• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.6
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• pp.509-516
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• 2017

In cadastral surveying, there are problems that no area error is allowed where numerical surveying is carried out, and allowable area error is specified irrespective of parcel shape where graphic surveying is carried out. In this research, we derived a general formula of parcel area error necessary for grasping these two problems. The calculations using the derived formula showed that where the coordinate error of the boundary point is set to 5cm+10ppm practically, then even a small parcel of $100 m^2$ includes non-negligible area error of $0.71m^2$. And, it is found that the area error specified by the current egulation is based on a rectangular parcel of 1:5 aspect ratio. These results show that the area error of polygon parcel can be determined by a single formula by specifying the coordinate error of the boundary points, and can be used to revise the current regulations that can be applied uniformly regardless of surveying methods.

• Journal of Cadastre & Land InformatiX
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• v.52 no.1
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• pp.5-16
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• 2022

Based on the general formula for the area error of a polygon and rectangular parcel, the constant term 0.026² × M (scale denominator) of the area error calculation formula prescribed by the Enforcement Decree was analyzed. As a result, it is found that the formula appropriately reflects the characteristics of the graphical surveying as a typical rectangular parcel model, but quantitatively allows a relatively large area error. In addition, it is found that, even if the area is the same, 50% more area error than a square parcel could be calculated depending on the shape of the parcel, and that the allowable area error should be different when dividing a parcel. Based on the analysis, furthermore, this study shows a solution that can solve the problems at once from the point of cadastral surveying. These are, the problem of reflecting the accuracy of the surveying, the problem of reflecting the size and shape of the parcel, and the problem whether a single area error formula can be used without having to distinguish between graphical and numerical surveyings. The new formula that solves these problems will bring about improvements in many related factors and promote the development of digital cadastral system.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.104-104
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• 2016

소규모 하천에서의 평수기 유량 측정은 일반적으로 지점식 초음파 유속계, 프로펠러 유속계 등을 활용해 도섭법으로 측정된 유속 측정성과를 기반하여 유속-면적법으로 산정된다. 유속-면적법으로 측정된 유량 측정 성과는 횡방향 측선의 수, 수심방향 측점의 수, 측정 시간, 수심 등 제반 측정 인자에 의해 영향을 받고 유량 불확도는 각 인자 별 오차에 영향을 받는다. ISO 748 (2007)과 ISO 1088 (2007)은 유속-면적법 적용방법, 현장 측정 가이드라인, 불확도 인자 별 적용 요건에 따른 오차, 최종 유량 불확도 산정 기법을 제시하였다. 따라서, 국내외 유량조사 기관에서는 유속면적법을 적용할 경우, ISO에서 제시된 인자 별 오차 및 유량 불확도 산정 기법을 기반으로 유량 불확도를 산정해왔다. ISO 748과 1088은 다양한 규모의 실제 하천에서 관측된 자료를 기반으로 횡방향 측선 수, 수심방향 측점 수 (2점법, 3점법 등), 측정 시간 등과 관련된 인자 별 오차를 표로 상세하게 제시하였고 실무에서는 별도 추가 검증없이 사용해 왔다. 그러나, ISO에서 유속-면적법 유량 측정 불확도를 평가하기 위해 사용된 측정자료는 유량을 제어하기 힘들고 유속 측정 상황이 유출 조건 별로 상이한 현장 자료를 기반으로 하였고, 상대적으로 정확도가 낮은 프로펠러유속계를 기반으로 1960년대에 관측된 자료들을 주로 활용하여 도출되었다. 따라서, 본 연구에서는 기존 ISO에서 제시한 유속-면적법에 필요한 인자들의 오차를 정밀 실규모 실험을 통해 재산정하여 기존 ISO 748과 1088에서 제시한 인자별 오차의 적정성을 검증하고자 하였다. 이를 위해 흐름을 안정적으로 통제할 수 있는 건설기술연구원 안동 하천실험센터의 완경사수로(A2)에서 정상상태의 폭 7m, 수심 1m, 유속 약 1m/s의 흐름을 유지한 후, 유속 측정 정확도가 우수한 micro-ADV를 활용하여 공간적으로 매우 정밀하게 유속을 측정하고, 수심은 Total Station을 기반으로 흐름 발생 전에 정밀 측정하였다. 오차 분석 결과, ISO 규정에서 제시한 오차와 본 실험의 결과로 도출된 인자들의 오차는 상당한 차이를 보였다. 따라서, 본 연구 결과로 도출된 유속-면적법의 인자 별 오차는 실험이 수행된 소하천 규모의 하천에서 도섭법으로 산정된 유량의 불확도를 평가할 경우에 활용될 것으로 기대된다.

