• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.758-766
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• 2008

To evaluate homologue patterns and removal efficiency before and after water treatment, the concentrations of dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (Co-PCBs) were determined in 122 samples from 42 drinking water treatment plants throughout Japan over a two year period. The mean concentrations and toxic equivalent (TEQ) values of dioxins in raw and treated waters were 60.24 pg/L (0.14 pg-WHO-TEQ/L) and 4.15 pg/L (0.016 pg-WHO-TEQ/L), respectively. The dioxins contribution ratio of drinking water in relation to dioxins tolerable daily intake (TDI, 4 pg-TEQ/kg/day) was 0.016%. The mean TEQ removal rate of dioxins by drinking water treatment was over 88%. However, the mean removal rate of 2, 3, 7, 8-TeCDF (tetrachlorodibenzofuran) by water treatment in the 122 samples was minus 17%. Therefore, to identify which process affected the level of 2, 3, 7, 8-TeCDF, the removal efficiencies at both the advanced and conventional water treatment plants were investigated. For the TEQ removal rate across the processes, the dioxin congeners, TeCDF and non-ortho-PCBs remarkably indicated minus values after chlorination in both the advanced and conventional water treatments plant. From this study, the level of 2, 3, 7, 8-TeCDF was found to be increased as a result of chlorination.

• Progress in Superconductivity and Cryogenics
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• v.20 no.2
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• pp.6-10
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• 2018

Removal of iron oxide scale from feed-water in thermal power plant can improve power generation efficiency. We have proposed a novel scale removal system utilizing High Gradient Magnetic Separation (HGMS). This system can be applied to high temperature and pressure area. We have conducted the lab-scale model experiments using ${\varphi}50mm$ filters and it demonstrated high removal efficiency in HGMS, but scale-up of the system is required toward practical use. In this study, we conducted a large scale mock-up HGMS experiment. We used the superconducting solenoidal magnet with ${\varphi}400mm$ bore and demonstrated that our HGMS system can achieve sufficient scale removal capacity that is required to introduce into both off-line and on-line system.

• Journal of the Korean Institute of Gas
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• v.20 no.2
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• pp.1-9
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• 2016

Combined removal of n-heptane and carbon monoxide (CO) using a plasma-catalytic process was investigated. The performance of the plasma-catalytic process was compared with that of the catalyst-alone process to characterize the decomposition of n-heptane and CO with the operation parameters such as the type of catalyst, reaction temperature, and discharge power. From several sets of experiments, it was found that the decomposition efficiency of n-heptane mainly depended on the specific input energy rather than the reactor temperature, whereas the oxidation of CO on both the energy density and the reaction temperature. The results conducted over several metal oxide catalysts exhibited that the decomposition efficiency of n-heptane was in the order: $Pd/{\gamma}-Al_2O_3$ > $Ru/{\gamma}-Al_2O_3{\approx}Ag/{\gamma}-Al_2O_3$. Especially, $Pd/{\gamma}-Al_2O_3$ catalyst did hardly generate CO as a byproduct during the decomposition of n-heptane under an appropriate condition, revealing $CO_2$ selectivity of nearly 100%. The CO oxidation efficiency was largely affected by the type of catalyst ($Pd/{\gamma}-Al_2O_3$ > $Ru/{\gamma}-Al_2O_3$ > $Ag/{\gamma}-Al_2O_3$). At temperatures below $180^{\circ}C$, the plasma-catalytic process was more effective in the oxidation of CO, while above $180^{\circ}C$, the catalytic process resulted in slightly higher CO oxidation efficiency.

• Journal of Soil and Groundwater Environment
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• v.16 no.2
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• pp.52-60
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• 2011

Although facilities for the passive treatment of AMD (Acid Mine Drainage) are currently operating in Korea, their removal efficiency for heavy metals is relatively low in average (only 80%). Passive treatment system is composed of oxidation tank, SAPS (Successive Alkalinity Producing System), and wetland. In the treatment system adopted in korea, SAPS (Successive Alkalinity Producing System) plays a major role to remove about 65% of heavy metals through a precipitation. However, the efficiency of SAPS is limited due to the use of mushroom compost (MC) as a organic material and of limestone as a neutralizer. Therefore, this research was performed to search for alternative organic materials through the field test. We tested two types of mixed organic materials: 1) cow manure and spent oak (herein, CO) and 2) cow manure and sawdust (herein, CS). For comparison mushroom compost (herein, MC) was also tested. The result showed that the average Fe removal efficiency was 91.38% with CO, 85.19% with CS, and 91.58% with MC. Thus, CO can be effectively used as an alternative of MC in the SAPS system for heavy metals removal.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1297-1302
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• 2012

The interaction between carbon monoxide (CO) and a cobalt-salen complex (Co(salen)) was studied and applied to detect CO. The metal complex doped PEDOT:PSS film exhibited good sensitivity to CO and differentiate CO from other gases. The response of the composite to CO was reversible (RSD < 5%) change in resistance upon removal of CO gas from the test chamber. The effects of adding Co(salen) in the probe film on the response of the sensor were investigated using AFM, XPS, and FT-IR spectroscopy. The sensitivity of the sensor increased as the Co(salen) concentration enhanced as it increased from 0.0 to 1.5 wt. %, where the highest sensitivity ($%{\Delta}R/R_o$) of $-25.0{\pm}0.05%$ was achieved with 1.0 wt. % Co(salen). The sensor containing probe exhibited a linear response ($R^2$ = 0.983) in the range of 0.5 to 10.0% CO (v/v) $N_2$, and the detection limit was 1.74% CO (v/v) in $N_2$.

