• Polymer(Korea)
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• v.33 no.6
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• pp.608-614
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• 2009

The cation-exchange membrane which was sulfonated styrene-ethylene/buthlene-styrene(SEBS) block copolymer containing the high impact polystyrene (HIPS) was prepared via post-sulfonation and casting method using the epoxidized polybutadiene and divinylbenzene as crosslinking agents. Post-sulfonation was carried out with sulfuric acid as sulfonating agent and silver sulfate as initiator in the nitrogen atmosphere. The basic properties of membranes, degree of sulfonation (DS), water uptake, ion-exchange capacity (IEC), electrical resistance, and modulus have been examined. DS of membrane increased with increasing the sulfonation time. The maximum DS of membrane containing 10 wt% HIPS was 83.6 %. The water uptake and IEC of membranes gradually increased as increasing the DS. The maximum water uptake and IEC of membranes were 43.8 % and 1.14 meq/g, respectively. The lowest electrical resistance of membrane containing the 20 wt% HIPS was $83\;\Omega{\cdot}cm^2$. The electrical conductivity of membrane containing 10 wt% HIPS was $1.22\times10^{-4}S/cm$. The modulus of membrane increased with increasing DS and these values were 153 and $204\;kgf/cm^2$ before and after sulfonation, respectively.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.2
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• pp.63-71
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• 2023

Increased nitrogen in the water system has become an important environmental problem around the world, as it causes eutrophication, algae bloom, and red tide, destroys the water system, and undermines water's self-purification. The most common form of nitrogen in the water system is ammonium ion (NH₄⁺), and the largest portion of ammonium ions comes from wastewater. NH₄⁺ is a major contributor to eutrophication, which calls for appropriate treatment and measures for ammonium removal. This study produced biochar by applying Sorghum × drummondii, a type of biomass with a great growth profile, analyzed the adsorption capacity of Sorghum × drummondii biochar produced from the changing carbonization temperature condition of 200 to 400℃ in the ammonium ion range of 10 to 100 ppm, and used the results to evaluate its potential as an adsorbent. Carbonization decomposed the chemical structure of Sorghum × drummondii and increased the content of carbon and fixed carbon in the biochar. The biochar's pH and electrical conductivity showed high adsorption potential for cations due to electrical conductivity as its pH and electrical conductivity increased along with higher carbonization temperature. Based on the results of an adsorption experiment, the biochar showed 54.5% and 17.4% in the maximum and minimum NH₄-N removal efficiency as the concentration of NH₄-N increased, and higher carbonization temperature facilitated the adsorption of pollutants due to the biochar's increased pores and specific surface area and subsequently improved NH₄-N removal efficiency. FT-IR analysis showed that the overall surface functional groups decreased due to high temperature from carbonization.

• Journal of Environmental Impact Assessment
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• v.22 no.2
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• pp.171-181
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• 2013

In this study, we report the water quality characteristics of pollutants for 4 major tributaries in the Yeongsan and Sumjin river basins using statistical analysis, such as regression equation and factor analysis. The flow rate and water qualtiy data collected from 4 sampling sites(Hwangryoung A, Jiseok A, Chooryeong A, Osu A) in the Yeonsan and Sumjin river basin during the past 3 years were analyzed for 11 parameters(flow rate, dissolved oxgen, pH, water temperature, electric conductivity, biochemical oxygen demand, chemical oxygen deman, total organic carbon, total nitorgen, total phosphorus, suspended solid). The results showed that the concentrations of BOD, COD, TOC, T-N, T-P in Hwangryoung A(HW) and Jiseok A(JS) of the Yeongsan river basin were decreased as the flow rate was increased. This means that rather than nonpoint soources, point sources affect water quality. In the cases of Chooryeong A(CR) and Osu A(OS) in the Sumjin river basin, howerever, nonpoint sources than point sources are an important factor that affects the water quality. Also, the factor analysis technique was employed to analyze principal component influencing on water quality. The results revealed that the first principal component in HW was correlated with EC, DO, T-N, water temperature. This "nitrogen influx according to seasonal pattern" factor may be interpreted. In JS, the first principal component was correlated with BOD, COD, TOC and is likely to represent "organic matter" processes. In CR and OS, BOD, COD, TOC, SS and T-P were significantly correlated and is considered as representing "Organic matter and adsorption of phosphorus on sediments influx". This study is expected to contribute to the effective pollution control/management of the surfac waters in the study sites.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.263-266
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• 2013

