• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.4
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• pp.429-440
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• 2015

In this study, model test equipment was developed to evaluate the hydraulic pressure reduction in appling the drainage shield tunnel and the model test for hydraulic pressure difference was performed in case of drainage and undrained conditions. In the result of model test, increase ratio of pore water pressure was decreased in drainage condition and total stress in drainage condition was smaller than that in undrained condition, so the hydraulic pressure was reduced by the groundwater inflow into the model tunnel. In the result of field instrumentation, the hydraulic pressure in the back ground of shield tunnel was small by 11~22% in comparison with the calculated hydraulic pressure ($r_w{\cdot}H$) in same groundwater level. In the result of model test and field instrumentation, it was appeared in drainage and undrained conditions that the difference between the theoretical hydraulic pressure and the real hydraulic pressure. It shows that it is possible to apply the reduced hydraulic pressure in applying the drainage shield tunnel and to reduce the segment section due to hydraulic pressure reduction.

• Journal of Plant Biotechnology
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• v.34 no.2
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• pp.111-118
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• 2007

Global warming crisis due primarily to continued green house gas emission requires impending change to renewable alternative energy than continuously depending on exhausting fossil fuels. Bioenergy including biodiesel and bioethanol are considered good alternatives because of their renewable and sustainable nature. Bioethanol is currently being produced by using sucrose from sugar beet, grain starches or lignocellulosic biomass as sources of ethanol fermentation. However, grain production requires significant amount of fossil fuel inputs during agricultural practices, which means less competitive in reducing the level of green house gas emission. By contrast, cellulosic bioethanol can use naturally-growing, not-for-food biomass as a source of ethanol fermentation. In this respect, cellulosic ethanol than grain starch ethanol is considered a more appropriate as a alternative renewable energy. However, commercialization of cellulosic ethanol depends heavily on technology development. Processes such as securing enough biomass optimized for economic processing, pretreatment technology for better access of polymer-hydrolyzing enzymes, saccharification of recalcitrant lignocellulosic materials, and simultaneous fermentation of different sugars including 6-carbon glucose as well as 5-carbon xylose or arabinose waits for greater improvement in technologies. Although it seems to be a long way to go until commercialization, it should broadly benefit farmers with novel source of income, environment with greener and reduced level of global warming, and national economy with increased energy security. Mission-oriented strategies for cellulosic ethanol development participated by government funding agency and different disciplines of sciences and technologies should certainly open up a new era of renewable energy.

• Journal of the Korean earth science society
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• v.23 no.6
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• pp.474-485
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• 2002

The object of this study is to investigate the contamination degree and the interpretation of sea water intrusion phenomena with hydrogeochemical and hydrogen-oxygen stable isotope of coastal aquifer in the Gogum area, Korea. The physical characteristics of groundwaters is the neutral pH condition and transitional Redox environments, and groundwater is affected by sea water & surface water. The chemical properties of groundwaters are showing an increase in contamination owing to the sea water intrusion, waste water from the surface and agricultural chemicals. In the case of chloride, 6 samples of the groundwater in the study area are in excess of the drinking water standard. The Piper diagram shows the contamination in GG-4 and 14 by sea water intrusion. GG-3, 7 and 13 dominate the Na-HCO$_{3}$ type water and regional (GG-14) is indicated to dominate the Na-Cl type water such as sea water. According to the Sl (saturation index), sea water is oversaturated with respect to calcite and dolomite, GG-3, 14 and 18 are approaching the saturation state. The hydrogen-oxygen stable isotope ratio of groundwaters originates in the meteoric water, and groundwaters of GG-1, 5 and 14 display high oxygen isotope value due to surface water trespass and sea water intrusion. The result of this study, GG-14 is contaminated by sea water intrusion, groundwaters expected GG-3, 7 and 13 is in progress to artificial pollution and sea water intrusion.

• Journal of Radiation Protection and Research
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• v.24 no.2
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• pp.101-108
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• 1999

The influence of the relative humidity, the temperature and the velocity of supply air on evaporation rate has been studied with non-boiling forced evaporation system in order to treat very low level radioactive liquid wastes produced from the decontamination and decommissioning activities. Experimental data on the evaporation rate have been obtained with the divers variables and experimental equation of air velocity was also obtained by the correlation of those data. The decontamination factor of this system was also obtained by the experimental data from a simulated liquid waste containing Cs-137 radio isotope ; $DF=10^4$. Since the commercial system will be operated for the treatment of the very low level radioactive liquid waste produced from decontamination & decommissioning of TRIGA Mark-II&III research reactor, the environmental assessment has been conducted to improve the operational safety. Exposure dose rate for an individual member of general public was assessed, and it showed that it was very lower than individual dose limits. The release of radioactivity of radioisotope material (Cs-137) to the environment was assessed, and result showed that it was $4.637{\times}10^{-14}\;{\mu}Ci/cc$.

