• Environmental Analysis Health and Toxicology
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• v.14 no.1_2
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• pp.35-43
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• 1999

A number of disinfection by-products (DBPs) are formed as a result of the addition of chlorine into the public water supply and some of them have been suggested to cause adverse health effects on humans. However, the estimation of human ingestion exposure to each DBP has been performed simply by multiplying the concentration of a chemical in the cold tap water by the volume of water consumed during a given period of time. However, a questionnaire concerning water consumptions administered to sixty people residing in Chunchon showed that the volume of tap water consumed accounted for approximately 70% of the total volume of water consumed and that of heated water represented approximately 94% of tap water ingested. Heating durations for water-containing foods (e. g., soups and pot stews) and heated beverages (e. g., barley tea) were grouped into 10, 20, 30, and 35 minutes. Based on these time frames, an aluminum pot containing one liter of tap water was heated for the above respective time periods using a gas range to determine the variations of the concentrations of individual DBPs by heating. The pH and total residual chlorine were measured before and after heating. Collected water samples were carried to the laboratory and analyzed for eight DBPs and total organic carbon. Chloroform, bromodichloromethane, chloral hydrate, 1, 2-dichloro-2-propanone, 1, 1, 1-trichloropropanone, and dichloroacetonitrile were not detected following heating for 10 minutes and longer. The concentration of dichloroacetic acid (DCAA) was elevated with heating duration, resulting in the averages of 2.0, 3.1, 4.7, and 12 times the initial concentration, respectively, for 10, 20, 30, and 35 minute heating periods. On the other hand, the concentration of trichloroacetic acid (TCAA) decreased with heating duration, with 0.65, 0.40, 0.34, and 0.19 times lower than the initial concentration. Therefore, it is suggested that ingestion exposure to DCAA increases with heating duration but that ingestion exposure to TCAA decreases. In addition, while the amount of DCAA was elevated at the initial time periods (10 or 20 minutes) and then slowly decreased, that of TCAA was rapidly decreased. In conclusion, water-heating processes during cooking influence the concentrations of individual DBPs in the tap water, with lower levels for volatile DBPs and TCAA, and higher levels for DCAA. Therefore, concentration change needs to be taken into consideration in the estimation of human ingestion exposure to DBPs.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.194-197
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• 2008

We measured the efficiency and flue gas concentration of a 90kW woodchip boiler which is for heating water of lodging. At nominal operating condition, the fuel, woodchip is fed into the boiler at a rate of 22.6 kg/h. In order to determine the efficiency of the boiler, we measured the water flow rate, woodchip flow rate, heating value and water content of woodchip, temperature of inlet and outlet of heating water. The results of test show that the power output of the woodchip boiler is 90.0 kW(77,400 kcal/h) and the thermal efficiency of the boiler is 88.5%. By using a gas analyser, flue gas concentrations are measured. The results show that O2 in the flue gas is 10.2%, CO concentration is 393 ppm and NOx concentration is 74 ppm.

• Environmental Engineering Research
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• v.17 no.3
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• pp.151-156
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• 2012

This research described the magnetic method for the rapid removal of green algae in water. We modified the pH, cation concentration, and magnetic powder concentration to discover the best removal performance. In order to rapidly remove green algae from water, we added magnetic powder and chitosan into algae water to make a magnetic substance and this was extracted by a strong neodymium magnet. The optimized conditions were pH of 6.5-7.5, chitosan concentration of 10 mg/L, and magnetite powder concentration of less than 0.05%. A higher removing rate was observed when a higher amount of magnetite or chitosan was used, but the total amounts of phosphorus or nitrogen were not decreased.

• Corrosion Science and Technology
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• v.10 no.4
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• pp.151-155
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• 2011

The iron oxide particles could be resulted from the corrosion of the circulating water system of a power plant. Because it may be one of the trouble materials which affect the power generation efficiency due to the deposition on steam generator tube and turbine blade, the continuous observation of its concentration is very important. The laser induced break-down detection (LIBD) technology was applied to monitor continuously the concentration of corrosion products with the detection limit of ppb level. The measurement system consists of a Nd:YAG pulsed laser, a polarizing beam splitter, a flow-type sample cell, an acoustic emission sensor, a high speed data acquisition board, a personal computer, etc.. The performance test results confirmed that this technology can be effective to monitor the corrosion product concentration of the circulating water system of a power plant.

• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.166-171
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• 2006

The objectives of the present paper were to investigate the concentration of total coliform in wastewater effluents and the effect of water chemical and physical characters in it. The most correlated parameter with total coliform was COD. It means that the wastewater treatment efficient effects on total coliform concentration. And we developed predictive model for the total coliform concentration. The estimated parameters for model were COD, temperature, nitrite, chloride, Mn and regression model equation was determined; log (Total Coli.) = 1.861+0.065[COD]+0.038[temperature]-0.0004[$Cl^-$]+3.697[Mn]-0.32 [$NO_2-N$] The developed model provided very strong correlation ($R^2:0.82$) between total coliform and regression equation. The parameters having high sensitivity were COD and temperature. So the study indicated that if the temperature and COD of wastewater effluent were known, we would estimate the concentration of total coliform and decide the most effective usage of chlorine.

