• Title/Summary/Keyword: Large urban areas

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Application of UAV images for rainfall-induced slope stability analysis in urban areas

  • Dohyun Kim;Junyoung Ko;Jaehong Kim
    • Geomechanics and Engineering
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    • v.33 no.2
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    • pp.167-174
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    • 2023
  • This study evaluated slope stability through a case study to determine the disaster risks associated with increased deforestation in structures, including schools and apartments, located in urban areas adjacent to slopes. The slope behind the ○○ High School in Gwangju, Korea, collapsed owing to heavy rain in August 2018. Historically, rainwater drained well around the slope during the rainy season. However, during the collapse, a large amount of seepage water flowed out of the slope surface and a shallow failure occurred along the saturated soil layer. To analyze the cause of the collapse, the images of the upper area of the slope, which could not be directly identified, were captured using unmanned aerial vehicles (UAVs). A digital elevation model of the slope was constructed through image analysis, making it possible to calculate the rainfall flow direction and the area, width, and length of logging areas. The change in the instability of the slope over time owing to rainfall lasting ten days before the collapse was analyzed through numerical analysis. Imaging techniques based on the UAV images were found to be effective in analyzing ground disaster risk maps in urban areas. Furthermore, the analysis was found to predict the failure before its actual occurrence.

Park Disposition Problems and Alternatives on the Basis of the Neighborhood Units Theory in Japan Metro-Cities -New Approach to the Disposition Theory of Urban Public Parks- (일본지방도시를 사례로 본 근린제 공원배치의 문제 및 그 개선방안 -도시공원 배치이론에 대한 새로운 접근-)

  • 박구원
    • Journal of the Korean Institute of Landscape Architecture
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    • v.32 no.2
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    • pp.36-54
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    • 2004
  • The disposition of public parks pursue proper distribution and hierarchy formations on the basis of the neighborhood units theory. However, problems like price of land has brought about a large gap between theories and real conditions. This paper examines the problems of the practical disposition and disposition standards of public parks to solve these contradictions with reference to examples in Japan metro-cities. Study results are as follows; 1) The existing disposition theories are based on the district-boundary of men’s acting and settling down. Therefore, the disposition standards of large-scale parks or special parks beyond the humane scale have not been explained exactly. 2) As city sizes have expanded, these large-scale parks have developed greatly, however, they are located out of urban areas on the ground of nature’s geographical features. As a result, many small parks developed in urban areas. This extreme phenomenon of location would break up proper distribution and hierarchy. 3) Large parks over 4 ha not only take an important role in forming greenbelts but their location is also mainly based on their natural geographical features so that they are absorbed into the network -structure of greenbelts. 4) It is suggested that in planning parks, location and size of large parks over 4 ha should be selected and decided in the relation not with parks but with greenbelts. Parks of 4 ha or below are properly disposed. Also, these parks take a great role in forming the district boundary for settling down. Accordingly, proper distribution and hierarchy formation needs to be based on established neighborhood as they were previously.

The Effect of Atmospheric Flow Field According to the Urban Roughness Parameter and the Future Development Plan on Urban Area (도심 실제 거칠기 적용과 장래 도심 개발계획에 따른 국지 기상장 변화 수치 모의)

  • Choi, Hyun-Jung;Lee, Hwa-Woon;Kim, Min-Jung
    • Journal of Environmental Science International
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    • v.19 no.6
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    • pp.703-714
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    • 2010
  • In this study, we analyzed the impact of orographic and thermal forcing on the atmospheric flow field over the urban metropolitan areas on urban artificial buildings and future development plan. Several numerical experiments have been undertaken in order to clarify the impacts of the future development plan on urban area by analyzing practical urban ground conditions, we revealed that there were large differences in the meteorological differences in each case. The prognostic meteorological fields over complex areas of Seoul, Korea are generated by the PSU/NCAR mesoscale model(MM5). we carried out a comparative examination on the meteorological fields of topography and land-use that had building information and future development plan. A higher wind speed at daytimes tends to be forecasted when using new topography and land use data that have a high resolution with an appropriate limitation to the mixing height and the nocturnal boundary layer(NCB). During nighttime periods, since radiation cooling development is stronger after development plan, the decreased wind speed is often generated.

Constructing 3D Models and Virtual Reality Contents of CheongGyeCheon (청계천의 3차원모델 및 가상현실컨텐츠 제작)

  • Lee Im-Pyeong;Choi Yun-Soo;Kwon Moon-Seong;Choi Kyoung-Ah
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • 2006.04a
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    • pp.501-506
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    • 2006
  • With the development of Geospatial Technology (GT), many countries and industries have been expanding their investment in constructing a cyber territory. As the critical components of this cyber territory, three-dimensional models and virtual reality contents based on these models of urban areas in particular have been considered. These models and contents can be intensively used for a city to decide the policies efficiently and to attract the interests of peoples while planning and performing large projects. In this study, we have thus constructed the 3D models and virtual reality contents of the large areas along the CheongGye stream to visualize the environment of these areas before and after the CheongGyeCheon restoration project being completed. Furthermore, we propose efficient methods to construct and visualize these large models, such as tile mapping and multiple LOD application.

