• Macromolecular Research
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• v.16 no.1
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• pp.76-80
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• 2008

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.4
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• pp.405-412
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• 2012

In the past, a very popular way to reduce the corrosion rate of zinc was the use of chemical conversion layers based on $Cr^{+6}$. However, the use of chromium salts is now restricted because of environmental protection legislation. Previous research investigated the optimum corrosion resistance of galvanized steel treated with an organic/inorganic solution containing Si. The result showed that the optimum corrosion resistance occurred by heat treatment of $190^{\circ}C$ in 5 min. In this study, one organic and three hybrid organic/inorganic coating solutions were applied to cold-rolled (CR) carbon steel. The coatings were then evaluated for corrosion resistance under a salt spray test. The coating solutions examined in this study consisted of urethane-only, urethane-Si, urethane-Si-Ti, and urethane-Si-Ti-epoxy. The results of the 7 h salt spray test showed that the urethane-Si-Ti and urethane-Si-Ti-epoxy coating solutions had superior corrosion resistance on CR steel.

• The Journal of Natural Sciences
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• v.7
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• pp.83-90
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• 1995

The microstructural and textural development during rolling is compared in two Hadifield's steels (high Mn steel), one having low carbon content (0.65 wt.%) and the other high carbon (1.35 wt.%).In low carbon Hadfield's steel (LCHS) mixed microstructures are formed which contain intrinsic stacking faults, deformation twins, and brass type shear bands. The deformation twins are thought to be formed by the stacking of intrinsic stacking faults. The similar development to 70-30 brass texture is observed in early deformation. However the abnormal texture is developed after 40 % deformation, which is thought to be due to the martensite phase transformation. In high carbon Hadfield's steel (HCHS) mixed substructures of dislocation tangles, deformation twins, and shear bands (both copper and brass type) are found to develop. The texture development is similar to that of 70-30 brass. This is consistant with no carbon segregation and no martensitic phase transformation in HCHS. In spite of the difference of substructure and texture development during rolling in two steels, the difference in stacking fault energy is measured to be small ($2 mJm^-2$). The carbon segregation is only occurred in LCHS. Thus it is thought that the carbon segregation influence the microstructure and texture development during rolling. This is related with martensite phase transformation in LCHS.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.6
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• pp.497-507
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• 2015

Real-time and quantitative measurement of the chemical composition in ambient aerosols represents one of the most challenging problems in the field of atmospheric chemistry. In the present study, time resolved application by Aerosol-into-Mist System (AIMS) following by total organic carbon analyzer (TOC) has been developed. The unique aspect of the combination of these two techniques is to provide quantifiable water soluble organic carbon (WSOC) information of particle-phase organic compounds on timescales of minutes. We also demonstrated that the application of the AIMS method is not limited to water-soluble organic carbon but inorganic ion compounds. By correlating the volume concentrations by optical particle sizer (OPS), water soluble organic carbon can be highly related to the secondary organic products. AIMS-TOC method can be potentially applied to probe the formation and evolution mechanism of a variety of SOA behaviors in ambient air.

• Carbon letters
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• v.16 no.2
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• pp.93-100
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• 2015

Surface modified carbon felts were utilized as an electrode for the removal of inorganic ions from seawater. The surfaces of the carbon felts were chemically modified by alkaline and acidic solutions, respectively. The potassium hydroxide (KOH) modified carbon felt exhibited high Brunauer-Emmett-Teller (BET) surface areas and large pore volume, and oxygen-containing functional groups were increased during KOH chemical modification. However, the BET surface area significantly decreased by nitric acid ($HNO_3$) chemical modification due to severe chemical dissolution of the pore structure. The capability of electrosorption by an electrical double-layer and the efficiency of capacitive deionization (CDI) thus showed the greatest enhancement by chemical KOH modification due to the appropriate increase of carboxyl and hydroxyl functional groups and the enlargement of the specific surface area.

• Journal of environmental and Sanitary engineering
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• v.15 no.1
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• pp.39-45
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• 2000

The purpose of this study was conducted to indentified the fixing quality of $CO_2$, the most important greenhouse effect gas, by microalgae Chlorella ellipsoidea in batch test apparatus. The glass flask of $1.4{\ell}$ culture media which was saturated with 99.99% pure $CO_2$ gas was setted water bath of $25^{\circ}C$, 5000Lux, and seeded 100$m\ell$ algae liquid. We checked the change of inorganic carbon concentration and algae population with time in culture media. The result were next: the growth of algae population relied on aquatic IC(inorganic carbon) concentration. And the pH was increased with decrease of IC concentration. The growth of algae population had positive correalation with $CO_2$ concentration, and the coefficient of correlation was 0.982. The specific growth rate($\mu$) of Chlorella ellipsoidea was 1.104/d, the maximum specific growth $rate({\mu}_{max}$) of 9.21/d, and helf velocity constant($K_s$) of $259mg/{\ell}$ by Monod equation.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.2
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• pp.93-104
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• 2020

