• Journal of Korean Society for Atmospheric Environment
• /
• 제24권E2호
• /
• pp.83-91
• /
• 2008

This work investigated the methodology to simultaneously optimize the ozone and relative humidity composition for the $NO_x$ degradation using soil biofilter. Experiments were made as a function of inlet ozone concentration ($0{\sim}1,770\;ppb$) and relative humidity ($38{\sim}81%$). Factorial design ($2^2+3$) and response surface methodology by central composite designs were used to examine the role of two factors and optimal response condition on $NO_x$ degradation. It was found that a second-order response surface model can properly interpret the experimental data with an $R^2$-value of 0.9730 and F-value of 71.83, based on which the maximum $NO_x$ degradation was predicted up to 92.8% within our experimental conditions.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
• /
• pp.128-131
• /
• 2001

We evaluated natural attenuation of petroleum hydrocarbons in a shallow aquifer using a modeling study. The studied shallow aquifer was severely contaminated with petroleum hydrocarbons, especially toluene, ethylbenzene and xylenes (i.e, TEX). The exact spill history was not known. Therefor we used a contaminant level in May 1999 (the first sampling date of our integrated study) as an initial contaminant concentration. we calibrated required transport parameters using the contamination levels obtained from groundwater analyses in September of 1999. For fate and transport of the petroleum contaminants, five case 2 with sorption and degradation. case 3 with sorption and degradation (half decay constant compared with case 2), case 4 with degradation but no sorption, and case 5 with sorption but no degradation. For sorption and degradation, a linear sorption isotherm and first order irreversible decay was assumed, respectively and no additional contamination source to groundwater is also assumed.

• 한국전기전자재료학회논문지
• /
• 제17권6호
• /
• pp.586-591
• /
• 2004

We studied the dependence of hot-tarrier-induced degradation characteristics on nitrogen concentration in NO(Nitrided-Oxide) gate of nMOS, under ac and dc stresses. The $\Delta$V$_{t}$ and $\Delta$G$_{m}$ dependence of nitrogen concentration were observed, We observed that device degradation was suppressed significantly when the nitrogen concentration in the gate was increased. Compared to $N_2$O oxynitride, NO oxynitride gate devices show a smaller sensitivity to ac stress frequency. Results suggest that the improved at-hot carrier immunity of the device with NO gate may be due to the significantly suppressed interface state generation and neutral trap generation during stress.ess.

• 한국환경과학회지
• /
• 제16권11호
• /
• pp.1247-1255
• /
• 2007

Soil biofiltration is an environmentally-sound technology for elimination of VOCs, odorous and $NO_X$ compounds from a low concentration, high volume waste gas streams because of its simplicity and cost-effectiveness. This study investigated the optimal mixture fraction of briquet ash, compost, soil and loess for $NO_X$ degradation. Extreme vertices design was used to examine the role of four components on $NO_X$ degradation. Under our experimental conditions, 74.5% of $NO_X$ degradation was observed, using a model mixture(25% briquet ash, 10% compost, 30% soil and 40% loess) containing 100 ppb of NO. It was shown that experimental design analysis could allow selecting optimal conditions in such biodegradation processes in this study.

• Asian-Australasian Journal of Animal Sciences
• /
• 제16권3호
• /
• pp.389-393
• /
• 2003

Present study investigate the effect of enzyme supplementation, methods (applied to rumen or enzyme treated diet) compared with no enzyme diet, on rumen fermentation and apparent nutrient digestibility in a $3{\times}3$ Latin square design with three rumen cannulated Korean Native goats. In situ rumen degradation kinetics was studied in three rumen cannulated Holstein steers. Three diets were, no enzyme, 1% enzyme in rumen and 1% enzyme in diet. The enzyme was sprayed onto forage, and the forage: concentrate ratio was 30:70. Degradation kinetics was studied with three enzyme levels (0, 1 and 2%, w/w) and four pre-treatment times (0, 1, 12 and 24 h). Results suggested that enzyme application method did not affect rumen fermentation, ruminal enzyme activity and total tract apparent digestibility. Nutrient degradation rate and effective degradability of DM, NDF and ADF increased with increasing enzyme level and pre-treatment times. Degradation of nutrients was affected by enzymes levels or pre-treatment times. Therefore, it is probable that the improved degradation may be due to the supplemented exogenous hydrolytic enzymes under a certain condition.

• 한국환경농학회지
• /
• 제6권2호
• /
• pp.73-76
• /
• 1987

들깨 수원(水原) 8호(號)(Perilla frutescens Suwon No. 8)에 $SO_2$를 접촉(接觸)시켰을 때 일어나는 광합성색소(光合成色素)의 변화(變化)에 대(對)한 $SO_2$농도(濃度), 접촉시간(接觸時間), 광,(光) 활성산소(活性酸素)와 무기(無機) $SO_3\;^{-2}$의 영향(影響)을 관찰분석(觀察分析)한 결과(結果)는 다음과 같다. 1. $SO_2$농도(濃度)가 높아지고 접촉시간(接觸時間)이 길어질수록 피해(被害)가 심해저 엽록소(葉綠素)의 파괴(破壞)도 많았다. 2. $SO_2$ gas접촉에 의하여 엽록소(葉綠素)a가 엽록소(葉綠素)b 보다 쉽게 분해(分解)되었으며 또한 carotinoid도 엽록소(葉綠素)b보다 쉽게 분해(分解)되는 것으로 추정된다. 3. 들깨의 $SO_2$에 의한 엽록소파괴(葉綠素破壞)는 $SO_2$에 의한 직접적(直接的)인 영향(影響)으로 파악되었고, 이 때에 광(光)이 필수적(必須的)으로 필요하며, 물이 광분해(光分解)로 생성(生成)되는 $O_2^-$가 $SO_2$와 함께 엽록소분해(葉綠素分解)에 중심적(中心的)인 역할을 하는 물질이었다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제7권1호
• /
• pp.41-48
• /
• 1994

