• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.122.2-122.2
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• 2011

Sulfur hexafluoride ($SF_6$), one of the most potent greenhouse gases, is known as a hydrate former and has been studied at the high pressure up to 1.3 GPa with gas mixtures and with aqueous surfactant. Since we regard $SF_6$ as a potential promoter molecule that can stabilize hydrate structure more effectively compare to the other promoters, further investigation is required to verify the stabilizing ability of $SF_6$ in the hydrate structure. However, the insoluble nature of $SF_6$ in water or gases hinders fine scale analyses. This work discusses the data obtained by using molecular dynamics simulations of structure II (sII) clathrate hydrates containing $SF_6$ and $H_2$. The simulations were performed using the TIP4P/Ice model for water molecule and a previously reported $SF_6$ molecular model (optimized at the pure $SF_6$ single phase system (Olivet and Vega, 2007)), and a $H_2$ molecular model (adapted from the THF+$H_2$ hydrate system (Alavi et al., 2006)). The simulations are performed to observe the stability of $SF_6$ and $H_2$ in the sII clathrate hydrate system with varying temperature and pressure conditions and occupancies of $SF_6$ and $H_2$, which cannot be easily tuned experimentally. We observe that stability of H2 enclathrated in the hydrate structure more affected by the occupancy of $SF_6$ molecules and temperature than pressure, which ranges from 1 to 100 bar.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.634-637
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• 2005

Multichannel seismic data acquired in Ulleung Basin of East Sea for gas hydrate exploration. The seismic sections of this area show strong BSR(bottom simulating reflections) associated with methane hydrate occurrence in deep marine sediments. Very limited information is available from deep sea drilling as the risk of heating and destabilizing the initial hydrate conditions during the processing of drilling is considerably high. Not so many advanced status of gas hydrate exploration in Korea, the most of information of gas hydrate characteristics and properties are inferred from seismic reflection data. In this study, The AVO analysis using the long offset seismic data acquired in Ulleung Basin used to explain the characteristics and structure of gas hydrate. It is used primarily P-wave velocity accessible from seismic data. To make a good quality of AVO analysis input data, seismic preprocessing including 'true gain correction', 'source signature deconvolution', twice velocity analysis and some kinds of multiple rejection and enhancing the signal to noise ratio processes is carried out very carefully. The results of AVO analysis, the eight kinds of AVO attributes are estimated basically and some others of AVO attributes are evaluated for interpretation of AVO analysis additionally. The impedance variation at the boundary of gas hydrate and free gas is estimated for investing the BSR characteristics and properties. The complex analysis is performed also to verifying the amplitude variation and phase shift occurrence at BSR. Type III AVO anomaly appearance at saturated free gas area is detected on BSR. It can be an important evidence of gas hydrate deposition upper the BSR.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.63-67
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• 2016

Mineral hydrate is a new insulation material that compensates for the defects of existing materials. Mineral hydrate is made of inorganic ingredients; therefore, it is nonflammable. The porous structure of mineral hydrate makes the material lightweight and insulating. Mineral hydrate insulation and similar products have been studied and manufactured in Korea and abroad. However, these insulation materials need to improve in terms of strength. In this study, basalt fiber was used to enhance the strength. In order to observe the property changes, compressive strength, heat conductivity, and specific gravity were measured and XRD pattern analysis was performed. These tests confirmed that basalt fiber was effective at improving the strength and lowering the heat conductivity of mineral hydrate insulation.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.705-708
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• 2009

For the Gas hydrate Research and Development in Korea, the prospect area I & II was surveyed and drilled during the first phase. At the result, we succeeded to discovering gas hydrate real sample at BSR reflection and vent structure. This expedition processing contributes to developing the offshore seismic survey technologies and data processing of Korea. But Korean gas hydrate test production research, in spite of activating test production at other countries, is such a limitation about technician, GH production technologies and E&P processing. First of all, there is no exist in Korea to application site for the their production research results. In this paper, we have studied the gas hydrate reservoir selection technics of the DOE & BPXA for the ANS test production. And this result will helpful to preparation of gas hydrate test production in Korea.

