• Title, Summary, Keyword: 이동도스펙트럼

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Theoretical Calculation on Alpha Track Density by Using an Electrostatic Ion Spectrometer (정전기분광분석방법에 의한 알파입자비적밀도의 이론적 계산연구)

  • Yoon, Suk-Chul;Ha, Chung-Woo
    • Journal of Radiation Protection and Research
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    • v.18 no.1
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    • pp.25-35
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    • 1993
  • To develop a technique of theoretical alpha track density calculation for comparison with measured track density, an electrostatic ion spectrometer was specially designed and fabricated. The mobility spectrum of first radon daughter(Po-218) in the range of $0.07{\sim}5.0cm^2/V\;s$ from the radon chamber was measured using-the electrostatic ion spectrometer. Measurement was taken in a radon chamber operated using dry particle free air passed through silica gel, activated charcoal and molecular sieve filters. The mobility of a new-born Po-218 ion measured by the electrostatic ion spectrometer was determined to be $1.92cm^2/V\;s$. A comparison of the theoretical and measured alpha track densities was completed and uncertainties concerning the shape of the spectrum were analyzed. It was found that the discrepancies in track densities are primarily Que to the neglect of wall loss of ions in the theoretical track density calculation.

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Simulation for the center-wavelength shift of interference filters by temperature variation (온도변화에 따른 간섭필터의 중심파장 이동의 전산모의)

  • 김성화;황보창권
    • Proceedings of the Optical Society of Korea Conference
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    • pp.80-81
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    • 2003
  • DWDM 필터와 같은 간섭필터는 밴드폭이 좁아지고 투과파장에 해당하는 채널의 수가 증가함에 따라 투과파장의 외부환경에 대한 안정성이 중요하다. 기존의 전자빔 증착법으로 증착된 유전체 다층박막은 일반적으로 미세기둥구조로 인해 낮은 조밀도를 가지기 때문에 외부의 습도나 온도 변화 등에 민감하다. 낮은 조밀도의 유전체 다층박막을 대기 중에 노출되었을 때, 대기 중의 습기가 기둥과 기둥 사이로 침투되어 유효굴절률의 증가로 인하여 박막의 광학두께가 증가하게 되고 결국 스펙트럼이 장파장으로 이동하게 된다. (중략)

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Analysis of Doppler Spectra in an Airborne Radar (항공기용 레이다에서의 도플러 스펙트럼 분석)

  • Lee, Jong-Gil
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.628-631
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    • 2008
  • For the remote sensing purpose, radar systems extract the target information, such as the magnitude of reflectivity and the velocity from the spectrum analysis of return echoes through the Doppler filter bank. This conventional spectrum estimation method, FFT(Fast fourier Transform) is widely used in most radar systems. However, the frequency resolution of return echoes can be seriously degraded in fast moving targets because of the short acquisition time. Since the high Doppler frequency resolution is important in the detection and tracking of fast moving targets, it can cause very unsatisfactory results. Therefore, in this paper, the parameter spectrum estimation method called AR(Autoregressive) spectrum estimation, is investigated to overcome these problems.

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PC를 이용한 신호처리 및 해석 - 대학원 교육을 중심으로 -

  • 이종원
    • Journal of the KSME
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    • v.28 no.2
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    • pp.169-174
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    • 1988
  • 신호처리 및 해석에 대한 교육효과를 증대시키기 위해서는 응용사례의 발굴, 프로젝트 개발, P C를 이용한 그래픽스 교육도 이루어져야 하며, 스펙트럼 분석기술 이외에 시간영역 파라미터 모형에 의한 신호해석기법〔예를 들어 자동회귀-이동평균(ARMA)등의 시계열 모형화〕도 최근 에는 실시간 응용의 가능성이 높아지는 추세에 있으므로 PC를 이용한 신호처리 및 해석 교육에 반영하는 것이 바람직하다.

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Characteristic Analysis on Feedback Interference Channels in Rural Regions and Sides of Highways (시외 지역과 고속도로변에서 궤환 간섭 채널의 특성 분석)

  • Moon, Woo-Sik;Seo, Man-Jung;Im, Sung-Bin
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.46 no.6
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    • pp.48-55
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    • 2009
  • The feedback interference channels are those made through the multipaths that are built by moving and stationary objects around transmit and receive antennas mounted at the same point. This paper describes the method to measure the feedback interference channels in the rural regions and sides of highways and the analysis on channel characteristic parameters. Using the measured samples, we estimated scattering functions, delay power spectra, and Doppler power spectra, and we analyzed the channels using eight parameters including coherence bandwidth, coherence time, maximum excess delay, average excess delay, rms delay spread, Doppler shift, Doppler spread, and spread factor, and delay and Doppler cumulative distributions. Even though many observations are made, note that the feedback signals of high Doppler frequencies and large energy are observed in the sides of highways due to high speed vehicles while low Doppler frequencies occurred in the rural region due to rare traffic.

