• 한국지역지리학회지
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• 제10권2호
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• pp.356-370
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• 2004

인터넷의 확산과 함께 글로벌 커뮤니케이션을 가로막았던 경제적, 지리적 장벽은 정차 제거되고 있는 상황에서 인터넷을 이용한 국가간 정보교환에 대한 연구, 그리고 정보교환과 지리적 거리와의 상관성 등에 대한 연구는 충분히 이루어 지지 않은 형편이다. 본 연의 목적은 인터넷 상에서 각 국가가 지닌 사이버상의 디지털 위치에 대한 현황과 함께, 이것이 국가간 지리적 경계와 어떤 연관성이 있는가를 검토하는 것이다. 연구 결과에 따르면, 미국이 사이버 공간에서 가장 중심적인(central) 위치를 차지하는 것으로 나타났다. 다음으로 영국, 독일, 호주, 이태리, 프랑스, 캐나다, 일본, 중국이 준중심적인(semi-central) 국가들이었다. 주변적인(peripheral) 국가들은 우루과이, 룩셈부르그, 아람에밀레이트 등으로 나타났다. 둘째로 사이버 공간의 국가별 디지털 위치와 지리적 거리는 통계적으로 유의미한(significant) 상환관계를 보이지 않았다.

• 한국농공학회논문집
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• 제60권3호
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• pp.135-148
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• 2018

Reservoir sedimentation is a major environmental issue, and various sediment load controls and plans have been proposed to secure clean and safe water resources. The objectives of this study were to estimate soil loss in the upper basins and predict sediment deposition in Ipjang reservoir using hydrologic and hydraulic model. To do so, SWAT (Soil and Water Assessment Tool) and EFDC (Environmental Fluid Dynamics Code) was used to estimate soil loss in two upper basins and to predict spatial distribution and amount of sediment deposition in the Ipjang reservoir, respectively. The hydrologic modeling results showed that annual average soil loss from the upper basins was 500 ton. The hydraulic modeling results demonstrated that sediment particles transported to the reservoir were mostly trapped in the vicinity of the reservoir inlet and then moved toward the bank over time. If long-term water quality monitoring and sediment survey are performed, this study can be used as a tool for predicting the dredging amount, dredging location and proper dredging cycle in the reservoir. The study findings are expected to be used as a basis to establish management solutions for sediment reduction.

• Journal of Astronomy and Space Sciences
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• 제33권1호
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• pp.29-36
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• 2016

The East African ionosphere (3°S-18°N, 32°E-50°E) was mapped using Total Electron Content (TEC) measurements from ground-based GPS receivers situated at Asmara, Mekelle, Bahir Dar, Robe, Arbaminch, and Nairobi. Assuming a thin shell ionosphere at 350 km altitude, we project the Ionospheric Pierce Point (IPP) of a slant TEC measurement with an elevation angle of >10° to its corresponding location on the map. We then infer the estimated values at any point of interest from the vertical TEC values at the projected locations by means of interpolation. The total number of projected IPPs is in the range of 24-66 at any one time. Since the distribution of the projected IPPs is irregularly spaced, we have used an inverse distance weighted interpolation method to obtain a spatial grid resolution of 1°×1° latitude and longitude, respectively. The TEC maps were generated for the year 2008, with a 2 hr temporal resolution. We note that TEC varies diurnally, with a peak in the late afternoon (at 1700 LT), due to the equatorial ionospheric anomaly. We have observed higher TEC values at low latitudes in both hemispheres compared to the magnetic equatorial region, capturing the ionospheric distribution of the equatorial anomaly. We have also confirmed the equatorial seasonal variation in the ionosphere, characterized by minimum TEC values during the solstices and maximum values during the equinoxes. We evaluate the reliability of the map, demonstrating a mean error (difference between the measured and interpolated values) range of 0.04-0.2 TECU (Total Electron Content Unit). As more measured TEC values become available in this region, the TEC map will be more reliable, thereby allowing us to study in detail the equatorial ionosphere of the African sector, where ionospheric measurements are currently very few.

