• 한국물환경학회지
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• 제28권3호
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• pp.401-408
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• 2012

High-voltage dielectric discharges are an emerging technique in environmental pollutant degradation, which that are characterized by the production of hydroxyl radicals as the primary degradation species. The initiation and propagation of the electrical discharges depends on several physical, chemical, and electrical parameters such as 1st and 2nd voltage of power, gas supply, conductivity and pH. These parameters also influence the physical and chemical characteristics of the discharges, including the production of reactive species such as OH, $H_2O_2$ and $O_3$. The experimental results showed that the optimum 1st voltage and air flow rate for RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation were 160 V (2nd voltage of is 15 kV) and 4 L/min, respectively. As the increased of the 2nd voltage (4 kV to 15 kV), RNO degradation, $H_2O_2$ and $O_3$ generation were increased. The conductivity of the solution was not influencing the RNO degradation and $H_2O_2$ and $O_3$ generation. The effects pH was not high on RNO degradation. However, the lower pH and the conductivity, the higher $H_2O_2$ and $O_3$ generation were observed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.495-496
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• 2008

This paper describes the influence of Ultra-violet irradiation on time to tracking resistance of epoxy insulating materials by use of the inclined plane test. And, the influence of surface degradation was evaluated through several method such as measurement of contact angle, surface roughness, using a scanning electron microscopy. As the 1000 hours of the surface degradation with UV-CON, the flashover time decreases at different rates depending on epoxy resin and silicone rubber specimen. As the duration of the surface degradation with UV-CON is prolonged, the contact angle of epoxy resin decreases at the rate of degradation time, while that of silicone rubber was not exchanged. It is assumed that this phenomenon is related to the decrease in hydrophobicity of the surface of the materials. Also, as to epoxy resin, the decrease of hydrophobicity due to surface degradation with UV-CON is greater than that resulting from surface degradation with WOM. The UV radiation produced chalking and crazing on the surface of the insulating materials specimen.

• 한국환경보건학회지
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• 제22권2호
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• pp.90-95
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• 1996

This study was performed to calculate the degration rate coefficient, operating parameters to meet the effluent standards, and the temperature adjustment coefficients to each parameter of pollution by seasonal variation of concentration and temperature of influent in livestock wastewater treatment by sequencing batch reactor process in field scale. The followings are the conclusions that were derived from this study. 1. In the field, temperature of livestock wastewater in reactor was 20.3$\circ$C in summer and 6.0$\circ$C in winter. The ratio of BOD:TKN: T-P in influent was 100:80:7. BOD loadings in winter and spring were 0.26 and 0.43 kg $BOD/m^3$ day, respectively. Those in summer and fall were 0.25 and 0.13 kg $BOD/m^3$ day, respectively. 2. The degradation rate coefficient for TKN was larger in summer and fall in which temperature was high than that in which temperature was high than that in winter and spring in which concentration was high. On the contrary, the phosphorus uptake rate was larger in winter and spring than that in summer and fall. 3. The hydraulic retention time in winter and spring was longer than that in summer and fall. Especially, in order to meet the standard for TKN of 120 mg/l in winter in which temperature of wastewater was 6.0$\circ$C, as the MLSS concentration was increased from 4, 000 to 7, 000 mg/l, the hydraulic retention time was increased from 212 to 121 hours. But, in order to shorten that less than 121 hours for the economical wastewater treatment, countermeasure to increase temperature of wastewater in the reactor should be considered. 4. the temperature adjustment coefficients for BOD, $COD_{Mn}$, TKN and T-P were 1.0241, 1.0225, 1.0541 and 1.0495, respectively. Namely, the treatment of TKN was most sensitively affected by temperature. For the purpose of the effective removal of nitrogen and phosphorus which are sensitive to temperature, it is necessary to keep the temperature of livestock wastewater more than 20$\circ$C which is the temperature of it in summer.

