• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.2
• /
• pp.979-984
• /
• 2011

Although sludge production has been increased due to the number of the wastewater treatment plants expanded, needs of the techniques for the sludge reduction and disposal has been issued importantly because the sludge dumping to ocean is prohibited from 2012 by the London Dumping Convention. Therefore, the sludge solubilization using electrolysis as an alternative techniques for the sludge disposal was carried out in this study. Iridium coated titanium based insoluble electrodes were used and 20 volt was applied to the electrolysis reactor using DC power supply. Supernatants of the treated sludge was monitored: The soluble COD, TN, TP of it was increased to 151%, 22% and 6% respectively. And the sludge floc size distribution was changed, that is, the flocs ranged from 0.1 to 1.0 ${\mu}m$ were increased. All of these results indicate that the cells were lysed and the internal matters bursted out of the cell after electrolysis. As well as the reduction of the sludge production, the soluble organic matters from the cells could be used as an external carbon sources in the advanced wastewater treatment plants.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.11
• /
• pp.1141-1147
• /
• 2006

In order to applicate a newly method for powdered activated carbon(PAC) selection based on economic efficiency, PAC adsorption tests were performed for removal of MIB and dissolved organic carbon(DOC) in drinking water supplies. The removal rate of MIB increased when the PAC dose increased. The Coal-based PACs were superior for adsorption of MIB compared to wood-based PACs. PAC adsorption of DOC and $UV_{254}$ were a little different for different PACs and types of raw water, but both were lower than adsorption of MIB. Among the tested PACs, the one called P-1000 was most effective for removal of MIB, DOC and $UV_{254}$. Most of the organics in the tested samples were proven by excitation emission matrix(EEM) results to be fulvic-like materials. Especially, fulvic-like materials, humic-like materials, and soluble microbial byproduct(SMP)-like materials decreased after contact with PAC. P-1000 which had the lowest MIB cost index(MCI) was selected as the optimum PAC for the target water. PAC efficiency and treatability, particle size and distribution, and the cost associated with PAC dosing for MIB removal according to DOC concentration should all be considered before making the final selection of the best PAC for the target water.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.23 no.3
• /
• pp.117-126
• /
• 1987

The author has analysed profile of flow in rear of motion with single ball with low Reynolds number performed interface layers. For each system whose viscosity of the lower phase is as large as or large that of the upper phase, the profile has based on the thickness of the ball in the lower phase is nearly independent of both the ball single and the physical properties of the upper phase of the solution. The examine of the characteristics between Darwin's total displacement of the fluid and data obtained in this study, the averaged volume of each cases was corrected by the viscosity in the lower phase. When the viscosity in the lower phase is less than that of the upper phase, the volume based on the displacement of the fluid in rear region of ball are influenced by both ball size and the viscosity ratio of the upper phase to the lower phase. In the range of the Reynolds number less than a constant values, the volume ratio is influenced by both Reynolds number and Moltion number but mainly Reynolds. In range of Reynolds number over than the value, the volume ratio is independent of Reynolds number, but influenced by Moltion number.

• Resources Recycling
• /
• v.21 no.2
• /
• pp.34-40
• /
• 2012

$Pt_{10}$/C, $Pt_9Mn_1$/C, $Pt_7Mn_3$/C electrocatalysts for Polymer Electrolyte Membrane Fuel Cells(PEMFCs) were synthesized by reduction with HCHO and their activity as a oxygen reduction reaction(ORR) was examined at half cell. The electrochemical oxygen reduction reaction(ORR) was studied by using a glaasy carbon electrode through cyclic voltammetric curves(CV) in a 1 M $H_2SO_4$ solution. The ORR activities of $Pt_9Mn_1$/C were higher than $Pt_{10}$/C, $Pt_7Mn_3$/C. Also potential-current curves of $Pt_9Mn_1$/C at 0.9, 0.8, 0.7, 0.6V for 5minutes respectively were higher than $Pt_{10}$/C, $Pt_7Mn_3$/C. Physical characterization was made by using x-ray diffraction(XRD) and transmission electron microscope(TEM). The TEM images of $Pt_9Mn_1$/C, $Pt_{10}$/C catalysts showed homogenous particle distribution with particle size of about 2.7 nm, 3 nm respectively and then the XRD results showed that the crystalline structure of the synthesized catalysts are seen FCC structure.

