• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.428-434
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• 2016

In this study, benzyltrialkylammonium chlorides with different alkyl chain length were synthesized and applied to liposome. Prepared cationic surfactant embedded liposomes were measured particle size, zetapotential, release property and antibacterial activity. The average particle size of liposomes was 120~140 nm. As alkyl chain length was increased, the liposome size was increased. Zetapotential for the solution of liposomes added cationic surfactants were in the range of +80~90 mV. In release test, collagen release rate could be controlled by alkyl chain length. liposome embedded long alkyl chain surfactant had enhanced sustained release property. Entrapment efficiency of hydrophilic collagen were 25.9~27.5%.

• Korean Journal of Food Science and Technology
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• v.27 no.1
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• pp.105-111
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• 1995

The relationship betwwen the molecular structure of amylopectin and the texture of cooked rice was investigated using Korean rice [3 varieties of Japonica type and 3 varieties of Tongil type(Japonica-Indica breeding type)]. The molecular structure of rice amylopectin was polymodal and distributed A chain of $\overline{DP}$ 12.4, short B chain of $\overline{DP}$ 20.6, B chain of $\overline{DP}$ 26.3, long B chain of $\overline{DP}$ 45 and super long chain of above $\overline{DP}$ 55. The super long chain of amylopectin was composed of long linear chain with poorly branched chain. Also, the super long chain of amylopectin showed positive correlated with average chain length, inherent viscosity and ${\beta}-amyloysis$ limit$({\%})$, but negative correlated with ${\lambda}max$ of iodine reaction of amylopectin. The structural properties of amylopectin in Japonica type were different from those of amylopectin in Tongil type. In relationship between molecular structure of amylopectin and texture of cooked rice, the average chain length, inherent viscosity, ${\beta}-amyloysis$ limit and super long chain of amylopectin was showed a positive correlation with hardness, but a negative correlation with adhesiveness of cooked rice. The long chain of rice amylopectin is the less, the eating quality of cooled rice was the better. These results suggest that the molecular structure of rice amylopectin could be responsible for the texture of cooked rice.

• Elastomers and Composites
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• v.47 no.4
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• pp.329-335
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• 2012

In this study, we synthesized poly(ethylene-ter-high ${\alpha}$-olefin-ter-p-methylstyrene) using Zr metallocene catalyst/borate type cocatalyst system. Various effects of the high ${\alpha}$-olefin (1-hexene, 1-octene, 1-decene, and 1-dodecene) were observed. The structure and composition of the terpolymers were characterized using $^{13}C$ NMR and $^1H$ NMR. Catalytic activity, polymer yield, molecular weight and molecular weight distribution were analyzed according to the chain length of high ${\alpha}$-olefin. We determined morphology, crystallinity and thermal properties of the terpolymers.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.696-701
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• 2003

Rice seeds of 4 cultivars including Whachung and Nampung, of the non-waxy rice cultivars, and Shinsunchalbyeo and Whachungchabyeo, of the waxy rice cultivars, were germinated at $27^{\circ}C$ for 3 days to compare the changes in some physico-chemical properties of the starch granules and the starch-hydrolysing enzyme activities during germination, respectively. With the starch granules, the amount of long glucose chains from amylose molecules were reduced in the non-waxy rices, while the chain length increased in the waxy rices. In the distribution profile of the glucose chain length from amylose molecules, we could observed that the chain length with DP (degree of polymerization) ranged 33 to 66 increased with the decreasing rate of the chain length with that above 130, regardless of the waxiness of rices. In addition, we observed that in contrast to a increase in chain length with DP ranged 14 to 33, the amount of short chains from A chain fraction decreased. Germination induced slight reduction in the polymerization rate of starch granules, and decrease in both initiation and termination temperatures for the gelatinization. ${\alpha}-Amylase$ activity of rices germinated for 3 days found to he higher than that of malt. Especially, the activity of Shinsunchalbyeo was revealed to be highest, about two fold higher than that of malt. In contrast, ${\beta}-amylase$ of the waxy rice found to be considerably less active than malt, although the waxy showed prevalent activity as compared to the non-waxy rices.

• The Korean Journal of Rheology
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• v.1 no.1
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• pp.54-62
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• 1989

준희박과 농축용액에서 약간의 유연성을 갖는 강성막대형 고분자의 회전확산계수와 zero shear rate 점도를 예측하기 위해 한정된 강성 사슬모델이 제시되었다. 본 연구에서는 이제시된 모델을 분자량 분포를 갖는 다분산계로 확장시켰다. 분자들의 분자량 분포 (MW/Mn) 와 분포 함수를 알수 없기 때문에 해당분자에 가장 적당한 분자량 분포와 함수를 취하였다. 만약 이것들을 알고 있다면 제시된 모델로 회전확산계수와 zero shear rate 점도 등과 같은 인자들을예측할수 있었다. 단분산계의 경우와 같이 다분산계에서도 회전확산계수 의 평균분자 윤곽길이 의존도는 L-7 에 비례하는 것으로 나타났다. Doi와 Edwards 의 튜브 모델에 의한 L-9 과 다른 이유는 분자들의 거동을 관찰하기 위해 임의로 선정된 하나의 막 대형 고분자운동을 제약하는 정도가 심하지 않았으며 따라서 제약 완화시간도 훨씬 짧았기 때문이다. 더구나 점도와 회전 확산계수와 단분산계에서는 정성적으로 일치한데 제약 완화 시간도 훨씬 짧았기 때문이다. 더구나 점도와 회전적인 일치를 나타내었다. 이 모델로 기준 으로 하여 분자들의 길이와 종류에 관계없이 하나의 master curve를 그릴수 있었다.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.673-679
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• 2011

