• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.337-343
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• 2012

This work investigates the vibrational characteristics of the underground gas pipelines. Experiments were conducted to analyze the effects of various parameters on the vibrational characteristics from the emergency detection point of view. Influences of the various types of impact exerted on the pipe, height of free fall and measuring locations were analyzed. Especially, the difference between the vibrational signal generated by the direct impact on the pipe and the ambient noise was successfully identified. To validate the experimental observation, computer simulation was also performed with constant properties(elasticity, fluid velocity and internal pressure) which are directly conjectured from the accompanying experiment with a real pipe system.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.4
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• pp.47-55
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• 1990

This study is the first step for the grasp of transfer path to the vibration generated from the automotive engine and consideration of counterplan for optimal design and low vibration, low noise of the exhaust system. In this study, by applying the theory of modal analysis and experiment, vibrational reduction effect is evaluated according to the attachment of flexible coupling to the exhaust system. And data for the design is suggested to improve the characteristics of vibration. The vibration isolation and damping characteristics are improved due to the attachment of flexible coupling to the exhaust system. As a result, it is identified that flexible coupling which has good flexibility is more effective for the improvement of vibrational characteristics. By the estimation of modeshape of vibration, the location of optimal damping hanger is determined in the viewpoint of vibration isolation. Also it is confirmed that the characteristics of vibration is improved due to the attachment of damping hanger.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.11a
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• pp.1-2
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• 2000

In chip plating, several parameters must be taken into consideration. Current density, solution concentration, pH, solution temperature, components volume, chip and media ratio, barrel geometrical shape were most likely found to have an effect to the process yields. The 3 types of barrels utilized in chip plating industry are the onventional rotating barrel, vibrational barrel(vibarrel), and the centrifugal type. Conventional rotating barrel is a close type and is commonly used. The components inside the barrel are circulated by the barrel's rotation at a horizontal axis. Process yield has known to have higher thickness deviation. The vibrational barrel is an open type which offers a wide exposure to electrolyte resulting to a stable thickness deviation. It rotates in a vertical axis coupled with multi-vibration action to facilitate mixed up and easy transportation of components. The centrifugal barrel has its plated work centrifugally compacted against the cathode ring for superior electrical contact with simultaneous rotary motion. This experiment has determined the effect of barrel vibration intensity to the plating thickness distribution. The procedures carried out in the experiment involved the overall plating process., cleaning, rinse, Nickel plating, Tin-Lead plating. Plating time was adjusted to meet the required specification. All other parameters were maintained constant. Two trials were performed to confirm the consistency of the result. The thickness data of the experiment conducted showed thatbthe average mean value obtained from higher vibrational intensity is nearer to the standard mean. The distribution curve shown has a narrower specification limits and it has a reduced variation around the target value. Generally, intensity control in vi-barrel facilitates mixed up and easy transportation of components. However, it is desirable to maintain an optimum vibration intensity to prevent solution intrusion into the chips' internal electrode. A cathodic reaction can occur in the interface of the external and internal electrode. 2H20 + e $\rightarrow$M/TEX> 20H + H2.. Hydrogen can penetrate into the body and create pressure which can cause cracks. At high intensity, the chip's motion becomes stronger, its contact between each other is delayed and so plating action is being controlled. However, the strong impact created by its collision can damage the external electrode's structure there by resulting to bad plating condition.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3771-3776
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• 2010

