• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.393-407
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• 1997

A survey of biological and chemical characteristics in the middle-northern East Sea of Korea was carried out at 28 stations in October, 1995 on board R/V Tam-Yang. On the basis of the vertical profiles of temperature, salinity and dissolved oxygen, water masses in the study area were divided into 5 major groups; (1) Low Saline Surface Water (LSSW), (2) Tsushima Surface Water (TSW), (3) Tsushima Middle Water (TMW), (4) North Korean Cold Water (NKCW), (5) last Sea Porper Water (ESPW). Other 4 mixed water masses were also observed. It is highly possible that the LSSW which occured at depths of $0\~30m$ in the most southern part of the study area is originated from the Yangtze River (Kiang) of China due to very low salinity $(<32.0\%_{\circ})$ relatively high concentration of dissolved silicate and no sources of freshwater input into that area. Oxygen maximum layer in the vertical profile was located near surface at northern cold waters and became deeper at the warm southern area. Oxygen minimum layer af depths $50\~100m$, which is TMW, were found in only southern area. In the vortical profiles of nutrients, the concentrations were very low in the surface layer and increased drammatically near the thermocline. The highest concentration occurred in the ESPW. The relatively low value of Si/P ratio in the ESPW (13.63) compared to other reports in the East Sea was due to continuous increase of P with depth as well as Si. The N : P ratio was about 6.92, showing that nitrogenous nutrient is the limiting factor for phytoplankton growth. The exponential relationship between Si and P, compared to the linear relationship between N and P, indicates that nitrate and phosphate have approximately the same regenerative pattern, but silicate has delayed regenerative pattern.

• Economic and Environmental Geology
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• v.36 no.2
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• pp.111-121
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• 2003

The objective of this study is to investigate the physical and chemical properties for environmental assessment of water system affected by acid mine drainage (AMD) from coal mining activities in the Youngwol, Jungseon and Pyungchang areas in Korea. During November 2000 to July 2002, 6 times of water samples were collected season-ally from acid mine drainage and nearby streams at 13 coal mines in the study area. The physical and chemical properties including pH, Eh, TDS, salinity, bicarbonates and DO were measured in the field. Eighteen cations includ-ing Al, Ca, Fe, Mg, Mn and Zn, and 6 anions including nitrates and sulfates were also analyzed by ICP-AES and If, respectively. Acid water from the Jungam coal mine has typical characteristics of AMD with very low pH(3∼4) and high TDS(1,000∼5,000 mg/1). Relatively high concentrations(mg/kg) of heavy meals, especially for Al(380), Fe(80), Mn(44) and Zn(8), were found in water samples from the Jungam coal mine area. Water samples from the Seojin, Sebang and Sungjin coal mines also contained over 50 mg/l of Al, >100 mg/1 of Fe and )10 mg/1 of Mn. In addition to anioins, over 1,000 mg/l of sulfate was found in several water samples. Seasonally, the concentrations of metals and sulfates varied; wet season samples were relatively higher in metals and sulfates than dry season samples. It is needed to establish the proper remediation and environmental monitoring of the AMD continuously.

• Clean Technology
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• v.28 no.1
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• pp.63-78
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• 2022

Electronics industrial wastewater treatment facilities release organic wastewaters containing high concentrations of organic pollutants and more than 20 toxic non-biodegradable pollutants. One of the major challenges of the fourth industrial revolution era for the electronics industry is how to treat electronics industrial wastewater efficiently. Therefore, it is necessary to develop an electronics industrial wastewater modeling technique that can evaluate the removal efficiency of organic pollutants, such as chemical oxygen demand (COD), total nitrogen (TN), total phosphorous (TP), and tetramethylammonium hydroxide (TMAH), by digital twinning an electronics industrial organic wastewater treatment facility in a cyber physical system (CPS). In this study, an electronics industrial wastewater activated sludge model (e-ASM) was developed based on the theoretical reaction rates for the removal mechanisms of electronics industrial wastewater considering the growth and decay of micro-organisms. The developed e-ASM can model complex biological removal mechanisms, such as the inhibition of nitrification micro-organisms by non-biodegradable organic pollutants including TMAH, as well as the oxidation, nitrification, and denitrification processes. The proposed e-ASM can be implemented as a Water Digital Twin for real electronics industrial wastewater treatment systems and be utilized for process modeling, effluent quality prediction, process selection, and design efficiency across varying influent characteristics on a CPS.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.13-23
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• 2008

