• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.546-552
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• 2012

This paper is a study on squeal noise simulation under the consideration of temperature and pressure dependent material properties of friction material. For this, data of pressure and temperature dependent material properties of lining is achieved by using lining data base and exponential curve fit. Complex eigenvalue analysis is performed for predicting squeal noise frequency and instability and chassis dynamo test is performed for achieving squeal noise frequency, sound pressure level, occurrence temperature & pressure. Initial multi models are composed for considering complex interface conditions such as pad ear-clip, piston-housing and guide pin-torque member. The simulation result of base models is compared with the test result. Squeal noise simulation under the consideration of temperature and pressure dependent material properties of friction material is performed and analyzed using multi models. And additional condition is disc material property variation. Entire simulation conditions are combined and analyzed. Finally, this paper proposes direction of the warm squeal noise model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.676-681
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• 2001

We usually divide the noise of exhaust system into pulsation noise and flow noise. Pulsation noise is the shock wave to occur when the burning gas of low pressure emits and include harmonic having basic frequency as the exhaust cycle of engine. Flow noise is the noise that is produced when gas flow emits into the atmosphere through the pipe and has the character of frequency like pink noise which has the high level of high frequency component. A muffler is divided into reflective type and absorptive type. We usually use the muffler compounding the property of them. In this study, it is the case of transfer matrix method that a muffler is compounded to analyze the elements of each section according to sound wave's proceed direction. But we use simple model. So, we use finite element method that takes short time to analyze. Acoustic analysis gives us transfer matrix to use FEA of SYSNOISE and we use STAR-CD for fluid analysis. We made database that is based on analytical results about the muffler of expansion type, extended type, offset type, reverse type, and perforated type and developed the muffler design system to perform work efficiently.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.10
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• pp.928-934
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• 2013

In this paper, the vibration characteristics of the trapezoidally corrugated plate are investigated by the analytical method. The corrugated plate is widely used as the structural elements because of its high stiffness and light weight. Because the corrugated plate is flexible in the corrugation direction and stiff in the transverse direction, it is treated as an equivalent orthotropic plate to analyze the corrugated plate simply. This equivalent plate must include both extensional and flexural effect to obtain the precise solution. The effective extensional and flexural stiffness of the equivalent plate are derived to consider these effects in the analysis. To demonstrate the validity of the proposed approach, the comparison is made with the previously published results and ANSYS solutions. Some numerical results are presented to check the effect of the geometric properties.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.342-345
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• 2005

To detect external acoustic signal, fiber optic sensor array using Fabry-Perot interferometer which had benefit of minimize and light-weight was used. The sensor head has 1cm in length, total length of fiber is 9.5cm, and the sensor supported at both ends, simply. External sound applied in lateral direction and detected two signals were compared each other. It was confirmed that the Fabry-Perot interferometric sensor array detected acoustic signal, effectively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.5
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• pp.537-544
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• 2009

In order to increase the critical speed of rotating disks of which functional material could not be changed such as in optical and magnetic data storage disks, a new disk with a rim reinforced by composite material is proposed and its concept is verified by numerical analysis. Stress distributions are found for the rotating disk composed of two annular disks of which materials are isotropic inside and orthotropic outside. Dynamic equation is formulated in order to calculate the natural frequency and critical speed. For the solution of lateral vibration, a rotational symmertry condition is applied along circumferential direction and a finite element interpolation with Hermite polynomial is performed along the radial direction to obtain a proper solution. According to the results, reinforcing a disk at rim makes critical speeds drastically increased, and induces a buckling phenomenon in mode (0,0) which occurs over the lowest critical speed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.820-823
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• 2007

In the wavenumber domain, each point on a radiation sphere indicates a plane wave of the frequency corresponding to radius of the sphere and the position on the sphere shows propagating direction of the plane wave. This concept is extended from the research by Choi[1] where he focus acoustic potential energy at a point on a radiation sphere. Here we propose the method to focus the energy at a point on the radiation sphere, as a result, we can easily generate a plane wave which propagates to any direction that we want.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1241-1246
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• 2007

In recent years, the semiconductor industry and the optical industry are developed rapidly. The recent demands have expanded for optical components such as the optical lens, the optical semiconductor and the measuring instrument. Object transport systems are driven typically by the magnetic field and the conveyer belt. Recent industry requires more faster and efficient transport system. However, conventional transport systems are not adequate for transportation of optical elements and semiconductors. The conveyor belts can damage precision optical elements by the contact force and magnetic systems can destroy the inner structure of semiconductor by the magnetic field. In this paper, the levitation transport system using ultrasonic wave is developed for transporting precision elements without damages. The steady state flexural vibration of the beam is expressed using Euler-Bernoulli beam theory. The transport direction of an object is examined according to phase difference and frequency. The theoretical results are verified by experiments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.788-793
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• 2002

Hybrid type slim tilt actuator and 6-wire supported are developed for DVD recording in the optical disc drive of notebook PC, which can compensate the inclination of disc and objective lens. The hybrid actuator uses the actuating method of moving coil in the focus and track direction and that of moving magnet in the tilt direction. Comparing with 6-wire supported actuator and hybrid type actuator, we can choose an actuator for slim super combo pickup. Two actuator are designed through the modal analysis and magnetic field analysis and experimental results shows dynamic characteristics. Finally, it is verified that the actuator can compensate the disc tilt of ${\pm}0.4^{\circ}$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.140-145
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• 2002

In high-capacity disk drives with ever-growing track density, the allowable level of position error signal (PES) is becoming smaller and smaller. A substantial portion of the PES is caused by disk vibration. This can be reduced by using a head gimbal assemblies (HGAs) that do not confine the slider movement to the vertical direction to disks, but allow movement to the radial direction of disks with respect to disk vibration. Several types of HGAs are proposed for such radial motion of the slider. Experimental results show that the PES levels are reduced by the proposed HGA-design concepts.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.593-598
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• 2009

In this study we present results for the design of ground test system for 4 degree of freedom(DOF) control test is one of the smart UAV ground test. This system is equipped with real smart UAV and Z direction DOF and 3 direction rotation DOF, Ensuring safe operation of the Smart UAV is a top priority. To this end, it is required to do structure analysis and test verification to confirm the design margin and safety. Based on the analysis, the ground test system has been redesigned to meet the structural conditions.