간행물
한국환경과학회지 KCI 등재 Journal of Environmental Science International
- 발행기관 한국환경과학회
- 자료유형 학술지
- 간기 월간
- ISSN 1225-4517 (Print)2287-3503 (Online)
- 수록기간 1992 ~ 2023
- 주제분류 자연과학 > 자연과학일반 자연과학 분류의 다른 간행물
- 십진분류KDC 539DDC 628
권호리스트/논문검색
제16권 제4호 (2007년 4월) 15건
1.
2007.04
서비스 종료(열람 제한)
The sonolytic decomposition of NHCs(Nitrogen Heterocyclic Compounds), such as atrazine[6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine], simazine(6-chloro-N,N'-diethyl-1,3,5-triazine-2,4-diamine), trietazine(6-chloro-N,N,N'-triethyl-1,3, 5-triazine-2,4-diamine), in water was investigated at a ultrasound frequency of 200kHz with an acoustic intensity of 200W under argon and air atmospheres. The concentration of NHCs decreased with irradiation, indicating pseudo-first-order kinetics. The rates were in the range 1.06∼2.07(×10−2min−1) under air and 1.30∼2.59(×10−2min−1) under argon at a concentration of 200μM of NHCs. The rate of hydroxyl radicals(∙OH) formation from water is 19.8μMmin−1 under argon and 14.7μMmin−1 under air in the same sonolysis conditions. The sonolysis of NHCs is effectively inhibited, but not completely, by the addition of t-BuOH(2-methyl-2-propanol), which is known to be an efficient ∙OH radical scavenger in aqueous sonolysis. This suggests that the main decomposition of NHCs proceeds via reaction with ∙OH radical; a thermal reaction also occurs, although its contribution is small. The addition of appropriate amounts of Fenton's reagent [Fe2+] accelerates the decomposition. This is probably due to the regeneration of ∙OH radicals from hydrogen peroxide, which would be formed from recombination of ∙OH radicals and which may contribute a little to the decomposition.
2.
2007.04
서비스 종료(열람 제한)
The characteristics of meteorological conditions relevant to Asian dust (AD) outbreaks and their occurrence frequencies were analyzed in four source regions (R1 to R4) during spring months (March to May) of 1998-2002. Moreover, the concentration variations of AD (e.g., PM10) observed in Korea were investigated during the study period. In the relationship between AD outbreaks and three meteorological parameters (i.e., air temperature, wind speed, and aridity), the largest AD outbreaks in April (～250 observations) mostly occurred in R2 when air temperature ranging from 10.0 to 15.0℃ and surface wind speed from 7 to 9 m s-1 were recorded. Moreover, the aridity (≥ 4) in April was significantly high in R2 with the maximum frequency of AD outbreaks (i.e., 206 observations). On the other hand, the number (percentage) of days belonging to AD events observed in five Korean cities were found to be 116 (44%), 121 (46%), and 26 days (10%) in March, April, and May, respectively. The mean PM10 concentrations were found to range from 150 to 220, 150 to 200, and 95 to 120 ㎍ m-3 in March, April, and May, respectively. Consequently, this implied that the AD events in Korea were found to be gradually frequent in early spring and to be affected from the large AD outbreaks observed in the source regions.
3.
2007.04
서비스 종료(열람 제한)
Effects of dimethipin on α-amylase activity of barley seeds were investigated. In the treatments of 1 μM and 10 μM dimethipin, the indexes of germination were reduced to 17% and 24 % respectively. After seed germination, dimethipin was added to germinated seedlings and then the seedlings were kept to measure seedling length under illumination for 7 days. In control, the length of seedling was 5.7 cm, but in the treatments of 1 μM dimethipin and 10 μM dimethipin, seedling lengths were 5.5 cm and 1.2 cm respectively. In the relationship between dimethipin concentrations and α-amylase activities, there was a linear curve. The more dimethipin was added to the seeds, the more α-amylase activities were inhibited. In the treatments of 1 μM dimethipin and 10 μM dimethipin, α-amylase activities were reduced to 33% and 71% respectively. Dimethipin also inhibited α-amylase activities increased by gibberellin and the content of soluble protein. Therefore, it could be suggested that dimethipin might inhibit directly the activities of hydrolysis enzymes including α-amylase or the expression of α-amylase genes as germination and seedling growth were severely disturbed.
