• Journal of Korean Philosophical Society
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• no.94
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• pp.53-87
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• 2011

Leibniz regards a corporeal substance, which is composed of monads, as 'one substance' and tries to prove that it has a true unity. This position seems to be contradictionary to his Monadology. Therefore, many scholars have ignored Leibniz's stand that corporeal substance is 'one substance', or consider this only as a stand from his theory of substance in his early works, which has been discarded afterwards. This Research will show that Leibniz adheres to this position throughout his lifetime; that although Leibniz uses the concepts such as substantial form and substantial bond to explain his stand, but the concept of substancial bond doesn't fit in with his philosophical system; that to explain the unity of the corporeal substance, the concept of substancial form and the theory of preestablished harmony are sufficient; and that nevertheless the stand that the corporeal substance is 'one substance' inconsistent with the position that the monad is 'one substance'; and that if Leibniz abandons that stand, the theory of the corporeal substance is a good foundation of his panorganism.

• Journal of Korean Society of Forest Science
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• v.112 no.3
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• pp.363-373
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• 2023

Forest biomass surveys are regularly conducted to assess and manage forests as carbon sinks. LiDAR (Light Detection and Ranging), a remote sensing technology, has attracted considerable attention, as it allows for objective acquisition of forest structure information with minimal labor. In this study, we propose a method for estimating overstory and understory biomass in forest stands using backpack laser scanning (BPLS) and unmanned aerial vehicle laser scanning (UAV-LS), and assessed its accuracy. For overstory biomass, we analyzed the accuracy of BPLS and UAV-LS in estimating diameter at breast height (DBH) and tree height. For understory biomass, we developed a multiple regression model for estimating understory biomass using the best combination of vertical structure metrics extracted from the BPLS data. The results indicated that BPLS provided accurate estimations of DBH (R² =0.92), but underestimated tree height (R² =0.63, bias=-5.56 m), whereas UAV-LS showed strong performance in estimating tree height (R² =0.91). For understory biomass, metrics representing the mean height of the points and the point density of the fourth layer were selected to develop the model. The cross-validation result of the understory biomass estimation model showed a coefficient of determination of 0.68. The study findings suggest that the proposed overstory and understory biomass survey methods using BPLS and UAV-LS can effectively replace traditional biomass survey methods.

• Proceedings of the Korean Institute of Landscape Architecture Conference
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• 2022.10a
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• pp.118-119
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• 2022

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.768-773
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• 2020

In large-scale land development for the rational use and management of national land resources, the use of geospatial information is essential for the efficient management of projects. Recently, drone LiDAR (Light Detection And Ranging) has attracted attention as an effective geospatial information construction technique for large-scale development areas, such as housing site construction and open-pit mines. Drone LiDAR can be classified into a method using SLAM (Simultaneous Localization And Mapping) technology and a GNSS (Global Navigation Satellite System)/IMU (Inertial Measurement Unit) method. On the other hand, there is a lack of analytical research on the application of drone LiDAR or the characteristics of each method. Therefore, in this study, data acquisition, processing, and analysis using SLAM and GNSS/IMU type drone LiDAR were performed, and the characteristics and utilization of each were evaluated. As a result, the height direction accuracy of drone LiDAR was -0.052~0.044m, which satisfies the allowable accuracy of geospatial information for mapping. In addition, the characteristics of each method were presented through a comparison of data acquisition and processing. Geospatial information constructed through drone LiDAR can be used in several ways, such as measuring the distance, area, and inclination. Based on such information, it is possible to evaluate the safety of large-scale development areas, and this method is expected to be utilized in the future.

