• Korean Journal of Environmental Biology
• /
• v.31 no.4
• /
• pp.362-369
• /
• 2013

Phytoplankton and zooplankton communities were investigated from 8 weir sites of the Nakdong River system to provide basic information on plankton community after weir construction and to estimate its effects on major water quality parameters. The relationship between plankton community structure and environmental factors was analysed with CCA (Canonical Correspondence Analysis). The results suggested that discharge and total phosphorus and nitrogen concentrations are important factors determining the phytoplankton species composition. For zooplankton community, the difference in discharge between September and October induced different distribution pattern of zooplankton community with more homogeneous distribution with extreme dominance of rotifers during the high discharge season. Chlorophyll a concentration representing phytoplankton biomass has been suggested as the main environmental factor affecting zooplankton community followed by COD and total nitrogen concentration.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.6 no.2
• /
• pp.187-201
• /
• 1996

This study was to evaluate the efficiency of diffusive monitor using activated carbon fiber(ACF, KF-1500) in measuring airborne organic solvents. The following characteristics were identified and studied as critical to the performance of diffusive monitor; recovery, sampling rate, face velocity, reverse diffusion and storage stability. For the evaluation of the performance of this monitor, MIBK, PCE, toluene were used as organic solvents. In the sampling rate experiments, eight kinds of solvents (n-hexane, MEK, DIBK, MCF, TCE, CB, xylene, cumene) as well as the above solvents were used. The results were as follows: 1. The desorption efficiencies(DE's) of ACF diffusive monitor ranged from 83 % to 101 %. In contrast, those of coconut shell charcoal ranged from 78 % to 102 %. Especially, the DE's of ACF for the polar solvents such as MEK were superior to those of charcoal. 2. Experimental sampling rates on ACF were average 42ml/min(37-46ml/min) for 11 organic solvents at $24{\pm}2^{\circ}C$, $50{\pm}5%RH$. However ideal sampling rates(DA/L) were 33 % higher than experimental sampling rates. 3. The initial response(15~16 min) of the testing monitor was 2 times higher than the actual concentration determined by the reference methods at $24{\pm}2^{\circ}C$, $8{\pm}5%RH$ and $80{\pm}5%RH$. Within 1 hours, the curve reached a linear horizontal line at low humidity condition. But sampling efficiencies decreased with respect to time at high humidity condition. And sampling efficiencies were higher at high humidity condition than low humidity condition for MIBK. 4. At very low velocity (less than 0.02 m/sec), the concentration of ACF diffusive monitor were poorly estimated. But ACF diffusive monitor were not affected at higher velocity(0.2 m/sec-0.6 m/sec). 5. There was no significant reverse diffusion when the ACF monitors were exposed to clean air for 2 hours after being exposed for 2 hours at the level of 1 TLV. 6. There was no significant sample loss during 3 weeks of storage at room temperature and 5 weeks of storage at refrigeration.

• Economic and Environmental Geology
• /
• v.40 no.2 s.183
• /
• pp.209-221
• /
• 2007

Numerical analysis was performed to investigate the effect of heavy metal contamination on neighboring environment in case a dam is constructed by using rockfill materials contaminated by heavy metals. The numerical simulation carried out in this research includes both subsurface flow and contaminant transport in the inside of the CFRD(Concrete Faced Rockfill Dam), using two commercial programs, SEEP2D and FEMWATER. The three representative cases of scenarios were chosen to consider a variety of cases occurring in a dam site; (1) Scenario 1 : no crack in the concrete face slab, (2) Scenario 2 : a crack In the upper part of face slab, and (3) Scenario 3 : a crack between plinth and face slab in the lower part of face slab. As a result of seepage analysis, the amount of seepage in scenario 2 was calculated as $14.31\sim14.924m^3/day$ per unit width, corresponding to the 1,000 times higher value than that in other scenarios. Also, in the simulation of contaminant transport by using FEMWATER, specified contaminant concentration of 13 ppb in main rockfill zone was set to consider continuous leakage from the rock materials. Through the analysis of contaminant transport, we found that elapsed times to take for the contaminant concentration of about 2 ppb to arrive at the end of a dam are as follows. Scenario 1 has the elapsed time of 55,000 years. In Scenario 2. it is 50 years. Finally, scenario 3 has 27,000 years. The rapid transport of the contaminant in scenario 2 was attributed to greater seepage flow by 500 times than other scenarios. Although, in case of upper crack in the face slab, it was identified that the contaminant might transport to the end of a dam within 100 years with about 2 ppb concentration, however, it happened that the contaminant was hardly transported out of the dam in other scenarios, which correspond to either no crack or a crack between plinth and face slab. In conclusion, the numerical analysis showed that the alternative usage of the contaminated sand and gravel as the dam embankment material can be one of the feasible methods with the assumption that the cracks in a face slab could be controlled adequately.

