• Title/Summary/Keyword: Frequency Deviation

Search Result 1,417, Processing Time 0.024 seconds

Assessing Methods of Heart Rate Variability (심박변이에 대한 평가방법)

  • Park, Ki-Jong;Jeong, Heejeong
    • Annals of Clinical Neurophysiology
    • /
    • v.16 no.2
    • /
    • pp.49-54
    • /
    • 2014
  • Heart rate variability is significantly associated with cardiovascular complications in various neurological disorders with cardiac impairment. Measures of spontaneous heart rate variability might be different from provocating tests of heart rate variability such as deep breathing and Valsava maneuver. Methods for analysis are divided into time domain methods and frequency domain methods. There are standard deviation of NN interval, standard deviation of average NN interval, root mean square of the successive differences, NN50, and pNN50 in time domain methods. Frequency domain bands can be divided into very low, low, and high frequency. Each variables are influenced by sympathetic and/or parasympathetic activity.

Performance Verification of Anti-Islanding of Reactive Power Variation Method using Positive Feedback (정궤환을 이용한 무효전력 변동기반의 단독운전 방지 성능 검증)

  • Jo, Jongmin;Shin, Chang-Hoon;Cha, Hanju
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.24 no.2
    • /
    • pp.105-110
    • /
    • 2019
  • This study proposed a reactive power variation (RPV) method equipped with positive feedback (PF) for detecting the islanding operation of distributed generation systems. The proposed RPV consists of the constant reactive power component and a certain reactive power term and uses the frequency deviation between the rated and the measured frequencies. The constant reactive power is injected from distributed generation system and power factor is to 0.9975 in grid-connected operation. PF is activated from generation of the frequency deviation and the injected reactive power is continuously increased due to PF when islanding occurs. Consequently, the increasing reactive power causes the point of common coupling frequency to deviate from the maximum/minimum threshold level. Performance of the proposed RPV is verified in a 1.7 kW T-type inverter, and the detection times are 53 and 150 ms.

A Biomolecular Sensing Platform Using RF Active System

  • Kim, Sang-Gyu;Lee, Hee-Jo;Yook, Jong-Gwan
    • Journal of electromagnetic engineering and science
    • /
    • v.12 no.4
    • /
    • pp.227-233
    • /
    • 2012
  • This paper describes a novel and compact biosensing platform using an RF active system. The proposed sensing system is based on the oscillation frequency deviation due to the biomolecular binding mechanism on a resonator. The impedance variation of the resonator, which is caused by a specific biomolecular interaction results in a corresponding change in the oscillation frequency of the oscillator so that this change is used for the discrimination of the biomolecular binding, along with concentration variation. Also, a Surface Acoustic Wave (SAW) filter is utilized in order to enhance the biosensing performance of our system. Because the oscillator operates at the skirt frequency range of the SAW filter, a small amount of oscillation frequency deviation is transformed into a large variation in the output amplitude. Next, a power detector is used to detect the amplitude variation and convert it to DC voltage. It was also found that the frequency response of the biosensing system changes linearly with three streptavidin concentrations. Therefore, we expect that the proposed RF biosensing system can be applied to bio/medical applications capable of detecting a nano-sized biomolecular interaction.

Power Smoothing of a Variable-Speed Wind Turbine Generator Based on the Rotor Speed-Dependent Gain (회전자 속도에 따라 변하는 게인에 기반한 가변속 풍력발전기 출력 평활화)

  • Kim, Yeonhee;Kang, Yong Cheol
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.65 no.4
    • /
    • pp.533-538
    • /
    • 2016
  • In a power grid that has a high penetration of wind power, the highly-fluctuating output power of wind turbine generators (WTGs) adversely impacts the power quality in terms of the system frequency. This paper proposes a power smoothing scheme of a variable-speed WTG that can smooth its fluctuating output power caused by varying wind speeds, thereby improving system frequency regulation. To achieve this, an additional loop relying on the frequency deviation that operates in association with the maximum power point tracking control loop, is proposed; its control gain is modified with the rotor speed. For a low rotor speed, to ensure the stable operation of a WTG, the gain is set to be proportional to the square of the rotor speed. For a high rotor speed, to improve the power smoothing capability, the control gain is set to be proportional to the cube of the rotor speed. The performance of the proposed scheme is investigated under varying wind speeds for the IEEE 14-bus system using an EMTP-RV simulator. The simulation results indicate that the proposed scheme can mitigate the output power fluctuation of WTGs caused by varying wind speeds by adjusting the control gain depending on the rotor speed, thereby supporting system frequency regulation.

Proposition to Natural Frequency of Liquid Column Vibration Absorber with Vertical-Horizontal Area Ratio (수직-수평부 단면적비에 따른 동조액체기둥형 감쇠장치의 고유진동수 산정식 제안)

  • Woo, Sung-Sik;Lee, Sang-Hyun;Chung, Lan;Lee, Joung-Woo;Cho, Seung-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2008.04a
    • /
    • pp.653-658
    • /
    • 2008
  • LCVA has an advantage that its natural frequency can be easily controlled by changing the area ratio of the vertical column and horizontal part. The previous studies investigated the dynamic characteristics of the LCVA under harmonic load. This study experimentally obtained the first and second mode natural frequencies of the LCVA from shaking table tests using white noise and compared the values with the ones by previous study. Test results show that the measured first mode natural frequency of the LCVA has a different value compared with calculated one. The effective length($L_e$) was revised using by power equation. In the Case01 to 19, the standard deviation($s_r$) is 4.7292 and the coefficient of correlation(r) is 0.9856. In the Case21 to 61, the standard deviation ($s_r$) is 14.2143 and the coefficient of correlation(r) is 0.9935. The second mode frequency increases with the increasing area ratio, which is due to the sloshing motion effect resulting from the large area of the vertical column.

