• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.6
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• pp.535-541
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• 2012

The three-down one-up method which is commonly used in the field of psychophysics is employed in this study that is to reveal how much magnitude of vibration makes discomfort in passenger vehicle on idle condition. Thirteen taxi drivers were invited for subject of the experiment where they evaluated the controlled vibrations on rigid seat in terms of idle vibration on passenger vehicle at frequency range from 15 Hz to 40 Hz. As the result, vibration of 100~105 dB is marginal range to make discomfort on passenger seat. Frequency dependency of the discomfort was found at the frequency range, which is the higher frequency the lower discomfort with the same magnitude of vibration. The frequency dependency found here was compared with ISO 2631-1 that is more sensitive at the frequency range.

• Journal of IKEEE
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• v.22 no.3
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• pp.599-604
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• 2018

A Stepped Frequency Radar(SFR) is a method that realizes high resolution range estimation by increasing the frequency of transmission pulses at regular intervals to generate a wide synthetic bandwidth. However, in the case of a moving target, accurate range estimation becomes difficult due to the range-Doppler coupling. In this paper, the process of high resolution range estimation by compensation of the range-Doppler coupling with estimated velocity of the moving target using the SFR waveform with Coherent Pulse Train(CPT) is analyzed and it was verified through simulation.

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1470-1476
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• 2019

The nuclear power plants in South Korea have been designed in accordance with the U.S. Regulatory Guide 1.60 (R.G 1.60) design spectrum of which the peak frequency range is 2-10 Hz. The characteristics of the earthquakes at the Korea nuclear power plant sites were observed to be closer to that of Central and Eastern United States (CEUS) than the R.G 1.60, which is a lower amplification in a low frequency range, and a higher amplification in a high frequency range. The possibility of failure for sensitive power plant components in the high frequency range has been considered and evaluated. In this study, in order to improve the reliability of nuclear plant and administrative control procedures, seismic tests of an emergency diesel generator (EDG) were conducted using a shaking table under both high and low frequency ranges. From the tests, oil/lubricant leaks from the bolt connections, the fuel filter and the fuel inlet were observed. Therefore, the check list of nuclear plant components after an earthquake should include bolt connections of EDG as well as anchor bolts.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.8
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• pp.64-72
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• 2010

This paper presents a wide range VCO with fine coarse tuning step using a sigma-delta modulation technique for UWB frequency synthesizer. The proposed coarse tuning scheme provides the low effective frequency resolution without any degradation of phase noise performance. With three steps coarse tuning, the VCO has wide tuning range and fine tuning step simultaneously. The frequency synthesizer with VCO was implemented with 0.13 ${\mu}m$ CMOS technology. The tuning range of the VCO is 5.8 GHz~6.8 GHz with the effective frequency resolution of 3.9 kHz. It achieves the measured phase noise of -108 dBc/Hz at 1 MHz offset and a tuning range 16.8 % with 5.9 mW power. The figure-of-merit with the tuning range is -181.5 dBc/Hz.

• Journal of Biomedical Engineering Research
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• v.36 no.3
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• pp.69-78
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• 2015

Ultrasonic physiotherapy systems should comply with IEC 60601-2-5(particular requirements for safety of ultrasonic physiotherapy equipment) standard for safety of patients and clinical performances. One of the most important parameters in the standard is the effective radiating area ($A_{ER}$). It has to be measured in accordance with IEC 61689 (field specifications and methods of measurement in the frequency range 0.5MHz to 5MHz). Typical ultrasonic physiotherapy system works in the frequency range 1MHz ~ 3MHz to comply with the IEC 61689. However, ultrasonic physiotherapy system using frequencies over 5MHz is out of the IEC 61689's scope. That is, even if such ultrasonic physiotherapy systems are developed by demands of the market, there is no standard to apply. It is the motivation for this study. Whereas there are other parameters to be considered, this study focuses on the effective radiating area and shows effectiveness of applying IEC 61689 in measuring effective radiating area of ultrasonic physiotherapy systems using frequency range over 5MHz by comparing the results of computer simulation and experiment. Results of this study shows that applying the IEC 61689 standard to ultrasonic physiotherapy system using frequency range over 5MHz is possible.

