• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.418-425
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• 2013

In this study, the three scents effects on subjects due to EEG type, and it researched to find optimal scent to increase their amenity and productivity. EEG and HRV were compared and analyzed in the environmental test room by classifying subjects into two type: A and B. The condition of the environmental test room was in temperature 31[$^{\circ}C$], relative humidity 50[RH%], air current speed 0.02[m/s] and illuminance 1000[lux] with setting up three different scents which are Rosemary, Jasmine and Hazelnut. The result of this study, at Jasmine scent for A and B type, relative ${\alpha}$ wave, SEF50, $\frac{SMR}{\theta}$ and SDNN were revitalized, and ${\alpha}$ wave asymmetry index, HRT, stress index and fatigue degree were decreased. It was found that favorite scent of A and B type is same as Jasmine scent, but A type was more sensitive than B type about scent. Therefore Jasmine scent is very effective to increase amenity, productivity and concentration, and to decrease stress and fatigue degree.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.4
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• pp.71-77
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• 2007

In this study, reactions of central nervous systems working against different conditions of forced frequency and acceleration were measured and analyzed. The experiment are conducted with health men. The steady vibration conditions of forced frequency (0.315m/s2-1.0Hz, 0.315m/s2-10Hz and 10Hz-1.0m/s2) are used and the waves of EEG (Electroencephalogram) are measured. As a result, this paper shows that the ${\alpha}-wave$ of frontal lobe transfers from low to high frequency band under the vibration environment. Additionally, the average frequency of ${\alpha}-wave$ is higher under the vibration than under non-vibration environment. In the case of forced frequency of 1.0Hz-0.315m/s2, the feeling with the vibration are nearly same compared with the non-vibration condition. But in the case of 10Hz-1.0m/s2, uncomfortable feeling increased compared with the non-vibration condition. This study also shows the relationship between fluctuation slop and feeling. From this study, it is found that the effect of vibration on human depends on acceleration characteristics. Highly accelerating vibration is more harmful to human.

• The Journal of Engineering Geology
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• v.23 no.4
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• pp.503-510
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• 2013

Shear wave velocity is widely used as an parameter for investigating subsurface characteristics and for obtaining the design parameters based on theoretical equations. This study seeks to estimate the coefficient of shear wave velocity in Busan clay via laboratory tests. Eight specimens were extracted at depths of 10, 12, 15, 20, 22, 25, 30, and 31 m. The specimens were subjected to the consolidation test to determine the relationship between effective stress and shear wave velocity. The relationship shows a non-linear trend and is similar to the results of a previous study. The coefficient shows constant coverage and a relationship between ${\alpha}$ and ${\beta}$ is suggested. The results demonstrate that this coefficient could be used as a reference value to determine engineering parameters based on the shear wave velocity.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2724-2726
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• 2002

The effect which electromagnetic wave has influence on visual activity of human, was investigated in this study. The EEG and the EOG generated by the rays of LED were measured in shield room when the subject were exposed at electromagnetic wave(820MHz, 2mV) or not exposed. Each component of the EEG was compared and evaluated on being exposed at electromagnetic wave or not. As a result was $\alpha$ wave was represented relatively low level in the case of exposed at electromagnetic wave and $\beta$ wave was represented relatively low level in the case of not exposed.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.114-121
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• 2004

Frictional heating in brakes causes thermoelastic distortion of the contacting bodies and hence affects the contact pressure distribution. The resulting thermo-mechanical coupling can cause thermoelastic instability (TEI) if the sliding speed is sufficiently high, leading to non-uniform heating called hot spots and low frequency vibration known as hot judder. The vibration of brakes to the known phenomenon of frictionally-excited thermoelastic instability is estimated studying the interface temperature and pressure evolution with time. A simple model has been considered where a layer with half-thickness$\alpha$slides with speed V between two half-planes which are rigid and non-conducting. The advantage of this properlysimple model permits us to deduce analytically the critical conditions for the onset of instability, which is the relation between the critical speed and the growth rate of the interface temperature and pressure. Symmetrical component of pressure and temperature distribution at the layer interfaces can be more unstable than antisymmetrical component. As the thickness $\alpha$ reduces, the system becomes more apt to thermoelastic instability. For perturbations with wave number smaller than the critical$m_{cr}$ the temperature increases with m vice versa for perturbations with wave number larges than $m_{cr}$ , the temperature decreases with m.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.4
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• pp.527-534
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• 2010

