• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.1
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• pp.1-11
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• 2018

Mapping accurate spatial information is important for constructing three-dimensional (3D) spatial models and managing artificial facilities, and, especially, mapping road centerlines is necessary for constructing accurate road maps. This research developed a semi-automatic methodology for mapping road centerlines using the MMS(Mobile Mapping System) LiDAR(Light Detection And Ranging) point cloud as follows. First, the intensity image was generated from the given MMS LiDAR data through the interpolation method. Next, the line segments were extracted from the intensity image through the edge detection technique. Finally, the road centerline segments were manually selected among the extracted line segments. The statistical results showed that the generated road centerlines had 0.065 m overall accuracy but had some errors in the areas near road signs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4D
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• pp.561-567
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• 2008

In this study, shoreline change was analyzed by RTK-GPS and advanced airborne LiDAR survey. For extraction of coastline, first of all, tide correction was conducted at all RTK-GPS points through the comparing with the corresponding tidal height, and cross section providing coastline was produced using Autocad Civil3D program. Comparing with two results of RTK-GPS (first, 29 Aug 2007; second, 6 Oct 2007) surveys, coastline of the first result had been decreased about 21m compare with that of the second. And it was also demonstrated that the length of coastline by the first RTK-GPS was 15m shorter than that by the airborne LiDAR survey (Dec. 2006). In addition, we recoquized that the erosion appeared in the top right-hand (dock area); the sediment in the bottom left-hand (Chosun beach area) of the Haeundae beach. As a result, therefore, it was learned that artificial sand filling for beach open and natural effects such as a typhoon, current drift, wind direction gave cause for area changes and coastline.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5D
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• pp.655-662
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• 2009

The monitoring for analyzing coastline variations throughout many years is conducted in this study. Haeundae Beach is selected as a test area. We have collected RTK-GPS survey data, airborne LiDAR survey data from Sept. 2008 to 2005. We've done airborne LiDAR survey 2009 to 2006 and we would analyze coastline changes time series through interactive comparison analysis. The mean coastline distance of Haeundae shore is 1,347m (RTK-GPS) by airborne LiDAR survey (2 times). Coastline distance is decreased approximately 4.5% than mean distance in the November survey of 2008. We know right and left sides of the coastline are eroded and the center section shows us the littoral deposit of 3~7m toward sea. It turns out that the sand both sides is transported to the center section by a wave and tide and we know the coastline distance is getting smaller but the coastline width is getting longer like 2~7m.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.2 s.40
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• pp.59-66
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• 2007

The digital working environment and its related technology have been rapidly expanding. In the surveying field, we have changed from using optical film cameras and plotters to digital cameras, multi sensors like GPS/INS etc,. The old analog work flow is replaced by a new digital work flow. Accurate data of the land is used in various fields, efficient utilization and management of land, urban planning, disaster and environment management. It is important because it is an essential infrastructure. For this study, LiDAR surveying was used to get points clouds in the study area. It has a high vegetation penetrating advantage and we used a digital process from planning to the final products. Contour lines were made from LiDAR data and compared with national digital base maps (scale 1/1,000 and 1/5,000). As a result, the accuracy and the economical efficiency were evaluated. The accuracy of LiDAR contour data was average $0.089m{\pm}0.062\;m$ and showed high ground detail in complex areas. Compared with 1/1,000 scale contour line production when surveying an area over $100\;km^2$, approximately 48% of the cost was reduced. Therefore we prepose LiDAR surveying as an alternative to modify and update national base maps.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.394-399
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• 2003

도시 지역의 대부분을 차지하는 건물에 대한 3차원 정보는 도로, 교통 등의 시설물관리시스템 구축, 도로계획, 택지개발, 도시계획 등 여러 분야에 필요하다. 현재 항공사진, 고해상도 위성영상, LiDAR 자료, 수치사진측량 시스템 등의 보급과 분석 알고리즘의 발전으로 인하여 도시지역 건물 3차원 모델링에 대한 연구가 활발히 진행되고 있는데, 그 중에서 정밀한 DSM 취득이 가능한 LiDAR 자료가 도시지역 건물 3차원 모델링에 가장 유망한 자료이다. 그러나 LiDAR 자료만을 이용할 경우에는 선형화 과정 등의 수작업이 많이 들어가고, 주관적인 재구성과정이 들어가야 하는 문제점이 있다. 따라서 본 연구에서는 수치지도를 LiDAR 자료와 같이 이용하여 건물 3차원 모델링시 작업자의 수동적인 과정을 단축하였다. 항공사진과 해석도화기를 이용한 정확도 평가 결과 1:5,000 수치지도 정확도 규정을 만족하는 도시지역 건물 3차원 모델링이 가능하였고, 비교적 자동화된 공정을 이루었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.466-466
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• 2012

