• Macromolecular Research
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• v.15 no.5
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• pp.396-402
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• 2007

The dielectric properties and various pattern-forming states of dual-frequency material in a nematic phase, as well as its mixture containing low concentrations of reactive monomers, are reported. The dielectric relaxation behaviors of nematic MLC 2048 are presented and compared to its mixture containing both mesogenic and nonmesogenic reactive monomers. The sign-inversion frequency of the dielectric anisotropy was significantly shifted on the addition of small amounts of the reactive monomers. However, all three mixtures used in this study essentially exhibited the same field-induced instabilities at different frequencies and voltage domains of the applied electric field. A broad band of modulated states were found to exist above a critical voltage and within a voltage dependent frequency band in the vicinity of the sign-inversion frequency, $f_I$, of the dielectric anisotropy. As the $f_I$ of the mixtures shifted, so did the bands of the modulated state of the different mixtures and the temperatures, which were well matched with the measured $f_I$ value.

• Korean Journal of Adult Nursing
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• v.21 no.5
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• pp.458-467
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• 2009

Purpose: This study was object to the effects of a resistance exercise combined with relaxation therapy on blood pressure, frequency of exercise and physical fitness in elderly women. Methods: Seventy three elderly women participated in an exercise program for 12 months. The exercise program consisted of stretching, massage and resistance training using thera-bands twice a week and 50 minutes in every sessions each week. Repeated measures ANOVA were performed using SAS. Results: After the exercise program there was a significant difference in systolic blood pressure, frequency of exercise, body fat, sitting to standing, walking 2 minutes, sitting on a chair and reaching, and standing on one leg with eyes opened. After 6 months, there was a significant decrease in systolic blood pressure and significant increase in frequency of exercise, body fat, sitting to standing and standing on one leg with eyes opened. In 12 months, there was a significant increase in body fat, 2 minutes walking, and sitting in a chair and reaching. Conclusion: Resistance exercise combined with muscle relaxation therapy would have a positive effect on elderly women. We found that it was helpful for the elderly women in terms of physical fitness.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1469-1478
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• 2014

Use of acetonitrile in electrolytes promotes better operation of supercapacitors. Recent efforts show that electrolytes containing acetonitrile can also function in a wide range of operating temperatures. Therefore, this paper addresses the dielectric relaxation processes, structure and dynamic properties of the bulk acetonitrile at various temperatures. Systems of acetonitrile were modeled using canonical ensemble and simulated by employing Molecular Dynamics method. Results show that interactions among the molecules were correlated within a cut-off radius while parallel and anti-parallel arrangements are observed beyond this radius at relatively high and low temperatures respectively. Furthermore, effects of C-C-N and C-H bending modes were greatly appreciated on the power spectral density of time rate change of dipole-dipole correlations whereas frequency shifts were observed on all modes at the lowest temperature under consideration. Linear variations with temperature were depicted for reorientation times and self-diffusion coefficients. Shear viscosity was also computed with a good accuracy within a certain range of the temperature as well.

• Journal of radiological science and technology
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• v.30 no.2
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• pp.161-165
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• 2007

Ultrasonic absorption spectrum in bovine serum albumin aqueous solutions have been measured at $20^{\circ}C$ over the broad frequency range $0.2{\sim}1,000\;MHz$ at pH 7. The absorption spectrum observed at neutral pH was successfully analyzed with the distribution of relaxation time assuming a mirror-image curve of the Davidson-Cole function. This distribution function suggests that hydration of BSA molecules is responsible for the absorption.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.44 no.7
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• pp.901-907
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• 1995

The switching characteristics of As$_{10}$ Ge$_{15}$ Te$_{75}$ thin film were investigated under d.c. bias. And the frequency dependence of the conductivity was analysed with regard to the temperature dependence, in order to find the physical properties of the As$_{10}$ Ge$_{15}$ Te$_{75}$ thin film ; a characteristic relaxation time (.tau.$_{0}$ ), the spatial density of defect states (N), and the localized wavefunction (.alpha.$^{-1}$ ). It was formed that the threshold voltage depends on thickness, electrode distance, annealing time and temperature, respectively. The threshold voltage is increased as the thickness and the electrode distance is increased, while the threshold voltage is decreased in proportion to the increased annealing time and temperature.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.194-201
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• 2015

A frequency modulated ultra-wideband (FM-UWB) transmitter with a high-robust relaxation oscillator for subcarrier generation and a dual-path Ring VCO for RF FM is proposed, featuring low power and low complexity. A prototype 3.65-4.25 GHz FM-UWB transceiver employing the presented transmitter is fabricated in $0.18{\mu}m$ CMOS for short-range wireless data transmission. Experimental results show a bit error rate (BER) of $10^{-6}$ at a data rate of 12.5 kb/s with a communication distance of 60 cm is achieved and the power dissipation of 4.3 mW for the proposed transmitter is observed from a 1.8 V supply.