  • PDF

Proposition to Natural Frequency of Liquid Column Vibration Absorber with Vertical-horizontal Area Ratio (수직-수평부 단면적비에 따른 동조액체기둥형 감쇠장치의 고유진동수 산정식 제안)

  • Woo, Sung-Sik;Chung, Lan;Lee, Joung-Woo
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.19 no.2
    • /
    • pp.119-126
    • /
    • 2009
  • LCVA has an advantage that its natural frequency can be easily controlled by changing the area ratio of the vertical column and horizontal part. The previous studies investigated the dynamic characteristics of the LCVA under harmonic load. This study experimentally obtained the first and second mode natural frequencies of the LCVA from shaking table tests using white noise and compared the values with the ones by previous study. Test results show that the measured first mode natural frequency of the LCVA has a different value compared with calculated one. The effective length($L_e$) was revised using by power equation. In the case01 to 19, the standard deviation($S_r$) is 4.7292 and the coefficient of correlation(r) is 0.9856. In the case21 to 61, the standard deviation($S_r$) is 14.2143 and the coefficient of correlation(r) is 0.9935. The second mode frequency increases with the increasing area ratio, which is due to the sloshing motion effect resulting from the large area of the vertical column.

Cancellation of AltBOC Correlation Side-Peaks for Frequency Sharing in Satellite Communication Spectrum (위성통신대역 주파수 공유를 위한 AltBOC 상관 내 주변 첨두 제거 기법)

  • Chae, Keunhong;Yoon, Seokho
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.39B no.11
    • /
    • pp.810-816
    • /
    • 2014
  • The alternative binary offset carrier (AltBOC) signal shares frequency spectrum with the phase shift keying (PSK) signal, enabling us to manage the satellite communication spectrum more efficiently. However, the side-peaks in the AltBOC autocorrelation pose an ambiguity in the AltBOC signal tracking, and consequently, makes the frequency sharing via the AltBOC difficult. Therefore, in this paper, we propose a cancellation scheme of the AltBOC correlation side-peaks. From the numerical results, it is confirmed that the proposed scheme removes the ambiguity in signal tracking caused by the side-peaks completely, and thus, has a much lower tracking error standard deviation (TESD) (i.e., a much better tracking performance) than the conventional scheme.

Heart Response Effect by 1/f Fluctuation Sounds for Emotional Labor on Employee (1/f 수준 별 음악 자극이 감정 노동 종사자의 심장 반응에 미치는 효과)

  • Jeon, Byung-Mu;Whang, Min-Cheol
    • Science of Emotion and Sensibility
    • /
    • v.18 no.3
    • /
    • pp.63-70
    • /
    • 2015
  • This study identified heart response of participants while listening to sounds which have 1/f fluctuations with exponent ${\alpha}$ gradient. The participants were engaged in emotional stress work. Prior studies related to 1/f fluctuation sound have reported that sound source can alleviate psychological and physiological state of users. Subjects of this study were exposed to sound with three levels of ${\alpha}$ gradient. Heart response of subjects were measured with Photoplethysmography(PPG) sensor simultaneously. The dependent variables of this study were beat per minute(BPM), very low frequency percent of pulse rate variability (VLF percent), the standard deviation of all normal RR intervals (SDNN), and high frequency power(HF power). Subject showed arousal response when exposed to sound with exponent ${\alpha}$ gradient of 3 whereas the sound with exponent ${\alpha}$ gradient of 1 and 2 resulted in relax effect. The characteristic of 1/f fluctuation sounds can be applied to alleviate stress for employers under emotional labor.

VIBRATION OF A CIRCULAR PLATE WITH A CONCENTRATED MASS ATTACHED ON A RADIUS

  • Lee, Jang-Moo;Hong, Jin-Sun
    • Journal of Theoretical and Applied Mechanics
    • /
    • v.1 no.1
    • /
    • pp.89-96
    • /
    • 1995
  • An analytical method is presented for predicting the effect of a local deviation in the form of a concentrated mass along a radial line on the free bending vibration characteristics of a nearly axisymmetric circular plate. The approach is based on the Rayleigh-Ritz method and the expression of local deviation of the concentrated radial mass as the variation of heaviside unit step function. The effects of the concentrated mass on the natural frequencies and mode shapes of the plate are predicted with a proposed nondimensional mass parameter.

The Effect on Improvement of Muscle Strength Imbalance According to Load Deviation Protocol of Whole Body Vibration Exercise (부하 편차 방식의 전신진동운동이 하지 근력 불균형 개선에 미치는 효과)

  • Seo, Shin Bae;Kang, Seung Rok;Yu, Chang Ho;Min, Jin Young;Kwon, Tae Kyu
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.30 no.10
    • /
    • pp.1095-1101
    • /
    • 2013
  • The purpose of this study was to verify the effect on improvement of muscle strength unbalance according to load deviation protocol during whole body vibration exercise. Seventeen female volunteers (age $22{\pm}3$ years, height $160{\pm}4.9$ cm, weight $49{\pm}.8$ kg) participated in this experiment. The subjects performed squat exercise in WBV platform. Exercise were performed five set a day including 15 time a set, three days a week, and during 4 weeks. Vibration stimulus was 25Hz as frequency and intensity was dominant leg 1mm and non-dominant leg 4mm. The results in WBV group showed that the differences of peak torque in 16% were getting decreasing significantly after 4 weeks from 16.2% to 5.2%. This result means that WBV with load deviation protocol could provide muscle strength exercise for muscle strength balance. Our study found out that WBV of load deviation protocol could provide muscle strength exercise for improving muscle imbalance.