The dynamics of the $CN^-$-ligated ferric cytochrome c (CytcCN) in $D_2O$ at 283 K following Q-band photoexcitation at 575 nm was observed using femtosecond time-resolved vibrational spectroscopy. The equilibrium vibrational spectrum of the CN stretching mode of CytcCN shows two overlapping bands: one main band (82%) at $2122\;cm^{-1}$ with $23\;cm^{-1}$ full width at half maximum (fwhm) and the other band (18%) at $2116\;cm^{-1}$ with $7\;cm^{-1}$ fwhm. The time-resolved spectra show bleaching of the CN fundamental mode of CytcCN and two absorption features at lower energies. The bleach signal and both absorption features are all formed within the time resolution of the experiment (< 200 fs) and decay with a life time of 1.9 ps. One transient absorption feature, appearing immediately red to the bleach signal, results from the thermal excitation of low-frequency modes of the heme that anharmonically couple to the CN fundamental mode, thereby shifting the CN mode to lower energies. The shift of the CN mode decays with a lifetime of 2 ps, equivalent to the time scale for vibrational cooling of the low-frequency heme modes. The other transient absorption feature, which is 3.3 times weaker than the bleach signal and shifted $27\;cm^{-1}$ toward lower energies, is attributed to the CN mode in an electronically excited state where the CN bond is weakened with a lowered extinction coefficient. These observations suggest that photoexcited CytcCN mainly undergoes ultrafast radiationless relaxation, causing photo-deligation of $CN^-$ from CytcCN highly inefficient. As also observed in $CN^-$-ligated myoglobin, inefficient ligand photodissociation might be a general property of $CN^-$-ligated ferric hemes.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3553-3560
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• 2010

A new hydrazone derivative compound has been synthesized and characterized by IR, $^1H$-NMR, $^{13}C$-NMR and UV-vis. spectroscopy techniques, elemental analysis and single-crystal X-ray diffraction (XRD). The new compound crystallizes in monoclinic space group C2/c. In addition to the crystal structure from X-ray experiment, the molecular geometry, vibrational frequencies and frontier molecular orbitals analysis of the title compound in the ground state have been calculated by using the HF/6-31G(d, p), B3LYP/6-311G(d, p) and B3LYP/6-31G(d, p) methods. The computed vibrational frequencies are used to determine the types of molecular motions associated with each of the observed experimental bands. To determine conformational flexibility, molecular energy profile of (1) was obtained by semi-empirical (AM1) calculation with respect to a selected degree of torsional freedom, which was varied from $-180^{\circ}$ to $+180^{\circ}$ in steps of $10^{\circ}$. Molecular electrostatic potential of the compound was also performed by the theoretical method.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.321-325
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• 2000

To obtain precise surface and high productivity, high speed end milling has been studied recently. Though high speed end milling is explicitly effective for precision surface generation geometrically, tool deflection, chatter vibration and frequency characteristics of end milling system deteriorate the theoretical surface. In this study, simulation algorithm and programming method are suggested to simulate machined surface using acceleration signal in high speed end milling. This simulation is conducted by considering vibrational effect of spindle system which was not considered by other researchers. Between simulated results and experiment results, good agreements were obtained.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.11
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• pp.1097-1102
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• 2010

In this paper, the energy flow analysis(EFA) of the body-in-white door of a real automotive was performed using the energy flow finite element method(EFFEM) to effectively predict the vibrational responses of built-up structures in the medium to high frequency range. To increase the validity of EFA results, the structural hysteresis damping loss factor was measured by the experiment using the concept of statistical energy analysis(SEA). As the excitation frequency increases, the predicted results simulated with EFFEM generally agree with the experimental results.

• Journal of Biomedical Engineering Research
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• v.39 no.5
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• pp.183-187
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• 2018

In this paper, we investigated the efficiency according to the output transmission method of the round window driving type AMEIs (active middle ear implants) through the cadaveric experiment. For the experiment, we fabricated DRT (direct rod transducer) and FMT (floating mass transducer) type vibrational transducers based on our previous studies and conducted their output characteristics were measured. TCBT (tri-coil bellows transducer) and DFMT (differential floating mass transducer) were implemented with the same driving force and electrical characteristics as one of DRT and FMT, respectively. In the experiment using three human temporal bone, normal stapes vibration was measured with 1 Pa in front of tympanic membrane, and then was compared with each output of transducers. From the comparison, the DRT type vibration transducer was superior in overall energy transfer efficiency, especially in the low frequency range. There was no difference in implantation difficulty between the two transducers. The results of this study suggest that the DRT type vibrational transducer is more efficient and needs further study to overcome the low frequency degradation in round window approaching with FMT.

