• Journal of Korean Society of Environmental Engineers
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• v.33 no.12
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• pp.861-867
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• 2011

In order to understand the extent of contamination of the sediments on the Mankyoung and Dongjin Rivers flowing into the Saemangeum Reservoir, the concentrations of ignition loss (IL), COD, total nitrogen (T-N), total phosphorus (T-P), and heavy metals (As, Cd, Cr, Pb, Zn) were measured. The average concentrations of IL, COD, and T-P were 2.40 (${\pm}2.18$)%, 2.97 (${\pm}3.06$) mg/g sediment, 0.370 (${\pm}0.351$) mg/g sediment, respectively, showing the extent of contamination is not serious. However, the concentrations of these parameters in the samples taken in year 2009 were higher than those in year 2008, indicating the contamination of sediments goes on gradually. The concentrations of T-N were in the range of 0.59~13.11 mg/g sediment with variation of locations and seasons. It was determined that the T-N contamination is serious when the concentrations were compared with the dredging guidelines of sediments in the Korean freshwaters, indicating the countermeasures are required to maintain the water quality of the Saemangeum Reservoir. The concentrations of heavy metals except chromium did not exceed the worrisome level of soil contamination stipulated by the Soil Environment Conservation Act of Korea. The high concentration of chromium to be concerned in some samples from the upstream of Mankyoung River requires source analysis and countermeasure to control the contamination.

• Journal of Animal Science and Technology
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• v.63 no.6
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• pp.1355-1361
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• 2021

Digestibility of pet food can affect the health of dog, especially of aged animals. To maintain the health of dogs in an overall good status it is necessary to provide nutritionally balanced food. For example, the digestibility of dogs was known to be decreased along aging. In addition, losing teethes is an often event in aged dogs that could induce a problem to eat a large size dry pet food. Nonetheless, few detailed information is available on the most suited feeding for aged dogs. As part of the nutritional study of food for aged dogs, in this study, we tested whether food type impacts on digestibility on adult versus senior dogs. The methodology to measure the digestibility of nutrients was chosen the index method using chromium oxide. Dogs were fed the same commercial dry or wet diets, which were supplemented with 0.5% chromium oxide. The wet food was prepared by adding twice volume of water in the dry food prior to incubated overnight (14-16 hours) at room temperature. After five days, their feces were collected up to a total weight of > 200 g which was the amount to analyze undigested nutrients in feces as 3 repeats. In the apparent total tract digestibility analysis of the experimental breed, no difference in the digestibility of crude protein, crude fat, crude fiber, ash, and energy was observed regarding the moisture content of the food. Noteworthy, the digestibility of nitrogen free extract was significantly increased in senior dogs fed dry dog food compared with adult dogs fed the same diet, whereas no difference was observed between senior and adult dogs fed wet food. The small breed dogs showed similar results to the experimental breed dogs. However, the digestibility of crude fat was additionally affected by age and food type unlike the experimental breed dogs. This finding suggests that the food moisture content affects the digestibility of nutrients in dogs with aging. Hence, it may be helpful to determine the nutrient contents in foods for senior dogs depending on the food type.

• Journal of Soil and Groundwater Environment
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• v.19 no.5
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• pp.35-44
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• 2014

In this study, the bio-phytoremediation and phytoremediation technologies were applied to the soils contaminated with total petroleum hydrocarbons (TPH) and heavy metals to evaluate the remediation efficacy from May 2012 to December 2013. Poplar (Populus bonatii Levl.) and Sun Hemp (Crotalaria juncea L.) were selected and planted in phytoremediation practice. These plants were also utilized in the bio-phytoremediation practice, with the addition of earthworm (Eisenia fetida) and petroleum-degrading bacteria (Pseudomonos sp. NKNU01). Furthermore, physiological characteristics, such as photosynthesis rate and maximal photochemical yield, of all testing plants were also measured in order to assess their health conditions and tolerance levels in adverse environment. After 20 months of remedial practice, the results showed that bio-phytoremediation practice had a higher rate of TPH removal efficacy at 30-60 cm depth soil than that of phytoremediation. However, inconsistent results were discovered while analyzing the soil at 100 cm depth. The study also showed that the removal efficiency of heavy metals was lower than that of TPH after remediation treatment. The results from test field tissue sample analysis revealed that more Zinc than Chromium was absorbed and accumulated by the tested plants. Plant height measurements of Poplar and Sun Hemp showed that there were insignificant differences of growth between the plants in remediation plots and those in the control plot. Physiological data of Poplar also suggested it has higher tolerance level toward the contaminated soils. These results indicated that the two testing plants were healthy and suitable for this remediation study.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.484-488
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• 1997

