• Journal of Korean Society on Water Environment
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• v.30 no.5
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• pp.559-567
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• 2014

Since the ocean dumping of organic wastes is prohibited under the London Convention, the need for land treatment of food waste leachate (FWL) has significantly been growing in recent years. This study was conducted to use thermal solubilization to turn FWL into a form that can easily be degraded during the anaerobic digestion process, thereby reducing the percentage of solids and increasing the production of methane. To derive the optimal operating conditions of thermal solubilization, a laboratory-scale reactor was built and operated. The optimal reaction temperature and time turned out to be $190^{\circ}C$ and 90 min, respectively. The BMP test showed a methane production of 465 mL $CH_4/g$ $COD_{Cr}$ and a biodegradation rate of 90.1%. The production of methane rose by about 15%, compared with no the application of thermal solubilization. To reduce the solid content of FWL and improve the methane production, therefore, it may be helpful to apply thermal solubilization to pre-treatment facilities for anaerobic digestion.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.1
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• pp.49-58
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• 2013

A selected halogenated organic contaminant, monochlorophenol was successfully degraded by photocatalytic reaction in a circulating batch system. The photocatalytic degradation in most cases follows first-order kinetics. The photocatalytic reaction rate increased in the $TiO_2$ dosage range of 0.1 g/L to 0.4 g/L, then decreased with further increase of the dosage. Also the degradation rate increased over the range of the retention time from 0.49 min. to 0.94 min., then decreased with further increase of the retention time in the circulating batch reactor. The photocatalytic activity was enhanced by addition of metal impurities, platinum(Pt) and palladium(Pd) onto the photocatalysts. The photocatalytic degradation rate increased with the increase of Pt and Pd in the content range of 0 to 2wt %, then decreased with further increase of the metal contents. Therefore the metal loading to $TiO_2$ influence the degradation rate of a halogenated organic compound by acting as electron traps, consequently reducing the electron/positive hole pair recombination rate.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.449-455
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• 2009

The antioxidant properties of water extracted polysaccharides (PW), 1%(w/v) NaOH extracted polysaccharides (PN1), and 5%(w/v) NaOH extracted polysaccharides (PN5) were assessed in this paper. PW showed good capability of scavenging $H_2O_2$, anti-lipid peroxidation, reduction power, and scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH). The maximum values were all observed at the dose of 1 mg/mL sample. As far as the antioxidant activities of PN1 were concerned, the capability of scavenging superoxide radical, chelating metal, and total antioxidation showed higher than those of PN5. When polysaccharide concentration was 1 mg/mL, the 3 index described above were attached 71.8%, 51.6%, and $446.3{\mu}M$ Trolox equivalent, respectively. With respect to PN5, higher capabilities of scavenging hydroxyl free radicals were obtained while the peak of 84.8% was observed at the concentration of 1.0 mg/mL. Moreover, the concentration-dependent influences were characterized in all cases.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2865-2870
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• 2013

Ni-Ag core-shell nanoparticles were synthesized by polyol process and microemulsion technique successfully. In the polyol process, a chemical reduction method for preparing highly dispersed pure nickel and Ag shell formation have been reported. The approach involved the control of reaction temperature and reaction time in presence of organic solvent (ethylene glycol) as a reducing agent for Ag cation with poly(vinyl-pyrrolidone) (PVP. Mw = 40000) as a capping agent. In microemulsion method, the emulsion was prepared by water/cetyltrimetylammonium bromide (CTAB)/cyclohexane. The size of microemulsion droplet was determined by the molar ratio of water to surfactant (${\omega}_o$). The core-shell formation along with the change in structural phase and stability against oxidation at high temperature heat treatments of nanoparticles were investigated by X-ray diffraction and TEM analysis. Under optimum conditions the polyol process gives the Ni-Ag core-shell structures with 13 nm Ni core covered with 3 nm Ag shell, while the microemulsion method gives Ni core diameter of 8 nm with Ag shell of thickness 6 nm. The synthesized Ni-Ag core-shell nanoparticles were stable against oxidation up to $300^{\circ}C$.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.5
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• pp.485-493
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• 2010