• Korean Journal of Remote Sensing
• /
• v.26 no.4
• /
• pp.421-437
• /
• 2010

Surface particulate organic carbon (POC) concentration estimated from Maximum Normalized Difference Carbon Index (MNDCI) algorithm using SeaWiFS data is used to determine spatial and temporal variations of the Changjiang Diluted Water (CDW) in the East China Sea. 10-year monthly POC concentrations (1997-2007) show clearly seasonal variations. Inter-annual variation of POC in whole and three different areas separated by standard deviation is not linearly correlated with the Changjiang River discharge that has decreased after 1998. To determine more detailed spatial and temporal POC variations, we used empirical orthogonal function (EOF) analysis in summer (Jun.-Sep.) from 2000 to 2007. First mode is spatially and temporally correlated with the area influenced by the Changjiang River discharge. Second mode is temporally less sensitive with the Changjiang River discharge but spatially correlated with north-south patterns. Relatively higher POC variations during 2000 and 2003 were shown in the southern East China Sea. These patterns during 2004 and 2007 moved to the northern East China Sea. This phenomenon is better related to spatial variations of wind-direction than the amount of Changjiang River discharge, which is verified from in-situ measurement.

• Applied Chemistry for Engineering
• /
• v.32 no.6
• /
• pp.690-694
• /
• 2021

Carbon spheres (CS) were fabricated using glucose as a precursor in the hydrothermal method. Hollow TiO₂ (H-TiO₂) spheres with 200 nm, 500 nm, and 1,200 nm were synthesized by CS/TiO₂ core-shell particles via a sol-gel and calcination method. H-TiO₂ spheres with nano and micron sizes were characterized using FE-SEM, HR-TEM, and X-ray diffraction. The CIE color coordinate, solar reflectance, and heat shield temperatures of H-TiO₂/polyacrylate (PA) composite film were investigated using a UV-Vis-NIR spectrometer and homemade heat insulation temperature measuring device. H-TiO₂/PA composites exhibit excellent thermal insulation since the hollow structure filled with dry air has low thermal conductivity and near infrared light reflecting performance. The thermal insulation increased with increasing the hollow sphere (HS) size on H-TiO₂/PA composites. The PA composite film mixed with H-TiO₂ filled with 1200 nm HS reduced the heat shield temperature by 26 ℃ compared to that of the transparent glass counterpart.

• Applied Chemistry for Engineering
• /
• v.32 no.4
• /
• pp.461-466
• /
• 2021

In this article, a portable and cost-effective voltammetric biosensor with nanoparticles was developed for the measurements of heterogeneous nuclear ribonucleoprotein A1 protein (hnRNP A1) biomarker which can potentially be used for lung cancer diagnosis. Gold nanoparticles were first electrodeposited onto screen printed carbon electrode (SPCE) followed by immobilizing a single stranded DNA aptamer specific to hnRNP A1 onto the electrode surface. Ethanolamine was also used when immobilizing DNA aptamer on the surface to prevent signals from non-specific adsorption events. Sequential injection of hnRNP A1 biomarker and anti-hnRNP A1 conjugated with alkaline phosphatase (ALP) onto the aptamer chip surface allows to form the sandwich complex of DNA aptamer/hnRNP A1/ALP-anti-hnRNP A1 on the electrode surface which further reacted with 4-aminophenyl phosphate (APP). The electrocatalytic reaction of the enzyme, ALP, and the substrate, APP, resulting in the oxidative current response changes at -0.05 and -0.17 V (vs. Ag/AgCl) against the hnRNP A1 concentration was measured using cyclic and differential pulse voltammetry, respectively. The Au nanoparticles-integrated voltammetric biosensor was applied to analyze human normal serum solutions possibly suggesting potential applicability for lung cancer diagnosis.

