• Journal of the Korean Vacuum Society
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• v.12 no.4
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• pp.239-250
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• 2003

The reliability degradation phenomena in the SiGe hetero-junction bipolar transistor (HBT) are investigated in this review. In the case of the SiGe HBT the decrease of the current gain, the degradation of the AC characteristics, and the offset voltage are frequently observed, which are attributed to the emitter-base reverse bias voltage stress, the transient enhanced diffusion, and the deterioration of the base-collector junction due to the fluctuation in fabrication process, respectively. The reverse-bias stress on the emitter-base junction causes the recombination current to rise, increasing the base current and degrading the current gain, because hot carriers formed by the high electric field at the junction periphery generate charged traps at the silicon-oxide interface and within the oxide region. Because of the enhanced diffusion of the dopants in the intrinsic base induced by the extrinsic base implantation, the shorter distance between the emitter-base junction and the extrinsic base than a critical measure leads to the reduction of the cut-off frequency ($f_t$) of the device. If the energy of the extrinsic base implantation is insufficient, the turn-on voltage of the collector-base junction becomes low, in the result, the offset voltage appears on the current-voltage curve.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.6
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• pp.53-66
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• 2019

The purpose of this study was to suggest indicator-based selection and improvement plans for evaluating urban regeneration projects. First, we selected the indicators by conducting expert surveys and analysis of the responses received. Additionally, using the selected indicators, we analyzed the residents' opinions in Wongogae Village, where urban regeneration projects were in progress. Based on these, we suggested a plan to improve Wongogae Village. According to the study, we classified the urban regeneration evaluation indicators into 'Physical environment', 'Social environment' and 'Economic environment' according to their characteristics. We selected urban regeneration evaluation factors through the first expert survey and MCB analysis. As a result, we selected six factors for the 'Physical environment' category: 'Traffic and pedestrian environment', 'Residential (housing) environment', 'Safety and security environment', 'Greenspace', 'Landscape improvement' and 'Public space', In the 'Social environment' category, four factors were chosen: 'Resident participation', 'Community activation', 'Role of the local government and support centers' and 'Resident education' while for the 'Economic environment' category three factors were selected: 'Local economic revitalization', 'Creating an economy-based environment', 'Job creation'. Next, we conducted a second expert survey and carried out an AHP analysis using the selected evaluation factors to derive the overall weight for each. Among the evaluation factors for urban regeneration, the 'Residential (housing) environment' has the highest weighted value of 0.108, followed by 'Local economic revitalization' and 'Resident participation'. Lastly, the analysis of the residents' opinions of Wongogae Village using the urban regeneration evaluation factors, Parking environment', 'Maintenance of old houses and living environment', 'Environment for founding town and social enterprises', 'Improve commercial and business environment', 'Maintain and activate existing business' and 'Vitalizing small regional economies such as domestic handicrafts and side-job' had high overall importance, but low satisfaction, which means that it is necessary to improve the focus. Therefore, in order to improve the urban regeneration project in villages, it is necessary to improve the parking environment by expanding public parking lots, eliminate close houses, and idle lands, or open a school playground in the village for the residents. In addition, it is essential to encourage economic activities, such as fostering village enterprises and social enterprises in connection with cooperatives and allow for the selling of the products through resident activities, such as neighboring markets.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.28 no.3
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• pp.29-38
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• 2010

