• Journal of the Korean GEO-environmental Society
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• v.16 no.5
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• pp.5-11
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• 2015

The double sheeted permeable reactive barrier containing two different reactive materials can be applied to remediate the groundwater contaminated by nutrients and heavy metals. In this study, in order to evaluate the removal efficiency of contaminants including ammonium, cadmium and phosphate by double layered permeable reactive barrier containing zeolite and steelmaking slag, column tests were performed. In addition, nonequilibrium reaction in column tests was analyzed by two-site nonequilibrium advection-dispersion model. Column test results showed that zeolite is effective for removal of ammonium, while steelmaking slag is effective for removal of phosphate and cadmium. The sequential reaction of zeolite and steelmaking slag gave the better removal efficiency for ammonium.

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.231-243
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• 2015

Four different paddy soils collected around the Gyeongju nuclear site were treated with $^{99}TcO_4{^-}$ solution under the assumption of two contrasting contamination scenarios. Scenario I (SN-I) is for a pre-transplanting deposition of $^{99}Tc$ followed by plowing, whereas SN-II is for its deposition onto the water surface shortly after transplanting. Rice plants were grown in lysimeters in a greenhouse. Plant uptake of $^{99}Tc$ was quantified with the $TF_{area}$ ($m^2{\cdot}kg^{-1}-dry$). The SN-II $TF_{area}$ values for straws and brown rice, having been generally higher than the SN-I values, were within the ranges of $6.9{\times}10^{-3}{\sim}4.1{\times}10^{-2}$ and $5.2{\times}10^{-6}{\sim}7.3{\times}10^{-5}$, respectively. Sorption onto clay seems to have decreased $^{99}Tc$ uptake in SN-I, whereas it may have had an insignificant effect in SN-II. A phenomenon characteristic of submerged paddy soil, i.e., the development of a thin oxic surface layer may have greatly affected the rice uptake of SN-II $^{99}Tc$. The surface-water concentrations of $^{99}Tc$ were much higher in SN-II than in SN-I. For the percolating water, however, the opposite was generally true. At most 1.3% of the applied $^{99}Tc$ were leached through such percolation. The use of empirical deposition time-dependent $TF_{area}$ values was considered desirable in assessing the radiological impact of a growing-season deposition of $^{99}Tc$ onto paddy fields.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.3
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• pp.302-309
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• 2020

Early-detection and monitoring of toxic chemical gas cloud with chemical detector is essential for reducing the number of casualties. Conventional method for chemical detection and reconnaissance has the limitation in approaching to chemically contaminated site and prompt understanding for the situation. Stand-off detector can detect and identify the chemical gas at a long distance but it cannot know exact distance and position. Chemical detection UAV is an emerging platform for its high mobility and operation safety. In this study, we have conducted chemical gas cloud detection with the stand-off chemical detector and the chemical detection UAV. DMMP vapor was generated in the area where the cloud can be detected through the field of view(FOV) of stand-off chemical detector. Monitoring the vapor cloud with standoff detector, the chemical detection UAV moved back and forth at the area DMMP vapor being generated to detect the chemical contamination. The hybrid detection system with standoff cloud detection and point detection by chemical sensors with UAV seems to be very efficient as a new concept of chemical detection.

• Journal of Environmental Science International
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• v.14 no.6
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• pp.583-596
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• 2005

Samples of water, soil, and sediment were taken from 10 streams of Andong city in Gyeongbuk province in October 2004. To assess the degree of environmental pollution for each stream site, the chemical analyses of pollutants such as T-N, T-P, COD, heavy metal, organophosphorous and organochlorine pesticides, and dioxin-like PCB congeners were implemented using the standard process tests or the U. S. EPA methods. In addition, biological assessment using insect immune biomarkers was conducted on the same environmental samples to complement the chemical assessment. Except Waya stream (T-N; 2.91 mg/L, T-P; 0.16 mg/L, COD; 14.0 mg/L) with above the environmental quality standards, the T-P and COD concentrations of 9 sites are relatively low. The contents of Pb and Cd in samples taken from each stream were much lower than environmental quality standards. However, in comparison with soil samples of other streams, several times higher concentrations of Pb and Cd were found in locations at Mi, Gilan, Yeonha, and Waya stream sites. Dementon-S-methyl, diazinon, parathion, and phenthoate compounds among organophosphorous pesticides were detected as concentrations of ppb levels, respectively, from soil samples collected in the vicinity of Gilan, Mi, Norim, and Waya stream. On the other hand, 16 organochlorine pesticides and 12 dioxin-like PCB congeners selected in this study were not found in all samples. In particular, considering significant disrupting effects of Waya stream's samples on insect immune capacity, this stream seems to be contaminated with investigated and/or univestigated pollutants in this study.

