• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.3
• /
• pp.80-85
• /
• 2012

The ultrasonic cutting method is which cutting by applying high frequency vibrational energy into specific area at constant pressure. Ultrasonic cutting is consisted of power supply, transducer, booster and cutting tool. Precise designing is required since each part's shape, length and mass can affect driving frequency and vibration mode. This paper focused to cutting tool design, its length L was set by calculating vibration equation. And the value of the shape parameter a was diversified as the integral multiple and the result of 40,189Hz the analysis of Modal was shown in the length 30mm of the result of performance b in the 11th mode Also by performing harmonic response analysis, the frequency response result was 40,189Hz, which was similar to modal analysis result.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.04a
• /
• pp.735-741
• /
• 2008

Identification of asymmetry and anisotropy of rotor system is important for diagnosis of rotating machinery. Directional frequency response functions (dFRFs) are known to be a powerful tool in effectively detecting the presence of asymmetry or anisotropy. In this paper, an input noise effect of dFRFs for rotors is estimated, when both asymmetry and anisotropy are present. The normalized random errors of the dFRFs are calculated to verify the validity of the method, which is demonstrated by numerical simulation with a simple rotor model.

• Proceedings of the IEEK Conference
• /
• 1999.06a
• /
• pp.69-72
• /
• 1999

In this paper, an efficient time domain equalization algorithm for discrete wavelet multitone(DWMT) data transmission is developed. In this algorithm, the time domain equalizer(TEQ) consists of two stages, i.e., the channel impulse response shortening equalizer(TEQ-S) in the first stage and the channel frequency flattening equalizer(TEQ-F) in the second stage. TEQ-S reduces the length of transmission channel impulse response to decrease intersymbol interference(ISI) followed by TEQ-F that enhances the channel frequency response characteristics to the level of an ideal channel, hence diminishes the bit error rate. TEQ-S is implemented using the least-squares(LS) method, while TEQ-F is designed by using the least mean-square(LMS) algorithm. Since DWMT system also requires of the frequency domain equalizer in order to further reduce ICI and ISI the hardware complexity is an another concern. However, by adopting an well designed and trained TEQ, the hardware complexity of the whole DWMT system can be greatly reduced.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.05a
• /
• pp.931-936
• /
• 2004

In this paper, vibration endurance test is carried out on rubber insulators used fur vehicle air cleaners. Based on the test results, endurance characteristics depending on type and material of the insulators are estimated. Frequency response characteristics of the air cleaner system are investigated to identify the cause of wear and failure in the insulators occurred during the endurance test. New insulator models with improved endurance characteristics are proposed by changing the frequency response property of the air cleaner system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.05a
• /
• pp.681-686
• /
• 2004

Identification of asymmetry and anisotropy of rotor system is important for diagnosis of rotating machinery. Directional frequency response functions (dFRFs) are known to be powerful tool in effectively detecting the presence of asymmetry or anisotropy. In this paper, an estimation method of dFRFs for rotors is newly developed, when both asymmetry and anisotropy are present. The method transforms the finite degrees-of-freedom time-varying linear differential equation of motion to an infinite degree-of-freedom time-invariant linear one, employing the modulated coordinates. The validity of the method is demonstrated by numerical simulation with a simple rotor model.

• Tribology and Lubricants
• /
• v.15 no.1
• /
• pp.68-76
• /
• 1999

This paper presents the nonlinear characteristics of the oil lubricated hydrodynamic journal bearing. The traditional approach is to characterize the behavior and performance of fluid film hydrodynamic journal bearings by means of linearized bearing analysis. The objective of this paper is to examine the nonlinear characteristics of the journal bearing when an external sinusoidal shock is given to the system. The oil film force is obtained by solving the finite width Reynolds equation at each time step by the solution of the column method. Frequency response function and journal orbit obtained from both linear and nonlinear bearing simulations are compared with each other.

• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.364-369
• /
• 1987

It has recently shown that a solenoid valve can be utilized in a hydraulic position-control system by discontinuous control methods. The objective of this study is to investigate the effects of solenoid valves on the response characteristics of a hydraulic position-control system by applying two kinds of discontinued control methods i.e., Simple On-Off (SOF) and Pusating On-Off(POF) controls. Three types of solenoid valves i.e. low-frequency, closed-center type (LF/C), high-frequency, closed-center type (HF/C), low-frequency, tandem-center type(LF/T) were used in this study. Effects of loading conditions and control parameters on the response characteristics were experimentally examined and compared each other. Pressure transients within the actuator were also studied.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.4
• /
• pp.90-96
• /
• 2012

The forced vibration response characteristics of a elastically restrained pipe conveying fluid with attached mass are investigated in this paper. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using Hamilton's principle. The effects of attached mass and spring constant on the forced vibration characteristics of pipe at conveying fluid are studied. The forced deflection response of pipe with attached mass due to the variation of fluid velocity is also presented. The deflection response is the mid-span deflection of the pipe. The dimensionless forcing frequency is the range from 0 to 16 which is the first natural frequency of the pipe.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.5
• /
• pp.541-549
• /
• 2007

In the case of control for mechanical systems, it is highly useful to be able to provide a compact model of the mechanical system to control engineers using the smallest number of state variables, while still providing an accurate model. The reduced mechanical model can then be inserted into the complete system models and used for extended system-level dynamic simulation. In this paper, moment-matching based model order reductions (MOR) using Krylov subspaces, which reduce the number of degrees of freedom of an original finite element model via the Arnoldi process, are presented to study the eigenvalue and frequency response problems of a HDD actuator and suspension system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.831-835
• /
• 2003

The objective of this paper is to suggest an experimental technique to measure the out-of-plane vibration intensity of a coupled plate. In order to measure the out-of-plane vibration intensity of the plate, the frequency response technique has been implemented. In this technique, the 2-D intensity vector at a measurement point has been estimate from the frequency response functions measured at 4 points in the neighborhood of the measurement point. The experimental result has been compared with a theoretical result. It showed that the experimental technique can be effectively used to measure the out-of-plane vibration intensity of plates.