• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.2
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• pp.11-20
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• 2010

In this study, the effects of stand height growth on GIS-based viewshed analysis were investigated. DSM was created by combining stand height layers on DEM using map algebra functions. In developing the tree height layers, the digital forest-type maps, forest site maps and stand yield tables of Korea Forest Research Institute were used. The time horizon for viewshed analysis were 40 years. Two viewpoints in crossings of downtown for viewshed analyses were chosen using a projective mapping technique. The effects of tree height growth over time on visibility were measured in terms of the depth of blind areas and the area of visible regions. The results of viewshed analyses show that 17% of visible regions is reduced when we use DSM instead of DEM. As the tree height grows, the visibility gets worse and worse and the depth of blind area increases.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.1
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• pp.40-48
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• 2011

The purpose of this study is to contribute enhancing the accuracy of viewshed analysis through the explanation for an analysis method of viewshed analysis using GIS. According to previous studies, the visible area using digital terrain in viewshed analysis depends on a visible interest area, scale of terrain, spatial resolution and surface data. In this study, we used trend analysis and RMSE analysis in order to find the effect of a visible interest area, scale of terrain, etc in viewshed analysis. Results of this study are as follows. First, the result of viewshed analysis depends on a visible interest area, scale of terrain, spatial resolution, surface data such as previous studies. Second, the results in forest area are reliable than those of flat area in terms of a visible interest area. Third, the results based on raster grid data are stable than those of TIN(triangulated irregular network) in terms of input surface data. Fourth, according to the result of trend and RMSE analysis, the spatial resolution for analysis is differently applied to different scales digital terrain map in viewshed analysis. In detail, it is desirable that the spatial resolution is set less than 10m(in the case of 1/1,000 digital terrain map), 20m(in the case of 1/5,000 map), 30m(1/25,000 map).

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.787-796
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• 2012

This study, as a purpose of viewshed anaiysis is selected for the view route, View of the target yunseondo wonlim (scenic sites No.34) located in the terrain ridge. Using GIS Viewshed analysis carried out and the results reflect the view route was selected. The basic research for this study, the scenic sites such as the natural and cultural resources for the efficient and optimized to create the route view. Viewshed Analysis results could be summarized as follows: Along a scenic sites located inside the main ridge Viewshed analysis was carried out. This overlapping the cumulative results are Leading to Nakseojae(樂書齎) Seyeonjeong(洗然亭) from space in the visible frequency higher natural villages of the district. Selected the view route and were on the road and in the topographic map nesting along Visible high-frequency region. Based on the results of the nested Viewshed major selected six points Viewshed analysis was carried out. Resource for the surrounding landscape. Results determine whether the visibility of the surrounding landscape was identified as the viewable area appears good. Finally Viewshed Analysis results for six points in the final review.

• Journal of the Korean Institute of Landscape Architecture
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• v.23 no.3
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• pp.1-14
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• 1995

The aspect of visual accessibility to urban green spaces is an important factor because it contributes making pleasant environment by increasing the visual experience of nature in urban environment. But we have tried neither to consider nor to measure it. Since he concept of visual accessibility has not formally defined yet, it was operationally defined in this study. And then the model of measuring visual accessibility was suggested and verified through the case study on neighborhood parks in Seoul. The findings are as follows : 1) The concept of visual accessibility is defined as opportunity and potentiality to observe green spaces. 2) The model of measuring visual accessibility deals with not only adjacent area but also viewshed area. In adjacent area, considering factors are the area of road adjacent to green spaces and the area of exposed green spaces. In viewshed area, considering factors are the area of road located in viewshed area, the area of exposed green spaces, and the weight according to observing distance. 3) The final model of measuring visual accessibility suggested in this study is as follows.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.5
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• pp.343-353
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• 2013

Recently, the landscape change by development has become more important and it's been stipulated that environmental effects evaluation must include LIA which reflects the said issue. Even though the selection of viewpoints which have the biggest impact on LIA result is stipulated in accordance with related rules, the criteria are inconsistent. Therefore, LIA experts' or project developers' subjective opinions have been very influential. In this case, wrong viewpoints which do not meet the selection criteria could be selected based on a discretionary interpretation on them, which could in turn substantially reduce an accuracy and reliability of the LIA results. Therefore, this research suggested the reverse-viewshed frequency technique as method that can be verified accuracy and reliability of viewpoints. And it has comparatively analyzed effective viewpoints using reverse-viewshed frequency analysis on viewpoints which were selected for LIA. As a result, the average validity was just 58% of total viewpoints used in construction sites. And the validity of viewpoints decreased as viewshed frequency increased. Based on results above, it was able to verify that the unreasonable points of a substantial proportion have been used as viewpoints in LIA process.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.3
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• pp.126-135
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• 2011

In this study, the algorithm for priority area of forest fire surveillance was developed to enhance the effectiveness of fire detection. The high priority surveillance area for forest fire detection was defined as the area with not only low value of viewshed analysis of the lookouts and detection cameras but also high fire occurrence probability. To build the priority map, fuzzy function and map algebra were used. The analysis results of Bonghwa-gun, Gyeongbuk Province, showed that the surveillance priority of central and southern area is higher than north area. This algorithm could be used in the allocation of fire prevention resources and selection of suitable point for new fire detection system.

