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        검색결과 128

        62.
        1998.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Surface active properties of these aqueous Gemini surfactant solutions including surface tension, critical micelle concentration(cmc), foaming power, foam stability, emulsifying power and Krafft point were measured at given conditions. They showed excellent properties, being compared with conventional single-chain surfactants such as sodium dodecyl sulfonate(SDS). Their surface tensions in the aqueous solutions were decreased to 30~38 mN/m, which is lower than 39 mN/m of SDS, and their cmc values evaluated by surface tension method were 2.8×10-5~3.3×10-4 mol/L. These values were also much lower than that of SDS, 9.8×10-3 mol/L. The foaming power and foam stability, especially decyl and dodecyl compounds, were good and the emulsifying power in benzene or soybean oil was also excellent. All of the synthesized Gemini surfactants possessed good water solubility and their Krafft points were all below 0℃. As results, DDED and DDOD, Gemini surfactants which were synthesized are expected to be applied as foamers, emulsifiers and so on.
        4,000원
        63.
        1998.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Novel type surfactants containing two long-chain hydrophobic alkyl groups and two hydrophilic sulfonate groups were successfully synthesized by reactions of ethylene glycol diglycidyl ether with long-chain fatty alcohols, after then by reactions with 1,3-propane sultone and sodium hydride under THF solvent. All these compounds, so called Gemini surfactants, were purified by thin layer chromatography and column chromatography. Their structures were identified by FT-IR and 1H-NMR.
        4,000원
        64.
        1998.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        카올린을 용해시킨 황산용액을 에탄올에 주입함으로써 알루미늄황산염의 침전물, AI2(SO4)3·18H2O을 제조하고, 그것의 열분해거동을 검토하였다. 합성된 고순도의 침전물은 약 2μm크기의 판상형태의 입자들로 구성되어져 있었다. 에탄올속으로 카올린을 용해시킨 황산용액의 주입속도를 증가시킴에 따라서 생성된 침전물의 결정사 크기는 감소하였다. 침전물의 탄수 및 탄황산에 대한 겉보기 활성화에너지는 각각 11.9Kcal mol-1 과 48.2kcal mol-1 이었다.
        4,000원
        65.
        1996.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The rhamnan sulfate extracted from green algae seaweed, Monostroma nitidum was characterized as activity in vitro culture assay with macrophages from mice. Rhamnan sulfate indicated that F-4-3 fraction enhanced glucose consumption, as well as the production of nitrogen dioxide and tumor necrosis factor(TNF). F-4-3 fraction was also augmented IL-1 secretion from those macrophages. Effects of the pretreatment of peritoneal macrophages with rhamnan sulfate F-4-3 fraction and several polysaccharides as relative standard on the production of H₂O₂ induced with unopsonized zymosan A were examined. Pretreatment with polysaccharides inhibited the zymosan A mediated H₂O₂ production by macrophages. The phorbol myristate acetate (PMA) mediated H₂O₂production was not affected by the pretreament. These result suggested that pretreatment of rhamnan sulfate interfered with the interaction of macrophages zymosan A. Rhamnan sulfate inhibited zymosan A mediated production of H₂O₂ by macrophages and F-4-3 fraction was also activator of macrophages.
        4,000원
        66.
        1996.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        홑파래로부터 황산기를 함유한 다당체를 크로마토그래피로 분리정제하여 rhamnan sulfate가 항보체 활성화에 미치는 영향을 조사하였다. 항보체 활성능력은 F-4-3 획분을 비교군으로 Heparin H-180, Dextran과 비교해 결과 비교군보다 높았고, C4a와 C3a의 convertase의 형성과 기능을 F-4-3 획분이 억제하였다. 이러한 보체 활성화 양식은 classical pathway 및 alternative pathway로도 경유함을 알 수 있었다.
        4,000원
        69.
