• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.10
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• pp.1416-1426
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• 2021

In the case of a scanning type multi-channel LiDAR sensor, the distance error called a walk error may occur due to a difference in received signal power. This work error causes different distance values to be output for the same object when scanning the surrounding environment based on multiple LiDAR sensors. For minimizing walk error in overlapping regions when scanning all directions using multiple sensors, to calibrate distance for each channels using convolution on external system. Four sensors were placed in the center of 6×6 m environment and scanned around. As a result of applying the proposed filtering method, the distance error could be improved by about 68% from average of 0.5125 m to 0.16 m, and the standard deviation could be improved by about 48% from average of 0.0591 to 0.030675.

• IEMEK Journal of Embedded Systems and Applications
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• v.16 no.3
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• pp.107-111
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• 2021

A 3D point cloud map is an essential elements in various fields, including precise autonomous navigation system. However, generating a 3D point cloud map using a single sensor has limitations due to the price of expensive sensor. In order to solve this problem, we propose a precise 3D mapping system using low-cost sensor fusion. Generating a point cloud map requires the process of estimating the current position and attitude, and describing the surrounding environment. In this paper, we utilized a commercial visual-inertial odometry sensor to estimate the current position and attitude states. Based on the state value, the 2D LiDAR measurement values describe the surrounding environment to create a point cloud map. To analyze the performance of the proposed algorithm, we compared the performance of the proposed algorithm and the 3D LiDAR-based SLAM (simultaneous localization and mapping) algorithm. As a result, it was confirmed that a precise 3D point cloud map can be generated with the low-cost sensor fusion system proposed in this paper.

• Journal of Cadastre & Land InformatiX
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• v.51 no.1
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• pp.111-124
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• 2021

Recently, Interest in the restoration and 3D reconstruction of cultural properties due to the fire of Notre Dame Cathedral on April 15, 2019 has been focused once again after the 2008 Sungnyemun fire incident in South Korea. In particular, research to restore and reconstruct the actual measurement of cultural properties using LiDAR(Light Detection and ranging) and conventional surveying, which were previously used, using various 3D reconstruction technologies, is being actively conducted. This study acquires data using unmanned aerial imagery of UAV(Unmanned Aerial Vehicle), which has recently established itself as a core technology in the era of the 4th industrial revolution, and the existing CRP(Closed Range Photogrammetry) and terrestrial LiDAR scanning for the Recumbent Buddha of Unju Temple. Then, the 3D reconstruction was performed with three fusion models based on SfM(Structure-from-Motion), and the reproducibility and accuracy of the models were compared and analyzed. In addition, using the best fusion model among the three models, the relationship with the Polar Star(Polaris) was confirmed based on the real world coordinates of the Recumbent Buddha, which contains the astronomical history of Buddhism in the early 11th century Goryeo Dynasty. Through this study, not only the simple external 3D reconstruction of cultural properties, but also the method of reconstructing the historical evidence according to the type and shape of the cultural properties was sought by confirming the historical evidence of the cultural properties in terms of spatial information.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.3
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• pp.11-19
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• 2010

In recent years, Korea has witnessed an increase to natural disasters such as landslides due to localized sudden and intensive rainfalls. Thus there have been researches on surface displacements to detect and monitor displacements in the areas prone to landslides by using high-precision and density numerical elevation data from LiDAR, which is an advanced 3D measuring equipment. However, the commercial software to process large-capacity LiDAR data, is expensive and difficult to be applied to specialized tasks such as analysis of landslide. In addition, there are no measures for many users to easily access diverse spatial information related to landslides and put it to intuitive uses. Thus this study developed an application program to analyze landslides by processing time series LiDAR data and intuitively serve many users with information about the topography and landslides of given areas. It analyzed the current state of landslides in the subject region through case study and proposed that 3D-based landslide and topography information can be served intuitively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.10
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• pp.1453-1461
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• 2022

The accuracy of peripheral object recognition algorithms using 3D data sensors such as LiDAR in autonomous vehicles has been increasing through many studies, but this requires high performance hardware and complex structures. This object recognition algorithm acts as a large load on the main processor of an autonomous vehicle that requires performing and managing many processors while driving. To reduce this load and simultaneously exploit the advantages of 3D sensor data, we propose 2D data-based recognition using the ROI generated by extracting physical properties from 3D sensor data. In the environment where the brightness value was reduced by 50% in the basic image, it showed 5.3% higher accuracy and 28.57% lower performance time than the existing 2D-based model. Instead of having a 2.46 percent lower accuracy than the 3D-based model in the base image, it has a 6.25 percent reduction in performance time.

