• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.419-427
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• 2018

The purpose of this study is to recycle steel slag generated from the iron producing process and to use steel slag as a construction material which is currently landfilled Steel slag is subjected to aging treatment due to the problem of expansion and collapse when it reacts with water. The Slag Atomizing Technology (SAT) method developed to solve these problems of expanding collapse of steel slag. In this study, experimental study on the emergency repair mortar using the reducing slag, electric arc furnace slag and silicon manganese slag manufactured by the SAT method is Reduced slag was shown an accelerated hydration when it was replaced with rapidly-setting cement, and the rate of substitution was equivalent to 15%. It is shown that the electric furnace oxide slag is equivalent to 100% of the natural aggregate, and it can be replaced by 15-30% when the silicon manganic slag is substituted for the electric furnace oxide slag. With the above formulation, it was possible to design the rapidly repair mortar for road use. These recycling slags can contribute on achieving sustainability of construction industry by reducing the use of cement and natural aggregates and by reducing the generation of carbon dioxide and recycling waste slag.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.500-505
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• 2007

The objectives of this research were to (1) identify the membrane fouling potential due to different fractions of NOM (2) correlate the physicochemical properties of NOM and membranes with the adsorption of humic substances on membrane (4) find out the effect of membrane physical and chemical washing according to membrane material. The static adsorption test and adsorption test showed that hydrophobic organics adsorbed much more quickly than hydrophilic organics. In case of the effect of membrane properties on the adsorption of organic fractions, the adsorption rate ratio(a) of hydrophobic membrane (0.016, 0.077) was greater than that of hydrophilic membrane (0.010, 0.033) regardless of the kind of organic fractions. This suggests that the UF membrane fouling were occurred mainly by internal pore size decreasing due to adsorption of organic into pore surface for hydrophobic membrane, and by sieving of organics and forming a gel layer on the membrane surface for hydrophilic membrane. In conclusion, the decrease in the pore volume, which was caused by the organic adsorption into the internal pore, was greater with the hydrophobic membrane than with the hydrophilic membrane. In case of the effect of membrane properties on permeate flux, the rate of flux decline for the hydrophobic membrane was significantly greater than that for the hydrophilic membrane.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.523-528
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• 2007

The objectives of this research are to investigate the mechanism of coagulation affecting UF, find out the effect of metal salt coagulant on membrane fouling. Either rapid mixing + UF or slow mixing + UF process caused much less flux decline. For PACl coagulant, the rate of flux decline was reduced for both hydrophilic and hydrophobic membrane than alum due to higher formation of flocs. In addition, the rate of flux decline for the hydrophobic membrane was significantly greater than for the hydrophilic membrane, regardless of pretreatment conditions. In general, Coagulation pretreatment significantly reduced the fouling of the hydrophilic membrane, but did little decrease the flux reduction of the hydrophobic membrane. When an Al(III) salt is added to water, monomers, polymers, or solid precipitates may form. Different Al(III) coagulants (alum and PACl) show to have different Al species distribution over a rapid mixing condition. During the rapid mixing period, for alum, formation of dissolved Al(III) (monomer and polymer) increases, but for PACl, precipitates of $Al(OH)_{3(s)}$ increases rapidly. This experimental results pointed out that precipitates of $Al(OH)_{3(s)}$ rather than dissolved Al(III) formation is major factor affecting flux decline for the membrane.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.230-236
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• 2020

A trash screen is installed in front of the inflow channel of a drainage pumping station, sewage treatment plant, and a power plant to block floating contaminants. The bottleneck phenomenon, which decreases the water inflow, causes damage to the damper as a result of clogging in between the screen if string type obstacles are not removed. In this paper, the apron was removed, and the screen was expanded, to prevent breakage of the bottleneck phenomenon and string type obstacles. This was designed using an extended rake by adding an inner rake in between the screen interspace to remove the bottleneck phenomenon and string type obstacles. To design the inner rake that satisfies the allowable stresses of the existing damper rake, the experiment points were determined according to the experimental design method using the inner rake vertical length and the thickness of the reinforced section as parameters. The use of the ANSYS static structural module and statistical analysis tool R software gives the optimized shape according to the response surface method. The relative error between the response surface analysis results and the simulation results was 1.63% of the determined optimal design-point rake length of 210.2 mm and the reinforcement section thickness of 2 mm. Through empirical experiments, a test rake was constructed to the actual size, and approximately 97% of the bottleneck phenomenon and string type obstacles could be removed.