Chemical coagulation destabilizes colloidal particles so that particles grow to larger flocs. Solid particles are then removed by solid-liquid separation after typical precipitation. Rapid precipitation enhances the separation by reducing the precipitation time with larger and denser particles. Conventionally, polyelectolyte compounds (polymers) function as a flocculant aid by introducing a interparticle binding, which increases the particle size and density. And more recent ballasted flocculation adds a ballasting agent (microsand) to form denser particles with its high-density(sp gr=2.65). The current research was to evaluate the manner in which ballasted flocs are formed under different injection timings of microsand and to recognize the effects on floc formation. $FeCl_3$ as a coagulant, anionic polymer for a flocculation aid and microsand were used for the floc formation. Floc size (diameter) was widely ranged with the highest mean value when microsand was injected between $FeCl_3$ and polymer. Mean floc density was larger when the floc formed smaller. Settling velocity increased with larger floc size, whilst not significantly affected by the timing of microsand injection. The additional slow mixing on floc formation increased floc size to some extent.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.12
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• pp.1025-1032
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• 2006

This is to characterize the fluid mechanics of surfactant water solutions, which exhibit drag reduction in the turbulent flow as compared to pure water. The emphasis is placed on those fluid characteristic aspects of drag reducing solutions which are relevant for application in closed circulation loops for the purpose of pumping power savings, like hydronic cooling and heating systems in buildings. The experiments are carried out with the solutions of the surfactant Beraid DR-IW 616 in concentration of $100{\sim}3,000ppm$. The following key parameters are focused in this study: surfactant concentration, solution temperature and pipe diameter.

• Journal of the East Asian Society of Dietary Life
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• v.14 no.6
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• pp.571-575
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• 2004

This study was conducted to investigate the effects of Glycyrrhizia uralensis water extract on the quality of Cheonggukjang(fermented soybean paste). Soybeans were soaked for 24 hrs, steamed for 1 hr at 121, mixed with G. uralensis extract(0, 1, 3 and 5%) and fermented for 54 hrs at 40 after inoculation of Bacillus lichenifomis. The amounts of viscous substance and reducing sugar, and pH of the products were increased when the G. uralensis extract was added. The color of the products was changed to dark yellow by the addition of G. uralensis extract. Ammonia odor and bitter taste decreased as the G. uralensis extract content increased. The products added with 5% of G. uralensis extract showed higher acceptability scores than the others. Results suggest that the water extract of G. uralensis could be used as an additive to improve the quality of Cheonggukjang.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.301-313
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• 2017

This paper presents the fibre-matrix interfacial properties of hooked end steel fibres embedded in ultra-high performance mortars with various water/binder (W/B) ratios. The principle objective was to improve bond behaviour in terms of bond strength by reducing the (W/B) ratio to a minimum. Results show that a decrease in W/B ratio has a significant effect on the bond-slip behaviour of both types of 3D fibres, especially when the W/B ratio was reduced from 0.25 to 0.15. Furthermore, the optimization in maximizing pullout load and total pullout work is found to be more prominent for the 3D fibres with a larger diameter than for fibres with a smaller diameter. On the contrary, increasing the embedded length of the 3D fibres did not result in an improvement on the maximum pullout load, but increase in the total pullout work.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.342-344
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• 2018

This paper shows the possibility to substitute statistical methods such as mean imputation, correlation coefficient analysis, graph correlation analysis for the proposed algorithm, and replace statistician for processing various abnormal data measured in the water treatment process with it. In addition, this study aims to model a data-filtering system based on a recent fractile pattern and a deep learning-based LSTM algorithm in order to improve the reliability and validation of the algorithm, using the open-sourced libraries such as KERAS, THEANO, TENSORFLOW, etc.

• Resources Recycling
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• v.16 no.5
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• pp.3-7
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• 2007

Waste aluminum dross was processed to prepare alum with sulfuric acid, and poly aluminum chloride(PAC) with hydrochloric acid. Metallic aluminum remained in the waste dross was dissolved into the sulfuric acid solution, and the solution could be used as alum for water treatment chemicals after adjusting the required alumina concentration and pH of the solution. Also, it was dissolved into the hydrochloric acid solution and processed to make PAC solution. Compared with the conventional method for preparation of alum and PAC using aluminum hydroxide, material cost could be saved in this method. Also, there is an additional merit in view of recycling of the waste aluminum dross by reducing the amount of waste disposed to landfill.