• 한국대기환경학회지
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• 제24권2호
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• pp.143-152
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• 2008

This study investigates the variation and spatial distribution of nitrogen dioxide($NO_2$) concentrations measured with passive diffusive samplers at 40 curbside points in Daejeon. Average $NO_2$ concentration was $39.8{\pm}18.0\;ppb$ (n=1,127) and the significant difference in concentrations by regional groups (Dong-gu, Jung-gu, Seo-gu, Daedeok-gu, Yuseong-gu) was not observed. The frequency distribution of $NO_2$ concentration was found to be a normal distribution with the high frequency in the concentration range of 30 to 40 ppb (20 to 25%). Average $NO_2$ concentration measured during the rainy periods was lower than that measured during the non-rainy periods and the decrease of concentration by rainfall was about 16% (7 ppb). The variation of $NO_2$ concentrations measured by passive diffusive samplers during the sampling period was similar to that continuously measured at the air quality monitoring station.

• 한국환경복원기술학회지
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• 제8권6호
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• pp.59-68
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• 2005

This study was carried out to investigate soil properties, ordination, and vegetation of the coastal sand dune in Sinduri, Taean-Gun. 1. The Orobanche coerulescens and Ixeris repens that are a peculiar species were found in Sinduri coastal sand dune and the Salix purpurea var. japonica that is an endemic species of korea was found in that place. The plant communities was categorized into seven groups, such as Rosa rugosa community, Vitex rotundifolia communit, Carex kobomugi community, Imperata cylndrica var. koenigii community, Carex pumila community, Artemisia capillaris community, and Calamagrostis epigeios community. 2. The soil organic matter, total nitrogen, available phosphorous concentrations, and cation exchange capacity were lower in the study sites than in forest soil of seashore. There was little difference in soil exchangeable Ca, Mg, and K concentrations between in the study site and in the forest soil of seashore. The soil pH was ranged from 5.69 to 7.63. The soil texture in the study site was sand or loamy sand. 3. The results of the correlation between Sinduri coastal sand dune community and environmental factor are as follows; the soil pH was the most effect to the community distribution, and CEC, total nitrogen, soil organic matter, and the amount of silt in soil have some correlation with community distribution. 4. The results of the correlation between Sinduri coastal sand dune community and soil characteristics are as follows; the Calamagrostis epigeios community was found in area that have high soil moisture content; the Rosa rugosa community was found in area that have high soil CEC, organic matter concentration, and total nitrogen concentration, and low soil pH; the Vitex rotundifolia community, Carex kobomugi community, and Artemisia capillaris community were found in area that have low soil CEC, organic matter concentration, and total nitrogen concentration, and high soil pH; the Imperata cylndrica var. koenigii community and Carex pumila community were found in area that have medium soil CEC, organic matter concentration, total nitrogen concentration, and soil pH.

• The Korean Journal of Physiology
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• 제9권1호
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• pp.23-32
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• 1975

In order to study the dally metabolism of sodium chloride and of nitrogen, 24-hour urine samples were collected from 1,593 normal Korean females whose ages varied from 2 to 80 years old. The volume, the concentration of chloride and the osmolality of the urine, add the total nitrogen were determined, along with the resting pulse rate and the blood pressure. The daily urine volume was maintained at $1,000{\sim}1,300\;ml/m^2/day$ in all age groups while the chloride concentration and osmolality of the urine samples were approximately 200 mEq/liter and 600 milliosmoles, respectively, in most of age groups. Hence the daily urinary output of sodium chloride was estimated to be approximately $15g/m^2$/day in adult groups. On the other hand, the daily excretion of total nitrogen amouted to approximately $5{\sim}6g/m^2/day$. These findings indicated that the average Korean females live on low-protein and high-salt diets throughout their life. Despite a known correlation between the incidence of hypertension and the high salt intake, none of the subjects employed in this work showed any sign of hypertension.

