• Title/Summary/Keyword: CHANGE OF URBAN ENVIRONMENT

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A Study of GNSS Performance Enhancement using Correction Estimation and Visible Satellites Selection (보정량 추정 및 가시위성 선정 기법을 이용한 위성항법 성능개선 연구)

  • Bong, Jae Hwan;Jeong, Seong-Kyun
    • The Journal of the Korea institute of electronic communication sciences
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    • v.17 no.5
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    • pp.995-1002
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    • 2022
  • Global Navigation Satellite System(GNSS) is a convenient system that acquires position and time information of a receiver if only satellite signals can be received anywhere in the world. However navigation signals include errors and a position error occurs according to the reception state of the signal. Also, a position error is affected by the geometric arrangement of the satellites. Therefore a receiver position performance varies by the number and status of visible satellites The condition of satellite signals is not good when the satellite rises or sets and the position change of receiver occurs when the signal is blocked by an obstacle such as a building in the urban area. In this paper, we proposed methods to improve the GNSS performance by using pseudorange correction method estimating the correction amount and the visible satellites selection method. By applying the proposed methods to an environment in which the number of visible satellites changes variously, the performance enhancement was verified.

Applicability of Geo-spatial Processing Open Sources to Geographic Object-based Image Analysis (GEOBIA)

  • Lee, Ki-Won;Kang, Sang-Goo
    • Korean Journal of Remote Sensing
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    • v.27 no.3
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    • pp.379-388
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    • 2011
  • At present, GEOBIA (Geographic Object-based Image Analysis), heir of OBIA (Object-based Image Analysis), is regarded as an important methodology by object-oriented paradigm for remote sensing, dealing with geo-objects related to image segmentation and classification in the different view point of pixel-based processing. This also helps to directly link to GIS applications. Thus, GEOBIA software is on the booming. The main theme of this study is to look into the applicability of geo-spatial processing open source to GEOBIA. However, there is no few fully featured open source for GEOBIA which needs complicated schemes and algorithms, till It was carried out to implement a preliminary system for GEOBIA running an integrated and user-oriented environment. This work was performed by using various open sources such as OTB or PostgreSQL/PostGIS. Some points are different from the widely-used proprietary GEOBIA software. In this system, geo-objects are not file-based ones, but tightly linked with GIS layers in spatial database management system. The mean shift algorithm with parameters associated with spatial similarities or homogeneities is used for image segmentation. For classification process in this work, tree-based model of hierarchical network composing parent and child nodes is implemented by attribute join in the semi-automatic mode, unlike traditional image-based classification. Of course, this integrated GEOBIA system is on the progressing stage, and further works are necessary. It is expected that this approach helps to develop and to extend new applications such as urban mapping or change detection linked to GIS data sets using GEOBIA.

A Study on the Change of Quality in a Residential Sector of Single Person Households in Seoul during the COVID-19: Analyze Variable Importance and Causality with Artificial Neural Networks and Logistic Regression Analysis (서울시 1인 가구의 코로나 19 전후 주거의 질 변화 연구: 인공신 경망과 로지스틱 회귀모형을 활용한 변수 중요도 및 인과관계 분석)

  • Jaebin, Lim;Kiseong, Jeong
    • Land and Housing Review
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    • v.14 no.1
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    • pp.67-82
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    • 2023
  • Using the Artificial Neural Network model and Binary Logistic Regression model, this study investigates influence factors on the quality of life in terms of housing environment during the COVID-19 in Seoul. The results show that the lower the satisfaction level of housing policy, the lower the quality of life in the employment field and the lower the quality of residential field. On the other hand, permanent workers and self-employed respondents have experienced improvement in residential quality during the pandemic. A limitation of this study is associated with disentangling the causal relationship using the 'black box' characteristics of ANN method.

Effect of Bedding Layer and Clogging on Drainage Capacity of Pervious Sidewalk Block in Unsaturated Condition (노반 및 공극 막힘 현상에 따른 투수성 보도블록의 불포화 상태에서의 배수 성능에 관한 실험적 연구)

  • Seo, Dawa;Yun, Tae Sup
    • Journal of the Korean Geotechnical Society
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    • v.32 no.5
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    • pp.37-48
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    • 2016
  • This study aims to figure out the behavior of runoff and drainage of pervious sidewalk block in actual construction environment by experiments. The specimens with surface layer and bedding layer are subjected to the drainage test by considering unsaturated condition and unique rainfall condition in urban areas. The repeated drainage test and clogging test were conducted with time intervals, and 3D X-ray CT image analysis and evaporation test were carried out for a quantitative analysis of drainage test. The results present that the spatial distribution of pores by evaporation for time intervals induces runoff. Especially, the bedding layer under the block is significantly critical in overall hydraulic behavior such as drainage and evaporation compared to the surface layer. Moreover, the sediments in pores promote the change in pores by evaporation and this induces deteriorated drainage capacity which is hard to recover. In addition, it is revealed that the maximum runoff height grows as the drainage capacity declines depending on the pre-wetting condition.

