• Title/Summary/Keyword: transfer function.

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Over-Sampling Rate for Accurate Evaluation of MLFMM Transfer Function (MLFMM의 Transfer 함수의 정확한 계산을 위한 오버샘플링 비율)

  • Lee, Hyunsoo;Rim, Jae-Won;Koh, Il-Suek
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.10
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    • pp.811-816
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    • 2018
  • When applying the MLFMM algorithm to a large scattering problem, the accuracy of the calculation of the transfer function has a crucial effect on the final simulation results. The numerical accuracy for the double integral on the unit sphere is strongly dependent on the sampling number. With an increasing the sampling points, the overall required memory and running time of the MLFMM simulation also increases. Hence, an optimal over-sampling rate for the number of the sampling points is numerically obtained, which is verified for a real large scattering problem.

Motion Error Analysis of the Porous Air Bearing Stages Using the Transfer Function (전달함수를 이용한 다공질 공기베어링 스테이지의 운동오차해석)

  • 박천홍;이후상
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.7
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    • pp.185-194
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    • 2004
  • In order to analyze the motion errors of the aerostatic stage, it is necessary to consider the influence of the moment variation occurred inside the pads. In this paper, a motion error analysis method utilizing the transfer functions on the reaction force and moment is proposed, and general characteristics of the transfer functions are discussed. Calculated motion errors by the proposed method show good agreement with the ones calculated by Multi fad Method, which is considered the entire table as an analysis object. Also, by the introduction of the transfer function of motion errors, which represent the relationship between the spatial frequency components of the rail form error and motion errors, motional characteristics of the porous aerostatic stage can be generalized. In detail, the influence of the spatial frequencies is analyzed qualitatively, and the patterns of the insensitive frequencies which almost do not affect the linear motion error or angular motion error according to the rail length ratio and the number of the pad are verified. The relationship between the moment variation occurred inside the pads and the motion errors is also verified together.

A Simple Method for Frequency Domain Identification

  • Choe, Yeon-Wook
    • 제어로봇시스템학회:학술대회논문집
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    • 1998.10a
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    • pp.129-134
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    • 1998
  • In this paper, a simple method is presented to synthesize a transfer function from experimentally obtained gain and phase data. The method we offer here is based on the previous method given by M.Hassul etc. [1], where they proposed relevant formulas in a straightforward manner so that undergraduate students could follow the development more easily. This method, however, inevitably is accompanied by a significant difference between the real and identified model especially in the low frequency region. We solve this problem by introducing a new weighting function that can be determined by using the additive uncertainty of the Identified transfer function.

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Synthesis and Analysis of Optical Transfer Function of the Modified Triangular Interferometer by Two - pupil Synthesis Method

  • Kim, Soo-Gil
    • Journal of the Optical Society of Korea
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    • v.8 no.4
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    • pp.182-187
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    • 2004
  • We synthesized and analyzed the optical transfer function(OTF) of the modified triangular interferometer (MTI) using two-pupil synthesis method. Also, we presented the optimal MTI, which can obtain any bipolar function by combining two wave plates and a linear polarizer. By using the proposed MTI, we can obtain the complex hologram without bias and conjugate image.

Critical earthquake input energy to connected building structures using impulse input

  • Fukumoto, Yoshiyuki;Takewaki, Izuru
    • Earthquakes and Structures
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    • v.9 no.6
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    • pp.1133-1152
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    • 2015
  • A frequency-domain method is developed for evaluating the earthquake input energy to two building structures connected by viscous dampers. It is shown that the earthquake input energies to respective building structures and viscous connecting dampers can be defined as works done by the boundary forces between the subsystems on their corresponding displacements. It is demonstrated that the proposed energy transfer function is very useful for clear understanding of dependence of energy consumption ratios in respective buildings and connecting viscous dampers on their properties. It can be shown that the area of the energy transfer function for the total system is constant regardless of natural period and damping ratio because the constant Fourier amplitude of the input acceleration, relating directly the area of the energy transfer function to the input energy, indicates the Dirac delta function and only an initial velocity (kinetic energy) is given in this case. Owing to the constant area property of the energy transfer functions, the total input energy to the overall system including both buildings and connecting viscous dampers is approximately constant regardless of the quantity of connecting viscous dampers. This property leads to an advantageous feature that, if the energy consumption in the connecting viscous dampers increases, the input energies to the buildings can be reduced drastically. For the worst case analysis, critical excitation problems with respect to the impulse interval for double impulse (simplification of pulse-type impulsive ground motion) and multiple impulses (simplification of long-duration ground motion) are considered and their solutions are provided.