• Korean Journal of Remote Sensing
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• v.39 no.5_2
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• pp.849-858
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• 2023

Investigating disaster sites such as earthquakes and landslides involves significant risks due to potential secondary disasters like facility collapse. In situations where direct access is challenging, there is a need to develop methods for safely acquiring high-precision 3D disaster information using light detection and ranging (LiDAR) equipped drone survey systems. In this study, the feasibility of using drone LiDAR in disaster scenarios was examined, focusing on the collapse accident at Jeongja Bridge in Bundang-gu, Seongnam City, in April 2023. High-density point clouds for the accident bridge were collected, and the bridge's 3D terrain information was reconstructed and compared to the measurement performance of 10 ground control points. The results showed horizontal and vertical root mean square error values of 0.032 m and 0.055 m, respectively. Additionally, when compared to a point cloud generated using ground LiDAR for the same target area, a vertical difference of approximately 0.08 m was observed, but overall shapes showed minimal discrepancies. Moreover, in terms of overall data acquisition and processing time, drone LiDAR was found to be more efficient than ground LiDAR. Therefore, the use of drone LiDAR in disaster sites with significant risks allows for safe and rapid onsite investigations.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.4
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• pp.3-9
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• 2007

Recently, the efforts of systematic understanding and utilization of geographic phenomenon for human life as a important factor among activity of mankind are increasing. It is necessary to express topography connected with space. Especially, the technology of geographic analysis using DEM can supply the information rapidly and accurately about elevation and terrain slope of the subject area under the necessity of high 3D quality geographic information. In this study, creating more precise DEM derived from LiDAR data, quantitative analysis on the subject area about elevation and terrain slope is done under comparison with Digital Topographic map Scale 1:1000. LiDAR data is more detailed than Digital Topographic map to express the elevation of the subject area ($39.89{\sim}77.48m$), and terrain slope by analysis using DEM derived from LiDAR data come out minutely about 90%. It can be concluded that the LiDAR data is very applicable and accurate for 3D topographic terrain slope analysis.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2015.11a
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• pp.221-223
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• 2015

해방70년을 맞이하는 차원에서 일제강점기 동안에 조선인 강재징용으로 구축된 진지갱도(신주백, 2003)에 대한 구조물의 분포와 활용에 대한 내역을 규명하고(황석규, 2006), 일제에 의하여 자행된 국토훼손의 실상 및 만행을 확인하여 분류하는데 있다. '한반도는 일제강점기 일본 제국의 군사요새였다'(이완희, 2014)고 제시하였듯이 조사탐사의 범위는 전국을 대상으로 하며, 진지갱도지역에 대한 3-D LiDAR 기법에 의한 도면작성으로 붕괴위험에 처한 진지동굴의 분포, 형상, 내용 등의 분석으로 문화재적 측면의 보전위한 기록물 구현방안에 있다.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.403-409
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• 2003

LiDAR(Light Detection and Ranging) is considered to be a very accurate and useful tool for detection and reconstruction of ground objects. LiDAR data has information about both intensity and x,y,z position of the ground objects. LiDAR data can be collected from both first and last-return, which are called multi-return, with up to 5 different returns simultaneously. In this paper, an approach to reconstruct buildings in urban area using LiDAR multi-return data is presented. The reconstructed buildings are combined with DEM(Digital Elevation Model) produced from DSM(Digital Surface Model) in given area to implement 3D modeling. As a result, it is shown that buildings in urban area can be reconstructed and classified by the integration of the multi-return and intensity data of LiDAR.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.383-388
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• 2004

The fusion of a different kind sensor is fusion of the obtained data by the respective independent technology. This is a important technology for the construction of 3D spatial information. particularly, information is variously realized by the fusion of LiDAR and mobile scanning system and digital map, fusion of LiDAR data and high resolution, LiDAR etc. This study is to generate union DEM and digital ortho image by the fusion of LiDAR data and high resolution image and monitor precisely topology, building, trees etc in urban areas using the union DEM and digital ortho image. using only the LiDAR data has some problems because it needs manual linearization and subjective reconstruction.