• Journal of the Korean GEO-environmental Society
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• v.13 no.9
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• pp.45-51
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• 2012

The calcium hydroxide$(Ca(OH)_2)$ which is the cement hydrate flowed into the tunnel by groundwater is reacted with microorganism in the soil, carbon dioxide$(CO_2)$ and the vehicle's exhaust gas$(SO_3)$. So its by-products are precipitated at the drainage pipe and these cause the drainage clogging. By this phenomenon, Degradation of water flow at the drainage system of the tunnel occurred and also pore water pressure is increased. Hence the acceleration of seepage and degradation of lining is occurred. The purpose of this study is to evaluate the field applicability of the Quantum Stick and Magnetic treatment in prevention of scale deposits at the Namsan ${\bigcirc}{\bigcirc}$ tunnel and the Zone ${\bigcirc}{\bigcirc}{\bigcirc}$ of subway. These technologies were installed into drainpipes with their performance monitored through occasional site visits. SEM and XRD were also performed on scale collected from these drainpipes. As a result, in case which factor technology is applied, scale creation is remarkably decreased and especially Quantum Stick treatment performing better than Magnetic treatment. Therefore, additional application of Quantum Stick or Magnetic treatment to the existing drainage is expected to decrease the drainage clogging of the drainage.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.4
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• pp.62-71
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• 2013

This study was carried out to develope a pre-treatment technology for anaerobic digestion. Breaking down large particles into smaller particles enhances the performance of anaerobic digestion by increasing the hydrolysis of particles. A degree of hydrolysis is the most important factor determining the overall efficiency of methane production. Three types of pre-treatment devices (blade-type crusher, ozonization system, cavitation system) were set up and operated to crush solids in pig slurry in order to enhance biodegradability. The effect of pre-treatment on decreasing granular size within pig slurry by three experimental devices were compared. The highest performance of granulization of pig slurry was attained in a combination of blade-type crusher and ozonization system. In batch experiment, there was an improvement of the methane potential by combined pretreatment with crusher and cavitation. In case of pre-treated slurry, biogas and methane production were 325.9 L and 59.7% respectively, while, in untreated slurry, the production were lower; 298.8 L and 55.7%, respectively. These results indicate that higher anaerobic digestion efficiency of pig slurry can be obtained through the pre-treatment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.339-342
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• 2003

Sea level variations and sea surface circulations inthe Korean seas were observed by Topex/Poseidon altimeter data from 1993 through 1997. In sea level variations, the West and South Sea showed relatively high variations with comparison to the East Sea. Then, the northern and southern area in the West Sea showed the range of 20-30cm and 18-24cm, and the northern west of Jeju island and the southern west of Tsushima island in the South Sea showed the range of 15-20cm and 10-15cm, respectively. High variations in the West Sea was results to the inflow in sea surface of Yellow Sea Warm Current (YSWC) and bottom topography. Sea level variations in the South Sea was due to two branch currents (Jeju Warm Current and East Korea Warm Current) originated from Kuroshio Current (KC). In sea surface circulations, there existed remarkably three eddies circulations in the East Sea that are mainly connected with North Korea Cold Current (NKCC), East Korea Warm Current (EKWC) and Tushima Warm Current (TWC). Their eddies are caused basically to the influence of currents in sea surface circulations; Cyclone (0.03 cm/sec) in the Wonsan bay on shore with NKCC, and anticyclone (0.06 cm/sec) in the southwestern area of Ulleung island with EKWC, and cyclone (0.01 cm/set) in the northeastern area of Tushima island with TWC, respectively.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.607-628
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• 2012

The watershed of Gohyeon Stream was divided into the 10 sub-basins, and 19 sampling points were selected in their tributaries, which the characteristics of the water quality and pollution loads variance were investigated for during the rainy and dry seasons. The results of water quality analysis revealed that the upper watershed(T1~T8) of Gohyeon Stream had a feature of rural area, and its lower watershed(T9~T19) had a feature of the municipal area. The non-point pollution loads of the tributaries were estimated with 2,063, 601, 365, and 45 ton/yr of SS, COD, DIN, and DIP, respectively. The pollution loads of the parameters except DIP were generated about 60% during the rainy season, which suggested that a precipitation significantly influenced on the discharge of non-point source pollution. Meanwhile, the non-point pollution load of DIP was generated about 60% during the ordinary and dry seasons, which suggested that control of a phosphorus pollution source was significantly required during these seasons. Pearson's correlation analysis revealed that SS pollution source of the upper watershed was definitely different from that of the lower watershed, that is, the pollution load from the upper watershed was mainly caused by the discharge of SS due to soil erosion in the farmland and forest land during the rainy season, and that of the lower watershed by the discharge of sewage and municipal run-off.

• Journal of the Korea Institute of Building Construction
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• v.17 no.5
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• pp.445-451
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• 2017

Because of the supply-demand problem of aggregate, recently, the construction sites using 100% crushed sand are increasing and the use of low quality aggregate such as farmland sand is increasing too. When the low quality aggregate is used, the various quality defect of concrete such as the strength reduction, the increase of shrinkage and bleeding can be occurred. Therefore, in this study, the performance improvement PC admixture was developed to minimize the quality defect of plain concrete of basement parking area, when the low quality aggregate was used at the plain concrete of basement parking area. The slump loss to elapsed time test, the compressive strength test, the bleeding test and the drying shrinkage test were carried out.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4666-4672
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• 2011

Performance of NOx removal in SCR(Selective Catalytic Reduction) process depends on such various factors as catalyst factors (catalyst composition, catalyst form, space velocity, etc.), temperature of exhaust gas, and velocity distribution of exhaust gas. Especially the flow uniformity of gas stream flowing into the catalyst layer is believed to be the most important factor to influence the performance. In this research, the flow characteristics of a SCR process at design stage was simulated, using 3-dimensional numerical analysis method, to confirm the uniformity of the gas stream. In addition, the effects of guide vanes, baffles, and perforated plates on the flow uniformity for the inside and catalyst layer of the reactor were studied in order to optimize the flow uniformity inside the SCR reactor. It was found that the installation of a guide vane at the inlet duct L-tube part and the installation of a baffle at the upper part is very effective in avoiding chaneling inside the reactor. It was also found that additional installation of a perforated plate at the lower part of the potential catalyst layer buffers once more the flow for very uniform distribution of the gas stream.