• KIISE Transactions on Computing Practices
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• v.23 no.10
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• pp.588-593
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• 2017

In this paper, we propose a LiDAR driver that virtualizes multiple inexpensive LiDARs (Light Detection and Ranging) with a smaller number of scan channels on an autonomous vehicle to replace a single expensive LiDAR with a larger number of scan channels. As a result, existing SLAM (Simultaneous Localization And Mapping) algorithms can be used with no modifications developed assuming a single LiDAR. In the paper, the proposed driver was implemented on the Robot Operating System and was evaluated with an existing SLAM algorithm. The results show that the proposed driver, combined with a filter to control the density of points in a 3D map, is compatible with the existing algorithm.

• Journal of Digital Contents Society
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• v.18 no.5
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• pp.989-994
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• 2017

In this paper, we propose a pothole detection system using 2D LiDAR and a pothole detection algorithm. Conventional pothole detection methods can be divided into vibration-based method, 3D reconstruction method, and vision-based method. Proposed pothole detection system uses two inexpensive 2D LiDARs and improves pothole detection performance. Pothole detection algorithm is divided into preprocessing for noise reduction, clustering and line extraction for visualization, and gradient function for pothole decision. By using gradient of distance data function, we check the existence of a pothole and measure the depth and width of the pothole. The pothole detection system is developed using two LiDARs, and the 3D pothole detection performance is shown by detecting a pothole with moving LiDAR system.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.3
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• pp.387-396
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• 2023

The representative equipments currently used for weather observations are meteorological masters and wind lidars. According to international regulations, meteorological masters can be used for standalone measurements, but in case of wind lidars, it is mandatory to install a meteorological master that matches the height of the bottom of the wind turbine blade or a 40m meteorological masters and correct the measurement data. Turbulence flow occurs frequently at altitudes below 100m due to its nature, and wind lidars are more susceptible to the effects of turbulence than meteorological masters. However, while the turbulence intensity for meteorological masters is specified by international regulations, there is no separated specification for wind lidars. This study collected data measured under the same conditions using both meteorological masters and wind LiDARs, analyzed the uncertainties and turbulence intensity ratio. The analysis of the data showed that there were partial sections where the proportion of turbulent flow intensity exceeded 3%. Therefore, it is suggested to include a specification for the turbulence intensity error rate for wind LiDARs in the international regulations.

• Korean Journal of Remote Sensing
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• v.24 no.4
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• pp.333-340
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• 2008

For the indoor spatial modeling by terrestrial LiDAR and the analyzing its positional accuracy result, two terrestrial LiDARs which have different specification each other were used at test site. This paper shows disparity of accuracy between (1) the structural coordinate transformation by point cloud unit using control points and (2) the relative registration among all point cloud units then structural coordinate transformation in bulk, under condition of limited number of control points. As results, the latter had smaller size and distribution of errors than the former although different specifications and acquistion methods are used.

• Journal of Environmental Science International
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• v.31 no.6
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• pp.479-490
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• 2022

This study was to evaluate the utilization of terrestrial light detection and ranging for forest inventory in coniferous forests. Heights and diameter of the stand trees were measured manually using the traditional measurement method and the method using terrestrial LiDAR. The results of two methods were compared and analyzed to evaluate accuracy and feasibility. The terrestrial LiDAR used fixed and handy types to compare the accuracy between different operational methods. Comparative analyses used a paired t-test and Bland-Altman plot analysis. In the case of tree heights, the average of difference between the traditional method and terrestrial LiDAR for each plot was 0.81 m, -0.07 m, and 0.13 m for fixed type; 2.88 m, 1.19 m, and 0.93 m for the handy type. In the case of tree diameter at breast height, the average value of the difference between traditional methods and terrestrial LiDAR for each plot was 0.13 cm, -0.66 cm, and -0.03 cm for fixed type; 2.36 cm, 2.13 cm, and 1.92 cm for the handy type. The values from the method using the fixed type was highly consistent with that using the traditional measurement methods; the average difference was closer to zero. The crown density influences the precision of the height measurement using terrestrial LiDAR in coniferous forests. Therefore, future studies should focus on verifying the accuracy of terrestrial LiDAR in forests and on expanding the utilization of terrestrial LiDARs according to their operational methods.