• Korean Journal of Remote Sensing
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• v.16 no.4
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• pp.315-325
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• 2000

Observations were made to validate ocean color algorithms in the Ulleung Basin, East Sea in May 2000. Small scale and meso-scale surveys were conducted for the validation of ocean color products (nLw: normalized water-leaving radiance and chlorophyll concentration). There were discrepancies between SeaWiFS and in situ nLw showing the current aerosol models of standard SeaWiFS processing software are less than adequate (Gordon and Wang, 1994). Applying the standard SeaWiFS in-water algorithm resulted in an overestimation of chlorophyll concentration. This is because that CDOM absorption was higher than the estimated chlorophyll absorption. TSS concentration was also high. Therefore, the study region deviated from Case 1 waters. The source of these materials seems to be the entrainment of coastal water by the Tsushima Warm Current. Study of the bio-optical properties in other season is desirable.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.21-31
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• 2000

We investigated seasonal variation of microalgal assemblages, sea water temperature, salinity and suspended solid and the parameters measured daily from January 1998 to October 1999 at a nearshore shallow-water in Marian Cove, Maxwell Bay, King George Island, the Antarctic. Annual mean surface water temperature was -0.3$0^{\circ}C$ and the highest water temperature was 4.53$^{\circ}C$ (22 January 1999) and the lowest water temperature was -2.07$^{\circ}C$ (23 August 1998). Annual mean salinity was 33.38 psu, ranging from 42.80 psu (6 January 1999) to 19.50 psu (6 June 1999). Annual mean suspended solid (SS) during two years was 34.14 mgㆍ1$^{-1}$, ranging from 60.62 mgㆍ1$^{-1}$(7 March 1998) to 12.90 mgㆍ1$^{-1}$ (26 December 1998). Chlorophyll $\alpha$ (Chl $\alpha$) concentrations were measured in order to know seasonal variations of microalgae in the surface seawater. Annual mean of total Chl a concentration was 0.55$\mu\textrm{g}$ㆍ1$^{-1}$, the highest Chl $\alpha$ concentration (12.16$\mu\textrm{g}$ㆍ1$^{-1}$) appeared in 4 October 1998, the lowest Chl $\alpha$ concentration appeared 0.19$\mu\textrm{g}$ㆍ1$^{-1}$, Monthly mean total Chl $\alpha$ concentration was high in October 1998 (1.32$\mu\textrm{g}$ㆍ1$^{-1}$) and low in July on 1998 (0.28$\mu\textrm{g}$ㆍ1$^{-1}$). Annual mean nano-sized Chl $\alpha$ concentration was 0.40$\mu\textrm{g}$ㆍ1$^{-1}$, monthly mean nano -sized Chl $\alpha$ concentration was high in November 1998 (0.90$\mu\textrm{g}$ㆍ1$^{-1}$), and low in July 1999 (0.22$\mu\textrm{g}$ㆍ1$^{-1}$). Annual mean micro-sized Chl $\alpha$ concentration was 0.15$\mu\textrm{g}$ㆍ1$^{-1}$ monthly mean micro-sized Chl $\alpha$ concentration was high in October 1998 (0.81$\mu\textrm{g}$ㆍ1$^{-1}$), and low July 1998, January, February and September 1999 (0.05$\mu\textrm{g}$ㆍ1$^{-1}$). More than 65% of total Chl $\alpha$ was concentrated during spring and summer time between October and March. Microalgal variation appeared to be due to physical factors of seawater in the Antarctic nearshore from 1998 to 1999. The reason why micro-sized Chl $\alpha$ did not increase during austral summer was the bay had been frozen by decrease of water temperature. We think that total microalgal abundance was decreased because the summer microalgal abundance was determined by variation of water temperature during winter season. [Chl $\alpha$ concentration, Microalgal assembalges, Seasonal variation, the Antarctic nearshore].

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1093-1102
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• 2009

This study was focused on analyse Nonpoint source characteristics from Flat slope field and Steep slope field. We performed Storm-water monitering for obtain flow data and concentration data. Totally, eleven times Event was occurred. We calculated EMC(Event Mean Concentration) and Pollutants Loads using data we obtained. As a result, steep slope field has more discharge than flat field. SS value, one of the water quality contents, has largest variation and T-N has least variation. There is runoff differences even though events has same rainfall. We assume that not only amount of Rainfall, but also Rainfall Duration Times, Intensity, Number of Previous Non-precipitation days can affect to Run-off.

• Journal of environmental and Sanitary engineering
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• v.8 no.2
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• pp.155-168
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• 1993

The chemical components of rain water and aerosol in Bulkwang of Seoul and Yang-Paying of Kyunggi-do were compared in order to investigate that pollutants at urban area influences rain water and aerosol component. The following is the result of this study. 1) The pH of rain water was shown 4.82 at urban area and 5.69 at suburban area. 2) The mean concentration of $SO_4^{2-}$ within rain water at suburban was nearly the same at urban area but the mean concentration of $Na^{+},Ca^{2+},Mg^{2+}$ and $NH_4^{2+}$ at suburban area was higher than the corresponding levels at urban area. 3) The ion component of aerosol at suburban was shown 68% of that at urban area. This study proved that the concentration of rain water and aerosol component was under the influence of movement of air current.

• Journal of the Korean Ceramic Society
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• v.28 no.2
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• pp.167-175
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• 1991

In synthesizing hydrated zirconia powder by hydrolysis of Zr-alkoxides using ethanol as mutual solvent, three experimental parameters, namely, concentration of alkoxides and hydrolysis water and addition rate of hydrolysis water were varied systematically. Spherical, monodispersed, nonagglomerated and submicrometer sized powders were prepared at 0.3 M of Zr(n-OPr)4 and 0.05M of Zr(n-OBu)4 with wide ranges of hydrolysis water conditions i.e. 0.5-2.0M concentration and 1-20ml/min addition rate. During the hydrolsis, careful attention have to be paid to maintain homogeneous reaction by controlling the agitation of the reactant and the addition of the hydrolysis water. For more improved condition of monodispersity it was found that the key point is to shorten the self-nucleation time within several seconds as rapid as possible. In both alkoxides system, with higher concentration of alkoxide and hydrolysis water and with slow addition rate of hydrolysis water, hydrated zirconia powders synthesized showed tendency to fall in worse powder conditions.