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• pp.401-418
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• 2018

The current geometric and vector textbooks focus on the mechanical activities of finding focus, corner, etc. through elliptic equations. In this paper, we propose a process in which analogy and analytical methods are used in reversible activities of focusing from a given elliptic graph without a coordinate plane. The exploratory tool was used as Geogebra. At first, students tried to find the focus of the ellipse by randomly constructing the major a is and the minor a is in the given ellipse. However, we have experienced a method of constructing the circle of symmetry and analyzed this principle and deduced it to the ellipse. As a result, we could construct the center, long a is and short a is of the ellipse. Then, using the analytical method, the focus formula was recognized as the Pythagorean theorem, and the ellipse's focus was constructed by using the original drawing. Therefore, it is confirmed that analogy and analytical method can positively affect the elliptical focus.

• Composites Research
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• v.31 no.6
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• pp.347-354
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• 2018

Shape memory polymer composites have been studied for deployable antennas in space because they have advantages of lightweight, large deformability, good processability, and low cost. In this research, shape memory polymer composites (SMPCs) were manufactured using carbon nanotubes (CNTs) as reinforcements and were used to fabricate SMPC antenna. The SMPCs were prepared by dispersing CNTs in the polymer matrix. Various dispersion methods were investigated to determine the most suitable one, focusing on the mechanical properties of SMPCs including their fracture behavior. The shape memory properties of SMPCs were measured and finally, the deployment behavior of the SMPC antenna was analyzed.

• Korean Journal of Environmental Agriculture
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• v.24 no.1
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• pp.29-33
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• 2005

To develop proper soil management practices for reducing soil erosion, experiments were carried out by using lysimeters in Pyeongchang highland, Korea. Lysimeters installed at Hoenggye bad 13% slope, 15 m slope length and 3 m width. Lysimeters with 23% slope, 15 m slope length and 3 m width were also installed at Yongsan. Soil textures in Hoenggye and Yongsan lysimeter plots were silty clay loam and sandy loam, respectively. In the lysimeters potato was cultivated, and slant furrow culture and contour culture were applied. Up-down furrow and continuous fallow lysimeter was included in the experiments as a control plot. For the slant furrow and contour culture methods, minimum furrow mulching and gravel barrier were placed at each end of the furrows in the lysimeters from April to October in 2000 and 2001 to prevent soil and nutrient losses. In Heonggye, in two years experiments, average soil loss of 17 Mg/ha was found in the up-down and continuous fallow lysimeter and 2.6 Mg/ha from furrow minimum straw and slant furrow treatment, and 1.8 Mg/ha from slant furrow and gravel bag treatment. In the contour culture, the soil losses were further reduced. In Yongsan, soil loss in the slant furrow culture without any protection treatment was 167 Mg/ha, and the soil loss was reduce to 61 and 86 Mg/ha with minimum straw and gravel bag treatments, respectively. The soil loss could be reduced more than 45% by furrow minimum straw and gravel barrier. The furrow minimum straw or gravel bag barrier successfully reduced soil loss in clay loam soil in Heonggye, but still the treatments were not enough to reduce soil loss in saprolite piled sandy loam soil in Yongsan.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.2
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• pp.126-138
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• 2012

The purpose of this study is to evaluate the imbalance of green space using various spatial analysis methods and to establish the management zone for green space with service supply in the aspect of its use in Daegu. The total green space of Daegu is 48,936.1ha which is the second among 7 metropolitan cities of Korea. According to the imbalance analysis of green space, the Gini's coefficient based on the area was not high, on the other hand, the Gini's coefficient based on the population was high by above 0.6. According to an evaluation of service supply of green space in Dalseo-gu, the area within about 100m around large green space was supplied with green spaces of above $25m^2$/pop. On the other hand, the area such as Sangin, Jukjeon, and Yongsan was not almost supplied with green space. Finally, 'Rich zone', 'Fair zone', 'Poor zone', and Broken zone' could be established based on the service supply for the management direction of green space. The findings from this study can be used as the basic data for selecting the construction priority of new green spaces.

