• 한국의류학회지
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• 제17권3호
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• pp.347-358
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• 1993

Graft copolymerization of MMN4-VP onto cotton fiber using Ce(IV) salt as an initiator and triton X-100 as an emulsifier was performed under various polymerization conditions. In cograft polymerization, the polymeization behavior according to variation of 4-VP feed composition and the characteristics of MMA/4-VP graft polymer such as affinity for acid dye owing to cationization of cotton, antibacterial activity and thermal behavior were investigated. The results of this study were as follows : 1. While in copolymerization of MMA and 4-VP, 4-VP content in copolymer was more than that of monomer feed composition. 2. Increasing 4-VP content, graft yield was decreased, but graft efficiency was increased. In case of MMA/4-VP graft polymerization, the highest graft yield was obtained at higher CAN concentration than in MMA graft polymerization, the reason is that the behavior of 4-VP was disturbed by Ce(IV) sail 3. Elevation of temperature resulted in increase of graft yield and the apparent activation energy of MMA/4-VP graft polymerization was higher than that of MMA graft polymerization. 4. MMA/4-VP grafted cotton fiber showed affinity for acid dye, antibacterial activity and higher moisture regain than MMA grafted cotton fiber. MMA/4-VP grafted cotton fabric showed improvement of wrinkle recovery up to 40~50% graft yield and decreased thereafter. MMA/4-VP and MMA grafted cotton fabric did not showed significant difference in wrinkle recovery and stiffness.

• Journal of Pharmaceutical Investigation
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• 제28권2호
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• pp.121-126
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• 1998

The solubility and physicochemical stability of caroverine hydrochloride (CRV), an antispasmodic, in buffered aqueous solutions were studied using a reverse phase high performance liquid chromatography. The solubilty of the drug at pH 2.76-5.40 was similar at the range 31.9-36.2 mg/ml $(34^{circ}C)$, but, at the pH higher than 6.0, markedly decreased. The use of polyethylene glycol 400 as a cosolvent did not increase the solubility at any compositions examined. Moreover. increasing molar concentration of aqueous phosphate buffer from 0 to 0.5 M remarkably decreased the solubility. The degradation of CRY followed the apparent first-order kinetics. The degradation was accelerated with decreasing pH and increasing storage temperature. The half-lives for the degradation of CRY (1.0 mg/ml) at pH 1.28. 4.01 and 5.93 $(45^{\circ}C)$ were 2.8, 31.4 and 124 hr. respectively. The pHs of incubated solutions were to some extent lowered perhaps due to the formation of acidic degradation products. The addition of disodium edetate (0.01%) to the CRY solution (pH 4.95) retarded 2.5 times the degradation rate at $45^{\circ}C$, but the use of sodium bisulfite (0.1%) accelerated 2.9 times the rate. The activation energy for the CRY solution (20 mg/ml. pH 5.4) containing 0.01% EDTA was calculated to be 5.98 kcal/mole. When the solution was stored under nitrogen displacement in ampoule, there was no significant degradation even after 3 months at $40^{\circ}C$, indicating that protection from oxidation by air (oxygen) is essential for the complete stabilization of CRY solution.

• 한국안전학회지
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• 제9권4호
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• pp.29-41
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• 1994

High temperature tensiles tests, steady state creep tests, internal stress tests and creep rupture tests using Al 7075 alloy were performed over the temperature range of 9$0^{\circ}C$~50$0^{\circ}C$ and stress range of 0.64~17.2(kgf/$\textrm{mm}^2$) in order to investigate the creep behavior and predict creep rupture life From the apparent activation energy Qc and the applied stress exponent n measured, at the temperature range of 9$0^{\circ}C$~l2$0^{\circ}C$, the creep deformation seemed to be controlled by cross slip. On the other hand at the temperature of 20$0^{\circ}C$~23$0^{\circ}C$ the creep deformation seemed to be controlled by dislocation climb but at 47$0^{\circ}C$~50$0^{\circ}C$, by diffusion creep. And the rupture life(t$_{f}$) might be represented by anthermal process attributed to the difference of the applied stress dependence of Internal stress and the ratio of the Internal stress to the applied stress, the thermal activated process attributied to the temperature dependence of the internal stress. Also the ratio between stress dependence of primary creep rate and that of minimum creep rate was measured 0.46, the minimum creep rate is expected to be appromately obtained from master creep curve including the relationship primary creep rate and minumum creep rate. Finally the relationship new rupture parameter and logarithmic stress was represented with including the ratio between the dependence of primary creep rate and that of minimum creep rate, using the new rupture parameter the rupture life predition is exactly expected.d.

