• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.4
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• pp.380-391
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• 1993

The experimental study was made to propose the treatment method of wastewater in the high-density fish culture system. The BOD to COD ratios of effluents were almost same to 0.65 in the eel-farm, but were various in the farm rearing together with tilapia etc. A BOD rate curve of the eel-farm effluent could be described mathematically by the equation, $BODu=14.1(1-10^{-0.222t})+30.9(1-10^{-0.035(t-8)})$. Nitrification in Biological Fluidized Bed(BFB) system to treat the fish-farm wastewater could be reduce ammonium level up to $65{\sim}79\%$ when ammonium loading rates were between 0.014 and 0.075g $NH_4/g$ BVS-day. Nitrification efficiency was decreased by organic matters in the wastewater when ammonium loading was low(0.014 g $NH_4/g$ BVS-day). T-N removal ratios were decreased to increase loading in denitrification process, because of low C/N ratio. Based on much higher biological mass concentrations, BFB system takes many advantages of a practical viewpoint, such as stability of treatment efficiency and reduction of necessary site area for the facility, as compared with conventional treatment systems.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.3
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• pp.214-222
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• 2012

Several acidogenesis batch tests, and BMP (Biochemical Methane Potential) with food waste leachate was tested at various organic loading rates (OLRs) on the mesophilic ($35^{\circ}C$) and thermophilic ($55^{\circ}C$) conditions. In acidogenesis batch test, VS removal efficiencies were 27.3% and 30.6% at $35^{\circ}C$ and $55^{\circ}C$, respectively. Removal efficiency of VS at $55^{\circ}C$ was higher than that at $35^{\circ}C$. With decrease in VS, SCOD increased as reaction time increased. Solubilization efficiency of VS were 27.4% and 33.4% at each reaction temperature within 4 days acid fermentation. Methane yield were 461 and 413 $mLCH_4/gVS$ at mesophilic and thermophilic BMP test, respectively. SCOD solubilizations in the themophilic acid fermenter showed 8~17% higher than those in the mesophilic fermenter. COD removal efficiency showed higher in the mesophilic acid fermenter at low organic loading rate. While at high organic loading rate, it was higher in the thermophilic acid fermenter. VS removal efficiency was higher at the mesophilic temperature, however, it decreased at OLR higher than 6 kg $COD/m^3{\cdot}day$. On the contrary, VS removal efficiency did not decrease but maintain at thermophilic temperature. The amount of methane gas generated from mesophilic methanogenesis digester was 12.6, 21.6, 27.4 L/day at OLR of 4, 5, 6 $COD/m^3{\cdot}day$, respectively. The amount of methane gas generated from themophilic methanogenesis digester was 14.3, 20.6, 25.2 L/day at each OLR, respectively, which is about 15~20 L/day lower than those generated at mesophilic digester.

• Journal of the Korean GEO-environmental Society
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• v.11 no.7
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• pp.57-63
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• 2010

The necessity of effective and economical improvement for soft ground is required more and more as mountains form 70% of country. The soft ground improvement methods for ocean development are sand compaction pile method, displacement method are applied to the soft ground improvement from ocean development pre-loading method, air pressure method, well point method, pack drain method, quicklime pile method etc. Among them, the sand compaction pile method, has many problems such as the economical problem on importing materials due to the lack of sand and destroying the nature while collecting sand. To replace the sand with other alternative materials, a study on the bottom ash compaction pile method because the bottom ash has the similar engineering properties with sand. Therefore, in this study, after compose the complex soil with a replacement rate of 10~80% and a large direct shear test, shear test, consolidation test with replacement rates of bottom ash are performed to estimate whether its shear and consolidation characteristics are suitable for the alternative material of compaction pile method. As a result of test, Shear Strength Parameters tend to be increased in accordance with the increase of replacement ratio of bottom compaction pile, and Settlement Reduction Factor and $t_{90}$ tend to be decreased.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.237-244
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• 1996