The triaxial compression tests and consolidation tests using NaCl solution and leachates as substitute pore (or saturated) water in samples were carried out to find out the behavior characteristics of strength, deformation and permeability coefficient of contaminated clay. Also, the chemical property analysis on the clay samples using scanning electron microscope and energy dispersive x-ray spectrometer were involved. The magnitudes of composition ratio were shown in the order of O, C, Si, Al, and Fe as a result of chemical composition analysis for clay samples. Besides, as the results of triaxial compression tests and consolidation tests, the shear strength, compression and permeability properties were increased with increasing in the concentration of contaminant (NaCl). It may be considered that these circumstances be caused by the changes of soil structure to flocculent structure due to the decrease in the thickness of diffuse double layer with increasing in the concentration of electrolyte. MT3D model was also using to grasp the procedures that the groundwater may be contaminated by the leachates permeated through the clay liner. The results of contaminant transport analysis showed a tendency that the predicted concentration of groundwater was higher with increasing in the initial concentration of $Cl^-$ ion and increased as a nonlinear curves with time. The transportation distance calculated by the use of regression equation between the distance from contaminant source and the concentration of $Cl^-$ ion was increased with increasing the initial concentration.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.718-725
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• 1999

In order to investigate the interaction characteristics of poly(dimethylsiloxane) (PDMS) with various solvents such as water, ethanol, and iso-propanol, Inverse Gas Chromatography(IGC) at finite concentration, which is a very fast, accurate, and thus promising technique in thermodynamic study of polymer systems, is employed. By measuring the specific retention volumes of the probes, the interaction parameters are calculated by means of the Flory-Huggins equation. From the results, the interaction parameters of the probes are, as expected due to the hydrophobicity of the polymer, found to be of large positive values (2$2.0{\times}10^{-3}mol/g$. For the linear PDMS, interpretation of the space distribution of molecules is performed by the Kirkwood-Buff-Zimm(KBZ) integrals, which give intuitive information about physical properties. From the KBZ integrals, water does not show the tendency of preferential solvation with the PDMS but formed self-cluster. The larger solvent molecules show a stronger tendency to distribute more randomly in the mixture.

• Journal of Soil and Groundwater Environment
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• v.6 no.4
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• pp.83-95
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• 2001

In this study, the contaminated status of groundwater under Ponchon Basin, Kwangju-city was analyzed by hydrogeological survey. Though the distribution of groundwater hydraulic head was similar with the ground elevation, the flow system of groundwater was changed due to overpumping in the industrial area. Paddy field and residential area which were located in the north part of the basin had relatively high concentrations of Cl, N $a^{+}$ and N $O_3$$^{[-10]}$ in the groundwater. Southern part of the basin which most industrial area occupied had relatively high concentrations of HC $O_3$, $Ca^{2+}$, $Mg^{2+}$ and Zn. Groundwater was contaminated by C $l^{[-10]}$ and N $O_3$$^{[-10]}$ due to the infiltration of domestic sewage and factory wastewater. In the Cl case, C $l^{[-10]}$ had a tendency of distribution over the water shed along with the contaminated source. The drawdown of groundwater due to overpumping caused more vertical movement of contaminant than lateral movement. If the overpumping continues in the industrial area, the groundwater flow system will be more affected and the groundwater will be lowered in the north part of basin. It is clear that contamination by C $l^{[-10]}$ and N $O_3$$^{[-10]}$ due to domestic sewage and factory wastewater will spread through the whole basin area.rea.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.3
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• pp.457-468
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• 2018

