• 상하수도학회지
• /
• 제32권4호
• /
• pp.337-348
• /
• 2018

As the issue of microplastics (MPs) detection in tap water was raised in other countries in 2017, monitoring of MPs in drinking and source water, and sewage treatment plant (STP) effluents was initiated. This study intends to look into other studies on MPs in STPs at home and abroad, and review the characteristics of MPs and their removal efficiencies in the STPs, the risk and effect of MPs on watersheds, and management practices in order to help better understand MPs in STPs. To manage MPs effectively in STPs, it is necessary to investigate the detection of MPs discharged from STPs, do research on human health risk and control measures, and build a monitoring system including standardized analytical methods.

• 대한기계학회논문집B
• /
• 제26권12호
• /
• pp.1756-1762
• /
• 2002

To effectively meet current regulations on the exhaust emissions of diesel engine required to control the deterioration of air pollution in the whole world, this study is to investigate the effects of water induction through the air intake system on the characteristics of combustion and exhaust emissions in IDI diesel engine. A method fur supplying water through the air intake system to reduce the exhaust emissions has been considered with other methods such as water introduction in the form of water-in-fuel emulsion or water injection directly into the combustion chamber, but it has not been studied about the effects of water on the combustion concepts and the characteristics of exhaust emissions in detail until now. In this study, the formation of NOx was significantly suppressed by decreasing the gas peak temperature during the initial combustion process because the water play a role as a heat sink during evaporating in the combustion chamber, but the smoke was slightly increased by increasing water amount.

• 환경영향평가
• /
• 제18권6호
• /
• pp.401-409
• /
• 2009

Multivariate statistical approaches to classify sampling sites with measuring their similarity by water quality data and understand the characteristics of classified clusters have been discussed for the optimal water quality monitering network. For empirical study, data of two years (2005, 2006) at the 9 sampling sites with the combination of 2 depth levels and 7 important variables related to water quality is collected in Yongdam reservoir. The similarity among sampling sites is measured with Euclidean distances of water quality related variables and they are classified by hierarchical clustering method. The clustered sites are discussed with principal component variables in the view of the geographical characteristics of them and reducing the number of measuring sites. Nine sampling sites are clustered as follows; One cluster of 5, 6, and 7 sampling sites shows the characteristic of low water depth and main stream of water. The sites of 2 and 4 are clustered into the same group by characteristics of hydraulics which come from that of main stream. But their changing pattern of water quality looks like different since the site of 2 is near to dam. The sampling sites of 3, 8, and 9 are individually positioned due to the different tributary.

• Journal of Ecology and Environment
• /
• 제42권4호
• /
• pp.220-227
• /
• 2018

Background: To understand the ecological characteristics of floating mat in which endangered species of Iris laevigata and Menyanthes trifoliata inhabit, we surveyed the vegetation and water environments of a floating mat wetland and examined the relations between ecological characteristics of the mat. Results: Although Phragmites australis and Zizania latifolia were found at all experimental quadrats (n = 61) as the major vegetational components of the floating mat wetland, they showed relatively poor growth performances in terms of shoot height (< 2 m) and biomass production (<$300g/m^2$) compared with those in soil-based wetlands because of oligotrophic water condition. The competitiveness and distribution of P. australis and Z. latifolia seemed to be determined by water level difference by micro-topography rather than water chemistry. Conclusion: P. australis and endangered plant species mainly occurred in the area of relatively shallow water, whereas Z. latifolia and deep-water species such as Scirpus fluviatilis mostly inhabit in the area of deep water on the floating mat. Continuously maintained water level and oligotrophic water condition in the floating mat appeared to be important environments for endangered species such as I. laevigata and M. trifoliata.

• 상하수도학회지
• /
• 제31권1호
• /
• pp.51-62
• /
• 2017

For the asset management of a water pipe network, it would be necessary to understand the extent of the maintenance cost required for the water pipe network for the future. This study would develop a method to draw the optimum cost required for the maintenance of the water pipe network in waterworks facilities to maintain the aim revenue water ratio and to achieve the target revenue water ratio, considering the water service providers' waterworks condition and revenue water ratio comprehensively. This study conducted a survey with 96 water service providers as of the early 2015 and developed models to estimate the optimum maintenance cost of the water pipe network, considering the characteristics of the water service providers. Since the correlation coefficient of all the developed models was higher than 0.95, it turned out that it had significant reliability, which was statistically significant. As a result of applying the developed models to the actual water service providers, it was drawn that increasing revenue water ratio to more than a certain level can reduce the maintenance cost of the water pipe network by a great deal. In other words, it is judged that it would be the most efficient to secure the reliability of waterworks management by increasing the short-term revenue water ratio to more than a certain level and gradually increase the revenue water ratio from the long-term perspective. It is expected that the proposed methodology proposed in this study and the results of the study will be used as a basic research for planning the maintenance of water pipe network or establishing a plan for waterworks facilities asset management.

