• 한국의류학회지
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• 제13권1호
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• pp.89-97
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• 1989

Graft polymerization of MMA onto cotton fiber was carried out in two ways, two step graft polymerization and one step emulsion graft polymerization, using tetravalent cerium ion as an initiator. At two step graft polymerization, the first step was the pretreatment of cotton fiber with an aqueous initiator solution and the second was the grafting pretreated cotton fiber in the monomer solution. In case of one step emulsion graft polymerization, MMA was emulsified with SLS in initiator solution. Under the various graft polymerization conditions, graft yield, graft efficiency and from the Arrhenius plot the apparent activation energy were compared. The results of this study were as follows: 1. Graft yield and graft efficiency of emulsion graft polymerization were higher than those of two step graft polymerization. 2. In case of two step graft polymerization, graft yield was affected by the pretreatment time of cotton fiber with an aqueous initiator solution. And graft yield of emulsion graft polymerization was increased with the concentration of emulsifier below cmc of SLS and was decreased thereafter. 3. Elevation of temperature resulted increase in graft yield for both grafting methods. The apparent activation energy of emulsion graft pelymerzation was lower than that of two step graft polymerization. 4. Increased reaction time increased in graft yield, but decreased in graft efficiency. 5. Moisture regain of grafted cotton was decreased with graft yield.

• 한국자동차공학회논문집
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• 제21권6호
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• pp.183-194
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• 2013

Liquid urea based SCR has been used in the market to reduce NOx in the exhaust emission of the diesel engine vehicle. This system has several problems at low temperature, which are freezing below $-12^{\circ}C$, solid deposit formation in the exhaust, and difficulties in dosing system at exhaust temperature below $200^{\circ}C$. Also, it is required complicated exhaust packaging equipment and mixer due to supply uniform ammonia concentration. In order to solve these issues, solid urea, ammonium carbonate, and ammonium carbamate are selected as ammonia sources for the application of solid SCR. In this paper, basic research on reaction rate of three ammonia-transporting materials was performed. TGA (Thermogravimetric Analysis) and DTA (Differential Thermal Analysis) tests for these materials are carried out for various heating conditions. From the results, chemical kinetic parameters such as activation energy and frequency factor are obtained from the Arrhenius plot. Additionally, from test results of DSC (Differential Scanning Calorimeter) for these materials, chemical kinetic parameters using the Kissinger method are calculated. Activation energies of solid SCR from this experiment are compared with proper data of literature study, then obtained data of this experiment are used for the design of reactor and dosing system for candidate vehicle.

• 한국분말재료학회지
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• 제16권1호
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• pp.9-15
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• 2009

Amorphization and crystallization behaviors of $Ti_{50}Cu_{50}Ni_{20}Al_{10}$ powders during high-energy ball milling and subsequent heat treatment were studied. Full amorphization obtained after milling for 30 h was confirmed by X-ray diffraction and transmission electron microscope. The morphology of powders prepared using different milling times was observed by field-emission scanning electron microscope. The powders developed a fine, layered, homogeneous structure with prolonged milling. The crystallization behavior showed that the glass transition, $T_g$, onset crystallization, $T_x$, and super cooled liquid range ${\Delta}T=T_x-T_g$ were 691,771 and 80 K, respectively. The isothermal transformation kinetics was analyzed by the John-Mehn-Avrami equation. The Avrami exponent was close to 2.5, which corresponds to the transformation process with a diffusion-controlled type at nearly constant nucleation rate. The activation energy of crystallization for the alloy in the isothermal annealing process calculated using an Arrhenius plot was 345 kJ/mol.