Modeling flood and inundation in the lower ha thanh river system, Binh dinh province, vietnam

  • Don, N. Cao;Hang, N.T. Minh
    • Proceedings of the Korea Water Resources Association Conference
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    • 2016.05a
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    • pp.195-195
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    • 2016
  • Kon - Ha Thanh River basin is the largest and the most important river basin in Binh Dinh, a province in the South Central Coast of Vietnam. In the lower rivers, frequent flooding and inundation caused by heavy rains, upstream flood and or uncontrolled flood released from upstream reservoirs, are very serious, causing damage to agriculture, socio-economic activity, human livelihood, property and lives. The damage is expected to increase in the future as a result of climate change. An advanced flood warning system could provide achievable non-structural measures for reducing such damages. In this study, we applied a modelling system which intergrates a 1-D river flow model and a 2-D surface flow model for simulating hydrodynamic flows in the river system and floodplain inundation. In the model, exchange of flows between the river and surface floodplain is calculated through established links, which determine the overflow from river nodes to surface grids or vice versa. These occur due to overtopping or failure of the levee when water height surpasses levee height. A GIS based comprehensive raster database of different spatial data layers was prepared and used in the model that incorporated detailed information about urban terrain features like embankments, roads, bridges, culverts, etc. in the simulation. The model calibration and validation were made using observed data in some gauging stations and flood extents in the floodplain. This research serves as an example how advanced modelling combined with GIS data can be used to support the development of efficient strategies for flood emergency and evacuation but also for designing flood mitigation measures.

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A Study on U-Service for Security in U-City Newtown Planning (신도시계획의 계획지표를 반영한 U-City의 U-방범서비스 개선방안 연구)

  • Yoon, Hyo Jin
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.5D
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    • pp.645-654
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    • 2009
  • This study started with necessity of historical spatial planning skills in U-city planning. Though U-city technology and information are very important, U-city development should be considered on the base of various experience of spatial planning. This study explored spatial planning indexes change in the recent newtown plans. In particular, safety and security were intensively analyzed. In addition, many theories on safe urban space, ubiquitous technology, traditional defensible space, and CPTED (Crime Prevention through Environmental Design) are compared. The findings are as follows. First, each planning is not integrated and there is lack of network among each planning. Specifically, from the crime prevention perspective, there is only mechanical monitoring such as CCTV without architectural approach. Even though CCTV is social needs, it is necessary to adopt it with architectural environment in order to improve the synergy effect of spatial planning and non-spatial planning.

Protect Blue Carbon Biomass Habitat and Create a Carbon Reducing Coastal City (블루카본 바이오매스 서식지를 중심으로 한 탄소저감형 해안도시 조성의 필요성)

  • Sun-Ah Hwang
    • Journal of Navigation and Port Research
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    • v.47 no.3
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    • pp.134-146
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    • 2023
  • The issue of 'carbon reduction' can be said to be one of the most important issues worldwide. For efficient carbon reduction, it is necessary to consider ways to increase absorption and reduce emissions. Accordingly, much attention has been paid to increasing carbon absorption using blue carbon biomass. Blue carbon biomass refers to an ecosystem related to blue carbon, which has a higher carbon absorption rate than inland ecosystems and a longer collection period. It is very efficient in reducing carbon. Therefore, in this study, a current status survey was conducted on domestic and foreign policies, studies, and plans related to the preservation of blue carbon biomass habitats. Basic research was conducted to prepare plans for future preservation of blue carbon biomass habitats suitable for the domestic environment.

The Change of Riverside Vegetation by Construction of Ecological Stream in Suwoncheon, Gyeonggi Province (경기도 수원천 생태하천 복원사업 이후 식생변화 연구)

