• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.37-46
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• 2010

Marine clays are soft soil deposits having complicated mineralogy and formation characteristics. Thus, characterization of its geotechnical behavior has been a main issue for geotechnical engineers. Nowadays, the importance and applications of geophysical exploration on marine clays are increasing significantly according to the accuracy, efficiency, and reliability of geophysical survey technology. For marine clays, seismic survey is effective for density and elasticity characterization, while electro-magnetic wave provides the information about the fluid conductivity phenomena inside soil. For practical applications, elastic wave technology can evaluate the consolidation state of natural marine clay layers and estimate important geotechnical engineering parameters of artificially reclaimed marine deposits. Electrical resistivity can provide geophysical characteristics such as particle cementation, pore geometry shape, and pore material phase condition. Furthermore, nondestructive geophysical monitoring is applicable for risk management and efficiency enhancement during natural methane gas extraction from gas hydrate-bearing sediments.

• 한국지구물리탐사학회:학술대회논문집
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• 2011.10a
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• pp.113-116
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• 2011

• Geophysics and Geophysical Exploration
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• v.2 no.4
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• pp.184-190
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• 1999

A study of gas hydrate is a worldwide popular interesting subject as a potential energy source. A seismic survey for gas hydrate have performed over the East sea by the KIGAM since 1997. General indicators of natural submarine gas hydrates in seismic data is commonly inferred from the BSR (Bottom Simulating Reflection) that occurred parallel to the see floor, amplitude decrease at the top of the BSR, amplitude Blanking at the bottom of the BSR, decrease of the interval velocity, and the reflection phase reversal at the BSR. So the seismic data processing for detecting gas hydrates indicators is required the true amplitude recovery processing, a accurate velocity analysis and the AVO (Amplitude Variation with Offset) analysis. In this paper, we had processed the field data to detect the gas hydrate indicators, which had been acquired over the East sea in 1998. Applied processing modules are spherical divergence, band pass filtering, CDP sorting and accurate velocity analysis. The AVO analysis was excluded, since this field data had too short offset to apply the AVO analysis. The accurate velocity analysis was performed by XVA (X-window based Velocity Analysis). This is the method which calculate the velocity spectrum by iterative and interactive. With XVA, we could determine accurate stacking velocity. Geobit 2.9.5 developed by the KIGAM was used for processing data. Processing results say that the BSR occurred parallel to the sea floor were shown at $367\~477m$ depths (two way travel time about 1800 ms) from the sea floor through shot point 1650-1900, the interval velocity decrease around BSR and the reflection phase reversal corresponding to the reflection at the sea floor.

• Ocean and Polar Research
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• v.23 no.1
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• pp.51-62
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• 2001

The Arctic consists of numerous sedimentary basins containing voluminous natural resources and two of the world's major oil and gas producing areas. The western Siberia Basin in the Arctic region has the largest petroliferous province with an area of 800 ${\times}$ 1,200 km and produces more than 60% of total Russian oil production. The North Slope of Alaska produces about 20% of the U.S. output, i.e., 11% of the total U.S. consumption. Being small compared to those regions, the Canadian Northwest Territories and the Pechora Basin in Russia produce only fair amount of oil and natural gas. There are also many promising areas in the northern continental shelf of Russia. In addition to Russia, Svalbard and Greenland have been investigated for oil and gas. Gas hydrates are widespread in both permafrost regions and arctic continental shelf areas. The reserves of gas hydrates in the Arctic Ocean are about 20${\sim}$32% of total estimated amounts of gas hydrates in the world ocean. Mineral mining is well developed, especially in Russia. The major centers are located around the Kuznetsk Basin and Noril'sk. They are major suppliers of gold, tin, nickel, copper, platinum, cobalt, iron ore, coal as well as apatite. There are also some minings of lead-zinc in Alaska and Arctic Canada.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.580-583
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• 2008

다양한 고리형 에스테르 및 고리형 케톤 화합물을 시도하여 새로운 구조-II 및 구조-H 수용성 하이드레이트 형성체를 발견하였다. 이렇게 새로이 발견된 하이드레이트 형성체에 대해서는 상평형 측정 및 분광학적 분석을 수행하여 안정영역과 분자 거동을 파악하였다. 새로이 발견된 하이드레이트 형성체는 물과의 용해성이 우수하여 하이드레이트 형성이 빠른 속도로 이루어져 실제 응용 분야에서 중요하게 사용될 수 있을 것으로 전망된다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.577-580
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• 2007

