• Tunnel and Underground Space
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• v.18 no.5
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• pp.343-354
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• 2008

A new method is suggested herein to measure the virgin earth stresses by means of a borehole. This novel concept is basically a combination of borehole stress relieving and borehole fracturing techniques. The destressing of the borehole is achieved by means of inducing thermal tensile stresses at the borehole periphery by using a cryogenic fluid such as Liquid Nitrogen($LN_2$). The borehole wall eventually develops fractures when the induced thermal stresses exceed the existing compressive stresses at the borehole periphery in addition to the tensile strength of the rock. The above concept is theoretically analyzed for its potential applicability to interpret in situ stress levels from the tensile fracture stresses and the corresponding borehole wall temperatures. Coupled thermo-mechanical numerical simulations are also conducted using FLAC3D, with thermal option, to check the validity of the proposed techniques. From the preliminary theoretical and numerical analysis, the method suggested for the measurement of in situ stresses appears to be capable of accurate estimation of the virgin stresses by monitoring tensile crack formation at a borehole wall and recording the wall temperatures at the time of crack initiation.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.4
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• pp.192-202
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• 1998

We investigated the geochemistry and environmental isotopes of granite-bedrock groundwater in the Yeongcheon diversion tunnel which is located about 300 m below the land surface. The hydrochemistry of groundwaters belongs to the Ca-HCO$_3$type, and is controlled by flow systems and water-rock interaction in the flow conduits (fractures). The deuterium and oxygen-18 data are clustered along the meteoric water line, indicating that the groundwater are commonly of meteoric water origin and are not affected by secondary isotope effects such as evaporation and isotope exchange. Tritium data show that the groundwaters were mostly recharged before pre-thermonuclear period and have been mixed with younger surface water flowing down rapidly into the tunnel along fractured zones. Based on the mass balance and reaction simulation approaches, using both the hydrochemistry of groundwater and the secondary mineralogy of fracture-filling materials, we have modeled the low-temperature hydrogeochemical evolution of groundwater in the area. The results of geochemical simulation show that the concentrations of Ca$\^$2＋/, Na$\^$＋/ and HCO$_3$and pH of waters increase progressively owing to the dissolution of reactive minerals in flow paths. The concentrations of Mg$\^$2＋/ and K$\^$＋/ frist increase with the dissolution, but later decrease when montmorillonite and illitic material are precipitated respectively. The continuous adding of reactive minerals, namely the progressively larger degrees of water/rock interaction, causes the formation of secondary minerals with the following sequence: first hematite, then gibbsite, then kaolinite, then montmorillonite, then illtic material, and finally microcline. During the simulation all the gibbsite is consumed, kaolinite precipitates and then the continuous reaction converts the kaolinite to montmorillonite and illitic material. The reaction simulation results agree well with the observed, water chemistry and secondary mineralogy, indicating the successful applicability of this simulation technique to delineate the complex hydrogeochemistry of bedrock groundwaters.

• Journal of Trauma and Injury
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• v.26 no.2
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• pp.39-46
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• 2013

Purpose: Non-invasive blood pressure measurement is widely used as a pre-hospital triage tool for blunt trauma patients. However, scant data exits for using the mean arterial pressure (MAP), compared to the systolic blood pressure, as a guiding index. The aim of this study was to determine the association between adverse outcomes and mean arterial pressure (MAP) and to exhibit the therapeutic range of the MAP in adult blunt trauma patients. Methods: The electronic medical records for all trauma patients in a single hospital from January 2010 to September 2012 were retrospectively reviewed. Patients below 17 years of age, patients with penetrating injuries, and patients with serious head trauma (injuries containing any skull fractures or any intracranial hemorrhages) were excluded. Adverse outcomes were defined as one of the following: death in the Emergency Department (ED), admission via operating theater, admission to the intensive care unit, transfer to another hospital for emergency surgery, or discharge as hopeless. Results: There were 14,537 patients who met entry criteria. Adverse outcomes occurred for MAPs in range from 90 to 120 mmHg. Adverse outcomes were found, after adjusting for confounding variables, to occur increasingly as the MAP declined below 90 mmHg or rose above 120 mmHg. Conclusion: Not only lower but also higher mean arterial pressure is associated with increased adverse outcomes in adult blunt trauma patients. Thus, patients with a MAP above 120 mmHg should be considered as a special group requiring higher medical attention, just as those with a MAP below 90 mmHg are.