• Journal of the Korea Computer Graphics Society
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• v.27 no.5
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• pp.63-71
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• 2021

Among drone autonomous flight technologies, obstacle avoidance is a very important technology that can prevent damage to drones or surrounding environments and prevent danger. Although the LiDAR sensor-based obstacle avoidance method shows relatively high accuracy and is widely used in recent studies, it has disadvantages of high unit price and limited processing capacity for visual information. Therefore, this paper proposes an obstacle avoidance algorithm for drones using camera-based PPO(Proximal Policy Optimization) reinforcement learning, which is relatively inexpensive and highly scalable using visual information. Drone, obstacles, target points, etc. are randomly located in a learning environment in the three-dimensional space, stereo images are obtained using a Unity camera, and then YOLov4Tiny object detection is performed. Next, the distance between the drone and the detected object is measured through triangulation of the stereo camera. Based on this distance, the presence or absence of obstacles is determined. Penalties are set if they are obstacles and rewards are given if they are target points. The experimennt of this method shows that a camera-based obstacle avoidance algorithm can be a sufficiently similar level of accuracy and average target point arrival time compared to a LiDAR-based obstacle avoidance algorithm, so it is highly likely to be used.

• Journal of Korea Water Resources Association
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• v.55 no.2
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• pp.135-145
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• 2022

This study aims to verify the Drone utilization and the accuracy of the global navigation satellite system (GNSS), Drone RGB (Photogrammetry) (D-RGB), and Drone LiDAR (D-LiDAR) surveying performance in the downstream reaches of the local stream. The results of the measurement of Ground Control Point (GCP) and Check Point (CP) coordinates confirmed the excellence. This study was carried out by comparing GNSS, D-RGB, and D-LiDAR with the values which the hydraulic characteristics calculated using HEC-RAS model. The accuracy of three survey methods was compared in the area of the study which is the ownership station, to 6 GCP and 3 CP were installed. The comparison results showed that the D-LiDAR survey was excellent. The 100-year frequency design flood discharge was applied in the channel sections of the small stream. As a result of D-RGB surveying 2.30 m and D-LiDAR 1.80 m in the average bed elevation, and D-RGB surveying 4.73 m and D-LiDAR 4.25 m in the average flood condition. It is recommended that the performance of D-LiDAR surveying is efficient method and useful as the surveying technique of the geospatial information using the drone equipment in stream channel.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.697-702
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• 2023

Recently, with the introduction of drones, a core technology of the 4th industrial revolution, various convergence education using drones is being conducted in school education sites. In particular, drone theory and practice education is being conducted in connection with free semester classes and career exploration. The drone convergence education program has higher learner satisfaction than simple demonstration and practice education, and the learning effect is high due to direct practical experience. However, since practical education is being conducted for a large number of learners, it is impossible to restrict and control the flight of a large number of drones in a limited place. In this paper, we propose a monitoring system that allows the instructor to monitor multiple drones in real time and learners to recognize collisions between drones in advance when multiple drones are operated, focusing on education operated in schools. The communication module used in the experiment was equipped with GPS in Murata LoRa, and the server and client were configured to enable monitoring based on the location data received in real time. The performance of the proposed system was evaluated in an open space, and it was confirmed that the communication signal was good up to a distance of about 120m. In other words, it was confirmed that 25 educational drones can be controlled within a range of 240m and the instructor can monitor them.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.579-586
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• 2019

The purpose of this study is to determine the rapid saving of life through the drones when natural disasters such as earthquake and fire occur. Drones are equipped with riders, temperature, hazardous gas sensors and wireless cameras are registered with the application server for monitoring the disaster site and real-time monitoring functions are performed to identify the situation on site before rescuing personnel are active. When monitoring finds a person to save, the application server provides real-time image information for effective life-saving.

• Proceedings of the Korean Society of Crop Science Conference
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• 2020.11a
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• pp.75-75
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• 2020

• Cartoon and Animation Studies
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• s.48
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• pp.199-215
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• 2017

Recently, a drone is used for the general purpose application although the drone was builtfor the military purpose. A drone is actively used for the creation of contents, and an image acquisition. In this paper, we develop a 3D library module platform using 3D mesh model data, which is generated by a drone image and its point cloud. First, a lot of 2D image data are taken by a drone, and a point cloud data is generated from 2D drone images. A 3D mesh data is acquired from point cloud data. Then, we develop a service library platform using a transformed 3D data for multi-purpose uses. Our platform with 3D data can minimize the cost and time of contents creation for special effects during the production of a movie, drama, or documentary. Our platform can contribute the creation of experts for the digital contents production in the field of a realistic media, a special image, and exhibitions.