• 한국방재학회 논문집
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• 제6권1호
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• pp.83-95
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• 2006

본 연구는 강우시 소하천 수로구간에서 유사농도의 연직분포를 유사량 측정기 (ASM-IV)로 실측하여 그 특성을 분석하고자 한다. 이를 위해 충남 연기군 서면에 위치한 월하천 시점부분의 수로구간을 연구대상으로 선정하였다. 실측된 부유사농도의 분석자료는 상하류구간에서 각각 1시간 11분 30초 및 40분 32초 동안에 2초 간격으로 측정된 2,145개 및 1,216개중 16개씩의 시간구간 자료가 사용되었다. 분석한 결과, 상류구간의 실측치 Rouse 수는 $0.00129{\sim}0.02394$로 분포하고, 평균값은 0.01129로 나타났으며, 하류구간에서는 $0.00118{\sim}0.00822$, 평균값은 0.00436으로 하류의 값이 상류의 값보다는 훨씬 작게 분포하는 것으로 나타났다. 계산치 Rouse 수는 상류구간의 경우 $0.065115{\sim}0.065295$, 평균값은 0.06521로 나타났고, 하류구간의 경우에는 $0.057315{\sim}0.059109$, 평균값은 0.05795로 하류구간이 상류구간보다 약간 작은 값을 갖으나, 실측치 비교에서의 차이보다는 적게 나타났다. 그러나 실측치와 계산치의 비교에서는 상류구간보다 하류구간에서 더 큰 차이를 갖는 것으로 나타났는데, 이 오차는 하류구간의 침강속도 산정시 높은 수온에 대한 동점성계수 값을 본 연구에서 유도한 경험식으로 계산한 것도 원인중의 하나에 포함될 것이다.

• 생물환경조절학회지
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• 제15권3호
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• pp.264-269
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• 2006

본 실험은 배양액의 농도가 무화과의 생육과 수량에 미치는 영향을 조사하기 위하여 수행하였다. 1차 실험에서 배양액의 농도에 따른 무화과 생육은 1/2농도 처리구에서 초장, 엽수, 경경, 착과수가 양호했으며, 엽장과 엽폭은 1/2농도구를 제외한 다른 처리간에는 차이가 없었다. 배양액의 농도에 따른 과식의 평균과중은 토양재배의 38.4g보다 수경재배에서 50.9g으로 높게 나타났고, 과장, 과경, 당도는 처리간의 차이가 없었다. 수확량은 토양재배보다 수경재배에서 월등하게 많았으며, 배양액 1/2농도보다 2/2와 3/2농도에서 높게 나타났다. 무화과의 수경재배에서 저농도에서 양호한 생육을 나타내었으며, 수량은 높은 농도에서 양호하였다. 본 실험의 결과는 무화과의 수량 및 품질증대에 유용하게 활용될 수 있을 것이다.

• 한국산업보건학회지
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• 제24권3호
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• pp.336-344
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• 2014

Objectives: This study was performed to assay the effect of neodymium oxide on the generation of reactive oxygen species and DNA oxidative damage by intratracheal instillation. Methods: Two groups of rats were exposed to neodymium oxide($Nd_2O_3$) via intratracheal instillation with doses of 0.5 mg and 2.0 mg, respectively. At two days and at 12 weeks after exposure, the contents of neodymium oxide in the lung, liver, kidney, heart and brain, leukocyte, olive tail moment, ROS, RNS, lactate dehydrogenase, albumin, cytokine and MDA from BALF were measured. Results: Neodymium oxide contents in the liver, kidney, heart, and brain were detected at less than $1{\mu}g/g$ tissue concentration. However, in the lungs at four weeks the highest amount were detected and then found to be drastically reduced at 12 weeks. ROS and RNS in bronchoalveolar lavage increased in concentration dependently at two days, four weeks and 12 weeks after neodymium oxide instillation. However, ROS and RNS decreased with the passage of time. At two days the total number of WBC in BALF in the high concentration group was significantly increased, and at four weeks the total number of WBC were significantly increased in the low and high concentration groups(p<0.01). At two days after exposure, the LDH of the low and high concentration groups was significantly increased. At 12 weeks, only the LDH of the high concentration group was significantly increased compared to in the control group(p<0.01). As a result of Comet assay, after two days, damage to the DNA of the low and high concentration groups was observed. Conclusions: Intratracheal instillation of neodymium oxide induces the generation of ROS and DNA damage in rats.