• 한국환경과학회지
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• 제16권1호
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• pp.45-53
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• 2007

This study was carried out to investigate the variation of organic, nitrogen and phosphorus in $(AO)_2$ SBBR process according to the variation of operating cycle at the high TOC concentration. The operation time in anoxic (anaerobic) time to oxic time was 1:1. Three lab-scale SBBRS were fed with synthetic wastewater based on glucose as carbon source, The variation of total TOC removal was similar each other irrespective of operation time, however, the TOC concentrations in SBBRs showed a little difference according to the operating condition. In SBBR, complete nitrification was not occurred at all reactors, however, R3 showed a higher nitrification than R2. And in SBBR, the variation of operating time more affected at phosphorus removal than nitrogen removal. R2 which had the shortest time at the 1st aeration time showed the lowest phosphorus release and uptake efficacy.

• 한국환경보건학회지
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• 제31권2호
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• pp.152-159
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• 2005

Laboratory scale experiments were conducted to study the applicability, and to compare the performance of two types of sequencing batch reactor (SBR)systems, a conventional SBR and sequencing batch biofilm reactor (SBBR) on the biological nitrogen and phosphorus removal. The nitrification rate in SaR was higher than that in SBBR both in high influent TOC concentration. The denitrification was completed at the first non-aeration period in SBR, however, the additional non-aeration period should be installed or the first aeration period should be extended more in order to complete the nitrogen removal in SBBR. The time at the first aeration period was more needed as about 4-5 h in order to uptake all the released $PO_4^{3-}\;-P$ at the first non-aeration period. SBBR needed more operation time, especially the first aeration time, than SBR at the high influent TOC concentration in order to complete nitrogen and phosphorus removal.

• The Korean Journal of Physiology
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• 제1권2호
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• pp.193-197
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• 1967

In order to study the daily metabolism of sodium chloride and of nitrogen, 24 hour urine samples were collected from 298 normal Korean males whose ages varied Iron 26 to 80 years old. The volume and the concentration of chloride and the total nitrogen were determine, along with the resting pulse and the blood pressure. The daily urine volume was maintained at approximately $1,000\;ml/m^2$ in all age groups while the chloride concentration was at approximately 230 mEq/l. Hence the daily urinary output of sodium chloride was estimated to be approximately 21 gm. On the other hand, the daily urinary output of total nitrogen amounted to approximately 10 gm. Theses findings are similar to those obtained earlier by Yi et al. (1966) in Korean subjects younger than 25 fears old, indicating that average Koreans live on low protein and high salt diets throughout their life. Despite a known correlation between the incidence of hypertension and the high salt intake, none of the these subjects employed in the present investigation showed any sign of hypertension.

• Asian-Australasian Journal of Animal Sciences
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• 제17권4호
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• pp.479-484
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• 2004

The study was conducted to assess the effect of milk production, parity, stage of lactation, season and individual milk components themselves on milk urea nitrogen (MUN) concentration and other milk components of 3,219 Holstein dairy cows in Korean dairy farms. The MUN concentrations in Korean dairy cows were estimated to 16.68$\pm$5.87 mg/dl. Milk yield was negatively correlated with fat and protein contents and somatic cell counts (SCC) in milk (p<0.01). The increasing MUN concentration has positive correlation with yield and fat content. By increasing somatic cell, milk yield was reduced and MUN level was increased. Cows in spring and winter produced more milk over 1.43 and 0.93 kg/day, respectively, than cows in summer (p<0.01). Milk urea nitrogen concentrations of milk produced in summer and fall were significantly lower (p<0.01) than those in spring and winter. Both MUN concentration and somatic cell counts were highest in winter. Milk yield was lower (p<0.01) in the first calving than other calving time and was tended to increase until the fifth parity and then decrease. Milk urea nitrogen and SCC were not related to parity of cows in this study. Milk yield and SCC were positively related to lactation period while MUN concentrations and milk fat and protein contents were negatively influenced by stage of lactation. In the present study, the relationship between MUN and reproduction of dairy cows was also investigated. Cow produced milk in high MUN concentrations (greater than 18 mg/dl) had more open days than cows in MUN concentrations less than 18 mg/dl. However, no significant difference between MUN concentration levels and frequency of artificial insemination was found in this study. It is suggested that although MUN values for nutritional management and measures of production or reproduction are used, non-nutritional factors should be considered.