• 환경위생공학
• /
• 제21권3호
• /
• pp.37-43
• /
• 2006

Recently, needs for reuse of sludge produced from WTP(water treatment plant) have been increased with shortage of landfill sites and difficulties of the treatment and disposal processes. Therefore, Reusing is becoming an Increasingly popular waste management alternative to divert waste from landfills. In order to research the characteristics of WTP sludges, we used the sludges of C WTP which intake the lake Dae-Cheong and the sludges of S WTP which intake Keum river, The specific surface area of C and S WTP sludges were $0.9986m^2/cc\;and\;1.874m^2/cc$, respectively. The gravity was about $2.0{\sim}2.4$ which are scope of peat or loamy clay. The major minerals of C WTP sludges were kaolinite(48.4%), muscovite(19.5%), and quartz(16.7%). Also, muscovite(31.6%), quartz(30.3%), and kaolinite(17.3%) in S WTP sludges were major minerals.

• 한국물환경학회지
• /
• 제21권2호
• /
• pp.184-189
• /
• 2005

Impacts of non-point source pollution on water quality are well known. In this paper, effects of land use, precipitation characteristics, discharge characteristics on non-point source pollutant loadings at urban, agricultural and forestry watersheds were discussed. Rainfall runoffs from fifteen rainfall events were sampled and analysed at two urban watersheds, one rural watershed, and one forestry watershed. EMCs (Event Mean Concentration) were calculated based on monitored flow rates and concentrations. Statistical analysis carried out with runoff loadings and affecting variables indicated that runoff loadings are weakly correlated with the rainfall intensity and the dry days before rainfall events while showed no correlations with rainfall depth nor runoff quantity. By comparing EMCs between study watersheds on log-normal cumulative probability scale, EMCs ranking were in the descending order of urban watershed>agricultural watershed>forestry watershed for SS, TCOD, TN, and TP.

• 설비공학논문집
• /
• 제13권6호
• /
• pp.490-496
• /
• 2001

An experimental study on the behavior of the water hold-up by condensation of a fin-and-tube heat exchanger with regard to the surface characteristics, i.e., contact angle, was conducted. The static and dynamic contact angles were measured, and condensation experiments were conducted. Flow patterns on the fins with different surface characteristics were visualized. Results showed that the static contact angle is proportional to the dynamic contact angle within the range of this study. The water hold-up of the heat exchanger increases as the static or dynamic contact angle of its surfaces increases. Existence of transition of flow patterns was found as the static or dynamic angle increase. Due to the transition in the flow patterns, changes in the gradient of the water hold-up is occurred around the static angle of 8$0^{\circ}C$.

• 산업기술연구
• /
• 제27권B호
• /
• pp.109-114
• /
• 2007

Humic substances generally comprise 30-50% of the dissolved organic carbon in water. They can affect water quality adversely in several ways and they are important from a water treatment perspective due to their role as precursors for the formation of chlorination by-products such as trihalomethanes. The objectives of this research are to investigate the characteristics of organic matter using raw water of Chuncheon area, to isolate the humic substance fractions from natural water samples, and characterize the extracted humic substances. Humic substances were fractionated according to "isolation of IHSS aquatic humic and fulvic acids" using XAD resin adsorption technique. Characteristics of humic substances were analyzed through DOC, $UV_{254}$, $SUVA_{254}$, FT-IR spectra, fluorescence analysis.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2006년도 하계학술발표대회 논문집
• /
• pp.144-149
• /
• 2006

In this study ice making characteristics are experimentally investigated for the ice slurry generating system which is pneumatically operated. The experimentations are conducted under the various test conditions such as chilled water inlet temperature, aqueous solution concentration, flow rate of cooling water, scraper pitch and frequency of cylinder stroke. For the above experimental conditions, ice making characteristics of the slurry ice generating system are evaluated in terms of the overall heat transfer coefficient, heat transfer rate and the amount of slurry ice generation. And the experimental results show that the heat transfer rate of the system increases as the flow rate of cooling water solution increases and the concentration of ethylene glycol and inlet temperature of chilled water decreases.