분자 크기가 너무 커 가스 하이드레이트를 형성하지 않는다고 알려진 n-펜탄과 n-헥산이 다른 구조-H 형성 화합물과 혼합되어 사용될 경우 구조-H 동공 내에 함께 포접되는 것으로 확인되었다. 구조-H 하이드레이트의 형성 및 미세구조 분석은 고체 NMR 및 X-선 회절 분광법을 이용하여 확인하였다. 이러한 혼합 화합물에서 보이는 구조-H 하이드레이트 형성은 전체적인 구조-H 형성 화합물에서 나타나는 일반적 특징인 것으로 여겨진다.

• 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.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.666-671
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• 2012

Gas hydrates are inclusion compounds formed when small-sized guest molecules are incorporated into the well defined cages made up of hydrogen bonded water molecules. Since large masses of natural gas hydrates exist in permafrost regions or beneath deep oceans, these naturally occurring gas hydrates in the earth containing mostly $CH_4$ are regarded as future energy resources. The heat of dissociation is one of the most important thermal properties in exploiting natural gas hydrates. The accurate and direct method to measure the dissociation enthalpies of gas hydrates is to use a calorimeter. In this study, the high pressure micro DSC (Differential Scanning Calorimeter) was used to measure the dissociation enthalpies of methane, ethane, and propane hydrates. The accuracy and repeatability of the data obtained from the DSC was confirmed by measuring the dissociation enthalpy of ice. The dissociation enthalpies of methane, ethane, and propane hydrates were found to be 54.2, 73.8, and 127.7 kJ/mol-gas, respectively. For each gas hydrate, at given pressures the dissociation temperatures which were obtained in the process of enthalpy measurement were compared with three-phase (hydrate (H) - liquid water (Lw) - vapor (V)) equilibrium data in the literature and found to be in good agreement with literature values.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.501-503
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• 2007

오호츠크해 사할린 북동 해저사면지역은 세계적인 가스수화물 산출지역으로 알려져있다. 이미 2005년 탐사에서 50 cm 두께의 순수 가스수화물 시료를 해저면에서 채취한 지역이다. 2006년 탐사에서는 다양한 주파수대역의 고해상도 지구불리장비를 사용하여 탐사를 실시하였다. Side-scan Sonal와 3.5 kHz SBP 탐사, 수중음향 탐사를 통해 대규모 하도구조가 가스수화물지역의 북쪽 경계를 형성하고 있음을 밝혔다. 가스수화물의 BSR은 수심에 얕아짐에 따라 계속해서 심도가 감소하여 수심 약 300 m에서 해저면에 다다름. 이는 연구지역에서의 가스수화물 안정대의 상부경계가 약 300 m임을 시사한다 가스수화물 분출구조들은 약 1000m 수심을 경계로 천부에 분포하고, 해저면에는 원형의 가스분출구조들이 특징적으로 나타난다. 반면에 1000 m 수심보다 깊은 지역에서는 mud-dirpir의 상승구조로 판단되는 상승구조들이 해저면에 굴곡지형을 형성하고 있다. 해수중으로 분출하는 가스기둥들은 수심 111.2 m에서 1226.4 m 지점까지 다양한 수심에서 분포하며, 상승높이는 최대 750 m에 이르며, 약 150 m 수심까지 도달한다. 이는 해저에서 분출되는 메탄가스가 해수에 흡수되지 않고 해수면까지 이동하여 대기중으로 발출될 수 있음을 시사한다.

• Economic and Environmental Geology
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• v.46 no.1
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• pp.71-84
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• 2013

Most gas hydrates (GH) occur in ocean sediments. Global GH reserves are estimated to be $10^{13}{\sim}20{\times}10^{15}m^3$, which is nearly 1,000 times the amount of current world energy consumption. Methane hydrate (MH) has the potential to be developed into future natural gas resources to replace traditional oil and gas resources, and thus MH production technologies such as depressurization, inhibitor injection, thermal stimulation, and $CO_2-CH_4$ substitution need to be further developed. MH production, which is expected to be in test production until 2014 in Korea, is focused on the development of GH production technologies for use in the commercial production of methane gas. This study compares MH production technology and its ability to meet the twin goals of being both effective and environmentally friendly while taking into consideration the complex phenomena of GH decomposition.