• Korean Journal of Environmental Agriculture
• /
• v.22 no.2
• /
• pp.166-171
• /
• 2003

A total of 498 agricultural reservoirs ranging from $164{\times}10^3\;m^3$ to $253{\times}10^6\;m^3$ in storage volume were investigated from 1990 to 2001 with respect to Chl-${\alpha}$, COD concentration and pollutant loading of BOD, TN, and TP. The lakes and reservoirs could be classified to 4 types using the relationships between the ratio of storage volume per water surface area(ST/WS) and Chl-${\alpha}$ concentration. It is recommended that the improvement of polluted lakes should be performed in the order of integrated consolidation type ${\rightarrow}$ watershed consolidation type ${\rightarrow}$ in-lake consolidation type ${\rightarrow}$ Management type and reservoir should be constructed to be over $5{\sim}6\;m$ in depth(ST/WS ratio) for preventing the eutrophication of agricultural reservoirs. We propose that water quality criteria for agricultural water is changed from less than 8 mg/L to less than 6 mg/L for safety value, $6{\sim}10\;mg/L$ for concern value, and more than 10 mg/L for countermeasure value in COD concentration, respectively.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.7 no.2
• /
• pp.233-244
• /
• 1997

In order to investigate the concentration of trace metals in human hairs from residents living in urban area and rural area, the 120 hair samples of adults were taken from urban areas(industrial area, bus terminal, downtown area) and rural area(Kasan-ri, Yeoju-up, Yeoju-goon) during July - September 1995. Mean concentrations of trace metals including lead and cadmium in human hair were compared by region, sex, presence of smoker, type of water, period of residence. The results were as follows; 1. The average concentrations of lead and cadmium in hairs of urban area are $0.92{\mu}g/g$ ($1.01{\mu}g/g$ industrial area, $1.01{\mu}g/g$ bus terminal, $0.74{\mu}g/g$ downtown area), $0.38{\mu}g/g$ ($0.54{\mu}g/g$ industrial area, $0.49{\mu}g/g$ bus terminal, $0.12{\mu}g/g$ downtown area). The mean concentrations of lead and cadmium in urban area are higher than the corresponding levels in the rural area. 2. Lead concentration for male in the urban and rural area is 0.94 and $0.62{\mu}g/g$, 0.90 and $0.60{\mu}g/g$ for female. But, It does not have any statistical significance. Cadmium concentration for male in the urban and rural area is 0.38 and $0.12{\mu}g/g$, 0.38 and $0.11{\mu}g/g$ for female. But It does not have any statistical significance. 3. Mean concentrations of lead and cadmium in smokers shows higher than non-smokers. It showed that the longer period of residence in urban area, the higher concentrations of three metals.

• Journal of Soil and Groundwater Environment
• /
• v.16 no.5
• /
• pp.53-66
• /
• 2011

Groundwater which infiltrated in recharge areas discharges in the forms of evapotranspiration, baseflow to streams, groundwater abstraction and eventually flows into the sea. This study characterized radon-222 concentration and electrical conductivity (EC) in coastal groundwater discharge, well groundwater, Ilkwang Stream water, and seawater in the coastal area of Busan Metropolitan City and subsequently estimated groundwater discharge rate to the sea. The median value of Rn-222 concentration is highest in well groundwater (18.36 Bq/L), and then decreases in the order of coastal groundwater discharge (15.92 Bq/L), Ilkwang Stream water (1.408 Bq/L), and seawater (0.030 Bq/L). The relationship between Rn-222 concentration and EC values is relatively strong in well groundwater and then in seawater. However, the relationship is not visible between coastal groundwater discharge and Ilkwang Stream water. The groundwater discharge rate to the sea is estimated as $3,130m^3$/day by using radon mass budget model and $16,788m^3$/day by using Darcy's law.

• Korean Journal of Environment and Ecology
• /
• v.29 no.6
• /
• pp.929-935
• /
• 2015

This study was carried out to investigate pH, EC, solutes concentration and ANC characteristics in coniferous forest experiment watershed in Gyeonggi-do, Korea from 2005 to 2007. The average pH value was 6.87 and low at spring season due to deposition in crown. The average EC was $58.4{\mu}S/cm$ and was high at spring season due to high concentration of solutes. The cation and anion concentration was high at spring and fall season with low rainfall. When stream water quality was compared to different watershed, EC was relatively low due to high rainfall and $NO_3{^-}$ was high due to deposition and forest practice. pH and ANC was relatively constant at stream water

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.34 no.3
• /
• pp.47-57
• /
• 2022

We carried out studies on prediction in concentration of dissolved oxygen (DO) with LSTM model and prediction in occurrence of hypoxia water mass (HWM) with decision tree. As results of study on prediction in DO concentration, a large number of Hidden node caused high complexity of model and required enough Epoch. And it was high accuracy in long Sequence length as prediction time step increased. The results of prediction in occurrence of HWM showed that the accuracy of nonHWM case was 66.1% in 30 day prediction, it was higher than 37.5% of HWM case. The reason is that the decision tree might overestimate DO concentration.

