• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.6
• /
• pp.546-554
• /
• 2015

Ultra-wideband(UWB) radar is widely used in many penetration radar applications, such as ground-penetrating radar and foliage-penetrating radar, because it has many advantages in detecting concealed objects. One type of UWB radar system is random noise radar, which many be robust to jamming environment. However conventional random noise radar requires high-speed analog-to-digital convertor(ADC) for matched filtering. In this thesis, a pseudo-random noise radar system that maintains anti-jamming characteristics but does not require high-speed ADC is researched. and The UWB system is implemented in a low frequency system, and its performance has been demonstrated by experiment, which proves the concept of the proposed pseudo-random noise radar system.

• Tunnel and Underground Space
• /
• v.7 no.4
• /
• pp.274-283
• /
• 1997

It is necessary to estimate the soundness of tunnel using non-destructive tests(NDT) for effective repairs and maintenances. But, the state of tunnel lining could not be investigated using previous non-destructive techniques, due to the various types of support and accessibility only from one side in tunnel lining. Recently, the various non-destructive techniques such as ground penetrating radar(GPR) have been researched and developed for inspection of tunnel lining. In this study, the usefulness and applicability of GPR test in tunnel lining inspection has been investigated through model tests and tunnel site application. This paper described the tunnel lining inspection for lining thickness, cavity and support using GPR test. From the results of tests, we have concluded that GPR test are very useful and effective techniques to look into the interior of lining and measure the lining thickness.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.346-353
• /
• 2005

Track substructure(ballast, subgrade) should have sufficient strength and adequate stiffness to fully support track superstructure(rail, fastener, sleeper). Vertical support stiffness of track comes from the sufficient thickness, adequate strength and stiffness of material of substructure layers. Since the vertical support stiffness of track substructure is closely related with the track geometry, the evaluation of the stiffness is very important to understand the track states. This paper introduces the system, which are composed of Ground Penetrating Radar(GPR), Portable Ballast Sampler(PBS), and Light Falling Weight Deflectometer(LFWD), to evaluate substructure condition and summarizes the field test results performed with the reliable system.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.4 no.4
• /
• pp.101-107
• /
• 2000

In this study, the Ground Penetrating Radar(GPR) was tested to evaluate the condition of concrete decks. Test results obtained by CPR were compared with values measured from drilled cores and damage mapping by the visual survey. It is shown that GPR can provide highly accurate measurements of layer properties of concrete decks and can map areas of deterioration in bridge decks by dielectric constants. The deck condition can be grouped into categories of "good" or "distressed". The ground penetrating radar data shows promise for producing rapid and accurate condition assessment for bridge decks. And these data can be used to evaluate highway bridge condition and make cost-effective bridge deck rehabilitation by accurately estimating the quantity of deteriorated concrete.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.10b
• /
• pp.761-766
• /
• 1998

GPR(Ground Penetrating Radar) designed with a digital-based signal processing technology utilizes to identify very easily the location, the thickness and the level of either an underground embedment or an underground structure. Prior to use of this GPR equipment on pavement of about 15cm thick, the equipment should foremost be calibrated on a known sample under known condition. The purpose of this study is to verify the applicability of the GPR equipment to a model pavement of about 15cm thick. As part of this effort, the general approach of this study is to verify the applicability of the GPR equipment by various thickness levels and its error ranges thru a statistical analysis.

• Journal of the Korean Geophysical Society
• /
• v.6 no.4
• /
• pp.269-276
• /
• 2003

Sub-bottom profile were conducted in Chungju Regulation Lake by use of ground penetrating radar(GPR). The survey area covers approximately 1,000,000 $m^2$ and total survey line length is about 5km and more. GPR surveys with GPS system were made across and transverse direction of the lake. From the survey results of GPR, it could be possible to distinguish the gravel and/or sand dominant bed from silt and/or clay material dominant bed.

• 한국지구물리탐사학회:학술대회논문집
• /
• 1999.08a
• /
• pp.65-91
• /
• 1999

More than 6 years passed until GPR was introduced to our country. GPR method is now widely used in construction site because of its various applicability, convenient handling and low cost. We discussed the characteristics and limits of GPR method with various case study.

• Proceedings of the KIEE Conference
• /
• 2005.07c
• /
• pp.2342-2344
• /
• 2005

초광대역 임펄스를 이용한 비파괴 지중 매설물 탐지용 지반 탐사 레이더(Ground penetrating image radar: GPR)를 개발하였다. 최대 탐사 깊이를 고려하여, 900 picosecond(ps) 상승 시간을 갖는 초광대역 임펄스를 설계하였고, 임펄스 발생기의 주파수 특성을 고려하여, 소형 평판형 다이폴 안테나가 설계되었다. 또한, 지중으로부터 반사되는 신호를 수신하기 위해서 고속의 A/D를 사용하였다. 측정은 송수신 안테나의 간격을 고정한 Bistatic 방식을 사용하였으며, 지중 매설물의 영상처리 판별을 위해 마이그레이션(migration) 기법을 사용하였다. 개발된 시스템은 금속 물체와 비금속 물체가 매설된 실증 시험장에서 시험되었고, 평면 해상도 및 깊이에 대한 해상도가 우수함을 보였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.4
• /
• pp.565-574
• /
• 2000

A new ground penetrating radar imaging method for the estimation of buried artificial structures location and their approximate shapes in dispersive lossy ground is investigated. Fundamental idea is based on estimating delayed time and amplitude retrieval coefficients from scattered signals by buried scatterers. Using absolute value integration of each scanning site not only improve the accuracy of measured scattered signal, but also offers convenient ways to extract the image of buried structures. Multi-term Debye model was employed to describe a dispersive and lossy ground medium. We used the finite difference time domain method to discretize the wave equation in continuous form into the machine suitable form. This imaging method uses a new wave path tracing technique in time domain, which is helpful to identify the exact position of buried structures against the ground surface fluctuations.

• Journal of Cadastre & Land InformatiX
• /
• v.45 no.2
• /
• pp.131-147
• /
• 2015

In modern society, as to the underground urban infrastructure facilities(communication electricity water and sewage gas etc.) were contained many risks because of excavating. The exact position of underground facilities and the attribute information should be built in order to prevent accidents. As the result of analyzing the public surveying results from 2004 to 2009, it shows that low detecting rate of water pipeline which is only 52.4%, because the exploration of electromagnetic induction only detect metal pipeline and positioning survey only detect new pipeline before burying. Therefore development and verification of the correct and efficient exploration techniques are needed to improve the detecting rate. In this study, determined based on the location measurement results for the non-metal pipes and metal pipes before burial. It was compared with values that obtained through the ground penetrating radar and electromagnetic induction detecting. As a result, detecting rate of the concrete section showed a 100%, unpaved section showed a 94.7%, asphalt section showed 60%. So it confirmed the applicability of the ground penetrating radar at underground facilities detecting.