• Journal of Computing Science and Engineering
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• 제5권3호
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• pp.210-222
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• 2011

In this work, we study the problem of privacy-preservation data publishing in moving objects databases. In particular, the trajectory of a mobile user in a plane is no longer a polyline in a two-dimensional space, instead it is a two-dimensional surface of fixed width $2A_{min}$, where $A_{min}$ defines the semi-diameter of the minimum spatial circular extent that must replace the real location of the mobile user on the XY-plane, in the anonymized (kNN) request. The desired anonymity is not achieved and the entire system becomes vulnerable to attackers, since a malicious attacker can observe that during the time, many of the neighbors' ids change, except for a small number of users. Thus, we reinforce the privacy model by clustering the mobile users according to their motion patterns in (u, ${\theta}$) plane, where u and ${\theta}$ define the velocity measure and the motion direction (angle) respectively. In this case, the anonymized (kNN) request looks up neighbors, who belong to the same cluster with the mobile requester in (u, ${\theta}$) space: Thus, we know that the trajectory of the k-anonymous mobile user is within this surface, but we do not know exactly where. We transform the surface's boundary poly-lines to dual points and we focus on the information distortion introduced by this space translation. We develop a set of efficient spatiotemporal access methods and we experimentally measure the impact of information distortion by comparing the performance results of the same spatiotemporal range queries executed on the original database and on the anonymized one.

• 정보관리학회지
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• 제37권2호
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• pp.71-93
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• 2020

오늘날 다양한 질병의 출현과 빠르게 변화하는 의료환경에 보다 효과적으로 대처하기 위해 대학병원 내에서 여러 진료과들이 협업진료를 수행하고 있다. 이러한 협업진료는 매우 중요하며 의료 현장에서 이미 보편화되어 있다. 그럼에도 불구하고, 이에 대한 연구, 특히 진료과들이 어떻게 협업을 하고 있는지에 대한 연구는 전무하다. 따라서 본 연구는 대학병원 내의 진료과 간의 협업진료 관계를 탐색하여 진료협업 네트워크 특성들이 연도별 및 계절별로 어떻게 달라지는지를 고찰하는 것에 목적이 있다. 본 연구는 국내 A대학교 대학병원에서 이루어진 29개 진료과 사이의 협업 진료를 연도별 및 계절별로 나누어 29개 진료과 협업 네트워크를 분석하였다. 협업진료의 요청 및 피요청에 따라 방향네트워크를 구성하였으며, 매개중심성, 아이겐벡터중심성, 근접중심성 분석, 에고 네트워크 분석 및 팩션분석과 더불어 추후 인터뷰도 실시하였다. 본 연구는 최초의 진료과 간의 협업 네트워크 분석을 수행하였으며, 의료기관 내에서의 동선을 고려한 진료과의 위치 및 공간 구성에 새로운 통찰력을 제시할 것으로 기대된다.

• 한국멀티미디어학회논문지
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• 제10권7호
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• pp.856-868
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• 2007

본 논문에서는 블록의 속성과 질감특징을 이용하여 효과적인 블록 분류 방법을 제안하였다. 제안한 방법에서는 먼저 명암도 문서영상을 이진화한 후, 평활화 기법을 적용하여 블록의 위치정보와 본 논문에서 사용할 특징 중에 하나인 각 블록의 내부에 있는 작은 블록들의 최대 높이 값을 구하였다. 이 위치정보들을 이용하여 문서영상을 각 블록으로 분할한다. 이 블록의 명암도 블록영상에서 문서의 속성이 잘 반영된 (0,1) 방향의 공간 명암도 의존 행렬을 구하여 7가지 질감특징을 구하였다. 먼저 블록의 속성을 최소거리 규칙(Nearest Neighbor Rule)에 입력하여 문자와 비문자 영역으로, 상세분류를 위하여 7가지 질감특징을 이용하여 큰 문자, 작은 문자, 표, 그래픽 및 사진 등으로 구분함으로써 문서인식을 위한 구조 해석뿐만 아니라 다양한 응용 분야에 효과적으로 이용될 수 있도록 하였다.

• 농촌계획
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• 제23권2호
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• pp.55-65
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• 2017

This study is to estimate the circuity factors which can be used to assess for public facilities accessibility and analyze traffic in the area. We set the range of the administrative districts by Si Gun Gu unit and Eup Myeon Dong unit (more subdivided unit than Si Gun Gu unit). The average circuity factor in Si Gun Gu unit is 1.364 (maximum 2.953 and minimum 1.711). The region indicated the highest value of circuity factor is wando-gun in jeollanam-do, which area consists of 4 island and is connected to the bridges. Having to use the bridges for using public facilities hinders its accessibility. In the case of Eup Myeon Dong unit, the average circuity factor is 1.353 (maximum 2.950 and minimum 1.154). The region indicated the highest value of circuity factor is buksan-myeon in chuncheon-si, Gangwon-do. This region also has to use bridges for using public facilities because there is the largest lake, called Soyangho. This circuity factor is used to analyze the location of public facilities and assess vulnerability of accessibility. And also the factor can be applied to some policies, such as rural public service planning based on spatial big data.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.471-474
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• 2006