• 한국대기환경학회지
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• 제2권2호
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• pp.41-50
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• 1986

Urban aerosol concentrations in the size range of $0.01 \sim 1.0 \mum$ have been measured by using an electrical aerosol analyzer from May through October, 1984. The total diurnal variation of the number concentration indicates that a minimum value is observed at 3 hr and a sharp increase is noticed early in the morning with a subsequent slow and continuous increase from around 7 hr until 20 hr. After that it is decreased to reach its minimum by dawn. However, both surface and volume concentrations have shown that their first maxima at 8 hr and their second at about 20 hr simultaneously. It is found that the aerosol number is mainly governed by the particles in the size range of $0.01 \sim 0.1 \mum$, while most volume is in $0.1 \sim 1.0 \mum$ size range. It is known fact that particles of $0.1 \sim 1.0 \mum$ size range affect the visibility reduction in the atmosphere. The monthly variation of aerosol concentration remarks its minimum in summer. The main factors influencing the aerosol concentration are emission of autoexhausts, various processes of production and removal, and meteorological parameters.

• 한국가시화정보학회지
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• 제6권2호
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• pp.45-50
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• 2008

It has been found that the colony size of bacteria grown on an agar plate decreases with increasing agar gel concentration. Evidenc from recent studies suggests that the bacterial colony dynamics is closely related with the mechanical properties of the substrate. We investigate whether bacterial growth on the agar substrate is controlled mostly by the nutrients' diffusion which is hindered more in porous medium than in solution. The number of bacterial cells in single colonies is found to be inversely correlated with agar concentration. High-resolution live cell imaging at the single bacterium level confirms that the bacterial growth rate is reduced with increasing agar concentration. There is a strong correlation between the slowed diffusion and the reduced number of cells in a high concentration of agar medium.

• 상하수도학회지
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• 제32권5호
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• pp.411-419
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• 2018

The residual chlorine concentration is an essential factor to secure reliable water quality in the water distribution systems. The chlorine concentration decays along the pipeline system and the main processes of the reaction can be divided into the bulk decay and the wall decay mechanisms. Using EPANET 2.0, it is possible to predict the chlorine decay through bulk decay and wall decay based on the pipeline geometry and the hydraulic analysis of the water distribution system. In this study, we tried to verify the predictability of EPANET 2.0 using data collected from experimental practices. We performed chlorine concentration measurement according to various Reynolds numbers in a pilot-scale water distribution system. The chlorine concentration was predicted using both bulk decay model and wall decay model. As a result of the comparison between experimental data and simulated data, the performance of the limited $1^{st}$-order model was found to the best in the bulk decay model. The wall decay model simulated the initial decay well, but the overall chlorine decay cannot be properly predicted. Simulation also indicated that as the Reynolds number increased, the impact of the wall.

• Mycobiology
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• 제33권4호
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• pp.194-199
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• 2005

Application of fertilizers such as urea, diammonium phosphate (DAP) and muriate of potash in soil adversely affected the spore germination of Arthrobotrys dactyloides. Amendment of soil with urea at the concentrations of 1.0%, 0.5% and 0.1 % completely inhibited spore germination and direct trap formation on the conidium, whereas muriate of potash delayed and reduced the spore germination even at the lowest concentration. DAP also inhibited spore germination at 1.0% concentration, while at lower concentration the percentage of spore germination was reduced. Application of neem cake at the concentration of 0.5% also inhibited spore germination after 24 h of amendment. The inhibitory effect of neem cake was reduced after 15 days of amendment, while after 30 days after amendment the inhibitory effect was completely lost and the spore germinated by direct trap as in unamended soil. Nematodes were not attracted to ungerminated spores after 24 h of amendment. After 15 days of amendment nematodes were attracted to agar blocks containing fewer germinated spores after 24 h of incubation but after 48 h of incubation large number of nematodes were attracted and trapped by the germinated spores with direct traps. After 30 days of amendment, larger number of nematodes were attracted and trapped by direct traps.