• 한국수산과학회지
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• 제10권4호
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• pp.213-220
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• 1977

제 1보에서 측정한 해수의 비전도도 값을 사용하여 본 논문에서 저자들이 제안한 식으로부터 얻어진 당량 전도도를 Arrhenius plot 했을 때 활성화에너지, ${\Delta}E$는 압력 및 농도변화에 따라 $3.0\~4.0\;Kcal/mole$ 범위 이었다, 압력변화에 따른 활성화 부피변화의 평균치 측정된 온도와 압력에서 $-0.27\~-1.30\;cm^3/mole$ 범위였다. (염소량이 $6.228\%_{\circ},-1.65\~\;-0.32cm^3/mole;\;9.063\%_{\circ},\;-1.18\~-0.27cm^3/mole;\;11.628\%_{\circ},\;-1.53\~-0.07cm^3/mole;\;14.311\%_{\circ},\;-1.37\~-0.35cm^3/mole;\;16.408\%_{\circ},\;-1.18\~-0.47cm^3/mole;\;19.372\%_{\circ},\;-1.53\~-0.29cm^3/mole$)이들값으로 해수의 성질과 물의구조를 정성적으로 밝힐 수 있었다. 본 논문 정리를 위해 조언하여 주신 원중훈교수님께 감사드립니다.

• 한국산학기술학회논문지
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• 제9권4호
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• pp.1059-1066
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• 2008

열중량반응기와 미분반응기를 이용하여 ABS의 역분해 및 생성물분포 특성을 연구하였으며 미분반응기를 이용한 실험의 열분해온도는 $400\sim450^{\circ}C$이었다. 각 상의 열분해생성물의 수율은 무게측정을 통해 얻었으며 액상생성물의 탄소수분포는 GC-SIMDIS 방법을 통해 측정하였다. 열중량분석실험에서는 측정할 수 없었던 다량의 고상잔류물의 생성을 회분식 미분반응기실험을 통해 확인학 수 있었다. 반응온도와 시간이 증가할수록 액상생성물의 수율과 평균분자량은 감소하였으나 액상생성물 중의 스티렌모노머의 생성은 두드러지게 증가하였다. ABS 열분해 반응에서 말단절단의 속도계수인 활성화에너지 값은 54.1kcal/mole이었다.

• Korean Chemical Engineering Research
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• 제46권3호
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• pp.540-544
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• 2008

혼합플라스틱에 대한 열분해특성실험을 스테인레스 스틸의 회분식 미분반응기에서 수행하였으며, 혼합플라스틱의 혼합비율은 22 wt.% HDPE, 17 wt.% LDPE, 27 wt.% PP, 12 wt.% PS, 16 wt.% ABS, 6 wt.% PVC이었다. 열분해온도는 $410{\sim}450^{\circ}C$ 이었으며 각 열분해생성물의 수율은 무게측정을 통해 얻었으며, 액상생성물의 분자량분포는 GC-SIMDIS 방법을 통해 측정하였다. 혼합플라스틱 열분해의 경우 반응온도와 시간이 증가할수록 고상잔류물의 수율증가와 액상생성물의 수율감소 그리고 액상생성물의 평균 분자량 감소가 두드러졌다. 혼합플라스틱에 포함된 PVC의 약 20%가 염소가스형태로 배출됨을 알 수 있었다. 혼합플라스틱 열분해에서 말단절단의 속도계수인 활성에너지 값은 50.2 kcal/mole 이었다.

• 한국식품영양과학회지
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• 제21권3호
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• pp.279-285
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• 1992

황산암모늄 분획 (35-60%) 효소액을 사용하여 Aspergillus fumigatus IFO 5840의 cytidine deaminase에 대한 효소학적 성질을 조사하였다. 효소반응의 전처리시간은 25분이었으며 본 효소의 최적pH와 최적온도는 각각 6.8-7.2와 $37^{\circ}C$부근이었다. PH에 대한 안정성은 pH7.2에서 9.0의 범위에서 안정하였으며 온도의 안정성은 4$0^{\circ}C$에서 10분 열처리시 대체로 안정하였으나 6$0^{\circ}C$에서 20분간 처리시는 77%의 효소실활을 나타내었고 7$0^{\circ}C$에서 25분간 처리하였을때 완전히 실활되었다. 본 효소의 활성화 에너지 값(Ea)은 14.190kca1/mo1이었고 온도계수 ($Q_{10}$ )는 2.163이었다.