하천의 하구에서는 해수의 흐름에 따른 연안토사의 이동과 하천유황에 따른 상류에서의 토사량에 따라 하상이 변화한다. 특히 하구부에서의 퇴적토사 증가는 하천의 수질변화와 어도단절 등으로 인해 하천환경에 악영향을 끼칠 수 있는 하구폐쇄를 발생시킬 수 있어 이에 따른 모니터링이 필요하다. 본 연구에서는 동해안으로 유출되는 지방 1급 하천인 가곡천과 호산천을 대상으로 하구부 퇴적토사의 변화를 모니터링 하였다. 하상변화의 모니터링은 최신장비인 지상 LiDAR를 이용하여 다시기로 스캔한 지상 LiDAR 측정자료를 활용하여 퇴적량을 산출하고 퇴적과 침식의 변화양상을 분석하였다. 분석결과 퇴적지점과 침식지점 및 이에 대한 체적량 변화를 정밀하게 확인할 수 있었다. 지상 LiDAR를 활용한 하상변화 분석기법은 정밀한 퇴적량 추이를 빠르게 관찰할 수 있어 하구지역 뿐만 아니라 하천 전반에서의 하상변화를 조사하는 데에 있어 활용도가 높을 것으로 판단된다.

• Korean Journal of Remote Sensing
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• v.26 no.6
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• pp.681-691
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• 2010

LiDAR waveform decomposition plays an important role in LiDAR data processing since the resulting decomposed components are assumed to represent reflection surfaces within waveform footprints and the decomposition results ultimately affect the interpretation of LiDAR waveform data. Decomposing the waveform into a mixture of Gaussians involves two related problems; 1) determining the number of Gaussian components in the waveform, and 2) estimating the parameters of each Gaussian component of the mixture. Previous studies estimated the number of components in the mixture before the parameter optimization step, and it tended to suggest a larger number of components than is required due to the inherent noise embedded in the waveform data. In order to tackle these issues, a new LiDAR waveform decomposition algorithm based on the sequential approach has been proposed in this study and applied to the ICESat waveform data. Experimental results indicated that the proposed algorithm utilized a smaller number of components to decompose waveforms, while resulting IMP value is higher than the GLA14 products.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.04a
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• pp.479-484
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• 2003

The renewal of digital map takes much time and the manual process. LiDAR data allows reduction of time, automatic manner, and acquisition of the precise position. So it is used to renew the digital map of 1:5,000 scale. From the accuracy test results using aerial imagery and digitizing, renewal of digital map are feasible in automatic manner to some extent.

• Korean Journal of Remote Sensing
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• v.29 no.1
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• pp.81-94
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• 2013

The Radar altimeter transmits radio signals to the surface, receives the backscattered signals and measures the distance between the airplane and the nadir surface. The measurements of radar altimeter are affected by various factors on the surface below the aircraft. This study performed flight campaigns in June 2012 and acquired raw data from radar altimeter, LiDAR and other sensors. Based on the LiDAR DSM (Digital Surface Model) as a reference data, the characteristics of radar altimeter were analyzed in the respect of range and surface area affecting on the receiving power of the radar altimeter. Consequently, the radar altimeter was strongly affected by the surface area within beam width and reflectivity related to RCS (Radar Cross Section) rather than range.

• Journal of Korean Society for Geospatial Information Science
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• v.13 no.1 s.31
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• pp.19-25
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• 2005

Nowadays, it is possible to construct the DEMs of urban area effectively and economically by LiDAR system. But the data from LiDAR system has form of DSM which is included various objects as trees and buildings. So the preprocess is necessary to extract the DEMs from LiDAR DSMs for particular purpose as effects analysis of man-made objects for flood prediction. As this study is for extracting DEM from LiDAR DSM of urban area, we detected the edges of various objects using edge detecting algorithm of image process. And, we tried mean value filtering, median value filtering and minimum value filtering or detected edges instead of interpolation method which is used in the previous study and could be modified the source data. it could minimize the modification of source data, and the extracting process of DEMs from DSMs could be simplified and automated.