• Title/Summary/Keyword: Ground Fault Detection

Search Result 74, Processing Time 0.02 seconds

Operational Concept Design and Verification for Airborne SAR System (항공탑재 SAR 시스템 운용개념 설계 및 검증)

  • Lee, Hyon-Ik;Kim, Se-Young;Jeon, Byeong-Tae;Sung, Jin-Bong
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.41 no.7
    • /
    • pp.588-595
    • /
    • 2013
  • Airborne SAR system is the imaging Radar system that is loaded on a manned or unmanned aircraft, which is in charge of high quality image acquisition and moving target detection. This paper describes the operational requirements for the Airborne SAR system and suggests the operational concept to satisfy the requirements. To be specific, it describes the interface with airborne system, state definition and transition, operation mode based on mission definition file, fault management, and data storing and transmission concept. Finally, it gives the ground test results to verify the SAR system operational concept.

Performance Improvement of the Wald Test for GPS RTK with the Assistance of INS

  • Abdel-Hafez, Mamoun F.;Kim, Dae-Je;Lee, Eun-Sung;Chun, Se-Bum;Lee, Young-Jae;Kang, Tae-Sam;Sung, Sang-Kyung
    • International Journal of Control, Automation, and Systems
    • /
    • v.6 no.4
    • /
    • pp.534-543
    • /
    • 2008
  • To use the Global Positioning System (GPS) carrier phase measurement for precise positioning, the integer ambiguities at the early stage of most algorithms must be determined. Furthermore, if a precise positioning is to be applied to real time navigation, fast determination and validation methods for integer ambiguity are essential. In this paper, the Wald test that simultaneously determines and validates integer ambiguities is used with assistance of the Inertial Navigation System (INS) to improve its performance. As the Wald test proceeds, it assigns a higher probability to the candidate that is considered to be true at each time step. The INS information is added during the Wald test process. Large performance improvements were achieved in convergence time as well as in requiring fewer observable GPS satellites. To test the performance improvement of the Wald test with the INS information, experimental tests were conducted using a ground vehicle. The vehicle moved in a prescribed trajectory and observed seven GPS satellites. To verify the effect of the INS information on the Wald test, the convergence times were compared with cases that considered the INS information and cases that did not consider the INS information. The results show that the benefits of using the INS were emphasized as fewer GPS satellites were observable. The performance improvement obtained by the proposed algorithm was shown through the fast convergence to the true hypothesis when using the INS measurements.

Shallow Gas Exploration in the Pohang Basin Transition Zone (포항분지 전이대에서 천부가스 탐사)

  • Lee, Donghoon;Kim, Byoung-Yeop;Kim, Ji-Soo;Jang, Seonghyung
    • Geophysics and Geophysical Exploration
    • /
    • v.25 no.1
    • /
    • pp.1-13
    • /
    • 2022
  • For surveying shallow gas reservoirs in the Pohang basin, we proposed a seismic exploration method applicable to the transition zone in which land and marine areas are connected. We designed the seismic acquisition geometry considering both environments. We installed land nodal receivers on the ground and employed vibroseis and airgun sources in both land and marine areas. For seismic exploration in the transition zone, specific acquisition and processing techniques are required to ensure precise matching of reflectors at the boundary between the onshore and offshore regions. To enhance the continuity of reflection events on the seismic section, we performed amplitude and phase corrections with respect to the source types and applied a static correction. Following these processing steps, we obtained a seismic section showing connected reflectors around the boundary in the transition zone. We anticipate that our proposed seismic exploration method can also be used for fault detection in the transition zone.

Two-Dimensional Interpretation of Ear-Remote Reference Magnetotelluric Data for Geothermal Application (심부 지열자원 개발을 위한 원거리 기준점 MT 탐사자료의 2차원 역산 해석)

  • Lee, Tae-Jong;Song, Yoon-Ho;Uchida, Toshihiro
    • Geophysics and Geophysical Exploration
    • /
    • v.8 no.2
    • /
    • pp.145-155
    • /
    • 2005
  • A two-dimensional (2-D) interpretation of MT data has been performed for the purpose of fracture detection for geothermal development. Remote stations have been operated in Kyushu, Japan (480 km apart) as well as in Korea (60 km and 165 km apart in 2002 and 2003 data set, respectively). Apparent resistivity and phase curves calculated by remote processing with the Japan remote data showed enough quality for 2-D inversion for the whole frequency range. Remote reference processing with Korea remote reference data also showed quite good continuity in apparent resistivity and phase curves except some noisy frequency bands; around the power frequency, 60 Hz, and around the dead band $10^{-1}Hz\;Hz\;\~1\;Hz$, where the natural EM signal is known to be very weak. Even though the subsurface showed severe three-dimensional (3-D) characteristics in the survey area so that 2-D inversion by itself could not give enough information for deep geological structures, the 2-D inversion for the 5 survey lines showed several common features. The conductive semi-consolidate mudstone layer is dipping from north to south (about 500 m depth on the south and 200 m on the north most part of the survey area). The boundary between the low (L-2) and high (H-2) resistivity anomalies can be thought as a major fault with strike $N15^{\circ}E$, passing through the sites 206, 112 and 414. The shallow (< 1 km) conductive anomalies (L-4) seem to be fracture zones having strike E-W (at site 105) and $N60^{\circ}W$ (at site 434). And there exists a conductive layer in the western and west-southern part of the survey area in the depth below $2\~3\;km$, for which further investigation is to be needed.