전면 발광 유기 발광 소자에서 두께에 따른 발광 스펙트럼 연구

  • Yang, Ji-Won;Han, Won-Geun;Lee, Won-Jae;Lee, Ho-Sik;Kim, Tae-Wan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.20-21
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    • 2009
  • 우리는 전면 발광 소자에서 두께에 따른 발광 스펙트럼을 연구하였다. 소자 구조는 Al(100nm)/TPD(40nm)/Alq3(60nm)/LiF(0.5nm)/Al(2nm)/Ag(30nm)으로 하였다. N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine(TPD)와 tris-(8-hydroxyquinoline) aluminium(Alq3)는 전공 수송층과 발광층으로 각각 사용되었다. 반투명 전극은 Li/Al/Ag로 하였다. 유기물층과 전극은 $2\times10-5$torr의 진공도에서 열 증착하였다. 유기물과 금속의 증착 속도는 $0.5\sim1.0{\AA}/s$$0.5\sim5{\AA}/s$로 하였다. 제작된 소자는 두께가 증가할 수록 장파장으로 이동하는 현상을 보였다. 이러한 현상은 마이크로 캐비티 이론으로 설명할 수 있다. 소자는 이론적인 마이크로 캐비티 수식을 이용하여 분석하기 위해 각각의 변수를 이용하여 실험과 이론을 비교하였을 때, 각각의 스펙트럼이 거의 일치하는 것을 확인할 수 있었다.

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A Comparative Study on the Methods Estimating Wave Directional Spectrum (파향스펙트럼 추정법의 비교 연구)

  • 오병철;심재설
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.2 no.3
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    • pp.119-127
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    • 1990
  • Wave directional spectrum estimation methods for irregular waves were considered in this study. Until now, the Longuet-Higgins Method (LHM) initiated by Longuet-Higgins et al. (1963) has been widely used, but resolutions of the estimation were found to be low. Kobune's Maximum Entropy Method (MEM) for the estimation of wave directional spectrum, bas-ed on the entropy Principle showed higher resolutions comparing with the LHM . If the wave directional spectrum is of Delta functions, the MEM is exact in its estimation. It was also found that for a unimodal spectrum, if the Mitsuyasu's spreading coefficient is above 5, the estimation resolutions were high. In bimodal spectrum, as the angle difference between the two peaks increased, the resolution improved. The energy seems to transfer to the smoother peak in the smoothing of peak's peakedness. LHM has a tendency to estimate bimodal spectrum as a unimodal spectrum ; thus, except for its computational speed, the resolution of LHM falls far below that of MEM.

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Uncertainty Analysis of 1 GHz Band Impulse Spectrum Amplitude (1 GHz 대역 임펄스의 스펙트럼 진폭 불확도 평가)

  • Lee, Dong-Joon;Lee, Joo-Gwang;Kwon, Jae-Yong;Kang, Tae-Weon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.12
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    • pp.1365-1372
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    • 2012
  • This paper presents a methodology to accurately evaluate the spectral components of impulse signals which are delivered from an impulse generator through the measurement system. The complicated terms for uncertainty measurement of impulse spectrum amplitude and their analysis methods and experimental results are discussed. The expanded uncertainty of the impulse spectrum measurement is 0.015, which is believed to be the best domestic measurement capability and comparable to those of world class.

Reviews in Infrared Spectroscopy and Computational Chemistry to Reveal Rhizospheric Interactions among Organic Acids, Oxyanions and Metal oxides: Fundamental Principles and Spectrum Processing (유기산, 산화음이온 및 금속 산화물 간의 근권 내 상호작용 연구를 위한 계산화학과 적외선 분광학에 관한 총설: 기본적인 원리와 스펙트럼 처리)

  • Han, Junho;Ro, Hee-Myong
    • Journal of Korean Society of Environmental Engineers
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    • v.39 no.7
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    • pp.426-439
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    • 2017
  • This review summarizes advantage and limitation in infrared spectroscopy and computational chemistry to understand rhizospheric interaction among organic acids, oxyanions and metal oxides. Since organic acids and metal oxides determine dynamics of oxyanions in the soil environment, knowledge of fundamental mechanisms is a prerequisite for understanding the interactions at soil-water interface. Attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR) is a powerful tool to measure the interfacial reactions. However, the ATR-FTIR measurements are abstruse, because the optical characteristics for measurements are variable depending on the experimental setup. In addition, spectral overlapping is a primary obstacle to the analysis of the interfacial reaction; thus, it is essential to detect and to deconvolute bands for signal interpretation. In this review, we expained the fundamental principle for spectrum processing, and four band identification methods, such as derivative spectroscopy, two-dimension correlation spectroscopy, multivariate curve resolution, and computational chemistry with example of aqueous phosphate speciation. As a result, spectrum processing and computational chemistry improved interpretation and spectral deconvolution of overlapped spectra in relatively simple systems, but it was still unsatisfactory for the problems in more complexed system like nature. Nevertheless, we believed that our challenge would contribute practically to develop adequate analytical procedure, signal processing and protocols that could help to improve interpretation and to understand the interfacial interactions of oxyanions in natural systems.

Comparison of Dynamic Responses According to Anchorage Type of Suspesion Bridges (현수교의 정착 형식에 따른 이동하중에 의한 동적 응답의 비교)

  • Suh, Jeong In;Kim, Ho Kyung
    • Journal of Korean Society of Steel Construction
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    • v.12 no.1
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    • pp.103-110
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    • 2000
  • The suspension bridge is divided by an earth anchor and a self-anchor type according to the anchorage type. This study is to evaluate the dynamic effect of moving vehicles to suspension bridges. The results were presented with the dynamic magnification factor (DMF) by the effect of vehicle speed and weight according to the anchorage type. The vehicle model has 6 degrees of freedom to idealize nonlinear multi-leaf suspensions and elastic tires of tractor-trailer. The bridge was modelled with the 3-dimensional frame element and 3-dimensional elastic catenary cable element. The condition of deck surface is considered using the actual road spectra.

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