• Journal of Surface Science and Engineering
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• v.51 no.2
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• pp.95-103
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• 2018

Recently, many types of constructional steels have been often exposed to under severe corrosive environments due to acid rain with increasing environmental contamination. In order to inhibit their corrosion in severe corrosive environments, a painting method has been widely applied to numerous constructional steels of land as well as marine. Therefore, development of paint having a good quality of corrosion resistance is considered to be very important. In this study, four types of anti-corrosive paints (AP: Phenol epoxy, AC: Ceramic epoxy, AT: Coal tar epoxy, AH: High solid epoxy) were coated to the specimens, and then, were immerged in various salt solutions (0.1, 0.3, 3, 6, 9 and 15% NaCl solutions) for 11 days. And, the corrosion resistance of these samples by effect of osmotic pressure with salt concentration was investigated with electrochemical methods such as measurement of corrosion potential, impedance and corrosion current density. The corrosion current densities of all samples (AC, AT and AH) submerged in 3% NaCl solution exhibited the smallest values compared to other salt solutions. However, in the case of lower values of salt solutions than 3% NaCl solution, the corrosion current density increased again because it makes easier for water, dissolved oxygen and chloride ion etc. to invade toward inner side of coating film due to increasing of the osmotic pressure than 3% NaCl solution, but in the case of higher values of salt solutions than 3% NaCl solution, the coating film is easily deteriorated due to high concentration of chloride ion rather than the osmotic pressure, which resulted in increasing the corrosion current density. In particular, the AC sample indicated the best corrosion resistance in 6% NaCl solution compared to other samples. Consequently, it is considered that the corrosion mechanism of the coated steel plate is completely different from bare steel plate, and the corrosion resistance of coating film by osmotic pressure and chloride ion depend on various types of epoxy of paint in NaCl solution.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.72-82
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• 1986

There were three important species among the marine organisms which were cultured in the inter tidal zone in the old days, and an ark-shell was one of them. Exaiming old books and reports concerning fishery were made in order to reveal the history and industrial trend of ark-shell culture. Ark-shell was called by the different names in the old days "Komak" and "Sohap". The name of Komak was originated in the southern coast area in the 1,700s, and from the begining of 18 century Komak was used only. Ark-shell was produced in all southern and western coast areas, where a little of fresh water flows into the calm inner sea and the intertidal zone is well developed. It was well known that ark-shells shell as well as its flesh took the effect of a medicine. Its culturing method in Korea seems to be derived from China in the beginning of 19 century, it was cultured first at the southern area of Chollanam-do. It was considered as the side business, but after Korean war it is produced on the basis of cooperative work, now its production is quite increased (more than $5,000\fra{M}{T}$) due to the goverments development policy.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.648-653
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• 2010