Liquid-liquid extractions by use of microporous hollow fiber modules are fast compared with conventional extraction equipment because of the large surface area per volume. In these modules, the extractant and feed can be contacted at high speed and two flows are completely independent, so there are no problems with loading and channeling. In this paper, it was investigated the extraction selectivities for liquid-liquid extraction of Fe(II) and Ni(II) from dilute aqueous solution into TOA (tri-n-octylamine) and EHPNA (bis(2-ethylhexyle)hydrogenphosphite) as organic extractants by using the hydrophobic hollow fiber module. To determine the rate controlling step for mass transfer in hollow fibers, we also examined the effect of inside and outside flow rates of the hollow fiber module. From these experiments, we identified for the extraction of system with high partition coefficient in hydrophobic hollow fibers, mass transfer in the inside aqueous feed dominated the overall mass transfer, and in this paper, correlation between $K_w$ and $v_t$ was obtained as $K_w{\frac{d}{D}}=6.22\(\frac{d^2v_t}{LD}\)^{1/3}$ On the other hand, for the system with low partition coefficient, the resistance in the inside of hollow fibers was much less than membrane resistance because the extraction was not simple in the micropore. Thus, for systems with high partition coefficients, hydrophobic hollow fibers would be a better choice.

• Journal of Radiation Protection and Research
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• v.22 no.2
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• pp.77-83
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• 1997

Epoxy resin-type neutron shielding materials, KNS(Kaeri Neutron Shield)-101, KNS-102, and KNS-103 have been fabricated to be used in spent fuel shipping cask. The base material is epoxy resin, and polypropylene, aluminium hydroxide, and boron carbide are added. These shielding materials offer good fluidity at processing, which makes it possible to apply this resin shield to complicated geometric shapes such as shipping cask. The shielding property of these shielding materials for shipping cask for loading 28 PWR spent fuel assemblies has been evaluated. ANISN code is used to evaluate the shielding property of the shipping cask with the thickness of the three neutron shielding materials greater than 10 cm. As a result of analysis, the maximum calculated dose rate at the radial surface of the cask is determined to be $300{\mu}Sv/h$ and the maximum calculated dose rate at 100 cm from the cask is $97{\mu}Sv/h$. These dose rates remain within allowable values specified in related regulations.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.2
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• pp.116-126
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• 2018

Purpose: The purpose of this study was to analyze the factors affecting the survival rate and the marginal bone level of dental implants that have functioned over 7-years. Materials and Methods: In 92 patients, 178 dental implants were included. Implant-related factors (diameter, length, prosthetic splint), patient-related factors (gender, smoking, plaque index, compliance to supportive periodontal therapy) and surgery-related factors (proficiency of surgeon, bone graft) were evaluated via clinical and radiographic examination. The marginal bone level was determined by intraoral standard radiography at the mesial and distal aspects of each implant using an image analysis software program. Results: The survival rate of all the implants was 94.94% and the marginal bone level was $0.89{\pm}1.05mm$, these results are consistent with other studies that present long-term good clinical results. Implant length and plaque index among several factors were statistically significant for implant survival rate (P < 0.05). Smoking and the presence of regeneration surgery were statistically significant for the marginal bone level (P < 0.05). Conclusion: Dental implant that have functioned over 7-years showed favorable long-term survival rates and marginal bone level. Implant length and plaque control should be considered for improving the long-term clinical results. It is needed that careful application of bone regeneration technique and smoking control for maintaining of marginal bone level.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.61-66
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• 2006

