• Journal of Advanced Marine Engineering and Technology
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• v.23 no.1
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• pp.25-32
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• 1999

This study was carried out to reduce NOx emissions from diesel engine and to investigate the variation of engine performance using the water injection. In this study the water was extracted from the exhaust gas and injected directly into the intake port with the inlet charge. The water condensing system operated as a closed system without any supplementary water supply. The experimental parameters such as the revolution the torque and the water injection rate are varied and the result from this experiment found the significant NOx reduction whereas the smoke emission increases as water/air ratio increases as the cases like the EGR. In spite of increasing the quantity of the water injection the engine output was slightly decreased and the specific fuel consumption was increased as was anticipated. Especially the system was founded to be effective on the reduction of the NOx emissions at the high load region relatively.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.225-230
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• 2001

Cast-in-place foamed concrete is a high porous material placed as base the layer of mortar screeds in the panel heating system, so the quality of mortar is affected by it. Therefore, this study is aims to investigate how the absorption characteristics of foamed concrete influences on mortar screeds according to the foamed ratio-62%, 67% and 72%- and the surface treatments of foamed concrete-water and acrylic emulsion primer spray, etc. The result of this study shows that water-spray in the surface of foamed concrete has a good effects to reduce mortar cracking.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.9
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• pp.1247-1254
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• 2000

The effects of recirculated exhaust gas on the characteristics of $NO_x$ and soot emissions under a wide range of engine load have been experimentally investigated by a water-cooled, four-cylinder, indirect injection, four cycle and marine diesel engine operating at two kinds of engine speeds. The simultaneous control of $NO_x$ and soot emissions in diesel engines is targeted in this study. The EGR system is used to reduce $NO_x$ emissions, and a novel diesel soot removal device with a cylinder-type scrubber for the experiment system which has 6 water injectors(A water injector has 144 nozzles in 1.0 mm diameter) is specially designed and manufactured to reduce the soot contents in the recirculated exhaust gas to intake system of the engines. The intake oxygen concentration and the mean equivalence ratio calculated by the intake air flow and fuel consumption rate, and the exhaust oxygen concentration measured are used to analyse and discuss the influences of EGR rate on $NO_x$ and soot emissions. The experiments are performed at the fixed fuel injection timing of $15.3^{\circ}$ BTDC regardless of experimental conditions. It is found that $NO_x$ emissions are decreased and soot emissions are increased owing to the drop of intake oxygen concentration and exhaust oxygen concentration, and the rise of equivalence ratio as the EGR rate rises.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1279-1284
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• 2008

The alternative energy has lately attracted considerable attention due to the high oil price and environment problem. Deep sea water that is one of the natural energy sources should be getting popular continually to reduce the environment problem. In this study, cooling system of deep sea water using heat exchangers of two hotels where is located in near Hae-undae Bay has been analyzed on the quantity of electricity comparison between existing cooling system and deep seawater cooling system. As shortly, the results of study showed that the first building approximately saves 370 millions won per year, also the second building saves 248 millions won per year. It means that the cooling system by using deep sea water has great worth to reduce the ratio of fossil fuel.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.2
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• pp.196-206
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• 2000

Methanogenesis and denitrification in an upflow sludge baffled filter (UBF) reactor were studied using glucose as a fermentative substrate. Experiments were carried out to investigate how to reduce ammonification by changing alkalinity and $COD/NO_3-N$ ratio. Characteristics of granular sludges were examined by specifics methanogenic activity(SMA) and specific denitrification rate(SDR) tests. Microstructures of granules were examined using a scanning electron microscopy(SEM). It was found that COD was removed efficiently owing to the diverse microorganisms. In nitrate conversion, not only $COD/NO_3-N$ ratio but also influent alkalinity played important role in the ratio of denitrification and ammonification of nitrate. This reactor achieved over 95% COD and 99% nitrate removal efficiencies when influent contained 4000 mgCOD/L and $700mgNO_3-N/L$ at the hydraulic retention time of 24 hours. As $COD/NO_3-N$ ratio decreased, granular methanogenic activities using acetate and butyrate as substrates increased while activities using propionate and glucose decreased. There were three types in granules according to the surface color; gray, yellowish gray, and black. Gray or yellowish gray-colored granules were composed two layers, which were composed of black inner side and gray or yellowish gray surface substances. SEM illustrated that both were rod-type and cocci-type microorganisms resembling Methanothrix sp. and Methanococci sp. This study showed that by controlling the influent alkalinity and $COD/NO_3-N$ ratio, ammonification and denitrification could be manipulated.

