• Journal of Korean Society of Water and Wastewater
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• v.14 no.2
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• pp.157-163
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• 2000

An experimental study was conducted to evaluate the treatment efficiency of paper-mill wastewater using pure oxygen activated sludge process. Effects of hydraulic retention time (HRT) and organic loading on process performance and kinetics were investigated. The raw paper-mill wastewater(BOD concentration ${\leq}500mg/L$) and the effluent from dissolved air flotation(DAF) treatment(BOD concentration ${\geq}500mg/L$) were used as influent for pure oxygen activated sludge process. Average BOD removal efficiencies were above 89.3% under 6hours or longer of HRT, while under 3hours of HRT they decreased to about 82%. With the effluent from DAF process, the half saturation constants($K_S$) and the maximum specific substrate removal rate($K_{max}$) were 85 mg/L and 2.25 L/day, respectively. However, with the raw paper-mill wastewater, both $K_S$ and $K_{max}$ increased to 156 mg/L and 3.84 L/day, respectively. The microbial yield coefficient(Y) and the decay coefficient($K_d$) were 0.46 gVSS/gBOD and 0.03 L/day, respectively, with effluent from DAF process. While, Y and $K_d$ were 0.24 gVSS/gBOD and 0.035 L/day, respectively, with the raw paper-mill wastewater.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.296-305
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• 1996

Chemical characteristics of paper sludge, degradation of the sludge in soil and $CO_2$ generation, and changes of nitrogen and heavy metals in soil treated with the sludge were investigated. The results obtained was summarized as follows: 1. Degradation rate of paper sludge in soil was 19% at room temperature, and 28% at $incubation(30^{\circ}C)$ temperature after 12-weeks treatment. 2. T-C, T-N and the C/N ratio of the sludge in soil at room temperature were 15.5%, 0.22% and 71 respectively, and 14.5%, 0.24% and 60, respectively, at $incubation(30^{\circ}C)$ temperature after 12-week treatment. 3. $CO_2$ genaration in soil treated with 1%, 3% and 5% of the sludge was 247mg/100g, 334mg/100g and 458mg/100g, respectively, at room temperature, and 385mg/100g, 550mg/100g and 618mg/100g, respectively, at incubation temperature after 12 weeks treatment. 4. Mineralization ratio of organic nitrogen in soil treated with 1%, 3% and 5% of the sludge was 8.7%, 13.4% and 16.2%, respectively, at $incubation(30^{\circ}C)$ temperature after 12-weeks treatment. 5. The amounts of DTPA-extractable Cu, Cd, Zn, Pb, and Cr in Soil treated with paper sludge were $0.7{\sim}2.2$, $0.1{\sim}0.17$, $1.4{\sim}2.8$, $1.4{\sim}2.8$, and $0{\sim}0.7mg/kg$, respectively. Mean while, those of $HNO_3$ extractable Cu, Cd, Zn, Pb, and Cr were $7.9{\sim}10.0$, $0.6{\sim}0.9$, $17.6{\sim}34.4$, $14.7{\sim}18.5$, and $5.8{\sim}9.0mg/kg$, respectively.

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.608-614
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• 2012

The effluent limitation of industrial wastewater is based on uniform regulatory criteria for effluent discharge facilities of all in Korea. But, an individual effluent limitation on each effluent discharge facility is widely applicable for regulation of industrial wastewater in US.EPA. To decide an individual effluent limitation, TBEL (Technology-based effluent limitation) and WQBEL (Water quality-based effluent limitation) are used. TBEL is based on the capability of a treatment technology to reduce the pollutants. WQBEL is based on ambient water quality standards. In this study, TBEL were derived for the pulp, paper and paper board manufacturing based on best practicable control technology currently available. It was suggested that effluent limitations were $BOD_5$ 4.7 mg/L, $COD_{Mn}$ 44.3 mg/L, SS 13.2 mg/L, TN 1.4 mg/L, TP 0.15 mg/L and best practicable control technology currently available (BPT) was neutralization, activated sludge treatment and coagulation and sedimentation for the pulp, paper and paper board manufacturing.

• Journal of dental hygiene science
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• v.3 no.1
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• pp.39-44
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• 2003

This study was to investigate the antibacterial effect of Schizandrae fructus and Evodiae fructus extracts on S. mutans growth. The antibacterial effect of these extracts on S. mutans was good at Schizandrae fructus extract than the Evodiae fructus extract. The antibacterial activities of these extracts were measured 8.5 mm and 6.5 mm at 20 mg/ml concentration, respectively. The growth of S. mutans in control medium was the highest at 8 hrs, while the media of Schizandrae fructus and Evodiae fructus extracts added-medium(2 mg/ml) showed maximum growth at 16hrs. The pH values of the control medium was 5.08 at 8 hrs, but the media supplemented with Schizandrae fructus and Evodiae fructus extracts were 6.00, and 5.36 at 8 hrs, respectively. The amounts of total carbohydrate for the control media was 0.81 mg/ml at 8 hrs, but the media supplemented with Schizandrae and Evodiae fructus extracts were 1.32 mg/ml and 1.88 mg/ml at 8 hrs, respectively. In the change of culture medium proteins, the control culture broth and cultures supplemented with Schizandrae fructus and Evodiae fructus extracts were 8.39 mg/ml, 8.59 mg/ml and 9.97 mg/ml at 8 hrs, respectively. The S. mutans polysaccharide contents of the control medium and the media supplemented with Schizandrae and Evodiae fructus extracts were 300 mg/100 ml, 240 mg/100 ml and 280 mg/100 ml at 8 hrs, respectively.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_3
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• pp.1269-1278
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• 2023

