• Korean Chemical Engineering Research
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• 제54권2호
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• pp.171-174
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• 2016

효소 전극 cathode와 PEMFC용 전극 anode를 이용하여 효소연료전지를 구동하였다. 효소 cathode는 그래파이트 분말과 효소로서 Laccase, 산화환원 매개체로서 ABTS를 혼합해 압축해서 만들고 Nafion 이오노머로 코팅하였다. cathode 제조조건을 변화시키며 OCV를 측정해 효소 cathode 제조 최적조건을 찾았다. 효소 cathode 압축 시 최적 압력은 4.0 bar 였다. 효소 cathode에서 그래파이트가 95%일 때 최고의 OCV를 나타냈다. cathode기질 용액의 최적 글루코스 농도는 0.4 mol/l이었다.

• 공업화학
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• 제17권3호
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• pp.317-320
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• 2006

본 연구에서는 HCI프로그램을 이용하여 여섯 가지 퓨린 유도체(caffeine, guanine, hypoxanthine, purine, theobromine, and theophylline)의 최적 분석 조건을 결정하였다. 이동상으로 물과 메탄올을 사용하는 역상 HPLC를 사용하였다. 체류모델로는 Snyder, Langmuir, Binary polynomial 중에서 체류인자를 가장 잘 예측한 Binary polynomial을 사용하였고 용출곡선을 계산하기 위해서는 단 이론(plate theory)을 사용하였으며 모든 계산은 HCI 프로그램을 이용하여 계산하였다. 이동상의 조건은 일정용매조성법(isocratic mode)과 계단함수 구배용매조성법(step-gradient mode)을 이용하였다. 일정용매조성법에서 물과 메탄올의 조성비가 93/7 (v/v)일 때 최적 분석조건을 얻을 수 있었다. 분석시간의 단축을 위하여 계단함수 구배용매조성법을 사용하여 이동상의 조성을 물/메탄올 93/7 (v/v)에서 5 min 후에 75/25 (v/v)로 변경하는 최적조건을 계산했다. 위의 두 조건에서 실험을 수행하여 계산 용출 곡선과 실험값을 비교하였으며, 매우 잘 일치함을 보였다.

• 한국초지조사료학회지
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• 제15권4호
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• pp.274-278
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• 1995

This experiment was conducted to know what does the cutting date have an effect on the chemical composition and nutritive yield of Miscanthus sinensis, in order to determine the optimum cutting date of the plant when it is utilized as roughage. Miscanthus sinensis growing natively in the summit of Sam Ak mountain(550m above sea level) was cut at 10 days intervals from 25 July to 15 October, 1988. Plant length and dry matter contents were generally increased with delayed cutting date. Crude protein contents of the plant cut on 5, 15, and 25 of September were 5.5, 5.2 and 5.1%, respectively. Cmde fiber contents was similar with cutting treatment and averaged 35.6%. Cmde protein yield was higher in September than in other cutting date. Yield of crude fiber were 8.3, 9.3 and 9.3t/ha on 5, 15 and 25 September, respectively. Ratio of Cmde protein yield to Crude fiber yield on 5 September tended to be higher than on 15 September and 25 September. These results suggest that the optimum cutting date of the Miscanthus sinensis for good quality forage seems early September.

• Progress in Superconductivity
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• 제6권1호
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• pp.41-45
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• 2004

Polycrystalline Tl-1223 superconductors with a chemical composition of (Tl, Pb, Bi)TEX>$ (Sr, Ba)<_2$$Ca_2$$Cu_3$$O_{x}$ were synthesized by the solid state reaction method. The optimum chemical composition was $Tl_{0.8}$ $Pb_{0.2}$ $Bi_{0.2}$ $Sr_{1.8}$ $Ba_{0.2}$ $Ca_{2.2}$ $Cu_3$$O_{x}$ And the optimum sintering temperature and time were $905^{\circ}C$ and 7.5h, respectively. The sample was evaluated for their superconducting properties by magnetization measurement. The critical temperature $T_{c}$ is 120 K and the critical current density $J_{c}$ (T=5K, 0T) is estimated to be ∼ $10^{5}$ A/$\textrm{cm}^2$ for $Tl_{0.8}$ $Pb_{0.2}$ $Bi_{0.2}$ $Sr_{1.8}$ $Ba_{0.2}$ $Ca_{2.2}$$Cu_3$$O_{x}$ .

• 한국전기전자재료학회논문지
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• 제11권4호
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• pp.298-305
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• 1998

The PVC membrane electrode for measuring perchlorate ion was developed by incorporating various quaternary ammonium sallts. The effect of chemical structure, the content of active material, the kind of plasticizers, and the membrane thickness on the electrode characteristic such as the linear response range and Nernstian slope of the electrode were studied. It was obtained that the effect of the chemical structure of an active material on the electrode characteristics was improved with increasing the alkyl chain length of the quarternary ammonium salts in the ascending order of Aliquat 336P, TOAP, TDAP, and TDDAP. The optimum membrane composition was 9.09wt% of TDDAP, 30.3wt% of PVC, and 60.6wt% of plasticizer(DBP). And the optimum membrane thickness was 0.45mm at this composition. Under the above condition, the linear response range was $10^{-1}~1.2\times10^{-6}$M, and the detection limit was $5.1\times10^{-7}$M with the Nernstian slope of 57mV/decade of activity of perchlorate ion. The electrode potential was stable within the pH range from 4 to 11. The selectivity coefficient was as shown below: $SCN^->I^-NO_3^->Br^->ClO_3^->F^->Cl^->SO_4^{2-}$

