• Journal of the korean veterinary medical association
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• v.5 no.2
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• pp.56-57
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• 1961

• Journal of the Korean Ceramic Society
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• v.34 no.3
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• pp.323-329
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• 1997

Particle growth of BT-oxalate was investigated in aging with various additives such as glycerine, chloro-form and NaCl. Their effects on size and morphlogy of particle was examined. It can be known that particle size distributions of BT-oxalate precipitate varied with amounts of these additivies. With small amounts of these additives, particle growth of nonuniform distribution was occurred, but above 1 mole percent of those additives, uniform size distributions of about 0.4 ${\mu}{\textrm}{m}$ could be obtain. There was little difference among the effects by the kinds of additives. From the decomposition of uniform BT-oxalate, BaTiO3 powders of about 0.3${\mu}{\textrm}{m}$ could be obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.162-162
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• 2008

세리아는 고체 산화물 연료전지(SOFC, solid oxide fuel cell)의 전해질 재료와CMP( chemical mechanical polishing) 슬러리 재료, 자동차의 3원 촉매, gas sensor, UV absorbent등 여러 분야에서 사용되고 있다. 본 연구에서는 세리아의 입자의 크기와 형상을 조절하여 성능 및 물성을 향상시켜 보다 넓은 분야의 활용을 하고자 실험을 실시하였다. 세리아 합성에 사용되는 전구체인 cerium carbonate의 특성이 세리아 분말의 물리화학적 특성에 직접적인 영향을 주기 때문에 전구체의 합성 단계에서 형상과 크기를 조절하고자 하였다. 세륨염으로 cerium nitrate hexahydrate, 균일침전반응을 할 수 있는 urea를 침전제로 사용하였다. 반응 용매의 유전상수를 조절하고 반응의 과포화도 변화를 이용하기 위하여 에탄올을 첨가하여 입자의 크기 및 형상을 조절, cubic형태의 $Ce_2O(CO_3)_2{\cdot}H_2O$ 결정상을 가지는 세리아 전구체를 합성하였다. 이렇게 생성된 전구체를 $1000^{\circ}C$에서 2시간동안 하소하여 세리아를 합성하고 반응시간, 농도, 에탄올의 함량 변화에 대해 XRD, FE-SEM, particle size analyzer, micropore physisorption analyzer 분석을 통하여 입자의 결정상과 형상, 입도 분포 및 기공분포 등을 반응인자의 변화에 따라 비교 및 해석하였다.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.161-164
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• 2011

본 논문에서는 MBR 공정 유출수의 화학응집에 따른 특성을 알아보고자 A2O공정 하수처리수를 대상으로 막의 공극 크기와 약품 교반시간 및 응집 침전시간에 따른 인 제거 효율을 조사하였다. 막 여과 전후의 시료에 대한 응집실험결과 막 여과 전후의 응집제 투입에 따른 인 제거효율은 막 여과 전 90%와 비교했을 때 각각 74.5, 71.2, 62.6%로 최고 37.4%까지 큰 차이를 보였으며 이것은 막 여과로 인하여 시료 내 존재하는 콜로이드성 물질들의 입자 크기가 작아져 응집반응을 위한 응집핵 형성에 영향을 주었기 때문이며 막의 공극 크기가 작을수록 인 제거 효율도 감소하는 것으로 나타났다. 완속교반과 침전시간을 길게 할수록 인 제거 효율이 증가하였다. 침전시간이 10분일 경우는 인 제거 효율이 막 여과 후의 시료에 대해서 각각 45.3, 35.1, 52.0%로 인 제거가 상당히 불안정하였고 60분일 경우에는 각각 83.4, 85.1, 80.7%로 탁월한 인 제거가 일어난 것을 알 수 있었다.

• Resources Recycling
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• v.23 no.3
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• pp.21-29
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• 2014

This study was conducted to obtain the basic data for designing the lithium recovery process from the "salar de Uyuni" in Bolivia. For this study, the mock brine which has the similar chemical composition with the brine of "salar de Uyuni" was prepared, and the effects of reaction factors such as temperature, time, pH and so forth on the precitation reaction of magnesium hydroxide were investigated.

• Korean Journal of Food Science and Technology
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• v.22 no.3
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• pp.319-324
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• 1990

The effects of pH, protein and fat content, addition of emulsifiers, stabilizer, sugar, salt and calcium salt on the stability of soymilk suspension were investigated by analyzing the cream separated and precipitates of soymilk which is prepared by various conditions. In the alkaline region of pH, soymilk showed a good stability of the suspension and particularly, above pH 10, precipitates were not formed. When 1.5% of palm oil with 0.4% of glycerine monostearate was added to soymilk in the hydrophile-lipophile balance (HLB) value of 4 to 7, resulted maximal emulsion stability occured below H LB 6. The stability was decreased with increasing the fat concentration and soy oil showed better emulsion stability than that of palm oil. Among the commercial stabilizers, 0.03% of carrageenan was most effective. The stability was not decreased by addition of sugar up to 3% while it was decreased by addition of sodium salt and calcium salt at low level.

