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Soil displacement from frost heave on forest road cut-slopes
이명교,이준우,최성민,김현숙 충남대학교 농업과학연구소 2018 Korean Journal of Agricultural Science Vol.45 No.2
The frost heave process from repeated freezing and thawing actions in winter on forest road cut-slopes is important for forest road maintenance and management. This study investigated the damages of the forest heave process on forest road cut-slopes by measuring the changes in the road-cut surface elevation and sediment production and by conducting vegetation surveys which were aimed at providing information for forest road maintenance plans. The temperature and humidity differences were determined between the north and south cutslopes. T-test showed that the north slope had a lower temperature and humidity than that of the south slope. Field observations also confirmed frozen soils on the north slopes, indicating that the north slopes are susceptible to frost heave. Sediment was converted to dry weight per unit area (g/m2). T-test showed that the north slope produced more sediment than that of the south slope. The study confirmed that more frost heave occurred on the north cut-slopes than on the south cut-slopes. Vegetation surveys were conducted on five cut-slope plots. Considering the dominant species found above the cut-slopes, vegetations in all the plots are expected to succeed to pine and oak in the future. The dominant species appearing on the cut-slopes of the study area were exotic species because the elapsed time of the site was only 2 - 4 years.
수열합성에 의한 $Pb(Mn_{1/3} Sb_{2/3})_{0.08} Ti_{0.495}Zr_{0.425}O_3$ 계의 분말제조 및 4K_P$ 특성
이명교,홍창희 한국세라믹학회 1986 한국세라믹학회지 Vol.23 No.3
Formation of powders and electromechanical coupling factor of $Pb(Mn_{1/3} Sb_{2/3})_{0.08} Ti_{0.495}Zr_{0.425}O_3$ by hydro-thermal synthesis are described. The hydrothermal reactions each were accomplished at 12$0^{\circ}C$~25$0^{\circ}C$ for 5hours and sintering was accomplished at 1, .20$0^{\circ}C$ for 1hours. The PZT powders by hydrothermal synthesis were formed above 16$0^{\circ}C$ and the forms were cubic types. The ratio of grain size of sintered sample to powder was slowly decreased with the rising of hydrothermal reactino temperature but decreased rapidly above 22$0^{\circ}C$ Sintering density was decreased with the rising of hydrothermal reaction temperature above 16$0^{\circ}C$ but dielectric constant was increased. Electromechanical coupling factor $K_P$ was almost constant at 16$0^{\circ}C$~24$0^{\circ}C$ range and the value of $K_P$ was about 0.43-0.45.
Carbon Black Graft Polymer의 電氣的 特性
李明敎 釜山工業大學校 1981 論文集 Vol.22 No.2
Carbon Black grafted with vinyl monomers or copolymers is called Carbon Black Graft Polymer (C.G) . This can be used as a raw material for stable thick film resistors and sheet heaters as well. Besides, by an appropriate method of preparation under proper conditions it gives resistors with large and stable positive temperature coefficient, which can applied for thermistors and heaters with self temperature control. In this paper, the effects of dimension and thermal conditions such as thermal conductivity, the extend of air convection, resistor-temperature characteristic, and ambient temperature on the voltage-current characteristic of the resistors are discussed.