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

• Journal of the Korean Association of Geographic Information Studies
• /
• v.15 no.1
• /
• pp.197-210
• /
• 2012

The KOrea Multi-Purpose SATellite(KOMPSAT)-2 has a capability to provide a cross-track stereo imagery using two different orbits for generating various spatial information. However, in order to fully realize the potential of the KOMPSAT-2 stereo imagery in terms of mapping, various tests are necessary. The purpose of this study is to evaluate the possibility of mapping using the KOMPSAT-2 stereo imagery. For this, digital plotting was conducted based on the stereoscopic images. Also the Digital Elevation Model(DEM) and an ortho-image were generated using digital plotting results. An accuracy of digital plotting, DEM, and ortho-image were evaluated by comparing with the existing data. Consequently, we found that horizontal and vertical error of the modeling results based on the Rational Polynomial Coefficient(RPC) was less than 1.5 meters compared with the Global Positioning System(GPS) survey results. The maximum difference of vertical direction between the plotted results in this study and the existing digital map on the scale of 1/5,000 was more than 5 meters according as the topographical characteristics. Although there were some irregular parallax on the images, we realized that it was possible to interpret and plot at least seventy percent of the layer which was required the digital map on the scale of 1/5,000. Also an accuracy of DEM, which was generated based on the digital plotting, was compared with the existing LiDAR DEM. We found that the ortho-images, which were generated using the extracted DEM in this study, sufficiently satisfied with the requirement of the geometric accuracy for an ortho-image map on the scale of 1/5,000.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.12
• /
• pp.660-668
• /
• 2018

The main object of this study was to find a way to operate the marker for simulating a virtual construction using a MR(mixed reality) device. The secondary object was to find a way to extract the form-data from BIM data, and to represent the virtual object by the MR device. A tiny error of scale causes large errors of length because the architectural objects are very large. The scale was affected by the way that the camera of the MR device recognizes the marker. The method of installing and operating the marker causes length errors in the virtual object in the MR system. The experimental results showed that the error factor of the Virtual object's length was 0.47%. In addition, the distance between the markers can be decided through the results of an experiment for the multi-marker tracking system. The minimum distance between markers should be more than 5 m, and the error of length was approximately 23mm. If the represented virtual object must be less than 20mm in error, the particular mark should be installed within a 5 m radius of it. Based on this research, it is expected that utilization of the MR device will increase for the application of virtual construction simulations to construction sites.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.1737-1741
• /
• 2008

하천 개수나 치수를 위한 기초 연구의 일환으로 수치모형을 이용한 검증 및 예측 과정이 요구되어 왔고, 고전적인 수치모의 방법으로 결과 산출이 용이한 1차원 모형을 적용시켜 왔다. 1차원 모형의 경우 모의영역을 쉽게 넓힐 수 있고, 입력 자료가 간단하다는 장점이 있지만, 수직적이고 수평적인 흐름특성 변화 및 난류 구조를 보이는 3차원적인 자연하천 흐름을 종방향의 1차원적인 모의 결과를 이용하여 평가한다는 점에서 비현실적이다. 하천을 가로질러 교각이나 보와 같은 구조물이 위치하고 있거나, 좌우 비대칭적인 형상의 수로를 모의할 경우 흐름특성의 공간적인 분포는 단순한 단면 평균적인 개념으로는 설명되기 힘들다. 최근에야 비로소 수공학 관련 실무자들에 의해서 최소한 2차원 수치모형을 기본적인 평가법으로 도입해야 한다는 분위기가 감지되고 있으며, 일반적으로 한강과 같은 대하천을 모의할 경우, 대다수의 실무자들과 연구자들이 축척을 문제 삼아 수로 내부에 위치한 교각을 생략하여 2차원 모의를 수행하기도 한다. 따라서 본 연구에서는 수로 내부에 위치한 교각을 2차원 모의하는 방법에 대한 비교 평가를 수행하고자 한다. 동일한 격자를 이용하여 교각을 고려하지 않았을 경우와 교각 형상을 모의 영역에서 삭제하여 경계처리를 하였을 경우, 마지막으로 교각이 위치하고 있는 영역에 항력을 적용하였을 경우에 대해서 비교 평가한다. 이를 위하여 2차원 천수방정식을 흐름방정식으로 하는 유한요소모형을 구축하였으며, 모형의 검증을 위해 교각이 수로에 위치할 경우에 대한 실내 실험 자료와 비교한다. 또한 검증된 모형을 이용하여 교각이 포함된 한강의 일부 구간을 선정하여, 교각 모의 방법에 대한 비교 평가를 수행한다. 본 연구에서 구축된 자료 및 제시된 수치모형은 하천복원, 치수관리 측면에서 매우 유용하게 사용될 것으로 기대된다.