Image quality assessment of color LCD monitors by polychromatic modulation transfer function (다색광전달함수를 사용한 컬러 LCD 모니터의 광학적 상평가법)

  • Song, Jong-Sup;Jo, Jae-Heung;Hong, Sung-Mok;Lee, Yun-Woo;Yang, Ho-Soon;Cho, Hyun-Mo;Lee, In-Won
    • Korean Journal of Optics and Photonics
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    • v.16 no.1
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    • pp.63-70
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    • 2005
  • We propose a method for evaluating the image quality of color liquid crystal display(LCD) monitors by using the polychromatic modulation transfer function(PMTF), which is calculated from the modulation transfer function(MTF) weighted by the overall color response of the system including the test LCD monitor. We confirm that experimental results using the PMTF agree well with simulated results of the PMTF of a color LCD monitor by using three bar targets with different amplitudes and three elementary colors such as red(R), green(G), and blue(B). As a results, we should choose the PMTF instead of the white color MTF or monochromatic MTF in order to evaluate correctly the image quality of color LCD monitors.

Transfer Functional Modeling Using Soil Moisture Measurements at a Steep Forest Hillslope (산지사면의 실측토양수분을 이용한 전이함수 모형의 적용)

  • Kim, Sang-Hyun
    • Journal of Environmental Science International
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    • v.22 no.4
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    • pp.415-424
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    • 2013
  • In this paper, time series of soil moisture were measured for a steep forest hillslope to model and understand distinct hydrological behaviours along two different transects. The transfer function analysis was presented to characterize temporal response patterns of soil moisture for rainfall events. The rainfall is a main driver of soil moisture variation, and its stochastic characteristic was properly treated prior to the transfer function delineation between rainfall and soil moisture measurements. Using field measurements for two transects during the rainy season in 2007 obtained from the Bumrunsa hillslope located in the Sulmachun watershed, a systematic transfer functional modeling was performed to configure the relationships between rainfall and soil moisture responses. The analysis indicated the spatial variation pattern of hillslope hydrological processes, which can be explained by the relative contribution of vertical, lateral and return flows and the impact of transect topography.

Transfer Function of Structure-borne Noise to Underwater Radiated Noise (고체음의 수중방사소음 전달함수)

  • 김재승;김현실;김상렬
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.138-142
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    • 2001
  • A comparison between theoretical and measured transfer function, which relates structure-borne noise source level to underwater radiated noise, of a naval ship is presented in this study. Transfer functions are obtained by dividing far field underwater noise by the value of structure borne noise source levels below machinery mounts. In prediction, statistical energy analysis of the whole ship structure is used to get vibration levels of wetted hull plates below water line. Then, far field radiated noise is calculated by summing up contributions from each plates using vibration levels and radiation efficiencies. And 1/3-octave band underwater sound pressure at the distance of 1 m away from the hull were measured to get experimental transfer functions. The two transfer functions are compared to show resonable agreements in spite of the subtle physical differences between each other.

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The Impact of the Mentoring Functions on the Motivation to Adopt Knowledge, the Success of Knowledge Transfer (멘토링 기능이 신입 판매원의 지식채택 동기, 지식이전 성공에 미치는 영향)

  • Lee, In Suk;Choi, Sun Gyu;Ji, Seong Goo
    • Knowledge Management Research
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    • v.11 no.3
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    • pp.13-29
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    • 2010
  • This study aims to investigate the effect of mentoring functions (career development, role modeling, and psychosocial function) on the motivation to adopt knowledge and the success of knowledge transfer in formal mentoring relations. There are considerable empirical investigation into the antecedents and consequences of mentoring, such as organizational commitment, organizational citizenship behavior, job satisfaction, In this paper, based on the relevant literatures, hypotheses are established and empirically tested that are about the effect of mentoring functions on the motivation to adopt knowledge, and the effect of motivation to adopt knowledge on the success of knowledge transfer. Using a sample of 287 service industry employees, the empirical results shows that career development and role modeling functions ware positively related to motivation to adopt knowledge, but psychosocial function was not significantly related. In addition, the motivation to adopt knowledge was positively related to the success of knowledge transfer. Based on these findings, implication and future direction are discussed.

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Numerical Optimization of Heat Transfer Surfaces with Staggered Ribs (엇갈린 리브가 부착된 열전달면의 수치최적설계)

  • Kim, Hong-Min;Kim, Kwang-Yong
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.735-740
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    • 2003
  • In this study, a numerical optimization to find the optimal shape of streamwise periodic ribs mounted on both of the principal walls is performed to enhance turbulent heat transfer in a rectangular channel. The optimization is based on Navier-Stokes analysis of flow and heat transfer with $k-{\varepsilon}$ turbulence model and is implemented using response surface method. The width-to-height ratio of a rib, rib height-to-channel height ratio, rib pitch to rib height ratio and distance between opposite ribs to rib height ratio are chosen as design variables. The object function is defined as a function of heat transfer coefficient and friction drag coefficient with weighting factor. Optimum shapes of the rib have been investigated for the range of 0.0 to 0.1 of weighting factor.

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