• Spatial Information Research
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• v.18 no.4
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• pp.43-53
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• 2010

A dam is effective in stable supply of water required in daily life and reduction of damage from floods. hut a lot of land or houses arc submerged due to the construction of a darn heavily affecting environment in surrounding areas. In order to improve and support daily life environment. surrounding a dam, many projects have been conducted. and the study has focused on analyzing bow to calculate error characteristics of scale effect for submerged area by using GIS spatial overlay. First, as a result of areal error in submerged area by scale based on a 1/3,000 digital topographic map, it was found that the 1/5,000 digital topographic map is 9.5 times, 9.0 times and 10.5 times more accurate than the 1/25,000 digital topographic map, respectively, in the total of areal error, standard error and areal error for submerged area. Second, as a result of analysis on areal error in areas surrounding a dam, it has been found that Jinan-eup in Jinan-gun registered the largest difference in area within 2km and 2~5km catchment area by recording 13.8 times and 20.6 times, respectively, in the 1/5,000 digital topographic map compared to the 1/25,000 digital topographic map. In addition, in areas out of catchment area within 2km, the area of occupation was very small, so there were no characteristics in error. The out of catchment area, Nami-myeon in Geumsan-gun recorded the largest errors of 31.8 times. Finally, it was found that the ratio of the total areal error in area surrounding a dam, standard error and the total areal error in the entire area using 1,5000 digital topographic map is 7.4 times, 11.8 times and 7.4 times more accurate than the 1/25,000 digital topographic map.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5D
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• pp.523-531
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• 2010

A dam is effective in stable supply of water required in daily life and reduced damage from floods, but there are problems as a lot of land or houses are submerged. Therefore many projects have been conducted in order to improve and support daily life environment surrounding a dam. This study has focused on analyzing how to calculate support working expenses for Dam area by using GIS spatial overlay in addition to effects of scale of a topographic map and reached the following conclusion. First, as a result of areal error in submerged area by scale based on a 1/3,000 digital topographic map, it has been found that a 1/5,000 digital topographic map is 9.5 times more accurate than a 1/25,000 digital topographic map in the total of areal error. Second, as a result of areal error in area surrounding a dam, it has been found that a 1/5,000 digital topographic map is 7.4 times more accurate than a 1/25,000 digital topographic map in the total of areal error. Third, as a result of error of support expense for submerged area, it has been found that a 1/5,000 digital topographic is 15.9 times, 14.7 times and 15.9 times more effective than a 1/25,000 digital topographic map in terms of the total error of support expense, standard error and the total support expense error on the entire project costs in submerged area. In addition, as a result of analysis on error of support expense for area surrounding a dam, it has been found that a 1/5,000 digital topographic map was 10.7 times, 9.6 times and 10.6 times more effective, respectively, in the total error of support expense, standard error and the total error of support expense for the entire project costs in area surrounding a dam compared to a 1/25,000 digital topographic map. Lastly, as a result of error of the entire project costs for area surrounding a dam, it has been found that a 1/5,000 digital topographic map was 1.4 times, 1.3 times and 1.4 times more effective, respectively, in the total error of support expense, standard error and the total error of the entire project costs compared to a 1/25,000 digital topographic map, but it was not much different from the result of calculating areal error in submerged area or area surrounding a dam because population item didn't consider areal concept.

