• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.3
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• pp.213-223
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• 1999

This study provides a improved model of digital basemap production that can efficiently identify and correct the various errors generated in digital map production process. In order to fulfill the requirements that the new model calls for, this study provides a typology of errors by analyzing the errors in digital basemap data. Computer programs for automatic error searching and for checking the correctness of the digital codes in the data have also been developed. Exsiting visual error-checking process has also been analyzed and more systematic process is suggested. As a result, it is found that the improved model of digital basemap production suggested in this study contributes to improving the quality of the digital map database by providing a systematic method for efficient error-searching and correction of digital map data.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.293-293
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• 2018

관망내 흐름의 수치 모델링은 도시 침수 분석, 하수도 관의 손상 탐지 또는 하수도 시스템 설계와 같은 넓은 분야에 적용되는 매우 중요한 문제 중 하나이다. 관망내 흐름상태는 자유수표면이 존재하는 개수로 흐름과 자유수표면이 관내에 존재하지 않는 관수로 흐름, 그리고 개수로 흐름과 관수로 흐름의 경계지점에 혼합흐름상태가 존재한다. 개수로 흐름과 관수로 흐름의 해석을 위해서는 일반적으로 다른 지배방정식의 적용이 필요하며 이는 관망내 흐름해석을 어렵게 만드는 원인 중 하나가 된다. 이러한 어려움을 극복하기 위해서 관망의 흐름해석에는 일반적으로 Preissmann slot 모델이 널리 사용되고 있다. 그러나 그럼에도 불구하고, Preissmann slot 모델의 수치해석 시 수치진동으로 인한 수치적 불안정이 발생하기 쉬우며, 특히 개수로 흐름에서 관수로 흐름으로 넘어가는 혼합흐름상태에서 이러한 수치진동이 쉽게 발생하는 것으로 알려져 있다. 이러한 수치진동은 수치적 불안정성을 유발할 뿐만 아니라, 해의 정확성을 크게 저하시킬 수 있다. 본 연구에서는 이러한 문제를 극복하기 위해 Preissmann slot 모델의 새로운 수치기법을 제안하였다. Approximate Reimann flux solver와 Centred flux solver를 결합하여 하이브리드 해석기법을 개발하였다. 수지진동 발생하기 쉬운 실험들의 모의를 통하여 수치기법의 성능을 검증하였다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.1
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• pp.21-28
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• 2011

In the existing digital map of the Ver.1.0, it is impossible to make a small scale digital map, which is under the 1/5000 scale map, by using the 1/1000 digital map which is the most large scale one. Because of this reason, the existing digital maps are produced into a 1/1000 and a 1/5000 map by means of two different scale aerial photos. The next generation digital map should be successively related to a small scale digital map based on the most large scale digital one. This is so important from the aspects of data share and the consecutive renewal. Ever since the development of the digital map of the Ver. 2.0, the possibility of making a multi-scale consecutive digital map has been presented and the related research has been done again. The most basic thing in the multi-scale digital maps is to decide the criteria of the generalization between the two scales. In this study, I try to formulate the criteria of the generalization required to make the 1/5000 digital map by using the 111000 digital one. In addition, I by to explore the application possibility of the consecutive renewal by carrying out auto-generalization.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.439-455
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• 2012

Coupled wave induced current modeling system(WIC) was developed from combining with the nearshore spectral wave model, SWAN, the wave induced force model, WIF, and the flow model, EFDC. The reasonable results were obtained from WIC modeling system. The ratio of the wave height calculated with respect to refraction and diffraction effects over submerged spherical shoal was occurred approximately 1~5 % errors compared to Goda(2000)'s result. The radiation stress suggested by Longuet-Higgins and Stewart(1960), the stresses due to rollers in breaking waves proposed by Dally and Osiecki(1994), and Kim(2004)'s new spreading approach instead of the previous lateral mixing approach were added to calculate wave induced force. The results of the WIC modeling system show good agreement with Nishimura et al.(1985)'s laboratory measurements and better than Kim(2004)'s 2 dimensional depth averaged numerical computations for a plane beach with detached breakwater. The present flow field computed agrees reasonably well with the measured flow field. The relative merit of WIF model in WIC modeling system is unconditional stable for time increment.

• Journal of Navigation and Port Research
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• v.29 no.3 s.99
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• pp.269-274
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• 2005

Geodetic surveying using precise GPS equipment are used without analysis with a statistical verification of GPS observed value and it was preformed by necessity to integration projection of digital topographic map and nautical Chart for integration geographic information system construction. The purpose of this study proposes method that improve accuracy of GPS observed value and direction that integrally manage digital topographic map and electronic nautical chart in analyzing the boundary line error between digital topographic map and nautical Chart. For improvement of the precision of GPS observed value, the author studied precision-analysis of GPS observed value by geometric strength and variance factor in 3 control points used in GPS network adjustment. And like this, produce EDM measurement using this GPS observation results and compare the whole boundary point error when set digital topographic map and nautical chart by these boundary.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.43-43
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• 2011