4.
2007.04
서비스 종료(열람 제한)
This study assessed the characteristic of BTEX (Benzene, Toluene, Ethylbenzene, Xylene) concentration ratios of industrial emission sources and the neighborhoods of industrial area, fuel such as gasoline, light oil, LPG, and similar gasoline, and ambient air in Daegu. The BTEX in aromatic compounds was the most abundant VOC in Daegu. The BTEX ratios were (0.2:2.6:1.0:1.8) for the neighborhoods of industrial area, (2.6:11.3:1.0:1.2) for residential area, (2.2:11.0:1.0:1.6) for commercial area, (1.0:14.9:1.0:1.3) for industrial area, and (0.2:2.6:1.0:1.8) for the neighborhoods of industrial area. Average BTEX ratios in Daegu were B/T ratio (0.1), B/EB ratio (1.5), B/X ratio (1.1), T/EB ratio (12.6), T/X ratio(10), EB/X ratio (0.7). Expecially, B/T ratio in Daegu was similar as the other cities, Bangkok, Manila, and Hongkong. Comparing other cities with B/T ratio, the main sources of VOC were vehicular exhaust and emission of industrial facilities. Furthermore, BTEX correlation were evaluated at the emission sources and regional areas. Results showed that correlation coefficient values of emission sources, fuels and neighborhood of industry were significant magnitude above 0.65(p<0.01). Also, there showed highly significant correlations among BTEX. Calculated correlation coefficients of ambient air sampling sites were 0.61～0.954 for commercial /residential area and 0.613～0.998 for industrial area. However, they showed different correlation between commercial/residental area and industrial area. It implied that the emission sources were different from each area.
5.
2007.04
서비스 종료(열람 제한)
The water flea has been used as a test organism of toxicity test for surface water. Toxicity test with water flea is categorized into two parts. One is acute toxicity test with observing immobility and mortality and the other is chronic toxicity test determined by survival and reproduction of water flea. Heartbeat measurement of water flea was designed as a short-term toxicity test in this study. Direct measurement of heartbeat under microscope by aid of video camera gives and early diagnosis of mortality in short time. Therefore, the effects of measuring illumination, measuring time, and non-feeding during the test on heartbeat of water flea was evaluated to establish a new test approach. Test organisms used in this study are Daphnia magna, a well standardizes toxicity test organism, and Simocephalus mixtus, a newly refined organism. IC50 values of these test organism by heartbeat measurement were compared and discussed. It was found that toxicity test by heartbeat measurement was a reproducible, easy and simple method accomplished in a few hours.
6.
2007.04
서비스 종료(열람 제한)
The photodegradation and by-products of the gaseous toluene with TiO2 (P25) and short-wavelength UV (UV254+185nm) radiation were studied. The toluene was decomposed and mineralized efficiently owed to the synergistic effect of photochemical oxidation in the gas phase and photocatalytic oxidation on the TiO2 surface. The toluene by the UV254+185nm photoirradiated TiO2 were mainly mineralized CO2 and CO, but some water-soluble organic intermediates were also formed under severe reaction conditions. The ozone and secondary organic aerosol were produced as undesirable by-products. It was found that wet scrubber was useful as post-treatment to remove water-soluble organic intermediates. Excess ozone could be easily removed by means of a MnO2 ozone-decomposition catalyst. It was also observed that the MnO2 catalyst could decompose organic compounds by using oxygen reactive species formed in process of ozone decomposition.
7.
2007.04
서비스 종료(열람 제한)
This study was carried out to investigate the effect of electrochemical (EC) disinfection of artificial wastewater contaminated by Escherichia coli culture. Circulated batch type electrochemical disinfection system using three plates electrodes was used. Also, the several factors (pH, ORP, DO, temperature, current, conductivity) were measured in order to investigate the fundamental design factor in the EC disinfection system. It was demonstrated that the EC process was highly effective for wastewater disinfection. At the constant voltage, the disinfection efficiency was increased according to time. The disinfection efficiency and current increased as the increase of voltage. The variation of conductivity was a little related to the variation of CFU (colony forming units). The differences in disinfection efficiency according to the ice pack and the variation of electrodes were not occurred. The EC disinfection efficiency and current increased according to the increase of circulating flow rate.
