• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.725-728
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• 2001

We have fabricated thin films using the DC/RF magnetron sputtering of 74wt%Ni-l8wt%Cr-4wt%Al-4wt%Cu alloy target and studied the effect of the process parameters on the electrical properties for low TCR(Temperature Coefficient of Resistance) films. In sputtering process, pressure, power and substrate temperature, are varied as controllable parameter. The films are annealed to 400$^{\circ}C$ in air and nitrogen atmosphere. The sheet resistance, TCR of the films increases with increasing annealing temperature. It abruptly increased as annealing temperature increased over 300$^{\circ}C$ in air atmosphere. From XRD, it is found that these results are due to the existence of NiO on film surface formed by annealing. As a results of them, TCR can be controlled by variation of sputter process parameter and annealing of thin film.

• Journal of the Korean Ceramic Society
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• v.23 no.1
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• pp.67-73
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• 1986

SiC and $SiC-Si_3N_4$ powder were synthesized via the carbiding and carbiding-nitriding reaction of Jecheon quartz respectively using graphite as a reducing agent. $\beta$-SiC+($\alpha$+$\beta$)-$Si_3N_4$ composite was obtained by the carbiding-nitriding reaction of Jecheon quartz-graphite mixture at 1, 35$0^{\circ}C$ in $H_2$ atmosphere. $\beta$-SiC+($\alpha$+$\beta$)-$Si_3N_4$ composite was obtained by the carbidint-nitriding reaction of Jecheon quartz-graphite mixture at 1, 35$0^{\circ}C$ in $N_2-H_2$ atmosphere. The ratio of $\beta$-SiC+($\alpha$+$\beta$)-$Si_3N_4$ content in a produced composite could be controlled by adjusting the reaction time and gaseous mixture.

• Journal of the Korean institute of surface engineering
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• v.25 no.6
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• pp.293-298
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• 1992

Various vanadium-oxide thin films were deposited by e-beam and thermal evaporation of V2O5, V2O3, and VO2 powders. Films with thickness of $2000\AA$ were subjected to annealing at $300^{\circ}C$~$450^{\circ}C$ in N2 atmosphere for the crystallization and desification purposes. For the films deposited from V2O5 and VO2 sources, sources, Magneli (VnO2n-1$ 4\leq$ $n\leq$ 8) and VO2 phase appeared at $300^{\circ}C$, respectively, but VO2 phase also transformed into Magneli phase at $450^{\circ}C$ by severe reduction. On the contrary, VO2/VO mixed phases resulted from congruent evaporation of V2O3 unchanged after the same annealing treatment due to the balanced reduction and oxidation of VO2 and VO whcih have different equilibrium O2 pressures. It is suggested that the annealing in the controlled oxidation atmosphere or the deposition using mixed oxide sources are necessary to get the film containing VO2 phase.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1041-1042
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• 2006

High heat-resistant Al-Fe-V-Si and Al-Fe-V-Si-X rapidly solidified powder metallurgy (RS P/M) alloys have been developed under well-controlled high purity argon gas atmosphere. The $Al_{90.49}Fe_{6.45}V_{0.68}Si_{2.38}$ (at. %) RS P/M alloy exhibited high elevated-temperature strength exceeding 300 MPa and good ductility with elongation of 6 % at 573 K. Reduction of $H_2O$ partical pressure in P/M processing atmosphere led to improvement in mechanical properties of the powder-consolidated alloys under elevated-temperature service conditions. Ti addition to the Al-Fe-V-Si conduced to enhancement of the strength at room temperature. The tensile yeild strength and ultimate strenght were 545 MPa and 722 MPa, respectively.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1091-1092
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• 2006

Silicon nitride - silicon carbide composite was developed by using an abrasive SiC powders as a raw material. The composites were prepared by mixing abrasive SiC powder with silicon, pressing and sintering at $1400^{\circ}C$ under nitrogen atmosphere in atmosphere controlled vacuum furnace. The proportion of silicon in the initial mixtures varied from 20 to 50 wt%. After sintering, crystalline phases and microstructure were characterized. All composites consisted of ${\alpha}-Si_3N_4$ and ${\beta}-Si_3N_4$ as the bonding phases in SiC matrix. Their physical and mechanical properties were also determined. It was found that the density of the obtained composites increased with an increase in the $Si_3N_4$ content formed in the reaction.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.60-71
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• 1999

The micrometeorological tower flux network is the cornerstone of the global terrestrial vegetation monitoring. The eddy covariance technique used for tower fluxes is derived from the conservation of mass and is most applicable for steady-state conditions over flat, extended, and uniform vegetation. This technique allows us to obtain surface fluxes of energy budget components, greenhouse and trace gases, and other pollutants. The quality-controlled flux data are invaluable to validate various models with temporal scales ranging from minutes to years and spatial scales ranging from a few meters to hundreds of kilometers. In this paper, we review the theoretical background of this important eddy covariance technique, examine the measurement criteria and corrections, and finally suggest some measurement strategies that may facilitate coordinated flux measurements among different disciplines and provide a strong infrastructure for the global flux network.

