• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.6
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• pp.527-534
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• 2017

The purpose of this study is to develop unmanned equipment that can automatically move to the desired point and measure water quality at the correct depth. For this purpose, we constructed a water sampling lift and water sampling container, an unmanned vessel equipped with a VRS-GPS, an acoustic echo sounder, and a water quality sensor. Also, we developed an automatic navigation algorithm and program, an automatic water sampling program, and a water quality map generation program. As a result of the experiment in the detention pond, the unmanned vessel sailed along the planned route with an accuracy of about 93% within the error range of 3m. In addition, the water quality sensor installed in the lift was able to acquire the water quality of the target area in real time and transmit it to the server via wireless Internet, and it was possible to monitor the water quality of each site in real time. Through field experiments, the water sampling lift was able to control the desired length with an accuracy of about 94%. The stretch length accuracy experiment of the water sampling lift was impossible to measure directly in the water, so it was replaced land-based experiment. We also found some unstable problems due to the weight of the water sampling lift and the weight of the air compressor to operate the water container. Except these two problems, we accomplished purpose of this study. An automated water quality measurement method using an unmanned vessel can be used to measure the quality of water in a difficult to access area and to secure the safety of the worker.

• Geophysics and Geophysical Exploration
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• v.21 no.3
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• pp.150-161
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• 2018

Recently, unmanned aircraft EM (electromagnetic) survey based on ICT (Information and Communication Technology) has been widely utilized because of the efficiency in regional survey. We performed the theoretical study on the unmanned airship EM system developed by KIGAM (Korea Institute of Geoscience and Mineral resources) as part of the practical application of unmanned aircraft EM survey. Since this system has different configurations of transmitting and receiving loops compared to the conventional aircraft EM systems, a new technique is required for the appropriate interpretation of measured responses. Therefore, we proposed a method to calculate the EM field for the arbitrary shaped transmitter and verified its validity through the comparison with analytic solution for circular loop. In addition, to simulate the magnetic responses by three-dimensionally (3D) distributed anomalies, we have adapted our algorithm to 3D frequency-domain EM modeling algorithm based on the edge-FEM (finite element method). Though the analysis on magnetic field responses from a subsurface anomaly, it was found that the response decreases as the depth of the anomaly increases or the flight altitude increases. Also, it was confirmed that the response became smaller as the resistivity of the anomaly increases. However, a nonlinear trend of the out-of-phase component is shown depending on the depth of the anomaly and the used frequency, that makes it difficult to apply simple analysis based on the mapping of the magnitude of the responses and can cause the non-uniqueness problem in calculating the apparent resistivity. Thus, it is a prerequisite to analyze the appropriate frequency band and flight altitude considering the purpose of the survey and the site conditions when conducting a survey using the unmanned aircraft EM system.

• Journal of Space Technology and Applications
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• v.3 no.3
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• pp.213-228
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• 2023

Unmanned exploration rovers serve as tools for investigating mineral resources, mining, and carrying out various scientific on celestial bodies beyond Earth, acting on behalf of humans. Recently, not only the United States but also other countries such as Japan, India and China have been attempting to develop unmanned planetary exploration rovers for space development or have successfully operated them on other celestial bodies. This has accelerated the enthusiasm for space exploration and development. However, the development and operation of unmanned rovers for planetary exploration still entail significant costs and high risks, making it difficult for universities or companies to undertake such project independently without the guidance of financial backing from government entities. In this paper, we describe the recent development trends of micro-rovers, known as Cube Rovers, which inherit the concepts and definitions of traditional Cube Sat. We also introduce the potential and expectations of Cube Rovers through the necessity of their development and ongoing planetary exploration cases.

