• Title/Summary/Keyword: frequency characteristics

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A Study on the Characteristics of Observation seen in the Process of Perception and Recognition of Space (공간의 지각과 인지과정에 나타난 주시메커니즘 특성 연구)

  • Kim, Jong-Ha
    • Korean Institute of Interior Design Journal
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    • v.22 no.6
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    • pp.108-118
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    • 2013
  • This study has analyzed the process of space information perceived and recognized through the estimation of observation frequency and number according to the time range of observation data acquired from observation experiment with the object of hospital lobby. The followings are the results analyzed at this study. First, the continual observation of 3 and 6 times was attentive and conscious for probing to find an object rather than for acquiring exact information and that of 9 times could be regarded as the time for acquiring visual appreciation. However, the repetitive occurrence of high and low frequencies can be thought of repetitive acts for visual appreciation. Second, the continual observation of 3 and 6 times had the highest observation frequency of II, while that of 9 times had the highest observation frequency of III. In case of 3 and 6 times, the observation frequency had the tendency to become a little higher after being low since V, and in case of 9 times it had the repetition of becoming low and high and from IX it characteristically got higher. This feature can be thought to be the process that the subject repeats the fixation and movement of observation at a visual activity for perception and recognition. In the process of first observation, the observation frequency was the highest after 20 seconds or so, but since then, it gets lower and repeatedly gets higher and lower as time passes. After 90 seconds, the frequency showed the tendency of getting higher continuously. Third, the examination of changing features of frequency may show the characteristics of exploration for and attention to space but if the observation frequency is not associated with observation times for analysis there will a limitation that the features of observation frequency cannot be clarified. Accordingly, the simultaneous analysis of both is very effective for estimating the observation characteristics seen at the processes of perception and recognition. Fourth, the general analysis of the both revealed: with the progress of observation time the discontinuous space exploration decreased, and as the observation time got longer the fixed attention to a specific spot increased. Fifth, in order to estimate the observation characteristics by the change of time range the observation frequency and times by trend line was analyzed, which approach seems to be an appropriate technique that can comprehensively show the overall flow of time series data.

Acoustic and Stroboscopic Characteristics of Normal Person's Voices with Advancing Age (연령증가에 따른 정상 노인의 음향분석학적 특징)

  • 진성민;권기환;강현국
    • Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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    • v.8 no.1
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    • pp.44-48
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    • 1997
  • Anatomic and physiological changes of the larynx with advancing age result in morphologic changes of the vocal fold and reduced control of the phonatory mechanism in elderly individuals and are reflected in increased unstability of fundamental frequency (Fo). The purpose of this study is to increase current understanding of acoustic and stroboscopic characteristics of normal elderly persons voices. First, phonated /a/ vowel productions by 40 normal adults (20 to 40 years, 20 men and 20 women) and 40 normal elderly persons (60 to 80 years,20 men and 20 women) were analyzed, using CSL (model 4300B) acoustic analysis software, to obtain acoustic measures related to fundamental frequency stability nd vocal resonance characteristics. Second, stroboscopic images of the vocal fold behavior in all subjects were analyzed by experienced specialists. In the men, fundamental frequency variation (vFe) (p<0.01), jitter. (p<0.05), and shimmer (p<0.05) for the older group were significantly higher than the value for the adult group. In the stroboscopic findings, edema of vocal fold had a significant finding in aged men (15%). In the women, vFo (p<0.05), jitter (p<0.05), and noise to harmonic ratio (NHR) (p<0.05) for the older group were significantly higher than the value for e adult group and first formant frequency (F1) (p<0.01) and second formant frequency (F2) (p<0.01) for. the older group were significantly lower than the value for the adult group. In the stroboscopic findings, vocal fold atrophy had a significant finding in aged women (25%). Frequency stability, as reflected by vFo, jitter, shimmer, and NHR, decreases with advancing age in men and women and spectral analysis of phonated /a/ vowel productions reveals the lowering of the frequency of F1 and second F2 with advancing age, especially in aged women. Change in the mass of vocal folds, due to atrophy or edema, is considered to be the greatest factor in these acoustic changes.

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Automatic Modulation Recognition Algorithm Based on Cyclic Moment and New Modified Cumulant for Analog and Digital Modulated Signals (Cyclic Moment 및 변형 Cumulant를 기반으로 한 아날로그 및 디지털 변조신호 자동변조인식 알고리즘)

  • Kim, Dong-Ho;Kim, Jae-Yoon;Sim, Kyu-Hong;Ahn, Jun-Il
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.9
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    • pp.2009-2019
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    • 2013
  • In this paper, we propose an automatic modulation recognition algorithm based on cyclic moment and new modified cumulant for analog and digital modulation signals. It is noteworthy that each modulated signal has different cycle frequency characteristics according to its order of cyclic moment. By means of this characteristics as classification features, various modulated signals can be efficiently classified. Also, to identify modulated signals having the same cycle frequency characteristics, we take advantage of the additional classification factors such as variations of envelope and phase as well as modified cumulant. The proposed algorithm was evaluated by considering the number of symbols, SNR, and frequency offset. In the simulation condition where the number of gathered symbols was about 819, and SNR and frequency offset were above 10dB and below 25%, respectively, the average accuracy of the proposed algorithm was more than 95%.

