• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.289-299
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• 2011

We studied the characteristics of pollutant concentrations in 9 streams that flow into Shihwa Lake in order to provide the scientific data for effective implementation of total pollution loads management system (TPLMS) of the Lake. Suspended solid (SS), chemical oxygen demand (COD), dissolved nutrients ($NO_2$, $NO_3$, $NH_4$, $PO_4$ and $SiO_2$), total phosphorus (TP) and total nitrogen (TN) in stream water from industrial complexes, urban and agricultural regions were determined. Pollutant concentrations in December were higher than that in other sampling periods. COD concentration from industrial complex region with average of 12.6 mg/L was 2 times higher those from urban region (6.6 mg/L) and agricultural region (5.9 mg/L). TP concentration from industrial region also showed higher concentration than other regions. TN concentration in stream water was 5.89 mg/L for industrial region, 3.02 mg/L for urban region and 5.27 mg/L for agricultural region, respectively, suggesting inflow of TN due to fertilizer usage in agricultural field. Relative percentage of nitrogen compounds in TN follows the sequence: $NH_4$ (35.1%) > $NO_2$ (20.0%) > DON (22.8%) > PON (8.9%) > $NO_2$ (3.2%). Concentrations of dissolved nutrients, TP and TN in stream water were 3.2~37.2 times higher than that in Shihwa Lake seawater, therefore large amount of pollutants may be directly entered into Shihwa Lake without any treatment. For Gunja stream of industrial region, pollutants at midstream showed relatively higher concentration compared to upstream and downstream. It is necessary to manage the illegal discharging of sewage and waste water. Our results provide valuable informations on the estimation and reduction of total pollutant loads in the process of establishing adequately strategic and implemental plan of Shihwa Lake TPLMS.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.6
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• pp.743-752
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• 2009

One of the major problems associated with operation of domestic sewer lines involves hydraulic problems such as insufficient conveyance capacity, exceeding maximum velocity, and deficiency of minimum velocity. It has also been pointed out that influent concentration lower than design concentration of pollutants, which is mainly caused by unidentified inflow and infiltration, degrades the operational efficiency of many sewage treatment plants (STPs). A computer-added analysis method supporting a coupled simulation of sewage quality and quantity is essentially required to evaluate the status of existing STPs and to improve their efficiency by a proper sewer rehabilitation work. In this study, dynamic water quality simulations were conducted using MOUSE TRAP to investigate the principal parameters that governs the changes of BOD, ${NH_4}^+$, and ${PO_4}^{3-}$3- concentrations within the sewer networks based on data acquired through on-site and laboratory measurements. The BOD, ${NH_4}^+$ and ${PO_4}^{3-}$3- concentrations estimated by MOUSE TRAP was lower than theoretical pollution loads because of sedimentation and decomposition in the sewer. The results revealed that sedimentation is a most important factor than other biological reactions in decreasing pollutant load in the sewers of C-city. The sensitivity analysis of parameters pertaining to water quality changes indicated that the effect of the BOD decay rate, the initial DO concentration, the half-saturation coefficient of dissolved BOD, and the initial sediment depth is marginal. However, the influence of settling rate and temperature is relatively high because sedimentation and precipitation, rather than biological degradation, are dominant processes that affect water quality in the study sewer systems.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.11
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• pp.1623-1627
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• 2005

