• Title/Summary/Keyword: frequency rate

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Effect of Electric Field Frequency on the AC Electrical Treeing Phenomena in an Epoxy/Reactive Diluent/Layered Silicate Nanocomposite

  • Park, Jae-Jun
    • Transactions on Electrical and Electronic Materials
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    • v.15 no.2
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    • pp.87-90
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    • 2014
  • The effects of electric field frequency on the ac electrical treeing phenomena in an epoxy/reactive diluent/layered silicate (1.5 wt%) were carried out, in needle-plate electrode arrangement. A layered silicate was exfoliated in an epoxy base resin, by using our ac electric field apparatus. To measure the treeing propagation rate, constant alternating current (AC) of 10 kV with three different electric field frequencies (60, 500 and 1,000 Hz) was applied to the specimen, in needle-plate electrode arrangement, at $30^{\circ}C$ of insulating oil bath. As the electric field frequency increased, the treeing propagation rate increased. At 500 Hz, the treeing propagation rate of the epoxy/PG/nanosilicate system was $0.41{\times}10^{-3}$ mm/min, which was 3.4 times slower than that of the epoxy/PG system. The electrical treeing morphology was dense bush type at 60 Hz; however, as the frequency increased, the bush type was changed to branch type, having few branches, with very slow propagation rate.

Evaluation of the Ambient Temperature Effect for the Autonomic Nervous Activity of the Young Adult through the Frequency Analysis of the Heart Rate Variability (심박변이율 주파수 분석을 통한 실내온도에 따른 건강한 성인의 자율신경계 활동 평가)

  • Shin, Hangsik
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.8
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    • pp.1240-1245
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    • 2015
  • The purpose of this paper is to investigate the autonomic nervous system activity in various ambient temperatures. To evaluate autonomic function, we use the frequency domain analysis of heart rate variability such as FFT(fast fourier transformation), AR(Auto-Regressive) model and Lomb-Scargle peridogram. HRV(heart rate variability) is calculated by using ECG recorded from 3 different temperature room which temperature is controlled in 18℃(low), 25℃(mid) and 38℃(high), respectively. Totally 22 subjects were participated in the experiment. In the results, the most significant autonomic changes caused by temperature load were found in the HF(high frequency) component of FFT and AR model. And the HF power is decreased by increasing temperature. Significance level was increased by increasing the difference of temperatures.

Implementation of Platform System for IEEE 802.15.4 Low Rate WPAN

  • Park, Joo-Ho;Kang, Young-Jin;Kim, Jae-Young
    • Proceedings of the Korea Society of Information Technology Applications Conference
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    • 2005.11a
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    • pp.191-194
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    • 2005
  • In this paper the platform system for IEEE 802.15.4 Low Rate WPAN is designed and fabricated. IEEE 802.15.4 Low Rate WP AN system serves the functions and realization of home-area network. According to the IEEE 802.15.4 standard, there are two modes, One is BPSK modulation in 868/915MHz frequency band. The other is O-QPSK modulation in 2.45GHz frequency band. In this paper we implemented the platform system mounted in one PCB board in 868/915MHz frequency band of IEEE 802.15.4 Low Rate WPAN system. We measured that the platform system which consists of digital part and RF part has good performance. Also RF part is realized by design and fabrication of the RF transceiver IC. The key issue is to make the platform system which provides the function of Low Rate WPAN system to meet the requirement of IEEE 802.15.4 standards.

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Obstructive Sleep Apnea Analysis Based on Heart Rate Variability (폐쇄성 수면 무호흡 검출을 위한 심박동변이율 분석)

  • Ye, Soo-Young;Kim, Jung-Guk;Kim, Dong-Hyun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.7
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    • pp.605-608
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    • 2011
  • In this study, OSA (the obstructive sleep apnea) periods were detected in patients with OSA during sleep because of the treatment was different according to the frequency and symptoms of obstructive sleep apnea. ANS (autonomic nervous activity) was changed by obstructive sleep apnea periods so we intended to detect the periods to care the obstructive sleep apnea patients. RR intervals, SDNN (standard deviation of normal to normal) and RMSSD (root mean square standard deviation) were calculated in time domain analysis and LF (low frequency), HF (high frequency), NHF (normalized high frequency), NLF (normalized low frequency) were calculated in frequency domain analysis of HRV (heart rate variability) with obstructive sleep apnea patients. In this paper, SDNN (standard deviation of normal to normal) of time domain analysis were decreased in the obstructive sleep apnea periods. And NLF and LF/HF ratio were increased and NHF (normalized high frequency) was decreased in the frequency domain analysis. The parameters can be used to treat obstructive sleep apnea patients by detecting the obstructive sleep apnea periods such as CPAP (continuous positive airway pressure).