• Applied Chemistry for Engineering
• /
• v.34 no.6
• /
• pp.649-659
• /
• 2023

This study was initiated to evaluate the phosphorus (P) removal and diesel oil degradation by bacteria isolated from industrial wastewater. The bacteria isolated were identified as Bacillus sp. The P removal efficiencies by Bacillus sp. were 99% at the initial 20 mg/L P concentration. The diesel degradation efficiencies by Bacillus sp. were 86.4% at an initial 1% diesel concentration. Lipophilicity by bacteria was the highest in the log phase, whereas it was the lowest in the death phase. As the diesel was used as a carbon source, P removal efficiencies by Bacillus sp. were 68%. When glucose, acetate, and a mixture of glucose and acetate as second carbon sources were added, the diesel degradation efficiencies were 69.22%, 65.46%, and 51.46%, respectively. The diesel degradation efficiency was higher in the individual additions of glucose or acetate than in the mixture of glucose and acetate. When P concentration increased from 20 mg/L to 30 mg/L, the diesel degradation efficiency was increased by 7% from 65% to 72%, whereas when P concentration was increased from 30 mg/L to 40 mg/L, there was no increase in diesel degradation. One of the five proteins identified by proteome analysis in the 0.5% diesel-treated samples may be involved in alkane degradation and is known as the cytochrome P450 system. Also, two of the sixteen proteins identified in the 1.5% diesel-treated samples may be implicated in the fatty acid transport system and alcohol dehydrogenation.

• Journal of the Korean Regional Science Association
• /
• v.6 no.2
• /
• pp.123-147
• /
• 1990

This paper examines the changing geography of producer service industries in the 1980s. The foci of this study are to analyze the regional distribution of each producer services, and to reveal the spatial linkage of producer services. Further this paper asserts the potential role of producer services for reducing the potential endogenous development in the periphery. During the 1981-86 period, producer service industries grew more rapidly than other service sectors and manufacturing sector. The main reason of the raid growth of producer services is attributable to an increase in demand for intermediate services from manufacturing firms. In order to compete an increasingly complex business environment, firms have expanded the amount of effort devoted to activities such as planning, coordination and control, and consequently have increased their use of producer services. The most distinctive feature of the location of producer services is spatial concentration into Seoul and surrounding region. Especially the degree of the concentration o business services into the Capital Region has been accelerating during the 1990s. The pattern of employment growth and regional distribution of producer services show a clear core / periphery disparity. Much of the regional inequality in producer services is largely due to variation in demand associated with the pattern of corporation headquarters with the pattern of corporation headquarters and branch plants location with large manufacturing firms. The analysis of spatial division of labor reflects that producer services are related to the location of headquarters in manufacturing industry. Headquarters in manufacturing firms and business service firms tend to cluster each other. Most of the headquarters spatially separated from branch offices are clustered heavily in Seoul. Especially headquarters of business services and insurance services are overwhelmingly concentrated into Seoul. The firms whose headquarters are located in Seoul have a linkage pattern on a nationwide scale. It is viewed have little potential for generating local multiplier effects and regional development. In the light of the result of this study, producer services are not likely to disperse soon to peripheral regions. Consequently the absence of policies directed at enhancing producer sevice in the periphery, concentration tendency would continue to reinforce the core's dominance at the expense of peripheral regions. From a regional perspective, the quality of a region's producer service sector is a key determinant of economic growth, since manu industrial location decisions are influenced by the differential availability of producer services among regions. Poor performance of producer services in peripheral regions seemed to be linked to the region's manufacturing base. Low-wage, standardized branch plants are not likely to induce the growth in knowledge intensive services associated with high-technology corporate headquarters. Producer services may help to create and attract new business including manufacturing firms, and also to enhance the productivity and competitiveness of local firms. Therefore the provision of service producing activities would be lead not only to generate and retain endogenous development but also to attract external firms, especially small and medium sized firms which have a lower propensity of internalized services. Hence, it may be more efficient to create and expanse new locally owned producer services rather than to attract branch plants of mult-locational firms in order to make indigenous economic development.