• Journal of the Korean Institute of Gas
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• v.5 no.3 s.15
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• pp.55-62
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• 2001

This paper describes about the formation of methane hydrate that is artificially made in jacket-type stirred reactor and is observed the change of hydrate shape during the course of reaction. The combustion of manufactured methane hydrate is showed the probability of a storage and transport of gas. And the influence of various experimental conditions of temperature, pressure and stirring rate on the manufacture of methane hydrate is measured. The growth rate and the induction time of methane hydrate is observed according to the conditions. Especially it is important to investigate the effect of temperature and pressure on the growth of hydrate such as the nuclear creation and the structure formation of hydrate in order to study the storage and transport of gas.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.680-681
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• 2009

On the basis of seismic interpretation, seismic indicators of gas hydrate and associated gas such as bottom simulating reflector (BSR), acoustic blanking, column structure, gas seepage, enhanced reflection were identified in the Ulleung Basin. Fractures, faults, sandy layer could be the migration pathways transporting fluid and gas to stability zone. The formation of gas hydrate in the Ulleung Basin include: (1) nodules, veins, layers in muddy sediments and disseminated forms in sandy layer within localized column structure, (2) disseminated forms in sandy layer, and (3) disseminated forms in sandy layer just above BSR.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.387-390
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• 2006

We report here that under strong attacksof external $CH_4$ guest molecules the sII and sH methane hydrates are structurally transformed to the crystalline me framework of sI, leading to favorable change of the lattice dimension of the host-guest networks. The High Power Decoupling $^{13}C$ NMR and Raman spectroscopies were used to identify structure transitions of the mixed $CH_4+C_2H_6$ hydrates (sIIl) and hydrocarbons (methylcyclohexane, isopentane) + $CH_4$ hydrates (sH). The resulting spectra indicate that most of the synthesized sII and sH hydrates were transformed to methane hydrate of sl under 110 bar and particularly the coexistence of sl with sII or sH appear according to the surrounding methane-rich gas conditions. The present findings might be expected to Provide rational evidences regarding the preponderant occurrence of naturally-occurring sI methane hydrates in marine sediments.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.150.2-150.2
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• 2011

Unlike non-ionic clathrate hydrates stably formed by van der Waals interaction between a guest molecule and a surrounding host framework, ionic clathrate hydrates are stabilized by ionic interaction between an ionic guest molecule and the host water-framework. Here, we firstly described the stable entrapment of the superoxide ions in ${\gamma}$-irradiated $Me_4NOH+O_2$ hydrate. Owing to peculiar direct guest-guest ionic interaction, the lattice structure of ${\gamma}$-irradiated $Me_4NOH+O_2$ hydrate shows significant change of lattice contraction behavior even at relatively high temperature(120K). Particularly, we note that ionic-induced dimensional change is much greater than thermal-induced change. Such findings are expected to provide useful information for a better understanding of unrevealed nature of clathrate hydrate fields.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.690-695
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• 2012

Gas hydrate is an inclusion compound consisting of water and low molecular weight gases, which are incorporated into the lattice structure of water. Owing to its promising aspect to application technologies, gas hydrate has been widely studied recently, especially $CO_2$ hydrate for the CCS (Carbon Capture and Storage) issue. The key point of $CO_2$ hydrate technology for the CCS is how to produce gas hydrate in an efficient and economic way. In this study, we have tried to study the characteristic of gas hydrate formation using micro-sized ice through an ultrasonic nozzle which generate 2.4 MHz frequency wave. $CO_2$ as a carrier gas brings micro-sized mist into low-temperature reactor, where the mist and carrier gas forms $CO_2$ hydrate under $-55^{\circ}C$ and atmospheric pressure condition and some part of the mist also remains unreacted micro-sized ice. Formed gas hydrate was average 10.7 of diameter at average. The starting ice particle was set to constant pressure to form $CO_2$ hydrate and the consumed amount of $CO_2$ gas was simultaneously measured to calculate the conversion of ice into gas hydrate. Results showed that the gas hydrate formation was highly suitable because of its extremely high gas-solid contact area, and the formation rate was also very high. Self-preservation effect of $CO_2$ hydrate was confirmed by the measurement of $CO_2$ hydrate powder at normal and at pressed state, which resulted that this kind of gas storage and transport could be feasible using $CO_2$ hydrate formation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.144-145
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• 2021

Calcium silicate hydrate(C-S-H) is the principal binding phase that controls the strength and thermal stability of concrete. However, the effects of high temperature on the lattice structure and interatomic structure of C-S-H remains poorly understood due to its nanocrystallinity. This study aims to elucidate the change in interatomic distance of synthetic C-S-H with different Ca/Si molar ratios after exposure to high temperature via high energy X-ray scattering experiment which is a powerful analytical tool for amorphous materials.