• Title, Summary, Keyword: Transfer functions

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Transfer Path Analysis of vibration and noise for medical air compressor using PAK system (PAK system 을 이용한 의료용 컴프레서의 진동.소음 전달경로 해석)

  • Kang, Kwi-Hyun;Kang, Jin-Chul;Park, Chun-Kwon;Lee, Jeong-Hwan;Oh, Jae-Eung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1000-1004
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    • 2008
  • As performance of medical air compressor improve, the problem of noise increased. Noise is very important to medical air compressor because most of this installed inside of building. The main goal of this paper is show TPA (Transfer Path Analysis) result for contribution analysis using PAK system. Generally, the conventional TPA method consists of two steps. First, transfer functions between output sound and sources are measured by excitation experiment. Second, transferred sound in each transfer path is generated by multiplying the transfer function and the sound source signal. Then, if the output sound synthesized from all transferred sounds doesn't give good agreement with the measured output sound (i.e., the accuracies of the transfer functions are low), setting a suitable countermeasure guideline becomes difficult. For obtaining highly accurate transfer functions, eliminating correlations among transfer functions and noise included in the measured data are necessary. In the new method with PAK system, the vibration acceleration and sound signals around the sound sources and the output sound were measured simultaneously to obtain the transfer functions when compressor was operating. By applying PAK system, a highly accurate and efficient transfer path analysis method was developed that does not require an excitation experiment.

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Flight Dynamic Identification of a Model Helicopter Using CIFER® (III) - Transfer Function Analysis - (CIFER ® 를 이용한 무인 헬리콥터의 동특성 분석 (III) - 전달함수 해석 -)

  • Bae, Yeong-Hwan;Koo, Young-Mo
    • Journal of Biosystems Engineering
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    • v.37 no.3
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    • pp.192-200
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    • 2012
  • Purpose: Aerial application of chemicals with an agricultural helicopter allows for precise and timely spraying and reduces working labor and pollution. An attitude controller for an agricultural helicopter would be helpful to aerial application operator. The objectives of this paper are to determine the transfer function models and to estimate the handling qualities of a bare-airframe model helicopter. Methods: Transfer functions of a model unmanned helicopter were estimated by using NAVFIT and DERIVID modules of the $CIFER^{(R)}$ program to the time history data of frequency sweep flight tests. Control inputs of the transfer functions were elevator, aileron, rudder and collective pitch stick positions and the outputs were resulting on-axis movements of the fuselage. Results: Minimum realization of the transfer functions for pitch rate output to elevator control input and roll rate output to aileron control input produced second order transfer functions with undamped natural frequencies around 3.0 Hz and damping ratios of 0.139 and 0.530, respectively. The equivalent time delays of the transfer functions ranged from 0.16 to 0.44 second. Sensitivity analysis of the proposed parameters allowed derivation of minimal realization of the transfer functions. Conclusions: Handling quality of the model helicopter was addressed based on the eigenvalues of the transfer functions, corresponding undamped natural frequencies with damping ratios. The equivalent time delays of the lateral-directional motion ranged from 0.16 to 0.44 second, longer than the 0.1 to 0.15 second requirement for well-controlled typical manned aerial vehicles.

Transfer Function for Phytoavailable Heavy Metals in Contaminated Agricultural Soils: The Case of The Korean Agricultural Soils Affected by The Abandoned Mining Sites (중금속 오염 농경지의 식물유효태 예측 모델식 개발: 우리나라 폐광산 인근 농경지 토양 사례 연구)

  • Lim, Ga-Hee;Kim, Kye-Hoon;Seo, Byoung-Hwan;Kim, Kwon-Rae
    • Korean Journal of Environmental Agriculture
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    • v.33 no.4
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    • pp.271-281
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    • 2014
  • BACKGROUND: Application of the transfer functions derived from local soil data is necessary in order to develop proper management protocols for agricultural soils contaminated with heavy metals through phytoavailability control of the heavy metals. The aim of this study was to derive the transfer functions of Korean agricultural soils affected by the abandoned mining sites and evaluate suitability of the derived transfer functions. METHODS AND RESULTS: 142 agricultural soils affected by the abandoned mining sites were collected and analyzed. Two extraction methods, including 1 M $NH_4NO_3$ extraction and 0.01 M $Ca(NO_3)_2$ extraction were applied to determine phytoavailable metal pools in soils. Multiple stepwise regression of phytoavailable metal pools against the corresponding total metal concentration and soil properties was conducted to derive suitable transfer functions for estimating phytoavailable heavy metal pools. Applicability of the derived transfer functions was examined by calculating NME and NRMSE. CONCLUSION: Soil pH and organic matter were valid variables for derivation of the transfer functions which were applicable for estimating phytoavailable metal concentrations in the soils being contaminated by heavy metals. In addition, it was confirmed that transfer functions need to be developed based on local soil conditions to accurately estimate heavy metal-phytoavailability.

