• 한국소음진동공학회논문집
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• 제23권10호
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• pp.902-908
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• 2013

The input torque ripple induced by combustion engines is a significant source of NVH(noise, vibration and harshness) problem in automotive transmissions. Because this torque fluctuation is primarily transmitted to the input shaft of automotive powertrains(e.g., automatic transmissions) when the lock-up clutches are closed, a torsional damper with helical springs is generally inserted between engine and transmissions to isolate the input vibratory energy, which is essential for the passenger comfort. The torsional vibration isolator exhibits frequency ranges in which there is low vibration transmissibility. However, the isolation performance is currently evaluated through the static torsional spring characteristics. In this study, the transmissibility of torsional spring dampers, essential dynamic performance index for vibration isolator, is first experimentally evaluated.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 춘계학술대회 논문집
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• pp.407-408
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• 2010

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2196-2199
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• 1997

In the industrial motor drive system, a shaft torsional vibration is often generated when a motor and a load are connected with a flexible shaft. This paper treats the vibration suppression control of such a system. In this paper, a control system design method using Linear Matrix Inequality (LMI), which is a tool for control design that replaces or complements Lyapunov-Riccati equations, is provided and a $H_{\infty}$ speed controller for a induction motor by LMI is proposed. In the $H_{\infty}$ speed controller, weights are used to satisfy tracking and disturbance rejection. Experimental results show the validity of the proposed $H_{\infty}$ speed controller by LMI, and this controller is compared with the state feedback controller.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.336-339
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• 2007

A sensor having capability to measure two different kinds of ultrasonic waves selectively is described. Under the same bias field configuration, this magnetostrictive type sensor can selectively measure longitudinal waves and flexural ones. Since the switching operation of mode selection is made only by changing the polarity of the permanent magnets used to configure the bias field, it will be very useful after the permanent magnet are interchanged with electromagnets. In order to find the optimal operating bias field, finite elements analysis is used and the condition for flexural wave measurements to meet is found. The linearity of the sensor is verified by experiments and the requirements for linearity also are proposed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1042-1048
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• 2007

This work analytically investigated the radiated noise of a helical gear-housing system due to the excitation of helical gears. The helical gears were modeled as a 12-degree of freedom mass-spring-damper system; the shaft was modeled as a rod, a beam, and a torsional shaft; and the gear housing was modeled as a clamped circular plate with viscous damping. The modeling of this system used transfer matrices for helical gears, shafts, and bearings. Damping for both the bearings and the plate were obtained by modal testing. For the evaluation of noise, sound pressure from the plate due to the force and the moment in both radial and tangential directions was analytically derived by the Rayleigh integral. The analytical derivation and parameters from the experiment were applied to an analysis of noise for the two sets of helical gears with differing gear ratios. The analysis showed that the moment excitation in both helical gears contributed more to the noise of the plate than axial force excitation.

• 화약ㆍ발파
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• 제16권3호
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• pp.25-34
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• 1998

This area is covered in Andesite of high compression strength and located in PUSAN SEO-KU. There are many old houses around shaft site. So, we must have a cautious blasting operation. A total of 40 blasts were test at DAE-SHIN Shaft site to study the magnitude and frequency characterization of blast-induced vibration. The effect of viblating frequency on structual damage and site-specific scaling to define th empirical equations were also discussed. The result can be summarized as follows: 1. Some empirical equations were obtained. $V=K\{{\frac{D}{W}}1/3\}^{-n}$ where the values for n and K are estimated to be -1.407 to -2.202 and 643.3489 to 7283.2104 respectively. 2. Dominant frequencies at short distance are in the range of about 75.0 to 91.8 Hz, with some exceptions of about 50Hz, Frequencies observed at long distance are in the range of 10 to 2Hz. It is apparent the shift of dominant frequency down to lower levels at long distance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.360-364
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• 2001

본 논문에서는 최근의 진화적 구조최적화(ESO) 전략을 회전축의 형상최적화에 적용하였으며, 각 계산 스텝마다 단위 유한요소의 크기를 변경함으로써 기존의 방법보다 빠르고 정확한 최적형상에 수렴하는 새로운 방법을 제시하였다. 축요소의 직경을 시스템 설계변수로 하였으며, 축중량의 감소, 공진배율(Q-factor)의 감소 및 충분한 위험속도의 분리여유를 갖도록 목적함수를 설정하였다. 불평형응답 및 굽힙응력의 구속조건을 부가하였으며, 목적함수에 대한 설계변수의 감도해석을 수행하였다. 전동기축계에 대한 적용 결과로부터 주파수와 동적 구속조건하의 로터베어링 시스템에 대한 축 형상 최적화에 ESO법이 효과적으로 이용될 수 있음을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.365-370
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• 2001

The purpose of this work is to suggest a new non-contact measurement method applicable to the diagnosis of rotating shafts. Longitudinal elastic waves propagating along the shafts are measured by magnetostrictive sensors that make use of the coupling phenomena between strains and magnetic induction in ferromagnetic shafts. These sensors have been successfully applied in pipes and others, but it appears that the present application of them to rotating shafts is made here for the first time. Several isssues appearing in the present application are carefully investigated and several experimental results are presented to address the usefulness of the present method.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1513-1520
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• 2000

Complex modal testing method for rotating disks with support motion is introduced which handles the pairs of two point excitation and responses of the disk as complex input and output, respectively. This method utilizes the directivity information and the separation over the rotational speed of forward and backward traveling wave modes or bending coupled modes in the directional frequency response functions(dFRFs). This method synthesizes the normal/reverse dFRFs and complex wave dFRF, which were originally applied to rotating shaft and rotating disk, respectively, and is applied to complex system with dynamically coupled rotating disks and shaft. Experiments with a commercial hard disk drive spindle system demonstrate the validity of this method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.515-517
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• 1997

In the industrial motor drive system, a shaft torsional vibration is often generated when a motor and a load are connected with a flexible shaft. This paper treats the vibration suppression control of such a system. In this paper, two-degree-of-freedom(TDOF) control of the two-mass resonant system using the $H_{\infty}$ filter is proposed. TDOF control method satisfies the command following property and the internal stability at the same. The $H_{\infty}$ filter is robust in noise and disturbance. Simulation results show the validity of the proposed control method.