• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.52-55
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• 1996

This paper describes the bending traveling-wave type ultrasonic motor which generates the traveling wave by combining two standing waves with phase difference time and space. In $+20^{\circ}C$~$30^{\circ}C$, the USM motor operation character has represented normal condition. But the other temperature, (that is say, when long time operating condition) USM operation characteristic has abnormal condition, that is driving frequency, drive current and r.p.m is down. The recent USM has controller without temperature compensation. This study aimed at fuzzy controller which must follow the phase angle difference 90$^{\circ}$at operation temperature and them r.p.m and torque increase.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.441-444
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• 1997

This paper describes the bending traveling-wave type ultrasonic motor which generates the traveling wave by combining two standing waves with phase difference time and space. In +2$0^{\circ}C$~3$0^{\circ}C$, the operation characteristic of USM has represented normal condition. But in the other temperature, the operation characteristic of USM has abnormal condition, that is driving frequency, drive current and r.p.m are down. The recent USM has controller without temperature compensation. This study aimed at fuzzy controller which must follow the frequency at operation temperature and then r.p.m and torque increased.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1603-1608
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• 2003

The Present Study reported on the experimental and numerical results of heat transfer in the acoustic fields induced by ultrasonic waves. The strong upwards flow called as acoustic streaming was visualized by a particle image velocimetry (P.I.V). in addition, the augmentation of heat transfer was experimentally investigated in the presence of acoustic streaming and was compared with the profiles of acoustic pressure calculated by the numerical analysis. Experimental and numerical studies clearly show that acoustic pressure variations are closely related to the augmentation of heat transfer.

• Progress in Superconductivity
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• v.11 no.2
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• pp.147-151
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• 2010

We have developed a high-$T_c$ SQUID magnetocardiogram (MCG) system for small laboratory animals. White noise of the measurement system was about 30 fT/$Hz^{1/2}$ when measured in a magnetically shielded room. We optimized the measurement position to obtain clear MCG wave from rat's small heart by using grid measurements. With the optimization, the MCG signal was successfully detected with the peak amplitude of about 30 pT. We could observe well defined P-, QRS-, and T-waves from the rat MCG. The results suggest that the developed system has a strong potential to monitor the progress of the heart disease model by using a laboratory rat.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.746-749
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• 1988

This paper describes an arrhythmia detection algorithm using PP and PR Interval. In order to detect P-wave accurately, an improved 5-point derivative method is used. In this paper, the RR, PP and PR interval. and the number of P-waves per RR Interval are detected for arrhythmia detection. These parameters can be utilized to diagnose in the varied types of AV block, atrial fibrillation, and PVC.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.313-320
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• 2002

In accordance with the need of developing a methodology for the sludge reduction, this study investigates the effect of sonication on the dewaterability of the sewage sludge. The investigation involves laboratory experiments of the sewage sludge from Yongin Waste Treatment Plant. The Laboratory tests were conducted under a broad range of conditions including energy levels of ultrasonic waves, time for the treatment, pH, and effect of polymers. The results of the study show that sonication enhances the dewaterability significantly The degree of enhancement varies with sonication power, treatment time, the amount of sludge treated. The effect of sonication on the temperature and pH of the test specimens seems not to be significant. The polymer can be useful to enhance the effectiveness of ultrasound treatment.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.28-30
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• 2002

The PD in GIS leads to a charge transfer and a voltage drop across the discharge area. They cannot be measure directly but we can measure electromagnetic wave made by PD. In generally, compared with VHF band, electromagnetic waves of UHF band have a low noise therefore, we can detect the real defect with several pC in GIS using UHF method. In this paper, the U-slot microstrip patch antenna for measuring PD signal in GIS is presented. the proposed UHF sensor are designed to have large band characteristics and unaffected structure for GIS operation.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.1
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• pp.13-24
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• 2013