Purpose : The application of tape to modulation of pain and muscular excitability has become common clinical practice among musculoskeletal physical therapy. However, the techniques of the tape application has been relied on empirical evidence in preference to the neurophysiological evidence. Thus, the mechanism of taping has to be elucidated further. The aim of this study was to determine whether elastic and non-elastic taping across a muscle does indeed change ${\alpha}$-motor neuron excitability. Methods : The study was performed on 10 neurologically healthy adults. Two different types of tape were applied to skin overlying gastrocnemius. The elastic tape stretched up to 120% of its original length but non-elastic tape didn't stretched up of its original length. The tape applied across the direction on thickest part of the gastrocnemius. The ${\alpha}$-motor neuron excitability of the gastrocnemius was assessed using the gastrocnemius H-reflex. The amplitude of the M-wave and H-reflex were measured across three conditions: before tape application, with tape and with the tape removed. Results : No significant changes of the excitability of the ${\alpha}$-motor neuron were obtained across three condition, either in the elastic and non-elastic tape. Conclusion : From the results, I could come to the conclusion that further clinical work will be required.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.1
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• pp.63-69
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• 2015

PURPOSE: Low-intensity exercise with transient restriction of blood flow to muscle could be an alternative rehabilitation method which avoids the problems associated with conventional high-intensity exercise. However, the mechanism of low-intensity exercise with transient restriction of blood flow is not clearly known. Thus, the purpose of this study was to investigate the mechanism of improvement of muscular function after low-intensity exercise with transient restriction of blood flow using H-reflex analysis. METHODS: Twenty one healthy young adults with no medical history of neurological or musculoskeletal disorder voluntarily participated in this study. The ${\alpha}$-motor neuron excitability of the triceps surae was assessed using the H-reflex. The amplitude of the M-wave and H-reflex were measured across three conditions: rest, after low-intensity exercise without restriction of blood flow and after low-intensity exercise with restriction of blood flow. The subjects performed low-intensity ankle plantar flexion exercise at their own pace for one minute without or with transient restriction of blood flow achieved by a sphygmomanometer cuff on popliteal fossa at a pressure of 120mm of mercury(120 mmHg). RESULTS: No significant changes of the excitability of the ${\alpha}$-motor neuron were obtained across three different conditions. CONCLUSION: This study found that low-intensity exercise with transient restriction of blood flow did not influence to ${\alpha}$-motor neuron excitability of the triceps surae. From the results, I could come to the conclusion that further study will be required.

• Journal of the Korean Magnetics Society
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• v.26 no.4
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• pp.115-118
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• 2016

We investigated the magnetocrystalline anisotropy of pure ${\alpha}^{{\prime}{\prime}}-Fe_{16}N_2$ by using full-potential linearized augmented plane wave method (FLAPW). A very high magnetic moment was obtained for Fe (4d) site due to the lattice expansion in the z-direction, while the magnetic moment of Fe (4e) and (8h) site were suppressed due to hybridization with neighboring N atom. The calculated spin magnetic moments for different Fe sites (4d, 4e and 8h) were in good agreement with previously reported values. Due to the tetragonal distortion, we found a very large uniaxial anisotropy constant of $0.58MJ/m^3$. Besides, a high value of magnetization of 1.76MA/m was obtained. In additon, the estimated coercive field and maximum energy product of 6.51 kOe and 71.7 MGOe were obtained for pure ${\alpha}^{{\prime}{\prime}}-Fe_{16}N_2$. This may suggest that the ${\alpha}^{{\prime}{\prime}}-Fe_{16}N_2$ can be utilized for potential rare-earth free permanent magnet material.

• Journal of KSNVE
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• v.5 no.2
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• pp.207-213
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• 1995

A new predictor-corrector explicit time integration algorithm is presented for solving structural dynamics problems. The basis of the algorithm is the implicit generalized-.alpha. method recently developed by the authors. Like its implicit parent, the explicit generalized-$\alpha$ method is a one- parameter family of algorithms in which the parameter defines the high-frequency numerical dissipation. The algorithm can be utilized effectively for linear and nonlinear structural dynamics calculations is which numerical dissipation is needed to reduce spurious oscillations inherent in non-dissipative time integration methods used to solve wave propagation problems.

• Journal of Information Display
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• v.10 no.2
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• pp.72-75
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• 2009

The Brillouin spectrum of 4'-n-pentyl-4-cyano-biphenyl (5CB) liquid crystals homogeneously confined in a planar liquid crystal (LC) cell was measured using a 6-pass tandem Fabry-Perot interferometer. By adopting a special right-angle scattering geometry, the sound velocity of 5CB was estimated from the Brillouin shift without knowing the refractive index. The sound velocity of the longitudinal wave propagating along the direction of the directors aligned parallel to the glass plates of the LC cell was 1784${\pm}$7 m/s at 300 K. The attenuation coefficient $\alpha$ was estimated to be approximately $1.9{\times}10^6m^{-1}$, which is about twice as large as that of the longitudinal sound wave propagating along the direction perpendicular to the directors. The present method may be very useful in the evaluation of the elastic properties of the materials used in display devices, whose refractive indices are not known.