A moat is a pond or waterway paved on the outside of a fortress that is one of the facilities to prevent enemy from approaching the fortress wall or classify it as the boundary space, and this study was undertaken to find out the characteristics of the moat that was existed in the East and the West from ancient time to medieval time with the following result. First, the moat in the East was installed of natural moat and artificial moat at the same time while the moat in the West had the fortress built in naturally advantageous site to use natural most substantially more. Second, the moats of Korea were smaller in scale compared to other countries (Japan, China and the Western countries). Third, the fortresses in the East were built to protect towns or royal palace while the West had the fortress to protect the residence of kings, lords, great wealthy persons and the like, and they were used jointly with the natural moat and artificial moat to defend against the infiltration of enemy. Fourth, the Pungsujiri in the Orient is one of the numerous ideologies forming the supplementary ideologic system of Korean people that could not be denied as the perception that influences on Korean people after the Silla Dynasty, and this Pungsujiri was considered when determining the location of the castle. The moat surrounding the castle had the role to keep the good energy in the castle from escaping away. Fifth, the Ha-Ha technique in the west was designed to prevent the external power from infiltration by digging the ditch on the place applicable to the boundary of the garden site, rather than the fence. While walking around along the water-side path without knowing the existence of this ditch, when the road is discovered with the cut off in the ditch, people had the exclamation without actually recognizing such astonishment. It was originally the dike for military purpose during the medieval time that was designed to look into the garden without physical boundary surrounded with the vertical fence in the garden that by having the deep ditch like shape on the boundary line of the garden which was designed to form the farm by preventing various types of cattle from coming inside the garden and bring in the garden element for farms, forestry, agricultural land and the like.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.38 no.4
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• pp.58-67
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• 2020

The present study was conducted as part of basic research for selecting species of street trees with historical value in Seoul. It also made up a list of traditional landscape trees for a variety of alternatives. The following results are shown below. As to the history of street trees in Korea, records on to-be-estimated street trees are found in historical documents written in King Yangwon during the second year of Goguryeo Dynasty (546) and King Myeongjong during 27 year of Goryeo (1197). However, it is assumed that lack of clarity is found in historical records. During the 23 year of King Sejong in the early Joseon Dynasty (1441), the record showed that the state planted street trees as guideposts on the postal road. The records revealed that Ulmus spp. and Salix spp. were planted as guidance trees. The street tree system was performed in the early Joseon Dynasty as recorded in the first year of King Danjong document. Pinus densiflora, Pinus koraiensis, Pyrus pyrifolia var. culta, Castanea crenata, Styphnolobium japonicum and Salix spp. were planted along the avenue at both left and right sides. Morus alba were planted on streets during the five year of King Sejo (1459). As illustrated in pieces Apgujeong by painter Jeongseon and Jinheonmajeongsaekdo in the reign of King Yeongjo, street trees were planted. This arrangement is associated with a number of elements such as king procession, major entrance roads in Seoul, place for horse markets, prevention of roads from flood and indication. In the reign of King Jeongjo, there are many cases related to planting Pinus densiflora, Abies holophylla and Salix spp. for king procession. Turning king roads and related areas into sanctuaries is considered as technique for planting street trees. During the 32 year of King Gojong after opening ports (1985), the state promoted planting trees along both sides of roads. At the time, many Populus davidiana called white poplars were planted as rapidly growing street trees. There are 17 taxa in the Era of Three Kingdoms records, 31 taxa in Goryeo Dynasty records and 55 taxa in Joseon Dynasty records, respectively, described in historical documents to be available for being planted as street trees in Seoul. 16 taxa are recorded in three periods, which are Era of Three Kingdoms, Goryeo Dynasty and Joseon Dynasty. These taxa can be seen as relatively excellent ones in terms of historical value. The introduction of alien plants and legal improvement in the Japanese colonial period resulted in modernization of street tree planting system. Under the six-year street tree planting plan (1934-1940) implemented as part of expanding metropolitan areas outside the capital launched in 1936, four major street trees of top 10 taxa were a Populus deltoides, Populus nigra var. italica, Populus davidiana, Populus alba. The remaining six trees were Salix babylonica, Robinia pseudoacacia, platanus orientalis, Platanus occidentalis, Ginkgo biloba, and Acer negundo. Beginning in the mid- and late 1930s, platanus orientalis, Platanus occidentalis were introduced into Korea as new taxa of street trees and planted in many regions. Beginning on 1942, Ailanthus altissima was recommended as street trees for the purpose of producing silks. In 1957 after liberation, major street tree taxa included Platanus occidentalis, Ginkgo biloba, Populus nigra var. italica, Ailanthus altissima, Populus deltoides and Salix babylonica. The rank of major street tree species planted in the Japanese colonial period had changed. Tree planting trend around that period primarily representing Platanus occidentalis and Ginkgo biloba still holds true until now.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.31 no.2
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• pp.20-30
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• 2013