Heavy metal pollution has become a serious health concern in recent years. Dogs are a very good indicator of the pollution load on the environment. They share people's environment and are exposed to the action of the same pollutants. This study estimated the heavy metal contents in the serum of dogs in domestic districts, and assessed the age, sex, feeding habits, living area, breeding environment and smoking habit of the owners. The findings suggest that dogs can be used to monitor the environmental quality of heavy metals. The mean concentrations of heavy metals in the dog serum from 204 samples (108 male and 96 female) were 0.22${\pm}$0.01 $\mu$g/ml, 0.24${\pm}$0.04 $\mu$g/ml, 0.61${\pm}$0.08 $\mu$g/ml, and 0.50${\pm}$0.06 $\mu$g/ml (for Cd, Hg, Pb, and Cr), respectively. Concentrations of Pb, Cd, Hg, and Cr in the dog serum were higher in Yeongnam including Ulsan, and Seoul higher than those of Chungchong and Honam, especially Pb concentration, which was significantly higher (p<0.01). Concentrations of Cd, Hg, Pb, and Cr in serum, were increased by age (p<0.05). When commercial pet food was provided to dogs, Cd and Cr concentrations were significantly higher in dog serum than dogs fed a human diet (p<0.01 in Cd and p<0.05 in Cr). Heavy metal concentrations of dogs owned by smoking owners, were higher than non-smoking owners although there was no significant difference.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.413-418
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• 2012

A modified VIStA (Vortex Inertial Staged Air) burner has been developed and applied to a once-through type boiler. The secondary air is supplied through a swirler instead of nozzles, which stabilizes the flame and reduces carbon monoxide (CO) emissions. However, the modification increases the emission of nitrogen oxides (NOx). To balance emissions of the two pollutants, a divided flame was adopted. An air damper was installed to control the distribution of air to each combustion chamber, and three types of flame dividers were studied. The effects of the air-fuel ratio and combustion load on the NOx formation were investigated. The divided flame was found to reduce the NOx emission up to 25%, while keeping the CO to less than 10 ppm.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.5
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• pp.586-594
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• 2012

A future type ship power system requires both economic and eco-friendliness. That is, this should be reduced the discharge quantity of air pollutants and green-house gases as well as have high energy efficiency. Recently, gas turbines have been realized a lot of technical development in terms of efficiency and safety, and are widening the example of their adoption to a GT/ST hybrid system in a power plant as well as an aviation use. This paper reviewed the performance characteristics of a GT/ST hybrid system of several ten MW class, not large capacity, with a simulation in order to evaluate the possibility of a GT/ST hybrid system for ships. The reviewed GT/ST hybrid system has maximum 49 % efficiency, has the highest efficiency point for TIT, and has a 70~75 % and 25~30 % load ratio for a gas turbine and a steam turbine respectively.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.1
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• pp.39-48
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• 2008

This study was carried out to investigate the characteristics of the pollutant discharge from non-point source and to estimate the unit loads of the pollutant discharge from the upper watershed of Seomjin Dam during rainy season. The upper watershed of Seomjin Dam is located in the middle of Jeonbuk province is formed two tributaries mainly. A sub-branch stream of those tributaries is Imsil stream of which flow rate is about 13% of the main stream of Seomjin reservoir normally. On the basis of measurement result in this study, the water quality of Imsil stream was fluctuated highly and the quantity of measured pollutant discharge was higher than the value calculated with the proportion of flow rate during dry season. On the contrary, during rainy season the mean values of flow rate and water quality were higher than the quartile according to the statistical analysis. That means rainfall can influence strongly on the water quality of the upper watershed of Seomjin reservoir. Among the several criteria of water quality, SS discharge was most sensitive to the flow rate variation of stream, which was fluctuated in proportion of rainfall, basically. It was evaluated the event mean concentration (EMC) of non-point source pollutants depending on rainfall events as well. Though the pollutant discharge unit of Imsil stream was lower than the main stream of Seomjin reservoir, the EMC value of Imsil stream was higher than the main stream of Seomjin reservoir.

