• Title/Summary/Keyword: Power Spectrum Density

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Visible Light Spectrum of H2 Plasma Generated a Commercial Electric Power in the Parallel Plate Reactor (상용전원 평행판전극 방전장치에서 수소플라스마의 가시광선스펙트럼)

  • Choi, Woon Sang;Ji, Taek Sang;Kang, Sung Soo
    • Journal of Korean Ophthalmic Optics Society
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    • v.4 no.1
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    • pp.15-20
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    • 1999
  • Visible light spectrum emitted from $H_2$ plasma in the parallel plate reactor using a commercial electric power are investigated by optical emission spectroscopy. Intensity of visible light is measured as a function of $H_2$ pressure and discharging power, and the intensity is compared with plasma density measured with the probe. As a result, the intensity is affected by plasma density and the plasma density is controlled the $H_2$ pressure and the discharging power.

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Generation of Artificial Earthquake Ground Motions using Nonstationary Random Process-Modification of Power Spectrum Compatible with Design Response Spectrum- (Nonstationary Random Process를 이용한 인공지진파 발생 -설계응답스펙트럼에 의한 파워스펙트럼의 조정-)

  • 김승훈
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1999.04a
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    • pp.61-68
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    • 1999
  • In the nonlinear dynamic structural analysis the given ground excitation as an input should be well defined. Because of the lack of recorded accelerograms in Korea it is required to generate an artificial earthquake by a stochastic model of ground excitation with various dynamic properties rather than recorded accelerograms. It is well known that earthquake motions are generally non-stationary with time-varying intensity and frequency content. Many researchers have proposed non-stationary random process models. Yeh and Wen (1990) proposed a non-stationary modulation function and a power spectral density function to describe such non-stationary characteristics. Satio and Wen(1994) proposed a non-stationary stochastic process model to generate earthquake ground motions which are compatible with design reponse spectrum at sites in Japan. this paper shows the process to modify power spectrum compatible with target design response spectrum for generating of nonstationary artificial earthquake ground motions. Target reponse spectrum is chosen by ATC14 to calibrate the response spectrum according to a give recurrence period.

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POWER SPECTRUM ANALYSIS OF THE OMC1 IMAGE AT 1.1MM WAVELENGTH

  • Youn, So-Young;Kim, Sung-Eun
    • Journal of The Korean Astronomical Society
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    • v.45 no.4
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    • pp.93-99
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    • 2012
  • We present a 1.1mm emission map of the OMC1 region observed with AzTEC, a new large-format array composed of 144 silicon-nitride micromesh bolometers, that was in use at the James Clerk Maxwell Telescope (JCMT). These AzTEC observations reveal dozens of cloud cores and a tail of filaments in a manner that is almost identical to the submillimeter continuum emission of the entire OMC1 region at 450 and $850{\mu}m$. We perform Fourier analysis of the image with a modified periodogram and the density power spectrum, which provides the distribution of the length scale of the structures, is determined. The expected value of the periodogram converges to the resulting power spectrum in the mean squared sense. The present analysis reveals that the power spectrum steepens at relatively smaller scales. At larger scales, the spectrum flattens and the power law becomes shallower. The power spectra of the 1.1mm emission show clear deviations from a single power law. We find that at least three components of power law might be fitted to the calculated power spectrum of the 1.1mm emission. The slope of the best fit power law, ${\gamma}{\approx}-2.7$ is similar to those values found in numerical simulations. The effect of beam size and the noise spectrum on the shape and slope of the power spectrum are also included in the present analysis. The slope of the power law changes significantly at higher spatial frequency as the beam size increases.

The development of hydraulic suspension system capable of vehicle height at driving and the comparative analysis of vibration characteristic (주행중 차고 조절이 가능한 유압식 현가장치 개발 및 진동특성 비교 분석)

  • Kang, Hyung-Sun;Baek, Jong-Jin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.2
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    • pp.561-566
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    • 2013
  • This study aims to develop the control system of vehicle height and apply this developed system to common passenger car. The vibration characteristics to affect ride comfort are examined through driving tests. The hydraulic control system of vehicle height is designed by Macpherson type used most commonly at current passenger car. Tests in this study are operated by the vehicle installed with genuine suspension system of Macpherson type, tuning suspension system and hydraulic control system of vehicle height. As vibration characteristics transmitted to vehicle become random types values of PSD(Power Spectrum Density) are compared.

Fatigue Damage Combination for Spread Mooring System under Stationary Random Process with Bimodal Spectrum Characteristics (바이모달 스펙트럼 특성을 가지는 정상확률과정에 대한 다점계류라인의 피로손상도 조합기법 연구)

  • Lim, Yu-Chang;Kim, Kyung-Su;Choung, Joon-Mo
    • Journal of the Society of Naval Architects of Korea
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    • v.47 no.6
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    • pp.813-820
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    • 2010
  • The spread mooring system for FPSO is developed to explore deep sea area, in which swell is dominant. It is known that the tension response of mooring lines in this sea area shows bimodal spectrum. Assuming normal distribution of tension profile and Rayleigh distribution of tension amplitude, the power spectral density function (PSD) of the mooring tension under the bimodal stationary random process is applied for the calculation of spectrum fatigue. Three popular methods, which are simple summation method, combined spectrum method and Jioa-Moan method, are used to combine fatigue damages from bimodal spectrum characteristics. Each damage value is compared with damage using Rainflow Cycle Counting (RCC) method which is believed to be close to exact solution. Vanmarcke' parameter and RMS(Root Mean Square) ratio are employed to assess relative damage variations between from RCC method and from three combination methods. Finally the most reliable fatigue damage combining method for spread mooring system is suggested.

