• Smart Structures and Systems
• /
• v.30 no.6
• /
• pp.639-648
• /
• 2022

This study aims at numerically and experimentally investigating torsional guided wave mixing with weak material nonlinearity under acoustoelastic effect in tubular structures. The acoustoelastic effect on single central frequency guided wave propagation in structures has been well-established. However, the acoustoelastic on guided wave mixing has not been fully explored. This study employs a three-dimensional (3D) finite element (FE) model to simulate the effect of stress on guided wave mixing in tubular structures. The nonlinear strain energy function and theory of incremental deformation are implemented in the 3D FE model to simulate the guided wave mixing with weak material nonlinearity under acoustoelastic effect. Experiments are carried out to measure the nonlinear features, such as combinational harmonics and second harmonics in related to different levels of applied stresses. The experimental results are compared with the 3D FE simulation. The results show that the generation combinational harmonic at sum frequency provides valuable stress information for tubular structures, and also useful for damage diagnosis. The findings of this study provide physical insights into the effect of applied stresses on the combinational harmonic generation due to wave mixing. The results are important for applying the guided wave mixing for in-situ monitoring of structures, which are subjected to different levels of loadings under operational condition.

• Journal of the Korean Society of Fashion and Beauty
• /
• v.3 no.3 s.3
• /
• pp.56-63
• /
• 2005

In the study of permanent waving method after mixing ample and permanent wave solvent in permanent wave the dyed humans hair are as follows; First, Permanent waving method after mixing ample and permanent wave solvent is that the better effective way in permanent wave the dyed humans hair because permanent waving cycle is constant and hair cuticle is glossy. Second, This study is not interpret in permanent wave dyed humans hair that tensile strength is effect of permanent waving method after mixing ample and permanent wave solvent. A extension degree is effect of permanent waving method after mixing ample and permanent wave solvent use indifferent ample treatment method. Third, Hair cuticle damages are a little permanent waving method after mixing ample and permanent wave solvent in permanent wave dyed humans hair.

• Journal of the korean society of oceanography
• /
• v.39 no.1
• /
• pp.35-45
• /
• 2004

Based on the MASNUM wave-current coupled model, the temperature and salinity structures along $36^{\circ}N$ in the Yellow Sea are simulated and compared with observations. Both the position and strength of the simulated thermocline are similar to data analysis. The wave-induced mixing is strongest in winter and plays a key role in the formation of the upper mixed layer in spring and summer. Numerical experiments suggest that in the coastal area, wave-induced mixing and tidal mixing control the vertical structure of temperature and salinity.

• Korean Journal of Optics and Photonics
• /
• v.10 no.4
• /
• pp.294-300
• /
• 1999

The density matrix is solved more rigorously, compared with the third-order pertubation method used in the conventional theory, for a semiconductor laser amplifier. Then the coupled wave equations are derived to explain the wavelength conversion due to the spectral hole burning in the semiconductor optical amplifier. It is shown that our results can explain the effect of saturation of the population density on the electric polarization, which affects the four-wave mixing and wavelength conversion, better than the conventional theroy where the third-order pertubation is used.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.11
• /
• pp.919-925
• /
• 2016

In this study, the Lamb wave mixing technique, which is basised on advanced research on the nonlinear bulk wave mixing technique, is applied for corrosion detection. To demonstrate the validity of the Lamb wave mixing technique, an experiment was performed with normal and corroded specimens. Comparison group in an experimentation are selected to mode and frequency with dominant in-plane displacement and out-of-plane displacement of Lamb waves. The results showed that the Lamb wave mixing technique can monitor corrosion defects, and it has a trend similar to that of the conventional Lamb wave technique. It was confirmed that the dominant displacement and mode matching the theory were generated. Flaw detectability is determined depending on displacement ratio instead of using the measurement method and mode selection.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.36 no.1
• /
• pp.53-59
• /
• 2016

Ultrasonic nonlinear evaluation is generally utilized for detection of not only defects but also microdamage such as corrosion and plastic deformation. Nonlinearity is determined by the amplitude ratio of primary wave second harmonic wave, and the results of its comparison are used for evaluation. Owing to the experimental features, the experimental nonlinearity result contains system nonlinearity and material nonlinearity. System nonlinearity is that which is unwanted by the user; hence, it acts as an error and interrupts analysis. In this study, a bulk wave mixing technique is implemented in order to minimize the system nonlinearity and obtain the reliable analysis results. The biggest advantage of this technique is that experimental nonlinearity contains less system nonlinearity than that for the conventional nonlinear ultrasonic technique. Theoretical and experimental verifications are performed in this study. By comparing the results of the bulk wave mixing technique with those of the conventional technique, the strengths, weaknesses, and application validity of the bulk wave mixing technique are determined.

• Journal of the Optical Society of Korea
• /
• v.5 no.1
• /
• pp.20-24
• /
• 2001

Non-destructive measurement of zero-dispersion wavelength variation in a dispersion shifted fiber by four-wave mixing technique is carried out. The oscillatory behavior of the four-wave mixing efficiency is utilized for the measurement of the linear dispersion slope and zero-dispersion wavelength. A simple formula useful for engineering estimation of the characteristics of fiber four-wave mixing efficiency is presented.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.25 no.4
• /
• pp.460-466
• /
• 1988

In this paper, the theory and experiments on the one-way optical image transmission through optical fiber by using degenerate four wave mixing in BSO single crystal are demonstrated. From the theoretical analysis, the diffraction efficiency of phase conjugate wave in BSO single crystal is greatly dependent on applied electric field intensity, diffraction grating period formed in the crystal and incident beam ratio, those are also in good agreement with the experimental results. Based on the experimental results, we have arranged the typical degenerate four wave mixing system in the optimal conditions (applied electric field, E. = 5kV/cm` diffraction grating period, 3\ulcorner` beam ratio of backward pump wave versus signal wave, 2.7) and realized one-way optical image transmission system through optical fiber using BSO single crystal.

• Proceedings of the Optical Society of Korea Conference
• /
• 2006.02a
• /
• pp.245-246
• /
• 2006

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.12 no.4
• /
• pp.190-194
• /
• 2000

Dispersion coefficient influenced by the wave parameters was derived analytically using the vertical velocity distribution based on linear wave theory. It is the depth- and wave period-averaged value and shows larger values in deep water condition than in shallow water condition. It also shows the general pattern of the dispersion coefficient in the oscillatory flows, i.e. it converges the specific value as the wave period is much larger than the vertical mixing time but it approaches zcro as the wave period is much smaller than the vertical mixing time. The dispersion coefficient derived in the condition of the simple assumption have to be modified in order to consider the shallow water condition or the real condition.