• 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.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.1115-1116
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• 2004

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.20-23
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• 2006

Geothermal energy is the natural heat of the Earth. Enormous amounts of thermal energy are continuously generated by the decay of radioactive isotopes of underground rocks and stored in the Earth's interior. Therefore, geothermal energy is one of the most important sustainable energy resources. Recent trends of geothermal energy exploitation technologies focus on the Earth scientific approach to geothermal heat pump system, enhanced geothermal system, aquifer thermal energy storage, underground thermal energy storage, and fluid/heat flow model ing for geothermal wells. Geothermal heat pump distribution in Korea is still in its starting phase in terms of areal utilization sense, we, however, expect to come up with national supply of over 1,000,000 toe by 2020

• Economic and Environmental Geology
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• v.40 no.4
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• pp.389-401
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• 2007

The oxygen and hydrogen isotopic composition in precipitation, groundwater and geothermal water were monitored over four-year period from 2001 to 2004 at the Yuseong catchment, Daejeon. By analyzing the long term rainfall pattern, we found out the drought cycle of 6 or 7 year. We fortunately revealed that the oxygen and hydrogen isotopic composition of rain has progressively changed to heavier isotopic ratios from 2001 to 2004. The weighted mean values of ${\delta}^{18}O\;and\;{\delta}D$ of rain are calculated to be $-7.7%o\;and\;-51%o$, respectively. These isotopic values are much heavier than those of groundwater and geothermal water collected at the same period, which indicates that the rain or snow of the study area would not immediately affect the isotopic composition of groundwater or geothermal water. Comparing with the previous data, the groundwater and geothermal water collected at 1990 and 1992 year has the heaviest isotopic composition and afterwards their isotopic composition has been progressively shifted to the direction of lighter composition field.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.445-448
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• 2007

Three boreholes (BE-1, BE-2 and BE-3) were drilled for geothermal resources development in Haengbok (Sejong) city. Monitoring of temperature, electric conductivity (EC) and piezometric head were carried out at each borehole. Temperatures were measured at 10 m depth, it ranges from 13.22$^{\cdot}C$ to 14.4$^{\cdot}C$. EC of BE-1 and BE-3 declined with time because groundwater flowed in boreholes. Barometric efficiency was analysed by piezometric head of groundwater and atmospheric pressure, it ranges from 44.8% to 71.5%. These parameters can be used for a geothermal modeling.

• Economic and Environmental Geology
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• v.39 no.5 s.180
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• pp.537-554
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• 2006

Water levels of thermal groundwater ($>30^{\circ}C$) were recorded from March 2002 to June 2006 at several monitoring wells within the Yuseong spa area. Using these data, we elucidated the long-term cyclic fluctuations of thermal groundwater levels with 1 year period. We also observed a noticeable water level variation with periods of 0.5, 1 and 7 days in most monitoring wells, which indicates relatively good hydraulic connectivity within the main hotspring area. By comparing water level variations among several wells, we found out that E-W and N-S trending geological structures should be an important control factor for emplacement and flow of thermal groundwater in the study area. It may be also inferred that geothermal source is highly associated with the hydraulic connectivity of aquifers at the Yuseong spa area.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.3 no.2
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• pp.9-15
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• 2007

Thermal conductivity of rocks is one of the most important parameters in designing a geothermal heat pump system, because heat exchange rate depends primarily on thermal conductivity of rocks. In this paper, the measurement methods of thermal conductivity, thermal conductivity of rocks, and heat exchange rate are discussed.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.75-85
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• 2006

In recent geotechnical engineering, geothermal approach has been on the horizon to deal with geoenvironmental issues, freezing and thawing problems, and seepage phenomenon in dams and embankments. In this study, geothermal characteristic through inner body of dams and its influence on the seepage flow were experimented by lab test and field instrumentation. Also, one of up-to-date temperature monitoring technique, called as multi-channel thermal line sensing, was evaluated its availability. As a result of lab test, it is found that the seepage flow has influence on the geothermal characteristic and a potential of finding phreatic line and seepage fluctuation could be possible by continuous temperature monitoring using thermal line sensing skills. These kine of geothermal information could be available to the modelling of water geo-structure interaction. Out of short-term field tests, clear water table and temperature distribution of a dam were easily found through temperature monitoring in holes located near a reservoir and holes within a depth of constant temperature layer. However, it is also found that the geothermal flow and finding seepage line could not be easily understandable through multi-channel temperature monitoring because of the existence of constant temperature field, thermal conductivity of soils and rocks, and unsaturated characteristics of geo-material. In this case, long-term geothermal monitoring is recommended to find sudden fluctuation of seepage line and amount of leakage.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.5 no.2
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• pp.13-19
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• 2009

This study describes energy and exergy analysis of the Maeeum-Ri Geothermal District Heating System(MGDHS) of Ganghwa Island, Incheon, Korea. Design data are used to assess the performance of the geothermal district heating system. Geothermal resources of MGDHS are found to be low quality with specific exergy index of 0.029. Exergy losses occur in the pumps and heat exchangers as well as in the geothermal Quid and direct discharge. As a result, the total exergy losses accounts for 5.2% in pumps, 47% in the discharge, and 3.3% in heat exchanger based on the total exergy input to the entire MGDHS. The overall energy and exergy efficiencies of the system are found to be 28.8% and 44.5%, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.166-168
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• 2005