Coexistence of OFDM-Based IMT-Advanced and FM Broadcasting Systems

  • Shamsan, Zaid A.;Rahman, Tharek A.;Kamarudin, Muhammad R.;Al-Hetar, Abdulaziz M.;Jo, Han-Shin
    • ETRI Journal
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    • v.33 no.2
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    • pp.279-282
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    • 2011
  • Coexistence analysis is extremely important in examining the possibility for spectrum sharing between orthogonal frequency-division multiplexing (OFDM)-based international mobile telecommunications (IMT)-Advanced and other wireless services. In this letter, a new closed form method is derived based on power spectral density analysis in order to analyze the coexistence of OFDM-based IMT-Advanced systems and broadcasting frequency modulation (FM) systems. The proposed method evaluates more exact interference power of IMT-Advanced systems in FM broadcasting systems than the advanced minimum coupling loss (A-MCL) method. Numerical results show that the interference power is 1.3 dB and 3 dB less than that obtained using the A-MCL method at cochannel and adjacent channel, respectively. This reduces the minimum separation distance between the two systems, which eventually saves spectrum resources.

Development for the Index of an Anesthesia Depth using the Power Spectrum Density Analysis (뇌파 스펙트럼 분석에 의한 마취 심도 지표 개발)

  • Ye, Soo-Young;Baik, Swang-Wan;Kim, Jae-Hyung;Park, Jun-Mo;Jeon, Gye-Rok
    • Journal of Biomedical Engineering Research
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    • v.30 no.4
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    • pp.327-332
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    • 2009
  • In this paper, new index was developed to estimate the depth of anesthesia during general anesthesia using EEG. Analysis of the power spectral density(PSD) of EEG was used to develop new parameters because EEG signal tends to have slow wave during anesthesia. Classifier for index creator was developed by using SEF, BDR and BTR parameters, which are calculated by power spectral density. EEG data were obtained from 7 patients (ASA I, II) during general anesthesia with Sevoflurane. The anesthetic depth evaluation indexes ranged from 0 to 100. The average were $86.05{\pm}10.1$, $36.98{\pm}20.2$, $15.33{\pm}13.6$, $50.87{\pm}16.5$ and $87.72{\pm}11.7$ for the states of pre-operation, induction of anesthesia, operation, awaked and post-operation, respectively. The results show that while the depth of anesthesia was evaluated, more accurate information can be provided for anesthetician.

Factors Affecting Acoustic Responses of Egg Shell (난각의 음향반응에 영향을 주는 인자)

  • 조한근;최완규
    • Journal of Biosystems Engineering
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    • v.22 no.1
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    • pp.41-48
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    • 1997
  • A nondestructive quality inspection technique using acoustic impulse response method was studied to investigate the feasibility of egg shell inspection. An experimental system was built to generate impact force, to measure the response signal and to analyze the frequency spectrum. This system includes an impulse generating unit, an egg holding seat, a microphone with preamplifier, and a digital oscilloscope connected to Personal Computer by RS-232C interface. The factors such as impulse generating method, egg holding method, and sensor location were evaluated by analyzing the power spectrum density of the measured signal. The results obtained are summarized as follows : 1. From the sampled eggs, the proper conditions for detecting damaged eggs were found as followings; ceramic for the impact ball material, rubber for egg seat material, 20 degrees for an impact angle of pendulum, 10mm for the distance between egg and sensor, the sharp side for impacting part, and 180 degrees for the location of sensor. 2. Examination of the Fourier transformed analysis in beth normal and damaged eggs revealed that those factors such as the resonant frequency, a number of peak frequencies and the magnitude of power spectrum were important to detect damaged eggs.

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Tracked Vehicle Vibration Environmental Comparison using Fatigue Damage Spectrum (Fatigue Damage Spectrum을 이용한 궤도차량의 진동환경 비교)

  • 김재하;최병민;우호길
    • Journal of the Korea Institute of Military Science and Technology
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    • v.3 no.1
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    • pp.191-197
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    • 2000
  • This paper provides the test results of tracked vehicle at each driving condition and life cycle. Fatigue Damage Spectrum(FDS) has evaluated with the Power Spectrum Density(PSD) and the life time of equipment. Finally, provisional vibration qualification test level is evaluated.

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Evaporating Particle Behaviors and plasma Parameters by Spectroscopic Method in laser Welding (레이저 용접시 분광학적 수법에 의한 증발입자의 거동과 플라즈마 물성의 계측)

  • 김윤해
    • Journal of Advanced Marine Engineering and Technology
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    • v.23 no.4
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    • pp.514-522
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    • 1999
  • The laser-induced plasma affects greatly on the results of welding process. moreover selective evaporation loss of alloying elements leads to change in chemical composition of weld metal as well as the mechanical properties of welded joint. this study was undertaken to obtain a fundamental knowledge of pulsed laser welding phenomena especially evaporation mechanism of different aluminum alloys. The intensities of molecular spectra of AlO and MgO were different each other depeding on the power density of a laser beam Under the low power density condition the MgO band spectrum was predominant in intensity while the AlO spectra became much stronger with an increase in the power density. These behaviors have been attributed to the difference in evaporation phenomena of Al and Mg metals with different boiling points and latent heats of vaporization. The time-averaged plasma temperature and electron number density were determined by spectroscopic methods and consequently the obtained temperature was $3,280{\pm}150K$ and the electron number density was $1.85{\times}10^{19}\;l/m^3$.

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