• 한국세라믹학회지
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• 제28권10호
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• pp.793-802
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• 1991

The multicrystalline machinable ceramics was fabricated by melting method using domestic pyrophyllite. After determination of optimum crystallization temperature and time from results of DTA, XRD and SEM, base glasses were heat treated by 2-step schedule. Main crystalline phases identified by XRD, EDX were Na-fluorophlogopite, ${\beta}$-spoduemen and ${\alpha}$-cordierite, and the crystallization condition of these crystals was varied with chemical composition, thermal history and nucleation agents. The thermal, chemical properties of prepared samples were excellent.

• 대한의용생체공학회:의공학회지
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• 제11권2호
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• pp.295-304
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• 1990

In order to use for artificial dental tooth (dental crowens) , new glass-ceramics material has been studied. Its basic composition and the condition of heat treatment for crystalization, mechanical and chemical properties were investigated. Adding of the LAS system composition in the basic glass, time and temperature for crystalization were shortened. Fracture toughness (kic)of samples heat treated at 90$0^{\circ}C$ for 2 hours is 2.5-2.6MN/m3/2, the optimum condition of heat treatment for artificial tooth is A and B samples heating to 75$0^{\circ}C$ for 2 hours, raising to 90$0^{\circ}C$ and maintaining at 90$0^{\circ}C$ for 2 hours and C sample heating to 75$0^{\circ}C$ maintaining at 75$0^{\circ}C$ for 2 hours. In acid and'alkali solution, chemical durability is excellent.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.667-671
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• 2015

Anode는 효소를 이용한 효소전극과 cathode는 PEMFC용 전극을 이용해 효소연료전지를 구동하였다. 효소 anode는 graphite 분말과 효소로서 글루코스 산화제, 전자매개체로 ferrocene을 혼합해 압축해서 만들고 Nafion 이오노머로 코팅하였다. Anode 제조조건을 변화시키며 성능을 측정해 효소 anode 제조 최적조건을 찾았다. 효소 anode 압축 시 최적 압력은 8.89 MPa이고, 효소 anode의 graphite 성분비가 60%일 때 최고의 출력밀도를 나타냈다. Anode 기질 용액의 최적 glucose 농도는 1.7mol/l이었다. 효소 anode는 Nafion 용액에 1초, 2회 침지에 의해 안정화되었다.

• Korean Chemical Engineering Research
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• 제52권6호
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• pp.713-719
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• 2014

4성분계 다중반응이 반응증류 탑 내에서 발생할 때 증류거동의 변화를 시각화 방법을 통해 분석하였다. 시각화 방법이란 단순 증류의 물질수지에 각 반응에 의한 벡터를 추가하고 이를 공간상에 표현하는 것으로 각 단에서 혼합물의 조성 변화 및 반응의 진척도를 직관적으로 알 수 있다. 또한 이를 통해 주어진 운전조건에서 필요한 총 단수 및 최적반응 단의 위치를 결정할 수 있다. 본 연구에서는 에틸렌글리콜(Ethylene glycol) 생산공정을 시각화 방법을 통해 분석하였다. 제안된 시각화 방법을 사용하여 복잡한 실험이나 공정모사 없이 4성분계 다중반응증류 공정에 대한 타당성 평가 및 분석이 가능하다.

• 한국생활과학회지
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• 제18권6호
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• pp.1315-1321
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• 2009

The chemical composition of natural powder dye $Pinux^{TM}$ manufactured from Pinus radiata bark and dyeability of dyed silk fabrics with $Pinux^{TM}$ were examined. It is made up of the optimum dyeing condition of silk fabric according to the dyeing concentration, dyeing time, and dyeing temperature. Also, we examined the colorfastness and antibiosis of dyed silk fabrics to washing, rubbing, perspiration and light. For the analysis of the chemical composition of $Pinux^{TM}$, the total contents of phenolic compound, proanthocyanidin(PA) and anti-oxidative activities of the dye were analyzed. As a result, it was found that the main components of the $Pinux^{TM}$ manufactured from Pinus radiata bark is proanthocyanidin, mostly a flavonoid containing a procyanidin structure, and it consists of approximately 63% phenol. As a result of examining the dyeability of silk fabrics with $Pinux^{TM}$, it showed that the dyeability was best under the conditions of the concentration of dye $1{\sim}1.5%$(wt/v%), dyeing time of 90 minutes, and dyeing temperature at $90^{\circ}C$. It was found that the colorfastness of dyed silk fabrics, colorfastness to washing, perspiration for acidic and rubbing were as good as grade 4 or 4-5. However, the colorfastness to light was low at grade 1, the same as the results of other natural dyed fabrics. As a result of the antibiosis measurement for the $Pinux^{TM}$-dyed silk fabrics, it showed high antibacterial properties to Staphylococcus sureus at 99.6%.