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Estimation of Surface Temperature of the Urban Area in Cheongju Using ASTER Data (ASTER에 의한 청주시주변의 지표면온도 추정)

  • Park, Jong-Hwa;Na, Sang-Il
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2005.10a
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    • pp.563-568
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    • 2005
  • Land surface temperature (LST) for large areas can only be derived from surface-leaving radiation measured by satellite sensors. These measurements represent the integrated effect of the surface and are superior to point measurements on the ground, e.g. in Urban Heat Island. ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) is an imaging instrument that is flying on the NASA's Terra satellite launched in December 1999. ASTER acquires 14 spectral bands and can be used to obtain detailed datas of land surface temperature, emissivity, reflectance and elevation. Spatial resolution of 90m of TIR channels of ASTER is useful when we analyze the spatial variations of surface heat fluxes in urban areas. The purpose of this study is to extract the LST using ASTER TIR channels.

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A Study on Out-migration of Rural People (농촌(農村)의 인구전출(人口轉出)에 관(關)한 연구(硏究))

  • Paek, Kee-Sung
    • Journal of Preventive Medicine and Public Health
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    • v.7 no.1
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    • pp.197-201
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    • 1974
  • The rapid economic development of Korea since 1960 has also brought a rapid urbanization process, and recently many rural areas have begun to show actual depopulation, in which particularly the young, productive and high educated groups are leaving for cities. More than 70% of migrators go to large cities such as Seoul, Pusan and Taegu. Their main motives for migration are to seek a job in urban areas. The study showed following results; The rate of migration a year was 1% of total population. Regarding the age of migrators belong to between 10-39 years old, especially migrator aged 10-29 years are comprised 87%. The educational level of migrators was a little higher than that of the residents. Considering the sibling order of migrators, the traditional value system for first son seemed to change. Concerning the place of destination, more than 70% of migrators moved to large cities such as Seoul. Pusan and Taegu. The main motivation of migration was to seek a job in urban areas. The occupation at the place of destination were factory workers, employee at company, students, salesmen, farmers and public officials in that order.

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A Study on the Impact of HVDC Transmission System to Interconnect Large-scale Power Generation Plants to Power Grid in Korea (HVDC 송전을 이용한 동해안 신규전원의 수도권 계통 연계방안에 대한 연구)

  • Han, Su-Young;Gwon, Do-Hun;Chung, Il-Yop;Lim, Jae-Bong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.12
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    • pp.1647-1656
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    • 2013
  • Although the demand for electricity has been increasing these days, it becomes more difficult to find new sites for large-scale power generation plants near urban areas due to environmental and economic issues. Therefore, new power plants are forced off to rural or desolate coastal areas. As a result, there is significant regional imbalance in power generation and consumption between urban and rural areas in South Korea. This paper investigates the feasibility of high-voltage DC (HVDC) system as a candidate for electric power transmission system from east-coastal sites to metropolitan area. To this end, this paper analyzes transient stability and dynamic impact of a HVDC transmission system and compares the results to conventional high-voltage AC (HVAC) transmission systems via PSS/E simulation. This paper also examines the effect of HVDC system to voltage variation and low-frequency resonance in the neighboring buses in the grid using ESCR(Effective Short Circuit Ratio)과 UIF(Unit Interaction Factor) indices.

An Assessment of Landscape Ecological Value of Greenbelt Areas in the Seoul Metropolitan Area (수도권 개발제한구역의 경관생태학적 가치평가)

  • Oh, Kyushik;Park, Jihye;Lee, Dongwoo
    • Journal of Environmental Impact Assessment
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    • v.20 no.6
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    • pp.867-878
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    • 2011
  • Development restriction areas (greenbelt areas) of Korea were recognized in 1970 as a means to control urban sprawl and conserve the natural environment. Although there have been some achievements, for a long time many planners and residents have requested a redefining of the green belt due to individual property rights restrictions and urban management problems. In fact, a lot of the greenbelt area is being destroyed by urban development. Therefore, conservation of ecological spaces in the green belt is needed to maintain urban naturalness. In this regard, this study suggests efficient methods to manage the greenbelt through the adoption of a landscape ecological value assessment. The greenbelt of the Seoul Metropolitan Area (SMA) is represented as the case study because there has been mounting pressure to develop the area in Korea. In this study, the assessment of the landscape ecology in the greenbelt area focuses on landscape structure and function. The assessment consists of the following steps: First, patches were derived by NDVI analysis using landsat remote sensing data. Second, characteristics of the patches were quantified by analyzing the landscape structure, such as patch size and shape index. Lastly, the gravity model and least cost path analysis to assess connectivity were applied to evaluate the landscape function in the green belt areas. The assessment result showed that 48.45% of green belt area should be conserved to maintain ecological stability and function. Moreover, major ecological networks were identified near the large patches in the northern and southern areas. However, relative low ecological values were identified in the western part of the green belt area due to the lack of green spaces. Furthermore, some development plans in the green belt were also identified near the conservation area. Based on these results, the restoration needed areas to enhance ecological value in green belt were displayed. This study suggests efficient management of the greenbelt area, which is disappearing as a result of urban development. The area for conservation chosen in this study should be managed carefully in urban planning. Finally, the results of this study can be used in green belt polices and plans for the promotion of ecological naturalness and stability.

