• Title/Summary/Keyword: light spectrum

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A Study on Recognition of the Event-Related Potential in EEG Signals Using Wavelet and Neural Network (웨이브렛과 신경회로망을 이용한 뇌 유발 전위의 인식에 관한 연구)

  • 최완규;나승유;이희영
    • Proceedings of the IEEK Conference
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    • 2000.06e
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    • pp.127-130
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    • 2000
  • Classification of Electroencephalogram(EEG) makes one of key roles in the field of clinical diagnosis, such as detection for epilepsy. Spectrum analysis using the fourier transform(FT) uses the same window to signals, so classification rate decreases for nonstationary signals such as EEG's. In this paper, wavelet power spectrum method using wavelet transform which is excellent in detection of transient components of time-varying signals is applied to the classification of three types of Event Related Potential(EP) and compared with the result by fourier transform. In the experiments, two types of photic stimulation, which are caused by eye opening/closing and artificial light, are used to collect the data to be classified. After choosing a specific range of scales, scale-averaged wavelet spectrums extracted from the wavelet power spectrum is used to find features by Back-Propagation(13P) algorithm. As a result, wavelet analysis shows superiority to fourier transform for nonstationary EEG signal classification.

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Electrical Characteristics of c-Si PV Module for the Spread of Natural Light Spectrum (자연광 스펙트럼 분포에 의한 단결정 PV 모듈의 전기적 특성)

  • Hong, Jong-Kyuong;Kang, Gi-Hwan;Park, Chi-Hong;Jung, Tae-Hee;Ryu, Se-Hwan;L, Waithiru;Ahn, Hyung-Keun;Han, Deuk-Young
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.3
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    • pp.193-198
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    • 2009
  • Recently, characteristic research by the changes in the spectrum, one of the factors that influence analysis of maximum output power of PV module, has been studied. In this paper, a one-day intensity of solar irradiation, change of spectrums with time and electrical output for spectrums are analyzed. As a result, blue-rich wavelength compared with red-rich wavelength has large variation of solar irradiance with time, so we recognized that change of solar irradiance is dominated by variation of blue~rich wavelength. Also in same intensity of solar irradiance, electrical output in blue-rich wavelength was 3-8 % higher than one in red-rich wavelength.

The Study of the Dyeability of Forsythia Koreana NAKAI (개나리 꽃잎을 이용한 염색성에 관한 연구)

  • 배상경
    • Textile Coloration and Finishing
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    • v.15 no.5
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    • pp.310-315
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    • 2003
  • The dyeing of cotton fabric with Forsythia koreana NAKAI was investigated. The colorant was extracted with methanol under various concentrations of dyestuffs at $40^\circ{C}$ and $76^\circ{C}$. UV-VIS spectrum was obtained to find the maximum wavelength of colorant. Cotton fabrics were dyed at different temperatures, mordants, in pre and post mordanting methods. The maximum wavelength of spectrum were 390nm, 410nm, 440nm. The highest K/S value was showed at 100% dye concentration, extracted at $76^\circ{C}$ and dyed at $80^\circ{C}$. The mordant effect was not good in the K/S values. The light fastness was increased at Fe-pre mordant and Cr, Fe-post mordant.

2.5 Gb/s transmission of a spectrum-sliced incoherent hight source with 0.92 nm bandwidth over 80 km of dispersion-shifted fiber

  • Shin, Sang-Yung;Han, Jung-Hee;Lee, Jae-Seung
    • Journal of the Optical Society of Korea
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    • v.2 no.1
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    • pp.22-25
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    • 1998
  • We present a spectrum broadening technique to improve the signal-to-noise ratio of spectrum sliced incoherent light sources using the fiber four-wave mixing effect which occurs in a nonlinear loop mirror located at the receiver. The initial transmission channel bandwidth of 0.92 nm was increased to 1.62 nm in the nonlinear loop mirror at the optical receiver, which enhances the signal-to-noise ratio to a desired value. Using this technique, we have demonstrated the transmission of a 2.5 Gb/s NRZ signal with the 0.92 nm bandwidth through a 80 km dispersion-shifted fiber. The measured transmission penalty was less than 0.2 dB at $1{\imes}10^{-10}$ BER.

Alignment of a ring laser cavity by using the cavity transmission spectrum control method (투과광 스펙트럼 측정법을 이용한 링레이저 공진기의 광학적 정렬)

  • 전형욱;최용진;이기홍;신상훈;이혁수;손정영
    • Korean Journal of Optics and Photonics
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    • v.8 no.6
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    • pp.456-460
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    • 1997
  • Several methods of aligning ring type cavities have been investigated for long time. The measurement of cavity transmission spectrum control is somewhat effective due to aligning cavity with measuring cavity loss at the same time. In this research, four mirrors are aligned and attached by the measurement of pulse width of the transmitted light. The intracavity loss is optimized to about 0.98%, giving the calculated total reflection coefficient of about 99.02%.