The combined ADEPT(Anaerobic Digestion Elutriated Phased Treatment)-SHARON(Single reactor system for High Ammonium Removal Over nitrite)-ANAMMOX(Anaerobic ammonium oxidation) processes were operated for resources recovery and nitrogen removal from slurry-type piggery waste. The ADEPT process operated at an acidogenic loading rates of 3.95 gSCOD/L-day, the SCOD elutriation rate and acid production rate were 5.3 gSCOD/L-day and 3.3 gVFAs(as COD)/L-day, respectively. VS reduction and SCOD reduction by the hydrolysis were 13% and 0.19 $gSCOD_{prod.}/gVS_{feeding}$, respcetively. Also, the acid production rate was 0.80 $gVFAs/gSCOD_{prod}$. In methanogenic reactor, the gas production rate and methane content were 2.8 L/day($0.3m^3CH_4/kgCOD_{removal}@STP$) and 77%, respectively. With these operating condition, the removals of nitrogen and phosphorus were 94.1% as $NH_4-N$(86.5% as TKN) and 87.3% as T-P respectively.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.4
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• pp.381-390
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• 2017

In Korea, commercial nuclear power plants and research reactors have on-site storage systems for the spent nuclear fuel, but it is difficult to expand the facilities used for the storage systems. If decommissioning of nuclear power plants starts, an amount of high level radioactive waste will be generated. In this study, a radiological impact assessment of the railroad transport of high level radioactive waste was carried out considering radiation workers and the public, using the developed transport container as the transport package. The dose rates for workers and the public during the transport period were estimated, considering anticipated transport scenarios, and the results compared with the regulatory limit. A sensitivity analysis was also carried out by considering the different release ratios of the radioactive materials in the high level radioactive waste, and different distances between the transport container and workers during loading and unloading phases and while attaching another freight car. For all the anticipated transport scenarios, the radiological impacts for workers and the public met the regulatory limits.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.7
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• pp.418-425
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• 2015

Anaerobic Filters (AF) packed with porous ceramic floating media were operated at different operational conditions to identify the feasibility of the renewable bioenergy, methane production from swine wastewater and to verify the suitability of effluent from anaerobic filters for the subsequent biological nitrogen and phosphorus removal. Stepwise increase in organic loading rates (OLRs) or decrease in hydraulic retention times (HRTs) with influent TCOD concentration of 14,000 mg/L were utilized at mesophilic temperature. The maximum methane productivity of 1.74 volume of $CH_4$ per volume of reactor per day (v/v-d) was achieved at an hydraulic retention time (HRT) of 0.5 day (OLR 28 g TVS/L-d). Based on the biogas production, the highest total volatile solids (TVS) removal efficiency of 63% was obtained at an HRT of 3 days (OLR 4.67 g TVS/L-d), however based on the result from the effluent total chemical oxygen demand (TCOD) analysis, the highest TCOD removal efficiency of 75% was achieved. The effluent alkalinity concentration over the range of 2,050~2,980 mg/L as $CaCO_3$ at all operational conditions, could compensate the alkalinity destruction caused by nitrification. The effluent from the anaerobic filter operated under the HRT of 2 days showed the COD/TKN ratio of 15~35 and COD/TP ratio of 38~56. Therefore effluent C/N/P ratio is able to satisfy the optimum COD/TKN ratio of greater than 8.0 and COD/TP ratio of 33 for the subsequent biological nutrient removal.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.764-771
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• 2012

In order to develop constructed wetlands for treating hydroponic wastewater in greenhouse, actual constructed wetlands were used the obtained optimum condition in previous study, and the removal rate of pollutant in the water according to 4 kinds connection method of piping such as system A (UP-UP stream), system B (UP-DOWN system), system C (DOWN-UP stream) and system D (DOWN-DOWN stream) were investigated. Removal rate of biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), total nitrogen (T-N) and total phosphorus (T-P) by system A (UP-UP stream) connection method in actual constructed wetlands were slightly higher than other systems. At the system A, the removal rate of BOD, COD, SS, T-N and T-P were 88, 77, 94, 54 and 94%, respectively. Under different hydroponic wastewater loading, the removal rates of pollutants were higher in the order of $75L\;m^{-2}day^{-1}{\fallingdotseq}150L\;m^{-2}day^{-1}$ $$\geq_-$$ $300L\;m^{-2}day^{-1}$. Therefore, optimum connection method was system A for treating hydroponic wastewater in greenhouse.