'Paulownia tree', one of a tree species which has been with human civilization, has been widely used as a garden plant. The purpose of this study is to investigate concrete species of 'paulownia tree,' which had been planted in Korean traditional garden, the position of plantation, and consider its usefulness therefrom. The results of the study can be summarized as follows. 1. As the result of considering old literatures as encyclopedia, agricultural book (農書), gardening book, etc., there's a difference in the description of 'paulownia tree' depending on the complier, as well, the classification of concrete species is quite ambiguous. Therefore, it judged a limit which is planted based on point of the compass is not apply to species of tress of paulownia tree. Merely, the point of suitability and evasion(宜忌) related to the plantation of 'paulownia tree' could be identified in "Jeungbosanrimgyeongje(增補山林經濟) and "Imwongyeongjeji(林園經濟志)", not "Sanrimgyeongje (山林經濟)". 2. It could be confirmed again through poetry and prose which describe old garden that the words such as 'O(梧)', 'Dong(桐)', 'Odong(梧桐)', etc. were used without significant division. However, it is supposed that the species 'Odong' which was actually adopted at the garden might be Catalpa as well including Korean Paulownia and Chinese parasol tree. 3. It is considered that the reference point of suitability and evasion(宜忌) regarding 'paulownia tree' plantation was not generally applied. That is, species of paulownia tree was not divided for planting according to direction, as well, they seemed to willingly plant paulownia trees nearby the house as well, e.g. front yard or nearby yard, etc. 4. The usefulness of paulownia tree as a garden plant of an old garden played a role of 'the messenger of fall,' emphasizing a sense of the season. 5. Paulownia tree has another usefulness as a tree which adds an Ephemeral landscape. Therefore, the ancient people considered 'paulownia tree' that goes with 'the moon' the best, and enjoyed the quaint beauty of those two are juxtaposed. Also, 'paulownia tree' was utilized as a tree which adds an atmosphere of a rainy day, such as enjoying the sound of rain dropping on the 'paulownia tree', etc. The limitation of this study is that the research was performed being restricted to the translation among lots of Chinese references. Later-on task of research is the necessity of a more in-depth study through the discover of new historical sources and the accumulation of translation outcome.

• Journal of the Korean Institute of Landscape Architecture
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• v.46 no.6
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• pp.49-59
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• 2018

The purpose of this study was to analyze the importance and satisfaction of resources in the mouth of Nakdong River. A Pearson's chi-square test was performed in SPSS 24.0 for statistical analysis and the result of the study was summarized by three points. First, the results of importance analysis on resources in Nakdong estuary found that the importance of ecology resources was the highest with 27.1%, followed by landscape resources (18.5%), waterside leisure resources (6.5%), complex cultural resources (5.4%), and historic and cultural resources (3.3%). The probability values (p-value) of each group had shown significant differences depending on gender, age, and the location of the survey. For instance, women respondents reported a higher preference to ecology resources and complex cultural resources such as museums than men respondents as much as two times and three times, respectively. Meanwhile, men respondents showed a higher preference to waterside leisure resources in three times as much as women respondents. As for the analysis by age, the respondents in their 20s and 30s recorded a higher value than those in other age groups, and people in their 30s reported a higher preference to waterside leisure resources than those in different age groups by three times. Lastly, no significant differences were found in the preference analysis by occupation (p>.05). With regard to the results of satisfaction analysis, the average level of satisfaction on landscape resources was 6.01, and that of ecology resources and complex cultural resource were 5.65 and 5.15, respectively. Also, significant differences were found between landscape and ecology resources in the satisfaction analysis by age, landscape resources by age, ecology resources by region, and between landscape resources and ecology resources by occupation. The p-value of complex cultural resources was p=0.012, although the satisfaction level of landscape resources and ecology resources were reported to have no significant differences by age. As for the level of satisfaction in landscape resources, respondents in their 40s and 50s showed a high level of satisfaction. However, those in their 20s showed a relatively low level of satisfaction in the same category. The survey respondents living in Busan and South Gyeongsang Province and those living outside the regions revealed no significant differences in terms of satisfaction in landscape resources and complex cultural resources. However, the two same groups were found to show significant differences in the satisfaction analysis on ecology resources. In the satisfaction analysis of landscape resources and ecology resources by occupation, significant differences were found among college students, government employees, ordinary citizens, and expert groups. However, they showed no significant differences in the level of satisfaction to complex cultural resources. Third, the results of importance-satisfaction analysis on Nakdong estuary found that the average levels of satisfaction to landscape resources for each group of respondents who considered landscape, ecology, and cultural resources as important was 6.19, 6.08, and 5.67, respectively. Their levels of satisfaction on ecology resources were 5.95, 5.57, and 5.41 for each. Its correlation to the importance was insignificant. However, it was confirmed that the correlation to the level of satisfaction on complex cultural resources had a significant difference (p=0.025). In addition, the results of the analysis on 15 detailed items that was carried out with the aim to improving values and vitalizing resources in the mouth of Nakdong River found that respondents considered that the vitalization of eco-tourism (49.5%) and restoration of reed marsh (47.5%) were important. The results of detailed analysis revealed respondents' high awareness on the need of enhancing values on ecology resources. Also, improving infrastructure nearby the mouth, creating cycling routes, walkways, waterside leisure facilities, and others were considered as the requirements for the vitalization of Nakdong estuary.