• Korean journal of food and cookery science
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• v.8 no.3
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• pp.333-341
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• 1992

The physicochemical, rheological and sensory characteristics of 'BACKSULGIES', which was added with potato peel, guar gum or polydextrose, were investigated. The maximum acceptable addition ratio of dietary fiber to 'BACKSULGI' was 10%. And optimal addition ratio was 3% for all samples. The water binding capacity was affected by dietary fiber sources and incubation conditions (temperature and time). The Guar gum had me highest value of water binding capacity. The solubility was highly related with water binding capacity and me swelling power was increased with temperature increment. The degree of gelatinization was not significantly different with dietary fiber sources. But me values of gelatinization of 'BACKSULGIES' added with dietary fibers were significantly higher than mose of 'BACKSULGI' with no dietary fiber. Generally hardness and brittleness incresed along with storage time. But me hardness of 'BACKSULGIES' added with dietary fibers was significantly lower man those of 'BACKSULGI' with no dietary fiber. The retardation effect of dietary fibers for retrogradation of 'BACKSULGIES' was also proved by time constant determination of Avrami equation. Sernsory evaluation revealed that me addition of dietary fibers did not reduce the organoreptic quality. Therefore potato peel 3%, guar gum 3%, polydextrose 3% were optimum addition ratio which could be accepted as conventional 'BACKSULGI'. As me results of this study, it was proved mat the additions of dietary fibers to 'BACKSULGI' had the retardation effect of retrogradation.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.2
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• pp.51-57
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• 2009

The purpose of this study was to investigate characteristics of behavior of nutrients such as TN (Total nitrogen), TDN (Total dissolved nitrogen), TP (Total phosphorus) TDP (Total dissolved phosphorous) in runoff water from a nonpoint source dominated watershed ($6.67\;km^2$). Regular and intensive flow measurement and water sampling were taken during two years (February 2002 to January 2004) in the Ingyeong River, a tributary of the Han River. The mean concentrations of nutrients during rainy days were significantly (p < 0.05) higher than those during dry days. The mean TDN/TN ratio in rainy days (95%) is almost identical to that in dry days (96%), but mean TDP/TP ratio in rainy days (24%) significantly decreased compared with that in dry days (66%), suggesting that dominant form of TP is shifted from dissolved form to particulate form. Accordingly, the measures (.eg. filter strips, cover crops) to reduce soil erosion for fallow upland in the rainy season should be taken to control particulate phosphorous.

• Computers and Concrete
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• v.11 no.4
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• pp.305-316
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• 2013

This paper aims to study the effect of measurement methods and cracking on chloride transport of concrete materials. Three kinds of measurement methods were carried out, including immersion test, rapid migration test and steady-state migration test. All of these measurements of chloride transport show that chloride ion diffusion coefficient decreased with the reduction of water to cement ratio. Results of the immersion test were less than that of rapid migration test and steady-state migration test. For the specimen of lower water to cement ratio, the external electrical field has little effect on chloride binding relatively. Compared with the results obtained by these different measurement methods, the lower water to cement ratio may cause smaller differences among these different methods. The external voltage can reduce chloride binding of concrete, and the higher electrical field made a strong impact on the chloride binding. Considering the effect of high voltage on the specimen, results indicate that results based on the steady-state migration test should be more reasonable. For cracked concrete, cracking can accelerate the chloride ion diffusion.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.3275-3284
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• 2012

This study analyzed a 3D hydrodynamic advection diffusion using the EFDC model (Environmental Fluid Dynamics Code) in the agriculture lake to prevent stratification when we install a water circulator. EFDC model was predicted the range of the water circulator and various operational parameters ware derived for minimize the impact of the internal lake. Through EFDC simulation, water circulation is started overall circulation after 30days and a lake overall circulation showed that it was possible operated the water circulator after about 100days. Also, advection diffusion concentration was low in a lake when water circulator operate intermittent condition than continuous condition. And the entire circulation was stable in this condition. The S/B (Surface/Bottom) ratio can reduce the impact of lake as the surface water mixing a lot of. When the same condition (S/B ratio(3:1)), Case 8 (50days operation: 50days stop) of condition were able to minimize the impact of lake.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.3
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• pp.65-71
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• 2010

This study was conducted to investigate the dynamics of nutrients such as total nitrogen (TN), nitrate nitrogen ($NO_3$-N) total phosphorous (TP), and phosphate phosphorous ($PO_4$-P) in outflow from a cabbage farmland in a mixed land-use watershed. The TN concentrations in groundwater showed twice peaks in late July 2006 and late March 2007 (3.8, 4.7 mg/L, respectively), when it rained shortly after fertilizer application, indicating that nitrogen leaching is greatly influenced by fertilization and rainfall. The mean concentrations of TN and $NO_3$-N in surface water were not significantly higher than those in groundwater, while the mean concentrations of TP and $PO_4$-P in surface water were significantly (p < 0.05) were higher than those in groundwater. The TN concentrations in groundwater were generally higher than those in surface water during fertilization and early growing season due to the effect of fertilization, but vice versa in the other periods. In contrast, the TP concentrations in groundwater were always lower than those in surface water due to the sorption of particulate phosphorous by soil. The ratio of TN load in baseflow to that in total TN load (39 %) was much greater than the TP ratio (7 %), suggesting that baseflow contribute to nitrogen export. Therefore, proper fertilization management should be taken to reduce nitrogen load through baseflow.