Three-dimensional finite element analyses were used to compare the stress distribution and the stability of the fixation among seven different tibial components and to investigate the effect due to implant materials in total knee arthroplasty. The components included an intact tibia(Type I), Cemented Cobalt-Chromium tibial tray implanted with a PMMA cemented Co-Cr stem(Type II), Cemented Co-Cr tibial tray with a uncemented Co-Cr stem(Type III), Cemented Ultra High Molecular Weight Polyethylene (UHMWPE) tibial tray with a cemented UHMWPE stem (Type IV), Cemented UHMWPE tray with a uncemented UHMWPE stem(Type V), Cemented Co-Cr tray without a stem(Type VI), and Cemented UHMWPE tray without a stem(Type VII). Uncemented components were assumed to have complete bony in growth and a rigid state of fixation between component and bone. The interface between bone/cement/component of cemented components was also assumed to be fully bonded. Bi-condylar forces were applied. The results indicated that Uncemented stem components provided lower bone stress shielding and stress concentration. The UHMWPE tray and stem component showed better agreement with the intact tibia than the Co-Cr Alloy tray and stem components. If the implant tray can be fixed firmed without a stem, Cemented PE tray without a stem(Type VII) may be recommended to give the best characteristics in the sense of stress distribution and stability.

• Korean Journal of Ecology and Environment
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• v.41 no.1
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• pp.66-72
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• 2008

Total metals, soluble metals, and bioavailable metals were monitored at the sediments of urban lakes located in Seoul, Korea during spring season 2006. The metals measured were zinc, arsenic, chromium, copper, nickel, and cadmium, which are known to be toxic to human health and ecosystems. The main sources of heavy metals in the lakes were urban runoff and atmospheric deposition associated with air pollution in urban areas. Extraction by using a weak electrolyte solution (0.1 M $Ca(NO_3)_2$) was used to predict bioavailability of the metals. Among the six heavy metals studied, copper was the most bioavailable, based the weak electrolyte extraction techniques. Since metal toxicity is related to metal bioavailability, the results were consistent with the high ecotoxicity of copper, compared to other heavy metals. Overall results suggest that there was no direct relationship between total and bioavailable metal concentration, although zinc, copper and cadmium show some relationships.

• Journal of Environmental Science International
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• v.24 no.10
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• pp.1253-1264
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• 2015

This study assessed the fertilizing value of struvite deposit recovered from swine wastewater in cultivating Chinese cabbage. Struvite deposit was compared with commercial fertilizers: complex, organic and compost to evaluate the fertilizing effect of struvite deposit. Laboratory pot test obviously presented that the struvite deposit more facilitated the growth of Chinese cabbage than organic and compost fertilizers even though complex fertilizer was the most effective in growing Chinese cabbage. It was revealed that the growth rate of Chinese cabbage was simultaneously controlled by phosphorus (P) and potassium (K). Also, the nutrients such as nitrogen (N), P, K, calcium (Ca) and magnesium (Mg) were abundantly observed in the vegetable tissue of struvite pot. Specifically, P was the most abundant component in the vegetable tissue of struvite pot. Meanwhile, the utilization of struvite as a fertilizer led to the lower accumulation of chromium ($Cr^{6+}$) than other pots, except for compost fertilizer pots, and no detection of cadmium (Cd), arsenic (As) and nickel (Ni) in the Chinese cabbage. The experimental results proved that the optimum struvite dosage for the cultivation of Chinese cabbage was 2.0 g struvite/kg soil. On the basis of these findings, it was concluded that the struvite deposits recovered from swine wastewater were effective as a multi-nutrient fertilizer for Chinese cabbage cultivation.