High Frequency Enhancement of Sound Using Wavelet Transform

  • Yoon Won-Jung;Lee Kang-Kyu;Park Kyu-Sik
    • Proceedings of the IEEK Conference
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    • summer
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    • pp.233-236
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    • 2004
  • This paper proposes new method for the enhancement of nonexistent high frequency spectral contents from low sample rate audio signal. For example, Due to the protocol constraint, the audio bandwidth of MP3 is restricted to 16Khz. Although band-restricted MP3 audio provide savings of storage space and network bandwidth, it suffers a major problem of a loss in high frequency fidelity such as localization, ambient information, and bright nature of audio. This paper provides a new mathematical analysis for the adaptive estimation of the high frequency contents based on the nature of the input low sample rate audio. Proposed method can be worked globally to any kind of audio such as speech and music that are restricted by sampling rate and bandwidth.

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Implementation of Digital Frequency Synthesizer for High Speed Frequency Hopping (DDS를 이용한 고속 주파수 Hopping용 디지털 주파수 합성기 구현)

  • Kim Young-Wan
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2006.05a
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    • pp.607-610
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    • 2006
  • The Digital Frequency Synthesizer(DFS) that generates the wideband signal with hish speed frequency hopping rate and high frequency resolution characteristics was implemented in this paper. The DFS was applied as local oscillator for direct frequency conversion IF modules of DVB-RCS, which directly generates the transmission immediate frequency signal by using DDS and wideband PLL technologies. The DDS technology provides high speed frequency hopping rate and high frequency resolution characteristics, which ate also the DVB-RCS requirement. The wideband PLL technology also provides the wideband signal generation, which is a necessity for direct frequency conversion modules. The implemented DFS provide the spurious suppression characteristic of -50 dBc, frequency resolution of 0.233 Hz and frequency hopping rate of 125 ns, respectively. Also the DFS represent the amplitude flatness of 3 dB and less in the pass-band and phase noise characteristic of -75 dBc/Hz at 1 kHz frequency offset.

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Front-End Design for Underwater Communication System with 25 kHz Carrier Frequency and 5 kHz Symbol Rate (25kHz 반송파와 5kHz 심볼율을 갖는 수중통신 수신기용 전단부 설계)

  • Kim, Seung-Geun;Yun, Chang-Ho;Park, Jin-Young;Kim, Sea-Moon;Park, Jong-Won;Lim, Young-Kon
    • Journal of Ocean Engineering and Technology
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    • v.24 no.1
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    • pp.166-171
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    • 2010
  • In this paper, the front-end of a digital receiver with a 25 kHz carrier frequency, 5 kHz symbol rate, and any excess-bandwidth is designed using two basic facts. The first is known as the uniform sampling theorem, which states that the sampled sequence might not suffer from aliasing even if its sampling rate is lower than the Nyquist sampling rate if the analog signal is a bandpass one. The other fact is that if the sampling rate is 4 times the center frequency of the sampled sequence, the front-end processing complexity can be dramatically reduced due to the half of the sampled sequence to be multiplied by zero in the demixing process. Furthermore, the designed front-end is simplified by introducing sub-filters and sub-sampling sequences. The designed front-end is composed of an A/D converter, which takes samples of a bandpass filtered signal at a 20 kHz rate; a serial-to-parallel converter, which converts a sampled bandpass sequence to 4 parallel sub-sample sequences; 4 sub-filter blocks, which act as a frequency shifter and lowpass filter for a complex sequence; 4 synchronized switches; and 2 adders. The designed front-end dramatically reduces the computational complexity by more than 50% for frequency shifting and lowpass filtering operations since a conventional front-end requires a frequency shifting and two lowpass filtering operations to get one lowpass complex sample, while the proposed front-end requires only four filtering operation to get four lowpass complex samples, which is equivalent to one filtering operation for one sample.