• The Journal of Advanced Prosthodontics
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• v.8 no.2
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• pp.110-115
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• 2016

PURPOSE. The purpose of this study was to compare the removal torques of a chemically modified SLActive implant and a blasted, laser-treated (BLT) implant, which were soaked in saline for 2 weeks after their surface modifications. The removal torques of the two implants were measured 4 weeks after their implantation into the bone defect area in rabbit tibias with concentrated growth factor (CGF) application. MATERIALS AND METHODS. To make artificial bone defects in the cortical layers of both tibias, an 8-mm diameter trephine bur was used. Then, prepared CGF was applied to the bony defect of the left tibia, and the bony defect of the right tibia was left unfilled. Four weeks later, the surgical sites of 16 rabbits were re-exposed. For 8 rabbits, the SLActive implants (Straumann, Switzerland) were inserted in the left tibia, and the BLT implants (CSM implant, Daegu, Korea) were inserted in the right tibia. For other rabbits, the BLT implants were inserted in the left tibia, and the SLActive implants were inserted in the right. Four weeks afger the insertion, torque removal was measured from 4 rabbits exterminated via $CO_2$ inhalation. RESULTS. No significant difference was observed between removal torques of the BLT implant and the SLActive implant (P>.05). CONCLUSION. It was found that BLT surface modification exhibited excellent osseointegration. In addition, CGF application did not affect the insertion and removal torque of the implants.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.6
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• pp.395-408
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• 2023

This study presents a novel method for addressing the issue of high-concentration contaminants (ammonium, phosphate, antibiotics) in leachate arising from decomposing livestock carcasses. Antibiotics, developed to eliminate microorganisms, often have low biodegradability and can persist in the ecosystem. This research proposes design elements to prevent contamination spread from carcass burial sites. The adsorbents used were low-grade charcoal (an industrial by-product), Alum-based Adsorbent (ABA), and Zeolite, a natural substance. These effectively removed the main leachate contaminants: low-grade charcoal for antibiotics (initial concentration 1.05 mg/L, removal rate 73.4%), ABA for phosphate (initial concentration 2.53 mg/L, removal rate 99.9%), and zeolite for ammonium (initial concentration 38.92 mg/L, removal rate 100.0%). The optimal mix ratio for purifying leachate is 1:1:10 of low-grade charcoal, ABA, and zeolite. The average adsorbent usage per burial site was 1,800 kg, costing KRW 2,000,000 per ton. The cost for the minimum leachate volume (about 12.4 m³) per site is KRW 2,880,000, and for the maximum volume (about 19.7 m³) is KRW 4,620,000. These findings contribute to resolving issues related to livestock carcass burial sites and suggest post-management strategies by advocating for the effective use of adsorbents in leachate purification.

• Journal of Environmental Science International
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• v.22 no.9
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• pp.1097-1103
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• 2013

Tetrafluoromethane($CF_4$) have been widely used as etching and chemical vapor deposition gases for semiconductor manufacturing processes. $CF_4$ decomposition efficiency using microwave system was carried out as a function of the microwave power, the reaction temperature, and the quantity of $Al_2O_3$ addition. High reaction temperature and addition of $Al_2O_3$ increased the $CF_4$ removal efficiencies and the $CO_2/CF_4$ ratio. When the SA30 (SiC+30wt%$Al_2O_3$) and SA50 (SiC+50wt%$Al_2O_3$) were used, complete $CF_4$ removal was achieved at $1000^{\circ}C$. The $CF_4$ was reacted with $Al_2O_3$ and by-products such as $CO_2/CF_4$ and $AlF_3$ were produced. Significant amount of by-product such as $AlF_3$ was identified by X-ray powder diffraction analysis. It also showed that the ${\gamma}-Al_2O_3$ was transformed to ${\alpha}-Al_2O_3$ after microwave thermal reaction.

• Laser Solutions
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• v.12 no.2
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• pp.7-10
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• 2009

In this paper, we study experimentally the local polishing of $SiO_2$ surface using the $CO_2$ laser. For laser local polishing, we polished to remove the grooves or to be reformed the surface of grooves after forming the grooves on the material surface. We measured the reflectance, transmittance, and beam profile in order to measure the roughness of polished surface. The Atom Force Microscope (AFM) is used to measure roughness of local polishing surface. We can predict that the laser polishing contribute to the removal of generated debris and surface roughness on the micro processing.

• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.129-136
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• 2003

Numerical study with momentum-balanced boundary conditions has been conducted to grasp chemical effects of added $CO_{2}$ and $H_{2}O$ to fuel- and oxidizer-sides on flame structure and NO emission behavior in $CH_{4}$/Air counterflow diffusion flames. The dilution with $H_{2}O$ results in significantly higher flame temperatures and NO emission, but dilution with $CO_{2}$ has much more chemical effects than that with $H_{2}O$. Maximum reaction rate of principal chain branching reaction due to chemical effects decreases with added $CO_{2}$. but increases with added $H_{2}O$. The NO emission behavior is closely related to the production rate of OH, CH and N. The OH radical production rate increases with added $H_{2}O$ but those of CH, N decrease. On the other hand the production rates of OR CH and N decrease with added $CO_{2}$. It is found that NO emission behavior is considerably affected by chemical effects of added $CO_{2}$ and $H_{2}O$.