8.
2007.04
서비스 종료(열람 제한)
Study on Filter Drag Due to the Change of Operation Conditions in a Pulse Air Jet-type Bag Filter[Ⅰ]
Research results for the pressure drop variance depending on operation conditions such as change of inlet concentration, pulse interval, and face velocity, etc., in a pulse air jet-type bag filter show that while at 3kg/cm2 whose pulse pressure is low, it is good to make an pulse interval longer in order to form the first layer, it may not be applicable to industry because of a rapid increase in pressure. In addition, the change of inlet concentration contributes more to the increase of pressure drop than the pulse interval does. In order to reduce operation costs by minimizing filter drag of a filter bag at pulse pressure 5kg/cm2, the dust concentration should be minimized, and when the inlet dust loading is a lower concentration, the pulse interval in the operation should be less than 70 sec, but when inlet dust loading is a higher concentration, the pulse interval should be below 30 sec. In particular, in the case that inlet dust loading is a higher concentration, a high-pressure distribution is observed regardless of pulse pressure. This is because dust is accumulated continuously in the filter bag and makes it thicker as filtration time increases, and thus the pulse interval should be set to below 30 sec. If the equipment is operated at 1m/min of face velocity, while pressure drop is low, the bag filter becomes larger and thus, its economics are very low due to a large initial investment. Therefore, a face velocity of around 1.5 m/min is considered to be the optimal operation condition. At 1.5 m/min considered to be the most economical face velocity, if the pulse interval increases, since the amount of variation in filter drag is large, depending on the amount of inlet dust loading, the operation may be possible at a lower concentration when the pulse interval is 70 sec. However, for a higher concentration, either face velocity or pulse interval should be reduced.
9.
2007.04
서비스 종료(열람 제한)
To analyze the water characteristics in the dry and wet seasons, the data for temperature, salinity, nutrients and chl-a were used, which were observed in the south coastal area of Korea during April to October 2000. At Yeosu in the south coast of Korea, the higher values of 35.0 psu in salinity were shown in March and April, the lower values of 23.0 psu in salinity were shown in August and September. The annual range of salinity was 12.0 psu. The total amount of precipitation in the wet season (July to October) was occupied 68% (about 846 mm) during 2000. The precipitation of the dry season (November to June) was occupied 32% (about 394 mm) in the year. In the coastal area, the salinity variation is distinct in the period of July to October. Based on this result, we divided the season into two parts: the dry season during April to June and the wet season during July to October. Factor analysis was shown that temperature has strong negative relation and nutrients show positive relations in the dry season by the factor 1, which explains the total variance of 50.6% at the surface water. In the wet season, salinity has negative relation and nutrients show positive relation by the factor 2, which explains the total variance of 33.5%. The bottom layer also showed similar to those of surface water in the results of factor analysis. These mean that nutrients become rich due to the freshwater inflow in the wet season. The low saline water is shown not only in the south coast but also in the overall region in the South Sea of Korea. It is suggested that the South Sea of Korea may call a ROFI (Region of Freshwater Influence) system in summer.
10.
2007.04
서비스 종료(열람 제한)
A numerical study with Envi-met model is experimented to investigate the characteristics of wind pattern in apartment complex. In all case, most conditions such as wind speed, temperature, and surface features are considered as the same, but wind direction is the only different factor. The wind directions considered in this study have a meaning of prevailing wind direction. When the prevailing wind with the direction of 170° blows into the complex, the ventilation passage toward the outside of complex is formed and the stagnation of air is not expressed. In case of having the direction of 300°, most evident ventilation passages are composed. When the inflow wind direction is the northeast, 30°, there is some possibility of stagnation phenomenon. This is because the arrangement of buildings makes a right angle with the inflow wind direction.
11.
