• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.538-550
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• 2012

This study suggests a general methodology which is designed for assessing RDOC behavior at the catchment scale by coupling properly a series of steam flow and water quality simulation models and actual monitoring data set. The modified TANK model in which a river routing function is incorporated to the conventional one is applied to simulate the long-term daily stream flow data, and the simulated stream flow data is combined with the 7-parameter log-linear model coupled to the minimum variance unbiased estimator to simulate the long-term daily water quality (BOD, COD and TOC) loads. Finally, the regression analysis between the usually monitored water quality data (BOD, COD and TOC) and RDOC is combined with the simulated water quality data to manifest the spatio-temporal variability of RDOC flux behavior at the Korean TMDL catchment scale.

• Environmental Engineering Research
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• v.14 no.4
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• pp.256-260
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• 2009

This study used the extensive monitoring datasets of the Korea Ministry of Environment to examine trends in dissolved organic carbon (DOC) in Han River raw water. To estimate the organic contents of water, we adopted allied parameters such as biochemical oxygen demand (BOD) and chemical oxygen demand (COD) as substitutes for DOC. Spatial and temporal analyses were performed on monthly BOD and COD data from 36 monitoring stations (14 for Main Han River, 7 for North Han River and 15 for South Han River) measured from 1989 to 2007. The results of trend analysis indicated that, on the whole, water quality according to BOD showed a downward trend at more than 67% of monitoring stations (9 for Main Han River, 6 for North Han River and 9 for South Han River). However, the water quality of COD showed an upward trend at more than 78% of monitoring stations (8 for Main Han River, 7 for North Han River and 13 for South Han River). The upward trend of COD contrary to the BOD trend indicates that there has been an increase in recalcitrant organic matter in Han River water that is not detectable by means of BOD.

• Journal of Korean Society on Water Environment
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• v.34 no.5
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• pp.487-493
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• 2018

Urban stormwater runoff is the one of the most extensive causes of deterioration of water quality in streams in urban areas. Especially, in the Suyeong River watershed, non-point sources from urban-residential areas are the most common cause of water pollution. Also, it has been ascertained that BOD and COD as indexes of organic matter, have limitation on management of Suyeong River's water quality. In this study, changes of organic matter properties of Suyeong River from inflow of non-point source during rainfall were investigated. Fractions of organic matters were analyzed using water samples collected at two sites (Suyeong River and Oncheon Stream) during a rain event. Variations of dissolved organic carbon (DOC) concentration by rainfall were similar to flow rate change in the river. Distribution of organic matter fraction according to change of rain duration revealed that while hydrophilic component increased at initial rainfall, the hydrophobic component was similar to change in dissolved organic carbon (DOC) concentration. Also, the relative proportion of hydrophilic components in organic matter in river water increased, due to rainfall. Results of biodegradation of organic matters revealed that decomposition rate of organic matters during rainfall was higher than that of during a non-rainfall event.

• Advances in environmental research
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• v.1 no.3
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• pp.181-189
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• 2012

Trihalomethanes, produced as a result of chlorination of drinking water, are considered a potential health hazard. The trihalomethane formation potential (THMFP) of a raw water source may indicate the maximum trihalomethanes (THMs) that are likely to be produced when chlorine reacts with natural organic matter (NOM) present in the water. A study was conducted to evaluate the THMFP in seven different drinking water sources in the vicinity of Kalpakkam, a rural township, on the east coast of India. Water from seven stations were analysed for THMFP. THMFP was compared with surrogate parameters such as dissolved organic carbon (DOC), ultraviolet absorbance ($UV_{254}$) and bromide. The data showed that THMFP was high in water from open wells as compared to closed bore wells, possibly due to more photosynthetic activity. Proximity to sea, and consequently the levels of bromide, was an important factor that influenced THM formation. THM surrogate parameters showed good correlation with THMFP.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.205-210
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• 2018

In this study, we investigated coagulants such as polyaluminum chloride (PACl) and ferric chloride ($FeCl_3$) and the combination of a coagulant and powdered activated carbon (PAC) for the removal of dissolved organic matter (DOM) from fish processing effluent to reduce membrane fouling in microfiltration. The efficiency of each pretreatment was investigated through analyses of dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm ($UVA_{254}$). Membrane flux and silt density index (SDI) analyses were performed to evaluate membrane fouling; molecular weight distributions (MWD) and fluorescence excitation-emission matrix (FEEM) spectroscopy were analyzed to assess DOM characteristics. The results demonstrated that $FeCl_3$ exhibited higher DOC and $UVA_{254}$ removals than PACl for food processing effluent and a combination of $FeCl_3$ and PAC provided comparatively better results than simple $FeCl_3$ coagulation for the removal of DOM from fish processing effluent. This study suggests that membrane fouling could be minimized by proper pretreatment of food processing effluent using a combination of coagulation ($FeCl_3$) and adsorption (PAC). Analyses of MWD and FEEM revealed that the combination of $FeCl_3$ and PAC was more efficient at removing hydrophobic and small-sized DOM.

