• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.54-56
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• 2006

Single-well-gas-sparging tests were developed and evaluated for assessing the feasibility of in-situ aerobic cometabolism of trichloroethylene (TCE), using propane as a growth substrate. To evaluate transport characteristics of dissolved solutes [sulfur hexafluoride (SF6) or bromide (non-reactive tracers), propane (a growth substrate), ethylene, propylene (nontoxic surrogates to probe for CAH transformation activity), and DO], push-pull transport tests were performed. Mass balance showed about 90% of the injected bromide and about 80% of the injected SF6 were recovered, and the recoveries of other solutes were comparable with bromide and slightly higher than SF6. A series of Gas-Sparging Biostimulation tests were performed by sparging propane/oxygen/argon/SF6 gas mixtures, and temporal ground water samples were obtained from the injection well under natural gradient 'drift' conditions. The decreased time for propane depletion and the longer time to deplete SF6 as a conservative tracer indicate the progress of biostimulation. Gas-Sparging Activity tests were performed. .Propane utilization, DO consumption, and ethylene and propylene cometabolism were well demonstrated. The stimulated propane-utilizers cometabolized ethylene and propylene to produce ethylene oxide and propylene oxide, as cometabolic by-products, respectively. Gas-Sparging Acetylene Blocking tests were performed by sparging gas mixtures including acetylene to demonstrate the involvement of monooxygenase enzymes. Gas substrate degradation was essentially completely Inhibited in the presence of acetylene, and no production of the corresponding oxides was also observed. The Gas-Sparging tests supports the evidences that the successive stimulation of propane-oxidizing microorganisms, cometabolic transformation of ethylene and propylene by the enzyme responsible for methane and propane degradation.

• Journal of Soil and Groundwater Environment
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• v.20 no.4
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• pp.41-50
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• 2015

Open-loop groundwater heat pump (GWHP) system generally has benefits such as a higher coefficient of performance (COP), lower initial cost, and flexible system size. The hydrogeological conditions in Korea have the potential to facilitate the use of the GWHP system because a large number of monitoring wells show stable groundwater temperatures, shallow water levels, and high well yields. However, few studies have been performed in Korea regarding the GWHP system and the most studies among them dealt with Standing Column Well (SCW). Because the properties of the aquifer have an influence on designing open-loop systems, it is necessary to perform studies on various hydrogeological settings. In this study, the hydrogeological and thermal properties were estimated through various tests in the riverside alluvial layer where a GWHP system was installed. Under different groundwater flow velocities and pumping and injection rates, a sensitivity analysis was performed to evaluate the effect of such properties on the design of open-loop systems. The results showed that hydraulic conductivity and thermal dispersivity of the aquifer are the most sensitive parameters in terms of performance and environmental aspects, and sensitivities of the properties depend on conditions.

• Journal of Technologic Dentistry
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• v.38 no.3
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• pp.157-163
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• 2016

Purpose: It is to compare and evaluate the change of the wear rate and phase variation of the Zirconia before and after the sintering after the grinding by a high speed equipment manufactured for the Zirconia. Methods: The specimen of the sintered Zirconia was manufactured as size of $15mm{\times}15mm{\times}2mm$. The grinding has been applied to each of all pieces of each test groups for a minute fit for each condition at same speed of 50,000 rpm by a diamond bur at high speed handpiece with injection of the air and water. For the observation of the surface before and after the sintering of the each test piece, the cross section of it was observed as 100 magnification by a scanning electron microscope after it was coated by PT, and the diffraction analysis was performed by XDR to compare the crystal phase of the Zirconia. The average surface roughness value of all specimens were evaluated. The wear test was performed at room temperature by applying a load of 1kg for 120,000 cycles for the chewing period 6 months. Wear was analyzed for the enamel cusps by measurement of the vertical substance loss with a laser scanner. Conclusion: The phase variation from the tetragonal phase to the monoclinic phase was confirmed in the test group of the pre-sintered Zirconia after the grinding, and the value of the surface roughness and the wear rate was increased in experimental group.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1368-1375
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• 2004

Measurements of OH chemiluminescence in an atmospheric pressure, laboratory-scale dump combustor at equivalence ratios ranging from 0.63 to 0.89 were reported. The signal from the first electronically excited state of OH to ground state was detected through a band-pass filter with an ICCD. The objectives of this study are two: One is to see the effects of equivalence ratio on global heat release rate and local Rayleigh index distribution. To get the local Rayleigh index distribution, the line-of-sight images were inverted by tomographic method, such as Abel do-convolution. Another aim is to investigate the validity of using OH chemiluminescence acquired with an ICCD as a qualitative measure of local heat release. For constant inlet velocity and temperature, the overall intensities of OH emission acquired at different equivalence ratio showed periodic and higher value at high equivalence ratio. OH intensity averaged over one period of pressure increased exponentially with equivalence ratio. Local Rayleigh index distribution clearly showed the region of amplifying or damping the combustion instability as equivalence ratio increased. It could provide an information/insights on active control such as secondary fuel injection. Finally, local heat release rate derived from reconstructed OH images were presented fur typical locations.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.159-170
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• 2003

In this study, the mixed design of grout with hish strength.high permeation.high durability and environmental stability as the state of the art in material field was performed. Also, the subjects of grouting, grouting effects for ground conditions, and environmental effects were analyzed. According to these results, the fundamental data will be suggested as a design of grouting in the field application. The physical, mechanical and chemical characteristics with particle shape of the grouts were analyzed. Then, the gel-time of grouts, which is essential for workability and permeation range, were controlled. Also, the laboratory model grouting tests were performed to find the characteristics of solidification, permeation and durability with grouts. The ordinary portland, slag and microcement which have been used in the construction field were evaluated fur the environmental effects. To find the leaching of $Cr^{6+}$characteristics in cement grouts, $Cr^{6+}$ leaching tests were performed for the raw materials. Also, the results of leaching test were shorn by surrounding environment. Then, the unconfined compression strength tests were performed with the homo-gel samples, and the amount of changed $Cr^{6+}$ was measured by curing solution.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.109-116
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• 2010

