• 펄프종이기술
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• 제42권4호
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• pp.64-70
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• 2010

In this study, hemicelluloses were pre-extracted from mixed hardwood chips using sodium hydroxide solution and then they were isolated from pre-extractives by using various solvents. Isolation was conducted by precipitating hemicelluloses with isopropanol, ethanol, 1,4-dioxane, dimethylsulfoxide (DMSO) and potassium hydroxide (KOH), respectively. The precipitate yield on alkali pre-extractives was the highest when hemicelluloses were isolated by DMSO and then precipitated with ethanol. Most precipitates were yellow colored. The efficiency of isolation was evaluated by analysing the characteristics of isolated hemicelluloses. Isolation using DMSO, KOH and 1,4-dioxane ($80^{\circ}C$) showed rather high efficiency. The highest total separation efficiency was about 77% when alkali pre-extractives were reacted with KOH and precipitated with ethanol. The quantity and purity of isolated hemicelluloses were affected by the solvent type.

• 한국결정성장학회지
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• 제8권2호
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• pp.343-349
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• 1998

$TiCL_4$수용액의 탈수 반응에 있어 pH의 영향에 관하여 연구하였다. KOH와 HCl을 탈수 촉진 및 탈수 지연제로 사용하여 실험한 결과 다음과 같은 결론을 얻었다. $TiCL_4$ 수용액과 KOH와의 반응계에서 중화점은 pH 7.4이었으며 중화점 이전에서는 반응 생성물로 polymetatitanic acid의 중합체인 Ti-gel이 생성되고 중화점 이상에서는 재탈수 반응에 의하여 oligomer화가 일어난다. 또한 결정성 potasium titanate는 존재하지 않는다.

• 한국임상수의학회지
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• 제14권2호
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• pp.195-200
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• 1997

In order to compare the pharmacokinetic profiles of enrofloxacin-HCL)ENFLX-HCL) and enrofloxacin-KOH (ENFLX-KOH) after oral administration in broiler chickens, the study was performed. The chickens used in this study weighed $1.82 {\pm}0.2 kg$ and clinically healthy. The dose of intravenous and lral administration was 5 mg per kg of body weight as enrofloxacin. After intravenous injection of enrofloxacin, it showed two-compartment model with the rapid distribution phase and the slow elimination phase. The mean apparent volume of distribution (Vd) was 2.70 l/kg. The mean half-life of elimination and distribution showed 8.26 h and 0.44 h, respectively. The mean area under curve (AUC) was calculated as $19.7 {\mu} g{\cdot} h/ml$. After oral administration of ENFLX-HCL and ENFLX-KOH with a rate of dose 5 mg of enrofloxacin/kg of body weight, Both of the products were showed one-compartment model unlike that of i.v. enrofloxacin standard solution showed the mean bioavailability of 79.64% for the ENFLX-KOG and 86.24% for the ENFLX-HCL. The mean total body clearance of the former was 0.24 l/kg/h and the latter 0.42 l/kg/h. Both enorfloxacin formulations seemed to have good tissue distribution and penetration as indicated by large volume of distribution : 2.72 l/kg for the -KOH and 4.44 l/kg for the -HCL. With the results obtained in this study, ENFLX-HCL could be used in place of its salt form in chickens.

• Carbon letters
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• 제8권2호
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• pp.101-107
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• 2007

Activated carbons were prepared by impregnation of crushed clean date pits in concentrated solutions of phosphoric acid or zinc chloride followed by carbonization in absence of air at $600^{\circ}C$. Steam-activated carbon was prepared by gasifying $600^{\circ}C$-carbonization product at $950^{\circ}C$ to a burn-off = 50%. KOH- activated carbon was prepared by impregnating date pitscarbonization product obtained at $450^{\circ}C$ in concentrated KOH solution followed by carbonization at $840^{\circ}C$. Textural properties of these carbons were determined from nitrogen adsorption at $-196^{\circ}C$ and the chemistry of the carbon surface was investigated by determination and of the surface carbon-oxygen (C-O) groups using bases of variable strength and dilute HCl. The adsorption of endosulphan at $27^{\circ}C$ on all the carbons prepared was undertaken. Adsorption of this pesticide at 32 and $37^{\circ}C$ was also undertaken for steam-activated and KOH-activated carbons. Phosphoric acid-activated carbons and steamactivated carbons are mainly microporous and have high surface concentration of C-O groups of acidic nature. Steamactivated and KOH-activated carbons exhibited surface areas > 1000 $m^2/g$ and contain micro and non-micrpores. The adsorption of endosulphan was related to the surface area of non-micropores and was retarded by the high concentration of surface C-O groups. The thermodynamic properties indicated the feasibility of the adsorption process and the possible regeneration of the carbon for further use.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.433-436
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• 2005