It was investigated the electrochemical characteristics of the Ni-MH battery by hydrophilic process. For adopting the Ni-MH battery in water-electrolyte, polyolefin separator was processed the hydrophilic treatment. No treatment sample did not meet KS standard (KSC 8544) but hydrophilic treatment ones satisfied with the KS standard in electrochemical characteristics, such as discharge performance, retention capacity, and cycle performance. All hydrophilic treatment samples showed similar battery performances. Among them, sulfonation treatment sample exhibited the highest value in aspect of capacity retention rate (> 88%). Furthermore, fluoride treatment sample showed the best cycle performance during battery test. This sample maintained a good cycling performance until $1,480^{th}$ cycle, which was about 3 times as compared with that of KS standard (500 cycle).

• Journal of The Korean Society of Grassland and Forage Science
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• v.41 no.4
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• pp.259-266
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• 2021

The present study was aimed to estimate the effect of ensiling period and bacterial inoculants on chemical compositions and fermentation characteristics on rye silage harvested at delayed stage. Rye (Secale cereale L.) was harvested after 20 days of heading stage (29.4% dry matter, DM). The harvested rye forage was applied with different inoculants following: applications of distilled water (CON), Lactobacillus brevis (LBB), Leuconostoc holzapfelii (LCH), or mixture of LBB and LCH at 1:1 ratio (MIX). Each forage was ensiled into 20 L mini bucket silo (5 kg) for 50 (E50D) and 100 (E100D) days in triplicates. The E50D silages had higher in vitro digestibilities of DM (IVDMD, p<0.001) and neutral detergent fiber (IVNDFD, p=0.013), and lactate (p=0.009), and acetate (p=0.011) than those of E100D, but lower pH, lactic acid bacteria (LAB), and yeast. By inoculant application, LCH had highest IVDMD and IVNDFD (p<0.05), while MIX had highest lactate and lowest pH (p<0.05). The CON and LCH in E50D had highest LAB and yeast (p<0.05), whereas LBB in E100D had lowest (p<0.05). Therefore, this study concluded that LCH application improved the nutrient digesbility (IVDMD and IVNDFD) of lignified rye silage, and longer ensiling period for 100 days enhanced the fermentation characteristics of silage compared to ensiling for 50 days.

• Journal of Environmental Science International
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• v.25 no.2
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• pp.231-238
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• 2016

In this study, we have investigated to find optimal pre-treatment flocculation condition by analyzing the floc growth rate with mixing conditions and the membrane permeation flux for pre-treatment step of the membrane process. The higher mixing intensity showed a constant floc size index (FSI) values, and lower mixing intensity increased the degree of dispersion of the FSI values. Results of comparing the distribution characteristics of the FSI value and the permeation flux were more effective in increasing flux when the FSI values were 0.2 or higher. The degree of dispersion of FSI was relatively large in 40 rpm mixing condition compared to 120 rpm. In 40 rpm mixing condition, it decreased the permeation flux compared to 120 rpm because various sizes of flocs were distributed. Coagulation-UF membrane process enhanced 30%~40% of the flux rate compare to UF alone process, and the coagulation-MF process increased up to 5% of the flux rate compare to MF alone process. Pre-treatment, that is, coagulation process, has been found to be less effects on relatively larger pore size for MF membrane. For UF membrane, the flux was a little bit same when applying only the rapid mixing process or rapid mixing with slow mixing processes together. In case of MF membrane, the flux was improved when rapid mixing process applied with slow mixing process together.