• Journal of Microbiology and Biotechnology
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• 제9권6호
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• pp.751-756
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• 1999

For mass production of poly(3-hydroxybutyrate) (PHB), high cell density cultures of Ralstonia eutropha were carried out in 2.5-1 and 60-1 fermentors by two fed-batch culture techniques of nitrogen and phosphate limitation. When the nitrogen limitation technique was employed using both an on-line glucose monitoring and control system, a high concentration level of PHB (121g/l) was obtained in the small-scale fermentor of 2.5 1. However, the PHB concentration obtained in a large-scale fermentor of 60 1 only turned out to be 60g/l. In contrast, when another fed-batch culture technique of the phosphate-limitation employing dissolved oxygen (DO) stat glucose feeding was used, a large amount of PHB was successfully produced in both 60-1 and 2.5-1 fermentors. In a 2.5-1 fermentor, concentrations of PHB and cells obtained in 58 h were 175 and 210 g/l, respectively, which corresponded to the PHB productivity level of 3.02 g/l/h. In a 60-1 fermentor, a final cell concentration of 221 g/l and a PHB concentration of 180 g/l with PHB productivity level of 3.75 g/l/h were obtained in 48h. PHB content and yield from glucose were 81% and 0.38g PHB/g glucose, respectively. These data suggest that the phosphate limitation technique is more effective compared to nitrogen limitation in the mass production of PHB by R. eutropha of a large scale.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.325-328
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• 2002

Sucrose 의 경우 저농도에서는 후반부로 갈수록 세포생장 속도는 현저히 감소하는데 비해 hGM-CSF 생산은 후반부에 급격히 증가함을 확인하였다. 고농도 sucrose를 사용하는 경우에는 lag phase가 길어지는 동안에 hGM-CSF의 생산이 증가하였다. 따라서 배양 초기에는 고농도 sucrose가, 배양 후반에는 저농도 sucrose로 존재하는 경우에 hGM-CSF를 많이 얻을 수 있었다. Nitrogen source의 농도는 60.52 mM과 121.04 mM일 때가 세포의 생장이나 hGM-CSF의 생산을 증가시켰으며, phosphate의 경우에는 4.96 mM 일 때가 대조구인 2.48 mM 일 때보다 hGM-CSF의 생산을 3 배 증가시켰다.

• 한국초지조사료학회지
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• 제12권2호
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• pp.104-110
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• 1992

This experiment was carried out to determine the effects of nitrogen(N) fertilization levels(0. 120, 240 and 360 kg/ha/y) on seasonal nitrate nitrogen($NO_3$-N) concentration and water soluble carbohydrate (WSC) content of grasses grown under shading condition. The plants were sampled on 7. 14, 21, 28 and 35 days after harvesting in spring(May), summer(July) and autumn(September), 1988. respectively. Shading degree was controlled artificially ca. 45-50%, and each annual level of N was distributed 5 times equally. The $NO_3$-N concentration of grasses was very low(0.064 %) in spring, high in summer(O.l98 %) and autumn(0.234%), and NO,-N was slightly decreased with growing of grasses. Also the NO,-N concentration of grasses was increased significantly with increasing level of N. In spring, the $NO_3$-N of grasses was very safety(less than 0.1 %), regardless of plant height and N level. In summer and autumn, however, plant heights of below 40 cm(summer) and 44 cm(autumn), and N levels of over 210 kg(summer) and 140 kg(autumn) were over toxic level to animals, respectively. The WSC content of grasses was slightly decreased with grass growth. and significantly decreased with high level of N. From the above results, it is suggested that 200 kg/ha of N in this experiment is effective for forage quality. Also a little more amount of N(50-70kgltimes) in spring. and low level of N(20-30 kgltimes) in summer and autumn season may be desirable on woodland posture.