The Fly-ash makes an Alumino-silicate gel when it mixes an alkali or a silicate solution. This Alumino-silicate gel is produced to the activation of an alkali silicate. And this act to the binder and makes a combine of particles. This study involved mechanical strengths of an Alumino-silicate Gel based the Fly-ash with an alkali solution. NaOH, KOH were utilized to an alkali solution. The alkali solution concentration was varied from 6 to 12M and the some added also the Meta-kaolin, Waterglass so that it made high the mechanical performance. Based on the experimental result, the compressive strengths increased as the quantity of the Meta-kaolin increased. And a mechanical strengths appeared according to the concentration of an alkali solution so that it was different. XRD, FT-IR have been used to characterize mechanical performance.

• 한국결정성장학회지
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• 제12권6호
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• pp.329-334
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• 2002

아나타제형 $TiO_2$, 분말과 $Ca(OH)_2$ 분말을 출발물질로 하여 광화제로 KOH 및 NaOH를 각각 첨가한 후, 오토클레이브 내에서 수열반응시켜 perovskite구조를 갖는 $CaTiO_3$, 분말을 제조하였다. $CaTiO_3$, 분말 합성 시 광화제의 종류 및 농도에 따른 결정상 변화와 입자 형상 및 크기를 고찰한 결과, 광화제로 1 N KOH 용액을 사용한 경우, 약 0.7$\mu$m 크기의 구형입자가 합성되었고, 10 N KOH 용액을 사용한 경우, 3 $\mu$m 정도의 육면체형 입자로 합성되었다. 광화제인 KOH 농도가 증가함에 따라 구형입자로부터 육면체형 입자로 형상이 변화되었으며, 입자의 크기도 증가하였다. 1 N NaOH 용액을 광화제로 사용한 경우에는 0.5~1 $\mu$m 정도의 구형입자가 합성되었고, 10 N NaOH 용액을 사용한 경우에는 1~4 $\mu$m 정도의 육면체 형상을 갖는 입자와 10$\mu$m 이상인 휘스커형 입자가 혼합된 형상으로 합성되었다. KOH 광화제와 마찬가지로 NaOH 광화제의 농도가 증가함에 따라 육면체 및 휘스커 형상을 갖는 입자로 변화하였으며, 입자의 크기도 아울러 증가하였다. 성분 분석 결과 휘스커 형상의 입자의 경우에는 육면체형 입자에서 관찰된 sodium성분이 검출되지 않았다.

• 한국세라믹학회지
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• 제48권1호
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• pp.99-105
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• 2011

Lead titanate ($PbTiO_3$) powder was prepared from lead nitrate ($Pb(NO_3)_2$) and titania ($TiO_2$) by hydrothermal route. Phase formation process was investigated by observing the phases formed in various experimental conditions like different KOH concentration, reaction temperature and time. $PbTiO_3$ powder was fabricated when the KOH concentration was 0.8M or higher. An intermediate compound, $PbTi_{0.8}O_{2.6}$, was formed at first by a reaction between PbO and $TiO_2$ and changed into $PbTiO_3$ powder with a perovskite crystal structure. A $PbTiO_3$ phase was formed in a shorter time when a KOH concentration was increased from 0.8M to 8M because a driving force for a $PbTiO_3$ formation was increased due to an increase in a degree of supersaturation. And $TiO_2$ (rutile) and $3PbO{\cdot}H_2O$ were observed at room temperature in a 0.8M KOH solution and $TiO_2$(rutile) and PbO (litharge) in a 8M KOH. A $PbTiO_3$phase was also formed in a shorter time at a higher reaction temperature as a reaction temperature influenced the rates for a dissolution and a precipitation.