  • Choe, Il-Hong;Han, Bong-Ho;Ki, Kyong-Seok
    • Korean Journal of Environment and Ecology
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    • v.24 no.6
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    • pp.723-734
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    • 2010
  • This study aims to analyze the change in vegetation for 10 years after the construction, targeting Suwoncheon, the first domestic ecological stream construction project. As for the section for the study, the section from Gyeonggi bridge to Youngyeon bridge, the first restoration project section, was targeted. The research districts consisted of 3 districts depending on topographical structure. Investigation check cosisted of cross-sectional topographical structure, vegetation status and the structure of herbaceous plant community. As for the cross-sectional topographical structure of the stream, the width of entire stream was 26.5~28.0m and water channel is 10~20m. The area for hydrophilic space was securing spacious riverside. Upper stream of reservoir beam was shallow and slow in reservoir area above weir. Lower stream of reservoir beam, the width of water channel was narrow and ripples were formed. Among species, 9 plants were planted and 6 species plants including Salix gracilistyla, Phragmites communis and Zoysia japonica were planted at the time of construction. In the water side, there were 2 species, such as Zoysia japonica and Trifolium repens, etc, still remained after seeding at the time of constrcution. The planted plants which were observed through this investigation, were 2 species such as Festuca arundinacea and Dactylis glomerata. Apart from the planted plants, arid climate herbaceous plant such as Setaria viridis and Artemisia princeps var. orientalis formed power and the naturalized species variously emerged in 15 species. For revetment, natural stone stacking method was condicted and Salix gracilistyla, Aceriphyllum rossii, etc were planted. But all the planted plants disappeared and now it was covered with Equisetum arvense and Humulus japonicus. It was because that the base for growth and development of the plants was not constructed at the time of restoration in a way of attaching natural stones onto the concrete base. In the water channel, various wetland species including Typha orientalis, Acorus calamus var. angustatus and Phragmites communis, etc, were planted but only Salix gracilistyla, Phragmites communis and Zizania latifolia remained. As for species of the autochthons, Persicaria thunbergii was dominant. In the lower stream of reservoir beam, Humulus japonicus formed forces. In the hydrophilic space, it was necessary to direct the landscape of in-stream vegetation in cosideration of users. For this, planting Miscanthus sacchariflorus in a community was proposed. In the upper stream of reservoir beam, suplementary screen seeding was necessary so that Zizania latifolia, Typha orientalis and Phragmites communis can fit the depth of water. In the Lower stream of reservoir beam, it was necessary to constantly manage Humulus japonicus so that the wetland autochthons species, such as Phragmites communis and Persicaria thunbergii can establish power more stably.

Management Planning and Change for Nineteen Years(1993~2011) of Plant Community of the Pinus densiflora S. et Z. Forest in Namhan Mountain Fortress, Korea (남한산성 소나무림의 19년간(1993~2011년) 식생구조 변화와 관리방안)

  • Lee, Kyong-Jae;Han, Bong-Ho;Lee, Hak-Gi;Noh, Tai-Hwan
    • Korean Journal of Environment and Ecology
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    • v.26 no.4
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    • pp.559-575
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    • 2012
  • This study, targeting Namhan Mountain Fortress which was designated as a No. 57 national historic site and placed on the World Heritage Tentative List in 2010, was intended to identify the change of vegetation structures by reviewing past references, pictures, research data and additionally conducting a site survey. Also, it was designed to draw up measures for restoring vegetation suitable for historically and culturally valuable Namhan Mountain Fortress. According to the biotope mapping of study site, Quercus spp. forest distributed a greatest part of area with 40.8% of $2,611,823m^2$. Pinus densiflora forest, highly likely to go through ecological succession, was dispersed in the whole region of Cheongryangsan, the area from West Gate to North Gate and the ranges between South Gate to Cheongryangsan with taking 16.5%. Pinus densiflora forest with a low probability of succession amounted to 4.7% and was dispersed mainly in the forest behind Namhansan elementary school. Pinus densiflora going on the ecological succession is distributed a portion of 2.9%. And the currently dying out Pinus densiflora forest amounted to 2.1%. As a result of analysis of the vegetation structure for 19 years, the succession from Pinus densiflora forest to Pinus densiflora and succession from Quercus spp. mixed forest to Quercus spp. forest to Carpinus laxiflora forest were predicted. Additionally, Quercus spp. expanded its dominance over time. According to the characteristics of each classified zone, the site was categorized into $553,508m^2$ area of Pinus densiflora forest area for the landscape maintenance, $114,293m^2$ area of Pinus densiflora forest area for the landscape restoration, $205,306m^2$ area of Pinus densiflora forest area for the disclimax, and $1,169,973m^2$ area of Pinus densiflora forest area for inducing ecological succession.

A Study on the Analysis of Officials' Cognition on the Management of Green Belt - With Special Reference to Seoul Metropolitan City - (개발제한구역 관리에 대한 공무원 인식 분석 - 서울특별시를 대상으로 -)

  • Maeng, Chi-Young;Cho, Se-Hwan
    • Journal of the Korean Institute of Landscape Architecture
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    • v.36 no.6
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    • pp.126-133
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    • 2009
  • This study aimed to propose the base data to promote the green belt(thereafter GB) regulations and management in Korea. The research took the methods of analysis of citizen's official petitions to the once, of interviews and questionnaire to the of officials of Seoul Metropolitan City who is under the job of managing the GB. The conclusions were as follows. The officials did understand function and necessity of GB well. They especially, put the importance of the purpose of GB on the prevention of the environment of the city and prevention of concentration of population, They recognized that they suffered from the overloaded job on the management of GB in quantity and quality. The seriousness of illegal action of the change of land use, piling-up of materials and productions on the forbidden land, using exclusively of warehouses for agriculture as for commerce and enlarging the area of warehouse with application of leased land for agriculture instead of the agricultural land in law were detected in the officials' cognition. The officials proposed some ideas to prevent above mentioned illegal actions including forcing a person who did illegal actions to punish money to restore environment etc..