• Title/Summary/Keyword: time domain data

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Capacitive compensation and consequent bandwidth expansion of 2.5 Gbps optical transmitter module (2.5Gbps 광송신 모듈의 용량선 보상 및 대역폭 확대)

  • 김성일;김상배;이해영
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.7
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    • pp.216-222
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    • 1996
  • Since many typical 2.5 Gbps optical transmitter modules use a 50$\Omega$ characteristic impedance, they require relatively high voltage and high power sources compared to the 25$\Omega$ module. However, simple replacement of the 50$\Omega$ internal matching impedance with 25$\Omega$ results in bandwidth reduction and consequent problem of data transmitter module is proposed in order to expand the modulator bandwidth. From the calculated resutls based on accurate 3-dimensional inductance analysis, we have found that the series parasitic inductance is a dominant element limiting the bandwidth and the insertion of a 2.5pF capacitor in parallel to the 20$\Omega$ matching resiter can increase the 3 dB bandwidth about 1.4GHz wider. The time-domain results show the rise time (140 psec) without the compensation is greatly improved to 63 psec with the compensation. This capacitive ocmpensation can be implemented easily and be compatible with common manufacturing process of the optical transmitter module.

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Issues in Localising 3D Sound in Space Using Head- Related Transfer Functions (머리전달함수를 이용한 공간 음상 정위의 문제점 고찰)

  • Cheung Wan-Sup;Hwang Shin;Lee Jeung-Hoon;Kyun Hyu-Sang
    • Proceedings of the Acoustical Society of Korea Conference
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    • spring
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    • pp.149-152
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    • 1999
  • This paper addresses major issues in localising sound sources in space using the experimental data set of head-related responses in the time or frequency domain. They come from the technical realisation steps for implementing the convolution of HRIR's with sound sources, the cross-talk cancellation for transaural filtering, the matched time delay compensation, etc. in real, those technical matters seem to be minor because they can be realised in off-line signal processing schemes. This paper puts much emphasis on what we misunderstood about the sets of HRTF's or HRIR's, More specifcaily, the sets of HRTF's or HRIR's of course supply relevant information to sound localisation but include much useless 'rubbish' that have made for us to fail to put spatial image into real souno signals such as voices and music's. This paper proposes possible reasons for such failure and, furthermore, introduces detained subjects that should be challenged so as to resolve them.

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Long-Term Forecasting by Wavelet-Based Filter Bank Selections and Its Application

  • Lee, Jeong-Ran;Lee, You-Lim;Oh, Hee-Seok
    • The Korean Journal of Applied Statistics
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    • v.23 no.2
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    • pp.249-261
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    • 2010
  • Long-term forecasting of seasonal time series is critical in many applications such as planning business strategies and resolving possible problems of a business company. Unlike the traditional approach that depends solely on dynamic models, Li and Hinich (2002) introduced a combination of stochastic dynamic modeling with filter bank approach for forecasting seasonal patterns using highly coherent(High-C) waveforms. We modify the filter selection and forecasting procedure on wavelet domain to be more feasible and compare the resulting predictor with one that obtained from the wavelet variance estimation method. An improvement over other seasonal pattern extraction and forecasting methods based on such as wavelet scalogram, Holt-Winters, and seasonal autoregressive integrated moving average(SARIMA) is shown in terms of the prediction error. The performance of the proposed method is illustrated by a simulation study and an application to the real stock price data.

STABILITY LIMIT PROPERTIES OF CONTROL SYSTEMS ON THE SPACE OF ADJUSTING PARAMETERS (조정파라미터 공간에서의 제어계 안정한계 특성)

  • 최순만
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2000.11a
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    • pp.135-142
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    • 2000
  • The adjusting parameter set which enable control systems to locate on stability limit can be derived from theoretical or trial methods for an existing real system. The data from the results are much available to keep a system in the Proper stability condition even to site engineers who are inexperienced in the control system. In this paper, a general one loop control system was adopted for a model system the process of which was assumed to consist of a time-delay element and a first order-lag element in series. After obtaining the corresponding parameter set for the model system by mathematical procedures, their loci on the parameter space was taken according to frequency change. The parameter set loci of stability limit showed unique pattern, and particularity , the curves on the Kg-Ti parameter space were able to be generalized in the form of, an unique exponential formula. These properties were also compared with the results taken from experimental procedures by Nyquist response method and Ziegler & Nichols method on the time domain, and both results were confirmed to be nearly same.

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Developing Customer-Oriente Service Model in the Electronic Commerce: Focus on the Customer Value, Service Quality, ad Performance (전자상거래의 고객지향적 비즈니스 모델 구축에 관한 연구 - 고객가치와 서비스 품질, 기업의 성과를 중심으로)

  • Lee, Hyun-Kyu
    • The Journal of Information Systems
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    • v.14 no.1
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    • pp.125-147
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    • 2005
  • This research focused on the comparison of corporate business mokels to explain different financial performances on the eBusiness domain. Especially, because customers have the more buying [ower tha other business areas, customer value and the service quality were prepared for independent variables and operational margin which can be obtained by publicize report was used for a dependent variable in stead of the other variables dependent on human perception as well. As a result, this research found that the customer value measured by service quality concept impact on the financial performance of eBusiness corporation positively. To find out more delicate results, structural equation was used for statistical method using 324 survey samples on 10 corporations. Though data using for statistical analysis were divided into individual and corporate level and have the time gap between research time and financial performance publicized period, the value of this research is that the customer value and service quality concepts with very objective financial information were input for constructing a research model.