• Journal of Korea Water Resources Association
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• v.35 no.5
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• pp.575-581
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• 2002

This study evaluates the variation of estimation error of area-average rainfall due to rainfall seasonality. Both the cases considering and not considering the spatial correlation are compared to derive the characteristics of estimation error. Similar cases with different accumulation time without considering the rainfall seasonality are also investigated. This study was applied to the Geum-river basin with total 28 rain gauge measurements haying more than 30 years of daily rainfall measurements. As results of the study we found that: (1) The absolute estimation error of monthly area-average rainfall show strong seasonality like the total rainfall amount. However, the relative estimation error normalized by its mean was estimated to have similar values about 5 to 8% except January and December. (2) The relative estimation error of annual area-average rainfall estimated was found to have the estimation error about 3% of its annual mean. (3) However, the relative estimation error normalized by the standard deviation remains almost the same for both monthly and annual rainfall amounts, which was estimated about 11% of its standard deviation. (4) Finally, the estimation error without considering the spatial correlation was found to become almost twice the estimation error with considering the spatial correlation.

• Journal of Wetlands Research
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• v.16 no.1
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• pp.103-112
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• 2014

Area average rainfall estimation is important to determine the exact amount of the available water resources and the essential input data for rainfall-runoff analysis. Like that, the necessary criterion for accurate area average rainfall estimate is the uniform spatial distribution of raingauge network. In this study, we suggest the spatial distribution evaluation methodology of raingauge network to estimate better area average rainfall and after the suggested method is applied to Han River and Geum River basin. The spatial distribution of rainfall network can be quantified by the nearest neighbor index. In order to evaluate the effects of the spatial distribution of rainfall network by each basin, area average rainfall was estimated by arithmetic mean method, the Thiessen's weighting method and estimation theory for 2013's rainfall event, and evaluated the involved errors by each cases. As a result, it can be found that the estimation error at the best basin of spatial distribution was lower than the worst basin of spatial distribution.

• Journal of Korea Water Resources Association
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• v.35 no.3
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• pp.307-319
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• 2002

This study used the WGR model to generate the rainfall input and the modified Clark method to estimate the runoff with the aim of investigating how the errors from the areal average rainfall propagates to runoff estimates. This was done for several cases of raingauge density and also by considering several storm directions. Summarizing the study results are as follows. (1) Rainfall and runoff errors decrease exponentially as the raingauge density increases. However, the error stagnates after a threshold density of raingauges. (2) Rainfall errors more affect to runoff estimates when the density of raingauges is relatively low. Generally, the ratio between estimation errors of rainfall and runoff volumes was found much less than one, which indicates that there is a smoothing effect of the basin. However, the ratio between estimation errors of rainfall to peak flow becomes greater than one to indicate the amplification of rainfall effect to peak flow. (3) For the study basin in this studs no significant effect of storm direction could be found. However, the runoff error becomes higher when the storm and drainage directions are identical. Also, the error was found higher for the peak flow than for the overall runoff hydrograph.

• Journal of Korea Water Resources Association
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• v.41 no.5
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• pp.545-558
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• 2008

This study estimated the error involved in the areal average rainfall derived from incomplete radar information due to radar partial coverage of a basin or sub-basin. This study considers the Han-River Basin as an application example for the rainfall observation using the Ganghwa rain radar. Among the total of 20 mid-sized sub-basins of the Han-River Basin evaluated in this study, only five sub-basins are fully covered by the radar and three are totally uncovered. Remaining 12 sub-basins are partially covered by the radar to result in incomplete radar information available. When only partial radar information is available, the sampling error decreases proportional to the size of the radar coverage, which also varies depending on the number of clusters. Conditioned that the total area coverage remains the same, the sampling error decreases as the number of clusters increases. This study estimated the sampling error of the areal average rainfall of partially-covered mid-sized sub-basins of the Han- River Basin, and the results show that the sampling error could be at least several % to maximum tens % depending on the relative coverage area.

• Journal of Korean Society for Geospatial Information Science
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• v.8 no.1 s.15
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• pp.111-120
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• 2000

A cadastral map that is base map on Land Information System is divided by two categories, graphical and digital cadastre. And digital cadastre can be displayed with location coordinates of nodes that depict parcel boundary on digital cadastral records. The transformation of digital cadastral records means that imported text data of node coordinate would be transformed into system data. This study was implemented to search reasons of errors resulted from transformation of graphic data and then to analyze the accuracy in terms of Position and area. For this, checking of software used in Geo-Spatial Information System was implemented at first and it was found that the accuracy is up by using double precision in coordinate transformation. On the position accuracy the errors at nodes was erased during making topology and the errors did not effect other nodes. On the area may the area errors because of being in error limit of allowable area had no problems in using of system.