• Title, Summary, Keyword: Excitation source

Search Result 299, Processing Time 0.034 seconds

An Enhanced Excitation Source in LPC Vocoder (LPC Vocoder 의 Excitation Source 개선에 관한 연구)

  • Jeon, Ji-Ha;Lee, Keun-Young
    • Proceedings of the KIEE Conference
    • /
    • /
    • pp.881-883
    • /
    • 1987
  • This paper decribes a new technique for the generation of excitation sources in LPC system. We synthesize a speech signal using several excitation sources, according to residual signal energy and ZCR(zero Crossing Rate). One of the excitation sources mix the double differentiated glottal wave form source and noise source. As a result, we got improved speech signal than that produced by conventional LPC system.

  • PDF

Improved Excitation Modeling for Low-Rate CELP Speech Coding

  • Kwon, Chul-Hong
    • The Journal of the Acoustical Society of Korea
    • /
    • v.18 no.2E
    • /
    • pp.24-30
    • /
    • 1999
  • In this paper, we propose a weighting dependent mixed source model (WD-MSM) coder that is an improved version of a CELP-based mixed source model (C-MSM) coder. The coder classifies speech segments into three types : voiced, unvoiced and mixed. The excitation for a voiced frame is an adaptive source, and the excitation for an unvoiced frame is a stochastic source. The coder has a modified mixed source for a mixed frame. We apply different weighting functions for three classes. Simulation results show that the proposed coder at 4 kbits/s yields very good performance both subjectively and objectively.

  • PDF

Development of Excitation Light Source for Photodynamic Diagnosis of Cancer (광역학적 암진단을 위한 여기 광원장치의 개발)

  • Lim, Hyun-Soo
    • Journal of the Institute of Electronics Engineers of Korea SC
    • /
    • v.44 no.6
    • /
    • pp.49-56
    • /
    • 2007
  • In this paper, the development of excitation light source is proposed for excitation light of the photodynamic therapy of cancer. Since the selection of the wavelength band of excitation light has an interrelation with fluorescence generation according to the selection of a photosensitizer. This study aims at designing and evaluating light source that can stably generate light with various kinds of wavelengths in order to make possible photodynamic diagnosis using a photosensitizer and diagnosis using auto-fluorescence. The light source device was a Xenon lamp and filter wheel, composed of an optical output control through iris and filters with several wavelength bands. It also makes the inducement of auto-fluorescence possible because it is designed to generate a wavelength band of 380-420nm, 430-480nm, 480-560nm. The transmission part of the light source was developed to enhance the efficiency of light transmission. To evaluate this light source device by KFDA#s technical reference, the characteristics of the light output and wavelength band were found.

Voice Source Modeling Using Harmonic Compensated LF Model (LF 모델에 고조파 성분을 보상한 음원 모델링)

  • 이건웅;김태우홍재근
    • Proceedings of the IEEK Conference
    • /
    • /
    • pp.1247-1250
    • /
    • 1998
  • In speech synthesis, LF model is widely used for excitation signal for voice source coding system. But LF model does not represent the harmonic frequencies of excitation signal. We propose an effective method which use sinusoidal functions for representing the harmonics of voice source signal. The proposed method could achieve more exact voice source waveform and better synthesized speech quality than LF model.

  • PDF

Fabrication of a Planar UV Lighting Device Utilizing Cs3Sb Photocathode Emitters

  • Jeong, Hyo-Soo
    • Journal of the Korean Physical Society
    • /
    • v.71 no.12
    • /
    • pp.993-996
    • /
    • 2017
  • Planar ultraviolet (UV) light sources with uniform intensity are ideal for UV treatments. A newly conceived planar UV lighting device utilizing $Cs_3Sb$ mono-alkali antimonide photocathodes as flat electron emitters is presented and analyzed here. The design concept involves a panel device that utilizes photocathodes operated in a reflection mode with an external excitation light source. The excitation light source is in the blue visible light range. Commercially available UV phosphors are used as a light source of desirable UV wavelengths. The light emission characteristics of the device are investigated by measuring the optical parameters as function of applied anode voltage. The UV light emission shows that cold UV light with the spectral characteristics of near-monochromatic distribution are most effective. It also demonstrates that the UV intensity is sufficient for the UV treatment. More importantly, the planar UV lighting device is mercury free. These make them suitable for all UV applications.