• Journal of Life Science
• /
• v.34 no.1
• /
• pp.68-77
• /
• 2024

Airborne particulate matter (PM) is an environmentally hazardous pollutant that originates from various sources. PM is comprised of solid particles and liquid droplets of diverse composition and size. Hazardous chemical compositions of PM include elemental and organic carbon, organic compounds, biological compounds and metals. Upon acute and chronic PM exposure, toxic contaminants enter and accumulate within physiological systems and prompt cell structure changes accompanied with intracellular endoplasmic reticulum stress, mitochondrial dysfunction, oxidative stress, inflammation, lipid accumulation, and cell cycle arrest. Ultimately, these cellular response leads to the development of key characteristics of aging. In addition, PM internalization enhances autophagy reflux and lysosomal dysfunction, which is involved in cell aging. Previous studies have emphasized a positive association between PM and increased mortality or decreased lifespan, although these are evidenced mostly by observational studies. Direct evidence of the link between PM and aging is still limited. This review evaluates the evidence from not only observational studies but also in vitro and in vivo evidence of PM on aging progression and age-related diseases development. This evidence is based on age-associated cellular changes including endoplasmic reticulum stress, mitochondrial dysfunction, oxidative stress, inflammation, adipose accumulation, autophagy, which strengthen the association between PM exposure and aging. Understanding the underlying cellular responses under PM may allow for the development of new therapeutic targets for PM-induced aging.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.29 no.1
• /
• pp.1-13
• /
• 2024

The southwestern part of the East Sea is known to have a high primary productivity compared to those in the northern and eastern parts, which is attributed to nutrients supplies either by Tsushima Warm Current or by coastal upwelling. However, research on the biological pump in this area is limited. We developed machine learning models to estimate net community production (NCP), a measure of biological pump, with high spatial and time scales of 4 km and 8 days, respectively. The models were fed with the input parameters of sea surface temperature, chlorophyll-a, mixed layer depths, and photosynthetically active radiation and trained with observed NCP derived from high resolution measurements of surface O₂/Ar. The root mean square error between the predicted values by the best performing machine model and the observed NCP was 6 mmol O₂ m^-2 d^-1, corresponding to 15% of the average of observed NCP. The NCP in the central part of the Ulleung Basin was highest in March at 49 mmol O₂ m^-2 d^-1 and lowest in June and July at 18 mmol O₂ m^-2 d^-1. These seasonal variations were similar to the vertical nitrate flux based on the ³He gas exchange rate and to the particulate organic carbon flux estimated by the ²³⁴Th disequilibrium method. To expand this method, which produces NCP estimate for spring and summer, to autumn and winter, it is necessary to devise a way to correct bias in NCP by the entrainment of subsurface waters during the seasons.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.24 no.4
• /
• pp.519-534
• /
• 2019

When the fresh water from the artificial lakes (Ganwolho and Bunamho) were discharged to Cheonsu Bay in summer to prevent the flood over the reclaimed farmland near the lakes, the impact on water qualities (nutrients, organic matters, trace metals) within the bay was investigated through four surveys (June, July, August and October, 2011). Dissolved inorganic nitrogen (DIN) increased about as much as 3-4 times over the whole water column when the freshwater was discharged. And the main species composition of DIN changed from ammonia to nitrate. Dissolved inorganic phosphorus (DIP) decreased as much as 2 times in surface waters, but increased as much as 1.5 times in deep waters, and also silicate concentrations increased as much as 3-4 times in deep waters of the inner bay. The N/P ratios in Chunsu bay seawaters were much higher (2 to 7 times) than the Redfield ratio when the freshwaters were discharged, which indicated the phosphorus limiting in the phytoplankton growth. Dissolved organic carbon (DOC) and nitrogen (DON) increased as much as about 2 times. In addition, particulate organic matters (POC, PON, POP, Bio-Si) increased as much as above 2 times in the surface waters of the inner bay. Trace metals (Fe, Mn, Co, Ni, Cu) increased in the surface waters of the inner bay, but dissolved Cd concentrations decreased as much as 2 times. Therefore, when the contaminated fresh waters from the artificial lakes were discharged into the bay, nutrients, organic matters and trace metals generally increased compared to normal period. Since the phytoplankton bloom occurred in the surface waters of the inner bay, dissolved oxygens at the surface waters were oversaturated and hence hypoxic in the deep waters. Highly enriched nutrients concentrations were found in deep waters of the inner bay, which was accompanied with the hypoxic condition. Finally, the water quality in the inner bay of the Chunsu bay was deteriorated from less than grade 3 in normal periods to grade 5 when the freshwaters from the artificial lakes were discharged in summer.