• Journal of Navigation and Port Research
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• v.36 no.6
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• pp.429-435
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• 2012

Although GNSS hardware and software technologies have been steadily advanced, it is still difficult to obtain reliable positioning results in the area with lots of signal blockage. In this study, algorithms for integrated GPS and GLONASS double difference relative positioning were developed and its performance was validated via simulations of signal blockages. We assumed that signal blockages are caused by high-rise buildings to the east, west, and south directions. And then, GPS-only and integrated GPS/GLONASS positioning accuracy was analysed in terms of 2-dimensional positioning accuracies. Compared with GPS-only positioning, the positioning accuracy of integrated GPS/GLONASS improved by 0.3-13.5 meters.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2685-2686
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• 2004

심자도(Magnetocardiography: MCG)는 심장에서 발생하는 자기신호로 크기가 수 pico Tesla에서 수 femto Tesla 정도로 지구 자기에 비하여 $10^{-6}{\sim}10^{-10}$ 정도로 매우 작기 때문에 보통 3층의 차폐 막 구조로 되어 있는 자기차폐실을 사용하여 외부 잡음을 줄인다. 그러나 자기차폐실의 비용이 크기 때문에, 자기차폐실의 비용을 줄이고 다양한 신호처리를 병행하여 신호대 잡음비를 높이고 있다. 본 논문에서는 1Giga FLOPS (FLoating point Operationals Per Second)의 부동 소숫점 연산능력을 가진 TMS320C6701을 사용하여 실시간 신호처리가 가능한 신호처리 시스템을 설계하였다. 개발된 DSP 보드는 PCI-bus 기반으로 설계하여 신호 측정 컴퓨터에 내장이 가능하도록 하였다. 프로그램과 데이터 처리를 위한 외부 메모리를 장착하였고, PCI 콘트롤러를 갖추어 PC 와의 대용량 메모리 공유가 가능하도록 하였다. 제작된 DSP 보드를 사용하여, 심자도 신호에서 실시간으로 적응 잡음 소거 및 필터링을 구현하여 신호대 잡음비의 향상을 확인할 수 있었다.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.6
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• pp.650-657
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• 2001

This paper explains the process of designing a shielded encircling remote field eddy current (RFEC) probe to inspect nuclear fuel cladding tubes and investigates resulting signal characteristics. To force electromagnetic energy from exciter coil to penetrate into the tube, exciter coil is shielded outside by laminations of iron insulated electrically from each other. Effects of shielding and the proper operating frequency are studied by the finite element analysis and the location for sensor coil is decided. However, numerically simulated signals using the designed probe do not clearly show the defect indication when the sensor passes a defect and the other indication appeared as the exciter passes the defect is affected by the shape of shielding structure, which demonstrates that the sensor is directly affected by exciter fields. For this reason, the sensor is also shielded outside and this shielding dramatically improves signal characteristics. Numerical modeling with the finally designed probe shows very similar signal characteristics to those of inner diameter RFEC probe. That is, phase signals show almost equal sensitivity to inner diameter and outer diameter defects and the linear relationship between phase signal strength and defect depth is observed.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.5
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• pp.398-408
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• 2007

For better evaluation of material thickness by using the reflection type pulsed eddy current method, various probe models are designed and their response signals, characteristics, and sensitivities to thickness variation are investigated by a numerical analysis method. Since the sensor needs to detect magnetic fields from eddy currents induced in a test material, not from the exciter coil, two types of models that are shielded by the combination of copper and ferrite and only by ferrite are considered. By studying response signals from these shielded probe models, the peak value and the zero crossing time are selected as useful signal features for the evaluation of material thickness. Investigation of sensitivities of these two features shows that the sensitivity of peak value is more useful than that of zero crossing time and that the probe shielded only by ferrite gives much better sensitivity to thickness variation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.944-945
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• 2016