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A Practical Power System Stabilizer Tuning Method and its Verification in Field Test

  • Shin, Jeong-Hoon;Nam, Su-Chul;Lee, Jae-Gul;Baek, Seung-Mook;Choy, Young-Do;Kim, Tae-Kyun
    • Journal of Electrical Engineering and Technology
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    • v.5 no.3
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    • pp.400-406
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    • 2010
  • This paper deals with parameter tuning of the Power System Stabilizer (PSS) for 612 MVA thermal power plants in the KEPCO system and its validation in a field test. In this paper, the selection of parameters, such as lead-lag time constants for phase compensation and system gain, is optimized using linear and eigenvalue analyses. This is then verified through the time-domain transient stability analysis. In the next step, the performance of PSS is finally verified by the generator's on-line field test. After the field test, measured and simulated data are also compared to prove the effectiveness of the models used in the simulations.

A Preliminary Study on Piezo-aeroelastic Energy Harvesting Using a Nonlinear Trailing-Edge Flap

  • Bae, Jae-Sung;Inman, Daniel J.
    • International Journal of Aeronautical and Space Sciences
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    • v.16 no.3
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    • pp.407-417
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    • 2015
  • Recently, piezo-aeroelastic energy harvesting has received greater attention. In the present study, a piezo-aeroelastic energy harvester using a nonlinear trailing-edge flap is proposed, and its nonlinear aeroelastic behaviors are investigated. The energy harvester is modeled using a piezo-aeroelastic model of a two-dimensional typical section airfoil with a trailing-edge flap (TEF). A piezo-aeroelastic analysis is carried out using RL and time-integration methods, and the results are verified with the experimental data. The linearizing method using a describing function is used for the frequency domain analysis of the nonlinear piezo-aeroelastic system. From the linear and nonlinear piezo-aeroelastic analysis, the limit cycle oscillation (LCO) characteristics of the proposed energy harvester with the nonlinear TEF are investigated in both the frequency and time domains. Finally, the authors discuss the air speed range for effective piezo-aeroelastic energy harvesting.

Numerical Analysis of Underwater Propeller Noise(Part 1. Non-Cavitating Noise) (수중 프로펠러의 소음 예측에 관한 연구(Part 1. 비공동 소음))

  • 설한신;이수갑;표상우;서정천
    • Journal of the Society of Naval Architects of Korea
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    • v.41 no.2
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    • pp.21-32
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    • 2004
  • The non-cavitating noise of underwater propeller is considered numerically in this study. The main purpose is to analyze non-cavitating noise from underwater propellers in various operating conditions with different configurations. Noise is predicted by using time-domain acoustic analogy, boundary element method, and computational hydro-acoustics. The flow field is analyzed with potential-based panel method, and then time-dependant pressure data are used as the input for Focus Williams-Hawkings formulation to predict far field acoustics. Furthermore, boundary element method and computational hydro-acoustics are also considered to investigate duct propeller and ducted multi-stage propeller to consider the reflection and diffraction of sound waves. With this methodology, noise intensity and directivity of each noise sources could be well analyzed.

A Comparative Study on Fault Detection Algorithm of AC Generator (교류 발전기의 고장 검출 알고리즘에 관한 비교 연구)

  • Park, Chul-Won;Shin, Kwang-Chul;Shin, Myong-Chul
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.2
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    • pp.102-108
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    • 2008
  • AC generator plays an important role of power system. The large AC generator fault may lead to large impacts or perturbations in power system. And then the protection of a generator has very important role in maintaining stability in a power system. In present, the DFT(discrete Fourier transform) based RDR(ratio differential relay) had been widely applied to a internal fault of a generator stator winding. But DFT has a serious drawback. In the course of transforming a target signal to frequency domain, time information is lost. DWT uses a time-scale region. This paper proposes an advanced fault detection algorithm using DWT(discrete Wavelet transform) to enhance the drawback of conventional DFT based relaying. To evaluate the performance of the proposed relaying, we used the test data which were sampled with 720 [Hz] per cycle and obtained from ATP(alternative transient program) simulation. And we made a comparative study of conventional DFT based RDR and the proposed relaying.

Numerical Investigations of the Experimental Techniques for Measuring the Acoustical Source Parameters of a Simplified Exhaust System (엔진 흡배기 소음원 특성의 특정법에 대한 수치적 연구)

  • 이정권;장승호
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.866-870
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    • 2001
  • Measurement techniques for in-duct acoustic source parameters can be classified into the direct method and the load method, according to whether it utilizes an extra external source or not. It is reported that the load methods yield the negative source resistance and the purpose of this paper is to clarify that the time-varying nature of the source is the main cause of this physically implausible result. For this purpose, the direct and load methods for measuring the source characteristics of a simplified fluid machine are simulated using the time domain numerical analysis. In the numerical simulations, the method of characteristics is employed and the source characteristics are calculated from the resultant data. It is shown that the load method results in negative source resistance for some frequencies, whereas the direct method yields positive values for all frequencies considered. It is found that the result of load method is quite sensitive to the change of cylinder pressure or valve profile in contrast to the direct method.

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