• Korean Journal of Poultry Science
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• v.21 no.2
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• pp.73-82
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• 1994

A study was conducted to develop a new analytical method to quantitate chicken dietary fiber (CDF). Four types of grain diets and 2 types of forages were used. Three broiler chicks at eight weeks of age were used in the Latin square design to estirnate the in vivo digestibility. Six quantitative analytical methods (Southgate method, total dietary fiber or TDF, acid detergent fiber or ADF, neutral detergent fiber or NDF, crude fiber or CF) including CDF were compared in this study. ADF, NDF and CF contained the lowest amount of the unavailable carbohydrate(UC). The value of TDF was higher than the values of ADF, NDF and CF and lower than CDF and the Southgate method. The value of NDF showed the lower values than the CDF, Southgate fiber and TDF. The recovery rate of the fiber in the feces was high in the TDF, ADF, NDF and CF, while CDF and Southgate fiber showed lower recovery rates. TDF, NDF, ADF, or CF can replace chromium in the digestibility test, while the CDF and Southgate fiber can not replace chrorniurn. The digestibility of TDF, NDF, ADF and CF in the chicken showed negative values or values close to zero depending on the types of feed but the digestibility of CDF and Southgate fiber showed relatively high positive values.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.647-653
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• 2020

Stainless steel is used commonly in nuclear applications for shielding radiation, so in this study, three different types of new stainless steel samples were designed and developed. New stainless steel compound ratios were determined by using Monte Carlo Simulation program Geant 4 code. In the sample production, iron (Fe), nickel (Ni), chromium (Cr), silicium (Si), sulphur (S), carbon (C), molybdenum (Mo), manganese (Mn), wolfram (W), rhenium (Re), titanium (Ti) and vanadium (V), powder materials were used with powder metallurgy method. Total macroscopic cross sections, mean free path and transmission number were calculated for the fast neutron radiation shielding by using (Geant 4) code. In addition to neutron shielding, the gamma absorption parameters such as mass attenuation coefficients (MACs) and half value layer (HVL) were calculated using Win-XCOM software. Sulfuric acid abrasion and compressive strength tests were carried out and all samples showed good resistance to acid wear and pressure force. The neutron equivalent dose was measured using an average 4.5 MeV energy fast neutron source. Results were compared to 316LN type stainless steel, which commonly used in shielding radiation. New stainless steel samples were found to absorb neutron better than 316LN stainless steel at both low and high temperatures.

• Membrane and Water Treatment
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• v.4 no.4
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• pp.265-275
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• 2013

China is one of the countries with the highest reserves of coal bed methane (CBM) in the world. Likewise, the CBM industry is significantly growing in China. However, activities related to CBM development have led to more environmental problems, which include serious environmental damage and pollution caused by CBM-produced water. In this paper, the detailed characteristics of CBM-produced water in the southern Qinshui Basin were investigated and analyzed and compared with local surface water and coal mine drainage. Most of CBM-produced water samples are contaminated by higher concentration of total dissolved solids (TDS), K (Potassium), Na (Sodium) and $NH_4$. The alkalinity of the water from coalmines and CBM production was higher than that of the local surface water. The concentrations of some trace elements such as P (Phosphorus), Ti (Titanium), V (Vanadium), Cr (Chromium), Ni (Nickel), Zn (Zinc), Ge (Germanium), As (Arsenic), Rb (Rubidium), and Pd (Palladium) in water from the coalmines and CBM production are higher than the acceptable standard limits. The ${\delta}D$ and ${\delta}^{18}O$ values of the CBM-produced water are lower than those of the surface water. Similarly, the ${\delta}D$ values of the CBM-produced water decreased with increasing drainage time.

• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.387-392
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• 2001

When cavity floor is near the pulp, polymerization of light-activated restorations results in temperature increase. This temperature increase cause by both the exothermic reaction process and the energy absorbed during irradiation. Therefore instating base is required. Most frequently used insulating base is glass ionmer. The purpose of this study was to evaluate intrapulpal temperature changes of glass ionomer according to various curing intensity and curing time. Caries and restoration-free mandibular molars extracted within three months were prepared Class I cavity of 3$\times$6mm with high speed handpiece. 1mm depth of dentin was evaluated with micrometer in mesial and distal pulp horns. Pulp chambers were filled with 37.0$\pm$0.1$^{\circ}C$ water to CEJ. Chromium-alumina thermocouple was placed in pulp horn for evaluating of temperature changes. glass ionomer material was placed in 2mm. total curing time was 40s: continuous 40s, intermittent 20s, intermittent 10s. Glass ionomer material was cured with 300mW/$\textrm{cm}^2$, 550mW/$\textrm{cm}^2$ light curing unit. The results were as follows : 1. Temperature in pulp increased as curing unit power is increased. 2. Temperature in pulp more increased continuous emission than intermittent emission.