• Journal of Microbiology and Biotechnology
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• 제15권2호
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• pp.239-246
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• 2005

Some characteristics of two forms of glucoamylase (glucan 1 A-$\alpha$-glucosidase, EC 3. 2. I. 3) purified from Aspergillus coreanus NR 15-1 were investigated. The enzymes were produced on a solid, uncooked wheat bran medium of A. coreanus NR 15-1 isolated from traditional Korean Nuruk. Two forms of glucoamylase, GA-I and GA-II, were purified to homogenity after 5.8-fold and 9.6-fold purification, respectively, judged by disc- and SDS-polyacrylamide gel electrophoresis. The molecular mass of GA-I and GA-II were estimated to be 62 kDa and 90 kDa by Sephadex G-1OO gel filtration, and 64 kDa and 91 kDa by SDS-polyacrylarnide gel electrophoresis, respectively. The optimum temperatures of GA-I and GA-II were 60$^circ$C and 65$^circ$C, respectively, and the optimum pH was 4.0. The activation energy (Ea value) of GA-I and GA-II was 11.66 kcal/mol and 12.09 kcal/mol, respectively, and the apparent Michaelis constants (K_{m}) of GA-I and GA-II for soluble starch were found to be 3.57 mg/ml and 6.25 mg/ml, respectively. Both enzymes were activated by 1 mM Mn^{2+} and Cu^{2+}, but were completely inhibited by 1 mM N­bromosuccinimide. The GA-II was weakly inhibited by 1 mM p-CMB, dithiothreitol, EDTA, and pyridoxal 5-phosphate, but GA-I was not inhibited by those compounds. Both enzymes had significant ability to digest raw wheat starch and raw rice starch, and hydrolysis rates of raw wheat starch by GA-I and GA-II were 7.8- and 7.3-fold higher than with soluble starch, respectively.

• 공업화학
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• 제4권1호
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• pp.94-102
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• 1993

제올라이트 A의 결정화 과정에서 온도, $Na_2O$와 $SiO_2$ 조성의 영향을 조사하였다. 각 결정화 조건에서 결정화 곡선과 최종 생성물의 결정크기 분포를 조사하고 반응 경로 모델을 이용하여 결정화 속도를 구하였다. 결정화 과정은 길이 성장 속도상수가 결정 크기와 무관하게 일정하고 무정형 고형 겔과 용해된 반응물이 평형을 이룬다는 가정으로 잘 모사되었으며, 실험결과와 비교하여 길이성장 속도상수 등을 결정할 수 있었다. 온도가 높아지면 길이성장 단계와 용해된 반응물의 분율이 커져서 결정화 속도가 커졌다. 반면 $Na_2O/H_2O$ 몰비가 커지면 성장단계는 촉진되지 않으나 용해된 반응물의 분율이 커졌으며 핵심생성이 촉진되었다. $SiO_2/Al_2O_3$ 몰비에 따라 용해된 반응물 분율과 핵심생성 속도가 달라진다. 각 결정화 조건에서 제올라이트 A의 길이성장 속도상수는 $0.07{\sim}0.24{\mu}m{\cdot}min^{-1}$로 추정되었으며 겉보기 활성화에너지는 $49kJ{\cdot}mol^{-1}$이었다.

• 한국식품과학회지
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• 제22권6호
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• pp.646-650
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• 1990

마늘의 장기저장 및 새로운 향신료 개발의 일환으로 마늘을 착즙한 후 농축시켜 저장 및 중간 향신 소재화 하고자 하였으며, 그 연구의 일환으로 마늘 착즙 및 그 농축액의 rheological properties에 대해 연구하였다. 마늘 착즙 및 농축액의 흐름거동은 고형물 농도$50^{\circ}Brix$까지는 power-law model에 대체로 잘 적용되었으나 $60^{\circ}Brix$ 이상의 농도에서는 항복응력을 고려한 Herschel-Bulkley model이 더 적절한 것으로 여겨졌으며, 의가소성 유체(pseudoplastic fluid)의 특성을 나타내었다. 고형물 농도 $32{\sim}60^{\circ}Brix$, 온도 $15{\sim}65^{\circ}C$의 범위에서 유동지수는 $0.6130{\sim}0.9937$로 온도가 상승할 수록 증가하였으며, 이 때 점조도지수는 $3.1886{\sim}0.0041Pa\;s^n$였다. 마늘 착즙의 겉보기점도는 전단속도의 증가에 따라 직선적으로 감소하였으며 유동에 따른 활성화에너지는 $11,216{\sim}23,195\;kJ/kg\;mol$이었다.

• 대한화학회지
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• 제19권1호
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• pp.53-64
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• 1975

Co$Cl_2$-THF-MMA계에 대한 중합반응을 조사한 결과 다음과 같은 사실을 알았다. 즉 중합시간에 따른 중합변화율이 6${\sim}$7% 미만의 초기에는 직선적인 관계가 있으나 차차 중합속도가 감소했다가 그 후에는 라디칼중합의 경우와 같이 자동가속화현상을 볼 수 있었다. 개시물인 염화 코발트(II)의 농도가 증가하면 중합속도가 증가했다가 약 $3.4{\times}10^{-4}$mole/l 이상이 되면 반대로 중합속도는 감소하였다. 그리고 단위체인 MMA의 농도에 따라 중합속도는 1.38의 반응차수를 가지고 증가하였다. 라디칼중합에 대한 억제물인 DPPH를 첨가하면 억제기간이 생기고 이 억제기간은 DPPH의 농도에 따라 증가하였다. 이 중합계에 대한 겉보기 총 활성화 에너지는 13.2kcal/moe임을 알았다. MMA($M_1$)과 styrene($M_2$)의 공중합체에 대한 단위체 반응성비는 $r_1$=2.35, $r_2$=0.78이었다. 그리고 이러한 실험결과에서 이 계에 의한 중합개시 메카니즘을 논의하여 디라디칼에 의한 중합이 우세하게 일어난다고 생각되었다.