• 한국지구과학회:학술대회논문집
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• 2005.02a
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• pp.115-125
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• 2005

Carbon isotopic composition of a stream (Odaecheon Stream) monitored over 7 months from July 2004 to January 2005 in Gangweon Province ranges from -9.24 to -4.69‰. Strong negative correlation between ${\delta}^{13}C_{DIC}$ and water temperature suggests that temperature is a dominant factor controlling ${\delta}^{13}C_{DIC}$ in the Odaecheon Stream. The variation pattern of ${\delta}^{13}C_{DIC}$ was thought to be caused by fractionation of C isotope between stream water and atmosphere and more fractionation at reduced temperature. More fractionation of C isotope between stream water and atmosphere at reduced temperature resulted in increase of ${\delta}^{13}C_{DIC}$ of stream water in winter compared to summer. Photosynthesis and respiration of aqueous biota seem to affect little in ${\delta}^{13}C_{DIC}$ as indicated by little variation of dissolved oxygen and reverse variation pattern of Eh in the stream and scarce aqueous biota in stream water. pH seems to be controlled by $CO_2{2}$ exchange between stream water and atmosphere. During summer more $CO_2{2}$ exchange between stream water and atmosphere resulted in decrease in pH value.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.234-236
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• 2018

기후변화는 더 이상 피할 수 없는 매우 중요한 문제다. 온실가스 중 큰 비중을 차지하는 이산화탄소 배출을 억제하거나 제거하기 위한 많은 연구들이 진행되고 있다. 최근에는 CCS 중 하나인 지중저장(underground storage)의 대안으로 해양에 이산화탄소를 저장하는 기술인 AWL(Accelerated Weathering of Limestone)을 이용한 해양저장(ocean storage)에 대한 연구가 진행되고 있다. AWL은 이산화탄소를 중탄산이온 형태의 농축수로 만들어 해양에 방류하여 희석 저장시키는 방법으로, 대기 중 재방출이 거의 발생하지 않고 배출된 농축수는 해양의 알칼리도를 높여 해양산성화를 방지할 수 있는 장점이 있다. 금회 연구는 AWL에 의한 방법 중 중탄산이온 농축수의 해양방류 시 이산화탄소 등을 포함하는 용존 무기탄소(DIC, Dissolved Inorganic Carbon)의 거동특성을 파악하기 위한 목적으로 수행하였다. 연구대상 해역은 충분한 수심과 작업효율성이 확보되는 울릉도 부근으로 설정하였으며, 거동특성을 파악하기 위하여 표층방류(surface discharge)와 수중방류(submerged discharge)에 의한 물질확산을 계산할 수 있는 CORMIX모형을 채택하였다. 실험결과, 방류 시점으로부터의 희석률을 고려했을 때, 표층방류 시나리오가 농축수 방류에 가장 적합한 방식이라고 사료된다.

• Journal of the Korean Society for Heat Treatment
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• v.26 no.6
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• pp.300-305
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• 2013

The effects of solute carbon atoms on the thermal expansion coefficients of ferrite and austenite as well as austenitization behavior were investigated by comparing carbon-free ferrite and carbon-containing ferrite. The thermal expansion coefficients and austenitization start and finish temperatures were measured using a dilatometer. Solute carbon atoms at elevated temperatures above the cementite dissolution temperature (650 K) decreased the thermal expansion coefficients of both ferrite and austenite. In addition, minute amount of carbon atoms dissolved in ferrite stimulated austenite nucleation during continuous heating, resulting in the lower starting temperature of austenitization.

• Journal of Korean Society on Water Environment
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• v.28 no.3
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• pp.479-482
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• 2012

Membrane process has been one of the widely applied wastewater treatment options, especially in field. However, one of the tricky issues in the process is to treat concentrates generated from reverse osmosis (RO) system in a manner of saving cost with maximum efficiency for treating a wide range of contaminants. Stimulated with the challenging issues, we have conducted a series of experimental studies in the evaluation for removing organics and nutrients using activated carbon. Results indicated that while powdered activated carbon (PAC) efficiently removed organics and the extent of removal was proportional to the PAC dosage, little removal of nitrogen and phosphorus was observed despite increasing the PAC dose. Interestingly, applying PAC was superior in removing organics than using granular activated carbon (GAC). These results suggest smaller particle size with higher surface area could provide greater chemical reactivity in removing organics.

• Journal of the Korean institute of surface engineering
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• v.52 no.6
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• pp.326-333
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• 2019

The microporous carbon derived from PVDC-resin by a simple heat-treatment under an inert atmosphere exhibits a reasonable specific capacitance for a supercapacitor's electrode. However, the capacitance was rapidly decreased at high charge/discharge rate. The micropores present in an electrode surface hinder the entrance of an electrolyte ion onto the entire surface. To induce the meso-sized pores during the carbonization of PVDC-resin, Mg(OH)₂ was utilized as a hard template. The porous carbon made from the mixture of PVD-Cresin and Mg(OH)₂ include mesopores as well as micropores. The induced mesopores does not homogeneously distributed on the entire surface of the synthesized carbon. The PVDC-resin and Mg(OH)₂ are dissolved in the dimethylformamide for the hard template to evolve the pores on the synthesized carbon uniformly. The carbon made from PVDC-resin with solvent and a hard template contains mostly mesopores resulting in the high power performance. The reduced amount of solvent in the precursor derives the carbon with high specific surface area and high power density.