• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.255-257
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• 2004

This paper was studied electromagnetic field distribution and damping of PD(Partial Discharge) signal in GIS(Gas Insulated Switchgear). Cut-off frequency of electromagnetic wave propagation modes were computed, electromagnetic field distribution of propagation modes in GIS by FEM(Finite Element Method) were simulated and simulated damping characteristic of electromagnetic waves in GIS by EMTP(Electromagnetic Transient Program) when generated PD pulse. Frequency band of $TE_{mn}/TM_{mn}$ modes were determinated by simulation results of electromagnetic field distribution and were discussed optimal position of UHF sensor from this results. Equivalent circuit was used to simulate signal damping of PD pulse in GIS by EMTP and compared with measured results in laboratory of KERI.

• Journal of the Ergonomics Society of Korea
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• v.28 no.3
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• pp.63-71
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• 2009

A car navigation system as an in-vehicle route guidance information (RGI) offers a state-of-the-art technological solution to driver navigation in an unfamiliar area. However, the RGI is provided by some pre-determined options in terms of the interface between a driver and a car navigation system. Drivers occasionally pass the target intersection owing to non- or late- recognizing it. This paper is examined the position of driver's turn signal operation and intersection recognition approaching at the target intersection which is difficult to identify, as a fundamental research on developing the additional RGI connecting with the turn signal control. The field experiment was conducted to measure distances of the turn signal operation and the intersection recognition from the target intersection according to left turns, right turns, and landmarks at adjacent intersection. And glance behavior to the car navigation display was evaluated by using an eye camera. The results of the field study indicate that, most case of driving, drivers operate the turn signal until 40m to 50m before coming to the target intersection. The driving simulator experiment was performed to examine the effectiveness of providing the additional RGI when drivers did not operate the turn signal approaching at the target intersection based on the results of the field study. To provide the additional RGI is effective for the intersection identification and recognition, and expected to improve the traffic safety and the comfort for drivers.

• Journal of radiological science and technology
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• v.46 no.2
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• pp.115-122
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• 2023

The purpose of this study was to examine the association between the shapes and colors of emergency exit symbols, magnetic field warning symbols, and radiation zone symbols used in hospitals for staff and patient safety and their effects on cognitive memory. The hippocampal region's signal intensity(SI) was analyzed using fMRI. The Symbol 2 (1.75±0.54) with a green background had the highest signal intensity (SI) for emergency exits, according to the findings. The black symbol 2 (1.60±0.51) with a yellow background had the highest signal intensity (SI) for the magnetic field warning symbol, followed by the black symbol 1 (1.59±0.65) with an orange background. The black symbol 2 (1.59±0.59) with a yellow background and the black symbol 3 (1.58±0.52) with an orange background had the low signal intensity with slight differences as for the radiation zone symbols. In conclusion, it was determined that the signal intensity of the black symbol with a yellow background was the highest in the magnetic field area and radiation area. This implies that symbols with a high signal intensity (SI) must be utilized intensively. To ensure that the correct meaning of the symbols is communicated in the future, they must also be utilized regularly and continually in disaster safety education.

• The Journal of the Acoustical Society of Korea
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• v.14 no.4
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• pp.96-99
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• 1995

Under signal range mismatch, the LCMV beamformer has the performance degradation to cancel a desired signal. Using the eigenstructure properties of the array covariance matrix, we investigate the cause of this problem. From this investigation, a robust beamformer to source range mismatch is presented. The proposed beamformer has the maximum output signal-to-noise ration (SNR). When a desired signal is in a far field, the weight vector of the proposed beamformer is not biased.

• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.24-28
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• 2007

Presuming that firing neurons have motions inside the MRI magnet due to the interaction between the neuronal magnetic field and the main magnetic field, we applied motion encoding gradients to dissected snail ganglia to observe faster responding MRI signal than the BOLD signal. To activate the snail ganglia in synchronization with the MRI pulse sequence, we used electrical stimulation with the frequency of 30 Hz and the pulse width of 2s. To observe the fast responding signal, we used the volume selected MRI sequence. The magnetic resonance signal intensity, measured with 8 ms long motion encoding gradient with a 20mT/m gradient strength, decreased about $3.46{\pm}1.48%$ when the ganglia were activated by the electrical stimulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8A
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• pp.618-631
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• 2012

In this paper polarization adaptivity on transmit has been used to enhance the received signals directed to a pre-selected receiver in a near-field multi-input multi-output (MIMO) environment. The objective here is to select a set of weights on the transmitting antennas adapted to individual receivers based on the principles of reciprocity. Using the polarization properties, when the number of receiving antennas is greater than the number of transmitting antennas, the transmitted signal may be directed more to a particular receiver location while simultaneously minimizing the reception signal strength at other receivers. Numerical simulations have been made to illustrate the novelty of the proposed approach.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.3
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• pp.395-400
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• 2013

In this paper, we introduce the implementation of high accurate level sensor system using the pulse wave type magnetostriction sensor. When a current pulse flows along the waveguide, the magnetic field also propagates towards the end of waveguide. When this magnetic field just passes the position of the magnet for level detection, the resultant magnetic field by these two magnetic fields makes a torsional reflected signal. This is used to calculate the time difference between a interrogation pulse wave and this torsional reflected signal. The key elements and characteristics were investigated to implement level sensor system based on this principle. We introduce a method to calculate the speed of ultrasonic reflected signal and how to make a model of sensing coil. In particular, we experiment with the characteristics of the torsional reflected signal according to the changes of the interrogation voltage and displacement. To make high accurate level sensor system, two methods were compared. One is to use the comparator and time counter, the other is STFT(Short Time FFT) which is capable of the time-frequency analysis.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.5
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• pp.338-344
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• 2000

This paper proposes a field-oriented control strategy without speed sensor in overall speed range. At low speed region including zero speed, the electrical saliency which is due to the main flux saturation is used in order to estimate an instantaneous flux position. This electrical saliency can be obtained from the difference of high frequency impedance by the high frequency signal injection. This method enables the stable operation at zero speed or stator frequency even under heavily loaded condition. However, because of the high frequency signal injection the loss and noise in motor increase and the voltage margin is reduced as the motor speed increases. Therefore, this algorithm must be supplemented with the algorithm based on the electrical model of motor, which is conventionally used in the region except the low speed. This paper proposes the combination algorithm between the high frequency signal infection method and the adaptive observer, in which the rotor flux and motor speed can be simultaneously estimated by the adaptive control theory. This combination algorithm enables the stable operation of field-oriented speed control without speed sensor in overall speed range. This is verified by experimental results.

• Journal of Magnetics
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• v.1 no.1
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• pp.14-18
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• 1996

The NMR spin echo in pure iron was measured as a function of external magnetic field up to 10 kgauss at room temperature. We observed the signal coming from a single domain formed over 7.5 kgauss which has not been detected in previous works. The resonance frequency shift with external field confirmed that the hyperfine field in iron is -330.2 kgauss. From the comparison of the magnetization curve with the domain wall signal and the resonance frequency in external field, we showed that NMR could give the useful qualitative information on the magnetization process. The extent of the internal strain removed by annealing, which can be hardly seen in hysteresis curves, was clearly shown up in the NMR line-width.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.199-202
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• 2002

This paper introduces the near field shading beamformer using widely known Chebyshev and Hanning window in the field of digital signal processing. The proposed shading beamformer improves the estimation of range as well as azimuth angle of targe residing in near field. A series of sensor weighting values are calculated from the FFT operation of given shading functions in time domain. This paper verifies the performance of the focused beamformer having the proposed shading sensor weights which are used to detect the range of target. Throughout computer simulations this paper exploits the performance improvement of the proposed shading beamformer as varying the frequency band of the received radiated signal along the non-uniform array.