• Journal of Korean Society on Water Environment
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• v.25 no.5
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• pp.697-703
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• 2009

In this study, changes in the composition of dissolved organic carbon (DOC) were investigated using water samples collected at a downstream site of the Namhan River near the Lake Paldang ($N37^{\circ}24^{\prime}05.33^{{\prime}{\prime}}E127^{\circ}32^{\prime}25.01^{{\prime}{\prime}}$) during a heavy rain event from July 23 to July 28, 2008. The DOC concentrations varied from 1.68 to 3.18 mg/L with the maxium value at a peak of the river water level. Each DOC sample was fractionated into three compositions including hydrophilic (Hi), hydrophobic acid (HoA) and hydrophobic neutral (HoN) fractions. The results showed that HoA was most abundant fractions, constituting 47.2~56.5% of DOC. Refractory dissolved organic carbon (R-DOC) contents were also determined by measuring the DOC concentration after 28-day dark incubation of the samples. R-DOC content was in the range from 83 to 99% of DOC and it was significantly correlated with HoA contents (r = 0.91, p<0.005), while it did not exhibit such a good correlation with the fractions of Hi and HoN (p>0.02). Our results suggest that the HoA, which is associated with humic substances, may be a major composition of refractory organic matters in rivers during storm events.

• Journal of Korean Society on Water Environment
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• v.33 no.5
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• pp.580-586
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• 2017

The fractionation characteristics of organic matter were investigated in inflow and effluent of each other pollution sources and river. While the DOC/TOC ratio in the influent of public sewage treatment plant and livestock disposal facilities was above 0.58, the POC/TOC ratio of human livestock Night soil treatment plant and stormwater runoff was more than 0.7. The TOC removal efficiency of public sewage treatment plant and human livestock Night soil treatment plant were 88.5 % and 99.6 %, respectively. Although the concentration distribution of organic matter pollution most of total organic carbon (TOC) in effluent of pollution sources accounted for dissolved organic carbon (DOC) type (DOC/TOC ratio >0.89) and Refractory-DOC (RDOC)/TOC ratio was higher (>0.65). The fractionation characteristics of organic matter in river were similar with that of sewage treatment plant and TOC concentration showed the positive correlation with DOC ($r^2=0.93$) and RDOC ($r^2=0.89$) concentration. The decay rate of Labile DOC (LDOC) (avg. $0.128day^{-1}$) was higher than labile particulate organic carbon (LPOC) ($0.082day^{-1}$), while that of DOC ($0.008day^{-1}$) was lower than POC ($0.039day^{-1}$) (paired t-test, p < 0.001, n = 5). These study results suggested that it should consider important both TOC and DOC as the target indicator to control refractory organic matter in pollution sources.

• Journal of Korea Trade
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• v.25 no.1
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• pp.89-111
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• 2021

Purpose - The U.S. Trade Preference Expansion Act (TPEA) of 2015 enables the US Department of Commerce (DOC) to inflate dumping margin when the particular market situation (PMS) exists in the exporter's home market. DOC applied PMS provisions to the steel products from Korea. This paper analyzes whether DOC's calculation by using the regression analysis is consistent with WTO rules. Design/methodology - This paper analyzes the PMS application in law and regression analysis that extends the data period from 10 years to 18 years using the same economic model with DOC, and changes the country group according to the quantities of steelmaking capacity. Findings - Results show that DOC's argument conflating the sales-based with cost-based PMS designed to inflate dumping margins might not be consistent with WTO Antidumping Agreement Article 2.2 and 2.2.1.1 in which costs shall normally be calculated on the basis of records kept by the exporter, providing generally accepted accounting principles and reasonably reflection of the costs and PMS that exists in the Korean steel product markets. Even if it will be consistent, DOC's calculated margin by the regression analysis using a 10-year data is a big gap (5 times) compared with an 18-year data projection and different countries' data through the same methodology, which is a huge gap of regression coefficient. It means that dumping margin would be very wide range from 7.8% to 38.54% and unstable to calculate. Inflating dumping margin by DOC using regression analysis would not only be inconsistent with WTO rules, but also projection result is unreliable. Originality/value - Literature papers have mainly analyzed WTO law itself. This paper however, would be the first attempt to analyze the DOC's new way of dumping margin calculation in both manners of law and an empirical methodology perspective at the same time.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.5
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• pp.411-417
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• 2002

The purpose of this study is to evaluate the emission reduction characteristics depending on the formation of the catalyst which influences the development of the diesel oxidation catalyst (DOC) suitable for small-sized diesel engines. We also attempted to suggest the feasibility of it as an after-treatment device. The reduction efficiency of DOC for CO and HC was proportional to the contents of precious metals, and the particulate matter (PM) has been reduced as much as 53∼59%. The reduction rate of soluble organic fraction (SOF) by DOC attachment revealed 100%. The composition of sulfate in PM increased from 3%, 7∼11% by installation of DOC. It is described that increase of sulfate contributed to the production of PM. This result also showed that the SOF and sulfate have trade-off relationship.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.1
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• pp.52-58
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• 2004

To develop a low emission engine, it is necessary to obtain some better quality of automotive fuels. Sulfur in fuel is transformed to sulfate-laden PM as DOC is applied. Therefore, it necessary to provide low sulfur fuels before DOC is applied. According to the specification of test fuels, flash point, distillation 90％, cetane index are improved but viscosity is decreased in the process of desulfurization. Excessively reduced sulfur may cause to decrease lubricity of fuel and engine performance in fuel injection system. Therefore, this research was emphasized how the application of Bio-diesel affects on the emission characteristics and engine performance under the circumstance of ULSD and DOC.