Bimodal high-density polyethylenes with different comonomer type and content were synthesized by polymerization of ethylene using Ziegler-Natta catalyst. Their structure and properties were studied using GPC, NMR, DSC and tensile test. It was found that ethylene/1-hexene copolymer exhibits higher tensile strength and elongation at break than that of ethylene/1-butylene copolymer with similar comonomer content. The molecular weight decreases as the comonomer content of the polymer increases. Short chain branching affects the crystallinity and thus the morphology and consequently the mechanical properties of the corresponding bimodal high-density polyethylenes. After SSA treated, the multiple endothermic peaks were observed. Multiple endothermic peaks are mainly attributed to the heterogeneity of ethylene sequence length and lamellar thickness. The difference of broadness index indicates that SCB distribution of polyethylene containing higher comonomer content has improved uniformity.

• Journal of Ginseng Research
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• v.24 no.2
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• pp.53-57
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• 2000

Chlamydospores were isolated from hyphae of Cylindrocanon destmctans by homogenization and/or ultrasonic treatment. Rate of the isolated chlamydospores by the homogenization with glass tissue grinder were 9.8% of all total chlamydospores formed in the culture of C. destructans. The length of mycelial fragments after the homogenization was about 400㎛ They were, however, formed in clusters of the chlamydospores and the mycelia The rate of the isolated chlamydospores from additional ultrasonic treatment after the homogenization of the mycelia were 74.3%. The length of mycelial fragments with the ultrasonic treatment was about 20 fm and chlamydospores seemed to be isolated from the mycelial mats and dispersed evenly in the culture. The numbers of chlamydospore in a catena were 1 to 8 cells after the homogenization on potato dextrose agar (PDA). Meanwhile the numbers of them after added ultrasonic treatment were 1 to 4 cells. Germination percentages of the isolated chlamydospores from the ultrasonic treatment were 46.8% after incubation of 2 days on PDA at 20。C and 60.7% after incubation of 13 days at 5。C, respectively. Germination rate of chlamydospores to the total chlamydospores produced by the ultrasonic treatment was 55.8%. However, it was increased to 74% when it was measured in the germinated catenae to the total catenae.

• Elastomers and Composites
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• v.48 no.4
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• pp.269-275
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• 2013

In this study, we prepared poly(ethylene-ter-1-hexene-ter-divinylbenzene) using various metallocene catalysts with trityl tetrakis(pentafluorophenyl)borate/triisobutylaluminium cocatalysts system. We tried rac-$Et(Ind)_2ZrCl_2$, rac-$SiMe_2(Ind)_2ZrCl_2$, and rac-$SiMe_2(2-Me-Ind)_2ZrCl_2$ to choose optimum metallocene catalyst, comparing with catalytic activity, molecular weight, molecular weight distribution of the terpolymers. To study the effects of chain length of high ${\alpha}$-olefins on the terpolymerization, we synthesized the terpolymers using 1-hexene, 1-octene, 1-decene or 1-dodecene. We characterized chemical composition, thermal properties, and mechanical properties of the terpolymers.

• Applied Biological Chemistry
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• v.43 no.1
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• pp.18-23
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• 2000

stract : Fourteen varieties of glutinous rices were examined on amylopectin fine structure and physicochemical properties of starch granules. The amylopectin chain length distribution and short chain/long chain ratio were investigated by enzymatic treatments followed by high-performance size-exclusion chromatographic separation. Chain length distribution profiles of the isoamylase-debranched amylopectins showed distinct patterns according to varieties. Beongok showed the highest short chain/long chain ratio, while TP2579A1 showed the lowest one. Sharebyeo-152-1-B showed the highest hydrolysis rate to 15% $H_2SO_4$, while Sandong 47 showed the lowest one. Fourteen varieties of rice starch granules showed A-type pattern on X-ray diffractograms. Non-gelitinized starch granules from Keochang 1 and Beongok had almost 100% hydrolysed by glucoamylase for 3 hrs at $370^{\circ}C$.

• Polymer(Korea)
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• v.39 no.1
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• pp.165-168
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• 2015

Thermoresponsive polymers were successfully synthesized by a combination of atom transfer radical polymerization (ATRP) and Cu(I)-catalyzed 1,3-dipolar cycloaddition of azide and alkynes (click chemistry). Poly(2-hydroxyethyl methacrylate) (PHEMA) was synthesized by ATRP, followed by introduction of alkyne groups using pentynoic acid, leading to HEMA-alkyne. Homopolymers having secondary amine groups, tertiary amines with hydroxyethyl and hydroxypropyl groups were synthesized by adding 2-azido-N-ethyl-ethanamine, 2-[(2-azidoethyl)amino]ethanol, and 2-[(2-azidoethyl)amino]propanol, respectively, to the PHEMA-alkyne backbone using click chemistry. Molecular weight (MW), molecular weight distribution (MWD), and click reaction efficiency were determined by gel permeation chromatography (GPC) and $^1H$ NMR spectroscopy. The transmission spectra of the 1.0 wt% aqueous solutions of the resulting polymers at 650 nm were measured as a function of temperature. Results showed that the lower critical solution temperature (LCST) could be easily controlled by the length of the hydroxyalkyl groups.