• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.296-300
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• 2006

도시에 매설된 상수관망의 노후화와 매설된 주변 환경의 변화로 관 보수와 파괴가 자주 발생하게 된다. 이때 보수 또는 교체를 위하여 상수관망의 일부를 격리하여야 하며 이를 위해서 제수밸브를 차폐해야 한다. 그러나 제수밸브가 격리하고자 하는 영역 주변에 적절히 배치되어 있지 않은 경우 필요한 부분보다 많은 영역이 격리되게 되며, 이는 격리로 인한 피해범위를 증가시키게 된다. 이와 함께 적절치 못한 제수밸브 관리로 인해 제수밸브가 차폐되지 않는 경우 해당 제수밸브 주변에 위치한 제수밸브를 추가로 차폐해야 하는 경우가 발생하게 되며 추가적인 상수관의 격리로 인하여 처음의 상수관 격리에 의한 피해를 증가시키는 결과를 야기한다. 이러한 문제는 제수밸브의 효율적 배치로 감소할 수 있으나 효율적 배치를 위한 선행과제로 현재 설치되어 있는 제수밸브 배치의 적정성을 평가하는 것이 필요하다. 이를 위하여 본 연구에서는 상수관 격리와 제수밸브가 차폐되지 않는 경우를 동시에 고려한 모의방법(simulation)을 제안하였다. 상수관망 전체 대한 상수관 파괴당 평균적인 단수인구로 제수밸브의 적정 분포를 정량화하여 다양한 제수밸브 분포사이의 적정성을 비교할 수게 하였다. 이러한 비교를 바탕으로 새로운 상수관망에서 효율적인 제수밸브 분포가 가능하며 기존 상수관망에 제수밸브를 추가할 경우에도 유용한 결과를 얻을 수 있다.

• Journal of the Korean Geographical Society
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• v.43 no.4
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• pp.495-510
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• 2008

Vaccinium vitis-idaea or lingonberry, a typical arctic-alpine plant, is common on the circumpolar regions and alpine belts of the Northern Hemisphere, and also occurs on the alpine and subalpine belts of the Korean Peninsula, including Mt. Sorak and Hongchon. Vaccinium vitis-idaea at the elevation of c. 350m a.s.l. of Hongchon is found on the wind hole area with cool summer, and mild winter. Vaccinium vitis-idaea at Hongchon is regarded as the glacial relict of the Pleistocene period, and shows a disjunctive distribution, along with the alpine and subalpine belts of the northern and central Korea since the Holocene period. Present vertical range of Vaccinium vitis-idaea between Mt. Sorak and Hongchon might indicates that the temperatures during the glacial epoch was colder than today, down to -6 to $-7^{\circ}C$ Vaccinium vitis-idaea at this fragile wind hole site could be endanger if current global warming trends continues, and anthropogenic activities become serious.

• Journal of Forest and Environmental Science
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• v.11 no.1
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• pp.61-71
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• 1995

From Salix maximowiczii of the Korean Salix, morphological and palynological characters were investigated by stereoscopic, light, and scanning electron microscopes. Also, this study was eonducted to investigate the effect of meteorological factors on the disjunct distribution in Salix maximowiczii forests grown within the restricted region. 1. Morphological characters of S. maximowiczii clarified with the descriptions and figures. 2. The palynological description was made to the S. maximowiczii and identified distinctly species. 3. S. maximowiczii is distributed only in Baekdam and Hangyeryong valley of Mt. Sorak in Kangwon-do, and valley of height region in Kyeongseong-gun (Hamgyongbuk-do), Sinhueng-gun, and Pungsan-gun (Hamgyongnam-do) in North Korea. 4. Water factors was better than temperature factors in the influence of meteorological factors for disjunct distribution. 5. These ecological and taxonomical informations could be used in practical application for silvicultural prescription, such as erosion control forest, timber production, and development of green area in river bank.

• Journal of the Korea Society for Simulation
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• v.23 no.3
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• pp.27-32
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• 2014

In this paper, We are going to propose the novel structure with improved behavior than the conventional vertical structure for VLSI CMOS circuits. For this, the proposed structure is the moat shape for STI. We want to analysis the characteristics of simulations about the electron concentration distribution, oxide layer shape of hot electron stress, potential flux and electric field flux, electric field fo themal damage and current-voltage characteristics in devices. Physically based models are the ambient and stress bias conditions of TCAD tool. As a analysis results, shallow trench structure were trended to be electric functions of passive as device dimensions shrink. The electrical characteristics influence of proposed STI structures on the transistor applications become stronger the potential difference electric field and saturation threshold voltage, are decreased the stress effects of active region. The fabricated device of based on analysis results data were the almost same characteristics of simulation results data.