As water resources are limited and legal regulations are strengthened, there is a growing need to reuse residuals in WTP(Water Treatment Plant). In this study, membrane filtration system was constructed and its operation method was studied for water quality stabilization and reuse of WTP residuals. The operation parameters were stable for 1 year and 6 months. Membrane fouling was identified as particulate pollution (activated carbon) and inorganic pollution (manganese). The membrane system was operated steadily with raw water of high concentration SS(Suspended solid) containing activated carbon because membrane fouling was reduced by the effect of End-Free type. In the case of inorganic contamination, dissolved manganese eluted by chemicals and acted as a membrane fouling source, and the operating conditions for minimizing membrane fouling. were confirmed by newly developing application methods and types of cleaning chemicals. Based on the results, design parameters for reducing manganese membrane fouling were derived.

• Journal of environmental and Sanitary engineering
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• v.21 no.4 s.62
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• pp.77-86
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• 2006

The water purification was very important in Korea which has not sufficient water resource and while adsorption method among the various methods to eliminate the water pollutants has been widely used by activated carbon. This study was conducted the basic experiment for hall distribution, pH, conductivity, electronic microscope, cation exchange and inorganic materials the adsorption capacity of Korean traditional charcoal which has similar characteristics to activated carbon of organic pollutants. As a result of observing Korean traditional charcoal with electronic microscope, it was found that it has porous structure, oak charcoal has circular structure, pine charcoal has square structure and bamboo charcoal has hexagonal structure, which has high void fraction per unit area because of its thin cell wall structure. As a result of experimenting hall distribution, hall distribution of bamboo high temperature charcoal is high as 0.269cc/g and has the greatest inorganic contents and cation exchange capacity(CEC) which are the important factor of chemical adsorption.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.234-236
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• 2018

기후변화는 더 이상 피할 수 없는 매우 중요한 문제다. 온실가스 중 큰 비중을 차지하는 이산화탄소 배출을 억제하거나 제거하기 위한 많은 연구들이 진행되고 있다. 최근에는 CCS 중 하나인 지중저장(underground storage)의 대안으로 해양에 이산화탄소를 저장하는 기술인 AWL(Accelerated Weathering of Limestone)을 이용한 해양저장(ocean storage)에 대한 연구가 진행되고 있다. AWL은 이산화탄소를 중탄산이온 형태의 농축수로 만들어 해양에 방류하여 희석 저장시키는 방법으로, 대기 중 재방출이 거의 발생하지 않고 배출된 농축수는 해양의 알칼리도를 높여 해양산성화를 방지할 수 있는 장점이 있다. 금회 연구는 AWL에 의한 방법 중 중탄산이온 농축수의 해양방류 시 이산화탄소 등을 포함하는 용존 무기탄소(DIC, Dissolved Inorganic Carbon)의 거동특성을 파악하기 위한 목적으로 수행하였다. 연구대상 해역은 충분한 수심과 작업효율성이 확보되는 울릉도 부근으로 설정하였으며, 거동특성을 파악하기 위하여 표층방류(surface discharge)와 수중방류(submerged discharge)에 의한 물질확산을 계산할 수 있는 CORMIX모형을 채택하였다. 실험결과, 방류 시점으로부터의 희석률을 고려했을 때, 표층방류 시나리오가 농축수 방류에 가장 적합한 방식이라고 사료된다.

• Food Science of Animal Resources
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• v.30 no.3
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• pp.359-364
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• 2010

Lactobacillus acidophilus A12 was isolated from chicken feces for use as an immunostimulating livestock probiotic. The purpose of this study was to optimize the production of L. acidophilus A12 using response surface methodology (RSM). Initially, the influence of growth medium was studied in terms of carbon sources (glucose, fructose, lactose, glycerol, sucrose, ethanol, and mannitol), nitrogen sources (beef extract, yeast extract, malt extract, and tryptone), and inorganic salts ($CaCl_2$, $MgSO_4$, $KH_2PO_4$, $(NH_4)_2SO_4$, $FeSO_4$, and NaCl). Through one factor-at-a time experiment, lactose, yeast extract, and $CaCl_2$ were determined to be the best sources of carbon, nitrogen, and inorganic salt, respectively. The optimum composition was found to be 17.7 g/L lactose, 18.6 g/L yeast extract, and 0.9 g/L $CaCl_2$. Under these conditions, a maximum cell density of 9.33 Log CFU/mL was produced, similar to the predicted value.