• The Korean Journal of Nuclear Medicine
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• v.28 no.1
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• pp.89-97
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• 1994

Although bone scan is a highly sensitive test for detecting bone metastasis, its findings are often limited in specificity and cannot be used for assessing the bone marrow. Bone marrow scintigraphy may provide useful information but previous experience with radiolabelled colloid has been disappointing. Recently, $^{99m}Tc$ labeled anti-granulocyte monoclonal antibody (anti-NCA-95 MAb) has been introduced as a new bone marrow imaging agent. To evaluate the usefulness of $^{99m}Tc$ anti-NCA MAb bone marrow scans for detecting skeletal metastasis, bone marrow scans of 44 malignant tumor patients were evaluated and compared with bone scan findings. Bone scan showed abnormal lesions in 26(59%) cases, and 18 of these patients also had an abnormal bone marrow scan. Seven of the 8 patients who had normal bone marrow scan despite bone scan lesions were confirmed to be free from metastasis. There was one case with a marrow defect despite normal bone scan but the presence of metastasis was not determined due to loss of follow up. Bone scan demonstrated a total of 64 lesions while bone marrow scan showed 38 lesions. Fifty percent (32/64) of the bone scan lesions had matching marrow defects while the remaining 50% did not. Most of these non matched lesions were suggested to be nonspecific lesions such as rib fractures or degenerative change. Meanwhile bone marrow scan was able to detect 6 new lesions not detected by bone scan, bit metastasis in each lesion was not confirmed. Bone marrow scan was also helpful in assessing equivocal bone scan lesions to be of metastatic nature in 10 patients by demonstrating a matched marrow defect. Thus $^{99m}Tc$ anti-NCA MAb bone marrow scan can help exclude metastasis in patients with nonspecific bone scan lesions and may be able to detect metastatic lesions not seen with bone scan. It appears useful as a complementary study to bone scan in evaluating malignant tumor patients.

• Journal of the Mineralogical Society of Korea
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• v.25 no.2
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• pp.63-76
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• 2012

Tachylite, black basaltic glass formed by the rapid cooling of molten basalt, locally occurs at the Basaltic Agglomerate Formation (BAF), the lowest formation of Ulleung Island. The purposes of this study are to characterize the occurrence and mineralogy of tachylite and to elucidate its formation condition, with emphasis on its fracture pattern, which can serve as implications for the early volcanic activity of Ulleung Island. To this end, we investigated the occurrence pattern of tachylite in the field and carried out mineralogical analyses using optical microscope, XRD, EPMA, and SEM. Tachylite occurs at the chilled margin of basic dikes which are distributed in Naesujeon, Dodong and Jeodong seasides, Turtle Rock, and Yaerimwon, whose widths vary from several cm to 10 cm. It is evident that the outer surface of tachylite is dense and smooth, whereas the inner surface, if fractured, is characterized by conchoidal fracture. The matrix of tachylite consists of amorphous, glass and some fine-grained phenocrysts present in tachylite include biotite, anorthoclase, sanidine, plagioclase, hornblende, and Fe-Ti oxides. The fracture patterns characteristic of tachylite are subrounded, oval, or less commonly polygonal, bounded by joints to form globule or lump. Taking into account texture and mineralogy, tachylite is interpreted to have undergone little subsequent alteration at low temperature via hydration or hydrolysis that could form clay minerals after it was formed. Because tachylite with peculiar fractures occurs as dikes in a close association with BAF, its presence is considered as reliable evidence that when tachylite formed, the most part of BAF was still under subaqueous conditions, or at least saturated with seawater.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.4
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• pp.265-282
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• 2008