The Water glass grouting method has been applied frequently to penetration grouting in practice, but some problems, such as decrease of durability with the elapsed time and environmentally adverse effect, are raised recently. Hence, the Earth Natural Grouting method which uses micro cement and inorganic material is developed to overcomes those problems of the water glass grouting method, and is aimed for extensive ground injection bound. Volumetric strain test, syneresis test, unconfined compression test, triaxial permeability test, in-situ permeability test and heavy metal analysis were conducted to verify application of the ENG. As the result of tests, volumetric strain, syneresis and unconfined strength of the ENG were superior to those of the Water Glass SGR and ENG was proved to be impermeable. Also it is expected that the ENG would not have an effect on environmental pollution.

• Journal of the Korean GEO-environmental Society
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• v.12 no.10
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• pp.5-12
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• 2011

Recently, NDS(Natural and Durable Stabilizer)method and other similar methods are composed of inorganic accelerating agent and the ultra-super fine cement have been studied as the ground improvement material in Korea. However, in the existing research, the chemical changing process of NDS in the strength development mechanism with the elapsed curing time and the principles of strength development did not give an explanation. For the popularization of the inorganic grout material, it determined that the mechanism verifying of the curing process had to be clearly preceded. Therefore, unconfined compression test, SEM and XRD analysis were performed by the elapsed curing time and were analyzed. In addition, the same trial for SGR method, that is the representative example of the water glass grout material, was selected as comparative target in order to distinguish properties of NDS more clearly. The result of experiment, the strength development mechanism of NDS could be investigated through the close correlation of the unconfined compression strength - SEM - XRD analysis, and excellence of a performance was confirmed.

• The Korea Journal of Herbology
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• v.28 no.3
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• pp.7-15
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• 2013

Objectives : Interruption and subsequent restoration of blood flow into the kidney result in renal injury. As an approach to preventing the renal injury, we determined the optimal conditions and the underlying mechanisms by which supernatant of hot water extract of ground Triticum aestivum L. (extract) attenuated ischemia/reperfusion (I/R) injury. Methods : One hour after administration of the extract (400 mg/kg) by intraperitoneal injection, renal I/R injury was generated by clamping the left renal artery in rats after surgical removal of the right kidney, followed by reperfusion. The maximal difference between the vehicle-treated and the extract-treated group under ketamine/xylazine or enflurane anesthetization was assessed at varying periods of ischemia (30-45 min) and reperfusion (3-48 hr), based on the renal function assessed with serum creatinine levels, tissue injury with hematoxylin/eosin staining, and apoptosis with terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling staining. Results : Enflurane anesthetization with 40 min of ischemia and 24 hr of reperfusion was identified to be the optimal condition, under which condition serum creatinine levels and tubular damage in the extract-treated group were significantly reduced compared with those in the vehicle-treated group ($1.3{\pm}0.2$ versus $2.7{\pm}0.3$ mg/dL, P < 0.01, and average score $1.8{\pm}0.1$ versus $3.5{\pm}0.3$, P < 0.01, respectively). These beneficial effects were mediated by inhibition of apoptotic cascades through attenuation of renal tissue malondialdehyde levels, Bax/Bcl-2 ratio and caspase-3 levels. Conclusions : The extract conferred renal protection against ischemia/reperfusion injury in rats by scavenging reactive oxygen species and consequently blocking apoptotic cascades, plausibly augmented by enflurane protection.

• Journal of the Korean Geotechnical Society
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• v.26 no.2
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• pp.15-22
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• 2010

A series of field pull-out tests were carried out to investigate the behaviour of multi-pressurized soil nails. Ten soil nails were constructed in weathered soil and then, subjected to pull-out loads. The test results showed that the ultimate pull-out resistances of soil nails constructed with high pressure were about 42~142% larger than those obtained from conventional soil nails. The deduced interface shear strength at the ground-grout interface was 71 kPa for conventional soil nails, while higher shear strength of 95~166 kPa was obtained for pressurized nails. The diameter of grouted borehole increased by about 12~27% compared to ordinary soil nails under low pressure. Also, the predicted value by the cavity expansion theory is in good agreement with the measured expanded radius of grout under injection pressure by field pull-out tests.

• Geophysics and Geophysical Exploration
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• v.16 no.3
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• pp.154-162
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• 2013

Vertical electrical sounding and 2D electrical resistivity survey were applied for evaluating the characteristics of alluvial layers at a groundwater artificial recharge site. The fine particles in alluvial layer, main target layer of groundwater artificial recharge, may cause clogging phenomena. In this case, electrical resistivity method is an effective technique to verify the spatial distribution of low-resistivity layers, such as saturated silts and clays. On the other hand, much attention should be paid to interpret the resistivity data in unconsolidated layers, because thick clayey overburden sometimes produces a masking effect on underlying interbedded resistive sands and gravels. Considering these points, we designed 35 points arranged in a grid form for vertical electrical sounding and 10 lines for 2D electrical resistivity survey, and concentrated our effort on enhancing the vertical and horizontal resolution of resistivity images. According to the results, 15 meters thick layers consisting of sands and gravels are located in 30 meters below ground. And the spatial distribution of silts and clays are mapped, which may cause clogging. Consequently, this approach can contribute to design and determine the location and depth of injection and observation wells for groundwater artificial recharge.