• 한국수산과학회지
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• 제29권6호
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• pp.828-836
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• 1996

The histological changes of gill, liver, spleen and muscle, and respiration and blood variables and liver glycogen content were examined in black seabream, Acanthopagrus schlegeli. Fish were exposed to a high level of total ammonia nitrogen (10.4 mg/l) and recovered from exposure $(0.4{\pm}0.2mg/l)$ in a closed recirculating seawater system. In the process of exposure, mortality was $9\%$, and hyperplasia, necrosis or inflammation appeared in all tissues except for muscle. Oxygen consumption was decreased by $49\%$, and red blood cell (RBC) number, hematocrit and hemoglobin concentration were significantly decreased, while plasma glucose contents, activities of glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) increased. Liver glycogen content significantly increased from $6.6\%\;to\;10.4\%$. A large amount of hemosiderin was observed in the splenic tissue. During the recovery period, RBC number, hematocrit, hemoglobin concentration, GOT and GPT activities were returned to the normal status. Histological status of liver tissue was returned to the normal, but liver glycogen content was not recovered. During the recovery period, spleen melanin-macrophages temporarily increased, but subsequently decreased to the normal status.

• Advances in environmental research
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• 제4권1호
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• pp.1-15
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• 2015

A pot experiment was conducted to assess the effects of red pepper (Capsicum annuum) and coriander (Coriandrum sativum) on seedling growth of wheat (Triticum aestivum). The aqueous extracts treatment of red pepper and coriander showed a significant (p < 0.05) reduction in root, shoot and seedling length, number of leaves and seedling dry weight of wheat (T. aestivum) as compared to control. The inhibitory different effect on growth of wheat (T. aestivum) was directly proportional to the increasing concentration (1, 2, 3, 4 and 5%) of aqueous extracts of red pepper and coriander as compared to control treatment (0%). The root, shoot, seedling length and number of leaves of T. aestivum significantly p < 0.05 decreased at 5% concentration of red pepper as compared to control. The root, shoot and seedling growth of T. aestivum was also significantly reduced at 1, 2, 3, 4 and 5% concentration of coriander as compared to control. The root, shoot and leaves dry weight of T. aestivum at 5% coriander extract treatment concentration decreased as compared to control. The tolerance in seedlings of T. aestivum to red pepper and coriander extract treatment was dose dependent as compared to control. The seedlings of T. aestivum showed low percentage of tolerance to pepper extract treatment than coriander extract treatment.

• Journal of Preventive Medicine and Public Health
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• 제29권4호
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• pp.863-875
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• 1996

In order to prepare the fundamental data for the health promotion by assessing the exposure level of styrene, the author determined the concentration of mandelic acid and phenylglyoxylic acid in urine of 42 workers who were exposed to styrene by high performance liquid chromatography and surveyed 16 symptoms, by questionnaire and also tested neurobehavioral test(digit symbol, benton visual retention) in 2 FRP plants of Kyung Nam area from July to September, 1995. Control was sampled by age sex matching method. The concentration of styrene in air was determined by gas chromatography. The results were as follows; 1. Geometric mean concentration of styrene in air was 17.4ppm, geometric mean concentration of mandelic acid(MA) in urine were 404.3mg/g creatinine for exposure group, 46.4mg/g creatinine for control group, geometric mean concentration of phenylglyoxylic acid(PGA) in urine were 57.5mg/g creatinine for exposure group, 9.5mg/g creatinine for control group. Mean concentration of MA and PGA showed statistically significant difference between exposure group and control group(p<0.01). 2. Number of symptom were 2.9 for exposure group, 3.3 for control group, number of digit symbol were 24.1 for exposure group, 32.5 for control group, number of Benton visual retention test were 6.1 for exposure group, 6.0 for control group, respectively. As result of adjusting the education year, number of Benton visual retention test showed statistically significant difference between exposure group and control group(p<0.05). 3. Excellent correlation were observed between environmental styrene exposure and urinary MA(r=0.80), PGA(r=0.73), and MA+PGA(r=0.81).