• Journal of environmental and Sanitary engineering
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• v.19 no.2
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• pp.1-6
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• 2004

In Bok-Jeong water treatment plant, chlorination is the only technique used for disinfection of drinking water. This disinfecting treatment leads to the formation of trihalomethanes (THMs). This study was carried out to investigate the possibility of improving removal efficiency of THM precursor in the conventional water treatment processes by $TiO_2$ photocatalytic oxidation. Removal efficiencies of DOC, $UV_{254}$, THMFP were low in the conventional water treatment processes. With application of $TiO_2$ photocatalyst, DOC, $UV_{254}$, THMFP were reduced more effectively. As the $TiO_2$ photocatalytic reaction time increased, the removal efficiencies of DOC, $UV_{254}$, THMFP were increased. The $TiO_2$ photocatalytic removal efficiencies of DOC, $UV_{254}$, THMFP were increased with increasing $TiO_2$ dosage. However, over 0.6g/l of $TiO_2$ dosage, the efficiency reached a plateau.

• Journal of Korean Society on Water Environment
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• v.20 no.5
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• pp.447-451
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• 2004

The various pretreatment processes were evaluated to remove organic pollutants of weathered oil contaminated seawater(WOCS) for reverse osmosis desalination process, Biodegradation, coagulation, ultrafiltration, advanced oxidation processes and granular activated carbon filtration were used to evaluate the potential of organic pollutants removal in WOCS. Dissolved Organic Carbon(DOC) was almost not removed by biodegradation in WOCS. DOC was removed by 25% and 10% with the addition of $FeCl_3$ and PAC in WOCS, respectively. The removal efficiency using ultrafiltration(WOCS 500) was about 20% of DOC and 40% of $E_{260}$, respectively. In AOP application of WOCS, the removal of organic materials was improved up to 60% by the combination of $UV/O_3$ compared to UV process. However, 98% of DOC in woes could be removed by granular activated carbon filtration. It is revealed that activated carbon filtration is the best process for the pretratment of DOC removal.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.16-21
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• 1999

The diesel vehicle is relatively superior to gasoline vehicle on the fuel consumption, durability and combustion efficiency. However, exhaust emission from diesel vehicle are known to be harmful to human health and environment. The treatment technologies for the diesel exhaust gases are classified as replacement of fuel, quality control of diesel fuel, improvement of engine and aftertreatment system. The most effective for the treatment technology is known to be aftertreatment system, and this research is continuously conducted by many groups. The DOC system has many advantages of reducing particulates and harmful gaseous substances such as CO. HC. Moreover, it is simple in device structure, relatively low cost, and easy to install witout retrofitting the vehicle. In this study, experiment were conducted to analyze the effects on factors of oxidation characteristics and conversion efficiency of DOC. In experiment, test was conducted to estimate engine emission in 11,000cc diesel engine which was equipped with DOC.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.3
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• pp.261-266
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• 1998

Recently, air pollution is increased according to increase of vehicle. So many countries are studying about DOC for diesel emission decrease. However, there are many difficulty in applying to DOC . In this study, SOx exhaust gas equipped with DOC was studied and we obtained several test results as following. First, in diesel oxidation catalyst, additives such as Pt is very effective for 503 and sulfate. Second, the oxidative activity for 502 has decreased to add such as Pt and the decrease of 502 is effect for the reduction of PM in high temperature . And finally, in high temperature, concentration of SOx is increased and temperature is affected by process from SOB to 503, whereas engine performance and fuel consumption are not affected by equipped DOC.

• Journal of Korean Society on Water Environment
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• v.27 no.3
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• pp.306-313
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• 2011

In this paper, runoff characteristics of South-Han river watershed in terms of refractory organic matters were investigated. The concentrations of DOC, POC, R-DOC, R-POC in runoff and flow rates were determined by monitoring 27 times in dry season and 4 times in rainy season. The concentrations of the dissolved refractory organic matter, R-DOC was the lowest in fall and similar in the other dry seasons. The particulate refractory organic matter, R-POC showed less fluctuation than R-DOC. In summer, mass loading was the highest than other dry seasons. The concentrations of R-DOC, R-POC were showed to be affected by runoff volume. The mass loading grows higher as runoff volume gets higher.