• Economic and Environmental Geology
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• v.37 no.1
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• pp.133-142
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• 2004

The purpose of this study is to evaluate a laboratory test on arsenic removal effciency for ARD(Acid Rock Drain-age) using limestone and apatite, and on heavy metals removal efficiencies for AMD(Acid Mine Drainage) using apatite and fish bone. As a result of the laboratory test, pH, arsenic removal rate of limestone & apatite are inversely proportional to flow rates and apatite removes 100% of arsenic while limestone removes 37% of arsenic at 0.6$m{ell}$/min/kg flow rate in case of ARD treatment. And the dissolution amount of apatite is twenty five times higher than that of limestone. In case of AMD treatment, fish bone shows higher dissolution rate than apatite, and pH of outlet water reacted with fish bone is higher than that reacted with apatite. The heavy metal removal rates of fish bone are also higher than that of apatite except arsenic removal rate. The precipitate resulted from fish bone reaction with AMD seems to be biological sludge type while that resulted from apatite with AMD is inorganic solid which can settle easily compared with the biological sludge and can be cemented by gypsum. As the results, apatite can be used as a precipitant for the polluted mine waters showing wide range of pH and fish bone can be used for highly contaminated AMD.

• Journal of the Korean GEO-environmental Society
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• v.23 no.9
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• pp.33-40
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• 2022

Sedimentation and pH neutralization has been investigated as preteatment of acid contaminate water. The settling and neutralizing process derive more effective degradation efficiency as the pre-treatment process before the removal process of adsorption, volatile, biodegradation, or oxidation. Settling velocity, uniformity coefficient, coefficient of curvature, and grain size index can define in the sedimentation process for characteristics of the soil. The stainless steel sieve has been used to separate each particle size of the dry soil by assembling in order of 4, 10, 20, 40, 80, 100, and 200 mesh sizes. The soil from Gamcheon Port in Busan drops upper side of the sieve and shakes back and forth to separate each different size of the particle. The 1L of Imhoff cone and 200 mL of the mass cylinder were used as settling tanks to calculate settling velocity. Stokes' equation was used to figure out the average density of dry soil with a value from settling velocity. In the results, the average particle density and lowest settling velocity were 1.93 g/cm³ and 0.11 cm/s, respectively. These values can detect the range of settling points of sediment to prevent chemical accidents. In pH neutralization, the initial pH of 2, 3, 4, and 5 of nitric acid and sulfuric acid are used as an acid solution; 0.1, 0.01, and 0.001 M of sodium hydroxide and calcium hydroxide are used as a base solution. The main goal of this experiment is to figure out the volume percentage of the acid solution becomes pH 7. The concentration of 0.001 M of base solution exceeds all the conditions, 0.01 M exceeds partially, and 0.1 M does not exceed 5 v/v% except pH 2. Calcium hydroxide present less volume than sodium hydroxide at pH neutralization both sulfuric and nitric acid.

• Clean Technology
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• v.6 no.1
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• pp.27-38
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• 2000

A physicochemical process called Ultra Rapid Coagulation(URC) can dramatically remove organics, metals, and phosphates in wastewater by adding weighted coagulation additive(WCA) and recycling sludge into the coagulation basin to increase the growth rate and adsorption ability of floc. Also this process can improve floc settling rate than conventional coagulation process and reduce the pollutants loaded into the receiving water for securing water source. It was evaluated that WCA and sludge added have effects on the removal efficiency and estimated the possibilities of reusing the effluent from this process.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.227-230
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• 2004

본 연구에서는 유류오염토양 세척유출수내 미세토사의 효율적 제거를 위한 최적의 방안 및 적용 운전 조건을 도출하고자 하였다. 응집제를 주입하지 않은 blank 실험결과, 광운대학교 토양 세척유출수는 pH 7～12의 범위에서 65～75%의 효율을 나타내었고, 우이천 하천퇴적 토양 세척유출수는 pH 7～11의 범위에서 30% 안팎의, pH 12에서는 70% 정도의 낮은 효율을 나타내었다. pH 13에서는 두 가지 세척유출수에서 각각 91%, 85%의 효율을 나타내었다. 응집ㆍ침전 실험 결과, 광운대학교 토양 세척유출수는 FeC13, alum, PAC을 적용하였을 때 대체로 99% 이상의 효율을 보였으나, PAM을 적용하였을 때는 pH 13에서만 약 95%의 효율을 보였을 뿐 pH 7～12의 범위에서는 50～70%의 낮은 효율을 보였다. 우이천 하천퇴적 토양 세척유출수는 alum과 PAC을 적용하였을 때 대체로 90% 이상의 효율을 나타내었으나, FeC13와 PAM을 적용하였을 때는 pH 13일 경우에서만 98%이상의 효율을 보였을 뿐 다른 pH조건에서는 대체로 60%이하의 효율을 보였다. 두 가지 세척유출수에 대하여 높은 효율을 보인 alum과 PAC의 경제성을 비교해본 결과 같은 양의 세척유출수를 응집처리 할 경우 PAC에 비하여 alum을 적용하였을 때 적은 비용이 소요되었다. 따라서 alum이 효율성과 경제성에서 가장 우수함을 알 수 있었다.