• Journal of the Korean Magnetic Resonance Society
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• v.4 no.2
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• pp.103-115
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• 2000

Wavelet transforms are introduced as a new tool to distinguish real peaks from the noise contaminated NMR data in this paper. New algorithms of two wavelet transforms including Daubechies wavelet transform as a discrete and orthogonal wavelet transform (DWT) and Morlet wavelet transform as a continuous and nonorthogonal wavelet transform(CWT) were developed fer noise elimination. DWT and CWT method were successfully applied to the noise reduction in spectrum. The inevitable distortion of NMR spectral baseline and the imperfection in noise elimination were observed in DWT method while CWT method gives a better baseline ahape and a well noise suppressed spectrum.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.433-438
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• 2011

Doosan has been developing a 5MW class gas turbine engine, DGT-5. Campbell diagram has been used for prediction of possible occurrence of resonances of rotating machinery. The Campbell diagram consists of blade natural frequency and excitation frequency. In this paper, modal characteristics of compressor and turbine blades are investigated and Campbell diagram is obtained. We calculated compressor and turbine blade's natural frequency using ANSYS tool. The result has been verified through test.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.203-208
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• 2000

The vibration of a mask degrades the color purity in CRT Therefore, a damping wire is put into contact with the mask to reduce the vibration in perfectly flat CRT. In this study, we analyzed the vibration of the mask contacting with the damping wire using FEM. First we calculated the natural frequencies and mode shapes of the mask by modal analysis, and compared them with the measured results to confirm our finite element model. The modal analysis of the wire was also performed to investigate resonance with the mask. Finally, the transient dynamic analysis of the mask contacting with the wire was performed. The vibration of the mask was measured to confirm our analysis, and the results are in good agreement with the analysis.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.7-12
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• 2008

In the design of modem rotating machinery, it is often necessary to increase the performance of rotor-bearing system. Since a critical speed range influences the performance and safety of the whole system, it should be necessary to constrain the critical speed and thus resonance response in design process to result in large vibration. Consequently the minimization of resonance response amplitudes within the operation range of the rotor system becomes the most primary design objective. In this paper, based on the assumption that the external shape of rotating-shaft, bearing supporting positions and etc, the natural frequency analysis of spindle is performed by ANSYS $10.0^{(R)}$ Optimum design is conducted using the RBF model.

• Journal of the Korean Magnetic Resonance Society
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• v.24 no.1
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• pp.23-29
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• 2020

Mozart's music has been suggested to affect spatio-temporal reasoning of listeners, which has been called "Mozart effect". However, the effects of Mazart's music on human metabolism have not been known. We dissected Mozart's music into its compositional elements and studied their effects on metabolism of experimental animals. Mozart music significantly reduced cortisol level induced by stress. NMR metabolomic study revealed different urine metabolic profile according to the listening to Mozart's music. In addition, each element of music exhibited different metabolic profile. Functional MRI study also showed enhanced brain activity upon listening to Mozart's music. Taken together, Mozart's music seems to be related with brain activity, stress hormone and whole body metabolism.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.4
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• pp.115-118
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• 2018

Dipyrromethane 2 functionalized with 3-chloropropyl group on the meso carbon undergoes an unusual intramolecular electrophilic aromatic substitution reaction in the presence of $NaN_3$ instead of a simple nucleophilic substitution reaction. As a result, a new chiral dipyrromethane 1 was synthesized. In this reaction, the ${\beta}$-carbon of the pyrrole ring functions as a nucleophile while the carbon next to the chlorine atom acts as an electrophile. Interestingly, this reaction progresses even in the absence of an acid catalyst. Compound 1 was fully characterized by $^1H-^1H$ and $^1H-^{13}C$ COSY NMR spectroscopic analyses and the high resolution EI mass spectrometry.

• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.213-217
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• 2008

The flux-lock type superconducting fault current limiter(SFCL) can apply the magnetic field into the high-$T_C$ superconducting(HTSC) element by adopting the magnetic field coil in its third winding. To apply the magnetic field into the HTSC element effectively, the capacitor for LC resonance is connected in series with the magnetic field coil. However, the current waveform of third winding for the application of the magnetic field is affected by the LC resonance condition for the frequency of the source voltage and can affect the waveform of the limited fault current. In this paper, the current waveform of the third winding in the flux-lock type SFCL according to LC resonance condition during a fault period was analyzed. From the differential equation for its electrical circuit, the current equation of the third winding was derived and described with the natural frequency and the damping ratio as design parameters. Through the analysis according to the design parameters of the third winding, the waveform of the limited fault current was confirmed to be influenced by the current waveform of the third winding and the design condition for the stable fault current limiting operation of this SFCL was obtained.

• Journal of the Korean Magnetic Resonance Society
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• v.4 no.1
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• pp.29-40
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• 2000

Coupled carbon-13 relaxation study of 1,1,1-trichloroethane dissolved in DMSO has been performed to gain some crucial insight into the dynamics of methyl group in this compound. For this purpose the relaxation behaviors of several observable magnetization modes for CH3 spin system generated by various perturbing pulse sequences have been carefully investigated and various dipolar spectral densities were estimated by nonlinear numerical fittings of the observed data with the relaxation curves, which were then employed to determine the three principal values for the diffusion tensor for end-over-end molecular rotation as well as internal rotational parameters of methyl group. In this process we could uniquely determine two correlation times $\tau$int(1) and $\tau$int(2) which give valuable information on internal rotor dynamics and thus obtained data were interpreted on the basis of various proposed models for internal rotation. compound undergoes three-fold jumps at 25$^{\circ}$. The fact that the ratio $\tau$int(1) / $\tau$int(2) is close to 1.0 may be interpreted as indicating that methyl group in this C.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.2
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• pp.216-222
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• 2013

A solar power generator is usually installed outdoors and it is exposed to extreme environments such as heavy fall of snow and high speed wind. Therefore, the solar tracker structure should be designed to have sufficient static and dynamic stiffness against such environmental conditions. In this paper, eigenvalue analysis of the solar tracker is carried out by varying the pose of the solar panel and unsteady flow analysis around a single tracker or multi-trackers arranged in a line is performed by varying the parameters such as wind directions, wind speeds and the pose of the solar panel to evaluate whether there exists an instability of resonance due to vortex shedding. Finite element eigenvalue analysis shows that natural frequencies and modes are almost not influenced by the pose of the solar panel and the finite element flow analysis shows that there does not exist periodic vortex shedding due to the flow around single tracker or multiple solar trackers in a line.

• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1233-1242
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• 2008

The hydration effect on the intrinsic magnetism of natural salmon double-strand DNA was explored using electron magnetic resonance (EMR) spectroscopy and superconducting quantum interference device (SQUID) magnetic measurements. We learned from this study that the magnetic properties of DNA are roughly classified into two distinct groups depending on their water content: One group is of higher water content in the range of 2.6-24 water molecules per nucleotide (wpn), where all the EMR parameters and SQUID susceptibilities are dominated by spin species experiencing quasi one-dimensional diffusive motion and are independent of the water content. The other group is of lower water content in the range of 1.4-0.5 wpn. In this group, the magnetic properties are most probably dominated by cyclotron motion of spin species along the helical π -way, which is possible when the momentum scattering time (${\tau}_k$) is long enough not only to satisfy the cyclotron resonance condition (${\omega}_c{\tau}_k$ > 1) but also to induce a constructive interference between the neighboring double helices. The same effect is reflected in the S-shaped magnetization-magnetic field strength (M-H) curves superimposed with the linear background obtained by SQUID measurements, which leads to larger susceptibilities at 1000 G when compared with the values at 10,000 G. In particular, we propose that the spin-orbital coupling and Faraday's mutual inductive effect can be utilized to interpret the dimensional crossover of spin motions from quasi 1D in the hydrate state to 3D in the dry state of dsDNA.