To improve understanding of the physico-chemical characteristics of aerosols in the national park and comparing the air pollution between national park and the urban area nearby national park, the aerosol characterization study was conducted in Bukhansan National Park, Seoul, from July through September 2017. Semi-continuous measurements of $PM_{2.5}$ using PILS (Particle Into Liquid System) coupled with IC (Ion Chromatography) and TOC (Total Organic Carbon) analyzer allowed quantification of concentrations of major ionic species($Cl^-$, $SO_4{^{2-}}$, $NO_3{^-}$, $Na^+$, $NH_4{^+}$, $K^+$, $Mg{^{2+}}$ and $Ca{^{2+}}$) and water soluble organic carbon (WSOC) with 30-minute time resolution. The total mass concentration of $PM_{2.5}$ was measured by T640 (Teledyne) with 5-minute time resolution. The black carbon (BC) and ozone were measured with a minute time resolution. The timeline of aerosol chemical compositions reveals a strong influence from urban area (Seoul) at the site in Bukhansan National Park. Inorganic aerosol composition was observed to be dominated by ammoniated sulfate at most times with ranging from $0.1{\sim}32.6{\mu}g/m^3$ (6.5~76.1% of total mass of $PM_{2.5}$). The concentration of ammonium nitrate, a potential indicator of the presence of local source, ranged from below detection limits to $20{\mu}g/m^3$ and was observed to be highest during times of maximum local urban (Seoul) impact. The total mass of $PM_{2.5}$ in Bukhansan National Park was observed to be 10~23% lower than the total mass of $PM_{2.5}$ in urban area (Gireum-dong and Bulgwang-dong, Seoul). In general, ozone concentration in Bukhansan National Park was observed to be similar or higher than urban sites in Seoul, suggesting additional biogenic VOCs with $NO_x$ from vehicle emission were to be precursors for ozone formation in Bukhansan National Park.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.36-43
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• 2020

The extracts of antioxidants, torreya nucifera and alphinia henryi, were tested for properties as a fragrance material and applied to a mask pack formulation to study the fragrance properties. The DPPH antioxidant test of hot water and ethanol extract confirmed that the ethanol extract had superior antioxidant efficacy compared to the hot water extract. It was confirmed that the optimal mixing ratio as a raw material for the mask pack of torreya nucifera and alphinia henryi was 3:7 as a result of the DPPH antioxidant test. As a result of the cytotoxicity test, the cell viability was good as it showed 103.30% at 0.5 ug/mL, 104.25% at 1 ug/mL, 102.56% at 5 ug/mL, and 99.17% at 10 ug/mL compared to the untreated group. As a result of the patch test on the mask pack formulation, the skin irritation index of 0.02 was judged as a non-irritation product in the skin irritation primary stimulation human application test. In the evaluation of skin moisturizing, it showed a significant increase rate of 19.178% compared to before the sample adaptation. Evaluation of the change over time in the sheet mask pack formulation confirmed the formulation stability without viscosity and pH change for 12 weeks at low temperature(4℃), room temperature(25℃), and high temperature(45℃).

• Membrane Journal
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• v.25 no.4
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• pp.352-357
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• 2015

To determine the pervaporation separation characteristics of 1-butanol/water mixtures, PEI/PDMS hollow fiber membrane module commercialized by Airrane Co. was subjected to both lab and pilot tests. The 1% 1-butanol of 1-butanol/water feed mixture was used. The flux of $133g/m^2hr$ and separation factor of 23.4 at $30^{\circ}C$ were obtained whereas the $505g/m^2hr$ and 5.1 were measured at $50^{\circ}C$. When compared with the performance of the hollow fiber PDMS membrane by Nagasep Co., the higher flux of $10{\sim}20g/m^2hr$ was obtained by the module of Airrane Co. In order to realized the durability of Airrane Co. module, the long-term test of 35 days has been conducted and as a result, the flux $510{\sim}520g/m^2hr$ and separation factor 20~25 were maintained with the initial values.

• Journal of the Korea Concrete Institute
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• v.28 no.3
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• pp.317-328
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• 2016

This research intends to understand the impact of super-absorbent polymer (SAP) as an internal curing agent in Ultra-High Performance Concrete (UHPC). Two different types of SAPs of acrylic acid (SAP_AA) and acrylic acid-co-acrylamide (SAP_AM) were examined with UHPC formulation. Isothermal calorimetry and x-ray diffraction experiments revealed the impact of polymers with the different chemical bonds on cement hydration. To test its feasibility as a shrinkage reducing admixture for UHPC, a series of experiments including flowability, compressive strength, rapid chloride permeability and autogenous shrinkage profile was performed. While both SAPs showed a reduction in autogenous shrinkage, it has been concluded that the SAP size and chemical form significantly affect the performance as an internal curing agent in UHPC by controlling cement hydration and porosity modification. Between the tested SAPs, SAP_AM which absorbs more water in UHPC than SAP_AA, shows better mechanical and durability performance.