• 로봇학회논문지
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• 제5권4호
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• pp.294-301
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• 2010

In order to produce a convenient robot for the aged and the lower limb disabled, it is needed for the research detecting implicit walking intention and controlling robot by a user's intention. In this study, we developed sensor module system to control the walking- assist robot using FSR sensor and tilt sensor, and analyzed the signals being acquired from two sensors. The sensor module system consisted of the assist device control unit, communication unit by wire/wireless, information collection unit, information operation unit, and information processing PC which handles integrated processing of assist device control. The FSR sensors attached user's the palm and the soles of foot are sensing force/pressure signals from these areas and are used for detecting the walking intention and states. The tilt sensor acquires roll and pitch signal from area of vertebrae lumbales and reflects the pose of the upper limb. We could recognize the more detailed user's walking intention such as 'start walking', 'start of right or left foot forward', and 'stop walking' by the combination of FSR and tilt signals can recognize.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.161-166
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• 2006

A new fiber orientation sensor has been developed and tested on an actual paper machine to demonstrate its capability to function as a real-time monitoring system. First, we demonstrate the ability of the sensor system to detect the change in the fiber orientation angle while the sensor head, and not the paper, was intentionally rotated from $-90^{\circ}\;to\;+70^{\circ}$ with respect to the paper-traveling direction. Next, we demonstrate that this system can successfully detect the change in the magnitude and angle of fiber orientation in running paper when the direction of material flow on the wire was changed on the paper machine. The angle and magnitude of fiber orientation were independently confirmed by SST and MOA measurements. Furthermore, we found that the system was capable of measuring the basis weight and the moisture content of running paper while detecting the angle and magnitude of fiber orientation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.232-235
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• 2000

Design and experiments of a nondestructive system to inspect deterioration of ACSR-OC (ACSR Outdoor Cross-linked Polyethylene Insulated Wire usually used in HV overhead distribution lines presented in this paper. ACSR-OC conductor built to pollutants air for a long period would be easily progress to corrode so that it may lead to the reduction of the effective cross section area of conductors. A fault diagnosis system consisting of a solenoid sensor, a constant current source with RF frequency signal processing unit and a motor driver/controller designed and implemented. This instrument can dot the sensor output variation due to deterioration corrosion, continuously. As a result, it was shown such corrosion detector can readily be utilized estimating the diameter change due to deterioration overhead distribution lines and in giving an warning or inform before severe aged conductor lead to fail.

• 전기학회논문지
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• 제57권2호
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• pp.268-275
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• 2008

In this paper, we introduce a new method for detecting and estimating faults on a power line using the time-frequency domain reflectometry system. The system rests upon time-frequency signal analysis and uses a chirp signal which is multiplied by Gaussian envelope. The chirp signal is used as a reference signal, and we can get the reflected signal from a fault on a wire. To detect and estimate faults, we analyze the reflected signal by Wigner time-frequency distribution function and normalized time-frequency cross correlation function. In this paper we design an optimal reference signal for power line and implement a system for estimating fault distance on a power line with the TFDR implemented by PXI equipments. This approach is verified by some experiments with HIV 2.25mm power lines.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.158-159
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• 2006

The system measuring the Partial discharge(PD) is very essential to investigate the hazard defects in the insulation systems of the high voltage engineering. We included two parts in this discussion; The proposed method of Foil Sensor Array and the normally used method m the practice. Firstly, it will be shown the improved sensitivity of our proposed FSA sensor compare with the existing normal foil sensor. And then, the linearity of detecting sensitivities of various kinds of FSA sensors such as $2{\times}2$, $2{\times}4$, $3{\times}3$ etc. using in our experiments, was shown. From the obtained results, we can see that FSA sensor is more sensitivity than normal foil sensor and the linear increment property of FSA sensitivities.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1174-1180
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• 2015

