초빙논문 : 지뢰탐지를 위한 GPR 시스템의 개발

( Motoyuki Sato ),( Jun Fujiwara ),( Feng Xuan ),( Zheng Shu Zhou ),( Takao Kobayashi ) 한국지구물리탐사학회 2005 지구물리와 물리탐사 Vol.8 No.4

Borehole radar for environment study

Motoyuki Sato 한국암반공학회 2003 한국암반공학회 학술대회 및 세미나 자료집 Vol.- No.-

GPR Development for Landmine Detection

Sato, Motoyuki,Fujiwara, Jun,Feng, Xuan,Zhou, Zheng-Shu,Kobayashi, Takao Korean Society of Earth and Exploration Geophysici 2005 지구물리와 물리탐사 Vol.8 No.4

Under the research project supported by Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), we have conducted the development of GPR systems for landmine detection. Until 2005, we have finished development of two prototype GPR systems, namely ALIS (Advanced Landmine Imaging System) and SAR-GPR (Synthetic Aperture Radar-Ground Penetrating Radar). ALIS is a novel landmine detection sensor system combined with a metal detector and GPR. This is a hand-held equipment, which has a sensor position tracking system, and can visualize the sensor output in real time. In order to achieve the sensor tracking system, ALIS needs only one CCD camera attached on the sensor handle. The CCD image is superimposed with the GPR and metal detector signal, and the detection and identification of buried targets is quite easy and reliable. Field evaluation test of ALIS was conducted in December 2004 in Afghanistan, and we demonstrated that it can detect buried antipersonnel landmines, and can also discriminate metal fragments from landmines. SAR-GPR (Synthetic Aperture Radar-Ground Penetrating Radar) is a machine mounted sensor system composed of B GPR and a metal detector. The GPR employs an array antenna for advanced signal processing for better subsurface imaging. SAR-GPR combined with synthetic aperture radar algorithm, can suppress clutter and can image buried objects in strongly inhomogeneous material. SAR-GPR is a stepped frequency radar system, whose RF component is a newly developed compact vector network analyzers. The size of the system is 30cm x 30cm x 30 cm, composed from six Vivaldi antennas and three vector network analyzers. The weight of the system is 17 kg, and it can be mounted on a robotic arm on a small unmanned vehicle. The field test of this system was carried out in March 2005 in Japan.

ALIS : GPR System for Humanitarian Demining and Its Deployment in Cambodia

Motoyuki Sato,Yuya Yokota,Kazunori Takahashi 한국전자파학회JEES 2012 Journal of Electromagnetic Engineering and Science Vol.12 No.1

Humanitarian demining is very important issue not only in mine affected courtiers but also for the courtiers which are technically, politically and financially supporting the mine affected courtiers. In order to achieve higher efficiency of the mine clearance operation, new technologies can significantly contribute to the societies. Since 2002, Tohoku University, Japan has developed a sensor system “ALIS” for humanitarian demining. ALIS is a hand-held dual sensor, which combines an electromagnetic induction sensor (EMI) and a Ground Penetrating Radar (GPR). ALIS has a real-time sensor tracking system based on a CCD camera and which enables the image reconstruction. We have tested ALIS in Cambodia and found that it can eliminate more than 70 % metal fragments. Since 2009, 2 sets of ALIS have detected more than 80 anti-personnel mines, and cleared more than 137,000 ㎡ in Cambodia.

지뢰탐지를 위한 GPR 시스템의 개발

Motoyuki Sato,Jun Fujiwara,Xuan Feng,Zheng-Shu Zhou,Takao Kobayashi 한국지구물리탐사학회 2005 지구물리와 물리탐사 Vol.8 No.4