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THE NIGHT SKY SPECTRUM OF MOUNT BOHYUN

  • SHEEN YUN-KYEONG;BYUN YONG-IK
    • Journal of The Korean Astronomical Society
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    • v.37 no.2
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    • pp.87-90
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    • 2004
  • Spectrophotometry of the night sky over Mount Bohyun is presented for the nearly entire visible wavelengths of $3600{\~}$8600{\AA}$. The data was obtained under moonless clear sky in February 2004 with the 1.8-m telescope and the long slit spectrograph. The sky spectrum shows a number of strong emission lines originated from light pollution, especially due to high pressure sodium lamps. When compared to the night sky of Kitt Peak, our sky continuum is 1 to 2 magnitude brighter at all wavelengths, the worst being around the broad emission region near 6000${\AA}$. The night sky spectrum presented here with almost complete line identifications is a useful reference for arc-independent wavelength calibrations to check the gravity flexure of the spectrograph and the wavelength shift between FeNeArHe arc frames and science frames.

Detection of Atrial Tachycardia and Atrial Fibrillation Using Spectrum Analysis of Intracardiac Signal (Intracardiac Signal의 스펙트럼 분석을 통한 Atrial Tachycardia 및 Atrial Fibrillation 검출)

  • Lee, Chung-Keun;Joung, Bo-Young;Lee, Myoung-Ho;Shin, Hang-Sik
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.55 no.3
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    • pp.142-145
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    • 2006
  • Detection methods for atrial tachycardia and atrial fibrillation on the time axis have the advantages of light operational load and are easy to apply to various applications. Despite these advantages, arrhythmia detection algorithm on the time axis cannot stand much noise such as motion artifacts, moreover the peak detection algorithm has high complexity. In this paper, we use a spectrum analysis method for the detection of atrial tachycardia and atrial fibrillation. By applying spectrum analysis and digital filtering on obtained electrogram signals, we can diagnose heart arrhythmia without using peak detection algorithm.

Autism Spectrum Disorder and Eating Problems: The Imbalance of Gut Microbiota and the Gut-Brain Axis Hypothesis

  • Jiyoung Kim
    • Journal of the Korean Academy of Child and Adolescent Psychiatry
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    • v.35 no.1
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    • pp.51-56
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    • 2024
  • This review explores the complexities of autism spectrum disorder (ASD), primarily focusing on the significant eating challenges faced by children and adolescents with this neurodevelopmental condition. It is common for individuals with ASD to exhibit heightened sensitivity to various sensory aspects of food such as taste, texture, smell, and visual appeal, leading to restricted and less diverse diets. These dietary limitations are believed to contribute to an imbalance in the gut microbiota. This review elaborates on how these eating problems, coupled with the distinctive characteristics of ASD, might be influenced by and, in turn, influence the gut-brain axis, a bidirectional communication system between the gastrointestinal tract and the brain. This discussion aims to shed light on the multifaceted interactions and potential implications of diet, gut health, and neurological development and function in children and adolescents with ASD.

Evaluating Solar Light Collectors for Use in Closed Plant Production Systems (폐쇄형 식물생산 시스템에서 태양광 채광시스템 연구)

  • Lee, Sanggyu;Lee, Jaesu;Lee, Hyundong;Baek, Jeonghyun;Rho, Siyoung;Hong, Youngsin;Park, Jongwon
    • Journal of Environmental Science International
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    • v.28 no.5
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    • pp.521-526
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    • 2019
  • In this study, a solar light collector that collects and transmits solar light required for crop production in a closed plant production system was developed. The solar light collector consisted of a Fresnel lens for collecting solar light, and a tracking actuator for tracking solar light from sunrise to sunset to increase the light collection efficiency. The optical fiber that transmitted solar light was made of Glass Optical Fiber (GOF), and it had an excellent optical transmission rate. After collecting the solar light, the amount of light was measured at 5, 10, 15, 20, 25, and 30 cm distances from the GOF through the darkroom by using a light sensor logger connected to a quantum and pyranometer sensor. Compared with solar light, the light intensity of pyranometer sensor measured at 5 cm was 114% higher than solar light, and 61% at 10 cm. In addition, it was observed that it is possible to transmit the necessary amount of light for growing crops up to about 15 cm (as over 22%) through GOF. Therefore, adding diffusers to the solar light collector should be expected to replace artificial light in plant factories or plug seedlings nurseries for leafy vegetables. More studies on the solar light collection devices and the light transmission devices that have high light collection efficiency should be conducted.

Effect of Tracer Composition on Spectrum and Intensity of Burning Flame (예광제 조성이 연소 불꽃의 스펙트럼 및 광도에 미치는 영향)

  • Kwon, Soon-Kil;Hwang, Jun-Sik;Lee, Sang-Mu
    • Journal of the Korea Institute of Military Science and Technology
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    • v.9 no.4
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    • pp.90-96
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    • 2006
  • Computer simulation was carried out to develop the tracer composition of a high performance to be able to be observed by not only the naked eye but also the thermal imaging system attached to the weapon system. The results of computer simulation show that the optimum Mg content among the trace compositions is about 40% and the formulation consisted of Viton A has a higher flame temperature compared with that of chloride compound. But the only use of Viton A radiates a yellow light and the composition adding a chloride compound radiates the red light. The light intensity of the tracer composition involving Viton A is higher than that of chloride compound. The tracer composition involving Viton A shows more clear images in case of all tests.