• Macromolecular Research
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• v.13 no.2
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• pp.96-101
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• 2005

Thin-film humidity sensors were prepared using inorganic/organic hybrid polyelectrolytes, which were prepared from the sol-gel reaction of copolymers of [2-(methacryloyloxy)ethyl]dimethylpropylammonium bromide (MEPAB), n-butyl methacrylate (BMA), and 3-(trimethoxysilyl)propyl methacrylate (TSPM) with tetraethyl ortho-silicate (TEOS). The humidity-sensitive polyelectrolytes were composed of the copolymers having the following mole ratios of MEPAB, BMA, and TSPM: 60/30/10, 55/30/15, and 50/30/20. We found that the impedance varied with the content of MEPAB or TEOS; it ranged from $10^{7} to 10^{3}\Omega$ between 20 and $95\%$ relative humidity, which is the range required for a humidity sensor operating at ambient humidity. In addition we investigated a number of characteristics of these humidity sensors, such as their hysteresis, response time, temperature dependence, frequency dependence, water durability, and long-term stability.

• Journal of the Optical Society of Korea
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• v.15 no.3
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• pp.237-243
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• 2011

Thermal characteristics, such as diffusivity and temperature induced change in the fiber mode index of rotation sensing fiber coil are critical factors which determine the time varying, thermo-optically induced bias drift of interferometric fiber-optic gyroscopes (IFOGs). In this study, temperature dependence of the transient effect is analyzed in terms of the thermal characteristics of the fiber coil at three different temperatures. By applying an analytic model to the measured bias in the experiments, comprehensive thermal factors of the fiber coil could be extracted effectively. The validity of the model was confirmed by the fact that the extracted values are reasonable results in comparison with well known properties of the materials of the fiber coil. Temperature induced changes in the critical factors were confirmed to be essential in compensating the transient effect over a wide temperature range.

• Journal of the Optical Society of Korea
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• v.12 no.1
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• pp.57-61
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• 2008

We investigated the laser pulse-width dependence of dense plasmas confined within the magnetic length of $In_{0.2}Ga_{0.8}As$/GaAs multiple quantum wells under high magnetic fields up to 31 T. To fully fill the Landau levels of effectively zero-dimensional system, we used intense femtosecond (fs) laser pulses to create carrier densities near $10^{13}/cm^2$. The observed photoluminescence showed a characteristic of superfluorescence, above critical magnetic field when being excited by pulses shorter than coherence buildup time.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.11
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• pp.1335-1341
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• 1988

A pH-ISEFET microprobe for in vivo measurements has been fabricated by combining ISFET (SL-IIS) chip and capillary thin film reference electrode. A two-step TCE oxidation for the gate oxide layer and multilayer encapsulation using silicone rubber and epoxy were specially used for the improvement of the stability and temperature dependence of the ISFET's. The measured sensitivit, response time and temperature dependence of the pH-ISFET microprobes are 50 mV/pH, less than one second, and - 0.01 pH/$^{\circ}$ , respectively. By operating continuously more than 40 days, a long term stability of 0.016 pH/day is obtained. The result of pH monitoring of femoral arterial blood in a rabbit is fairly good agreement with the value of blood gas analysis.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.10
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• pp.1-10
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• 1994

In most application programs, loops usually contain most of the computation in a program and are the most improtant source of parallelism. When loops are executed on multiprocessors, the cross iteration data dependences need to be enforced by synchronization between processors. In this paper, we propose a new synchronization scheme(Free/Hold) for reducing overgeads occured by synchronization variables in data oriented scheme and delay of time occured by synchronization instruction in statement oriented scheme. The Free/Hold mechanism enforces the correct execution order by inserting synchronization instruction between each instance with data dependence relationship using the RD(Real dependence Distance). We also present an algorithm for removing unnecessary dependences in one-to-many dependences.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.121-124
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• 2000

The time dependence of irreversible magnetization of grain aligned infinite layer superconductor Sr$_{0.9}$La$_{0.1}$CuO$_2$ was measured in temperature range of 2 K < T < 30 K for H= 0.5 T, 1.0 T and 1.5 T parallel to c-axis. From this, we calculated normalized flux creep rate S(T) ${\equiv}$ dlnM/dlnt and found that the temperature independent region in S(T) is significantly wide in comparision with other cuprate superconductors. Using the method of Maley et al., we also deduce the current density dependence of pinning potential and glassy exponent ${\mu}$.

• Journal of the Korean Society of Safety
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• v.26 no.2
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• pp.36-41
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• 2011

For the safe handling of n-hexane, the explosion limit at $25^{\circ}C$, the temperature dependence of the explosion limits and the lower flash point were investigated. And AITs(auto-ignition temperatures) by ignition delay time for n-hexane were experimented. By using the literatures data, the lower and upper explosion limits of n-hexane recommended 1.0 Vol% and 8.0 Vol%, respectively. In this study, the lower flash points of n-hexane recommended $-23^{\circ}C$. This study measured relationship between the AITs and the ignition delay times by using ASTM E659-78 apparatus for n-hexane, and the experimental AIT of n-hexane was $240^{\circ}C$. The new equations for predicting the temperature dependence of the explosion limits of n-hexane is proposed. The values calculated by the proposed equations were a good agreement with the literature data.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.15-18
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• 2003

HTS(High Temperature Superconductor) tapes have dependence on critical characteristics such as electric, magnetic field and temperature. In order to confirm these effects, we examined the current transport characteristics of HTS tapes. First, after being fed DC and AC, the dependence of HTS tapes of 10cm on external magnetic field was investigated. On centeral region of HTS tape, about 1cm, external magnetic field was applied. Second, after applying DC of 50A to HTS tapes, we applied time variable magnetic field about 100mT and investigated the quench characteristics. Finally, AC, which is about 10 times of I$_{c}$, was applied to HTS tapes and over current characteristics were investigated. The data acquired in this study will be used as a source for the study of HTS cable conductor which is supposed to carry on.n.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.279-286
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• 2000

Magnetic field dependence of magnetization reversal in Co/Pt multilayers has been quantitatively investigated. Serial samples of Co/Pt multilayers have been prepared by dc-magnetron sputtering under various Ar pressure. Magnetization reversal was monitored by magnetization viscosity measurement and direct domain observation using a magneto-optical microscope system, and the wall-motion speed and the nucleation rate R were determined using a domain reversal model based on time-resolved domain reversal patterns. Both and R were found to be exponentially dependent on the reversing applied field. From the exponential dependencies, the activation volumes of the wall motion and nucleation could be determined based on a thermally activated relaxation model, and the wall-motion activation volume was revealed to be slightly larger than the nucleation activation volume.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.453-459
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• 2013

In phtosynthetic light harvesting complexes, the electronic transition energies of chlorophylls are influenced by the Coulombic interaction with nearby molecules. Variation of the interactions caused by structural inhomogeneity in biological environment results in a distribution of disordered electronic transition energies of chlorophylls. In order to provide a practical guide to predict qualitative tendency of such distribution, we model four porphyrin derivatives including chlorophyll a molecule interacting with an external positive charge and calculate their transition energies using the time dependent density functional method. It is found that ${\pi}-{\pi}^*$ transition energies of the molecules are generally blue-shifted by the charge because this stabilizes occupied molecular orbitals to a greater extent than unoccupied ones. Furthermore, new transitions in the visible region emerge as a result of the red-shift in energy of an unoccupied Mg orbital and it is suggested that light-induced electron transfer may occur from the tetrapyrrole ring to the central magnesium when the molecules are interacting with a positive charge.