• Korean Journal of Plant Taxonomy
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• v.39 no.1
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• pp.35-41
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• 2009

Astilbe (Saxifragaceae) is a genus well known for its disjunctive distribution in Asia and eastern North America. In this study, we reconstructed a molecular phylogeny of the genus using the sequences of ITS regions of nuclear ribosomal DNA. A total of 17 species representing major lineage of Astilbe and closely related taxa were included in the phylogenetic analyses. We obtained a Bayesian phylogenetic tree in which Saxifragopsis was positioned as a sister group to Astilbe. The Japanese endemic species, A.platyphylla was the most basal lineage within the genus. This species is well known for its distinct morphological features such as unisexual flowers, apetaly, and calyx with 7-11 lobes. Two species, A. biternata, a New World representative of the genus, and A. rivularis widely distributed in S. Asia, branched off early in the evolution of Astilbe. The remaining species formed a strongly supported core clade, which diverged into two robust geographical lineages: the first ("Japonica" clade) of species distributed in Japan, Taiwan, and Philippines and the other ("Rubra" clade), of taxa in China and Korea. The ITS phylogeny indicates that the Bering land bridges were the major route for the origin and dispersal of A. biternata. The two Taiwanese taxa and A. philippinensis were found to derive from the Japanese member, as the genus advanced southwards. The ITS phylogeny suggests that apetaly originated independently at least two times within the genus. Our results do not support Engler's classification system of the genus based on the leaf type (simple vs. compound), but reaffirm Hara's taxonomic idea which primarily considered the features of calyx.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.341-345
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• 2017

In this study, the Inlet/Isolator model experiments performed at Texas University were performed by 2-dimensional RANS computerized analysis. First, supersonic flow conditions were analyzed and compared with experimental surface pressure results, and the flow structure was analyzed by confirming Mach number distribution and numerical shadowgraph. Then, the inlet unstart condition was given by changing the back pressure, and the URANS analysis was performed to confirm the progress of inlet unstart.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.31-36
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• 2015

As one of the most promising propulsive systems in the future, the dual-mode scramjet engine has drawn the attention of many researches. Detailed flow features concerned with the isolator play an important role in the dual-mode scramjet system. The 2D numerical method has been used for the dual-mode scramjet with wind tunnel. To validate the ability of the numerical model, numerical results have been compared with the experimental results. Overall pressure distributions show quite good match with the experimental results. Back pressure has been studied for maximum pressure rising. According to the results, pressure distribution of supersonic inlet section is not influenced by back pressure. The shock train is pushed towards upstream as the back pressure increases. The maximum value of back pressure without inlet unstart goes up rapidly and then keeps constant when the isolator length increases. The optimal length of isolator section ($L/H_{th}$) is 8.7 in this model.

• Journal of the Korean Geographical Society
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• v.37 no.4
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• pp.357-370
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• 2002

Present work aims to investigate the species composition, physiognomy and distribution of arctic-alpine and alpine plants(AAP) of the Korean Peninsula. The dominance of AAP in the northern Korea may be due to the frequent exchanges of floras with circumpolar regions for the seek of the glacial refugia during the alternate Pleistocene glacial epochs. The post-glacial climatic amelioration pushed AAP back northwards and upwards, so they now shows disjunctive distribution on separate mountain tops. The diverse morphological adaptations of AAP to severe environmental conditions, viz. the dominance of perennial species, stunted tree growth, multiple protection of leaves, krummholz, and dwarf shrubs, are the result of long-term graduall development which have safeguarded the survival of AAP in a such a harsh cryo-climatic area. The appearance of the Korean endemic AAP reflects the long-term isolation of species in Korea, and the local environmental diversities which have both accentuated this isolation and aided the development of genetic diversity. Evergreen broad-leaved AAP at c. 1,500m to 1,800m and above are now endangered because of the competition from down-slope plants, and from the global warming.

• The Korean Journal of Quaternary Research
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• v.5 no.1
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• pp.1-13
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• 1991

The distribution of cryophilous arctic-alpine and alpine plants in Korea is reviewed in connection with palaeoenvironment, along with a discussion to their origins, patterns of migration, and their refugia. At present, the estimated number of Korean arctic-alpine and alpine species is 419, and this includes 75 arctic-alpine species, 239 alpine species and 105 Korean endemic alpine species. The disjunctive distribution of cryophilous arctic-alpine and alpine plants is likely to be due to first, the downslope and southward expansion of those species towards the Korean peninsula as a primary refugia from the arctic region as the Pleistocene glacial phases approached, and then their subsequent isolation upslope in mountain areas toward a secondary refugia as the interglacial and post-glacial climatic ameliorations followed; secondly, the expansion of forest tree communities on lowland and montane areas subsequent to the end of the Pleistocene has had the effect of dividing formerly high mountains as a result of the increased competition; and thirdly, the general disapperance or restriction of available habitats for arctic-alpine and alpine species because of post-glacial climatic amelioration. The existence of 139 alpine species exclusively in the north of Korea may be due to the following reasons; first, frequent exchanges of alpine floras with other neighbouring East Asian regions would have been facilitated; secondly, there are numerous high mountains available for the alpine plants to survive and prosper during the post-glacial period; thirdly, the existence of easy accesses between mountains within the north, which has enabled alpine floras to migrate when necessary; and finally, the availability of diverse environments and habitats for the alpine flora of the north. However, the continued survival of those species in Korea at the world's or East Asia's southernmost limits of their distribution for many species is in danger if global warming associated with the greenhouse effect takes place.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2509-2515
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• 2014

In this paper, the conventional vertical structure for VLSI circuits CMOS intend to improve the stress effects of active region and built-in threshold voltage. For these improvement, the proposed structure is shallow trench isolation of moat shape. We want to analysis the electron concentration distribution, gate bias vs energy band, thermal stress and dielectric enhanced field of thermal damage between vertical structure and proposed moat shape. Physically based models are the ambient and stress bias conditions of TCAD tool. As an analysis results, shallow trench structure were intended to be electric functions of passive as device dimensions shrink, the electrical characteristics influence of proposed STI structures on the transistor applications become stronger the potential difference electric field and saturation threshold voltage, are decreased the stress effects of active region. The fabricated device of based on analysis results data were the almost same characteristics of simulation results data.