• Bulletin of the Korean Chemical Society
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• 제23권11호
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• pp.1595-1603
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• 2002

In this paper we have presented the results of diffusion behavior of model systems for eight liquid n-alkanes ($C_{12}$-$C_{44}$) in a canonical (NVT) ensemble at several temperatures using molecular dynamics simulations. For these n-alkanes of small chain length n, the chains are clearly <$R_{ee}^2$>/6<$R_g^2$>>1 and non-Gaussian. This result implies that the liquid n-alkanes over the whole temperatures considered are far away from the Rouse regime, though the ratio becomes close to the unity as n increases. Calculated self-diffusion constants $D_{self}$ are comparable with experimental results and the Arrhenius plot of self-diffusion constants versus inverse temperature shows a different temperature dependence of diffusion on the chain length. The global rotational motion of n-alkanes is examined by characterizing the orientation relaxation of the end-to-end vector and it is found that the ratio ${\tau}1/{\tau}2$ is less than 3, the value expected for a isotropically diffusive rotational process. The friction constants ${\xi}$of the whole molecules of n-alkanes are calculated directly from the force auto-correlation (FAC) functions and compared with the monomeric friction constants ${\xi}_D$ extracted from $D_{self}$. Both the friction constants give a correct qualitative trends: decrease with increasing temperature and increase with increasing chain length. The friction constant calculated from the FAC's decreases very slowly with increasing temperature, while the monomeric friction constant varies rapidly with temperature. By considering the orientation relaxation of local vectors and diffusion of each site, it is found that rotational and translational diffusions of the ends are faster than those of the center.

• 한국식품영양과학회지
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• 제17권4호
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• pp.283-289
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• 1988

변온조건하에서 보리가루를 저장하였을 때 수분활성에 따른 avaible lysine의 손실을 반응속도론적으로 고찰한 결과 Avalilable lysine은 일차반응으로 감소하였으며 반응속도는 수분활성과 저장온도가 높을수록 빨랐고, 각 수분활성에서의 활성화 에너지는 $6.02{\sim}10.32Kcal/mole$, $Q_10$치는 $1.34{\sim}1.65$였다. Acelerated shelf-life test로부터 구한 $25^{\circ}C$에서의 shelf-life는 $60{\sim}216$일의 범위였으며 온도와 수분활성이 증가함에 따라 단축되었다. 변온조건에서의 실측치와 예측치를 비교한 결과 유효온도차는 $1.21{\sim}2.23^{\circ}C$였고 shelf-life는 실측치와 예측치가 약간 차이를 나타내었다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 추계종합학술대회
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• pp.995-998
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• 2003

MOCVD 법을 이용하여 TiO$_2$ 박막을 제작하여, 투과곡선을 비교적 간단하게 분석할 수 있는 포락선방법을 사용하여 기판온도에 따른 TiO$_2$ 박막의 굴절률, 소광계수 등의 광학적 상수들을 구하였다. 투과곡선의 모사를 실시하여 포락선방법으로 구한 값들이 매우 신뢰도가 높음을 입증하였다. TiO$_2$ 박막은 35$0^{\circ}C$ 에서 부터 결정화가 되기 시작하여, 40$0^{\circ}C$ 이상에서 tetragonal structure 를 갖는 anatase 상으로 완전히 결정화됨을 알 수 있다. 기판온도에 따른 증착률을 Arrhenius plot 하여 구한 활성화에너지는 reaction limited 단계에서 17.8 kcal/mol 이었다. 포락선방법을 이용하여 구한 TiO$_2$ 박막의 굴절률 (λ=632.8 nm) 은 기판온도가 40$0^{\circ}C$ 에서 $600^{\circ}C$ 로 증가함에 따라 2.19 에서 2.32 로 증가하는 추세를 나타내었고, 소광계수는 0.021 에서 0.007로 감소하는 경향을 나타내었다.