• Journal of the Korean Institute of Landscape Architecture
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• v.41 no.6
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• pp.158-170
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• 2013

With the recent 'Creative economy' and 'Cultural prosperity' coming to the fore as a new code to build up a city or a region, it is necessary to focus on strengthening the regional creative capacity as well as developing spontaneous regional culture. In such trend this research aims to explore the Kyunglidan-gil, Seoul, Korea in which creative-class are appearing autogenously in clusters and forming new cultural landscape, to identify the factors of their accumulation and changing aspect of cultural landscape. This study has the following purposes: First, Investigating the historical context of the Kyunglidan-gil's landscape. Second, considering the process of the creative-class being flowed into the Kyunglidan-gil as the subject leading to the modification of the region. Third, their activity was analyzed to consider the unique aspect of forming the cultural landscape at the Kyunglidan-gil. Regarding why the creative-class should flow in, results of the study drew five factors including region in issue compared to inexpensive rents, coexistence with nature, quiet atmosphere seeming isolated from the urban confusion, location possible to test and share individual materials one likes, and a site with synergy effect of activity through the network with acquaintances. Also, five characteristics of cultural landscape forming by the people's activity were drawn - space of communication for increasing creativity, temporary and flexible spatial use, expression of one's identity and taste, distinguishing, and positive use of the existing facilities. Like this, by exposing the 'creative-class', a subject of the leader in changing process of the Kyunglidan-gil, this research identified the aspect of forming cultural landscape.

• Tuberculosis and Respiratory Diseases
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• v.63 no.1
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• pp.17-23
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• 2007

Background: Many diagnostic approaches for defining the definitive cause of pleurisy should be included due to the large variety of diseases resulting in pleural effusion. Although ADA is a useful diagnostic tool for making a differential diagnosis of pleural effusion, particularly for tuberculous pleural effusion, a definitive diagnostic cut-off value remains problematic in Korea. It was hypothesized that ADA multiplied by the Lymphocyte/Neutrophil ratio(L/N ratio) might be more powerful for making a differential diagnosis of pleural effusion. Methods: One hundred and ninety patients, who underwent thoracentesis and treatment in Chung-Ang University Hospital from January, 2005 through to February 2006, were evaluated. The clinical characteristics, radiologic data and the examination of the pleural effusion were analyzed retrospectively. Results: 1. Among the 190 patients, 59 patients (31.1%) were diagnosed with tuberculous pleurisy, 45 patients(23.7%) with parapneumonic effusion, 42 patients(22.1%) with malignant effusions, 36 patients(18.9%) with transudate, and 8 patients(4.2%) with empyema. One hundred and twenty one patients were found to have an ADA activity of 1 to 39 IU/L(63.7%). Twenty-nine were found to have an ADA activity of 40 to 75 IU/L(15.3%) and 40 were found to have an ADA activity of 75 IU/L or greater(21.0%). 2. Among the patients with tuberculous pleurisy, 5(8%), 18(30%) and 36 patients(60%) had an ADA activity ranging from 1 to 39 IU/L, 40 to 75 IU/L, and 75 IU/L or greater, respectively. In those with an ADA activitiy 40 to 75 IU/L, 18 patients(62%) had tuberculous pleurisy, 9(31%) had parapneumonic effusion and empyema, and 1(3.4%) had a malignant effusion. 3. In those with an ADA activity of 40 to 75 IU/L, there was no significant difference between tuberculous pleurisy and non-tuberculous pleural effusion(tuberculous pleurisy : 61.3 ${\pm}$ 9.2 IU/L, non-tuberculous pleural effusion : 53.3${\pm}$10.5 IU/L). 4. The mean L/N ratio of those with tuberculous pleurisy was 39.1 ${\pm}$ 44.6, which was significantly higher than nontuberculous pleural effusion patients (p<0.05). The mean ADA x L/N ratio of the tuberculous pleurisy patients was 2,445.7 ${\pm}$ 2,818.5, which was significantly higher than the non-tuberculous pleural effusion patients (level p<0.05). 5. ROC analysis showed that the ADA x L/N ratio had a higher diagnostic value than the ADA alone in the group with an ADA between 40-75 IU/L. Conclusion: The ADA multiplied by the lymphocyte-to-neutrophil ratio might provide a more definitive diagnosis of tuberculous pleurisy.