최근 컴퓨터 기술의 발전으로 수심방향으로 완전한 운동방정식인 Navier-Stokes 방정식을 이용하는 3차원 수치모형에 의한 연구가 기초과학 분야인 수학에서부터 공학은 물론 의학 분야까지 광범위하게 진행되고 있다. 3차원 수치모형을 이용한 연구는 이론적으로 매우 우수하긴 하나 정확도 높은 결과를 얻기 위해서는 매우 조밀한 격자를 필요로 하기 때문에 아직까지 막대한 계산시간이 필요하다는 단점이 있으나 근래의 컴퓨터 기술이 엄청난 속도로 발전하고 있는 점을 감안할 때 적용 가능성은 계속 높아지고 있다. 이러한 흐름에 따라 해안공학 분야에서도 3차원 수치모형을 이용한 다양한 연구가 시도되고 있다. 복잡한 해안구조물로 인한 파랑변형 및 구조물의 안전성 등을 검토할 때 기존의 평면 2차원 수치모형이나 연직 2차원 수치모형으로는 재현이 힘들어 상대적으로 수치모형을 활용한 연구의 효용성이 낮았던 것에 비해 3차원 수치모형을 활용할 경우 복잡한 지형 및 구조물의 형상을 재현할 수 있기 때문에 좀 더 유용하게 사용될 수 있다. 한편, 파랑변형을 다루는 수치모형실험을 수행할 때 외부조파를 사용할 경우 구조물이나 지형에 의해 반사되어 나온 파랑이 조파지점에 도달할 때 실험영역으로 재 반사되는 문제가 발생한다. 이를 해결하기 위해 내부조파기법의 개발에 대한 연구가 필수적이었으며, 2차원 수치모형을 중심으로 그 연구가 매우 활발하게 진행되어 왔으나 Navier-Stokes 방정식 모형의 경우 상대적으로 연구가 미흡하였다. 본 연구에서는 3차원 Navier-Stokes 방정식 모형에서 내부조파기법을 도입하여 목표 파랑을 조파하였다. 수치모형은 Navier-Stokes 방정식을 엇갈림 격자체계에서 계산하는 유한차분모형으로 자유수면 추적에는 2차 정확도의 VOF(volume-of-fluid) 기법을 사용한다. 수치모형실험 결과를 일정한 수심을 전파하는 정현파의 해석해와 비교하였으며, 수치모형실험 결과가 비교적 정확하게 목표 파랑을 조파할 수 있음을 검증하였다.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.3
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• pp.57-64
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• 2009

Field surveys for the digital map being constructed is being conducted using various work guide books based on the digital mapping internal rule. However, a modification of a rule used for paper map construction is being used for the digital mapping rule, which is causing many problems with the quality of the digital map. Therefore, to construct a high-quality digital map, general standards related to conducting field surveys need to be reviewed, and it's extremely important to construct an accurate digital map based on this. Accordingly, in this study, problems related to conducting field surveys for the construction of the digital map are analyzed in order to establish more suitable field survey standards for constructing an accurate digital map. To this end, work regulations related to construction of a digital map were analyzed, and attribute and field survey data were compared to those of a previously-constructed digital map for analysis. By reflecting opinions of field surveyors and related experts to the results of the analysis, more suitable field survey standards for constructing the digital map were presented.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.3
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• pp.233-244
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• 2004

Recently, digital image is increasing greatly practical use degree in several industry fields including construction. And interest about 3D digital image that can express practical object realistically is augmented greatly. In this study, developed 3D digital image generation system based on digital photogrammetry and created 3D digital image fer object. And, wished to verify of 3D digital image through comparative analysis with processing result by digital photogrammetry system been using much the latest for acquisition of 3D information. Also, wished to apply to surface information acquisition about rock slope and execute investigation about discontinuity of joint etc. As the result, could created 3D digital image fur object using the 3D digital image generation system developing in this study, and acquire surface information about rock slope efficiently.

• Tunnel and Underground Space
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• v.14 no.4
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• pp.287-294
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• 2004

To predict the temperature distribution around a underground rock storage cavern, two- and three- dimensional numerical analysis using FLAC was conducted. The effects of groundwater and latent heat on thermal properties were considered in numerical calculation. The temperature estimated by FLAC are compared with the temperature measured for 5-year operation at Gonjiam storage cavern. Estimated and measured temperatures showed great discrepancy when thermal properties from laboratory tests were used and showed good agreement when the effects from 20% of volumetric water fraction and latent heat were considered. However, the discrepancy still increased with operation time due to the heat flow from ground surface. Three-dimensional numerical models were established to closely approximate the boundary condition of the test site, and numerical results better agreement when groundwater and latent heat effects were considered.

• Journal of Korean Society for Geospatial Information Science
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• v.5 no.2 s.10
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• pp.65-75
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• 1997

Nowadays, digital map plays a role as a container of spatial database.'there have been many researches concerning the improvements of the digital map accuracy. From the user's viewpoint, however, the quality level of digital nap is as important as its accuracy, because fitness-for-use is considered the most important factor to the users. This study aims to find the methodology for determining the grade nか digital map. To accomplish this, we propose two major stages. First, weight factors of the layers are given according to the importance of the functions which must be considered in digital map generation. Scond, weight factors of the components to evaluate the accuracy of the digital map are presented By scoring the components and by summing the scores, the method for determining fitness-for-use is developed.