• New & Renewable Energy
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• v.16 no.3
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• pp.35-41
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• 2020

In this study, a floating LiDAR system (FLS) is investigated through a field test involving two steps. First, correlations among wind speeds, measured using the met mast and two LiDARs, are computed to analyze the acceptance criteria of LiDAR for measuring wind speed. The results of the analysis show that the slopes of single variant regression between mean wind speeds are below 1.03 and the coefficient of determination is above 0.97. Next, correlations among wind speeds measured using the FLS and a fixed LiDAR are determined through a field test carried out in Doomi-doo, Tong-young, Gyeongsangnam-do. The FLS is installed 300 m away from the fixed LiDAR on the ground. The results show that the slope of single variant regression is approximately 1.0275 and the coefficient of determination is above 0.971. According to the IEA/wind 18 recommendation, it is found that the developed FLS measures valid wind speeds to assess wind resources for the development of offshore wind farms.

• Wind and Structures
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• v.24 no.6
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• pp.613-635
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• 2017

Strong downslope windstorms often occur in the Liguria Region. This part of North-Western Italy is characterised by an almost continuous mountain range along its West-East axis consisting of Maritime Alps and Apennines, which separate the Padan Plain to the North from the Mediterranean Sea to the South. Along this mountain range many valleys occur, frequently perpendicular to the mountain range axis, where strong gap flows sometimes develop from the top of the mountains ridge to the sea. In the framework of the European projects "Wind and Ports" and "Wind, Ports, and Sea", an anemometric monitoring network made up of 15 (ultra)sonic anemometric stations and 2 LiDARs has been realised in the three main commercial ports of Liguria. Thanks to this network two investigations are herein carried out. First, the wind climatology and the main statistical parameters of one Liguria valley have been studied through the analysis of the measurements taken along a period of 4 years by the anemometer placed at its southern exit. Then, the main characteristics of two strong gap flows that occurred in two distinct valley of Liguria are examined. Both these studies focus, on the one hand, on the climatological and meteorological characterisation of the downslope wind events and, on the other hand, on their most relevant quantities that can affect wind engineering problems.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.4
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• pp.194-210
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• 2023

LiDAR plays a key role in autonomous vehicles, where it is used to detect the environment in place of the driver's eyes, and its role is expanding. In recent years, there has been a growing need to test the performance of LiDARs installed in autonomous vehicles. Many LiDAR performance tests have been conducted in simulated and indoor(lab) environments, but the number of tests in outdoor(field) and real-world road environments has been minimal. In this study, we compared LiDAR performance under the same conditions lab and field to determine the relationship between lab and field tests and to establish the characteristics and roles of each test environment. The experimental results showed that LiDAR detection performance varies depending on the lighting environment (direct sunlight, led) and the detected object. In particular, the effect of decreasing intensity due to increasing distance and rainfall is greater outdoors, suggesting that both lab and field experiments are necessary when testing LiDAR detection performance on objects. The results of this study are expected to be useful for organizations conducting research on the use of LiDAR sensors and facilities for LiDAR sensors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.312-320
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• 2020

3D scanning began in the field of manufacturing. In the construction field, a BIM (Building Information Modeling)-based 3D modeling environment was developed and used for the overall construction, such as factory prefabrication, structure construction inspection, plant facility, bridge, tunnel structure inspection using 3D scanning technology. LiDARs have higher accuracy and density than mobile scanners but require longer registration times and data processing. On the other hand, in interior building space management, relatively high accuracy is not needed, and the user can conveniently move with a mobile scan system. This study derives considerations for the development of Simultaneous Localization and Mapping (SLAM)-based Scan Backpack systems that move freely and support real-time point cloud registration. This paper proposes the mobile scan system, framework, and component structure to derive the considerations and improve scan productivity. Prototype development was carried out in two stages, SLAM and ScanBackpack, to derive the considerations and analyze the results.

• Journal of Auto-vehicle Safety Association
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• v.9 no.2
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• pp.6-12
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• 2017

An autonomous driving system based on a precise digital map is developed. The system is implemented to the Hyundai's Tucsan fuel cell car, which has a camera, smart cruise control (SCC) and Blind spot detection (BSD) radars, 4-Layer LiDARs, and a standard GPS module. The precise digital map has various information such as lanes, speed bumps, crosswalks and land marks, etc. They can be distinguished as lane-level. The system fuses sensed data around the vehicle for localization and estimates the vehicle's location in the precise map. Objects around the vehicle are detected by the sensor fusion system. Collision threat assessment is performed by detecting dangerous vehicles on the precise map. When an obstacle is on the driving path, the system estimates time to collision and slow down the speed. The vehicle has driven autonomously in the Hyundai-Kia Namyang Research Center.