• Journal of the Ergonomics Society of Korea
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• v.32 no.4
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• pp.345-353
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• 2013

Objective: This research measured physiological and psychological effects of Vibroacoustic stimulation(VA) to scapular and sacrum of supine position on the mattress. Background: When vibroacoustic stimulation applies to human body, it has a positive influence on physiological and psychological effects by stimulating the organs, tissues and cells of whole body. Method: This experiment was conducted to 10 normal males in two conditions: no stimulation and vibroacoustic stimulation. No stimulation experiment was executed as a supine position for 30 minutes without any vibrational stimulus, while vibroacoustic stimulation was transmitted by the vibrational speaker, which uses 40Hz frequency. Subjects had a laser Doppler flowmeter probe in scapular, sacrum, and also had 8 channel electroencephalogram(EEG) measurement sensor in the scalp. Blood pressure and skin temperature were measured in two conditions with an underlying posture for 30 minutes. Additionally, blood flow rate and EEG were measured before and after for two minutes on two conditions. Results: According to the vibroacoustic stimulation, blood flow rate and skin temperature were increased, while blood pressure was decreased. When using vibroacoustic stimulation compared to no stimulation, blood flow rate went approximately two times higher, and skin temperature also higher 3~4 times. Furthermore, the relative alpha power of brain wave was significantly increased when we applied to vibroacoustic stimulation. Conclusion: This experiment tested the VAT embedded in mattress in two conditions. According to this experiment, VAT decreases blood pressure, improves not only a physiological effect on blood flow rate as well as skin temperature, but also psychological functions by increasing relative alpha power. Application: The results of the publishing trend analysis might help physiological and psychological effects of vibroacoustic stimulation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.10a
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• pp.15-15
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• 1999

In chip plating, several parameters must be taken into consideration. Current density, solution concentration, pH, solution temperature, components volume, chip and media ratio, barrel geometrical shape were most likely found to have an effect to the process yields. The 3 types of barrels utilized in chip plating industry are the conventional rotating barrel. vibrational barrel (vibarrel), and the centrifugal type. Conventional rotating barrel is a close type and is commonly used. The components inside the barrel are circulated by the barrel's rotation at a horizontal axis. Process yield has known to have higher thickness deviation. The vibrational barrel is an open type which offers a wide exposure to electrolyte resulting to a stable thickness deviation. It rotates in a vertical axis coupled with multi-vibration action to facilitate mixed up and easy transportation of components, The centrifugal barrel has its plated work centrifugally compacted against the cathode ring for superior electrical contact with simultaneous rotary motion. This experiment has determined the effect of barrel vibration intensity to the plating thickness distribution. The procedures carried out in the experiment involved the overall plating process., cleaning, rinse, Nickel plating, Tin-Lead plating. Plating time was adjusted to meet the required specification. All other parameters were maintained constant. Two trials were performed to confirm the consistency of the result. The thickness data of the experiment conducted showed that the average mean value obtained from higher vibrational intensity is nearer to the standard mean. The distribution curve shown has a narrower specification limits and it has a reduced variation around the target value, Generally, intensity control in vi-barrel facilitates mixed up and easy transportation of components, However, it is desirable to maintain an optimum vibration intensity to prevent solution intrusion into the chips' internal electrode. A cathodic reaction can occur in the interface of the external and internal electrode. $2HD{\;}+{\;}e{\;}{\rightarrow}20H{\;}+{\;}H_2$ Hydrogen can penetrate into the body and create pressure which can cause cracks. At high intensity, the chip's motion becomes stronger, its contact between each other is delayed and so plating action is being controlled. However, the strong impact created by its collision can damage the external electrode's structure thereby resulting to bad plating condition. 1 lot of chip was divided into two equal partion. Each portion was loaded to the same barrel one after the other. Nickel plating and tin-lead plating was performed in the same station. Portion A maintained the normal barrel vibration intensity and portion B vibration intensity was increased two steps higher. All other parameters, current, solution condition were maintained constant. Generally, plating method find procedures were carried out in a best way to maintained the best plating condition. After plating, samples were taken out from each portion. molded and polished. Plating thickness was investigated for both. To check consistency of results. 2nd trial was done now using different lot of another characteristics.