• 한국식품과학회지
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• 제28권3호
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• pp.538-544
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• 1996

미생물이 생산하는 생물 고분자의 기능성 당색 및 용도 재발 연구의 일환으로. Bacillus sp.의 알카리 발효에 의해 생합성된 점성의 생물 분자의 리올로지 특성을 다른 미생들 다당 및 식뮬 다당류와 비교하면서 검토하였다. 1% 정제 고분자 용액은 xanthan gum 및 guar gum과 마찬가지로 항복응럭을 갖는 의가소성 유체의 거동을 널었다. 유동지수(n)값은 0.41 - 0.75로 전단속도 의존성을 보였으며, 점조도지수(K)값은 0.87 Pa $s^n$으로 guar gum보다는 작고 xanthan gum 보다는 컸다. 그러나 항복응력 (${\tau}_y$)값은 2.28Pa로 xanthan gum이나 guar gum보다 크게 낮았다. 또 정제고분자의 점조도지수(K)값은 지수 함수식에 따르는 농도 및 온도 의존성을 나타내었다. 농도 의존성은 기울기가 서로 달라지는 두 개의 직선관계를 나타냈으며, 농도가 증가에 따라 의가소성은 강해졌다. 시료 용액은 온도 의존성이 매우 낮은 특징을 나타내었고, 유동의 활성화에너지지는 1.16kcal/g mol이었다. 겉보기 점도는 pH와 염의 변화에 매우 불안정함을 나타내었으나 유기용매에 대하여는 어느 정도 안정함을 보였고, 점증제를 첨가하였을 때 겉보기 점도의 상승효과는 관찰되지 않았다.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2352-2358
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• 2012

A high-nitrogen energetic salt, 1-amino-1-hydrazino-2,2-dinitroethylene guanidine salt [G(AHDNE)], was synthesized by reacting of 1-amino-1-hydrazino-2,2-dinitroethylene (AHDNE) and guanidine hydrochloride in sodium hydroxide aqueous solution. The theoretical investigation on G(AHDNE) was carried out by B3LYP/$6-311+G^*$ method. The thermal behaviors of G(AHDNE) were studied with DSC and TG-DTG methods, and the result presents an intense exothermic decomposition process. The enthalpy, apparent activation energy and pre-exponential constant of the process are $-1060J\;g^{-1}$, $148.7kJ\;mol^{-1}$ and $10^{15.90}s^{-1}$, respectively. The critical temperature of thermal explosion of G(AHDNE) is $152.63^{\circ}C$. The specific heat capacity of G(AHDNE) was studied with micro-DSC method and theoretical calculation method, and the molar heat capacity is $314.69J\;mol^{-1}K^{-1}$ at 298.15 K. Adiabatic time-to-explosion of G(AHDNE) was calculated to be a certain value between 60-72 s. The detonation velocity and detonation pressure were also estimated. G(AHDNE) presents good performances.

• Archives of Pharmacal Research
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• 제4권2호
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• pp.109-115
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• 1981

In the present investigation, an attempt has been made to apply the methods of classical chemical kinetics to the hydrolytic reaction of pipethanate hydrochloride. By successively keeping all but one variable essentially constant, it has been possible to resolve the overall effect of the individual contributing factors. Since nearly all commercial pipethanate preparations are formulated with antacid, studies were made at several constant hydrogen ion concentration ranging pH 0.4 to 7.5. Rate measurement was also carried out in temperature ranging from $25^{\circ}C$ to $60^{\circ}C$. The hydrolysis of pipethanate is found to be of first order with respect to pipeethanate concentration over an experimental range of hydrogen ion concentration (pH 0407.5). The apparent activation energy(Ea) at pH 7.5 is 18.30 Kcal/mole and the frequency factor is $1.1408 {\times}10^{9}sec^{-1}$. The rate of the hydrolysis has a minimum at pH 2.5-3.5. In this region the half-life of pipethanate was about15.3 days at $60^{\circ}C$. The catalytic effect of water was found to be $K_{H_2O}$ = $3.16{\times}10^{-5}min^{-1}$ at $60^{\circ}C$. The catalytic constants of the hydroxyl ions and hydrogen ions at $60^{\circ}C$ were also found to be $K_{OH}$ = $4.5519{\times}10^{-5}min^{-1}$ and $K_{H}+$ = $1.1568{\times}10^{-2}min^{-1}$, respectively. This reaction appears to be primarily base catalyzed hydrolysis and pipethanate is relatively reluctant toward acid catalyzed hydrolysis. A positive primary salt effect was noted in the solution of phpethanate at pH 7.5 and at $60^{\circ}C$.