• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2000년도 추계학술대회 논문집
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• pp.384-388
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• 2000

일반적으로 흡착분리공정 기술개발은 대략 3단계의 과정을 거치게 되는데 흡착제의 선정, 흡착탑의 거동해석, 연속공정 구성 및 운전으로 이루어진다. 이중 흡착제의 선정은 대상 혼합물에 어떤 흡착제를 사용하여 효율적인 분리 결과를 얻을 수 있는가를 결정하는 기초단계이면서도 가장 중요한 과정이다. 이를 위해 여러 흡착제에 대한 흡착평형량과 이로부터 얻어지는 선택도, 흡착열, 그리고 흡착질과 흡착제 사이의 물질전달저항과 흡착제의 기공 분포도, 기공부피, 기공율, 비표면적, 충전 밀도(Bulk Density), 파쇄 강도 및 마모저항 등과 같은 물리적 특성을 종합적으로 비교 검토하여 흡착제를 선택하여야 한다. (중략)

• Environmental Engineering Research
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• 제25권4호
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• pp.470-478
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• 2020

Spent coffee grounds (SCG), the residue after brewing coffee beverage, is a promising biodiesel feedstock due to its high oil contents (15-20%). However, SCG should be pretreated to reduce the high free fatty acid content, which hampers transesterification reaction. To overcome this, we explored a direct transesterification reaction of SCG using ultrasound irradiation and identified the optimal sonication parameters. A high fatty acid methyl ester (FAME) content, up to 97.2%, could be achieved with ultrasound amplitude of 99.2 ㎛, irradiation time of 10 min, and methanol to oil ratio of 7:1 in the presence of potassium hydroxide concentration of 1.25 wt.%. In addition, we demonstrated that ultrasound irradiation is an efficient method to produce biodiesel from untreated SCG in a short time with less energy than the conventional mechanical stirring method. The physical and chemical properties of the SCG biodiesel met the requirements for an alternative fuel to the current commercial biodiesel.

• 한국표면공학회지
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• 제53권2호
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• pp.53-58
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• 2020

In this study, we developed plasma electrolytic oxidation (PEO) process for aluminum 7075 alloy to improve the corrosion and mechanical properties. The electrolyte consists of potassium hydroxide and sodium silicate. Additionally, sodium stannate was added into the electrolyte to investigate its effect on PEO film formation. Titanium was used as the counter electrode. Plasma generation voltage reduced from 300V to 150 V by adding 4 g/L of sodium stannate. The thin oxide films were observed by SEM(Scanning Electron Microscopy)/EDS (Energy Dispersive Spectroscopy) for quantitative and qualitative analyses. XRD (X-ray diffraction) and XRF (X-ray Fluorescences) analyses were also carried out to identify oxide layer on aluminum 7075 surface. Vicker's hardness test was performed on the PEO-treated aluminum 7075 surface.

• Carbon letters
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• 제16권2호
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• pp.127-131
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• 2015

In this work, highly porous carbons were prepared by chemical activation of carbonized biomass-derived aerogels. These aerogels were synthesized from watermelon flesh using a hydrothermal reaction. After carbonization, chemical activation was conducted using potassium hydroxide to enhance the specific surface area and microporosity. The micro-structural properties and morphologies were measured by X-ray diffraction and scanning electron microscopy, respectively. The specific surface area and microporosity were investigated by $N_2$/77 K adsorption-desorption isotherms using the Brunauer-Emmett-Teller method and Barrett-Joyner-Halenda equation, respectively. Hydrogen storage capacity was dependent on the activation temperature. The highest capacity of 2.7 wt% at 77 K and 1 bar was obtained with an activation temperature of $900^{\circ}C$.