A Realization of Multidimensional Digital Filters by using the Triangular Decompostition of the Coefficient Matrix (계수행렬의 삼각분해에 의한 다차원 디지털 필터의 실현)

  • 김태수;김명기
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.14 no.2
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    • pp.95-107
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    • 1989
  • This paper proposes a realization method of multidimensional digital filters that has high modularity, regularity and parallelism enjoying the attributes for efficient VLSI implementation. The method shows that multidimensional transfer functions can be treated as two-dimensional transfer functions modifying the decomposition method of multidimensional transfer functions proposed by Venetsanopoulos etal, and then be displayed by multiplications and additions of one-dimensional transfer functions by applying the griangular decomposition theorem to the coefficient matrices of the two-dimensional transfer functions.

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Analysis of Dynamic Characteristics of Hydraulic Transmission Lines with Distributed Parameter Model (분포정수계 유압관로 모델의 동특성 해석)

  • Kim, Do Tae
    • Journal of Drive and Control
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    • v.15 no.4
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    • pp.67-73
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    • 2018
  • The paper deals with an approach to time domain simulation for closed end at the downstream of pipe, hydraulic lines terminating into a tank and series lines with change of cross sectional area. Time domain simulation of a fluid power systems containing hydraulic lines is very complex and difficult if the transfer functions consist of hyperbolic Bessel functions which is the case for the distributed parameter dissipative model. In this paper, the magnitudes and phases of the complex transfer functions of hydraulic lines are calculated, and the MATLAB Toolbox is used to formulate a rational polynomial approximation for these transfer functions in the frequency domain. The approximated transfer functions are accurate over a designated frequency range, and used to analyze the time domain response. This approach is usefully to simulate fluid power systems with hydraulic lines without to approximate the frequency dependent viscous friction.

Improved Transfer Functions for Modified Sheppard-Taylor Converter that Operates in CCM: Modeling and Application

  • Wang, Faqiang
    • Journal of Power Electronics
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    • v.17 no.4
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    • pp.884-891
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    • 2017
  • The improved transfer functions of the modified Sheppard-Taylor (MS-T) converter, which is capable of regulating output voltage under a wide range of input voltage and load variations, negligible current ripple, and fewer components in comparison to the Sheppard-Taylor (S-T) converter, operating in continuous conduction mode (CCM) are investigated in this study. Its DC equilibrium point, small signal model, and transfer functions are derived and analyzed. Then, the voltage controller is applied for this MS-T converter. The comparisons between the derived model and the existing model are presented. The hardware circuit is designed and the circuit experiments are provided for validation. The results show that the improved transfer functions of the MS-T converter are more effective and general than the previous ones for describing its real characteristics.

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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A Realization Method of the Transfer Functions Containing Variable Parameter

  • Kawakami, Atsushi
    • Proceedings of the IEEK Conference
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    • pp.1988-1991
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    • 2002
  • In this paper, we propose a method for realizing transfer functions containing variable parameter, by the state-space method. By using this method, variable transfer functions (VTF) can be often realized with a minimal dimension. In case that a minimal realization can not be obtained, the realization dimension can be fairly reduced.

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A Heat Release Model of Turbulent Premixed Flame Response to Acoustic Perturbations (유동 섭동에 의한 난류예혼합화염의 열발생 모델에 관한 연구)

  • Cho, Ju-Hyeong;Baek, Seung-Wook
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.6
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    • pp.413-420
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    • 2008
  • The unsteady heat release characteristics play a significant role in combustion instabilities observed in low emissions gas turbine combustors. Such combustion instabilities are often caused by coupling mechanisms between unsteady heat release rates and acoustic perturbations. A generalized model of the turbulent flame response to acoustic perturbations is analytically formulated by considering a distributed heat release along a curved mean flame front and using the flame's kinematic model that incorporates the turbulent flame development. The effects of the development of flame speed on the flame transfer functions are examined by calculating the transfer functions with a constant or developing flame speed. The flame transfer function due to velocity fluctuation shows that, when a developing flame speed is used, the transfer function magnitude decreases faster with Strouhal number than the results with a constant flame speed at low Strouhal numbers. The flame transfer function due to mixture ratio fluctuation, however, exhibits the opposite results: the transfer function magnitude with a developing flame speed increases faster than that with a constant flame speed at low Strouhal numbers. Oscillatory behaviors of both transfer function magnitudes are shown to be damped when a developing flame speed is used. Both transfer functions also show similar behaviors in the phase characteristics: The phases of both transfer functions with a developing flame speed increase more rapidly than those with a constant flame speed.

Measurement of Mechanical-acoustic Transfer Functions of Vehicles by Combination of Mechanical and Acoustic Excitations (구조가진과 음향 가진의 결합에 의한 차량의 구조-음향 전달 함수 측정)

  • 고강호;이장무
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.9
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    • pp.158-164
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    • 1999
  • In this paper a simple measurement technique for mechanical-acoustic transfer functions is proposed . The mechanical-acoustic transfer functions, generally , are measured through mechanical excitations ; impact hammers or shakers. Recently , by virtue of vibro-acoustical reciprocity principle, they are measured through acoustic excitations : loudspeakers. This kind of test needs to measure the volume velocity , the radiation characteristics of a sound source. Because the volume velocity of the sound source is changed by driving signal , it is difficult to measure it. However , the new method in this paper needs not to measure the volume velocity of a sound source by combination of mechanical and acoustic excitations. Moreover, this method has the methodological advantages, such as usage of a general loudspeaker for the reciprocal excitation, no sptatial limitations for measurements of mechanical-acoustic transfer functions.

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