• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.609-612
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• 2001

To investigate the magnetic field distribution of power line, we used amorphous wire sensor. And we discuss extremely low frequency magnetic field distribution dependent upon arrangement of power line and shielding pipe made from iron or alumimum materials by both measurement and FEM(Finite Element Method) analysis. Appling current of single phase 60 [Hz] 15 [A] is supplied to copper wire coated enamel resign. As the results, we confirmed that linear characteristics of amorphous wire sensor is very excellent and measurement value agrees with FEM calculation. Magnetic field distribution due to shielding materials is changed by permeability and conductivity.

• 한국초전도ㆍ저온공학회논문지
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• 제22권4호
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• pp.1-5
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• 2020

Heart consists of myocardium cells and the electrophysiological activity of the cells generate magnetic fields. By measuring this magnetic field, magnetocardiogram (MCG), functional diagnosis of the heart diseases is possible. Since the strength of the MCG signals is weak, typically in the range of 1-10 pT, we need sensitive magnetic sensors. Conventionally, superconducting quantum interference devices (SQUID)s were used for the detection of MCG signals due to its superior sensitivity to other magnetic sensors. However, drawback of the SQUID is the need for regular refill of a cryogenic liquid, typically liquid helium for cooling low-temperature SQUIDs. Efforts to eliminate the need for the refill in the SQUID system have been done by using cryocooler-based conduction cooling or use of non-cryogenic sensors, or room-temperature sensors. Each sensor has advantage and disadvantage, in terms of magnetic field sensitivity and complexity of the system, and we review the recent trend of MCG technology.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.17-17
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• 2010

This paper address technical issues in calibrating discharge coefficients of sonic nozzles used to measure the volume flow rate of low vacuum dry pumps. The first challenging issue comes from the technical limit that their calibration results available from the flow measurement standard laboratories do not fully cover the low vacuum measurement range although the use of sonic nozzles for precision measurement of gas flow has been well established in NMIs. The second is to make an ultra low flow sonic nozzlesufficient to measure the throughput range of 0.01 mbar-l/s. Those small-sized sonic nozzles do not only achieve the noble stability and repeatability of gas flow but also minimize effects of the fluctuation of down stream pressures for the measurement of the volume flow rate of vacuum pumps. These distinctive properties of sonic nozzles are exploited to measure the pumping speed of low vacuum dry pumps widely used in the vacuum-related academic and industrial sectors. Sonic nozzles have been standard devices for measurement of steady state gas flow, as recommended in ISO 9300. This paper introduces two small-sized sonic nozzles of diameter 0.03 mm and 0.2 mm precisely machined according to ISO 9300. The constant volume flow meter (CVFM) readily set up in the Vacuum center of KRISS was used to calibrate the discharge coefficients of the machined nozzles. The calibration results were shown to determine them within the 3% measurement uncertainty. Calibrated sonic nozzles were found to be applicable for precision measurement of steady state gas flow in the vacuum process. Both calibrated sonic nozzles are demonstrated to provide the precision measurement of the volume flow rate of the dry vacuum pump within one percent difference in reference to CVFM. Calibrated sonic nozzles are applied to a new 'in-situ and in-field' equipment designed to measure the volume flow rate of low vacuum dry pumps in the semiconductor and flat display processes.

• Current Optics and Photonics
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• 제8권3호
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• pp.246-258
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• 2024

In aerospace and energy engineering, the reconstruction of three-dimensional (3D) temperature distributions is crucial. Traditional methods like algebraic iterative reconstruction and filtered back-projection depend on voxel division for resolution. Our algorithm, blending deep learning with computer graphics rendering, converts 2D projections into light rays for uniform sampling, using a fully connected neural network to depict the 3D temperature field. Although effective in capturing internal details, it demands multiple cameras for varied angle projections, increasing cost and computational needs. We assess the impact of camera number on reconstruction accuracy and efficiency, conducting butane-flame simulations with different camera setups (6 to 18 cameras). The results show improved accuracy with more cameras, with 12 cameras achieving optimal computational efficiency (1.263) and low error rates. Verification experiments with 9, 12, and 15 cameras, using thermocouples, confirm that the 12-camera setup as the best, balancing efficiency and accuracy. This offers a feasible, cost-effective solution for real-world applications like engine testing and environmental monitoring, improving accuracy and resource management in temperature measurement.

