• Journal of KSNVE
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• v.7 no.4
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• pp.621-629
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• 1997

For computer aided design and costruction of low noisy power plants, indoor and outdoor noise prediction program has been developed. The program utilizes the predefined data of noise sources and building materials and has the faculty to estimate the source level using the empirical formula in case of the measured data not being available. In the noise prediction, the mutual noise propagation between indoor and outdoor sites are considered. The outdoor noise source in the calculation of geometric divergence effects is modelled as the omni-directional finite line or planar source according to the source geometry and the receiving points. Outdoor noise prediction is carried out to consider the diffraction effect due to plant structures as well as the attenuation effect due to atmospheric absorption and soft ground. The results of indoor and outdoor noise prediction for a recently constructed diesel engine power plant show good agreement with the measured.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.142-142
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• 2003

The effects of film thickness on the dipolar relaxation of ferroelectric PbTiO$_3$ films were investigated in the microwave-frequency range. The dielectric constants ($\varepsilon$) and the dielectric losses (tan $\delta$) were successfully measured up to 30 ㎓ using interdigital capacitors. The PbTiO$_3$ thin films were deposited on the quartz substrate at room temperature and postannealed in oxygen atmosphere. As the film thickness increased, its grain size and tetragonality were enhanced. And the dipolar relaxation behavior began to appear in the thin films with approximately 20 nm thickness, since ferroelectric domains could not be formed hi small grains. The observed relaxation frequency (above 10 ㎓) was higher than the previous values reported in bulk ceramics. It can be correlated with the extremely small domain size of the thinfilms as shown by TEM. And, the Rayleigh constant [1] from domain wall motions was alsoinvestigated by LCR meter at 100 KHz.

• Journal of Environmental Health Sciences
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• v.4 no.1
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• pp.23-25
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• 1977

Transaminase has been a popular methods in the clinical laboratory for the diagnosis of particular diseases. The methods we are familiar with should be considered further on the serum states provided on the test to be done. (serum freshness, temperature and duration preserved) I have studied transaminase activities of the serum preserved under frozen (-10$\circ$C), refrigerated (4$\circ$C) and room temperature conditions. At a given interval those activities of serum are measured and then the results are compared with the optical density and calculated for the standard deviation and percent variation (Table 1. & Fig. 1.) G.O.T. activity is maintained decreased at a relatively constant rate from 2nd day to 14th day preservation under frozen and refrigerated but its activity variation at 25$\circ$C are far greater than the above conditions throughout the test periods. Elevated G.P.T. level of serum compared with G.O.T. are remained at any temperature and duration. Unless the determination of amino acid level study can not ruled out clearly.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1334_1335
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• 2009

In this paper we have presented recent studies concerning the high performance oxide thin film transistor (TFT) with a-IGZO channel and $ZrO_2$ gate dielectrics. The a-IGZO TFT is fully fabricated at room-temperature without any thermal treatments. The $ZrO_2$ is one of the most promising high-k materials with high capacitance originated from the high dielectric constant. The a-IGZO TFT with $ZrO_2$ shows high performance exhibiting high field effect mobility of $39.82\;cm^2$/Vs and high on-current of 2.52 mA at 10V.

• Journal of Powder Materials
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• v.13 no.4 s.57
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• pp.278-284
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• 2006

Spherical Ag powder was prepared in the system of $AgNO_3\;and\;NaBH_4$ by wet chemical reduction method. The size of Ag powder was increased as the reaction temperature and the concentration of reducing agent was decreased in the constant concentration of dispersion agent. Optimum conditions of producing Ag powder having $1.39{\mu}m$ of D50 was 1M of $AgNO_3$, 0.5M of $NaBH_4$, 1.5g of Gelatine in the room temperature.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.1
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• pp.83-91
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• 2012

In this study, the compressive strength characteristics of lime-cement-soil mixtures, composed of lime, soil, and a small amount of cement, were investigated by performing the unconfined compression tests, the freezing and thawing tests, the wetting and drying tests and the permeability tests. The specimens were made by mixing soils with cement and lime. The cement contents were 0, 6, 8 and 10 %, and the lime contents were 2, 4, 5, 10, 15 and 20 % in weight. Each specimen was cured at constant temperature in a humidity room for 3, 7 and 28 days. The compressive strength characteristics of the lime-cement-soil mixtures were then investigated using the unconfined compression tests, freezing and thawing tests and the wetting and drying tests. Based on the test results, a discussion was made on the applicability of the lime-cement-soil mixtures as a construction material.

• Journal of the Korean Magnetic Resonance Society
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• v.3 no.2
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• pp.84-89
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• 1999

The 87Rb quadrupole coupling constants (e2qQ/h) and the asymmetry parameters (η) in RbMnCl3 were determined from a nonlinear least-squares fit to the 87Rb NMR powder spectra. The spectra were acquired in the temperature range from 260K to 330K. An important feature in this work is the determination of the quadrupole coupling constants and the asymmetry parameters for two physically nonequivalent Rb sites, Rb(I) and Rb(II), as a function of temperature. In addition, a structural phase transition at room temperature was conformed with the changes in the quadrupole coupling constant and the asymmetry parameter of Rb(II) site.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.749-751
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• 2002

$(Pb_{1-x}Sr_x)TiO_3$ $(0.6{\leq}x{\leq}0.8)$ thin films were prepared by the MOD method for tunable microwave device application and their characteristics were investigated as a function of Sr content(x) and applied field. Thin films showed a homogeneous microstructure and the tetragonality(c/a) was slightly decreased with increasing Sr content. With increasing Sr content, Curie temperature of the thin films showed a decreasing tendency. For the PST thin films, the dielectric constant at room temperature, Tc, and $tan{\delta}$ were 750~1900, $-70^{\circ}{\sim}-30^{\circ}C$ and 0.025~0.04, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.3
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• pp.240-246
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• 2002

Bypass air conditioning systems are divided into three types; an outdoor air bypass, a mixed air bypass and a return air bypass system. What makes the return air by pass system more effective is that it directs all of moist outdoor air through the cooling coil. The bypass air conditioning system can maintain indoor R.H (Relative Humidity) less than a conventional CAV (Constant Air Volume) air conditioning system by adjusting face and bypass dampers at part load. When a design sensible load (the ratio of sensible load to total sensible load) is 70 percent (at this time, RSHF (Room Sensible Heat Factor) . 0.7), indoor R.H was maintained 59 percent by the return air bypass system, but 65 percent by the conventional CAV air conditioning system (valve control system). The bypass air conditioning system can also improve IAQ (Indoor Air Quality) in many buildings where the number of air change is high.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.23-24
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• 2006

Magnetic and magneto-optical properties of regioregular (>99%) poly(3-dodecylthiopenes are investigated. Faraday rotation of spin-coated films show extremely large Verdet constants, falling strongly with decreasing regioregularity. EPR spectroscopy at room temperature shows the presence of about 1 spin/190 monomers, indicative of delocalisation beyond a single polymer chain. SQUID measurements on the polymer give an effective magnetic moment of about 48900 mB, corrsponding to a S-value of 25.000. The Weiss-constant is 1.33 K indicating ferromagnetic coupling. Our experimental results show that organic polymer magnets can be prepared. Large MO effects allow the use of these materials in all-organic MO-sensors and devices.