• Geophysics and Geophysical Exploration
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• v.25 no.1
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• pp.26-37
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• 2022

Recently, multiple methods using small aircraft for geophysical exploration have been suggested as a result of the development of information and communication technology. In this study, we introduce the hybrid unmanned aircraft electromagnetic system of the Korea Institute of Geosciences and Mineral resources, which is under development. Additionally, data processing and interpretation methods are suggested via the analysis of datasets obtained using the system under development to verify the system. Because the system uses a three-component receiver hanging from a drone, the effects of rotation on the obtained data are significant and were therefore corrected using a rotation matrix. During the survey, the heights of the source and the receiver and their offsets vary in real time and the measured data are contaminated with noise. The noise makes it difficult to interpret the data using the conventional method. Therefore, we developed a recurrent neural network (RNN) model to enable rapid predictions of the apparent resistivity using magnetic field data. Field data noise is included in the training datasets of the RNN model to improve its performance on noise-contaminated field data. Compared with the results of the electrical resistivity survey, the trained RNN model predicted similar apparent resistivities for the test field dataset.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.173-175
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• 2011

현대의 고도화된 산업현장에서 로봇의 사용은 보편화되고 있는 실정이다. 사람이 하기 어려운 작업을 대신함으로 인해 작업의 효율성과 생산의 극대화를 이루고 있다. 이런 가운데 로봇의 쓰임이 다양화되고 있는 추세에 있다. 그 중 한 분야로 무인 탐사 로봇을 만들어 보려 한다. 무인 탐사로봇의 주요기능으로는 악조건에서도 움직일 수 있는 이동체와 원거리에서도 사람이 실시간으로 볼 수 있는 영상전송기능 등을 필요로 한다. 이런 기능을 담당하는 부품들을 제어하기 위해 프로세서가 사용된다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.188-188
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• 2022

선박의 운용 효율을 높일 수 있는 방법인 무인 운용체계는 근래에 많은 관심을 받고 연구되어 왔다. 특히 무인수상선과 무인수중체의(USV-AUV)의 복합 운용 분야는 그 동안 어려움이 있었던 심해저 탐사 및 특수 임무 활용에 용이하여 많은 연구가 수행되고 있다. 본 연구에서는 쌍동선 형태인 무인수상선이 모선이 되고 무인수중체가 결합하여 충전하고 다시 진수하여 원거리 및 심해저 조건에서 무인수중체가 운용 가능하도록 하는 시스템의 일부인 USV-AUV의 docking을 위한 DP 시스템을 개발하고 선박해양플랜트연구소 해양공학수조에서 모형시험을 통해 이를 검증하였다. 또한, 실제 제작된 무인쌍동선과 추진 시스템을 활용하여 모형시험을 통해 검증한 DP 알고리즘을 적용하여 화성 제부도 앞바다에서 실선 DP 테스트를 수행하였다. 실 해역에서의 DP 시스템 테스트는 정확한 환경 조건의 계측 및 구현이 어려워 모형시험과 같은 정량적인 평가는 어렵지만, 정성적으로 DP 시스템이 작동하는 것을 확인할 수 있었다.

• Geophysics and Geophysical Exploration
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• v.8 no.1
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• pp.97-103
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• 2005

Recent development of marine magnetic gradient systems, using arrays of sensors, has made it possible to survey large contaminated areas very quickly. However, underwater Unexploded Ordnances (UXO) can be moved by water currents. Because of this mobility, the cleanup process in such situations becomes dynamic rather than static. This implies that detection should occur in near real-time for successful remediation. Therefore, there is a need for a fast interpretation method to rapidly detect signatures of underwater objects in marine magnetic data. In this paper, we present a fast method for location and characterization of underwater UXOs. The approach utilises gradient interpretation techniques (analytic signal and Euler methods) to locate the objects precisely. Then, using an iterative linear least-squares technique, we obtain the magnetization characteristics of the sources. The approach was applied to a theoretical marine magnetic anomaly, with random errors, over a known source. We demonstrate the practical utility of the method using marine magnetic gradient data from Japan.