• Polymer(Korea)
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• v.29 no.3
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• pp.260-265
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• 2005

The initial burst of drug release is an important role in the controlled delivery of drug having hish toxicity and narrow therapeutic ranges. Nanosphere composed of monolayer could not achieve precisely controlled drug release because of the initial burst of drug on surface. In this study, double layered nanosphere was prepared for sustained drug delivery without initial burst. Double layered nanosphere composed of dextran and PLGA was fabricated by using conventional W/O/W double emulsion method. To control surface tension on the outer layer of nanospheres, PVA was used as a surfactant. Release behavior of dextran as model drug was observed as the $3{\times}1$mm wafers formed by compression mould in the deionized water for 7 days. Double layered nanosphere has sustained release behavior, in contast to single layered nanospheres. such as mechanical mixture and dextran nanospheres. Especially, nanosphere containing PVA $0.2\%$ has shown nearly the zero-order release profile. As a result of this study, double layered nanospheres has more sustained release profile of drug without the initial burst and the release behavior of dexoan on tile double layered nanospheres was controlled by the contents of PVA as a surfactant.

• Journal of Korean Society of Forest Science
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• v.94 no.3 s.160
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• pp.135-145
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• 2005

The purpose of this study is to reveal the component characteristics and the channels of distribution for forest products as a fuel that were consumed in Kyeongseong city (Seoul) in 1929, in the middle of the colonial period. The summary of the results are as follows; (1) though the average consumption of forest products consumed as a fuel per household in Kyeongseong city was slightly less than one-third as much forest products as fuel consumed in other counties of Kyeongki province, but due to the high heat capacity, the amount of fuelwood and charcoal consumption was much higher than leaf and grass consumption; (2) the largest supply areas of forest products for fuel were the riverside of Kangwon province and Kyeonggi province in which the waterways were available. They supplied 42.6% of total consumption, and the other supply areas were the northern part of Kyeonggi province, etc. (29.5%) where railroads were handy, and the suburbs of Kyeongseong City (27.9%) by roads; (3) the transportation areas using the Han River were divided into two parts of Ttook island (43.0%) and former Yongsan and Mapo (45.6%), but the volume of transportation by railroad was centralized in Kyeongseong Station, which accounted for 72.2% of total volume of transportation by rail; (4) the most of the forest products consumed for fuel in Kyeongseoung city were sold in temporary fuelwood markets, rather than permanent and regular markets.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.3
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• pp.11-22
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• 2014

The buffer capacity of food waste lowers during the collecting and transportation period. Food waste usually shows deficiency of micro nutrients especially molybdenum(Mo) and cobalt(Co). Therefore, food waste can be considered as a good mixture of livestock waste to enhance methane production. The objective of this study was to investigate the correlation between properties of substrates (local food waste and livestock manure) and methane yields for successive anaerobic fermentation process and its stable management. Food wastes were taken at an intermediate storage or treatment system provided by eight local authorities (Gangnam, Gangdong, Gwanak, Guro, Dongjak, Songpa, Yeongdeungpo, and Younsan) in Seoul. The solid content and potential methane yield of food wastes were average of 16% and $446.6STP-m{\ell}/g-VS$ (range from 334.8 to $567.5STP-m{\ell}/g-VS$) respectively. As for the beef cattle manure, the solid content and potential methane yield had an average of 26% and $280.6STP-m{\ell}/g-VS$ respectively. Potential methane yield had a positive correlation with fat content, and hydrogen content and a negative correlation with carbohydrate content ($r^2&gt;0.8$). Therefore, the potential methane yield can be predicted based on the substrate characterization results with reasonable accuracy. Further research may be needed to investigate the relation of the properties of the mixture substrate and methane production rate. The mixtures may include food waste, livestock waste, and bulking agents (saw dust, rice hull, or agricultural byproducts etc.) to determine best combination of these substrates for maximum methane production rate.

• Journal of the Economic Geographical Society of Korea
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• v.4 no.1
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• pp.37-60
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• 2001

The record industry, which consists of the cultural industries, has been deeply interrelated with the innovations of the science and the technologies. In Korea, the record industry has been developed dramatically since the late 1980s, and thus it has formed a huge business, and has also brought a lot of accompanying economical effects. The record industry is constituted with four circulation steps such as producing, manufacturing, wholesaling and retailing, which follow the different locational orients, respectively. The purpose oi this study is to investigate the locational characteristics of each step. Because of the shortage of the data, this study based on the direct data from field studies, interviews, and surveys, as well as the existing document data. The results of this research are summarized as following: the record industry shows strong concentrations in Seoul and the surrounding areas. It also shows the spatial linkage with other industries that are necessary for the production, advertisement, and sales of records. The locations of the record producers are affected by the location of broadcasting stations. Therefore, they are concentrate in Kangnam and Yeouido, where many broadcasting stations are located.