A Study of the Health Status of Elderly Residing in Large city, Medium and Small city, Rural areas in Korea (대도시, 중소도시, 농촌 노인의 건강상태에 관한 연구)

  • 최영희;신윤희
    • Journal of Korean Academy of Nursing
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    • v.21 no.3
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    • pp.365-382
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    • 1991
  • This study was designed to measure the physical, mental-emotional and social health status of elderlies according to rural areas, medium - small cities, and large city environment. Data collection was done from July 18 to August 17 1990. The subjects were a convenience sample after their place of residence was stratified into large, medium- small cities and rural areas. Those who attended elderly centers in Seodaemun, Mapo, and Kangnam districts in Seoul were considered to be residents of a large city and interviewed by trained research assistants and student nurses. Elderlies living in Chungju, Jinju, Chuncheon, and Jeonju cities were coded as residents of medium-small cities and were interviewed by professors of nursing colleges. Rural residents were interviewed by the community health practioners working in community health clinics in North and South Kyongsang, North and South Jeolla, and Kyonggi provinces. The tool used in this study was the health assessment tool developed by Choi, Young Hee in 1990. This tool was organized into 20 physical health status, 17 mental - emotional health status, and 37 social health ststus items. Physical health status items consisted of six factors - personal hygiene activity ability, external activity utilizing traffic, mass media, and spare time ability, sexual ability, digestive system related ability, sexual ability, sensory ability, and elimination ability. Mental - emotional health status items consisted of two factors - mental health factor and emotional health factor. Social health status items consisted of seven factors -grandparental role ability, parental role ability, spoused role ability, friendship role ability, kinship role ability, group member role ability, and religious believer role ability. Data Analysis included frequencies, percentage, mean, standard deviation, ANOVA, and chi - square test. The results of the analysis are as follows : 1. The mean physical health status score for large city residents was 4.1132, for rural residents 4.0787, and for medium and small city residents 3.9565. There were significant differences according to residential area for personal hygiene activity ability, external activity ability, sexual ability, and digestive system related ability items 2. The mean mental -emotional health status score for rural residents was 3.8291, for medium and small city residents 3.7967, and for large city residents 3.7807. There was a significant difference according to residential area in the mental health ability item. 3. The mean social health status score for medium and small city residents was 3.0000, for rural residents 2.9362, and for large city residents 2.8960. There were significant differences according to residential area for kinship role ability and religious believer role ability items. The following conclusion was derived from the above results 1. The physical health status of elderlies residing in medium - small cities and in rural areas was lower than that of those residing in Seoul, a large urban area. Therefore, more medical facilities are needed in rural area so as to monitor their health, prevent disease, and promote their health. 2. The mental -emotional ststus and social health status of elderlies residing in the large city were lower than that of those residing in medium - small cities and rural areas. This may reflect weakening of the strong traditional family bond that may happen with urbanization. Continued support for elderly parents is essential and education should emphasize the traditional cultural norm and value of filial piety. 3. Facilities and programs for elderly are needed so that they may spend their time more valuably in their urban environment.

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Regional Difference in Outpatient Service Utilization for Chronic Diseases among the Elderly (고령층 만성질환 외래이용의 지역 간 변이)

  • Yun, Heesuk
    • Health Policy and Management
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    • v.24 no.2
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    • pp.128-135
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    • 2014
  • Background: With ageing and growing importance of disease management system, it is necessary to investigate the extent of regional difference in service utilization for chronic diseases among the elderly and to reflect it in designing the system. Methods: A multiple regression analysis and descriptive statistics analyses were employed using patient survey, which covers nationwide health facilities and their users. Results: While the differences in the rate of service utilization/utilization outside living area between urban and rural areas or between income levels are not large, considerable variations are observed within urban or rural areas and within income groups. Conclusion: This results suggest that it is important to subsidize economically disadvantaged segments of the population and residents of less-favored areas to be better-equipped for chronic disease management in order to prevent the development of severe ailments and the need for treatment at higher-level medical institutions. Improvements to the service infrastructure in vulnerable regions are essential.