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Analysis of Electromagnetic Waves Attenuation for Underwater Localization in Structured Environments
Daegil Park,Wan Kyun Chung,Jinhyun Kim 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.3
Range sensors based on electromagnetic (EM) waves attenuation along the target distance yield precise distance estimation with a high resolution, depending on the distance. However, their application in a structured underwater environment is difficult because the characteristics of EM waves attenuation in such environments are not considered. In this study, characteristics of EM waves propagation and signal interference effects due to structures are analyzed, and an EM waves distance-attenuation model for a structured underwater environment is proposed, along with sensor installation guidelines. The characteristics of EM waves propagation and the proposed sensor model are verified by several experiments, and the proposed sensor model yields greater accuracy positioning results compared to the previous model.
Development of Underwater Short-Range Sensor Using Electromagnetic Wave Attenuation
Daegil Park,Kyungmin Kwak,Wan Kyun Chung,Jinhyun Kim IEEE 2016 IEEE JOURNAL OF OCEANIC ENGINEERING - Vol.41 No.2
<P>In this paper, we discuss a novel underwater short-range sensor using electromagnetic (EM) wave attenuation. We use the revised Friis-Shelkunoff formula to calculate the EM wave attenuation underwater as a function of distance. This requires knowledge of the antenna gain underwater, which is very different from the gain in air, and also the attenuation constant which depends on the water conductivity. We calibrated the gain and attenuation in a ranging experiment and also in a 2-D localization experiment. Both methods agreed, confirming that in situ calibration of a 2-D localization experiment is feasible. The localization results show good accuracy, validating the sensor model and showing that multipath effects can be made negligible in such an experiment.</P>
박대길 ( Park Daegil ) 전북대학교 인문학연구소 2017 건지인문학 Vol.0 No.18
It is said that Jeon Bong-Jun(全琫準), Kim Gae-Nam(金開南), Son Hwa-Jung(孫華仲), Kim Deok-Myeong(金德明) and Choi Gyeong-Seon(崔景善) who were major figures of The Dong-hak Peasant`s revolution are `Five Leaders.` Four people, excluding Kim Gae-nam, were tried by the judical procedures, at least formally, left records of interrogation or judgment, and hanged in Seoul. They had the opportunity to proudly revealed the purpose and meaning of the revolution of Donghak Peasants which they took the lead. However, Kim Gae-nam did not even have the chance to express his will, as well as the judical procedures. Jeonragamsa(全羅監司) summarily executed Kim Gae-nam for the reason of `Escape and Rescue` and clearly wrote down the place of execution as “In the 20th of the 24 periods of the day, on the third of this month(December), gathered soldiers and people in Segyojang(西敎場), decapitate and expose his head, put it in a chest and sent it to Dosunmuyeong(都巡撫營) …” Thus, it shows the justification for Kim Gae-nam`s summary execution, the place and time of it, disposal of his body, and so on. However, contrary to `Escape and Rescue`, it is highly possible that the connection with DaewonGun(大院君) could be a decisive reason. Kim Gae-nam caused a second uprising to drive out the Japanese army and seize power. But there was communion with DaewonGun in his decision for uprising, which was an open secret at that time. Prejudication, that Kim Gae-nam who tried to reveal this publicly could cause another trouble if left untouched, made him be executed in haste. It was a very simple place to identify right away where Kim Gae-nam died for the country. Nevertheless, the background of the rise of Chorokbawwi(초록바위) view(theory) which has never been suggested any evidence was because of the name of the place that are not confirmed. In other words, this was a consequence of overlooking `Dongsoyimyeong(同所異名)`, which means the same place can be called differently such as Seokyojang(西敎場), Jangdae(將臺), under the Kongbukru(拱北 樓), and Supjeongi(숲정이). Therefore, the place of Kim Gae-nam`s death for the country is Supjeongi that is now called a representative Catholic Martyrs` Site, after Seokyojang was closed and neglected, as well as Seokyojang, Jangdae, under the Kongbukru in the record of 1894.
