• Management & Information Systems Review
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• v.37 no.1
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• pp.155-175
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• 2018

Lots of previous researches on determinants of apartment prices in Korea consider spatial dependence while few studies regard endogeneity of spatial lag by adding a spatial lag to an OLS regression. Thus, this study intends to include this spatial lag in its analysis of determinants of apartment price in Busan by using a two-stage quantile regression. The empirical results are : the coefficient of spatial lag variable is more than 0.5 and is statistically significant at 1% level. From this result we can confirm that the effect of the price of nearby apartment on that of another apartment is very big. We also find that apartment buyers prefer larger size, height in both the total floors and living floor, south-facing living room with a ocean view, and proximity to metros, high school and coast. Unlike our expectation, however, mountain view is less favored than building view, which we can guess is because apartments with mountain views are mostly located in the low-priced apartment area where some of their living rooms face north. Quantile regression also explains the effect of hedonic characteristics on apartment price better than OLS estimation. For instance, the effect of south facing living room variable on the price is twice larger in high-price apartments than in low-price counterparts. And the effect of vicinity to the coast or the ocean is ten times bigger in high priced apartments.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.1
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• pp.114-126
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• 2016

Many cohort studies have reported associations of individual-level long-term exposures to $PM_{10}$ and health outcomes. Individual exposures were often estimated by using exposure prediction models relying on $PM_{10}$ data measured at national regulatory monitoring sites. This study explored spatial and temporal characteristics of regulatory $PM_{10}$ measurement data in South Korea and suggested $PM_{10}$ concentration metrics as long-term exposures for assessing health effects in cohort studies. We obtained hourly $PM_{10}$ data from the National Institute of Environmental Research for 2001~2012 in South Korea. We investigated spatial distribution of monitoring sites using the density and proximity in each of the 16 metropolitan cities and provinces. The temporal characteristics of $PM_{10}$ measurement data were examined by annual/seasonal/diurnal patterns across urban background monitoring sites after excluding Asian dust days. For spatial characteristics of $PM_{10}$ measurement data, we computed coefficient of variation (CV) and coefficient of divergence (COD). Based on temporal and spatial investigation, we suggested preferred long-term metrics for cohort studies. In 2010, 294 urban background monitoring sites were located in South Korea with a site over an area of $415.0km^2$ and distant from another site by 31.0 km on average. Annual average $PM_{10}$ concentrations decreased by 19.8% from 2001 to 2012, and seasonal $PM_{10}$ patterns were consistent over study years with higher concentrations in spring and winter. Spatial variability was relatively small with 6~19% of CV and 21~46% of COD across 16 metropolitan cities and provinces in 2010. To maximize spatial coverage and reflect temporal and spatial distributions, our suggestion for $PM_{10}$ metrics representing long-term exposures was the average for one or multiple years after 2009. This study provides the knowledge of all available $PM_{10}$ data measured at national regulatory monitoring sites in South Korea and the insight of the plausible longterm exposure metric for cohort studies.

• Korean Journal of Remote Sensing
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• v.27 no.6
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• pp.717-728
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• 2011

An efficient method for the unsupervised classification of high resolution imagery is suggested in this paper. It employs pixel-linking and merging based on the adjacency graph. The proposed algorithm uses the neighbor lines of 8 directions to include information in spatial proximity. Two approaches are suggested to employ neighbor lines in the linking. One is to compute the dissimilarity measure for the pixel-linking using information from the best lines with the smallest non. The other is to select the best directions for the dissimilarity measure by comparing the non-homogeneity of each line in the same direction of two adjacent pixels. The resultant partition of pixel-linking is segmented and classified by the merging based on the regional and spectral adjacency graphs. This study performed extensive experiments using simulation data and a real high resolution data of IKONOS. The experimental results show that the new approach proposed in this study is quite effective to provide segments of high quality for object-based analysis and proper land-cover map for high resolution imagery of urban area.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.245-245
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• 2005

This paper addresses the use of directional textural information for connecting road segments. In urban scene, some roads are occluded by buildings, casting shadow of buildings, trees, and cars on streets. Automatic extraction of road network from remotely sensed high resolution imagery is generally hindered by them. The results of automatic road network extraction will be incomplete. To overcome this problem, several perceptual grouping algorithms are often used based on similarity, proximity, continuation, and symmetry. Roads have directions and are connected to adjacent roads with certain angles. The directional information is used to guide road fragments connection based on roads directional inertia or characteristics of road junctions. In the primitive stage, roads are extracted with textural and direction information automatically with certain length of linearity. The primitive road fragments are connected based on the directional information to improve the road network. Experimental results show some contribution of this approach for completing road network, specifically in urban area.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3229-3232
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• 2011

