• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.3
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• pp.126-132
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• 2002

The nanocrystalline zirconia powder with anisotropic shapes was synthesized by hydrothermal treatment of the tetragonal zirconia prepared by aging the zirconium hydroxide precipitate, which was obtained from the reaction between $ZrOCl_2{\cdot}8H_2O$ and KOH solutions under the fixed pH of 13.5, at $100^{\circ}C$ for 24 h. With increasing the hydrothermal reaction temperature and time, the fraction of tetragonal phase with spherical zirconia decreased, whereas, relatively the fraction of monoclinic phase with spindle-like and rod shape zirconia increased. As increased concentration of the NaOH solution it promoted the particle size to become larger and the crystalline phase to transform tetragonal to monoclinic. However, the specific surface area at the early stage of the reaction increased and subsequently decreased because of grain growth in powder with longer reaction time.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.70.1-70.1
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• 2010

티타늄알콕싸이드를 이용한 티타니아 입자 제조 및 $200-240^{\circ}C$ 정도의 수열처리에 의해 티타니아 입자의 물성을 제어하였고, 이를 이용하여 염료감응형 태양전지를 제조하여 티타니아 입자의 물성에 따른 태양전지 성능변화를 고찰하였다. 얻어진 티타니아 입자의 경우 수열처리 온도가 낮을수록 입자크기는 작았고 첨가되는 산농도에 따라 결정상의 제어가 가능하였다. 또한 태양전지 제조 시 입자 크기는 어느 정도 이상이 되어야 고효율 태양전지 제조에 적합하였고, 변환 효율은 9% 이상이었다.

• Journal of the Korean Ceramic Society
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• v.45 no.1
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• pp.54-59
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• 2008

Hydrated sodium silicate with 25 wt% water contents was synthesized by hydrothermal reaction using anhydrous sodium silicate. The hydrated sodium silicate was expanded at $370^{\circ}C$ for 30 min. and then pulverized, classified (- 200 mesh) and press-formed. The samples were heat treated at $400{\sim}900^{\circ}C$ for 30 min. in order to study the expansion characteristics depending on heat treatment temperature. A porous body with closed pore was formed above $600^{\circ}C$. The volume expansion ratio and the pore size were increased and the specific gravity was decreased with increasing heat treatment temperature. However, the volume expansion ratio was decreased and the specific gravity was increased above $850^{\circ}C$ due to the softening of the sodium silicate.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.146-146
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• 2016

Zinc Oxide (ZnO) was known as a promising material for surface acoustic wave devices, gas sensors, optical devices and solar cells due to piezoelectric material, large band gap of 3.37 eV and large exciton binding energy of 60 meV at room temperature. In particular, the alignment of ZnO nanostructures into ordered nanoarrays can bring about improved sensitivity of devices due to widen the surface area to catch a lot of gas particle. Oxygen plasma treatment is used to specify the nucleation site of round patterned ZnO nanorods growth. Therefore ZnO nanorods were grown on a quartz substrate with patterned polystyrene monolayer by hydrothermal method after oxygen plasma treatment. And then, we carried out nanostructures by adjusting the diameter of the arranged ZnO nanorods according to polystyrene spheres of various sizes. The obtained ZnO nanostructures was characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM).

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.154-158
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• 2001

The heat treatment of PVC film containing PVC 65%, DOP(Dioctyl Phthalate) 32% as plasticizer, Ca-Zn stearates and surface agent was peformed under several conditions to study the degradation behavior of PVC sheet. In the case of H$_2$SO$_4$, the dehydrochlorination was ca.100% at 25$0^{\circ}C$ for 3h. The char involving the smaller pores was produced with hydrothermal treatment. The pore size became small with increasing the treatment time and temperature. In the case of treatment with Ca(OH)$_2$, the sizes of pores produced in char were about sever ~ 10${\mu}{\textrm}{m}$ at 2$25^{\circ}C$ for 12h. In the case of H$_2$SO$_4$, the size of pores were about 1${\mu}{\textrm}{m}$ in 5M H$_2$SO$_4$for 12h.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.746-750
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• 2001

The heat treatment of PVC film containing PVC 65%, DOP(Dioctyl Phthalate) 32% as plasticizer, Ca-Zn stearates and surface agent was peformed under several conditions to study the degradation behavior of PVC sheet. In the case of H$_2$SO$_4$, the dehydrochlorination was ca.100% at 25$0^{\circ}C$ for 3h. The char involving the smaller pores was produced with hydrothermal treatment. The pore size became small with increasing the treatment time and temperature. In the case of treatment with Ca(OH)$_2$, the sizes of pores produced in char were about sever ~ 10${\mu}{\textrm}{m}$ at 2$25^{\circ}C$ for 12h. In the case of H$_2$SO$_4$, the size of pores were about l${\mu}{\textrm}{m}$ in 5M H$_2$SO$_4$for 12h.