Study on the Capacitor-self-excited Three-phase Synchronous Generator (A 캐패시터 자력식 삼상동기발전기에 관한 연구)

  • 정연택;김영동
    • The Transactions of the Korean Institute of Electrical Engineers
    • /
    • v.33 no.11
    • /
    • pp.425-432
    • /
    • 1984
  • This paper is to propse a new self-excitation method of synchronous generator. Instead of conventional exciter of synchronous generator, the additional winding which is arranged in addition to the armature winding, is used in this generator. The output terminal of the additional winding is connected to a capacitor and to a full wave rectifier in series. In this configuration, one source double excitation which is composed of capacitor-self-excitation by lead urrent and direct current excitation by rectifier, is induced. The result is that` The excetation efficency is improved greatly and output waveform is improved also. In three-phase synchronous generator using the new method of the one source double excitation, voltage element (shunt characteristics) and current element (series characteristics)are compounded in scalar by adapting star-point-open-rectifier system. The result is as following` The effect of load power factor angle on voltage regulation is reduced greatly, compound characteristics is become manifold by controlling capacity of capacitor, and transient response is improved.

  • PDF

The Study on Interrelationship Analysis of Domestic Road Using PSD (PSD선도를 이용한 국내노면의 상관성 분석에 관한 연구)

  • Kim, Chan-Jung;Kwon, Seong-Jin;Lee, Bong-Hyun;Kim, Hyun-Chul;Bae, Chul-Yong
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.16 no.8
    • /
    • pp.806-813
    • /
    • 2006
  • An important factor of vibration test using MAST(multi axial simulation table) system is the reliance of input excitation source. Generally the generation of input excitation source is obtained by the measured data on special road in proving ground. The measured data on special road have more exciting energy than the data of real fields, therefore the time and expense for test can be reduced. But the magnitude of input excitation source must be defined by comparison with the excited energy on real field. The object of this paper makes the data base of domestic roads for the definition of input excitation source which is obtained by the measured data on special road in proving ground. These real field data on domestic roads are analyzed by the power spectral density and interrelationship index.

Hybrid Excitation Control of SRM Drive for Reduction of Vibration and Acoustic Noise

  • Lee, Dong-Hee;Lee, Sang-Hun;Ahn, Jin-Woo;Park, Sung-Jun
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
    • /
    • v.11B no.4
    • /
    • pp.151-155
    • /
    • 2001
  • The simple motor construction and low cost, fault tolerant power electronic drive has made the switched reluctance drive a strong contender for many applications. But the switched reluctance drive does exhibit higher levels of vibration and acoustic noise than that of most competing drives. The main source of vibration in the switched reluctance drive is generated by rapid change of radial magnetic force when phase current is extinguished during commutation action. In this paper, a hybrid excitation method is proposed to reduce vibration and acoustic noise of the switched reluctance drive. The hybrid excitation has 2-phase excitation by long dwell angle as well as conventional 1-phase excitation. The vibration and acoustic noise are reduced because the scheme reduces abrupt change of excitation level by distributed and balanced excitation.

  • PDF

Development of the Fluorescence Endoscope System with Dual Light Source Apparatus (복합 광원을 갖는 형광 내시경 개발)

  • Bae, Soo-Jin;Kang, Uk
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.56 no.1
    • /
    • pp.222-226
    • /
    • 2007
  • We suggest the fluorescence endoscope system that has light source apparatus providing selectable white or excitation light. White light source generates normal color images and is easily switched over to excitation light with the wide spectrum range from 380 nm to 580 nm. 5-ALA is deposited selectively in the abnormal tissue like cancer and causes fluorescence in the red spectrum range when excited by blue spectrum range. In addition, the others of excitation light make the color background image by reflected light to allow accurate orientation and visualization of the abnormal tissue and around. According to clinical studies, the fluorescence intensity contrast that defines the fluorescence intensity of lesion over the fluorescence intensity of around has more than 2 in tumour. Proposed system is useful and objective way in early diagnosis. Furthermore, it can be used in the biopsy for tumour classification at the highest fluorescence intensity point.

A Theoretical Study of Photothermal Pulsed Radiometry Method for the Thermal Diffusivity Measurement (재료의 열확산계수 결정을 위한 광열복사법의 이론적 연구)

  • Yook, Hyung-Kyu;Yoo, Jai-Suk;Kim, Hyun-Jung;Lee, Kwang-Jai
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.29 no.1
    • /
    • pp.27-34
    • /
    • 2005
  • We analyze in detail axially symmetric theoretical study for the photothermal pulsed radiometry of a cylindrical model. The theoretical solutions describe the transient infrared radiation from the sample heated by short-duration pulsed heating. In the conventional transmission radiometry technique, the excitation source and the detector are on opposite sides of the sample, otherwise in the new single ended radiometry technique, the excitation source and the detector are on same sides of the sample. The analytical solution described for photothermal radiometry in this study would not need to cut or polish samples to measure the thermal diffusivity. Therefore the radial area and axial thickness of samples are not limited. The effects of excitation pulse duration and the area of heat source are discussed.