Various elastic wave-based site investigation methods have been used to characterize subsurface ground because the dynamic properties can be correlated with various geotechnical parameters. Although the inherent spatial variability of the geotechnical parameters affects the P-wave propagation characteristics, ground heterogeneity has not been considered as an influential factor. Thus, the effect of heterogeneous ground on the travel-time shift and wavefront characteristics of elastic waves through stochastic numerical analyses is investigated in this study. The effects of the relative correlation lengths and relative propagation distances on the travel-time shift of P-waves considering various intensities of ground heterogeneity were investigated. Heterogeneous ground fields of stiffness (e.g., the coefficient of variation = 10 ~ 40%) were repeatedly realized in numerical finite difference grids using the turning band method. Monte Carlo simulations were undertaken to simulate P-wave propagation in heterogeneous ground using a finite difference method-based numerical approach. The results show that the disturbance of the wavefront becomes more significant with stronger heterogeneity and induces travel-time delays. The relative correlation lengths and propagation distances are systematically related to the travel-time shift.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.5
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• pp.480-485
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• 1998

Application of trans rectal ultrasonography to buffaloes (n=6) to follow the growth of large antral follicles individually, on each day of one interovulatory interval revealed that follicular turnover during oestrous cycle occured in waves. There was a predominance of a two-wave pattern (5/6 animals) compared to that of a three-wave pattern (1/6 animals). For two-wave pattern, the first wave emerged at Day $0.20{\pm}0.19$ (Day 0 = day of ovulation) and was marked by development of a dominant anovulatory follicle which grew in size from $5.40{\pm}0.24mm$ at the day of detection to a maximum diameter of $12.40{\pm}0.81mm$ on Day $8.60{\pm}1.57$, with a growth rate of $0.88{\pm}0.17mm/day$ and then regressed, with a mean persistence of $19.40{\pm}1.54$ days. The second wave emerged at Day $9.20{\pm}1.06$ and was marked by development of a dominant ovulatory follicle which grew in size from $4.20{\pm}0.37mm$ at the day of detection to a maximum diameter of $13.80{\pm}0.37mm$ on Day $21.00{\pm}1.38$, with a growth rate of $0.66{\pm}0.12mm/day$ and then ovulated on Day $21.60{\pm}1.25$, with a mean persistence of $11.80{\pm}1.39$ days. The maximum diameters attained and the growth rates of dominant anovulatory and dominant ovulatory follicles, and the mean number of follicles ${\geq}3mm$ diameter detected at the time of emergence of first and second waves ($11.80{\pm}1.74$ and $9.00{\pm}2.81$, respectively) were not significantly different. In the animal which showed a three-wave pattern, the first, second and third waves emerged on Days 1, 10 and 19, respectively. All animals, except one had at least one subordinate follicle in the first or second or both waves. The subordinate follicles increased in diameter over a few days and then regressed. The results indicate that in buffaloes, the follicular turnover during oestrous cycle occurs predominantly in a two-wave pattern.

• Journal of Information Processing Systems
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• v.11 no.3
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• pp.465-482
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• 2015

IEEE 802.11p is a standard MAC protocol for wireless access in vehicular environments (WAVEs). If a packet collision happens when a safety message is sent out, IEEE 802.11p chooses a random back-off counter value in a fixed-size contention window. However, depending on the random choice of back-off counter value, it is still possible that less important messages are sent out first while more important messages are delayed longer until sent out. In this paper, we present a new scheme for safety message scheduling, called the enhanced message priority mechanism (EMPM). It consists of the following two components: the benefit-value algorithm, which calculates the priority of the messages depending on the speed, deceleration, and message lifetime; and the back-off counter selection algorithm, which chooses the non-uniform back-off counter value in order to reduce the collision probability and to enhance the throughput of the highly beneficial messages. Numerical results show that the EMPM can significantly improve the throughput and delay of messages with high benefits when compared with existing MAC protocols. Consequently, the EMPM can provide better QoS support for the more important and urgent messages.