• 한국환경과학회지
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• 제9권2호
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• pp.151-158
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• 2000

Considerable interest has been shown in recent years towards utilizing $TiO_2$ particles as a photocatalyst in the degradation of harmful organic contaminants. In this study, photocatalytic degradation of diazinon which is extensively used as a pesticide in the agriculture field, has been investigated with UV-illuminated $TiO_2$ weight, UV wavelength, pH of the solution. Photodegradation rate increased with decreasing initial concentration of diazinon and with increasing pH of the solution. Photodegradation rate increased with increasing $TiO_2$ weight, but was nearly the same at $TiO_2$ weight of 1g/$\ell$, 2 g/$\ell$, i.e., for initial diazinon concentratin of 5 mg/$\ell$. UV wavelength affecting on the degradation rate of diazinon decreased in the order of 254 nm>312 nm> 365 nm. For $TiO_2$ weight of 1 g/$\ell$and initial diazinon concentration of 5 mg/$\ell$, the photodegradation removal of diazinon was 100% after 130 min in the case of 254 nm, but 95% in the case of 312 nm, and 84% in the case of 365nm, after 180 min. The photodegradation of diazinon followed a first order or a pseudo - first order reaction rate. For initial diazinon concentration of 5 mg/$\ell$, the rate constants(k) in UV and $TiO_2$(1 g/$\ell$)/UV system were $0.006 min^{-1} and 0.0252 min^{-1} at 254 nm, 0.0055 min^{-1} and 0.0104 min^{-1} at 312 nm, and 0.004 min^{-1}$ at 365 nm respectively.

• 한국환경과학회지
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• 제33권2호
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• pp.131-138
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• 2024

The effect of magnetite particles on the anaerobic digestion (AD) of furfural wastewater was investigated using sequential anaerobic batch tests. The batch tests with four 500 mL anaerobic bioreactors were performed under two conditions: FC treatment for AD of furfural without magnetite particles, and FM treatment for AD of furfural with magnetite particles. The FC bioreactors showed a decreasing methane production rate (MPR) across the sequential batches, with a final batch MPR of 11.3 ± 0.4 mL CH₄/L/d, indicating the need for a methanogenesis enhancer to achieve high-rate AD of furfural. Conversely, FM bioreactors exhibited significantly higher MPR, exceeding FC values by 4-196%, with a final batch MPR of 33.5 ± 0.1 mL CH₄/L/d, which was about three times higher than FC. Additionally, FM bioreactors had faster degradation rates of furfural, valeric acid, and acetic acid compared to FC, with values exceeding those in PC by 3.0, 1.14, and 2.8 times, respectively. These results demonstrate that magnetite particles can enhance the AD of furfural not only by accelerating methanogenesis but also by accelerating the anaerobic degradation of furfural and its intermediates, such as volatile fatty acids. This study provides valuable insights for developing high-rate AD systems for furfural wastewater treatment.

• Journal of Animal Science and Technology
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• 제49권3호
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• pp.351-358
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• 2007

본 연구는 국내에서 사용되고 있는 몇 가지 단백질 원료사료를 사용하여 단백질 fraction과 in situ 단백질 분해율을 구한 다음 이들 사이에서의 상관관계를 살펴보고자 실시하였다. 원료사료는 대두박, 콘글루텐, 면실박, 카폭박 및 임자박이었다. 단백질 fraction은 CNCPS에서 제시하는 방법으로 구하였으며, in situ 단백질 분해율은 캐뉼라가 장착된 홀스타인 거세우 3두를 이용하여 반추위에서 원료사료를 4, 8, 12 및 24시간 배양하여 구하였다. 단백질 fraction 중 A fraction은 카폭박이 14.6%로 가장 높았고, 콘글루텐이 0.6%로 가장 낮았다(P<0.05). B1 fraction은 대두박이 8.27%로 가장 높았으며, B2 fraction은 대두박과 면실박이 74%로 가장 높았다. B3 fraction은 임자박이 40%로 다른 원료사료에 비교해 뚜렷하게 높았다. C fraction은 콘글루텐이 약 42.5%로 가장 높았다. In situ 조단백질 분해율은 대두박이 98%로 가장 높았고, 콘글루텐은 28%로 가장 낮았다. 단백질 fraction과 in situ 분해율 사이의 상관관계를 보면, 쉽게 용해되는 부분(A, B1 fraction vs a값) 사이에, in situ 조단백질 분해율과 소화가능한 단백질 fraction 사이에, 그리고 in situ 조단백질 분해율에서 a값을 제외한 값과 B2+B3 fraction 사이에는 상관관계가 높았다(P<0.01). 본 연구결과에 의하면, 단백질 fraction은 원료사료의 반추위내 분해율을 추정하는 데 이용될 수 있을 것으로 사료되며, 앞으로 더 정확한 평가를 위해서는 더 많은 원료사료에 대한 분석이 필요하다고 본다.