2007.04
서비스 종료(열람 제한)
This study investigated the environmental awareness synthetically with the drawing activity for making up for the weak points in the writing test that cannot measure emotional aspects. This study found that students have negative viewpoints on reasonable judgement for the present and future environment of the earth, while they show hope to live in better environment in their mind. Furthermore, it found that the drawing activity can be adopted as a complement for the traditional measuring method of the environmental awareness, through which this middle school students' sensibility to the environment can be shown. It also inferred that the drawing activity can be used as a way of education during school classes for environment and it can increase the sensibility to the environment in mind.
12.
2007.04
서비스 종료(열람 제한)
In this study is analysis which dams breach shapes are effect on peak discharge of dam-failure. The dam breach shapes and failure time are important peak discharge when dam failure. When dam failure times are 1hr, 2hr and 3hr condition for the ECRD and 0.1hr and 0.2hr for the CG and CFRD that breach shapes changed base length Bb=1Hd, Bb=2Hd and Bb=3Hd. As the results from DAMBRK(Dam Break model) peak discharge are increase base widths lengthen. As failure time is longer then peak discharge is decrease. So peak discharge is increase more short of dam failure time. Also peak discharge is increase become larger dam breach shapes.
13.
2007.04
서비스 종료(열람 제한)
In this study, we took the geometrical character of the river channel junction and hydrologic conditions as independent variables, and hydraulic behavior characteristics as an independent variable. The result, after multiple analysis was carried out, proved that, except for the generating area of the accelerating zone of velocity the accelerating zone and both the main channel and the tributary zone of stagnation the stagnation zone, there was correlation of over 90%. Also, derived presumed expression of the hydraulic characteristics of the junction was applied to the real natural channel - the river channel of the Guem-ho main channel (the A-yang bridge to the Guem-ho bridge). As the result, it proved that it represented hydraulic characteristics relatively well.
14.
2007.04
서비스 종료(열람 제한)
This study estimated response of water quality and pollutant behavior according to the discharge and reuse of treated wastewater by three-dimensional eco-hydrodynamic model, and suggest plan that water quality management and environmental restoration in the coastal area including urban stream of Yeosu, Korea. Dispersions of low-saline water and COD by treated wastewater loads (design facility capacity, about 110,000 m3/d) were very limited in near of effluent site. Nutrients, however, increase compared to the other water quality factors, especially total nitrogen was very sensitive to input loads. When reuse some of treated wastewater to Yeondeung stream, nitrogen was big influence on estuarine water quality. Although current characteristics of treated wastewater such as discharge and water quality were negligible to the change of marine environment, effluent concentration of COD, TN and TP, especially 40% of TN, are reduced within the allowable pollutant loads for satisfy environmental capacity and recommended water quality criteria. Also, controls of input point/non-point sources to Yeondeung stream and base concentration of pollutants in coastal sea itself are very necessary.
15.
2007.04
서비스 종료(열람 제한)
This study utilized the 1/25,000 topographic map of the upper area from the Geum-ho watermark located at the middle of Geum-ho river from the National Geographic Information Institute. For the analysis, first, the influence of the size of critical area to the hydro topographic factors was examined changing grid size to 10m×10m, 30m×30m and 50m×50m, and the critical area for the formation of a river to 0.01㎢∼0.50㎢.
It is known from the examination result of watershed morphology according to the grid size that the smaller grid size, the better resolution and accuracy. And it is found, from the analysis result of the degree of the river according to the minimum critical area for each grid size, that the grid size does not affect on the degree of the river, and the number of rivers with 2nd and higher degree does not show remarkable difference while there is big difference in the number of 1st degree rivers. From the results above, it is thought that the critical area of 0.15㎢∼0.20㎢ is appropriate for formation of a river being irrelevant to the grid size in extraction of hydro topographic parameters that are used in the runoff analysis model using topographic maps. Therefore, the GIUH model applied analysis results by use of the river level difference law proposed in this study for the explanation on the outflow response-changing characters according to the decision of a critical value of a minimum level difference river, showed that, since an ogival occurrence time and an ogival flow volume are very significant in a flood occurrence in case of not undertow facilities, the researcher could obtain a good result for the forecast of river outflow when considering a convenient application of the model and an easy acquisition of data, so it's judged that this model is proper as an algorism for the decision of a critical value of a river basin.