구조화된 공간에서의 수중 무선 센서 네트워크를 이용한 위치 추정 시스템
박대길(Daegil Park),곽경민(Kyungmin Kwak),정완균(Wan Kyun Chung),김진현(Jinhyun Kim) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.8
In this paper, an infrastructure-based localization method using underwater wireless sensor network (UWSN) is addressed. A localization using the UWSN is necessary to widen the usage of underwater applications, however it is very difficult to establish the UWSN due to the restrictions of water. In this paper, to extend the usage of UWSN at the infrastructure, we propose a sophisticated UWSN localization method using the Received Signal Strength Indicator (RSSI) of the electromagnetic waves. During the electromagnetic waves propagating in underwater, there arises a lot of attenuation according to the distance, while the attenuation shows uniformity according to the distance. Using this characteristics, the localization system in underwater infrastructure is proposed and the experimental results show the effectiveness.
박대길(Daegil Park),곽경민(Kyungmin Kwak),정재훈(Jaehoon Jung),김진현(Jinhyun Kim),정완균(Wan Kyun Chung) 한국해양공학회 2017 韓國海洋工學會誌 Vol.31 No.2
In this paper, we propose an underwater localization scheme through the fusion of an inertial navigation system (INS) and the received signal strength (RSS) of electromagnetic (EM) wave sensors to guarantee precise localization performance with high sampling rates. In this localization scheme, the INS predicts the pose of the unmanned underwater vehicle (UUV) by dead reckoning at every step, and the RF sensors corrects the UUV position functions using the Earth-fixed reference when the UUV is located in underwater wireless sensor networks (UWSN). The localization scheme and state modeling were conducted in the extended Kalman filter framework, and UUV localization experiments were conducted in a basin environment. The scheme achieved reliable localization accuracy during long-term navigation, demonstrating the feasibility of exploiting EM wave attenuation as Earth-fixed reference sensors.
Autonomous swimming technology for an AUV operating in the underwater jacket structure environment
이계홍,Daegil Park,Geonhui Ki 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.2
This paper presents the autonomous swimming technology developed for an Autonomous Underwater Vehicle (AUV) operating in the underwater jacket structure environment. To prevent the position divergence of the inertial navigation system constructed for the primary navigation solution for the vehicle, we've developed kinds of marker-recognition based underwater localization methods using both of optical and acoustic cameras. However, these two methods all require the artificial markers to be located near to the cameras mounted on the vehicle. Therefore, in the case of the vehicle far away from the structure where the markers are usually mounted on, we may need alternative position-aiding solution to guarantee the navigation accuracy. For this purpose, we develop a sonar image processing based underwater localization method using a Forward Looking Sonar (FLS) mounted in front of the vehicle. The primary purpose of this FLS is to detect the obstacles in front of the vehicle. According to the detected obstacle(s), we apply an Occupancy Grid Map (OGM) based path planning algorithm to derive an obstacle collision-free reference path. Experimental studies are carried out in the water tank and also in the Pohang Yeongilman port sea environment to demonstrate the effectiveness of the proposed autonomous swimming technology.
Kyungmin Kwak,Daegil Park,Wan Kyun Chung,Jinhyun Kim IEEE 2016 IEEE/ASME transactions on mechatronics Vol.21 No.3
<P>In this paper, an underwater 3-D spatial attenuation model of electromagnetic waves is proposed to establish a position recognition system in underwater 3-D space using distance estimation. The distance estimation is based on signal attenuation characteristics of electromagnetic waves radiated through several omnidirectional antennas. Positions in underwater environments have been predominantly estimated by an ultrasonic position recognition system using travel time and phase difference. However, such a system provides inaccurate estimation on account of the multipath effect in a structured environment or complex environment with many obstacles. A position estimation method that uses signal attenuation of electromagnetic waves has been proposed to overcome this limitation. That method can precisely estimate position on a structured 2-D plane. In this paper, an existing underwater position estimation system based on electromagnetic waves is expanded into 3-D space using the Friis formula and plane wave equation, thereby classifying attenuation characteristics of electromagnetic waves into the effects of medium, radiation, and antenna. These effects are summarized to deduce the signal attenuation characteristics of electromagnetic waves in 3-D space. In addition, the relative position (R, Theta, Phi) and attitude (phi, theta, psi) of transceiver antennas are used to define a coordinate system for 3-D estimation; moreover, an attenuation model is defined for individual factors in the coordinate system. A generalized attenuation model of an omnidirectional antenna in 3-D space is presented, and the validity of the proposed model is demonstrated through experiments. Based on the results, the proposed model demonstrates the potential application to an omnidirectional antenna and expansion into an attenuation model based on the 3-D position between random antennas.</P>