일본 문부과학성의 연구 지원하에 지뢰 탐지를 위한 GPR 시스템 개발에 관한 연구를 수행하였다. 2005 년도 까지 두 종류의 새로운 지뢰탐지 GPR 시스템 원형의 개발을 완성하였으며 이를 ALIS (Advanced Landmine Imaging System)와 SAR-GPR (Synthetic Aperture Radar – Ground Penetrating Radar)이라고 명명하였다. ALIS는 금속탐지기와 GPR을 결합한 새로운 형태의 휴대용 지뢰탐지 시스템이다. 센서의 위치를 실시간으로 추적하는 시스템을 장착하여 센서 에 감지된 신호를 실시간으로 영상화할 수 있도록 하였으며, 센서 위치의 추적은 센서의 손잡이에 장착한 CCD 카메라 만을 이용하여 가능하도록 고안하였다. 그리고 GPR과 금속탐지기 신호를 CCD 카메라에 포착된 영상에 중첩하여 동시 에 영상화하도록 설계하였기 때문에 매설된 탐지 목적물을 용이하게 그리고 신뢰할 만한 수준으로 탐지하고 구별할 수 있다. 2004 년 12월에 아프가니스탄에서 ALIS의 현장 검증 실험을 수행하였으며, 이를 통해 이 연구에서 개발한 시스템 을 이용하여 매설된 대인지뢰를 탐지할 수 있을 뿐만 아니라 대인지뢰와 금속 파편의 구분 또한 가능함을 보였다. SARGPR은 이동 로보트에 장착한 지뢰탐지 시스템으로 GPR과 금속탐지기 센서로 구성된다. 다수의 송, 수신 안테나로 구성 된 안테나 배열을 채택하여 개선된 신호처리 기법의 적용을 가능하며, 이를 통해 좀 더 나은 지하 영상의 획득이 가능하 다. SAR-GPR에 합성개구 레이다 알고리듬을 채용함으로써 원하지 않는 클러터(clutter) 신호를 억제하고 불균질도가 높 은 매질 내부에 매설된 목적물을 영상화할 수 있다. SAR-GPR은 새로이 개발한 휴대용 벡터 네트워크 분석기를 이용한 스텝 주파수 레이다 시스템(stepped frequency radar system)으로 6 개의 Vivaldi 안테나와 3 개의 벡터 네트워크 분석기 로 구성된다. SAR-GPR의 크기는 30 cm × 30 cm × 30 cm, 중량은 17 kg 정도이며 소형 무인 차량의 로보트 팔에 장 착된다. 이 시스템의 현장 적용 실험은 2005 년 3 월 일본에서 성공적으로 실시된 바 있다.

Driving Simulator Study for Driver Behavior Assessment while Driving on Downgrades with Different Gradients

Toshihisa Sato,Motoyuki Akamatsu,Nobuhiro Imacho,Takashi Sato,Yuji Munehiro,Yoshiyuki Yoneyama,Yoshiyuki Tashiro 한국자동차공학회 2008 한국자동차공학회 Symposium Vol.2008 No.9

This paper describes an investigation of driver’s behavior assessment while driving on downgrades with different gradients and effect of road safety countermeasures using a coloured pavement or a light-emitting delineator. The driving simulator used in the experiments consists of 300-degree fields of view screen, a hexapod motion platform, a sound system with spatial placed eight speakers, and so on. The target was two kinds of downgrades after curved and more gradual downgrade section: one is the existent downgrade with 8% gradient and with one traffic lane in each direction, and another has 7% gradient with two lanes that will be constructed for improvement of the existing downgrade. The existent downgrade has a temporary road structure and we investigated the effective countermeasures of the coloured pavement or a light-emitting delineator to reduce driving speed on the temporary downgrade. The simulator precisely represented these road structures using CAD data of the real and planned roads. Two downgrade sections were connected each other in one experimental route in order to compare the driving between on different downgrades and the driving with and without the countermeasures. The results of participated 31 drivers suggest that there are almost no differences in road safety between the existent and improved downgrades in terms of objective and subjective assessments. The evaluation results of the effect of the countermeasures imply the necessity of the interface design that affords drivers easy recognition of onset location of the steep downgrade.