• Journal of Environmental Science International
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• v.12 no.10
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• pp.1025-1032
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• 2003

The purpose of this study is to analyze the characteristics of the urban landscape by CG(Computer Graphic) pictures and visibility analysis. In this study, the CG picture was created by using zoning data and DEM(Digital Elevation Model) on Chunchon city. The landscape type was classified into three by cluster analysis using the area rate of the element which constitutes CG picture. Visible analysis used DEM as fundamental data, and was performed by using GIS(Geographic Information System). And the frequency seen on viewshed was classified into five grades. The result of this study are as follows: 1. The area rate of the element which constitutes CG picture was high development restriction zone(43%) in type 1, green land area(39%) in type 2, and city area(24%) in type 3. 2. In the analysis results of GIS visibility analysis, it turns out that Euiam lake is important area on the landscape in all types. 3. The land use of high frequency seen on viewshed was water area, residential area in type 1, development restriction area, park area in type 2, and development restriction zone, water area in type 3.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.1
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• pp.80-87
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• 2009

The purpose of this study is to analyze the MAUP's effect in visibility analysis using GIS. MAUP normally occurs in the process in terrain spatial analysis including visibility analysis. There are two different types of grid data(based on digital map and Digital Terrain Elevation Data) and 10 different types of areal units are made for modeling, such as $5m{\times}5m,\;10m{\times}10m,\;15m{\times}15m,\;20m{\times}20m,\;25m{\times}25m,\;30m{\times}30m,\;35m{\times}35m,\;40m{\times}40m,\;45m{\times}45m,\;50m{\times}50$. By analyzing the result, it was possible to observe varying viewshed areas according to different grid cell sizes and the viewshed area did not varied linearly as expected. From a general point of view, smaller unit data map out the real world in more detail, but the results of modeling do not always reach a good conclusion when data are used in modeling for terrain analysis because of the MAUP' effect. The grid cell sizes of 30m or less seems to be adequate for visibility analysis, including terrain analysis considering vegetation heights.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.2
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• pp.65-75
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• 2018

This study analyzes the characteristics of the urban landscape changes as a result of the introduction of private parks among the long-term uncollected urban planning facilities and enables the analysis of the characteristics of the urban landscape changes as a result of the introduction of private parks, and applied to the private park projects. The DSM with its building was established for the quantitative landscape analysis to examine the view ratio using the stacked visible analysis. The analysis showed that Jikdong Park had a high frequency of view from downtown to green due to its location, and that the development project of a private park on park and town boundaries significantly lowered the view ratio. This implies a large degree of damage to the landscape by development projects provided protection of the view as a natural landscape is of value. Chudong Park also saw its view ratio of views from downtown to the hills green area of Chudong Park was much lower than that of Jikdong Park. And it was confirmed that the ratio of view changes due to development projects was small compared to that of Jikdong Park. In other words, although Jikdong Park and Chu-dong Park were developed in a similar scale in terms of the ratio of views, they were subject to significant damage due to their location characteristics. It is also meaningful to note that the degree of change in the landscape resulting from development projects that could not be found in the assessment or review of the existing Landscape Impact. As private parks are introduced in the urban green belt, apartment development is being pushed for at the edge of the green belt. This study is meaningful in that it is derived based on the calculation that the survey results are derived based on the changes in the views on green areas that urban residents may experience as the private park project is carried out, and it should be introduced based on the calculation of the private parks.

• Spatial Information Research
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• v.19 no.1
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• pp.21-28
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• 2011

With the recent overcrowding of metropolitan cities and people's increasing interest in housing environment, there are frequent disputes occurring over the right to daylight. In order to determine whether daylight has been encroached accurately. we need to consider the daylight change by the effect of the geographical features of the surrounding areas but most of the previous relevant studies overlooked this consideration. Thus, in order to determine the encroachment of daylight accurately, this study analyzed the change in the duration of daylight according to geographical features by applying the Hemispherical Viewshed Algorithm to Busan Metropolitan City. According to the results of the analysis, the minimum and average duration of daylight decreased with an increase of altitude by 50m. Second, according to the time bound designated by law, up to 78.6% of the area was influenced by the duration of daylight. Third, the geographical features of the surrounding areas had a significant effect on the duration of daylight. Accordingly, in order to analyze the right to daylight accurately, it is essential to consider the geographical features of the surrounding areas. Furthermore, the Hemispherical Viewshed Algorithm used in this study and the visible area of the sky obtained from the algorithm are considered helpful to analyze the influence of the geographical features of surrounding areas on the legal duration of daylight before analyzing the practical right to daylight.