• Korean Journal of Materials Research
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• v.18 no.5
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• pp.229-234
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• 2008

Porous Ti implant samples were fabricated by the sintering of spherical Ti powders in a high vacuum furnace. To increase their surface area and biocompatibility, anodic oxidation and a hydrothermal treatment were then applied. Electrolytes in a mixture of glycerophosphate and calcium acetate were used for the anodizing treatment. The resulting oxide layer was found to have precipitated in the phase form of anatase $TiO_2$ and nano-scaled hydroxyapatite on the porous Ti implant surface. The porous Ti implant can be modified via an anodic oxidation method and a hydrothermal treatment for the enhancement of the bioactivity, and current multi-surface treatments can be applied for use in a dental implant system.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.10
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• pp.1707-1711
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• 2013

In our study, each part (flesh, white rind, and green rind) of watermelon was extracted using hydrothermal extraction method at temperatures ranging from 100 to $300^{\circ}C$ at the intervals of 10, 30, and 60 min. We found that hydrothermal treatment has a significant bearing not only on tyrosinase inhibitory activity but also on neuronal cell protection of watermelon parts. The peak tyrosinase inhibitory activity (about 93%) was observed in both the flesh and green rind extracts at $300^{\circ}C$ for 60 min. In addition, we observed that hydrothermal extracts of watermelon parts at $300^{\circ}C$ for 60 min also evidenced significant protection effect for neuronal cell against $H_2O_2$ in a concentrationdependent manner. The results of this study confirm that hydrothermal treatment may be an efficient processing method for the purpose of obtaining potent bioactive substances from watermelon.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.164.2-164
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• 2003

• Korean Journal of Environmental Agriculture
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• v.35 no.2
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• pp.128-136
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• 2016

BACKGROUND: Hydrothermal carbonization reaction is the thermo-chemical energy conversion technology for producing the solid fuel of high carbon density from organic wastes. The hydrothermal carbonization reaction is accompanied by the thermal hydrolysis reaction which converse particulate organic matters to soluble forms (hydro-thermal hydrolysate). Recently, hydrothermal carbonization is adopted as a pre-treatment technology to improve anaerobic digestion efficiency. This research was carried out to assess the effects of hydro-thermal reaction temperature on the methane potential and anaerobic biodegradability in the thermal hydrolysate of organic sludge generating from the wastewater treatment plant of poultry slaughterhouse .METHODS AND RESULTS: Wastewater treatment sludge cake of poultry slaughterhouse was treated in the different hydro-thermal reaction temperature of 170, 180, 190, 200, and 220℃. Theoretical and experimental methane potential for each hydro-thermal hydrolysate were measured. Then, the organic substance fractions of hydro-thermal hydrolysate were characterized by the optimization of the parallel first order kinetics model. The increase of hydro-thermal reaction temperature from 170℃ to 220℃ caused the enhancement of hydrolysis efficiency. And the methane potential showed the maximum value of 0.381 Nm³ kg^-1-VS_added in the hydro-thermal reaction temperature of 190℃. Biodegradable volatile solid(VSB) content have accounted for 66.41% in 170℃, 72.70% in 180℃, 79.78% in 190℃, 67.05% in 200℃, and 70.31% in 220℃, respectively. The persistent VS content increased with hydro-thermal reaction temperature, which occupied 0.18% for 170℃, 2.96% for 180℃, 6.32% for 190℃, 17.52% for 200℃, and 20.55% for 220℃.CONCLUSION: Biodegradable volatile solid showed the highest amount in the hydro-thermal reaction temperature of 190℃, and then, the optimum hydro-thermal reaction temperature for organic sludge was assessed as 190℃ in the aspect of the methane production. The rise of hydro-thermal reaction temperature caused increase of persistent organic matter content.