• Journal of Wetlands Research
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• v.11 no.3
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• pp.9-19
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• 2009

This research addressed nonpoint source (NPS) pollution characteristics in a reclaimed rice paddy field. The paddy has an area of around 2,998 ha and is divided as two sub-watersheds, whose areas are 1,181 ha and 1,817 ha, respectively. Monitoring of hydrologic runoff and NPS pollution was undertaken during three-month period from June to August, 2008. Totally, three sampling trips were made when rainfall depth were 66.0 mm, 23.5 mm, and 23.0 mm, respectively. Generally pollution load increased with the heavier cultivation activity in Korea. Exported pollutants from the rice paddy, including TSS, TN and TP, have same levels as forest discharge. Organic nitrogen is main pattern but it mainly exists in the forms of dissolved organic nitrogen (DON). For phosphorus, dissolved inorganic phosphorus (DIP) takes the main part although part of them is associated with fine particles. This is different compared with other watersheds, where particles-associated phosphorus is the main form.

• Journal of Power System Engineering
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• v.19 no.2
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• pp.49-56
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• 2015

As an alternative fuel that can be used in SI engine, LPG is one of clean fuels with larger H/C ratio compared to gasoline, low $CO_2$ emission, and small amount of pollutants such as sulfur compounds. When LPG is used in spark ignition engine, volumetric efficiency of the engine can be improved and pumping loss can be reduced by performing direct injection into the combustion chamber instead of port fuel injection. LPG-DI engine allows for lean combustion and stratified combustion under low load. In case of stratified combustion, air fuel ratio can be greatly increased compared to theoretic mixture ratio combustion. Improved thermal efficiency of the engine and reduced pumping loss can be expected from stratified combustion. Accordingly in this study, an experimental apparatus for visualization was designed and manufactured to study the combustion process of LPG after injection and ignition, intended to examine ignition probability and combustion characteristics of spark ignition direct injection(SIDI) LPG fuel. Ambient pressure, ambient temperature and fuel injection pressure were found as important variables that affect ignition probability and flame propagation characteristics of LPG-air mixture. Also, it was verified that the injected LPG fuel can be directly ignited by spark plug under appropriate ambient conditions.

• Journal of Korea Water Resources Association
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• v.37 no.9
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• pp.719-727
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• 2004

Water quality models can be applied to manage the regional water quality problems and to estimate the target and allowable pollution load in watershed effectively. The optimization of state variables in the given water quality model Is necessary to build up more effective model. The least-squares method is applied to fit field observations in QUAL2E developed by U.S. EPA, which is most widely used one in the world to simulate the stream water quality, and the optimization model with constraints is constructed to estimate the parameters. The objective function of the optimization model is solved by Solver in Microsoft Excel and Monte Carlo simulation is conducted to know the influence of parameter in conventional pollutants. It is found that this technique is easily implemented and rapidly convergent computational procedure to calibrate the parameters after appling this approach in Anyang stream located in Kyonggi province mainly.

• Environmental Engineering Research
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• v.13 no.4
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• pp.184-191
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• 2008

Long term monitoring was conducted to investigate a surface runoff of pollution from urban highway. The monitoring data was collected for 18 rainfall events and was used to correlate pollution load to various parameters, such as rainfall intensity, antecedent dry days and total discharge flow. Runoff coefficient and seasonal variation were also evaluated. The mean runoff coefficient of the highway was 0.823(range; $0.4687{\sim}0.9884$), and wash-off ratio for $COD_{Mn}$ and SS loads was 72.6% and 64.3%, respectively. For the initial rainfall event, the runoff EMC of $COD_{Mn}$ was high in summer and the EMC of SS was high in autumn season. However the seasonal variation of T-N and T-P was not significant. The discharged $COD_{Mn}$-EMC was $147.6\;mg/L{\sim}9.0\;mg/L$ on the generated $COD_{Mn}$-EMC of $98.8\;mg/L{\sim}8.9\;mg/L$. While the generated EMC of SS was in $285.7\;mg/L{\sim}20.0\;mg/L$ and its discharged EMC was in $190.4\;mg/L{\sim}8.0\;mg/L$. EMC of pollutants was not directly related to the first flush rainfall intensity and the antecedent dry days. But the correlation was relatively high between EMC and cumulative runoff flow volume. The trend of EMC was reduced with the cumulative runoff flow volume.