• Wind and Structures
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• 제20권3호
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• pp.469-488
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• 2015

A full-scale instrumented low-rise building with gable roof was built at a coastal site with a high incidence of tropical cyclones for monitoring of wind effects on the building during windstorms. This paper presents the field measurements of the wind velocity field around and the wind-induced pressures on the low-rise building during the passage of severe tropical storm Soudelor. Near-ground wind characteristics such as wind speed, wind direction, turbulence intensity, gust factor, turbulence integral length scale and wind velocity spectra were investigated. The wind-induced pressures on the roof of the building were analyzed and discussed. The results revealed that the eave and ridge edges on the roof were subjected to the most severe suction pressures under quartering winds. These suction pressures showed obvious non-Gaussian behavior. The measured results were compared with the provisions of ASCE 7-10 to assess the suitability of the code of practice for the wind-resistant design of low-rise buildings under tropical cyclones. The field study aims to provide useful information that can enhance our understanding of the extreme wind effects on low-rise buildings in an effort to reduce tropical cyclone wind damages to residential buildings.

• 한국자기학회지
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• 제12권4호
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• pp.149-153
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• 2002

지구자기장 이하의 저자기장 측정에 있어서 소형이고 소비전력이 작으면서 장기적 안정성이 요구되는 분야에 flux-gate 마그네토미터를 많이 사용하고 있다. 또한 많은 저자기장 측정분야가 지구자기장의 크기측정보다는 지자장의 변화를 측정하는 경우가 많기 때문에, 본 연구에서 측정범위가 $\pm$1,000 nT, 5pT/√Hz (at 1 Hz)인 flux-gate센서를 사용 $\pm$50000 nT인 지구자기장을 순차적 근사법으로 보상한 후 지구자기장의 변화를 고감도로 측정할 수 있는 3-축의 flux-gate 마그네토미터를 개발하였다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2007년도 춘계학술발표회 논문집
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• pp.73-76
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• 2007

The Global Positioning System(GPS)is an advanced navigation satellite system for determination to position. It can provide three-dimensional positioning, in dependent of weater, 24 hours per day. This paper described the Field DGPS program Using PDA can help a field work and compute the TM rectangular coordinates, compared the output of the Field DGPS program with the results of surveying using EDM(electronic distance measurement).

• 한국인터넷방송통신학회논문지
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• 제10권5호
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• pp.277-286
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• 2010

본 논문에서는 다가올 초고속 무선 서비스의 핵심 서비스 중의 하나로 부각되고 있는 UWB 무선통신 시스템에서 광대역 저출력 주파수 특성의 방사출력 측정방법에 대하여 연구하였다. UWB 시스템의 측정환경에서는 RMS 전계강도 측정, UWB PSD 측정, 검출 가능한 UWB 신호레벨, UWB 천이신호 수집 등에 대해서 언급하였다. 또한, CIDPR16-1에서 언급한 축력 측정법에 대해 분석하였으며 저 준위 e.i.r.p 복사 측정법에 대해 세부적으로 분석하였다. 마지막으로는 신호분석기를 이용하여 측정시의 고려사항에 대해 서술함으로써 UWB 시스템 상용화에 필요한 방사출력 측정에 필요한 내용을 마무리하였다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 1992년도 추계연구발표회 논문개요집
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• pp.22-23
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• 1992

• 한국전자통신학회논문지
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• 제14권1호
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• pp.265-274
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• 2019

본 논문은 저가형 AHRS(: Attitude Heading Reference System)센서를 이용하여 무인 운송체(Unmanned vehicle)의 자세를 무향 칼만 필터 (Unscented Kalman filter)통해 추정하는 방법을 제안한다. 측정된 가속도와 지구자기장 값을 이용하여 UKF의 보정 단계에서 사용될 자세를 계산한다. 롤 (roll)과 피치 (pitch)는 가속도로부터 구해지며 요 (yaw)는 지구 자기장을 이용하여 연산한다. 이때 사용되는 지구자기장 측정값은 강철 효과(hard-iron effect)와 연철 효과(soft-iron effect)에 의해 쉽게 왜곡되기 때문에 계산된 요의 불확실성이 롤이나 피치의 불확실성에 비하여 크다. 본 논문은 이러한 불확실성을 줄이기 위하여 측정된 지구자기장에 포함된 편차성분을 추정하고 보정하여 더 정밀한 요값을 구한다. 제안된 방법을 수조에서의 무인 운송체 항법 실험을 통하여 검증하였다. 실험결과, 자세 추정 성능이 개선되고 이에 따라 위치 추정 성능도 개선됨을 확인하였다.