• 청정기술
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• 제15권1호
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• pp.31-37
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• 2009

본 연구는 하수슬러지 탄화물과 활성화제의 화학적 활성화반응을 이용한 활성탄 제조공정을 다루고 있다. 일반적으로 활성화제로는 알칼리 약품을 이용하는데 본 연구에서는 탄소와 활성화반응이 잘 이루어지는 KOH와 NaOH를 사용하였다. 실험결과, KOH로 제조된 활성탄이 NaOH로 제조된 활성탄보다 요오드 흡착력과 비표면적(BET) 등의 물성이 우수하였다. 하수슬러지 탄화물과 활성화제의 최적 침적비율은 KOH 75 wt%, NaOH 50 wt%임을 알 수 있었다. 5 M 염산용액으로 세척하여 중화시킨 후 증류수로 세정하는 활성탄 세정방법을 사용하였다. 본 연구의 최적 실험조건에서 하수슬러지 탄화물을 이용하여 제조된 활성탄의 경우 BET표면적 값이 약 $600m^2/g$에 이르렀다.

• 자원리싸이클링
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• 제10권5호
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• pp.16-21
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• 2001

자전연소고온반응법(SHS)에 의한 고순도 분말의 제조시에 주로 얻어지는 $Mg^{++}$ 유 부산물로부터 초미분 $Mg(OH)_2$및 MgO분말을 제조하였다 $Mg(OH) _2$제조시 최적의 실험 조건은 0.7M의 $Mg^{++}$ 을 함유하는 pH 1.42의 산침출 용액중에 9M의 KOH를 pH조절제로 첨가한 경우이다. 이때 pH는 약 13.0을 나타내며, 모든 $Mg^{++}$ 이 $Mg(OH)_2$로 침전되었다. $Mg(OH)_2$의 탈수반응을 조사하기 위하여 DSC를 사용하였으며, 그 결과를 하소공정에 사용하였다. MgO분말은 건조된 Mg(OH)2 분말을 $400-450^{\circ}C$로 하소함으로써 제조되었으며, 제조된 $Mg(OH)_2$및 MgO분말의 크기 및 형상은 상용 분말과 유사하였다.

• 한국환경보건학회지
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• 제36권4호
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• pp.337-341
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• 2010

The modified simultaneous differential staining technique, which enables double staining of cartilage and bones, needs to be improved to prevent soft tissues from being damaged during the staining process. Key factors influencing the extent to which soft tissues are damaged include the fixative used, macerating time, potassium hydroxide concentration, incubation temperature and the removal of skin from specimens. Here we describe a protocol that enables the hardening of tissues during bleaching and maceration. We also describe a method for objectively measuring rates of cartilage and bone growth. The use of formalin as a fixative rendered soft tissues more rigid due to the resulting chemical bonds formed between proteins. Blotted specimens were immersed in 1% potassium hydroxide (KOH) and incubated at $37^{\circ}C$ for 1 day (smaller specimens) or 2-3 days (larger specimens). The 1% KOH solution was also used as the diluent solution for the subsequent immersion in a graded series of 30%, 50%, 70%, 90%, 100% glycerol solutions, a procedure that made soft tissues even more transparent and hardened. It was not necessary to remove the skin of specimens shorter than 2 cm, since the macerating solution could easily penetrate their thin skin layer and continuously remove those pigments hindering visibility. Since excessive osmosis is another factor that can damage soft tissues in the macerating process by causing the rupture of those cells not able to withstand the osmotic pressure, here it was minimized by balancing the salt concentration between the interior and exterior of cells with the addition of 0.9% sodium chloride (NaCl) in the macerating solution. Finally, to determine the proportions of cartilage and bone growth, photographs of the stained specimens were taken with a dissecting microscope and sections corresponding to the cartilage and bones were cut out from the printed pictures and weighed. Our results show that this method is suitable for the objective evaluation of bone and cartilage growth.