• Journal of the korean society of oceanography
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• v.34 no.3
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• pp.179-183
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• 1999

A light-weight multiple piston corer to meet increasing coring needs in areas where R/V access is limited, is designed and discussed. Hydraulically-damped and spring-driven piston system not only virtually undisturbed surface sediments but also facilitate the recovery and subsequent operation including pore water extraction and core slicing on board the ship. It is designed as compact, light-weight and easy to dissemble that whole gear can be carried by small passenger vehicle yet it permits thick-walled core tube for thermal insulation or large opening core tubes. Because single spring instead of heavy weights of conventional gravity-driven multiple corers is used, this device is very simple and cheap to construct.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.419-423
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• 2006

Basic studies on natural gas hydrates in the East Sea were been carried out by the Korea Institute of Geoscience and Mineral Resources (KIGAM) from 2000 to 2004 involving 2D multichannel seismic lines and piston coring. 27 piston cores recovered from the deed-water Ulleung Basin of the East Sea were analyzed in this study. In piston cores cracks generally developed parallel to bedding suggest significant gas content. The core analyses showed high total organic carbon (TOC) content, sedimentation rate and heat flow of sediments. The cores recovered from the southern study area show also high residual hydrocarbon gas concentrations for the formation of natural gas hydrates. This study indicates that there is the potential for the generation of biogenic gas and the formation of natural gas hydrates in the near seafloor sediments of the study area.

• Water for future
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• v.35 no.5
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• pp.21-30
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• 2002

The inflow into a multi-purpose dam reservoir contains many suspended solids from the upper stream during the rainy season. Concentrations of SS increased to 73.3 mg/l and the TP measurement increased to 0.09 mg/l during the rainy season in 1999. It was discovered that particles less than $10\;\mu\textrm{m}$ in size composed about 50% of the total amount. Some of these particles reduce the reservoir capacity and have an impact on water. In this study, the sediment depth at Daecheong multi-purpose dam was examined. Piston coring was performed at 9 locations At Hoenam 1 out of 9 locations examined showed maximum depth, which was 90 cm and at Muneui 3 showed the minimum depth, which was 35 cm. At Hoenam, the release rate of TN was found to be $62.14~84.72\;mg/\textrm{m}^2{\cdot}day$ in 1998. However, it was found to considerably reduced to $23.20\;mg/\textrm{m}^2{\cdot}day$ in 2001. The release rate of TP was measured at $13.02~14.38\;mg/\textrm{m}^2$.day at 1998, and it was reduced to $6.93mg/\;mg/\textrm{m}^2{\cdot}day$ in 2001.

• Geophysics and Geophysical Exploration
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• v.11 no.1
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• pp.52-59
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• 2008

We have developed a new deep-towed marine DC resistivity survey system. It was designed to detect the top boundary of the methane hydrate zone, which is not imaged well by seismic reflection surveys. Our system, with a transmitter and a 160-m-long tail with eight source electrodes and a receiver dipole, is towed from a research vessel near the seafloor. Numerical calculations show that our marine DC resistivity survey system can effectively image the top surface of the methane hydrate layer. A survey was carried out off Joetsu, in the Japan Sea, where outcrops of methane hydrate are observed. We successfully obtained DC resistivity data along a profile ${\sim}3.5\;km$ long, and detected relatively high apparent resistivity values. Particularly in areas with methane hydrate exposure, anomalously high apparent resistivity was observed, and we interpret these high apparent resistivities to be due to the methane hydrate zone below the seafloor. Marine DC resistivity surveys will be a new tool to image sub-seafloor structures within methane hydrate zones.