Based on the site characterization works in a low and intermediate level waste(LILW) repository site, the numerical simulations for groundwater flow were carried out in order to understand the groundwater flow system of repository site. To accomplish the groundwater flow modeling in the repository site, the discrete fracture network(DFN) model was constructed using the characteristics of fracture zones and background fractures. At result, the total 10 different hydraulic conductivity(K) fields were obtained from DFN model stochastically and K distributions of constructed mesh were inputted into the 10 cases of groundwater flow simulations in FEFLOW. From the total 10 numerical simulation results, the simulated groundwater levels were strongly governed by topography and the groundwater fluxes were governed by locally existed high permeable fracture zones in repository depth. Especially, the groundwater table was predicted to have several tens meters below the groundwater table compared with the undisturbed condition around disposal silo after construction of underground facilities. After closure of disposal facilities, the groundwater level would be almost recovered within 1 year and have a tendency to keep a steady state of groundwater level in 2 year.

• Economic and Environmental Geology
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• v.35 no.4
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• pp.355-368
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• 2002

The multi-storied Daewonsa stone pagoda (Treasure No. 1112) in the Sancheong, Korea was studied on the basis of deterioration and geological safety diagnosis. The stone pagoda is composed mainly of granitic gneiss, partly fine-grained granitic gneiss, leucocratic gneiss, biotite granite and ceramics. Each rock of the pagoda is highly exfoliated and fractured along the edges. Some fractures in the main body and roof stones are treated by cement mortar. This pagoda is strongly covered with yellowish to reddish brown tarnish due to the amorphous precipitates of iron hydroxides. Dark grey crust by manganese hydroxides occur Partly, and some Part coated with white grey gypsum and calcite aggregates from the reaction of cement mortar and rain. As the main body, roof and upper part of the pagoda, the rocks are developed into the radial and linear cracks. Surface of this pagoda shows partly yellowish brown, blue and green patchs because of contamination by algae, lichen, moss and bracken. Besides, wall-rocks of the Daewonsa temple and rock aggregates in the Daewonsa valley are changed reddish brown color with the same as those of the pagoda color. It suggests that the rocks around the Daewonsa temple are highly in iron and manganese concentrations compared with the normal granitic gneiss which color change is natural phenomena owing to the oxidation reaction by rain or surface water with rocks. Therefore, for the attenuation of secondary contamination, whitening and reddishness, the possible conservation treatments are needed. Consisting rocks of the pagoda would be epoxy to reinforce the fracture systems for the structural stability on the basements.

• Economic and Environmental Geology
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• v.30 no.3
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• pp.197-207
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• 1997