• Journal of Korean Society of Forest Science
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• v.77 no.1
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• pp.1-9
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• 1988

To analyze phytosociological characteristics of the Mt. Namsan nature park, Seoul, vegetation structure of north-east and south-west slopes, competition capability among species, vegetation structures of afforested species were studied with belt-transect and quadrat methods. And management plan of each vegetational zone was proposed by the results of this study and the other previous reports. Numbers of species and individuals of south-west slope were greater than those of north-east slope. But species diversity of northeast showed stability of 1.0, while that of south-west showed instability from 0.8 to 1.3. The floristic dissimilarity coefficient between two slopes showed 70-80% in which species composition between two slopes was much different. Quercus mongolica was a dominant species at north-east slope and Pinus densiflora at south-west slope. Competition capability among major species was resulted in deciduous trees>Robinia pseudoacacia>Populus alba ${\times}$ glandulosa>Pinais densiflora, Quercus mongolica>deciduous trees>Pinus densiflora. Afforested vegetation at the Mt. Namsan, especially Pinus koraiensis, Abies holophylla, Picea abies, etc showed poor growth rate. The goal of the Nam-san nature park management is to conserve natural ecosystem as it is and, if necessary, to accerlerate restoration of the disturbed ecosytem to its nature by minimum energy input as possible. Management proposal was made for six vegetational management zone ; P. derasitZoru forest zone, Q. mongolica forest zone, deciduous forest zone, afforestation zone, R. pseduoacacia zone and landscape planting zone.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.311-321
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• 2003

We surveyed physico-chemical properties of bottom water and sediment to evaluate the influence of sediment on the eutrophication in the downstream of Nagdong River from 1998 to 2000. From May to August, DO concentration of bottom waters dropped below 5 mg $O_2/l$ and $NH_4\;^+$ and $PO_4\;^{3-}$ concentrations significantly increased in the bottom waters, resulting in the great differences between surface and bottom waters. Fluxes across water-sediment interface would be substantially active in this period. The serial orders of the water fertility or eutrophication were Joman River > Sonagdong River > Nagdong River. The organic nutrient contents of sediment increased toward the lower parts of the river system. Organic contents of the sediment would be under the influence of water pollution and exhibited a negative correlation with sediment bulk-density or particle size. The concentrations of exchangeable inorganic nutrients of sediment were greater than those of pore waters, and $PO_4\;^{3-}$, $NH_4\;^+$ and $SiO_2$ increased along the sediment depth. $PO_4\;^{3-}$ and $NO_3\;^-$ concentrations of the pore water were less than the overlying waters, while NH4+ and $SiO_2$ concentrations showed opposite trends. Exchangeable nutrients of sediment could be the repository for t]me nutrient exchange in the water-sediment interface.