• The Journal of Korean Physical Therapy
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• v.13 no.3
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• pp.719-726
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• 2001

Transdermal drug delivery offers various advantages over conventional drug delivery systems, such as avoidance gastrointestinal degradation and hepatic first-pass effect. encourages patient compliance. and possible sustained release of drugs. However, transdermal transport of drugs is low permeability of the stratum corneum, the superficial layer of the skin. Many physicochemical and biological factors influencing transdermal transport is described together with the corresponding experimental and clinical results. Phonophoresis is medical treatment with drugs introduced into the skin by ultrasound energy. Enhanced drug penetration is through to result from the biophysical alterations of skin structure by ultrasound waves. The frequency used for phonophoresis is usually from 20 kHz to 15MHz. Phonophoresis can be categorized in to three ranges: low-frequency range(below 1 MHz). therapeutic frequency range(1 to 3MHz), and high-frequency range(above 3 MHz). The depth of penetration of ultrasound into skin is inversely proportional to the frequency. Cavitation may cause mechanical stress. temperature elevation, or enhanced chemical reactivity causing drug transport. One theory is that ultrasound affects the permeation of the stratum corneum lipid structure as the limiting step in permeating through the skin. The range of indications for phonophoresis is wide. Aspecific classification of the range of indications is obtained by classification of pathological conditions. The continuous research is needed for many interesting issucs of phonophoretic transdermal delivory in new future.

• Journal of Power Electronics
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• v.15 no.4
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• pp.861-875
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• 2015

This paper presents a wide frequency range LLC resonant controller IC for LED backlight units. In this paper a new phase-domain resonance deviation prevention circuit (RDPC), which covers a wide frequency and input voltage range, is proposed. In addition, a wide range gate clock generator and an automatic dead time generator are proposed. The chip is fabricated using 0.35 μm BCD technology. The die size is 2 x 2 mm2. The frequency of the clock generator ranges from 38 kHz to 400 kHz, and the dead time ranges from 300 ns to 2 μs. The current consumption of the LLC resonant controller IC is 4 mA for a 100 kHz operation frequency using a supply voltage of 15 V.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.3
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• pp.46-57
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• 1995

The aim of the present study is to provide fundamental informations for the development of magneticfluid actuator. To achieve the aim, oscillation characteristics of the magneticfluid plug are investigated by experiment for the various length and position of the magneticfluid plug and the frequency of magnetic field. The oscillation characteristics are obtained. Amplitude, natural frequency, phase shift and damping ratio, are compared with theoretical values. From the study, the following conclusive remarks can be made. The experimental equation for the magnetic field is obtained. The critical magneticfluid length exists and its value is about 70mm. The range of the damping ratio and fluid loss coefficient obtained by experiment are 0.1~0.2 and 30~100, respectively. Comparison between experimental and theoretical results of oscillation characteristics shows good agreement in the high frequency range. Meanwhile, in the low frequency range, there appears little discrepancies(5% in the frequency and amplitude and 10% in phase difference and damping ratio) with each other.

• Journal of Mechanical Science and Technology
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• v.15 no.2
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• pp.232-238
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• 2001

Fast Fourier Transformation is employed to convert the head variation of a pipeline in the time domain to the amplitude of the frequency domain. Applying method of characteristics to a pipeline provides a significant frequency range for a surge introduced from the valve modulation. Inverse Fast Fourier Transformation and a Finite Impulse Response Filter can be used to remove any possible noise existing from the significant frequency range of an unsteady condition. A filtered signal shows higher potential for the inverse calculation of leakage detection than the noise-added signal does. The respective performances of Inverse Fast Fourier Transformation and a Finite Impulse Response Filter are compared in terms of leakage detection capability. Characteristics of the frequency range for multiple leakages were investigated to validate the effectiveness of the noise control method in the frequency domain.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1091-1098
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• 2012

This paper describes frequency response and propagation characteristics considering semiconducting screen in distribution cables. In CIGRE WG 21-05, Simplified Approach(SA) and Rigorous Approach(RA) which can revise the permittivity considering semiconducting screen propose for more detailed EMTP model and frequency dependant analysis. In this paper, the frequency dependent characteristics of complex permittivity are variously analysed by cole-cole function of RA. The attenuation, propagation velocity and surge impedance according to frequency range(1 kHz to 500 MHz) and cable length are also analysed by SA and EMTP simulation in distribution cables. The propagation velocity considering semiconducting screen is slower, and it is saturated over the range of 1 MHz. The signal is significantly attenuated as frequency range is high.