We investigate in this paper the radiated electromagnetic waves together with the discharge characteristics of Trichel pulse of negative DC corona discharge in air in pin-to-plate and wire-to-plate configurations. The feature of the current pulse and the frequency spectrum of the electromagnetic radiations were measured under various pressures and gas gaps. The results show that the repetition frequency and the amplitude of Trichel pulse current depend on the discharge conditions, but the rising time of the pulse relates only to the radius of needle or wire and keeps constant even if the other conditions (including the discharge current, the gas gap and the gas pressure) change. There exists the characterized spectrum of electromagnetic waves from negative corona discharge in Trichel pulse regime. These characterized radiations do not change their frequency at a given cathode geometry even if the averaged current, the gas gap or the air pressure changes, but the amplitude of radiations changes accordingly. The characterized electromagnetic radiations from Trichel pulse corona relate to the formation or the rising edge of current pulse. It confirms that the characterized radiations from Trichel pulse supply information of discharge system and provide a potential method for detecting charged targets.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.2112-2113
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• 2008

The concept is based on distributed wireless sensors that are attached to the incoming and outgoing power lines of secondary substations. A sensor measures only phase current characteristics of the wire it is attached to, is not synchronized to other sensors and does not need configuration of triggering levels. The main novelty of the concept is in detecting and locating faults by combining power distribution network characteristics on system level with low power sampling methods for individual sensors. This concept enables the sensor design to be simple, energy efficient and thus applicable in new installations and for retrofit purposes in both overhead and underground electrical distribution systems.

• Tribology and Lubricants
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• 제29권3호
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• pp.143-148
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• 2013

In this study, several sensor parts used to obtain better signal stability are designed, a separate control circuit for the sensor is developed, and the results obtained using this control circuit are analyzed. The capacitances of the whole sensor system are measured using the control circuit connected to an improved flexible printed circuit board and an asymmetric dual sensor coated with a ceramic material. To realize good discrimination for a small change in the measured capacitance as the engine oil deteriorates, a commercial application-specific integrated circuit is installed on the control circuit as a capacitance-to-digital converter. The absolute error of a measured signal is found to be approximately ${\pm}4fF$.

• 전기전자학회논문지
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• 제25권4호
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• pp.689-696
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• 2021

본 논문에서는 고장예측진단 및 건전성 관리 기법(Prognostics and Health Management, PHM)을 적용하기 위해 해당 시스템 혹은 회로 내부에서 결함특성을 감지하고 예측할 수 있는 회로 구조를 제안하였다. 기존 연구에서 회로 결함의 진행에 따라, S-parameter 크기 최소값의 주파수가 변화하는 것을 확인하였다. 이러한 특성을 기존에는 네트워크 분석기(Network Analyzer)를 활용하여 측정하였으나, 본 연구에서는 같은 결함검출기법을 활용하더라도 큰 계측장비 없이 결함의 진행상황 및 잔여 수명, 결함발생 여부를 확인할 수 있는 소형화된 회로를 설계하였다. 본 연구에서는 S-parameter의 변화를 야기하는 임피던스의 변화를 감지할 수 있도록 회로를 설계하였으며, Bond-wire의 온도반복에 따른 S-parameter 변화 측정결과를 제안하는 회로에 적용하였다. 이를 통해 해당 회로가 Bond-wire의 결함을 감지할 수 있다는 것을 성공적으로 검증하였다.

• Progress in Superconductivity
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• 제10권2호
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• pp.139-143
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• 2009

We have fabricated a low-noise 61-channel axial-type first-order gradiometer system for measuring fetal magnetocardiography(MCG) signals. Superconducting quantum interference device(SQUID) sensor was based on double relaxation oscillation SQUID(DROS) for detecting biomagnetic signal, such as MCG, magnetoencphalogram(MEG) and fetal-MCG. The SQUID sensor detected axial component of fetal MCG signal. The pickup coil of SQUID sensor was wound with 120 ${\mu}m$ NbTi wire on bobbin(20 mm diameter) and was a first-order gradiometer to reject the environment noise. The sensors have low white noise of 3 $fT/Hz^{1/2}$ at 100 Hz on average. The fetal MCG was measured from $24{\sim}36$ weeks fetus in a magnetically shielded room(MSR) with shielding factor of 35 dB at 0.1 Hz and 80 dB at 100 Hz(comparatively mild shielding). The MCG signal contained maternal and fetal MCG. Fetal MCG could be distinguished relatively easily from maternal MCG by using independent component analysis(ICA) filter. In addition, we could observe T peak as well as QRS wave, respectively. It will be useful in detecting fetal cardiac diseases.