        1995.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate the removal of ammonium nitrogen by biological nitrification in raw water containing LAS using BAC. At batch teats, LAS removal by ozone followed the first order reaction, and the rate constants(k) by ozone dose 1, 3mg/min.L were $0.040min^{-1}$, $0.062min^{-1}$ respectively. Therefore, the more ozone was dosed, the higher LAS was removed The reaction between ozone and ammonium nitrogen also followed the first order, and rate constants(k) at pH7,8 and 9 were $8.9{\times}10^{-4}min-1$, $3.8{\times}10^{-3}min^{-1}$, and $2.9{\times}10^{-2}min^{-1}$ respectively at ozone dose of 3mg/min.L . Therefore, ammonium nitrogen was little removed by ozone under neutral pH of 7. The continuous flow apparatus had four sets composed of a ozone contacter and a GAC column. Through continuous filtration test for 50days, the following conclusions were derived; (1) LAS was removed 23%, 30% respectively by ozone dose 1, 3mg/L, and was not detected in all column effluents during the period of experiment. Therefore, it appeared that adsorption capacities of each column still remained. (2) Ammonium nitrogen concentration after ozone contact varied little in raw Water because pH of raw water was from 6 to 7, and was transfered to nitrite and nitrate within GAC columns as the result of staged nitrification. After 30days, nitrite was not detected in all column effluents due to biological equilbrium between nitro semonas and nitrobacter Average removals of ammonium nitrogen in each column after the lapse of 30days were the following; ${\cdot}$ column A (ozone dose 3mg/L, EBCT 9.5min): about 100% ${\cdot}$ column B (ozone dose 1mg/L, EBCT 9.5min): 91% ${\cdot}$ column C (ozone dose 3mg/L, EBCT 14.2min): about 100% ${\cdot}$ column D (ozone dose 0mg/L, EBCT 9.5min): 53% Though column A and C reached nitrification of about 100%, column C (longer EBCT than column A) was more stable than column A. (3) After backwash, nitrification reached steady state within 5 to 8 hours. Therefore, nitrification was not greatly affected by backwash. (4) According to the nitrification capacity in depth of column A, C, where 100% nitrification occured. LAS was removed within 20cm, while ammonium nitrogen required more depth to be removed by nitrification.
        4,200원
        70.
        1993.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This experiment was conducted to investigate the effects of concentrated sulfate on the germination rate, growth rate and the productivity of weight of kudzu (Pueraria thwnbergiana Bentham). The germination rate of kudzu seed by one or two treatment retre
        4,000원
        73.
        1992.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        점토 광물로부터 황산 처리법을 이용하여 수화 황산 알루미늄을 제조하였다. 하동 카올린 을 황산 처리하였을 때 수화 황산 알루미늄 형성에 미치는 카올린의 하소 온도와 하소 시간, 산처리 반응 온도와 반응 시간 및 황산의 농도의 영향을 조사하였다. 또한, 황산 처리된 용액으로부터 수화 황산 알루미늄이 석출되는 최적 조건을 구하였으며, 생성된 수화 황산 알루미늄을 상온에서 1200˚C 까지 각각의 온도 구간에서 열처리한 분말에 대해서 XRD, TG-DTA, FT-IR, SEM, 입도 분석 및 불순물 분석을 하였다. 최적 조건 하에서, 카올린 중의 알루미나가 수화 황산 알루미늄으로 생성되는 전화율은 약 60%였고, XRD, TG-DTA, FT-IR 등의 분석 결과로 부터 생성된 수화 황산 알루미늄의 열분해 반응은 Al2(SO4)3·18H2O→Al2(SO4)3·6H2O→Al2(SO4)→ amorphous alumina→γ-alumina→δ-alumina→θ-alumina→α-alumina이었다. 또한 생성된 수화 황산 알루미늄을 1200˚C에서 하소 하여 얻은 알루미나 분말의 순도는 99.99%였다.
        4,000원
        76.
        2022.06 KCI 등재 서비스 종료(열람 제한)
        본 연구는 자연계에서 가장 흔하게 관찰되는 두 그린 러스트(green rust) 광물인 carbonate green rust (CGR)과 sulfate green rust (SGR)을 공침법(co-precipitation)을 통해 각각 합성하고, 이들의 형성 메커니즘 및 이화학적 특성들을 체계적으로 규명하였다. X-선 회절(XRD) 분석 및 리트벨트 정련 수행 결과, 본 합성 조 건에서 이차광물상 없이 이중층수산화물로서 CGR과 SGR이 합성됨을 확인하였다. 또한, 각각의 구조 파라미 터는 CGR의 경우 a(=b)축 = 3.17Å, c축 = 22.52 Å이고, SGR의 경우 a(=b)축 = 5.50Å, c축 = 10.97 Å이며, 이 들의 미결정 크기는 각각 (003)면 기준 57.8 nm와 (001)면 기준 40.1 nm로 밝혀졌다. 주사전자현미경/에너지 분산형 분광분석(SEM/EDS) 결과, CGR과 SGR은 모두 육각 판상의 전형적인 이중층수산화물 결정 형상을 보이지만 탄소(C)와 황(S)의 함량은 서로 다르게 나타났다. 퓨리에 변환 적외선(FT-IR) 분광 분석결과, 탄산 염(CO3 2-)와 황산염(SO4 2-) 이온들이 각각 CGR과 SGR의 층간 음이온으로 밝혀졌고, 이는 XRD를 활용한 광 물상 동정 결과와 잘 일치한다. 철 용액으로의 수산화이온(OH-) 주입 시간에 따른 혼합 용액의 pH와 Eh, 그 리고 잔류 철 농도의 비율(Fe(II):Fe(III)) 측정 결과, 시간에 따른 차이는 있지만 두 green rusts 모두 1단계 전구체 형성, 2단계 중간 생성물로의 상변환, 그리고 3단계 green rust로의 상변환과 에이징에 의한 결정성장 으로 이어지는 결정 형성 메커니즘을 보이는 것으로 판단된다. 본 연구는 공침법을 통해 CGR과 SGR을 안 정적으로 합성하고 이들의 형성 메커니즘과 이화학적 특성을 규명함으로써, green rust를 활용한 응용 연구 및 산업 활용에 원천 기초자료를 제공할 것으로 기대된다.