• Journal of Soil and Groundwater Environment
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• v.18 no.6
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• pp.8-17
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• 2013

The contamination of chlorinated ethenes at an industrial complex, Wonju, Korea, was examined based on sixteen rounds of groundwater quality data collected from 2009 to 2013. Remediation technologies such as soil vapor extraction, soil flushing, biostimulation, and pumping-and-treatment have been applied to eliminate the contaminant sources of trichloroethylene (TCE) and to prevent the migration of TCE plume from remediation target zones. At each remediation target zone, temporal monitoring data before and after the application of remediation techniques showed that the aqueous concentrations of TCE plume present at and around the main source areas decreased significantly as a result of remediation technologies. However, the TCE concentration of the plumes at the downstream area remained unchanged in response to the remediation action, but it showed a great fluctuation according to seasonal recharge variation during the monitoring period. Therefore, variations in the contaminant flux across three transects were analyzed. Prior to the remediation action, the concentration and mass discharges of TCE at the transects were affected by seasonal recharge variation and residual DNAPLs sources. After the remediation, the effect of remediation took place clearly at the transects. By tracing a time-series of plume evolution, a greater variation in the TCE concentrations was detected at the plumes near the source zones compared to the relatively stable plumes in the downstream. The difference in the temporal profiles of TCE concentrations between the plumes in the source zone and those in the downstream could have resulted from remedial actions taken at the source zones. This study demonstrates that long term monitoring data are useful in assessing the effectiveness of remediation practices.

• Journal of Soil and Groundwater Environment
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• v.17 no.4
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• pp.44-50
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• 2012

A new type of chemical oxidation technology utilizing micro bubble ozone oxidizer and a pneumatic fracturing equipment was developed to enhance field applicability of a traditional chemical oxidation technology using hydrogen peroxide as an oxidizer for in-situ soil remediation. To find an efficient way to dissolve gaseous ozone into hydrogen peroxide, ozone was injected into water as micro bubble form then dissolved ozone concentration and its duration time were measured compared to those of simple aeration of gaseous ozone. As a result, dissolved ozone concentration in water increased by 31% (1.6 ppm ${\rightarrow}$ 2.1 ppm) and elapsed time for which maximum ozone concentration decreased by half lengthened from 9 min to 33 min. When the developed pneumatic fracturing technology was applied in sandy loam, cracks were developed and grown in soil for 5~30 seconds so that the radius of influence got longer by 71% from 392 cm to 671 cm. The remediation system using the micro bubble ozone oxidizer and the pneumatic fracturing equipment for field application was made and demonstrated its remediation efficiency at petroleum contaminated site. The system showed enhanced remediation capacity than the traditional chemical oxidation technology using hydrogen peroxide with reduced remediation time by about 33%.

• Economic and Environmental Geology
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• v.53 no.6
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• pp.695-701
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• 2020

This study aimed to monitor a pilot-scale vertical flow reactor (VFR) system being operated in long-term for water quality control of pH-neutral mine drainage containing Fe, Mn and As, discharged in D mine site. The treatment systems of VFR and zero manganese reactor (ZMR) consisted of sand/limestone, and steel slag/limestone, respectively. The systems were operated during about six months in order to evaluate their long-term treatment efficiency It was observed that both pH and alkalinity of mine drainage were remarkably increased and more than 98% of Fe, As and Mn ions was continuously removed during the tested period of time. In conclusion, the field results of this work demonstrated that the vertical flow reactor system can effectively treat mine drainage contaminated by Fe, As and Mn.

