• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.4
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• pp.175-182
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• 2000

Spatial interpolation of daily temperature forecasts and observations issued by public weather services is frequently required to make them applicable to agricultural activities and modeling tasks. In contrast to the long term averages like monthly normals, terrain effects are not considered in most spatial interpolations for short term temperatures. This may cause erroneous results in mountainous regions where the observation network hardly covers full features of the complicated terrain. We developed a spatial interpolation model for daily minimum temperature which combines inverse distance squared weighting and elevation difference correction. This model uses a time dependent function for 'mountain slope lapse rate', which can be derived from regression analyses of the station observations with respect to the geographical and topographical features of the surroundings including the station elevation. We applied this model to interpolation of daily minimum temperature over the mountainous Korean Peninsula using 63 standard weather station data. For the first step, a primitive temperature surface was interpolated by inverse distance squared weighting of the 63 point data. Next, a virtual elevation surface was reconstructed by spatially interpolating the 63 station elevation data and subtracted from the elevation surface of a digital elevation model with 1 km grid spacing to obtain the elevation difference at each grid cell. Final estimates of daily minimum temperature at all the grid cells were obtained by applying the calculated daily lapse rate to the elevation difference and adjusting the inverse distance weighted estimates. Independent, measured data sets from 267 automated weather station locations were used to calculate the estimation errors on 12 dates, randomly selected one for each month in 1999. Analysis of 3 terms of estimation errors (mean error, mean absolute error, and root mean squared error) indicates a substantial improvement over the inverse distance squared weighting.

• Proceedings of the KGS Conference
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• 2003.11a
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• pp.144-148
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• 2003

1) 연구의 배경와 목적 정보통신기술의 비약적 발전은 공간이동에 있어서 '거리' 개념의 근본적인 변화를 가져오고 있다. 흔히 '시간에 의한 공간소멸' 또는 '시공간 압축'이라고 표현되는 그와 같은 변화는 일상적 생활공간에서뿐만 아니라 전지구적 범위에 이르기까지 장소와 장소, 지역과 지역 간에 발생하는 정보의 흐름을 실시간(real time)으로 연결한다. 그러나 정보통신기술의 발달이 장소와 장소, 지역과 지역 간에 발생하는 모든 통행을 대체하지는 못한다. (중략)

• The Mathematical Education
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• v.13 no.3
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• pp.17-18
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• 1975

거리공간과 Normal countable compact의 위상적이 Normal이라는 것은 A.H. Stone에 의하여 이미 밝혀졌고, V.I. Malyhin은 space expX의 Cardrmal invariant와 공간 X 사이의 관계를 논하였다. 본 논문에서는 V.I. Malyin이 밝힌 tightness의 개념을 도입하여 countable tightness의 pracompact와 normal strongly countable compact 공간의 topological product가 Normal이라는 것을 증명하였다.

• Journal of Korea Multimedia Society
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• v.15 no.2
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• pp.215-225
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• 2012

In multimedia database, a multidimensional space-based indexing has been used to increase search efficiency. However, this method is inefficient in terms of ubiquity because it uses Euclidean distance as a scale of distance calculation. On the contrary, a metric space-based indexing method, in which metric axiom is prerequisite is widely available because a metric scale other than Euclidean distance could be used. This paper is attempted to propose a way of improving VP-tree, one of the metric space indexing methods. The VP-tree calculates the distance with an object which is ultimately linked to the a leaf node depending on the node fit for the search range from a root node and examines if it is appropriate with the search range. Because search speed decreases as the number of distance calculations at the leaf node increases, however, this paper has proposed a method which uses the latest interface on query object as the base point of trigonometric inequality for improvement after focusing on the trigonometric inequality-based range compression method in a leaf node. This improvement method would be able to narrow the search range and reduce the number of distance calculations. According to a system performance test using 10,000 video data, the new method reduced search time for similar videos by 5-12%, compared to a conventional method.

• Journal of the Korean association of regional geographers
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• v.10 no.2
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• pp.356-370
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• 2004

New communication and information technologies such as the Internet are space-adjusting technologies. The Internet changes the spatial proximity by improving the connections between people and organizations separated by geographical distance This paper examines the digital position of individual nation-states on a global cyberspace. The number of inter-domain hyperlinks embedded in websites for 47 nations was gathered using the AltaVista in 2001 Data were also obtained on the geographical distance among the nations. The results indicate that the u.s. is the most central nation on the global cyberspace, followed by the U.K., Germany, Australia, Canada, Italy, France, China and Japan. The most peripheral nations are Uruguay, Luxemburg, and UAE. It also examines the relationship between the digital positions of 47 nations and their physical locations. The results indicate that digital structure on the cyberspace is not significantly related to geographical distance among those nations.