Gamma-ray Detector for gamma-ray imaging device is composed of a shielding body for shielding gamma-rays incident from the radiation source. Distribution of the gamma ray can be represented by the distribution information on the direction in which the detecting section and the signal through the incident hole of collimator. The role of the shield is important because all signals should be treated as noise except for the signal from the incident hole.In this paper In this paper, we have produced a compact, lightweight and Collimator shield by changing the structure and physical properties with respect to the collimator and shielding of lead-based gamma-ray detectors. And we analyzed the shielding effectiveness relative to the incident gamma ray sphere measured signal value through the gamma irradiation test facility. The results confirmed that the production and Collimator shielding the imaging device Implementing more efficient to implement.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.449-457
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• 2023

Shielding for reducing exposure dose can make the diagnosis limited. The purpose of this study is to increase the efficiency of radiation protection and minimize the loss of image information by producing the shielding made of the water and the contrast medium which has different proportion and finding out the ideal proportion of them. Each shielding materials were made of water and water-soluble iodine contrast medium with the different proportion. The attenuation rate of absorbed dose was evaluated by the shielding materials in the plastic contents for measuring the efficiency of the radiation protection. As a result, the higher ratio of the contrast medium, the more efficient it is for radiation attenuation. The anatomical structure was observed most properly in case of the solution with 20 ml of the contrast medium and most difficultly in case of more than 60 ml of the contrast medium. In case of the signal intensity between skeleton and gas, the difference of average value had a significant as p < 0.001. Shielding with contrast medium attenuates less than the conventional shielding but in the examination for the sensitive part to radiation, it can be used to minimize the loss of the image information and reduce the exposure dose.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2036-2037
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• 2007

반사형 펄스와전류(Pulsed Eddy Current; PEC) 탐상을 위한 여러 가지 탐촉자를 설계하고, 수치해석 방법을 사용하여 신호특성과 두께변화에 대한 만감도를 조사하였다. 구리와 페라이트를 차폐체로 사용한 결과, 구리로 차폐한 여자코일이 페라이트로 차폐한 센서코일보다 안쪽에 있는 것이 두께변화에 더 민감하였고, 페라이트만으로 차폐한 경우에도 여자코일이 안쪽에 있는 것이 더 민감하다는 것을 알 수 있었다. 한편, 두께가 두꺼워지면 펄스신호의 피크치는 감소하며 피크 발생시간이 변화하는 것을 관찰할 수 있었다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.464-469
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• 1996

차폐시설내에서 고방사성 물질이 이송되는 경우에 수송대상 핵물질의 이송경로를 감시하는 분석방법을 개발하였다. 이방법은 디지탈화하여 화상처리된 카메라 영상정보와 NDA 장비 및 NCC 프로그램에 의해 모니터링된 방사선 신호를 실시간으로 통합 분석하는 신경회로망 기법에 기초하고 있다. 핵물질의 경로와 핵물질의 종류 및 용기의 종류를 파악할 수 있는 이 방법은 정상적인 움직임과 비정상적인 움직임을 판단하여 차폐시설의 보장조치 체계를 구축할 수 있으며, DUPIC 핵연료 제조 시설 같은 새로운 시설의 보장조치 시스템의 일부로 활용될 수 있다.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.54-57
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• 1999

본 연구에서는 SQUID를 이용한 비파괴 평가 시스템을 제작, 측정하였다. 이 시스템은 비자기 차폐 환경에서 작동할 수 있도록 설계하였고, 측정 자기 센서로는 dc 및 rf-SQUID gradiometer를 사용하였다. 비자기 차폐 환경에서 ${\sim}$nT의 미세 자기 신호를 검출하였고, 공간적으로 변화하는 외부 자기 신호를 측정, 분석하였다. 또한, 측정된 자기 신호를 통해 dc-SQUID와 rf-SQUID에 대한 비교를 했다.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.6-11
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• 2013

In this paper, we explain the signal characteristics of HEMP and HEMP protection factors that affect the facilities are analyzed. We find the necessary elements of the physical facilities available for building. Shielding effects were measured by changing frequency and the distance of receiving antenna. Each measured value was compared to U.S. standard and measuring method was simplified. shielding effects were measured by three different conditions of shielding room. Find the difference between forward measurement and reverse measurement and factors which affects the measurement in shielding room.