• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.5
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• pp.79-85
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• 2004

This study was performed to evalute mechanical and drying shrinkage properties of polypropylene fiber reinforced high flow concrete. The compressive strength and drying shrinkage ratio were increased with increasing the binder volume ratio and decreased with increasing the content of polypropylene fiber. The splitting tensile strength was increased with increasing the binder volume ratio and the content of polypropylene fiber. The flexural strength was increased with increasing the binder volume ratio and increased by the polypropylene fiber content 0.4%, but above the polypropylene fiber content 0.6% was decreased. This concrete can be used for high flow concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.153-158
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• 2001

The effects of polymer-cement ratio and shrinkage-reducing agent content on the durability characteristics of ultrarapid-hardening polymer-modified mortars using redispersible polymer powder are examined. As a result, the flexural and tensile strengths of the ultrarapid-hardening polymer-modified mortars using redispersible polymer powder tend to increase with increasing polymer-cement ratio, and tend to decrease with increasing shrinkage-reducing agent content. However, the compressive strength of the ultrarapid-hardening polymer-modified mortars using redispersible polymer powder decrease with increasing polymer-cement ratio and shrinkage-reducing agent content. And, water absorption and mass change of chemicals resistance of ultrarapid-hardening polymer-modified mortars using redispersible polymer powder tend to decrease with increasing polymer-cement ratio.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.394-397
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• 2005

In korea, the power consumption is increasing every year because of economic growth, requiring of convenience and delightfulness condition. As increasing power consumption, Private Use is steadily increasing and the rate of electrical accident is increasing. Therefore we research the electrical safety culture of our people by the survey of electrical safety. The subject to investigation is possessor, occupier of Private Use and electrical safety manager. This paper will be used to base data for the protection of electrical accident and facility accident at Private Use

• Membrane and Water Treatment
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• v.4 no.3
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• pp.191-202
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• 2013

The application of ultrafiltration operation to the dialysis in countercurrently parallel-flow rectangular membrane modules was investigated. The assumption of uniform ultrafiltration flux was made for operation with slight concentration polarization and declination of transmembrane pressure. Considerable improvement in mass transfer is achievable if the operation of ultrafiltration is applied, especially for the system with low mass transfer coefficient. The enhancement in separation efficiency is significantly increased with increasing ultrafiltration flux, as well as with increasing the volumetric flow rates. Furthermore, increasing the volumetric flow rate in retentate phase is more beneficial to mass transfer than increasing in dialysate phase.

• Journal of Korea Technology Innovation Society
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• v.2 no.2
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• pp.309-325
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• 1999

If we want to overcome the current IMF-guarded economic situations as early as possible and to change the present industry structure to the new knowledge-based structure, it is a great necessity to increase the capability of technology innovation as a key factor of the international competitiveness, and to establish the infrastructure of venture business for increasing utilization of technologly and patent. Even though there has been a great increase in application and enrollment of the Industrial Property Rights (i.e. IPRs) including patent recently, the number of unused IPRs are increasing progressively every year (for example, the ratio of unused patent is about 60% in 1997), and illegal use of patent and dependance on the foreign patent are increasing sharply. This paper will suggest policy on nurturing venture business for increasing utilization of the unused IPRs, including technology transaction strategy and link strategy of the high-tech industries between metro Taejon and Chungcheong Area.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.2
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• pp.59-66
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• 2006

This study is performed to evaluate freezing and thawing properties of polypropylene fiber reinforced eco-concrete using soil, natural coarse aggregate, soil compound and polypropylene fiber. The mass loss ratio is decreased with increasing the content of natural coarse aggregate and soil compound, but it is increased with increasing the content of polypropylene fiber. The ultrasonic pulse velocity, dynamic modulus of elasticity and durability factor are increased with increasing the content of natural coarse aggregate and soil compound, but it is decreased with increasing the content of polypropylene fiber. The mass loss ratio, ultrasonic pulse velocity, dynamic modulus of elasticity and durability factor are $1.49{\sim}3.32%,\;1,870{\sim}2,465\;m/s,\;77X10^2{\sim}225X10^2\;MPa\;and\;84.6{\sim}92.8$ after freezing and thawing 300 cycles, respectively. These eco-concrete can be used for environment-friendly side walk and farm road.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.4
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• pp.440-447
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• 1999

The frosting characteristics on the vertical parallel plates with three cooling plates were experimentally investigated. The experimental parameters were the cooling plate temperature, the air humidity, the air temperature, the air Reynolds number, and the location. The frosting conditions were limited to air temperatures from 10 to $15^{\circ}C$ , air Reynolds numbers from 1600 to 2270, air humidity ratios from 0.00275 to 0.0037kgw/kga and cooling plate temperatures from -10 to $-20^{\circ}C$. Frost growth and density toward the front of the plate were more thick and dense than toward the rear. Frost growth increased with decreasing plate temperature and increasing humidity. In the conditions of the laminar flow, dew point below $0^{\circ}C$and non-cyclic frosting period, frost thickness increased with increasing air temperature. The reason of increasing frost thickness with increasing air temperature was sublimation-ablimation process. The average growth thickness along the locations showed little dependence on the Reynolds numbers.

• Journal of the Korean Wood Science and Technology
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• v.14 no.2
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• pp.13-20
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• 1986

The effect of heat treatment on the dynamic viscoelasticity of the woods of Picea sitchensis and Paulownia coreana which have been for musical instruments was investigated. The treatment was made in a temperature range of 60-180$^{\circ}C$ for periods of 3 hours to 24 hours. The results obtained are summarized as follows: Moisture absorption decreased with increasing temperature. Dynamic Young's modulus decreased with increasing temperature and hours. Dynamic viscoelasticity decreased with increasing moisture content, but internal friction increased with increasing amount of moisture content.

• Journal of the Korean Vacuum Society
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• v.8 no.4A
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• pp.450-455
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• 1999

We present Photoluminescence (PL) and Atomic Force Microscopy (AFM) image on InAs quantum dots (QDs) having different size which grown by Molecualr Beam Epitaxy (MBE). For different size QDs, analysis of the AFM profiles show that the density of QDs was the maximum value $(1.1\times10^{11}\textrm{/cm}^2)$ at 2.0 ML. In the spectra of QDs, it is found that the peak energy decreases with increasing dot size due to the effect of quantum confinement. Temperature dependence of PL intensities show that the PL is quenching and Red shift as the temperature increase. The FWHM range of 20K~180K is narrowing with increasing temperature. When temperature is over 180K, the line-width starts to in creases with increasing temperature. At last, temperature dependence of the integrated intensities were fit using the Arrehenius-type function for the activation energy. Fit value of the activation energy was increased with increasing QDs-size.

• Journal of Magnetics
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• v.13 no.1
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• pp.11-18
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• 2008

This study examines a new macroscopic ferrimagnet, Co-TbN. This ferrimagnet, consisting of two metallic phases, Co and TbN, demonstrated the typical macroscopic ferrimagnet properties of a magnetic compensation point and a negative giant magnetoresistance (GMR). The Co-TbN system with 32% TbN composition showed 0.72% GMR in magnetic fields up to 8 kOe at room temperature and 9% GMR in 40 kOe at 250 K. In the Co-TbN system, GMR exhibited a different dependence on temperature from that of ordinary GMR materials whose negative magnetoresistance decreases with increasing temperature. In contrast to ordinary GMR materials whose negative magnetoresistance decreases with increasing temperature, the GMR effect in the Co-TbN system increased with increasing temperature, due to the increase of ferromagnetic alignment of the Co and TbN in the magnetic field caused by the decreased exchange coupling with increasing temperature.