Rocks in the Cheongsong mine area consist of Precambrian gneiss, Cretaceous sedimentry rocks and late Cretaceous quartz porphyry. The Cheongsong deposit is composed of many hydrothermal quartz veins of strikes $N30^{\circ}{\sim}60^{\circ}W$, dips $60{\sim}85^{\circ}E$ which fill WNW fault system. Pyrite and hematite occur within transparent quartz near margins of early stage II, and milky quartz of middle stage II coexists with sphalerite, chalcopyrite and galena coexisting with Cu-Pb-Bi minerals in center part of stage II quartz veins. Stage III calcite vein filled cracks or fractures of earlier quartz veins contains native copper and chalcopyrite. Supergene minerals are chalcocite, covellite, malanchite and chrysocolla. Alteration minerals are sericite, chlorite, argillite, epitode and pyrite. Ranges of salinities and homogenization temperatures for fluid inclusions in the individual periods of stage II are: 3.7 to 7.8 wt.% eq. NaCl and 200 to $380^{\circ}C$ in transparent quartz of early stage II; 0.7 to 6.4 wt.% eq. NaCl and 200 to $320^{\circ}C$ in milky quartz of middle stage II; 0.0 to 0.9 wt.% eq. NaCl and 250 to $320^{\circ}C$ in calcite of late stage II. Those of stage III calcite range about 0 wt.% eq. NaCl, and from 140 to $260^{\circ}C$, respectively. The relationship between salinities and temperatures shows decrease tendency with paragenetic time from stage II to III. The ${\delta}^{18}O_{H_2O}$ value is 0.5‰ in stage I, range from 0.5 to -0.4‰ in stage II, and from -3.2 to -3.7‰ in stage III. Calcite in the stage II and stage III has ${\delta}^{13}C$ values of -5.0‰ and -4.5 to -4.9‰, respectively. There is a decrease in sulfur fugacity values with paragenetic time of stage II, from $10^{-6.3}$ atm for early mineralization, to $10^{-6.5}$ atm for middle stage, to $10^{-8.0}$ atm for late mineralization of stage II. The results of stable isotope and fluid inclusion indicate that ore fluids reacted with meteoric water and wall rock in the Cheongsong hydrothermal system.

• Economic and Environmental Geology
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• v.43 no.4
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• pp.371-379
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• 2010

Fresh water injection test in a fractured bedrock aquifer was applied as an efficient approach to lower saline concentrations in the saltwater-freshwater transition zone formed by seawater intrusion in a coastal area. The methodology and effectiveness of fresh water injection for hydraulically controlling seawater intrusion is overwhelmingly site dependent, and there is an urgent need to characterize the permeable fractures or unconsolidated porous formations which can allow for seawater flow and transport. Considering aquifer characteristics, injection and monitoring boreholes were optimally designed and completed to inject fresh water through sand layer and fractured bedrock, respectively. We devised and used the injection system using double packer for easy field operation and maintenance. Overall fracture distribution was systematically identified from borehole image logs, and the section of fresh water injection was decided from injection test and monitoring. With fresh water injection, the fluid electrical conductivity of the monitoring well started to be lowered by the inflow of fresh water at the specific depth. And this inflow leaded to the replacement of the fluid in the upper parts of the borehole with fresh water. Furthermore, the injection effect lasted more than several months, which means that fresh water injection may contribute to the mitigation of seawater intrusion in a coastal area.

• The Journal of Engineering Geology
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• v.8 no.1
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• pp.35-49
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• 1998

To interpret the movement historv of the Yangsan fault, the paleostresses were analyzed from about 1,000 striated small faults and 330 extension joints which were measured from 37 sites near and along the strike of the Yangsan fault from Yangsan-si, Kyeongsangnam-do to the Shinkwang-myeon, Kyeongsangbuk-do. Six sequential tectonic events have boen established as followings: (I) NW-SE extension, (Il) ENE-WSW compression and NNW-SSE extension, (III) NW-SE compression, (W) ENE-WSW extension, (V) E-W comoression and N-S extension, and (VI) NNE-SSW compression and(VI) NNE-SSWextension. The movement history of the Yangsan fault rnrning in NNE direction were inteepreted based on these six sequential stress fields. The initial feature of the Yangsan fault was formed at the first stage with the development of extension fractures by tectonic event (I) of NW-SE extension. The fault was acted continuously with a right-1ateral strike-slip movement by tectonic event( II) closely related to event( I). The movements had been continued until the Late Miocene. This age was the most active period in faulting. The left-lateral strike-slip movement was followed by subsequent tectonic events (ffi) and (IV). The activity of the Yangsan fault was suspended temporarily by compression of tectonic event (V) which was perpendicular to the strike of the fault. This period might be very short and the magnitude of the tectonic was also small. In the last stage, the fault acted with slight extension or right-lateral moveenent by tectonic event (VI).