• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.722-728
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• 1997

This study was investigated to find storage material of thermal energy storage system for a vehicle with the basic material of $Ba(OH)_2{\cdot}8H_2O$ and to test a feasibility of it. Experiment was investigated usability for long time and state change and thermal property after cycle with $Ba(OH)_2{\cdot}8H_2O$ and misxture doping additive to it. The result of this research indicated the mixture adding $Sr(OH)_2{\cdot}8H_2O$ to $Ba(OH)_2{\cdot}8H_2O$ have high feasibility as storage material for thermal energy storage system. This mixture did not exhibit the state change during 1300 cycles and the rate of decrease of heat realese energy was about 2%, relatively low value.

• Korean journal of applied entomology
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• v.22 no.2 s.55
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• pp.147-159
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• 1983

In general, herbicides have been classified according to selectivity, mobility. time of application, methods of application, mode of action and chemical property and structure. However, there was no generally accepted classification system for practical use in the field. The primary processes affected by the majority of herbicides are the growth process through cell elongation and/or cell division, the photosynthetic process specifically the light reaction, the oxidative phosphorylation and the integrity of the membrane systems. The usual approach in the study of the mechanism by which herbicides kill or inhibit the growth of plants is to initially determine the morphological phototoxicity systems, The mechanism by which a herbicide kills a plant or suppresses its development is actually the resultant effect of primary and secondary(or side) effects. In most instances, the death of the plant is due to the secondary effects. To induce the desired response, a herbicide must be able to gain entry into the plants and once inside, to be transported within the plant to its site(s) of activity in concentrations great enough. Obstacles to the entry and movement of herbicides in plants are generally classified by leaf and soil obstacles, translocation obstacles and biochemical obstacles, and these obstacles are also strongly influenced by plant species and by environmental factors such as light, temperature, rainfall and relative humidity. And hence, in most instances, results obtained from laboratory or greenhous vary from those of field experiment. Author attempted to classify herbicides from the field experiment using the two-dimensional ordination analysis to obtain practical information for selecting effective herbicides or to choose effective herbicide combinations for increasing herbicidal efficacy or reducing the chemical cost. Based on this two-dimensional diagram, desired herbicides or combinations were selected and further investigated for the interaction effects whether these combinations are synergistic, additive or antagonistic. From the results, it was concluded that these new approach could possibly be give more comprehensive informations about effective use of herbicide than any other systems.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.204-208
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• 1991

In this paper, the radiation properties of a far-Infrared using a PTC thermistor, the $BaTiO_3$+1.63mol% $Al_2O_3$+3.75mol% $SiO_2$+1.25mol% $TiO_2$(1/3 $Al_2O_3+xSiO_2$+(1-x) $TiO_2$; total x: 6.67mol%) ceramics, in order to progress the grade resistivity characteristics, by adding an ethanol solution of $Mn(NO_3){\cdot}6H_2O$ was investigated. The ceramics was fabricated by wet-mill method. The sintering temperature read 1300-1350$[^{\circ}C]$ and the holding time was 3 hours. The quantity of $Sb_2O_3$ and $Al_2O_3$ for an activation of the far-infrared radiation in ceramics was doped. In sintering, R-T property was measured by varying the grade temperature. The anatase-lighting apparatus and microstructures by using XRD and SEM were observed. $Sb_2O_3$. oxides additive. affected the semiconducting and emissivity and MnO was devoted an increase of resistivity. The specimen which only $Sb_2O_3$ is added to was high appeared far-infrared emissivity and Mno was not affacted the far-infrared radiation. The ceramics shows that it is effective in the structure of the human bodies as organic bodies and can be applied as electron device.

• Journal of Ocean Engineering and Technology
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• v.25 no.3
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• pp.28-33
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• 2011

The thermal shock properties of SiC materials were investigated for high temperature applications. In particular, the effect of thermal shock temperature on the flexural strength of SiC materials was evaluated, in conjunction with a detailed analysis of their microstructures. The efficiency of a nondestructive technique using ultrasonic waves was also examined for the characterization of SiC materials suffering from a cyclic thermal shock history. SiC materials were fabricated by a liquid phase sintering process (LPS) associated with hot pressing, using a commercial submicron SiC powder. In the materials, a complex mixture of $Al_2O_3$ and $Y_2O_3$ powders was used as a sintering additive for the densification of the microstructure. Both the microstructure and mechanical properties of the sintered SiC materials were investigated using SEM, XRD, and a three point bending test. The SiC materials had a high density of about 3.12 Mg/m3 and an excellent flexural strength of about 700 MPa, accompanying the creation of a secondary phase in the microstructure. The SiC materials exhibited a rapid propagation of cracks with an increase in the thermal shock temperature. The flexural strength of the SiC materials was greatly decreased at thermal shock temperatures higher than $700^{\circ}C$, due to the creation of microcracks and their propagation. In addition, the SiC materials had a clear tendency for a variation in the attenuation coefficient in ultrasonic waves with an increase in thermal shock cycles.

