• Economic and Environmental Geology
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• v.42 no.5
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• pp.445-455
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• 2009

Microbiological sulfate reduction is the transformation of sulfate to sulfide catalyzed by the activity of sulfate-reducing bacteria using sulfate as an electron acceptor. Low solubility of metal sulfides leads to precipitation of the sulfides in solution. The effects of microbiological sulfate reduction on in-situ precipitation of arsenic and copper were investigated for the heavy metal-contaminated soil around the Songcheon Au-Ag mine site. Total concentrations of As, Cu, and Pb were 1,311 mg/kg, 146 mg/kg, and 294 mg/kg, respectively, after aqua regia digestion. In batch-type experiments, indigenous sulfate-reducing bacteria rapidly decreased sulfate concentration and redox potential and led to substantial removal of dissolved As and Cu from solution. Optimal concentrations of carbon source and sulfate for effective microbial sulfate reduction were 0.2~0.5% (w/v) and 100~200 mg/L, respectively. More than 98% of injected As and Cu were removed in the effluents from both microbial and chemical columns designed for metal sulfides to be precipitated. However, after the injection of oxygen-rich solution, the microbial column showed the enhanced long-term stability of in-situ precipitated metals when compared with the chemical column which showed immediate increase in dissolved As and Cu due to oxidative dissolution of the sulfides. Black precipitates formed in the microbial column during the experiments and were identified as iron sulfide and copper sulfide. Arsenic was observed to be adsorbed on surface of iron sulfide precipitate.

• Journal of Lipid and Atherosclerosis
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• v.5 no.1
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• pp.61-77
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• 2016

Objective: This study aims to analyze cost-effectiveness of two most-commonly used statins from the perspective of the Korean national health system. Methods: The scope of the analysis included rosuvastatin (5 mg, 10 mg, and 20 mg) and atorvastatin (10 mg, 20 mg, 40 mg, and 80 mg). Effectiveness was defined as percentage (%) and absolute (mg/dL) reductions of low-density lipoprotein cholesterol (LDL-C) from the baseline. They were derived from published randomized controlled studies for rosuvastatin and atorvastatin. Effectiveness was defined as reductions in LDL-C levels per mg dose of the drugs. The annual direct medical costs including drug acquisition costs and monitoring costs over the one-year time horizon were calculated for each alternative. The average cost-effectiveness ratios (ACERs) and incremental cost-effectiveness ratios (ICERs) for each statin dose were calculated. Results: The ACERs for all doses of rosuvastatin (5 mg, 10 mg, and 20 mg) were lower than those for all doses of atorvastatin (10 mg, 20 mg, 40 mg, and 80 mg). Rosuvastatin 10 mg was the most cost-effective statin for LDL-C reduction. In cost-effectiveness analyses for corresponding doses of rosuvastatin and atorvastatin, rosuvastatin was the superior strategy which suggests both higher effectiveness and lower costs than atorvastatin. However, we have to consider this analysis is highly influenced by current price of statins in each market. Conclusion: For reduction of LDL-C levels in Korean patients with dyslipidemia, rosuvastatin 10mg is the most cost-effective statin in the current Korean market.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.3
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• pp.82-87
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• 2013

In this work, the 1L grade integrated metal DOC/DPF filter that can install in engine manifold position was developed to investigate the effect of platinum-coating amount of filter on the improvement of filter activation temperature and reduction of particulate matter (PM). This filter was installed in 2.9L CI engine which meets the EURO-4 emission regulation. Tests for PM reduction efficiency of filter were conducted under ND-13 mode with full-load test condition. It was revealed that the time to reach the activation temperature of metal filter ($280^{\circ}C$) was shorter as the amount of platinum-coating increased. This short activation time can be helpful for the reduction of CO and HC emissions during cold start condition. At the same time, PM reduced as the coating amount increased. The reduction percentage of $DOC_{40}$, $DOC_{20}$, and $DOC_0$ were 96.7% (2.34 mg/kW'h), 95.1% (3.47 mg/kW'h), and 94.5% (3.69 mg/kW'h) compared to previous result (71.4 mg/kW'h), respectively.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.3
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• pp.248-254
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• 2006

The promotion effects of noble metals upon the activity and reducibility in steam methane reforming over $Ni/MgAl_2O_4$ catalysts were investigated. While $Ni/MgAl_2O_4$ catalysts require the pre-reduction by $H_2$, the noble metal-added catalysts show high catalytic activities without pre-treatment. According to $CH_4$-TPR, the addition of noble metal makes the $Ni/MgAl_2O_4$ catalyst easily reducible. The reduction degree of NiO in the noble metal-added catalysts after using at $650^{\circ}C$ without pre-reduction was $15{\sim}20%$, and was lower than that in the $H_2$-reduced $Ni/MgAl_2O_4$ catalyst(reduction degree=27%). The enhancement of the catalytic activity over noble metal-added catalysts results from easier reducibility by addition of noble metal and the synergy effect between noble metal and Ni.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.911-916
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• 2005

In this study, variations of water quality, sediment size and contaminant substances are analyzed at upstream and downstream in sewer systems in order to evaluate the characteristics of wastewater transformation by physico-chemical and biological reactions. The differences of DOC concentration between up and down stream showed the range of $-5.8{\sim}18.6$ from the result of continuous measurement at up and down stream. About 8.4% of DOC concentration was reduced and reduction rate was 2.3 mg/L/km. SS reduction rate was measured by 5.5 mg/L/km, 0.22 mg/L/min from upstream to downstream, which was twice than DOC reduction rate. When pollution load reduction was evaluated considering infiltration/inflow effect, DOC load was eliminated from 1,230 ka/d to 1,167 kg/d by physi-chemical and biological reaction in a sewer and 7.8% of the SS in upstream station was reduced under dry weather condition. The results showed that the characteristics of transformation process of wastewater in sewer should be considered for design and operation of wastewater treatment plant.