• Archives of Craniofacial Surgery
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• v.22 no.6
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• pp.319-323
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• 2021

Background: Prophylactic antibiotics are used to prevent surgical wound infection; however, proper indications must be followed with careful consideration of the risks and benefits, especially in clean or clean-contaminated wounds. Nasal bone fractures are the most common type of facial bone fracture. The most common method for treating nasal bone fracture is closed reduction, which is performed inside the nasal cavity without an incision. The purpose of this study was to determine the need for antibiotic use in the closed reduction of nasal bone fractures. Methods: A retrospective study was conducted using data from the National Insurance Service Ilsan Hospital of the Republic of Korea between 2016 and 2018. The records of patients who underwent closed reduction of nasal bone fracture were reviewed and classified according to sex, age, comorbidities, perioperative antibiotic usage, postoperative complications, nasal packing, anesthesia type, surgeon's specialty, and operation time. Results: Among the 373 patients studied, the antibiotic prescription rate was 67.3%. Just 0.8% of patients were prescribed preoperative antibiotics only, 44.0% were prescribed postoperative antibiotics only, and 22.5% were prescribed both preoperative and postoperative antibiotics. There were no cases that satisfied the definition of "surgical site infection." Furthermore, 2.1% of infection-related complications (e.g., mucosal swelling, synechia, and anosmia) occurred only in the antibiotic usage group. The use of nasal packing, anesthesia type, and surgeon's specialty did not show any difference in infection-related complication rates. Conclusion: According to the study findings, the routine use of perioperative antibiotics is not recommended in uncomplicated nasal bone fracture surgery.

• Geomechanics and Engineering
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• v.28 no.6
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• pp.547-557
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• 2022

Dune sands are poorly graded collapsible soils lacking fines. This experimental study explored the technical feasibility of sustainable invigoration of fine waste materials to improve the geotechnical properties of dune sand. The fine waste considered in this study is fine marble waste. The fine waste powder was mixed with dune sand at different contents (5, 10,15, 20, 25, 50%), where the gradation, void ratio, compaction, and shear strength characteristics were assessed for each fine marble waste -dune sand blend. The geotechnical properties of the dune sand-fine marble waste mix delineated in this study reveal the enhancement in compaction and gradation characteristics of dune sand. According to the results, the binary mixture of dune sand with 20% of fine marble waste gives the highest maximum dry density and results in shear strength improvement. In addition, a numerical study is conducted for the practical application of the binary mix in the field and tested for an isolated shallow foundation. The elemental analysis of the fine marble waste confirms that the material is non-contaminated and can be employed for engineering applications. Furthermore, the numerical study elucidated that the shallow surface replacement of the site with the dune sand mixed with 20% fine marble waste gives optimal performance in terms of stress generation and settlement behavior of an isolated footing. For a sustainable mechanical performance of the fine marble waste mixed sand, an optimum dose of 20% fine marble waste is recommended, and some correlations are proposed. Thus, for improving dune sand's geotechnical characteristics, the addition of fine marble waste to the dune sand is an environment-friendly solution.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.384-389
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• 2010

Outbreak of contagious diseases to livestock animals is becoming prevalent worldwide and consequently, tremendous numbers of the infected or culled stocks are buried on the ground as the most common disposal method. The buried animals can generate a wide range of detrimental components such as leachate, nutrient salts, and pathogenic bacteria, consequently contaminating the surround environment. This implies that regular investigations are required to monitor any possible detrimental environmental aspect occurred around burial sites. Therefore, the current study was conducted to investigate whether the soil and groundwater nearby the burial sites had been contaminated by the substances originated from the burial sites, which can be applied for the establishment of the ideal burial site construction design and post management scheme. For this, two different burial sites located in Cheonan and Pyeongtaek were selected. Cheonan and Pyeongtaek sites were constructed in 2004 and 2008, respectively and both contained dead poultry infected by avian influenza (AI). Soil and groundwater samples were collected around the sites followed by determination of the nutrient concentrations and bacteria (Salmonella, Camphylobacter, and Bacillus) existence in both soil and groundwater. Some of the soil samples showed higher EC, $NH_4$-N, $NO_3$-N concentration compared to those of the background (control) soils. Also the concentration of $NH_4$-N in some of the groundwater samples appeared to exceed the USEPA guideline value for drinking water (10 mg $L^{-1}$). These results indicated that the soil and groundwater were influenced by the burial site originated nutrients. In the soil, Bacillus was isolated in most soil samples while there were no detections of Salmonella and Camplylobacter. Due to the Bacillus existing mainly as a spore in the soils, it was considered that the frequent detection of Bacillus in the soil samples was attributed to the nutrients originated from the burial sites.