This paper presents an operational technique that can secure the stability of DC-Grid centering on MG operated based on ESS in multiple MG where three DC-based microgrid(MG) are interconnected. MG1(PV 600kWp, ESS 1.5MWh) has an 830Vdc grid voltage, MG2(PV 300kWp, ESS 1.1MWh) and MG3(PV 100kWp, ESS 500kWh) are DC-based MG with a 750Vdc grid voltage, and MG1 and MG2, 3 are linked by separate DC/DC converters (BTB). In order to keep different grid voltages stable, the power transmission capacity between MG1 and two MG(MG2, MG3) connected with an independent BTB converter was adjusted to secure the overall stability of the system, and this was verified by confirming that the surplus capacity of ESS was maintained in actual operation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1566-1571
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• 2009

The discharge electrodes in ac PDP are coated with dielectric layer, and transparent MgO thin films are deposited on the dielectric layer. The main role of the MgO thin films in ac PDP is to protect the dielectric layer from sputtering by ion bombardment in the glow-discharge plasma. An additional important role of the MgO thin film is the high secondary electron emission coefficient which leads the low firing voltage and low cost of the PDP. In this paper, we investigated the relations of the crystal orientation about deposition thickness, deposition rate, temperature of substrate, and distance between the MgO tablet and the substrate. Additionally, we investigated the discharge characteristics of the AC PDP using nano-powder MgO tablet

• YAKHAK HOEJI
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• v.31 no.4
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• pp.204-212
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• 1987

Rifampicin is an indispensable drug along with isoniazid for the control of tuberculosis and is usually prescribed as the combination of rifampicin and isoniazid. This paper is attemtped to investigate the interaction of rifampicin and isoniazid. Isoniazid was administered orally at a dose of 30mg/kg of rabbits pretreated with rifampicin 7.5mg/kg, 15mg/kg, and 30mg/kg, respectively twice daily for 9 days. The results are as follows: The blood level and relative bioavailability of isoniazid were decreased significantly (p<0.05) by rifampicin at a dose of 15mg/kg and 30mg/kg. The renal clearance of total isoniazid and ratio of its metabolites to isoniazid were increased significantly (p<0.05) by rifampicin at a dose of 15mg/kg and 30mg/kg. It seemed to be due to enzyme induction by rifampicin. Elimination rate constant ($\beta$) of isoniazid was increased and half life ($t_{1/2$\beta}$) was decreased by rifampicin pretreatment. Dosage regimen of isoniazid after long term administration of rifampicin should be adjusted carefully.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.10
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• pp.447-450
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• 2003

This paper presents a process optimization of antireflection (AR) coating on crystalline Si solar cells. Theoretical and experimental investigations were performed on a double-layer AR (DLAR) coating of MgF$_2$/CeO$_2$. We investigated CeO$_2$ films as an AR layer because they have a proper refractive index of 2.46 and demonstrate the same lattice constant as Si substrate. RF sputter grown CeO$_2$ film showed strong dependence on a deposition temperature. The CeO$_2$ deposited at 40$0^{\circ}C$ exhibited a strong (111) preferred orientation and the lowest surface roughness of 6.87 $\AA$. Refractive index of MgF$_2$ film was measured as 1.386 for the most of growth temperature. An optimized DLAR coating showed a reflectance as low as 2.04% in the wavelengths ranged from 0.4${\mu}{\textrm}{m}$ to 1.1${\mu}{\textrm}{m}$. We achieved the efficiencies of solar cells greater than 15% with 3.12% improvement with DLAR coatings. Further details on MgF$_2$, CeO$_2$ films, and cell fabrication parameters are presented in this paper.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.593-596
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• 1999

This paper presents a process optimization of antireflectiun (AR) coating on crystalline Si solar cells. Theoretical and experimental investigations were performed on a doble-layer AR(DLAR) coating of MgF$_2$/CeO$_2$, We investigated CeO$_2$ films as an All layer because they hale a proper refractive index of 2.46 and demonstrate the same lattice constant as Si substrate. RF sputter grown CeO$_2$ film showed strong dependence on a deposition temperature. The CeO$_2$ film deposited at 400 $^{\circ}C$ exhibited a strong (111) preferred orientation and the lowest surface roughness of 6.87 $\AA$. Refractive index of MgF$_2$ film was measured as 1.386 for the most of growth temperature. An optimized DLAR coating showed a reflectance as low as 2.04 % in the wavelengths ranged from 0.4 7m to 1.1 7m. We achieved the efficiencies of solar cells greater than 15% with 3.12 % improvement with DLAR coatings . Further details on MgF$_2$, CeO$_2$ films, and cell fabrication Parameters are presented in this paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.22-27
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• 2012

Correct and fast detection of a micro-grid (MG) islanding is essential to the MG since operation, control and protection of the MG depend on an operating mode i.e., an interconnected mode or an islanding mode. When islanding occurs, the frequency of the point of common coupling (PCC) is not the nominal frequency during the transient state owing to the frequency rise or drop of generators in the MG. Thus, the active and reactive power calculated by the frequency domain based method such as Fourier Transform might contain some errors. This paper proposes an islanding detection algorithm for the MG based on the instantaneous active and reactive powers delivered to the dedicated line in the time domain. During the islanding mode, the instantaneous active and reactive powers delivered to the dedicated line are constants, which depend on the voltage of the PCC and the impedance of the dedicated line. In this paper, the instantaneous active and reactive powers are calculated in the time domain and used to detect islanding. The performance of the proposed algorithm is verified under various scenarios including islanding conditions, fault conditions and load variation using the PSCAD/EMTDC simulator. The results indicate that the algorithm successfully detects islanding for the MG.