        77.
        2022.01 KCI 등재 서비스 종료(열람 제한)
        In this study, solid-liquid separation conditions for coagulation and sedimentation experiments using inorganic coagulant (aluminum sulfate and Poly-Aluminum Chloride (PAC)) were optimized with brine wastewater discharged by the epoxy-resin process. When the turbidity and suspended solid (SS) concentration in raw wastewater were 74 NTU and 4.1 mg/L, respectively, their values decreased the lowest in a coagulant dosage of 135.0 - 270.0 mg Al3+/L. The epoxy resin was re-dispersed in the upper part of wastewater treated above 405.0 mg Al3+/L. The removal efficiencies of turbidity and SS via dosing with aluminum sulfate and PAC were evaluated at initial turbidity and SS of 74 - 630 NTU and 4.1 - 38.5 mg/L, respectively. They increased most in the range from 135.0 - 270.0 mg Al3+/L. The solid-liquid separation condition was quantitatively compared to the correlation of SS removal efficiency between the coagulant dosage and SS concentration based on the concentration of aluminum ions. The empirical formula,   , shows the relationship between SS removal efficiency (R) and coagulant dosage (D) at 38.5 mg/L; it produced high correlation coefficients (r2) of 0.9871 for aluminum sulfate and 0.9751 for PAC.
        78.
        2019.02 KCI 등재 서비스 종료(열람 제한)
        This study investigates the changes in ammonia fluxes, pH and total nitrogen of liquid ferrous sulfate-treated litter over 5 weeks. A total of 200 broiler chicks (Arbor Acres, 1 d old) was separated into two treatment groups (0 g and 100 g liquid ferrous sulfate/kg litter) with four replications of 25 birds in each group. Liquid ferrous sulfate was sprayed on the litter by using a small sprayer. There was no difference (p>0.05) in the ammonia fluxes observed between the control and liquid ferrous sulfate treatment groups at 0, 1, and 5 weeks, except for 2, 3 and 4 weeks. At 5 weeks, the litter pH and total nitrogen content did not show any difference (p>0.05) between the control and liquid ferrous sulfate treatment groups. In conclusion, the use of liquid ferrous sulfate is not a suitable for use in poultry litter to reduce ammonia and pH or improve the total nitrogen content.
        79.
        2018.12 KCI 등재 서비스 종료(열람 제한)
        There is growing concern over the effects of global warning. In response, the power generation sector must consider a wider range of systems and fuels to generate power. One of the classes of solid fuels that is being increasingly developed is biomass. However, one of the most serious problems that biomass plants face is severe corrosion. To mitigate the problem, various approaches have been proposed in terms of additive utilization. This study is based on the results obtained during the co-combustion of wood chip and waste wood in a circulating fluidized bed boiler (CFBC boiler). The KCl concentration was reduced from 59.9 ppm to 3.9 ppm during the injection of ammonium sulfate, and NOx was reduced by 25.5 ppm from 30.6 ppm to 5.1 ppm. However, SOx increased by 110.2 ppm from 33.2 ppm to 143.4 ppm, and HCl increased by 71.5 ppm from 340.5 ppm to 412.0 ppm. Thus, we confirmed that the attitude of the superheater tube was reduced by 87 ~ 93%, and the injection of ammonium sulfate was effective in preventing high-temperature corrosion.
        80.
        2018.10 KCI 등재 서비스 종료(열람 제한)
        Biomass-fired power plants produce electricity and heat by burning biomass in a boiler. However, one of the most serious problems faced by these plants is severe corrosion. In biomass boilers, corrosion comes from burnt fuels containing alkali, chlorine, and other corrosive substances, causing boiler tube failures, leakages, and shorter lifetimes. To mitigate the problem, various approaches implying the use of additives have been proposed; for example, ammonium sulfate is added to convert the alkali chlorides (mainly KCl) into the less corrosive alkali sulfates. Among these approaches, the high temperature corrosion prevention technology based on ammonium sulfate has few power plants being applied to domestic power plants. This study presents the results obtained during the co-combustion of wood chips and waste in a circulating fluidized bed boiler. The aim was to investigate the characteristics of pollution load in domestic biomass power plants with ammonium sulfate injection. By injecting the ammonium sulfate, the KCl content decreased from 68.9 to 5 ppm and the NOx were reduced by 18.5 ppm, but SO2 and HCl were increased by 93.3 and 68 ppm, respectively.
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