• Journal of Life Science
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• v.20 no.9
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• pp.1287-1293
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• 2010

The spatial distribution of alleles and geographical distances of a Carex humilis population on Mt. Giri in Korea were studied. A total of 102 DNA fragments (bands) were found among 107 plants. Among these 102 bands, 48 (47.1%) bands were polymorphic. In a simple variability of subpopulations by the percentage of polymorphic bands, distances I and V exhibited the lowest variation (16.7%). Distance VIII showed the highest variation (22.6%). The total genetic diversity (H) was 0.076 across species. Class VIII had the highest H (0.093), while class I had the lowest (0.063). Genetic similarity of individuals was found among subpopulations at up to a scale of 60 m distance, and this was partly due to a combination of alleles. Within the Mt. Giri population, a strong spatial structure was observed for RAPD markers, indicating a very low amount of migration among subpopulations and that the distribution of individual genotypes of a given population was clumped. The present study demonstrated that analysis of RAPD markers could be successfully used to study the spatial and genetic structures of C. humilis.

• Journal of Korean Society of Forest Science
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• v.101 no.2
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• pp.203-212
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• 2012

This study aims to test presence of spatial autocorrelation of burn severity in Uljin and Youngduk areas burned in 2011. SPOT satellite images were used to compute the NDVI representing burn severity, and NDVI values were sampled for 5,000 randomly dispersed points for each site. Spatial autocorrelations of sampled NDVI values were analyzed with Moran's I and Variogram models. Moran's I values of burn severity in Uljin and Youngduk areas were 0.7745 and 0.7968, respectively, indicating presence of strong spatial autocorrelations. On the basis of Variogram and changes of Moran's I values by lag class, ideal sampling distance were proposed, which were 566-2,151 m for Uljin and 272-402 m for Youngduk. It was recommended to apply these ranges of sampling distance in flexible corresponding to Anisotropic characteristics of burned areas.

• Spatial Information Research
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• v.20 no.3
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• pp.67-81
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• 2012

Due to the recent advancement of cloud computing, the research on database outsourcing has been actively done. Moreover, the number of users who utilize Location-based Services(LBS) has been increasing with the development in w ireless communication technology and mobile devices. Therefore, LBS providers attempt to outsource their spatial database to service provider, in order to reduce costs for data storage and management. However, because unauthorized access to sensitive data is possible in spatial database outsourcing, it is necessary to study on the preservation of a user's privacy. Thus, we, in this paper, propose a spatial data encryption scheme to produce outsourced database from an original database. We also propose a k-Nearest Neighbor(k-NN) query processing algorithm that efficiently performs k-NN by using the outsourced database. Finally, we show from performance analysis that our algorithm outperforms the existing one.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.5
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• pp.69-78
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• 2005

It is crucial to compute the Euclidean distance between two vectors efficiently in high dimensional space for multimedia information retrieval. In this paper, we propose an effective method for approximating the Euclidean distance between two high-dimensional vectors. For this approximation, a previous method, which simply employs norms of two vectors, has been proposed. This method, however, ignores the angle between two vectors in approximation, and thus suffers from large approximation errors. Our method introduces an additional vector called a reference vector for estimating the angle between the two vectors, and approximates the Euclidean distance accurately by using the estimated angle. This makes the approximation errors reduced significantly compared with the previous method. Also, we formally prove that the value approximated by our method is always smaller than the actual Euclidean distance. This implies that our method does not incur any false dismissal in multimedia information retrieval. Finally, we verify the superiority of the proposed method via performance evaluation with extensive experiments.

• Korean Journal of Materials Research
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• v.4 no.3
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• pp.253-258
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• 1994

The effect of hole size and hole-to-hole distance in the braided and laminated composite was studied in terms of tensile strength, pin bearing strength, and flexural strength of S2-glass fiber braided polyester. The tensile strength reduction with hole size was well fitted with he Whitney and Nuismer's prediction for the laminated composite. The characteristic distance was measured to be about 1.6mm for braided composite and 1.8mm for laminated one. The effect of distance between the centers of two circu lar holes on tensile strength was negligible when the distance between these two holes was larger than 4 times of the diameter of circular hole for both braided and laminated composite. The side effect was diminished when the center of hole was located 3 times farther than the diamet.er of the hole. The pin bearing strengths was decreased with the size of pin hole for both braided and laminated composite.