This experiment was carried out in order to evaluate the chemical composition and rumen degradation characteristics of Italian ryegrass harvested at three different growth stages, i,e. pre-blooming, early-blooming and late-blooming. Degradation values were obtained by incubation of the samples using the nylon bag technique on the rumen of sheep fed a normal diet (Timothy hay with 200 g/d concentrate per head) for 12, 24, 36, 48 and 72 hours, respectively. Neutral detergent fiver (NDF) content was highest at late-blooming (64.4%) while no difference was found among the pre-blooming and early-blooming (49.4% vs 48.3%). However, acid detergent fiber (ADF) content markedly increased from 30.0% at pre-blooming to 35.4% and 46.4% at early-blooming and late-blooming, respectively. Lignin and silica contents also increased as advancing maturity of the grass, Rumen degradation of dry matter (DM) significantly reduced (p < 0.05) as advancing maturity of the grass. Ruman degradation cellulose and ADF at pre-blooming were significantly higher (p < 0.05) than those of early-blooming and late-blooming. However, no significant differences were observed among the early-blooming and late-blooming. With advancing maturity, rumen degradation of NDF and hemicellulose significantly reduced (p < 0.05) at the incubation times.

• 한국환경농학회지
• /
• 제26권1호
• /
• pp.55-61
• /
• 2007

본 연구에서는 ZVI 종류[Peerless unannealed(PU), Peerless annealed(PA)]별 처리농도(1, 5%, w/v), 초기 metolachlor 농도(200, 1000 mg/l) 및 온도(15, 25, $35^{\circ}C$)가 metolachlor의 분해에 미치는 kinetics를 평가하였다. ZVI에 의한 metolachlor의 분해는 first order kinetics모델로 설명할 수 있었다. ZVI의 처리 농도가 증가할수록 metolachlor 의 분해속도가 빨랐다. 5%(w/v)의 PU와 PA ZVI를 처리시 metolachlor의 분해 반감기는 각각 9.9와 6.5 h 이었고 metolachlor는 72 및 48 h 에 모두 분해되었다. metolachlor의 분해상수(k)는 초기 metolachlor 농도가 낮을 때 컸다. ZVI에 의한 metolachlor의 분해는 온도가 높을수록 증가되었고 15, 25, $35^{\circ}C$에서 metolachlor의 분해상수(k)는 각각 0.0805, 0.1017, 0.3116 /h 이었다. ZVI에 의한 metolachlor 분해 시 2종류의 분해산물이 동정되었는데 이는 탈염소화된 metolachlor$(C_{13}H_{18}NO)$, 탈염소화-탈알킬화된 metolachlor$(C_{12}H_{17}NO)$이었다. PA ZVI가 PU ZVI 보다 metolachlor를 분해하는데 효율적임을 알 수 있었다. ZVI는 탈염소화기작에 의해 metolachlor를 분해함을 알 수 있었다.

• KSBB Journal
• /
• 제14권2호
• /
• pp.136-140
• /
• 1999

Characteristics of organic acid degradation by isolated yeast strain was investigated. Optimum initial pH was 5. Increase in cell mass was proportional to the decrease in organic acid degradation. Also no accumulation of byproduct was observed during degradation. Acetic acid degraded fast, followed by butyric acid and propionic acid in order. No significant substrate inhibition was observed up to 12 g/L of acetic acid 7 g/L of propionic acid, respectively. However, inhibition of butyric acid was significant above 4 g/L. Cell mass yield was 0.2-0.4 g cell/g acids and decreased at high decreased at high organic acid concentration. 95% of organic acid (7.5 g/L), corresponding to 13,000 ppm, was degraded in 30-40 hours.

• 한국식품영양학회지
• /
• 제23권4호
• /
• pp.542-548
• /
• 2010

This study was conducted to investigate the effects of Acanthopanax senticosus extracts(ASE) on alcohol administered mice. The administration of Acanthopanax senticosus extracts(60 mg/kg) had beneficial actions toward alcohol degradation in acute alcohol treated mice. In the acute alcohol degradation experiment, serum alcohol concentration were lower 3 and 6 hours after taking ethanol(5 g/kg) in ASE treated mice. The oral administration of ASE showed decreased gastric mucous membrane damage produced in ethanol treated mice. In addition, intraperitoneal(i.p.) administration of ASE showed antiinflammatory effects in inhibition tests of vascular permeability produced by acetic acid. ASE also reduced concentrations of nitric oxide(NO), tumor necrosis alpha(TNF)-${\alpha}$ and interleukin(IL)-6 in macrophages that were activated by LPS. These results demonstrate that Acanthopanax senticosus extracts possesses the potential to stimulate alcohol degradation and inhibit inflammatory effects in mice.