This study was performed to investigate the inhibitory activity of Sargassum thunbergii (ST) against ${\alpha}$-amylase and elucidate the availability of ST extract as a functional food agent. To test the inhibitory activity of ST against ${\alpha}$-amylase, porcine pancreatic ${\alpha}$-amylase and potato starch were used as substrates. It was revealed that ST crude ethanol extracts have high ${\alpha}$-amylase inhibitory activity. Subsequently, ST crude ethanol extract was separated into five partition layers by solvent extraction: n-hexane, chloroform, ethyl acetate, butanol, and water. Chloroform and n-hexane fractions showed higher inhibitory activities than did acarbose (positive control). To confirm the changes in enzyme inhibitory activity by physical treatments, ST crude ethanol extract was subjected to heat, pH, and ${\gamma}$-irradiation treatments. In all heat treatments with the exception of one ($121^{\circ}C$, 15 min), the inhibitory activity was increased compared with the untreated group. With regard to pH stability, ST extract showed no significant changes at pH 4.6, but somewhat decreased inhibitory activity was revealed at pH 2, 8, and 10. On the other hand, ST ethanol extract was stable under ${\gamma}$-irradiation under all conditions (3.20 kGy). In summary, ST ethanol extract can be used in the food industry as a natural ${\alpha}$-amylase inhibitor.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.438-443
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• 2007

This study was done to investigate perchlorate contamination in Nakdong river. The perchlorate was detected in Nakdong river and ranged from ND to $82.1{\mu}g/L$. The highest concentration was observed in Wheguan. The perchlorate concentration was decreased with the down stream of Nakdong river. Three different virgin activated carbons made of each coal(Calgon), coconut(Samchully) and wood(Picabiol) based activated carbon(AC) were tested for an adsorption performance of perchlorate in a continuous adsorption column. Breakthrough behavior was investigated that the breakthrough points of coal, coconut and wood based AC as 2,300 bed volumn(BV), 719 BV and 288 BV respectively. Adsorption capacity(X/M) of real, coconut and wood based AC was observed. The experimental results of adsorption capacity showed that coal based AC was highest$(768.2{\mu}g/g)$, coconut based AC was intermediate$(299{\mu}g/g)$ and wood based AC was lowest$(99.2{\mu}g/g)$. Moreover, carbon usage rates(CURs) for coal, coconut and wood based AC had been shown as 0.71 g/day, 2.16 g/day and 3.45 g/day respectively. The constant characteristic of the system, k of coal, coconut and wood based ACs were found to be 307.2, 102.5 and 94.2, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.580-586
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• 2019

Fried-fish snacks containing surimi are a popular seafood product in Asia. To prepare fried-fish snacks, various ingredients are added to surimi. Among them, starch is important for producing snacks of desirable texture and taste. We investigated the physicochemical properties of fried-fish snacks containing arrowroot, potato, sweet potato, corn, and tapioca starches. The fried-fish snack with arrowroot starch showed the highest drying rate; after drying for 3 hours, the water content was unchanged. None of the starches affected the total volatile basic nitrogen values of the fried-fish snacks, which were approximately 1.5 mg/100 g, indicating freshness. The fried-fish snacks with corn and arrowroot starches had the highest brightness (L) values and the fried-fish snack with tapioca starch, the lowest L value. The hardness value of the fried-fish snack with tapioca starch was significantly higher than that of the other fried-fish snacks. In the sensory evaluation, the fried-fish snacks with arrowroot starch showed the best overall acceptance.

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.420-423
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• 2010

The proanthocyanidin fraction was isolated from the wild grape (Vitis amurensis) peel and its antioxidant capacities were examined to promote the utilization of wild grape by-products. The 70% acetone crude extract of the wild grape peel was fractionated with hexane, ethyl acetate, and water. The ethyl acetate fraction was applied to a Sephadex LH-20 column chromatograph, which was eluted with 50% methanol, 75% methanol, and 75% acetone. The proanthocyanidin characteristics and contents of the isolated fractions were investigated by the vanillin-$H_2SO_4$ and BuOH-HCl methods. Fraction 6 had the highest proanthocyanidin content ($49.35{\pm}2.75\;g%$) among the isolated fractions. The antioxidant activities of the proanthocyanidin fraction were examined by DPPH radical scavenging, FRAP assay, and total phenolic contents. The FRAP values and total phenolic contents of the fractions ranged from 3.54 to 32.25 mmol/kg and from 4.48 to 50.80 g/100 g, respectively. The proanthocyanidin contents was strongly correlated with DPPH radical scavenging activities, FRAP values, and total phenolic contents.