• Journal of Astronomy and Space Sciences
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• v.10 no.2
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• pp.163-188
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• 1993

On the framework of Tolman spacetime model, the caustics around a local perturbed region in redshift is due to the local expansion rate induced by a local density inhomogeneity in real space. We have compared the caustics in redshift space, which are analytically obtained, with the observed redshift-distance patterns of galaxies which are belonging to Coma and Perseus clusters. For the Abell density distribution model and polytropic density profiles which are well-fitting the optical and X-ray observations, respectively, the size of caustics which is defined by "turnaround radius" of a local density perturbed region should give constraints on the sizes and masses of rich clusters and give also a clue to understand the state of hot X-ray emitting gas.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2004.05a
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• pp.91-91
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• 2004

• Journal of the Korean Chemical Society
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• v.23 no.1
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• pp.15-19
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• 1979

The new concept of the Bonding and Antibonding Regions in the transition density space is developed from the Integral Hellmann-Feynman Theorem and the positive definiteness of the transition density. The unility of this concept is fully demonstrated for H2 system. It is expected that the nature of the electronic perturbation energy due to the change of nuclear configuration can be successfully understood by using this concept. Properties of the transition density is briefly discussed.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.124-126
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• 2003

다차원 색인 기법 M-트리는 노드의 중심점과 객체간의 상대적 거리로 색인을 구성하고, 검색 공간에 포함되는 객체를 액세스하는 기법으로서 노드들은 페이지 단위로 구성되며 하위 엔트리들을 포함할 수 있는 반경, 즉 유사도 거리에 의해 노드의 영역이 표현되어진다. 그러나 이와 같은 노드의 영역 표현에 있어서 노드 색인공간의 중첩으로 인해 질의 시 검색 패스가 증가하고 이로 인해 거리계산과 디스크 입출력의 증가를 야기하는 문제를 갖는다. 본 논문에서는 M-트리에서 문제가 되고 있는 노드 색인 공간의 중첩을 최소화할 수 있는 노드 분할 정책을 제안한다. 기존의 M-트리와는 다르게 노드의 가상 중심점을 계산하여 그것을 라우팅 객체로 만들어 노드를 커버하는 영역을 최소화하고 노드 안의 엔트리를 재분배하여 밀도 높은 노드를 구성 하도록 한다. 제안된 분할 알고리즘의 효율성을 증명하기 위한 실험 결과 색인공간의 중첩이 줄고 이로 인해 거리계산과 디스크 입출력의 횟수가 줄어듦을 보였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.2
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• pp.225-236
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• 2014

Shear wave velocity was used to estimate the geotechnical characteristics (void ratio and shear strength) of ground near an underground rainfall storage facility. An oedometer cell was utilized to measure the shear wave velocity and the displacement of specimens. Shear strengths were obtained by direct shear tests. The relationships along the shear wave velocity, void ratio, and shear strength were verified and used to infer the shear strength profile with the depth. In addition, changes in shear strength due to the construction of the underground rainfall storage system were estimated using the suggested method. The results show that the in-situ shear strength deduced from the shear wave velocity-void ratio-shear strength relationship is in good agreement with that obtained from an in-situ investigation (SPT).

• Spatial Information Research
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• v.22 no.6
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• pp.81-90
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• 2014

This study analyzed an impact relationship between the variable of street based on the walking enhancement factors and the street revitalization. In detail, walking enhancement factors include a physical environment, accessibility and a density which was derived from previous studies. In addition, This study also analyzed the diversity of the profession which was emphasized by Jacobs(1961) and the influence of the specific space on street revitalization that was emphasized by Ray Oldenburg (1989) and Richard MacCormac (1983). The anlaysis by types showed the walking enhancement factors, including street envirnoment, accessibility, density and diversity, which were emphasized by Jacobs(1961) possessed similararites between weekdays and weekends. On contrast, the spatial distribution of stores showed a major difference of influences on street revitalization between weekdays and weekends as Ray Oldenburg (1989) and Richard MacComac (1983) has insisted.