• Journal of the Korean institute of surface engineering
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• v.22 no.3
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• pp.118-127
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• 1989

The rate of electrodeposition Zinc-nickel alloy on to electrolytic ione in sulface solution both under an inter and air atmospherss has studied by use of a rotating disc geometry. The kinetics shows 1st order reaction, and the rate constants are proportional to the square root of rpm, however, they are less than the valuse suggested by Levich. The rate constants of zinc deposition approach the total mass transfer rate constants with increasing potential and deviate with increasing rotaing speed, but those of nickel deposition are constant. Below $40^{\circ}C$ the activation engrgies of zinc deposition and nikel deposition were 4.4Kcal/mol and 6.3Kcal/mol respectively. There results show that overall reaction rate of zinc-nickel plaeting is controlled by mixed reaction and zinc deposotion is more affected by mass transfer reaction than nickel. The current density for the zinc-nickel plating was less in an air atmosphere than in a nitrogen atmosphere. The cathode efficiency increased with decreasing cathode rotating speeds, potentials, and increasing temperatures. Zzinc-nickel platings are more improved in microhardnss than zinc platings.

• Korean journal of applied entomology
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• v.51 no.2
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• pp.131-140
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• 2012

The hawthorn spider mite, Tetranychus viennensis, is a pest of apples and a quarantine pest from some countries that import apples from Korea. A controlled atmosphere and temperature treatment system (CATTS) was developed as an alternative disinfestation method to methyl bromide fumigation treatment, and has been applied to control various insects and other arthropod pests on fruits. We applied CATTS to disinfect T. viennensis under conditions that were previously developed to control the peach fruit moth, Carposina sasakii. First, T. viennensis was sampled from Japanese apricot, Prunus mume, and identified by its morphological characters. In addition, both cytochrome oxidase I (COI) and internal transcribed spacer (ITS) sequences supported the morphological identification. Second, the heat-tolerant developmental stage was determined in T. viennensis. When a $46^{\circ}C$ heat treatment was applied to egg, nymph, and adult stages of T. viennensis, adults were the most tolerant stage. Third, when heat temperature was used along with 1% $O_2$ and 15% $CO_2$, the mites showed a significant increase in susceptibility to the heat treatment. Finally, CATTS at $46^{\circ}C$ with 15% $CO_2$ and 1% $O_2$ for 30 min resulted in 100% mortality of all T. viennensis development stages. These results indicated that CATTS isapplicable to disinfest T. viennensis in post-harvest apples.

• Applied Biological Chemistry
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• v.34 no.1
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• pp.14-20
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• 1991

Changes in fruit quality and some components of Unshiu orange(Citrus Unshiu Marc. Hayashi) stored at $2^{\circ}C$ in air or a controlled atmosphere(CA, $O_2$ 10%, $CO_2$ 2%) for 111 days were studied. The incidence of rot fruits was higher in air(12.7%) than in CA condition(3.9%). The appearance of the fruits was better in CA condition than in air. There was no significant difference in the weight loss of whole fruits between both storage conditions. The ratio of the flesh weight In whole fruits under CA condition was slightly lower than those in air until 62 days of storage, while it showed no rapid decrease in the later period of storage. Under both storage conditions, the Brix in the flesh increased in the early Period of storage and then decreased slowly, while the free acid contents decreased gradually during storage. In comparison with the fruits stored in air, those under CA condition showed lower total sugar content. The sugar in the flesh of the fruits is composed of sucrose, fructose and glucose. The content of total sugar as well as each sugar showed no distinct difference under both storage conditions. In the flesh of the fruits, citric acid comprised about 90% of the organic acid and malic acid the second abundant acid. During storage, the contents of citric, malic and oxalic acid decreased. Significant difference in the decreasing rate of total organic acid between both stnrage conditions was not found. From the above results, it might be considered that CA could be applied lot the storage of Unshiu orange grown on Cheju

• Journal of the Korean Ceramic Society
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• v.19 no.3
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• pp.193-198
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• 1982

The vaporization of $MgFe_2O_4$ was studied in $H_2-CO_2$ atmosphere over the temperature range of 600 to 90$0^{\circ}C$ by means of the transpiration method. It was found that the rate of vaporization for $MgFe_2O_4$ is controlled by a first order phase-boundary chemical reaction. The obtained activation energy of vaporization is 17.1 Kcal/mol.