Characterization of Acousto-ultrasonic Signals for Stamping Tool Wear (프레스 금형 마모에 대한 음-초음파 신호 특성 분석)

  • Kim, Yong-Yun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.4
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    • pp.386-392
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    • 2009
  • This paper reports on the research which investigates acoustic signals acquired in progressive compressing, hole blanking, shearing and burr compacting process. The work piece is the head pin of the electric connector, whose raw material is the preformed steel bar. An acoustic sensor was set on the bed of hydraulic press. Because the acquired signals include the dynamic characteristics generated for all the processes, it is required to investigate signal characteristics corresponding to unit process. The corresponding dynamic characteristics to the respective process were first studied by analyzing the signals respectively acquired from compressing, blanking and compacting process. The combined signals were then periodically analyzed from the grinding to the grinding in the sound frequency domain and in the ultrasonic wave. The frequency of around 9 kHz in the sound frequency domain was much correlated to the tool wear. The characteristic frequency in the acoustic emission domain between 100 kHz and 500 kHz was not only clearly observed right after tool grinding but its amplitude was also related to the wear. The frequency amplitudes of 160 kHz and 320 kHz were big enough to be classified by the noise. The noise amplitudes are getting bigger, and their energy was much bigger as coming to the next regrinding. The signal analysis was based on the real time data and its frequency spectrum by Fourier Transform. As a result, the acousto-ultrasonic signals were much related to the tool wear progression.

A Study on the Characteristics Analysis of LLC AC to DC High Frequency Resonant Converter capable of ZVZCS (ZVZCS가 가능한 LLC AC to DC 고주파 공진 컨버터의 특성 해석에 관한 연구)

  • Kim, Jong-Hae
    • Journal of IKEEE
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    • v.25 no.4
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    • pp.741-749
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    • 2021
  • This paper presents the current-fed type LLC AC to DC high frequency resonant converter capable of ZVZCS(Zero-Voltage and Zero-Current Switching). The current-fed type LLC AC to DC high frequency resonant converter proposed in this paper could operate not only in ZVS(Zero-Voltage Switching) operation by connecting the resonant capacitors(C1, C2) in parallel across the switching devices but also in ZCS(Zero-Current Switching) operation of the secondary diode. The ZVS and ZCS operations can reduce the turn-on loss of the switching devices and the turn-off loss of the secondary diodes, respectively. The circuit analysis of current-fed type LLC AC to DC high frequency resonant converter proposed in this paper is addressed generally by adopting the normalized parameters. The operating characteristics of proposed LLC AC to DC high frequency resonant converter were also evaluated by using the normalized control parameters such as the normalized control frequency(μ), the normalized load resistor(λ) and so on. Based on the characteristic values through the characteristics of evaluation, an example of the design method of proposed LLC AC to DC high frequency resonant converter is suggested, and the validity of the theoretical analysis is confirmed using the experimental results and PSIM simulation.

High-frequency Current Distribution Control (고주파 전류의 수평적 경로 유도)

  • Lim, Han-Sang;Park, Jae-Hong
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.6
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    • pp.807-814
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    • 1999
  • In this paper, it is shown that high frequency current can be controlled to concentrate near the desired path in a conducting plate. A conducting plate is modelled to examine current distribution. And current distribution is analyzed in view of the frequency and geometric characteristics of current path. The high frequency current behavior from the analysis is compared with the experiments. The results, obtained by the experiments of test specimens, are in good agreement with the analytical results.

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A Study on the Propagation Characteristics along the Microstrip Lines using Wavelet Transforms (웨이브릿 변환을 이용한 마이크로스트립 선로에서의 전파 특성 연구)

  • 이재웅;송용원;김건욱;박한규
    • Proceedings of the IEEK Conference
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    • 1999.06a
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    • pp.223-226
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    • 1999
  • We study the propagation property of the transient signals along the microstrip using the wavelet transform. Wavelet transform can offer the time-frequency windows. It makes the resolution of time high in high frequency range and the resolution of frequency high in low frequency range. So It is useful to analyze the signals which have both low and high frequency components.

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The characteristic analyses and output frequency tracking control of a high frequency inverter (고주파 인버터의 특성해석 및 출력주파수 추종제어)

  • 이종무;김영석;조기연
    • 제어로봇시스템학회:학술대회논문집
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    • 1987.10b
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    • pp.597-602
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    • 1987
  • This paper proposes a voltage-fed high frequency resonant inverter having variable voltage variable frequency(VVVF) control function. VVVF control is performed by PWM-TRC method in the boost type chopper and PFM-TRC method in the high frequency resonant inverter. This circuit is suitable for induction heating and melting power supply in industry. The operating characteristics of this inverter are discussed from a theoretical point of view. The results of operating characteristic analyses are given leading to complete designing data.

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A Study on the measurement of frequency stability using beat frequency method (비트주파수 방식을 이용한 주파수 안정도 측정에 관한 연구)

  • 김영범;정낙삼
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.12 no.4
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    • pp.365-372
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    • 1987
  • This paper describes the basic theory and construction of the frequency stability measurement system by beat frequency method, one kind of the accurate measurement technologies of frequency stability in time domain. The characteristics of the real system is also investigated.

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Design and Resonant Characteristics of the Ultrasonic Sensor for Gas Flowmeter (기체유량계용 초음파 센서의 설계 및 공진 특성)

  • Hong, Jae-Il;Lee, Sang-Cheol
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.51 no.4
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    • pp.193-197
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    • 2002
  • In this paper, the ultrasonic sensor for gas flowmeter was simulated, fabricated and measured according to the assembly step and the piezoelectric vibrator layers. The simulated resonant frequency and the measured resonant frequency were similar except two layer sensor. The simulated resonant frequency of three layer sensor was 48 kHz and the measured resonant frequency of three layer sensor was 45.2 kHz. From the results, the ultrasonic sensor for gas flowmeter could be designed and expected without fabrication.