• Membrane and Water Treatment
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• v.6 no.3
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• pp.189-203
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• 2015

Membrane biofouling impedes wide application of membrane bioreactor (MBR) for wastewater treatment. Recently, quorum sensing (QS) mechanisms are accounted for one of major mechanisms in biofouling of MBRs. In this study, vanillin was applied to investigate reduction of biofouling in MBRs. MBR sludge was analyzed to contain QS signal molecules by cross-feeding biosensor assay and HPLC. In addition, the inhibitory activity of vanillin against bacterial quorum sensing was verified using an indicator strain CV026. The vanillin doses greater than 125 mg/L to 100 mL of MBR sludge showed 25% reduction of biofilm formed on the membrane surfaces. Two MBRs, i.e., a typical MBR as a control and an MBR with vanillin, were operated. The TMP increases of the control MBR were more rapid compared to those of the MBR with the vanillin dose of 250 mg/L. The treatment efficiencies of the two MBRs on organic removal and MLSS were maintained relatively constant. Extracellular polymeric substance concentrations measured at the end of the MBR operation were 173 mg/g biocake for the control MBR and 119 mg/g biocake for the MBR with vanillin. Vanillin shows great potential as an anti-biofouling agent for MBRs without any interference on microbial activity for wastewater treatment.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.3
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• pp.35-40
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• 2021

In order to investigate the degree of solubilization of sewage sludge using sono-activated persulfate(UV/PP), VSS reduction rate, solubilization rate and extracellular polymeric substances were measured. Ultrasonic(US) and alkali·ultrasonic method using sodium hydroxide(US/SH) were compared. Under the persulfate·ultrasonic conditions, the VSS reduction rate and the solubilization rate increased to 27.6% and 58.9%, respectively. TB-EPS as Carbohydrate and Protein were extracted by 770 mg/L and 2,162 mg/L. Compared to the other methods, US and US/SH, the VSS reduction rate and solubilization rate were higher. And also, according to the TB-EPS values, cell wall destruction was more efficient.

• BMB Reports
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• v.47 no.10
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• pp.575-580
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• 2014

In this study, we investigate whether arsenite-induced DNA damage leads to p53-dependent premature senescence using human glioblastoma cells with p53-wild type (U87MG-neo) and p53 deficient (U87MG-E6). A dose dependent relationship between arsenite and reduced cell growth is demonstrated, as well as induced ${\gamma}H2AX$ foci formation in both U87MG-neo and U87MG-E6 cells at low concentrations of arsenite. Senescence was induced by arsenite with senescence-associated ${\beta}$-galactosidase staining. Dimethyl- and trimethyl-lysine 9 of histone H3 (H3DMK9 and H3TMK9) foci formation was accompanied by p21 accumulation only in U87MG-neo but not in U87MG-E6 cells. This suggests that arsenite induces premature senescence as a result of DNA damage with heterochromatin forming through a p53/p21 dependent pathway. p21 and p53 siRNA consistently decreased H3TMK9 foci formation in U87M G-neo but not in U87MG-E6 cells after arsenite treatment. Taken together, arsenite reduces cell growth independently of p53 and induces premature senescence via p53/p21-dependent pathway following DNA damage.

• Journal of Korea Foundry Society
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• v.32 no.1
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• pp.38-43
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• 2012

The effects of Mg and Cu amounts on the casting characteristics and tensile property of Al-Zn-Mg-Cu alloys were investigated for the development of high strength aluminium alloys for gravity mold casting. Increase of copper amounts in Al-6%Zn-3%Mgy% Cu alloys resulted in reduction of the fluidity of these alloys and had little effects on the tensile property of these alloys. Increase of magnesium amounts from 1.0wt% to 3.3wt% in Al-6%Zn-x%Mg-0.5%Cu alloys resulted in reduction of the elongation of these alloys from 12% to 3% and increase of the tensile strength of these alloys from 340MPa to 450MPa, but had little effects on the fluidity of these alloys.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.3
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• pp.415-423
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• 1996

Hydrogen reduction technique was used to form the nickel layer onto alumina powders in nickel sulfate solutions. The reduction rate and precipitation states of nickel ions were investigated at various experimental conditions such as hydrogen pressure, temperature, $PdCl_{2}$ addition, particle size, and so on. Uniformly nickel coated alumina composite powders were obtained at such condition as reduction temperature of $165^{\circ}C$, hydrogen pressure of 300 psi, and $PdCl_{2}$ amount of $2\;mg/\ell$.