Abstract: In conventional machining, cutting conditions such as cutting speed, feed rate, and depth of
the cut have great influence on the surface roughness. In micro machining, however, the surface shape
is affected by not only the machining parameters mentioned earlier but also tool stiffness, system
stability, and workpiece properties caused by the miniatured structure and cutting tool. Especially, in
a micro-machine system, the difference between the cutting forces in the recursive cuts introduces the
vibration easily. A high spindle causes instability of the system, increases the temperature in the
cutting process, and also changes the tool’s shape. This study introduces a method to predict the
surface shape of the workpiece based on the machining conditions in micro milling. The micro-milled
surfaces in different machining conditions are predicted by a computer simulation including the
vibration model and the simulated results show good agreement with the experimental results.
Abstract: The railway contact wire, which supplies electric railways with electric power, plays an
important role in determining the maximum railway velocity. In general, the maximum allowable
velocity of an electric railway is less than seventy percent of the wave propagation velocity of the
contact wire. Because the contact wire is more a beam model with dispersive wave characteristics
than a string model, the wave propagation velocity depends on the frequency. For this reason, there
have been only few studies on the wave propagation of the contact wire. In this paper, we proposed
two useful methods for estimating the wave propagation velocity of the railway contact wire by using
the Gabor wavelet transform on the experimental signals. In the first method, the ridges of wavelet
transform, which contain the essential information about dispersive characteristics, are used.
Specifically, the wave propagation velocity of the contact wire can be extracted from the time
difference of the wavelet ridges of the measured signals. In the second method, the cross-correlation
analysis of each wavelet transform is used to extract the wave propagation. The selection of the
optimal Gabor shaping factor for the best time-frequency localization by using the Shannon entropy
cost function is also discussed.
Abstract: As the home appliances are systemized, they have complicatedly assembled structure. It is
reasonable to see the noise problem of home appliance in the viewpoint of system like vehicle and
ship. There are various system analysis methods to resolve the noise problem [1-3]. To use system
analysis methods, the system information like modal and path properties must be gathered and analyzed.
But it takes many times to find out the system properties, so the simpler system analysis methods are
needed. The coherence analysis method is useful as the system analysis method, since the method can
identify the system property like the relationship between inputs and outputs directly and simply.
In the paper, the partial coherence analysis is used for identification of the MISO system of washing
machine, in which multi-input signals are vibration signals of motor bracket and an output signal is
noise signal of washing machine. The relationship between the noise of washing machine and the
vibration of the motor bracket in working status was identified and the parts of bracket closely
correlated with noise were also proved by the relationship. And the noise of washing machine was
controlled by redesigning the parts of bracket associated with the noise of washing machine based on
the coherence function in octave band.
Abstract: The existence of a crack in a structure produces changes in modal parameters of it such
as natural frequencies, damping, displacement and strain mode shapes. This paper is focused on
characterization of crack detection methods using strain mode shapes. To characterize crack
detection methods, we changed sensing grids from corner grid to cross grid and geometry of the
specimens from rectangular to triangular plate. Rest of conditions was fixed. For crack detection
criteria, COMAC, ECOMAC, ADSM and new method have been used and the results are compared
with each other. The COMAC, ECOMAC and ADSM showed limited capacity of crack detection
on plates but the new method gave good results in 90% of all cases.
Abstract: This research investigates the vibration caused by ball bearing in a HDD spindle system,
specifically non-repeatable runout (NRRO), at elevated temperature by analyzing the characteristics
of ball bearing and the natural vibration characteristics of the spindle system due to the effect of
elevated temperature. It shows that the elevated temperature results in the decrease of bearing
deformation in the spindle system, which reduces the bearing stiffness and the natural frequencies of
the spindle system consequently. It has a significant effect on the amplitude and the frequency
distribution of NRRO at elevated temperature.
Abstract: The aim of this paper is to propose a robust method for extracting damping ratios of a
railway contact wire using a continuous wavelet transform (CWT). It is hard to measure the damping
ratios of the contact wire because the contact wire has close natural modes in a low frequency range
and the dynamic signals of the contact wire gathered in the field are easily corrupted by extraneous
noises. The proper choice of the wavelet parameters to decouple the close modes is required in order
to obtain accurate damping ratios for the railway contact wire. In this paper, we investigated CWT
error terms and derived a relation between a frequency resolution and complex Morlet wavelet
parameters. In order to show the accuracy of the proposed method, we extracted damping ratios for
the simulated pure and noisy signals which have close natural modes. According to the results, the
proposed method can provide the damping ratios well agreed with true ones even for the noisy data.
Finally, we applied the proposed method to the contact wire of a conventional railway line in Korea in
order to verify the applicability in the field. The damping ratios extracted from the real data were in
the range from 0.01 to 0.04.
Abstract: In examining particulate deposits in the pipes within a chemical vapor deposition (CVD)
system, vibration diagnostics is compared and studied against ultrasonic diagnostics. The latter
method involves pulsing the outer wall of pipes with an ultrasonic sensor and analyzing the
resulting echo to observe particulate deposits inside pipes. Vibration diagnostics examines the
existence of particulate deposits by analyzing the difference in the frequencies generated when a
vibrator is adhered to the outer wall of pipes. With ultrasonic diagnostics, good test results were
obtained only when particulate deposits were attached to the inner wall of the pipes. After some
time, however, particulate deposits were not detected properly, as the ultrasonic wave failed to cross
the fine gaps created between the inner wall of the pipe and the deposits. In conclusion, the
vibration diagnostics is being expected as the effective method in monitoring the particulate
deposits inside pipes in the CVD system where the desired behavior is reduced frequency along
with the the particulate deposits in comparison to the case where the pipe is clean.
Abstract: The image of a semi-circular blockage and location in the uniform and stepped pipe was
reconstructed by measuring the eigen-frequency shift of the resonance and anti-resonance
frequencies of multi-sine acoustic waves. In this study we have used different boundary conditions
from previous works of Wu and Fricke  and De Salis and Oldham  to determine the blockage
cross-sectional area and position. The results agreed with real fractional cross sectional area and
position in the both continuous and stepped pipes. New approach showed a better quality of
reconstructed image with small ripple number and the false dummy blockage signal was also
reduced. The present method of blockage image reconstruction is a noninvasive nondestructive and
can meet the integrity evaluation implementation for all types of transmission pipeline
Abstract: Nonlinear modeling method for the structural dynamic analysis of a micro cantilever beam
actuated by electrostatic force is presented in this study. Static deflection is first obtained by solving
nonlinear static equilibrium equation and the modal and the stability characteristics are calculated at
the static equilibrium position. It is found that the amplitude and the frequency of the applied
electrostatic voltage influence the stability of the structure significantly.
Abstract: Flexible structures undertaking impact while undergoing overall motion can be found in
several industrial products these days. Transient motion and stress induced by impact should be
considered elaborately to extend the life of the products. In the present study, a modeling method for a
flexible beam with a tip mass that undertakes impact while undergoes large overall motion is
presented. The tip mass takes the impact force and the transient responses of the beam are calculated
by employing the assumed mode method. The stiffness variation caused by the large overall motion is
considered in this modeling. The effects of the tip mass and the angular speed of the beam on the
transient responses are investigated.