• Journal of the Korean Ceramic Society
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• v.35 no.4
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• pp.364-370
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• 1998

Boron-phoshor-silicate glass was fabricated on Si substrates by FHD(Flame Hydrolysis Deposition) The microstructrue of silica soot deposited at various conditon such as composition and substrate temperature was analysed by SEM. After consolidation the refractive index and composition of the silica layer were in-vestigated. For refractive index control B, P and Ge were used as additive elements while B and Ge oxides are easily mixed into $SiO_2$, P oxide($B_2O_3$) doping is difficult because of the volatile property due to low melt-ing point. Boron-phosphorous-silicate glass (BPSG) layer were fabricated using bertical torch and optimized flame temperature substrate temperature and distance of torch and substrate. P concentration of BPSG lay-er measured 3.3 Wt% and the consolidation temperature was lower than $1180^{\circ}C$. The measured refractive index of BPSG silica layer in $1.55\;\mu\textrm{m}$ wavelength was $1.4480{\pm}1{\times}10^{-1}$ and the thickness was $22{\pm}1\;\mu\textrm{m}$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.217-223
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• 2019

The application of 3D printing technology is expanding due to the production of the complex-shape parts and the one-step manufacturing process. Moreover, various technical solutions in 3D printing are emerging through continuous research and development. Representative technologies include SLS technology, in which a desired area is sintered and laminated by irradiating a powder-type material with a laser. In addition, high-performance engineering plastic parts are being manufactured in increasing numbers. In this study, tensile specimens were fabricated from polyamide 12, a widely available polymer, and the glass bead-reinforced polyamide 12. The specimen-build orientation was divided into 0°, 45°, and 90° on the fabrication platform, and the tensile test temperature was -25℃, 25℃, and 60℃. The test results showed that the tensile modulus of both materials decreases as the build orientation becomes closer to 90°. In addition, the tensile strength of glass bead-reinforced PA12 showed more dependence on the build orientation than PA12. In addition, the tensile modulus and tensile strength decreased with increasing test temperature.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.197-202
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• 2004

The aim of this work is to improve the mechanical properties of materials for glasses lens cutting at $1920^{\circ}C$ using SrO as sintering additive. The heating rate was $15^{\circ}C/min$ and the cooling rate about $25^{\circ}C/min$ from the sintering temperature to $1000^{\circ}C$. SEM analysis and XRD of the surface of samples were carried out. Microstructures of sintered materials were strongly dependent on the composition of sintering additives. The fracture toughness and hardness were increased by increasing the SrO. Typical fracture toughness and hardness of materials for glasses lens cutting were $5.6{\pm}0.3MPa{\cdot}m^{1/2}$ and $16.2{\pm}0.5GPa$, respectively.

• Journal of Sensor Science and Technology
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• v.17 no.2
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• pp.127-132
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• 2008

The effect of $CeO_2$ as a sintering additive on the microstructure and the piezoelectric property of yPb$(Sb_{0.5}Nb_{0.5})O_3$-(1-y)Pb$(Zr_{0.52}Ti_{0.48})O_3$ ($0{\leq}y{\leq}0.1$, PSN-PZT) for a hypersonic sound speaker (HSS) application was investigated. The samples were sintered at $1250^{\circ}C$ for 2 h. The crystal structure and surface morphology of the samples were examined using XRD and FE-SEM, respectively. Study on the influence of $CeO_2$ additives on the dielectric and piezoelectric properties indicated that the $CeO_2$-added PSN-PZT system had a high piezoelectric properties. The optimized results of ${\varepsilon}_r=1209$, $K_p$=52% $d_{33}$=351(pC/N) and $Q_m$=1230.16 were obtained at 0.4 wt.% $CeO_2$-added PSN-PZT.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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• pp.59-64
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• 2008

The mechanical properties of liquid phase sintered (LPS) SiC materials, with the addition of oxide powder, were investigated, in conjunction with a detailed analysis of their microstructures. LPS-SiC materials were fabricated at a temperature of 1820 $^{\circ}C$ under an argon atmosphere, using three different starting sizes of SiC particles. The sintering additive for the fabrication of the LPS-SiC materials was an $Al_2O_3-Y_2O_3$ mixture with a constant composition ratio ($Al_2O_3/Y_2O_3$: 1.5). The particle sizes of the commercial SiC powderswere 30 nm, 0.3 $\mu$m, and 3.0 $\mu$m. The flexural strength of the LPS-SiC materials was also examined at elevated temperatures. A decrease in the starting size of the SiC particles led to an increase in the flexural strength of the LPS-SiC materials, accompanying a highly dense morphology with the creation of a secondary phase. Such a secondary phase was identified as $Y_3Al_2(AlO_4)2$. The flexural strength of the LPS-SiC materials greatly decreased with an increase in the test temperature, due to the creation of a large amount of pores.

• KSBB Journal
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• v.22 no.5
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• pp.351-355
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• 2007

Resveratrol, a polyphenolic compound with antioxidative property, was purified from the grape's twig to be used as functional additives of food and/or cosmetics. Extraction of the grape's twig was performed using 80% ethanol in ultrasonic extractor for 60 min. The crude extract was purified up to 99% after elution through silica gel open column chromatography. The stability of the purified resveratrol was as follows: a half life of 90 days at 40$^{\circ}C$ and 60 days at 25$^{\circ}C$. A sensory test of the commercial grape juice including the 1-10 ppm of purified resveratrol showed better preference than the grape juice without purified resveratrol additive. Color and smell test showed no difference between the samples. The grape twig can be used as a valuable resource for the extraction of resveratrol, which would be added to nutraceutical and cosmetic products.