A FRET-based high-throughput screening system was developed for the discovery of competitive smallmolecule Hsp90 inhibitors. The biarsenical fluorescein derivative FlAsH and dabcyl-conjugated Hsp90 inhibitor GM were employed as the FRET donor and quencher, respectively. The spatial proximity perturbation between FlAsH-labeled Hsp90N and GM-dabcyl upon treatment of a small molecule led to changes in the FRET-induced fluorescence, monitored in a high-throughput fashion.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2009.04a
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• pp.3-5
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• 2009

The matching process is not simple, since the identified features from different sources do not always match in their location, extent, and description. We present a new approach to matching GIS features from disparate sources. A graph theoretic approach is used to model the geographic context and to determine the matching features from multiple sources.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.118-120
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• 2003

이동체 데이터베이스에서 이동체 궤적의 양은 엄청나게 많아서 기존의 단일 디스크 기반에서는 특정영역의 질의에 대한 빠른 응답과 처리율의 향상을 볼수 없다. 따라서 고성능 질의 처리를 위한 시스템의 성능 향상을 위해서는 병렬 처리 기법의 도입이 필요하다. 이런 병렬 처리 기법 중, 기존의 디클러스터링 방법에서는 시간이 지남에 따라 연속적으로 보고되는 이동체 특성을 고려하지 않고 있다. 그러므로 대용량 이동체 데이터에 대하여 고성능 질의 처리를 위한 새로운 디클러스터링 방법이 필요하다. 이 논문에서는 대용량 이동체 데이터베이스에 대한 고성능 질의 처리를 위한 새로운 디클러스터링 정책을 제시하였다. 이동체 데이터의 MBB중 공간 좌표의 근접성만을 고려하여 하나의 SemiAllocation Disk 값을 설정하고 그 값과 시간 도메인을 다시 고려하여 근접성을 계산함으로써 디클러스터링을 할 수 있다. 또한 디스크별 Load Balancing을 고려하여 보다 정확한 디클러스터링 효과를 가지도록 하였다. 이와 같이 이동체의 특성을 고려한 새로운 디클러스터링 정책으로 시스템의 성능을 향상 시킬 수 있다.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.854-859
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• 2002

Location Based Services, or LBS refers to value-added service by processing information utilizing mobile user location. With the rapidly increasing wireless internet subscribers and world LBS market, the various location based applications are introduced such as buddy finder, proximity and security services. As the killer application of the wireless internet, the LBS has preconsidered technology about location determination technology, LBS middleware server for various application, and diverse contents processing technology. This paper describes the open architecture for LBS platform ensuring interoperability among the wireless networks and various location-based application services and the functional requirements for the LBS platform. The LBS platform in a narrow sense provides a standard interfaces for location management and network management for location services as follows, positioning (location acquisition through network or/and handset), location managing, location based functions, profile management, authentication and security, location based billing, information roaming between carriers and the system monitoring independent to specific network or ISP/CPs(Content Providers).

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.218-220
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• 2012

최근 클라우드 컴퓨팅이 발전함에 따라 공간 데이터베이스의 아웃소싱(outsourcing)에 대한 관심이 급증하고 있다. 따라서 데이터베이스 아웃소싱에서의 위치 데이터 보호를 위한 공간 좌표 변환 기법이 활발히 연구되어 왔다. 그러나 기존 공간 좌표 변환 기법들은 근접(proximity) 공격에 취약하기 때문에, 데이터 베이스 아웃소싱을 통해 서비스를 제공받는 사용자의 프라이버시를 보호하지 못한다는 문제점이 존재한다. 따라서 사용자의 안전하고 편리한 서비스 사용을 위한 공간 좌표 변환 기법이 요구된다. 이를 위해, 본 논문에서는 선대칭 이동 기반 공간 좌표 변환 기법을 제안한다. 제안하는 기법은 위치 데이터 보호를 위해 데이터 분포 변환 및 에러 삽입을 수행하고 근접 공격의 효율적인 방지를 위해 선대칭 이동을 이용한 공간 좌표 변환을 수행한다. 또한, 성능평가를 통해 제안하는 기법이 근접 공격에의 노출 확률을 크게 감소시키면서, 빠르게 공간 좌표 변환을 수행함을 검증한다.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.3012-3017
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• 2021

The spatial distribution and the energy spectrum of the neutron yield were investigated with the neutron activation analysis and MCNP simulation was carried out to verify the analysis results and to extend the results to a 3D mapping of the neutron yield distribution in the KSTAR. High purity Ni specimen was selected in the neutron activation analysis. Total neutron yields turned out to be 3.76 × 10¹² n/s - 7.56 × 10¹² n/s at the outer vessel of the KSTAR, two orders of magnitude lower than those at the inner vessel of the KSTAR, which demonstrates the attenuation of neutron yield while passing through the different structural materials of the reactor. Based on the fully expanded 3D simulation results, 2D cross-sectional distributions of the neutron yield on XY and ZX planes of KSTAR were examined. The results reveal that the neutron yield has its maximum concentration near the center of blanket and decreases with increasing proximity to the vacuum vessel wall.