Several planktonic dinoflagellates, including Cochlodinium polykrikoides (p), are known to produce red tides responsible for massive fish kills and serious economic loss in turbid Northwest Pacific (Korean and neighboring) coastal waters during summer and fall seasons. In order to mitigate the impacts of these red tides, it is therefore very essential to detect, monitor and forecast their development and movement using currently available remote sensing technology because traditional ship-based field sampling and analysis are very limited in both space and temporal frequency. Satellite ocean color sensors, such as Sea-viewing Wide Field-of-view Sensor (SeaWiFS), are ideal instruments for detecting and monitoring these blooms because they provide relatively high frequency synoptic information over large areas. Thus, the present study attempts to evaluate the red tide index methods (previously developed by Ahn and Shanmugam et al., 2006) to identify potential areas of red tides from SeaWiFS imagery in Korean and neighboring waters. Findings revealed that the standard spectral ratio algorithms (OC4 and LCA) applied to SeaWiFS imagery yielded large errors in Chl retrievals for coastal areas, besides providing false information about the encountered red tides in the focused waters. On the contrary, the RI coupled with the standard spectral ratios yielded comprehensive information about various ranges of algal blooms, while RCA Chl showing a good agreement with in-situ data led to enhanced understanding of the spatial and temporal variability of the recent red tide occurrences in high scattering and absorbing waters off the Korean and Chinese coasts. The results suggest that the red tide index methods for the early detection of red tides blooms can provide state managers with accurate identification of the extent and location of blooms as a management tool.

• Asian Pacific Journal of Cancer Prevention
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• 제14권3호
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• pp.1879-1887
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• 2013

To investigate the level of genotoxicity over Bangkok atmosphere, $PM_{10}$ samples were collected at the Klongchan Housing Authority (KHA), Nonsree High School (NHS), Watsing High School (WHS), Electricity Generating Authority of Thailand (EGAT), Chokchai 4 Police Station (CPS), Dindaeng Housing Authority (DHA) and Badindecha High School (BHS). For all monitoring stations, each sample covered a period of 24 hours taken at a normal weekday every month from January-December 2006 forming a database of 84 individual air samples (i.e. $12{\times}7=84$). Atmospheric concentrations of low molecular weight PAHs (i.e. phenanthrene, anthracene, pyrene and fluoranthene) were measured in $PM_{10}$ at seven observatory sites operated by the pollution control department of Thailand (PCD). The mutagenicity of extracts of the samples was compared in Salmonella according to standard Ames test method. The dependence of the effects on sampling time and on sampling location was investigated with the aid of a calculation of mutagenic index (MI). This MI was used to estimate the increase in mutagenicity above background levels (i.e. negative control) at the seven monitoring sites in urban area of Bangkok due to anthropogenic emissions within that area. Applications of the AMES method showed that the average MI of $PM_{10}$ collected at all sampling sites were $1.37{\pm}0.10$ (TA98; +S9), $1.24{\pm}0.08$ (TA98; -S9), $1.45{\pm}0.10$ (TA100; +S9) and $1.30{\pm}0.09$ (TA100; -S9) with relatively less variations. Analytical results reconfirm that the particulate PAH concentrations measured at PCD air quality monitoring stations are moderately low in comparison with previous results observed in other countries. In addition, the concept of incremental lifetime particulate matter exposure (ILPE) was employed to investigate the potential risks of exposure to particulate PAHs in Bangkok atmosphere.

• 대한지리학회지
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• 제32권2호
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• pp.175-195
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• 1997

본 연구는 미국의 대도시지역이 경험하고 있는 산업재구조화와 신이민집단의 적응양태를 연계시켜 이해하기 위하여. 로스엔젤레스, 뉴욕. 시카고. 그리고 애틀란타를 선정하고 이들 지역에 거주하는 중남미계와 동양계의 취업분포와 거주양태를 분석하였다. 분석 결과 이들의 산업별 취업분포는 모든 분야에 나타나 대체적으로 전체인구와 유사한 분포를 보이나 제조업, 서비스업 그리고 소매업에서 비교적 높은 집중도를 보이고 있다. 이들의 거주집중지역은 도심 주변과 더불어 외곽 지역에도 나타나고 있다. 이는 기존 유럽계 이민집단이 제조업에 편중적으로 고용되고 도심 주변에 거주지를 집중시키던 적응양식과는 다른 모습을 보이고 있으며,도시별로 다양하게 전개되고 있다. 따라서 신이민집단의 적응양태에 대한 올바른 이해는 정착지역이 경험하고 있는 산업재구조화와 이에 따른 공간상의 변화 그리고 집단 내부의 다양성을 고려한 관점에 기초해야 함을 제시하고 있다.