• Clinical and Experimental Pediatrics
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• v.52 no.12
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• pp.1377-1382
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• 2009

Purpose:The gonadotropin-releasing hormone (GnRH) test results of girls with precocious puberty were analyzed to determine whether this test can efficiently and clearly differentiate between central precocious puberty (CPP) and other disorders. Methods:Clinical and laboratory data of 54 girls with precocious pubertal signs were reviewed. Intravenous GnRH test was performed with blood samples obtained at 0, 30, 60, and 90 minutes. A peak luteinizing hormone (LH) level of ${\geq}5.0IU/L$ was indicative of CPP. Results:Of the 40 girls with CPP, 36 (90.0%), 3 (7.5%), and 1 (2.5%) showed peak LH levels at 30, 60, and 90 minutes, respectively. A percentage of girls whose peak LH ${\geq}5.0IU/L$ up to 30, 60, and 90 minutes was 92.5%, 100%, and 100%, respectively. The peak LH/follicle stimulating hormone (FSH) ratio of girls with CPP was 0.89${\pm}$0.49 and was <1 in 16 of the 40 girls (40.0%). Girls with peak LH/FSH ratio of >1.0 showed higher chronological age (CA) ($8.3{\pm}0.6$ vs. $7.7{\pm}1.0$ years, P=0.033), bone age (BA) ($10.9{\pm}0.8$ vs. $9.7{\pm}1.1$ years, P=0.001), and BA-CA difference ($2.6{\pm}0.7$ vs. $2.0{\pm}0.7$ years, P=0.009) than those of girls with peak LH/FSH ratio of ${\leq}1.0$. Higher percentage of girls with peak LH/FSH ratio of >1.0 showed advanced breast development (${\geq}TannerIII$) (93.7% vs. 41.7%, P=0.001). Conclusion:LH levels after 30 and 60 minutes of intravenous GnRH administration are the most useful for diagnosing CPP in girls.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.35 no.2
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• pp.1-14
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• 2017

The purpose of this study is to understand the environmental traits and significance of the pond place that appears in historic maps in 'Dongchon(東村)', which is the eastern section within the fortress wall of Hanyang. We reviewed various documents and maps to identify the name of the pond, and of those materials we followed the name provided by official national records and geographical titles to designate it 'Eouidongji Pond(於義洞池).' The results of the research showed, first, that from the standpoint of location and environmental characteristics, that the area of the Eouidongji Pond was an area that contained a pastoral atmosphere within the city. It was located in an area where the waters flowing from the mountains gathered, and the boundaries of the pond would change based on water levels within a plot of land about 2,000pyeong(app. $6,600m^2$) in size. Second, when seen from the perspective of its creation background, the Eouidongji Pond seems to have been a naturally occurring pond which was modified when the water system was managed in the city at the beginning of the dynasty. In addition to its role as a reservoir, it was operated as a lotus pond(蓮池) to offer lotus(蓮) related by-products. With the nearby detached palace being actively used, it seems the pond was managed at the same time. The pond had already been filled in by the early 20th century, and although there were efforts to reconstruct the pond, it was eventually destroyed as the area was included in the site of a school during the colonial period. Third, the Eouidongji Pond was appreciated in many cases by individuals or admired as part of the natural landscape by viewing it from afar. In addition, it provided entry landscape near the road entering Dongchon, and was a location that was easily visited in connection with other nearby pleasure grounds. Through studying the location and environmental characteristics, the background of its creation and destruction, operation and management by time period, usage at the time, and characteristics of scenery appreciation of Eouidongji Pond, the Eouidongji Pond was a pond of high practical value to the nation, as it supplemented the water system in the city and was able to provide lotus harvests for the nation. In addition, from a urban environment perspective, it was a lateral landmark with a large area, as well as an effective boundary. It was an open area that the people of the Hanseong-bu could freely use, and it had a high public value due to its ease of accessibility.