• Membrane Journal
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• v.12 no.4
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• pp.255-261
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• 2002

Poly(vinyl alcohol) (PVA) membranes crosslinked with poly(acrylic acid-co-maleic anhydride) (PAM) as a polymeric crosslinking agent were prepared to investigate the pervaporation performance for the dehydration separation of aqueous ethanol solution. The characteristics of the resulting membranes crosslinked(x) were analysed by FT-IR and water swelling test. The water swelling decreased with increasing crosslinking agent content. The crosslinked PVA membranes with PAM showed lower water swelling than those of PVA membrane crosslinked with glutaraldehyde and modified PVA membrane. The swelling of water molecules in the crosslinked PVA membranes is more restricted by both chemical crosslinking between PVA and polymeric crosslinking agent chains and physical crosslinking by the entanglement between the PVA and polymeric crosslinking agent chains. For the pervaporation of aqueous ethanol solution through the crosslinked membrane, as the contents of crosslinking agent increased, the separation factor increased while the permeation flux decreased. The separation factor slightly decreased and permeation flux increased with increasing feed water content. As a result it could be considered that PVA-PAM membranes suppressed the plasticization effect even in the range of high water concentration in fled.

• Journal of Korean Society on Water Environment
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• v.36 no.2
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• pp.137-147
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• 2020

A direct contact membrane distillation (DCMD) was applied to treat strong nitrogenous wastewater of anaerobic digestion supernatant (ADS) and human urine (HU). The ammonia transfer was evaluated in terms of specific ammonia transfer (SAT) value, which is the ratio of total ammoniacal nitrogen divided by the amount of water transferred. The acidification resulted in low SAT values and high quality of produced water. The ammonia transfer control in the acidic condition was stronger for HU than ADS due to higher alkalinity (pH 8.8) and ammonia concentration (5700 mg-N/L) of HU. Acidified HU at pH 4 exhibited a SAT value of 1.64 × 10^-5, which was significantly smaller than the SAT value of 3.00 × 10^-3 for the original HU. The low pH enhanced the water flux for ADS, but HU showed a steep decrease in water flux due to enhanced fouling. It was considered that the fouling intensity in acidic conditions depends on the characteristics of the wastewater source. The major foulants on the MD membrane were NaCl, CaCO₃ and CuSO₄ as recognized by the SEM-EDS. Acidified ADS and HU at pH 4 showed relatively high N content of 8.18 % and 28.03 %, respectively, as organic fouling.

• Nuclear Engineering and Technology
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• v.48 no.4
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• pp.952-964
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• 2016

The prototype generation IV sodium-cooled fast reactor (PGSFR) has been developed by the Korea Atomic Energy Research Institute. This reactor uses sodium as a reactor coolant to transfer the core heat energy to the turbine. Sodium has chemical characteristics that allow it to violently react with materials such as a water or steam. When a sodium-water reaction (SWR) occurs due to leakage or breakage of steam generator tubes, high-pressure waves and corrosive reaction products are produced, which threaten the structural integrity of the components of the intermediate heat-transfer system (IHTS) and the safety of the primary heat-transfer system (PHTS). In the PGSFR, SWR events are included in the design-basis event. This event should be analyzed from the viewpoint of the integrities of the IHTS and fuel rods. To evaluate the integrity of the IHTS based on the consequences of the SWR, the behaviors of the generated high-pressure waves are analyzed at the major positions of a failed IHTS loop using a sodium-water advanced analysis method-II code. The integrity of the fuel rods must be consistently maintained below the safety acceptance criteria to avoid the consequences of the SWR. The integrity of the PHTS is evaluated using the multidimensional analysis of reactor safety-liquid metal reactor code to model the whole plant.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.1
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• pp.97-105
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• 1994

To investigate the characteristic and the cause of the yellow water zones in the estuary of keum River, physico-chemical measurement and analyses were made on seawater samples collected from 18 stations in May, July, august, October in 1992, and February in 1993 respectively. The yellow water zones were recorded as grade 9 on the forel water color meter and appeared consistently at the stations 1, 2, 3, 4, 5, 7, 8, 9, 13, 14, 15 and 17 through out the year. The organically polluted matter gradually increased in the study area. The nutrient concentrations of inner waters of water zones were higher than that of the surrounding waters and were over red tide criteria levels. But abnormal aggregation of phytoplanktons could not occur because of lack of light and high current velocity. In Conclusion, this yellowish colored water zone was caused not by abnormal aggregation of phytoplanktons but by inorganic matters such as sand or soil particles, $85\%$ of which consisted of suspended solids.