• Macromolecular Research
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• 제12권6호
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• pp.545-552
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• 2004

The long-term stability of sulfonic acid-containing polyimides has been investigated. The hydrolytic degradation of homopolyimide and the block copolyimide comprising $27\;mol\%$ of 2,2'-bis(trifluoromethyl)benzidine and $9\;mol\%$ of m-phenylenediamine (BTFMB27mPl0[7/(3+1)]), was quantified through viscosity measurements and FT-IR spectroscopic analyses. The viscosity decrease with respect to time and the degradation rate were similar. The degrees of degradation with respect to time under ambient conditions and at elevated temperature in water were monitored by FT-IR spectroscopy. A new absorption peak was observed at $1786\;cm^{-1},$ which we corresponds to the presence of anhydride end groups formed by hydrolytic scission of the imide rings.

• 한국생산제조학회지
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• 제9권2호
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• pp.45-51
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• 2000

This study proposes that analysis and evaluation method of time series ultrasonic signal using the chaotic feature extrac-tion for degradation extent. Features extracted from time series data using the chaotic time series signal analyze quantitatively material degradation extent. For this purpose analysis objective in this study if fractal dimension lyapunov exponent and strange attractor on hyperspace. The lyapunov exponent is a measure of the rate at which nearby trajectories in phase space diverge. Chaotic trajectories have at least one positive lyapunov exponent. The fractal dimension appears as a metric space such as the phase space trajectory of a dynamical syste, In experiment fractal(correlation) dimensions and lyapunov experiments showed values of mean 3.837-4.211 and 0.054-0.078 in case of degradation material The proposed chaotic feature extraction in this study can enhances ultrasonic pattern recognition results from degrada-tion signals.

• Current Photovoltaic Research
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• 제8권1호
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• pp.12-16
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• 2020

This study investigates the degradation characteristics of different material types of ethyl vinyl acetate (EVA) and polyolefin (POE) with combining transparent backsheet. To this end, we fabricated samples with structure of glass/encapsulant/transparent backsheet for each type of encapsulants, and shingled Si modules with the same structure. The samples were then subjected to accelerated test by storing under damp heat condition of 85℃ and 85% RH. As a result, encaplsulant discoloration was observed, which the transmittance of the samples with EVA decreased in a rapid rate than the samples with POE. The discoloration also affected a power degradation of the shingled modules with a reduction of current density, resulting that the module with EVA showed more drop on the efficiency than the modules with POE. Furthermore, corrosion of the soldered ribbon caused by acetic acid produced from the degraded EVA also contributed in fill factor reduction.

• 한국토양비료학회지
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• 제44권2호
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• pp.316-319
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• 2011

Biopiles which offer the potential for cost-effective treatment of contaminated soils are above-ground, engineered systems that use oxygen to stimulate the growth and reproduction of aerobic bacteria for degradation of the petroleum constituents adsorbed to soil in excavated soils. This technology involves heaping contaminated soils into piles and stimulating aerobic microbial activity within the soils through the aeration and/or addition of minerals, nutrients, and moisture. Inside the biopile, microbially mediated reactions by blowing or extracting air through the pipes can enhance degradation of the organic contaminants. The influence of a aeration system on the biopile performance was investigated. Air pressure made to compare the efficiency of suction in the pipes showed that there were slightly significant difference between the two piles in the total amount of TPH biodegradation. The normalised degradation rate was, however, considerably higher in the aeration system than in the normal system without aeration, suggesting that the vertical venting method may have improved the efficiency of the biological reactions in the pile.