• Title/Summary/Keyword: Transfer function 전달함수

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Inverse Radiation Analysis of a Two-Dimensional Irregular Geometry Using Unstructured Triangular Meshes (비정렬 삼각 격자를 이용한 2 차원 비직교 형상에서의 역복사 해석)

  • Yi, Kyung-Joo;Baek, Seung-Wook;Kim, Man-Young
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.6
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    • pp.561-567
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    • 2011
  • The inverse radiation analysis of a two-dimensional irregular configuration using unstructured triangular meshes is presented. In this study, an enclosure filled with an absorbing, emitting and scattering medium with diffusely emitting and reflecting opaque boundaries is considered. The finite volume method is applied to solve the radiative transfer equation in order to simulate the measured incident radiation values which are used as input data for the inverse analysis. The conjugate gradient method is adopted for the estimation of wall emissivities by minimizing the objective function at each iteration step. To verify the performance of the unstructured grid system, we compare the results with those using a structured grid system for the two-dimensional lopsided shape. The effect of measurement errors on the estimation accuracy is also investigated.

Accuracy Simulation of Precision Rotary Motion Systems (회전운동 시스템의 정밀도 시뮬레이션 기술)

  • Hwang, Joo-Ho;Shim, Jong-Youp;Hong, Seong-Wook;Lee, Deug-Woo
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.3
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    • pp.285-291
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    • 2011
  • The error motion of a machine tool spindle directly affects the surface errors of machined parts. The error motions of the spindle are not desired errors in the three linear direction motions and two rotating motions. Those are usually due to the imperfect of bearings, stiffness of spindle, assembly errors, external force or unbalance of rotors. The error motions of the spindle have been needed to be decreased to desired goal of spindle's performance. The level of error motion is needed to be estimated during the design and assembly process of the spindle. In this paper, the estimation method for the five degree of freedom (5 D.O.F) error motions of the spindle is suggested. To estimate the error motions of the spindle, waviness of shaft and bearings, external force model was used as input data. And, the estimation models are considering geometric relationship and force equilibrium of the five degree of the freedom. To calculate error motions of the spindle, not only imperfection of the shaft, bearings, such as rolling element bearing, hydrostatic bearing, and aerostatic bearing, but also driving elements such as worm, pulley, and direct driving motor systems, were considered.

Experimental contribution analysis of external aeroacoustic noise sources to interior noise of automobile (자동차 외부 공기음향 소음원들의 실험적 실내 기여도 분석 기술 개발)

  • Lee, Myung Han;Ih, Kang Duck;Hwang, Seongil;Kim, Yong-Joe
    • The Journal of the Acoustical Society of Korea
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    • v.37 no.5
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    • pp.300-308
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    • 2018
  • The contribution analysis of various external aeroacoustic noise sources to interior noise is important, enabling to design an automobile with a low interior noise level. With a new technique, the CD (Cholesky Decomposition), it is proposed to decompose an overall interior noise spectrum into multiple spectra, each representing the contribution of a specific noise source to the interior noise. In order to validate this method, three kinds of experiments were conducted. Furthermore, it is proposed to improve the CD-based contribution analysis method to be integrated with existing exterior microphone arrays in the wind tunnel. This method was validated with an experiment with two speakers.

Evaluation of Dose Reduction and Maintaining Image Quality according to Exposure Factors of Cone Beam Computed Tomography (콘빔전산화단층촬영에서 노출 조건에 따른 화질 유지 및 선량 감소에 대한 평가)

  • Han, Jin-Woo
    • Journal of the Korean Society of Radiology
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    • v.14 no.4
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    • pp.353-360
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    • 2020
  • This research aims at suggesting exposure condition that shows maintaining the value of the physical image quality factor by decreasing tube voltage and tube current from the standard exposure condition(80 kV, 7 mA) of a CBCT apparatus. To measure the value of the physical image quality factor, modular transfer function(MTF) was analyzed and dose-area product(DAP) was used for the measurement of exposure dose. CBCT images of a Sedentex IQ phantom were obtained under 15 exposure conditions of different combination of tube voltage(80, 78, 76 kV) and tube current(7, 6, 5, 4, 3 mA) and MTF 10 was calculated under each exposure conditions. There were no significant differences in MTF 10 under 80 kV-6 mA, 80 kV-5 mA exposure conditions in comparison with standard exposure condition. Based on the results of this research, 80 kV-5 mA condition are expected to be able to reduce exposure dose with maintaining the value of the physical image quality factor of the standard exposure condition.

Effect of Flame Resistant Treatment on The Sound Absorption Capability of Sawdust-mandarin Peel Composite Particleboard (방염처리가 톱밥-귤박 혼합파티클보드의 흡음성능에 미치는 영향)

  • Kang, Chunwon;Jin, Taiquan;Kang, Ho-Yang
    • Journal of the Korean Wood Science and Technology
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    • v.43 no.4
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    • pp.511-517
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    • 2015
  • Sound absorption capability of the flame resistant treated sawdust-mandarin peel composite particleboard was were estimated by two microphone transfer function methods. The weight of flame resistant treated board slightly increased by the treatment. The treatment improved fire retardant performance by decreasing the charred area of flame resistant treated board. Sound absorption capabilities of flame resistant treated sawdust-mandarin peel composite particleboard, in the entire estimated frequency range of 500-6,400 Hz was slightly lower than those of the control specimen. Sound absorption capability of both the control and flame resistant treated sawdust-mandarin peel composite particleboards were higher than that of commercial gypsum boards, being widely used as a sound absorber for ceiling at the estimated frequency.