A Study on the pattern of tenant layout in the Urban Entertainment Center (도심 엔터테인먼트 쇼핑센터(UEC)의 테넌트 배치 형태에 관한 연구)

  • Lee, Hyunsoo;Oh, Jung-Ah
    • Korean Institute of Interior Design Journal
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    • v.21 no.6
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    • pp.233-242
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    • 2012
  • The purpose of this study is to analyze the pattern of tenant layout for selected cases of five different Urban Entertainment Center(UEC) in Seoul. This research deals with the process of gaining tenant layout pattern of 40 different types. It is composed of three combination unit with tenants of the same or different consumption mode, which is divided into four different functions of retail, entertainment, dining, and service. Then, every tenant of research cases is classified as one of the fabric type, and the data is analyzed to gain its frequency rate with SPSS 14.0 program. The following is the overall explanation of the result for this research. The frequency of tenant layout pattern between the same consumption mode shows the high rate when compared to the other patterns with different consumption mode. For example, the frequency rate of tenant layout pattern which retail and dining consumption mode are placed side by side like RRR and DDD is high. Interestingly, the frequency rate of RRR type of tenant layout pattern that sells the similar products shows especially high level. It can provide the effective environment for shoppers to compare retail goods in many different stores as producing synergic effects when they are located near each other, so this strategy should be considered when planning tenants in UEC environment. Moreover, in case of dining tenants, when they are clustered together in the UEC environment it can play a role as an anchor tenant. Tenant layout pattern of dining-retail and dining-service consumption mode shows the high frequency rate than other layout pattern with other consumption mode. Besides, entertainment consumption tenants combined with dining or retail tenants show the high frequency rate when compared to the pattern combined with service consumption mode.

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Improvement of Bit Rate applying the Speaking Rate and PSOLA Technique of Speech in CELP Vocoder (음성신호의 발성율과 PSOLA기법을 적용한 음성 보코더 전송률 개선에 관한 연구)

  • 장경아;서지호;배명진
    • Proceedings of the IEEK Conference
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    • 2003.11a
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    • pp.45-48
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    • 2003
  • In general, speech coding methods are classified into the following three categories: the waveform coding, the source coding and the hybrid coding. Fast speaking is possible to encode with a few information compared with slow speaking rate. In case of speaking rate, low frequency band is more important than high frequency band while listening. Speech vocoding technique is developing to way with low bit rate and complexity and high sound quality. the CELP type of vocoder support very good sound quality with low bit rate but these vocoders don't consider about the speaking rate. When we consider speaking rate and encode the frame depending on the speaking rate, the bit rate is able to reduce the bit rate than the conventional vocoder. We propose the technique to estimate the speaking rate and applied PSOLA technique in case of the frame of slow speaking rate. As a result of simulation bit rate can be reduced about 300 bps.

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Comparison of Psychophysical Maximum Acceptable Weight of Load for Different Frequency of Manual Materials Handling Tasks (인력물자취급시 작업빈도에 따른 인체심리학적 최대허용중량의 비교 연구)

  • 정성학;김홍기
    • Proceedings of the ESK Conference
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    • 1997.04a
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    • pp.39-49
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    • 1997
  • The objective of this study was to make comparison of the psychophysical MAWLs for different manual materials handling tasks. Lifting activities with four different lifting frequencies (2, 5, 8, 11 lifts/min) for one lifting range from floor to 76cm height were studied. The oxygen consumption rate and heart rate were measured or recorded while subjects were lifting their MAWLs. Psychophysical MAWL decreased from 22.38 kg to 7.48 kg, while th oxygen consumption rate with the MAWL increased from 717.8 ml/min to 1114.7 ml/min as the frequency increased from 2 to 11 Lifts/min. Heart rate also increased from 104.5 to 120.7 bpm. It was found that the relationship between MAWL and frequency can be described best by the exponentaial function with the R-sq value 0.9865 for this study. The percent ratio of oxygen consumption rate with the MAWL and PWC ranged from 28% to 43%.

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