• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.4 no.1
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• pp.1-10
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• 2008

A magnetotelluric survey and geological survey have been performed to delineate deeply extended fracture systems at the geothermal field in Seokmo Island, Inchon, Korea. One borehole(BH-1) succeed to meet a large fracture system at the depth of 750 m where approximately $72^{\circ}C$ geothermal water is overflowing, while the other borehole(BH-2), which is about 200 m eastward from BH-1, failed to develop enough geothermal water even at the depth of 1,200m. Though there have been so many electric noise sources around the survey region, good quality of MT data above 1 Hz could be obtained with careful installation, remote reference processing. Inversion of MT data for two lines roughly perpendicular to the two major lineaments respectively show that the two lineaments are related to the fracture systems that are extended at least down to 1.5 km depth and inclined eastwards. From the interpretation, additional drilling for BH-2 is recommended and finally meet the fracture systems at the depth of 1,280 m and resulted in overflow of large amount of geothermal water of temperature $69.4^{\circ}C$ from BH-2.

• Korean Journal of Crystallography
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• v.12 no.2
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• pp.97-101
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• 2001

Phillipsite-type zeolite powders were synthesized from domestic coal fly ash by hydrothermal reaction with 2.0 M-3.5M NaOH solution at $80^{\circ}C{\sim}120^{\circ}C$ for 24 h. The properties of zeolite were investigated by XRD, SEM and IR spectroscopy. The effects of chemical composition of fly ash, reaction temperature and NaOH concentration on the zeolite synthesis were well appeared on IR spectra. It is found that the $TO_4$(T=Si, Al) tetrahedra have a well ordered structure as the $SiO_2$ content, synthesis temperature and NaOH concentration become high.

• 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.

• Journal of Ceramic Processing Research
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• v.20 no.3
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• pp.222-230
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• 2019

Microwave hydrothermal-assisted sol-gel method was employed to synthesize the Fe doped TiO2 photocatalyst. The morphological analysis suggests anatase phase nanoparticles of ~20 nm with an SBET area of 283.99 ㎡/g. The doping of Fe ions in TiO2 created oxygen vacancies and Ti3+ species as revealed through the XPS analysis. The reduction of the band gap (3.1 to 2.8 eV) is occurred by doping effect. The as-prepared photocatalyst was applied for removal of NOx under solar light irradiation. The doping of Fe in TiO2 facilitates 75 % of NOx oxidation efficiency which is more than two-fold enhancement than the TiO2 photocatalyst. The possible reason of enhancement is associated with high surface area, oxygen vacancy, and reduction of the band gap. Also, the low production of toxic intermediates, NO2 gas, is further confirmed by Combustion Ion Chromatography. The mechanism related NOx oxidation by the doped photocatalyst is explained in this study.

• Advances in materials Research
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• v.13 no.2
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• pp.103-114
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• 2024

Zeolites are microporous materials that find applications in different fields due to their numerous interesting properties. This research investigated the effect of leaching on unheated Ifon kaolin in dilute hydrochloric acid and sulphuric acid. The hydrothermal method synthesized zeolite-X type, and the resulting sample was characterized using different techniques. The silica/alumina ratio in the synthesized sample was approximately 5.6, while Infrared spectra confirmed that the synthesized material was Zeolite-X. Based on the X-ray diffraction patterns, other phases were also formed in addition to zeolite-X crystals. Thermogravimetry results indicated that the synthesized zeolite was relatively stable below 500℃, so its weight loss was only 13% after heating to about 200℃. A differential thermal analyzer confirmed this amount of weight loss, and endothermic and exothermic reactions were also observed for the samples calcined respectively at 700 and 900℃. Based on Brunauer-Emmett-Teller (BET) analyses, samples at 700℃ showed slower adsorption-desorption isotherms, pore volume, and sizes than those at 900℃. These results have shown that leaching and calcination temperature significantly affect the type of zeolite produced.

• Journal of Powder Materials
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• v.25 no.3
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• pp.226-231
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• 2018

F-containing $TiO_2$ nanopowders are synthesized using simple wet processes (precipitation-based and hydrothermal) from ammonium hexafluorotitanate (AHFT, $(NH_4)_2TiF_6$) as a precursor to apply as a photocatalyst for the degradation of rhodamine B (RhB). The surface properties of the prepared samples are evaluated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The results confirm that the synthesized anatase $TiO_2$ has sphere-like shapes, with numerous small nanoparticles containing fluorine on the surface. The photocatalytic activity of F-containing $TiO_2$ compared with F-free $TiO_2$ is characterized by measuring the degradation of RhB using a xenon lamp. The photocatalytic degradation of F-containing $TiO_2$ exhibits improved photocatalytic activity, based on the positive effects of adsorbed F ions on the surface.

• 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.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.3
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• pp.95-100
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• 2006

Synthesis of the non-swelling property micas was carried out by hydrothermal method. In order to artificially induce the diffusion of ions, a rotating system was attached to the hydrothermal apparatus and by adding 0.7 mm zircon beads, synthesis of the non-swelling property micas could be performed in a low temperature area. The hydrothermal conditions for the preparation of micas were a reaction temperature of $260^{\circ}C$, for 72 hrs, using $1K_2O,\;1Al(OH)_3,\;4Mg(OH)_2\;and\;6SiO_2$ as the starting materials and a 8M-KOH solution as the hydrothermal solvent. The micas obtained under these conditions were a plate shape with a size of $2.89{\mu}m$ and showed a whiteness of over 97 %. Also, through the FT-IR analysis, because the absorption peak of the $Mg_3OH$ vibration was observed at approximately $3700cm^{-1}$, it could be known that it was phlogopite of non-swelling property showing the chemical composition of $KMg_3AlSi_3O_{10}(OH)_2$. This result was very consistent with the EDS analysis where O (41.34 %), Mg (3.88 %), Al (11.45 %), Si (17.62 %) and K (25.71%) elements were detected.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.5
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• pp.175-180
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• 2016

ZnO nanoparticles were synthesized by aqueous preparation routes of a precipitation and a hydrothermal process. In the processes, the powders were formed by mixing aqueous solutions of Zn-nitrate hexahydrate ($Zn(NO_3)_2{\cdot}6H_2O$) with NaOH aqueous solution under controlled reaction conditions such as Zn precursor concentration, reaction pH and temperature. Single ZnO phase has been obtained under low Zn precursor concentration, high reaction pH and high temperature. The synthesized particles exhibited flakes (plates), multipods or rods morphologies and the crystallite sizes and shapes would be efficiently controllable by changing the processing parameters. The hydrothermal method showed advantageous features over the precipitation process, allowing the precipitates of single ZnO phase with higher crystallinity at relatively low temperatures below $100^{\circ}C$ under a wider pH range for the Zn precursor concentration of 0.1~1 M.