Comparison of Car Following Behavior between UK and Japan

Toshihisa Sato,Motoyuki Akamatsu,Pengjun Zheng,Mike McDonald 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

This paper describes a comparison study of driver’s car following behavior between Southampton (UK) and Tsukuba (Japan). AIST and TRG have developed instrumented vehicles, and filed experiments for behavioral datacollection were conducted in each country. The research focused on the static (distribution of inter-vehicle distances and desired headway distance) and the dynamic aspects (acceleration rate according to relative speeds and distancedivergence) of the car following behavior. The dynamic aspect was evaluated using fuzzy logic car following model developed at TRG. The results suggest that Southampton drivers tend to take shorter distance headway and acceleratemore strongly when the velocity of the leading vehicle is faster. The distance headway of Tsukuba drivers was found tobe longer and the deceleration was stronger while approaching a leading vehicle. The implications and future directionof car-following behavior comparison study are discussed.

A new approach to enhancement of ground penetrating radar target signals by pulse compression

Gaballah, Mahmoud,Sato, Motoyuki Korean Society of Earth and Exploration Geophysici 2009 지구물리와 물리탐사 Vol.12 No.1

Ground penetrating radar (GPR) is an effective tool for detecting shallow subsurface targets. In many GPR applications, these targets are veiled by the strong waves reflected from the ground surface, so that we need to apply a signal processing technique to separate the target signal from such strong signals. A pulse-compression technique is used in this research to compress the signal width so that it can be separated out from the strong contaminated clutter signals. This work introduces a filter algorithm to carry out pulse compression for GPR data, using a Wiener filtering technique. The filter is applied to synthetic and field GPR data acquired over a buried pipe. The discrimination method uses both the reflected signal from the target and the strong ground surface reflection as a reference signal for pulse compression. For a pulse-compression filter, reference signal selection is an important issue, because as the signal width is compressed the noise level will blow up, especially if the signal-to-noise ratio of the reference signal is low. Analysis of the results obtained from simulated and field GPR data indicates a significant improvement in the GPR image, good discrimination between the target reflection and the ground surface reflection, and better performance with reliable separation between them. However, at the same time the noise level slightly increases in field data, due to the wide bandwidth of the reference signal, which includes the higher-frequency components of noise. Using the ground-surface reflection as a reference signal we found that the pulse width could be compressed and the subsurface target reflection could be enhanced.

Evaluation of Van Khan Tooril's castle, an archaeological site in Mongolia, by Ground Penetrating Radar

Khuut, Tseedulam,Sato, Motoyuki Korean Society of Earth and Exploration Geophysici 2009 지구물리와 물리탐사 Vol.12 No.1

We report an implementation of the Ground Penetrating Radar (GPR) survey at a site that corresponds to a ruined castle. The objective of the survey was to characterise buried archaeological structures such as walls and tiles in Van Khan Tooril's Ruin, Mongolia, by 2D and 3D GPR techniques. GPR datasets were acquired in an area 10mby 9 m, with 10 cm line spacing. Two datasets were collected, using GPR with 500MHz and 800MHz frequency antennas. In this paper, we report the use of instantaneous parameters to detect archaeological targets such as tile, brick, and masonry by polarimetric GPR. Radar polarimetry is an advanced technology for extraction of target scattering characteristics. It gives us much more information about the size, shape, orientation, and surface condition of radar targets. We focused our interpretation on the strongest reflections. The image is enhanced by the use of instantaneous parameters. Judging by the shape and the width of the reflections, it is clear that moderate to high intensity response in instantaneous amplitude corresponds to brick and tiles. The instantaneous phase map gave information about the location of the targets, which appeared as discontinuities in the signal. In order to increase our ability to interpret these archaeological targets, we compared the GPR datasets acquired in two orthogonal survey directions. A good correlation is observed for the alignments of reflections when we compare the two datasets. However, more reflections appear in the north-south survey direction than in the west-east direction. This is due to the electric field orientation, which is in the horizontal plane for north-south survey directions and the horizontally polarised component of the backscattered high energy is recorded.

GPR을 이용한 몽고 유적지 반 칸 투리일의 성 (Van Khan Tooril`s castle)의 평가

( Tseedulam Khuut ),사등원지 ( Motoyuki Sato ) 한국지구물리탐사학회 2009 지구물리와 물리탐사 Vol.12 No.1