• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.1
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• pp.59-64
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• 2004

We have fabricated the polymer dispersed liquid crystal (PDLC) cell where a control of phase separation is very important. The factors to influence the phase separation are mixing ratio of LC and polymer, curing temperature and UV intensity. In this paper, we inspected the change of a phase separation as a function of curing temperature for the mixture of E7 and. NOA65 with different ratios. When the LC concentration is less than polymer such as LC:NOA65 = 40:60wt％, the PDLC cell is influenced strongly by the curing temperature. However, when the LC concentration is much less than polymer such as LC:NOA65 = 80:20wt％, it is influenced slightly by the curing temperature. The reason is because the mixture shows upper critical solution temperature behavior and therefore it is important to know the behavior of phase separation as a function of curing temperature of the mixture.

• Journal of the Korean Ceramic Society
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• v.30 no.3
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• pp.229-235
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• 1993

Thermal history and thermal stress of alumina specimen, which occured from thermal shock process, were calculated by finite difference method. Stress intensity factor and crack growth in cyclic thermal fatigue were calculated from single thermal shock temperature history and thermal stress. Cyclic thermal life were estimated by bending strength after cyclic thermal shock under critical thermal shock temperature. Calculated stress intensity factor was compared with real experimental thermal fatigue life of specimen. Fatigue life until critical stress intensity factor and real experimental result were comparable.

• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.67-67
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• 2007

• Journal of the Korean Chemical Society
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• v.13 no.1
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• pp.1-4
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• 1969

Temperature effect on the critical micelle concentration of hexadecyl trimetyl ammonium bromide over the range of $2^{\circ}-50^{\circ}C$ has been investigated by the method of electrical conductivity. The values obtained have been formulated as a power series in T. Several thermodynamic parameters have been calculated for the temparature range examined and their values have been discussed in the light of current theories on the participation of solvent in micelle formation.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.172-172
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• 2010

$MgB_2$ doped with $TiO_2$ was prepared by the in-situ solid state reaction to study the effects of $TiO_2$ dopant on the flux pinning behavior of $MgB_2$ superconductor. From the field-cooled and the zero-field-cooled temperature dependences of magnetization, the realms of vortex-glass and vortex-liquid states of $TiO_2$-doped $MgB_2$ were determined in the H-T diagram (the temperature dependence of upper critical magnetic field and irreversibility line). The critical current density was estimated from the width of hysteresis loops in the framework of Beam's model at different temperatures. The results indicate that nano-scale $TiO_2$ inclusions play a role of the effective pinning centers and lead to the enhanced upper critical field and critical current density. It is suggested that the grain-boundary pinning mechanism is realized in $TiO_2$-doped $MgB_2$ superconductor.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.23-28
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• 2018

We derive a gap of specific heat discontinuity of superconducting crystals theoretically at the critical temperature $T_{CH}$ as an explicit function of applied magnetic field H by using the thermodynamic relations for Gibbs free energy and the linear model for the critical magnetic field $H_{CT}$. The derived a gap of specific heat discontinuity is compared with experimental results by J. Kacmarcik et al. for superconducting MgCNi3 crystal. Our specific heat gap function well explain the jump up phenomena of the superconducting crystals.

• Fire Science and Engineering
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• v.20 no.4 s.64
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• pp.91-97
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• 2006

This study was executed to review feasibility on the calculation of critical velocity with a reduced model of an actual tunnel in order to establish the optimum fire protection system for a fire in road tunnels. In a scaled model about 1/29 of an actual tunnel based on the Froude scaling, critical velocity was calculated by visualizing smoke flow and analyzing correlation with temperature. In the experiment, critical velocities at which smoke backflow length became zero showed a small difference within about 5% compared to results calculated by the Kennedy formula, and the relation between smoke flow and temperature distribution appeared similarly without getting greatly influenced by changes in fire intensity.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.4
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• pp.414-420
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• 1985

The melting phenomenal of the horizontal cylindrical ice-bar submerged in water are experimentally investigated for the temperature range from 2.5.deg. C to 15.deg. C. The shapes of the melting ice-bar are recorded by the Photo-elasticity Apparatus with modification of the test section. The shadowgraphs of the melting ice-bar show that water adjacent to the bar flows upward for the temperature range from 2.5.deg. C to 5.6.deg. C while above the temperature of 5.6.deg. C the flow is downward direction. The local and average Nusselt numbers become minimum at 5.6.deg. C which is considered as a critical temperature and the Nusselt numbers increase as temperature difference from the critical temperature increase.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.2
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• pp.223-231
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• 2001

In order to provide some insights into the influence of electric field, gas composition, and gas temperature on electron energy distribution and electron transport characteristics, the Boltzmann equation was solved by using cross section data for electron collisions, Critical electric fields for the corona development in dry air and flue gas are 150 and 80 Td, respectively. It was seen that the decrease of critical electric field in flue gas is mainly caused by the $H_2O$ addition through the comparison of ionization and attachment coefficients of gas components. Increase of $O_2$, $H_2O$, and $CO_2$ contents in gas affected discharge characteristics according to their reciprocal characteristics between lowering the ionization threshold and increasing the electro-negativity. As electric field increases, electrons with higher energies in the electron energy distribution also increase. The mean and characteristic electron energies also linearly increase with electric field. The variation of flue gas temperature did rarely affect on the electron energy distribution function and electron transport characteristics, because the gas temperature is several hundreds or thousands times lower than the electron temperature.

• Journal of the Korean Home Economics Association
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• v.23 no.4
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• pp.61-68
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• 1985

This study was conducted in a Korean airline catering operation where about 8, 000~10, 000 in flight meals per day were served. Time ad temperature observations were made in an actual airline catering operation to determine critical control points in mushroom and cheese omelet production, and to provide guidelines for the effective quality control programs of the airline catering operation. All data collection was replicated three times. Time and temperature data were collected by using standard instruments throughout the process sequence. Most phases of the food prodct flow were identified as critical control points. Holding phases of after cooking, and before and after reheating need a special attention, since foods were held at room temperature. Several guidelines were suggested for the effective quality control programs for the airline catering operation.