• Journal of Korean Society for Geospatial Information Science
• /
• v.19 no.4
• /
• pp.101-108
• /
• 2011

Construction of the Jangbogo antarctic station was planned, and it requires detailed information on topography of the area around the station. The purpose of this research is to generate the topographic map to construct the Jangbogo antarctic station using the satellite image. To do this, surveying and pre-test of equipment were conducted. In addition, for sensor modeling of the GeoEye-1 satellite image, RPC-bias correction was done, and it showed that at least two control points are required. In generating the map, a 1/2,500 scale was deemed suitable in consideration of resolution of the image and the fact that supplementary topographic surveying would be impossible. In order to provide detailed information on the topography around the Jangbogo station, the digital elevation model based on image matching was created, and compared with GPS-RTK data, accuracy of vertical location about 0.6m was exhibited.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.29 no.6
• /
• pp.631-639
• /
• 2011

There are problems in using existing fisheries maps, because of deterioration of paper maps, as well as various coordinate systems. In this study, accuracy of fishery maps in World Geodetic System are evaluated. Materials on fishery rights in the Jeollanam-do Province, a study area, used many kind of coordinate systems. During digitization, these coordinate systems have been converted and unified in one World Geodetic System, and one projection origin. In this research, the accuracy of the products of digitization is verified using DGPS surveying. The RMSEs are minimum of 4.62m(at the Younggwang Seas) to maximum of 17.47m(at the Jangheung Seas), and average of 11.97m. The results shows that the digitized fishery maps meet the accuracy standard of 1/25,000 digital topographic maps.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.30 no.5
• /
• pp.435-444
• /
• 2012

Although the multi-scale map database should be constructed for the web map services and location-based services, much part of generation process is based on the manual editing. In this study, the map generalization methodology for automatic construction of multi-scale database from the primary data is proposed. Moreover, the generalization methodology is applied to the real map data and the prototype of multi-scale map dataset is generated. Among the generalization operators, selection/elimination, simplification and amalgamation/aggregation is applied in organized manner. The algorithm and parameters for generalization is determined experimentally considering T$\ddot{o}$pfer's radical law, minimum drawable object of map and visual aspect. The target scale level is five(1:1,000, 1:5,000, 1:25,000, 1:100,000, 1:500,000) and for the target data, new address data and digital topographic map is used.

• Journal of Korean Society for Geospatial Information Science
• /
• v.24 no.4
• /
• pp.83-88
• /
• 2016

The use of consistent coastlines is an important element for the systematic management of maritime boundaries and the interests of local governments. The Hydrographic and Oceanographic Agency conducted a preliminary survey for consistent coastline production, since 2001. As a result, the length of coastline was different by year. Because of the lack of systematic management, the use of incorrect data, etc. We also changed the coastline on the sea chart to show on a digital map for realization of terrain expression method. However, there was a variation in shoreline length due to various surveying techniques and shoreline extraction methods. In this paper, the characteristics of Jeju-do coastline were analysed by using a modified divider method of fractal dimension. The accuracy of the vectorization was determined by converting the actual distance in the Public Survey Amendment for proper divider use. With 1:5,000 and 1:25,000 digital maps of Jeju-si and Seogwipo-si each fractal dimensions were calculated. Jeju-si=1.14 and Seogwipo-si=1.12 in 1: 5,000. Jeju-si=1.13 and Seogwipo-si=1.10 in 1: 25,000. Calculated fractal dimension were correlated to data from digital maps. It was considered that complexity and scale of coastlines affected. In the future coastline length statistics and minimum ratio of calculated coastline length to original length need to be determined for consistency of coastline length statistics.

• Applied Chemistry for Engineering
• /
• v.17 no.2
• /
• pp.210-216
• /
• 2006

The concentrations of 16 priority PAHs (US EPA standard) were analyzed in the surface sediments obtained from 23 sampling sites near Kwangyang Bay in Korea. There was a local variability in the total PAHs ranged from 0.01 to 171.39 mg/kg, with a mean value of $8.13{\pm}24.8mg/kg$. The major pollution sources of PAHs near Kwanyang Bay were Taeindo, Sueo stream and Wallae stream, whose concentrations were 114.81, 38.37 mg/kg and 19.05 mg/kg, respectively. It showed that PAHs concentrations were increased with the decrease of particle size and with the increase of organic carbon contents in three fractioned sediments. From the analysis of PAHs source using LMW/HMW, Phe/Ant, and Fla/Pyr, pyrolysis by-products were mostly showed in Kwangyang Bay and some place showed the mixure of pyrolysis by-products, and crude oil by-products. Besides, the toxic effects assessment on benthic ecosystem for three major pollution sources showed that the PAHs concentration of Taindo which was mainly accumulated with carcinogenic PAHs exceeds ERM value and the PAHs of Sueo and Wallae streams are the degree of ERL value.

• Journal of Digital Convergence
• /
• v.14 no.5
• /
• pp.325-331
• /
• 2016

In driving at evening or night, we are not able to recognize the speed bump and so stop suddenly. It could result in accidents. And also, we have a restriction of street light installation in farm road because it could be harmful to the crops and driver could not recognize the walking people. It needs to develop the speed bump with light and streetlight to be non harmful to the crops. So, we develop both the speed bump and streetlight with LED which could be non harmful to the crops and be increased recognition of walking people in farm road. For LED lighting power, we use the solar cells, and piezoelectric elements. It has automatic on/off according to power saving rates without illumination sensor. Minimization of circuit elements and design of minimum resisters and low power LED was used for power saving in assuring 3-days.