Mechanical Properties and Sound Absorption Capability of Shipbuilding Plywood Waste (조선산업 폐합판의 강도적 성질과 흡음성능)

  • Kang, Chun-Won;Kim, Gwang-Chul;Park, Hee-Jun;Kang, Wook
    • Journal of the Korean Wood Science and Technology
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    • v.38 no.6
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    • pp.457-462
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    • 2010
  • Sound absorption capability and bending strength of laminated ship-building plywood waste of maple and melanti wood were estimated. Sound absorption coefficients of wood had been measured by the two microphone transfer function method and bending strength examined by three point loading. The maximum strength in bending of laminated ship-building plywood waste of maple and melanti wood were 534 and 414 kgf/$cm^2$, respectively. The sound absorption coefficients of laminated ship-building plywood waste were higher than mongolian oak and fiber board, well used construction material. Especially, in the case of laminated ship-building plywood waste of melanti wood, average sound absorption coefficient was about 0.25. It was surmised that the laminated ship-building plywood waste can be used as interior materials because of its good mechanical and sound absorption properties.

Analysis of the Crankshaft Behavior on In-plane and Out-plane Mode at the Firing Stage (엔진 운전시 크랭크샤프트의 면내.외 모드의 거동 해석)

  • Abu Aminudin;Lee, Hae-Jin;Lee, Jung-Youn;Oh, Jae-Eung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.4 s.109
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    • pp.319-328
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    • 2006
  • This paper presents a method for analysis of the mechanical behavior of a crankshaft in a four-cylinder internal combustion engine. The purpose of the analysis was to study the characteristics of the shaft in which the pin and arm parts were assumed to have a uniform section in order to simplify the modal analysis. The results of natural frequency transfer function and mode shape were compared with those obtained by experimental work. The results obtained from the comparison showed a good agreement with each other and consequently verified the analysis model. Furthermore, a prediction of crankshaft characteristics under the firing condition, by using the model, was performed. This study describes a new method for analyzing the dynamic behavior of crankshaft vibrations in the frequency domain based on the initial firing stages. The new method used RMS values to calculate the energy at each bearing journal and counter weight shape modification under the operating conditions.

Identification of Structural Defects in Rail Fastening Systems Using Flexural Wave Propagation (굽힘파 전파 특성을 이용한 레일체결장치의 구조 결함 진단)

  • Park, Jeongwon;Park, Junhong
    • Journal of the Korean Society for Nondestructive Testing
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    • v.34 no.1
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    • pp.38-43
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    • 2014
  • An experimental method based on flexural wave propagation is proposed for identification of structural damage in rail fastening systems. The vibration of a rail clamped and supported by viscoelastic pads is significantly influenced by dynamic support properties. Formation of a defect in the rail fastening system induces changes in the flexural wave propagation characteristics owning to the discontinuity in the structural properties. In this study, frequency-dependent support stiffness was measured to monitor this change by a transfer function method. The sensitivity of wave propagation on the defect was measured from the potential energy stored in a continuously supported rail. Further, the damage index was defined as a correlation coefficient between the change in the support stiffness and the sensitivity. The defect location was identified from the calculated damage index.

Forward-Looking Ultrasound Imaging Transducer : I. Analysis and Design (전향 초음파 영상 트랜스듀서 : I. 해석 및 설계)

  • Lee, Chan-Kil
    • The Journal of the Acoustical Society of Korea
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    • v.14 no.2E
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    • pp.73-86
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    • 1995
  • The transducer section of the forward-looking ultrasound imaging catheter (FLUIC) consists of a circular piezoelectric element as a vibrator and a conical acoustic mirror as a perfect reflector. A small diameter piezoelectric transducer element is mounted on the side of a catheter's rotating shaft. The unique design of FLUIC provides the capability to form a two-dimensional image of a cross-section of vessel in front of the catheter, which is lacking in the present generation of intravascular ultrasound (IVUS) transducers, as well as a conventional side view image. The mirror configuration for the transducer section of the FLUIC is designed using an approximated ray tracing techniques. The diffraction transfer function approach [1] developed for the field prediction from primary sources is generalized and extended to predict the secondary diffraction characterstics from an acoustic mirror. The extended model is verified by simulation and experiment through a simple plane reflector and employed to analyzed the field characteristics of a FLUIC.

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A Personal Web-Agent System Using Case-Based Learning (사례기반 학습을 이용한 개인형 웹 에이젼트 시스템)

  • Kim, Young-Kwon;Lee, Jae-Pil;Lee, Mal-Rey;Kim, Kyung-Man;Kim, Ki-Tae
    • The Transactions of the Korea Information Processing Society
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    • v.5 no.6
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    • pp.1583-1592
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    • 1998
  • Recently, massive amount of infonnation is provided for the internet users. So users want to search information on Internet, but it is difficult to search information what you want. In this paper, we propose a personal Web-agent system using Case-based learning, Web-Guide. Web-Guide consists of two sub-system, interface-system and learning-system. Interface-system operates other web-browser nearly the same and connects user to system. And interface-system transfer datas of current page to learning-queue. Learning-system visit and evaluate the value of each page in learning-queue using evaluation-function that gave weight values occupied by analyzing tag used the character of HTML document. After all users who are known about artificial intelligence well and not made experiments by using Web-Guide, they reached their desired sites faster than before.

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