• Macromolecular Research
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• v.14 no.6
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• pp.617-623
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• 2006

In order to achieve an oriental lacquer (OL) film with a thick consistency, UV-curable silicone acrylate (SA) was added to OL by a dual curing process. The addition of 5 wt% UV-curable SA to the OL fomulation enabled the preparation via a single drying step of a $77{\mu}m-thick$ film exhibiting excellent surface properties. FTIR-ATR was used to investigate the effect of UV-curable SA on the behavior of film formation during curing, and the relaxation behavior of the produced films was investigated by dielectric spectroscopy. Dielectric properties were measured in the frequency range $10^{-2}-10^5\;Hz$ at various temperatures between -100 and $200^{\circ}C$. The results demonstrated that OL modified by UV-curable SA has a higher glass transition temperature and stronger secondary relaxation at a lower temperature than the conventional OL system. The OL film modified with UV-curable SA was presumed to be harder at the surface and tougher than conventional OL film.

• Journal of the Korean Society of Safety
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• v.9 no.4
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• pp.58-68
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• 1994

A miniature size electrostatic induction motor has been fabricated and studied parameters Influencing dominantly to the motor speed, such as a voltage and frequency of the 3 phase ac power source supplied to the stator of fabricated motor, the surface resistivity and relative dielectric constant of the rotor surface materials and the concurrently calculated relaxation time constants. It is found that the higher resitivity and/or the higher relative dielectric constant, concurrently the longer relaxation time constant of the rotor surface materials make the motor speed get higher speed. In case of discrete coated rotor surface it is found that the motor speed was increased logarithmically as narrow as width of the discrete coated Ti. And the degree of width of discrete coated Ti to the axial direction of the rotor was 60$^{\circ}$ and 150$^{\circ}$, the motor has got a 125% higher than that at the degree of 0$^{\circ}$.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.181-186
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• 2005

We demonstrate that the finite rate of dielectric relaxation in liquid crystals which has been ignored previously causes profound effects in the fast dielectric reorientation of the director. The phenomenon is relevant for submillisecond switching of the director when the switching rate approaches the rate of dielectric relaxation through the reorientation of the molecular dipoles. A submillisecond switching ($15-400\;{\mu}s$ for an optical retardation shift $0.3-2.2\;{\mu}m$ in $10-15\;{\mu}m$ thick cells) is demonstrated for dual frequency nematic cells with high pretilt that maximizes the dielectric torque acting on the director. We propose the theory of dielectric response in which the electric displacement depends not only on the present (as in the standard theory) but also on the past values of electric field and director. We design an experiment in which the standard "instantaneous" model and our model predict effects of opposite signs; the experimental data support the latter model.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.26-26
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• 2003

The backbone dynamics of ketosteroid isomerase, a homodimeric enzyme with 125 amino acid residues per subunit, has been studied in the presence/absence of a steroid ligand and 5％ trifluoroethanol (TFE) by $^{15}$ M relaxation measurements. The relaxation data were analyzed using the model-free formalism to extract the model-free parameters (S$^2$, $\tau$$_{e}$, and R$_{ex}$ ). The results show that a large number of the residues, particularly those involved in the dimer interaction, exhibit reduced order parameters (S$^2$) in the steroid-bound enzyme, indicating the increased high-frequency (pico- to nanosecond) motions in the interface region upon ligand binding. The results also show that that the presence of 5 ％ TFE in free enzyme causes little change or slight increase in the order parameters for a number of residues in the dimer interface region. However, the majority of the residues in free enzyme exhibit reduced order parameters in the presence of 5 ％ TFE, indicating that the increase in entropy is partially responsible for the increased stability of KSI by 5％ TFE.E.E.