• Geophysics and Geophysical Exploration
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• v.8 no.1
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• pp.104-111
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• 2005

Dmitri Donskoi, the Russian cruiser launched in 1883, is known to have sunk near Ulleung Island (East Sea, Korea) on May 29, 1905, while it was participating in the Russo-Japanese War. In order to find this ship, information about its possible location was obtained from Russian and Japanese maritime historical records. The supposed location of the ship was identified, and we conducted a five-year geophysical survey from 1999 to 2003. A reconnaissance three-dimensional topographic survey of the sea floor was carried out using multi-beam echo sounder, marine magnetometer, and side-scan sonar. An anomalous body identified through the initial reconnaissance survey was identified by a detailed survey using a remotely operated vehicle, deep-sea camera, and the mini-submarine Pathfinder. Interpretation of the acquired data showed that the ship is hanging on the side of a channel, at the bottom of the sea 400 m below sea level. The location is about 2 km from Port Jeodong, Uleung Island. We discovered 152 mm naval guns and other war materiel still attached to the hull of the ship. In addition, the remnants of the steering gear and other machinery that were burnt during the final action were found near the hull. Strong magnetic fields, resulting from the presence of volcanic rocks in the survey area, affected the resolution of the magnetic data gathered; as a result, we could not locate the ship reliably using the magnetic method. Severe sea floor topography in the gully around the hull gave rise to diffuse reflections in the side-scan sonar data, and this prevented us from identifying the anomalous body with the side-scan sonar technique. However, the sea-floor image obtained from the multi-bean echo sounder was very useful in verifying the location of the ship.

• Electronics and Telecommunications Trends
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• v.39 no.4
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• pp.10-20
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• 2024

Recent advancements in autonomous flight technologies for Unmanned Aerial Vehicles (UAVs) have greatly expanded their applicability for various tasks, including delivery, agriculture, and rescue. This article presents a comprehensive survey of path planning techniques in autonomous navigation and exploration that are tailored for UAVs. The robotics literature has studied path and motion planning, from basic obstacle avoidance to sophisticated algorithms capable of dynamic decision-making in challenging environments. In this article, we introduce popular path and motion planning approaches such as grid-based, sampling-based, and optimization-based planners. We further describe the contributions from the state-of-the-art in exploration planning for UAVs, which have been derived from these well-studied planners. Recent research, including the method we are developing, has improved performance in terms of efficiency and scalability for exploration tasks in challenging environments without human intervention. On the basis of these research and development trends, this article discusses future directions in UAV path planning technologies, illustrating the potential for UAVs to perform complex tasks with increased autonomy and efficiency.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.49.2-49.2
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• 2020

SDSS-III BOSS DR12 은하적색이동 탐사 자료 중 CMASS 표본을 사용하여 물질 분포에 대한 균일성 테스트를 수행하였다. 균일성의 비교 기준으로는 (i) 완전한 무작위 분포, (ii) Horizon Run 3 N-체 수치실험에서 얻은 헤일로 목록, 그리고 (iii) 물질 요동의 파워 스펙트럼과 로그정규분포를 가정해 얻은 모의 은하 목록을 사용하였다. 현재 관측된 영역에서 통계적으로 의미가 있는 가장 큰 규모인 300h-1Mpc까지 조사한 결과, 우리는 관측된 물질 분포가 무작위 분포와 비교하여 전혀 균일하지 않지만 우주론으로부터 구한 나머지 두 목록과는 부합함을 보였다. 우주의 균일 등방성을 제시하는 우주론 원리는 우주론의 이론적 전개에서 물질의 분포가 아닌 공간곡률에 적용된다. 지금 우주모형에서는 이 원리에서 벗어난 공간곡률의 정도가 충분히 작으므로 우주론 원리를 우주론에 적용하는 데 문제가 없다. 하지만 우리는 물질 분포가 균일 등방성에서 벗어난 정도가 상당함을 보였으며, 따라서 우주론 원리가 이론적 모형에 성공적으로 적용되지만 실제로 관측된 은하 분포에는 존재하지 않는다는 기존의 결론을 새로운 자료를 이용해 강화하였다.