• Korean Journal of Environment and Ecology
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• v.25 no.4
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• pp.516-525
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• 2011

We studied the influence certain environmental factors (proximity of roosting site, roads, and residential areas) have on the spatial distribution of cranes in the Cheorwon, Korea. Using a range finder and GPS, data were collected from January to February 2007 and were subsequently evaluated with ArcGIS. The size of the cranes' wintering habitat was estimated to be 7$76.9km^2$. Five hundred and fifty-five flocks of cranes were observed and detailed distributions were collected. Feeding distribution of the cranes showed clustered distribution, however, no tendencies of spatial autocorrelation were apparent. Adjacent regions with paved roads and residences showed lower densities than other areas. Distances at which paved roads and residential areas induced changes in feeding flock densities were 1500m and 1750m, respectively. Feeding flock density decreased with increased distance from roosting site. Feeding flock density of the two crane species did not increase as distance from roads increased, however, the density of individuals showed a significant increasing tendency with increased distance from roads. In both species, density of feeding flocks and individuals significantly increased with increasing distance from residential areas. In Red-crowned Cranes, the density of feeding flocks and individuals significantly decreased with increasing distance from roosting site, however, in the case of White-naped Cranes, there was an even distribution in density of feeding flocks and individuals.

• Journal of Environmental Impact Assessment
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• v.28 no.6
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• pp.580-591
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• 2019

This study analyzed roadkill hotspots in Yeongju, Mungyeong-si Andong-si and Cheongsong-gun to compare the method of searching the area of the spatial cluster for selecting the roadkill hotspots. The local spatial autocorrelation index Getis-Ord Gi* statistics were calculated by different units of analysis, drawing hotspot areas of 9% from 300 m and 14% from 1 km on the basis of the total road area. The rating of Z-score in the 1km hotspot area showed the highest Z-score in the 28th National Road section on the border between Yecheon-gun and Yeongj-si. The kernel density method performed general kernel density estimation and network kernel density estimation analysis, both of which made it easier to visualize roadkill hotspots than district unit analysis, but there were limitations that it was difficult to determine statistically significant priority. As a result, local hotspot areas were found to be different according to the cluster analysis method, and areas that are in common need of reduction measures were found to be the hotspot of 28th National Road through Yeongju-si and Yecheon-gun. It is deemed that the results of this study can be used as basic data when identifying roadkill hotspots and establishing measures to reduce roadkill.

• Journal of Korea Water Resources Association
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• v.35 no.1
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• pp.1-12
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• 2002

This study was intended to investigate the rainfall-runoff relationship with spatially distributed rainfall data, and then, to analyze and quantify the uncertainty induced by spatially averaging rainfall data. For constructing spatially distributed rainfall data, several historical rainfall events were extended spatially by simple kriging method based on the semivariogram as a function of the relative distance. Runoff was computed by two models; one was the modified Clark model with spatially distributed rainfall data and the other was the conventional Clark model with spatially averaged rainfall data. Rainfall errors and discharge errors occurred through this process were defined and analyzed with respect to various rain-gage network densities. The following conclusions were derived as the results of this work; 1) The conventional Clark parameters could be appropriate for translating spatially distributed rainfall data. 2) The parameters estimated by the modified Clark model are more stable than those of the conventional Clark model. 3) Rainfall and discharge errors are shown to be reduced exponentially as the density of rain-gage network is increased. 4) It was found that discharge errors were affected largely by rainfall errors as the rain-gage network density was small.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.147.2-147.2
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• 2012

보현산 천문대 1.8m 망원경과 2K CCD를 이용하여 늙은 산개성단 NGC 2420에 대해 V ~ 22까지 VI측광 관측을 수행하였다. Chi^2 최소화를 이용한 정밀한 이론적인 등연령 곡선 맞추기 방법으로 성단의 기본 물리량을 구하고, 색-등급도(CMD)와 공간상에서의 별들의 위치를 이용하여 별들의 통계적인 구성원 확률을 결정하고자 한다. 한편 쌍성의 공간상의 분포를 조사하여 역학적 진화에 따른 쌍성의 분포특징을 살펴보고, 2차원 표면개수 밀도 분포로부터 성단의 형태를 조사하여 우리 은하면과의 상관관계에 대해 논의하고자 한다.