• 약학회지
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• 제30권2호
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• pp.73-78
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• 1986

Peucedanum terebinthaceum Fischer (Umbelliferae) known as "Gi Reum Na Mool" in Korea and used for the treatment of cough, phlegm, headache and common cold etc. The substances were isolated from the fruits of Peucedanum terebinthaceum and identified by UV, GLC, IR, NMR, Mass spectra and physico-chemical tests. The steroidal compounds from the fruits were identified as $\beta$-sitosterol (tR 33.01 min.) and stigmasterol (tR 28.87 min.) by GLC. Substance I (colorless prismatic crystal, $C_{19}H_{20}O_5$, mp $110~111^{\circ}$) was identified as decursin which is one of the pyranocoumarin. Hydrolysis of substance I with 5%-potassium hydroxide produced decursinol. Acetylation of decursinot gave its monoacetate, white needles, $C_{16}H_{16}O_5$. Substance II(light yellowish white needle crystal, $C_9H_6O_3$, mp $227~228^{\circ}$) was proved to be umbelliferone. Substance I, decursin, was isolated for the first time from the fruits of Peucedanum spp. (Umbelliferae).

• 대한화학회지
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• 제16권2호
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• pp.93-99
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• 1972

To obtain the various kinds of inositol stereomers, we have selected the process of electrolytic reduction of DL-epi-inosose-2 using Ni, Ta, Cu, Mo, Pb, Sn, W, Cd and Hg etc., as cathode. We think that this process gives greater variety than chemical processes. DL-epi-inosose-2 was synthesized by chemical oxidation of myo-inositol, dissolved in aqueous solution of potassium hydroxide, and used as electrolytic solution. To prevent anodic oxidation of cathode products the H-type diaphragm cell was used. As the results of paper chromatography of cathodic products, we obtained the $R_f$ values of myo-inositol and epi-inositol were in good agreement with literature values.

• 한국균학회지
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• 제6권1호
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• pp.5-8
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• 1978

Attempts were made to investigate on the fatty acids of Agaricus bisporus, a cultivated edible mushroom. Fats were extracted from it and saponified with alcoholic potassium hydroxide. Isolated fatty acids were methylated and were subjected to column chromatography and G.L.C. Eleven saturated fatty acids, i.e., dodecanoic, tridecanoic, tetradecanoic, pentadecanoic, hexadecanoic, heptadecanoic, octadecanoic, eicosenoic, uncosenoic, docosenoic, and tricosenoic acids, were identified. Especially palmitic and stearic acids were abundant. Nine unsaturated fatty acids appear to exist in the carpophore.

• 한국응용과학기술학회지
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• 제18권4호
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• pp.298-305
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• 2001

Emulsified transesterification of soybean oil into biodiesel was investigated using potassium hydroxide and sodium methoxide catalysts with methyl glucoside oleic polyester as a methanol-in-oil emulsifier. The transesterification reaction conditions were optimized to obtain high yields of fatty acid methyl esters of the quality defined by biodiesel standards. The developed process resulted in $95{\sim}96%$ of overall yield from soybean oil by alkali-catalyzed methanolysis at $45^{\circ}C$ of reaction temperature with 6:1 of methanol-to-oil molar ratio and 1(v/v)% methyl glucoside oleic polyester in the presense of 0.8wt% KOH and 1.2wt% $NaOCH_{3}$.

• 한국세라믹학회지
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• 제38권11호
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• pp.959-961
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• 2001

Nanosized CeO$_2$Powders were prepared under high temperature and pressure conditions by precipitation from metal nitrates with aqueous potassium hydroxide. Spherical shape of CeO$_2$powder was obtained at 175$^{\circ}C$ for 6h. TEM and X-ray diffraction patterns showed that the synthesized particle was crystalline. The average size and size distribution of the synthesized particles were below 30 nm and narrow, respectively. In addition, the effects of synthesis parameters under hydrothermal process are discussed.

• 한국세라믹학회지
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• 제23권4호
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• pp.11-16
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• 1986

$BaTiO_3$ ceramics powder was prepared by coprecipitation method either in oxalic acid solution or in potassium hydroxide solution. Thermal decomposition of coprecipitated $BaTiO(C_2O_4)_2$.$4H_2O$ powder in oxalic acid solution was investigated by means of Themogravimetry Differential Thermal Analysis and X-ray Diffraction Analysis. Low temperature decomposition of coprecipitated $BaTiO(C_2O_4)_2$.$4H_2O$ caused narrow particle size distribution whereas high temperature decomposition caused fairly wide particle size distribution by partial sintering. As the reaction time increased the average particle size of coprecipitated $BaTiO_3$ powder in KOH solution was increased. The most narrow paticle size distribution was obtained when the coprecipi-tates were ripened for 4hrs.