• 대한의용생체공학회:의공학회지
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• 제16권1호
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• pp.9-16
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• 1995

Biodegradable poly (I ,4-butanediol succinate) (PBS) was synthesized from 1,4-butanediol and succinic anhydride. The glass transition temperature of poly (I, 4-butanediol succinate) was revealed at $73^{\circ}C$. The crystallization and cold crystallization of the polymers were investigated as a function of holding time in melt state, cooling rate. reheating, and molecular weight. Chain scission and/or cmsslinking did not occur in the melt state at var.ious holding times. Slower scanning rate can allow more times for nucleation, rearrangement, and packing of the polymer chain, so the onset temperature of crystallization from the melt was increased. PBS crystallized from the melt was found to have spherulitic structure. The degradation behavior of PBS was studied under basic conditions and with microorganisms using the modified ASTM method. In the basic solution. PBS lost up to 85% of its mass within two days. Based upon visual observation, the crystalline structure of films composed of larger molecular weight polymers retained their crystallinity longer than similar structures in low molecular weight samples.

• Journal of Microbiology
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• 제45권1호
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• pp.58-63
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• 2007

In this study, the relative synonymous codon and amino acid usage biases of the broad-host range phage, KVP40, were investigated in an attempt to understand the structure and function of its proteins/protein-coding genes, as well as the role of its tRNAs. Synonymous codons in KVP40 were determined to be AT-rich at the third codon positions, and their variations are dictated principally by both mutational bias and translational selection. Further analysis revealed that the RSCU of KVP40 is distinct from that of its Vibrio hosts, V. cholerae and V. parahaemolyticus. Interestingly, the expression of the putative highly expressed genes of KVP40 appear to be preferentially influenced by the abundant host tRNA species, whereas the tRNAs expressed by KVP40 may be required for the efficient synthesis of all its proteins in a diverse array of hosts. The data generated in this study also revealed that KVP40 proteins are rich in low molecular weight amino acid residues, and that these variations are influenced primarily by hydropathy, mean molecular weight, aromaticity, and cysteine content.

• 한국식품영양과학회지
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• 제24권5호
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• pp.651-657
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• 1995

모유성분을 고분자분획(20KD 이상 분자)과 저분자분획(20KD 이하 분자)으로 나누어 항산화력을 검토한 결과, 고분자분획이 저분자분획 보다 더 강력한 항산화력을 나타내었다. 이 모유의 항산화력은 주로 20KD 이상에 존재하는 항산화 효소에 기인할 가능성이 시사되어 모유의 채유 기간에 따른 항산화 효소를 비롯하여 protein-SH와 nonprotein-SH를 검토한 결과, catatase는 7일째 현저히 저하한데 비해 GSH peroxidase, GSH S-transferase는 7일째를 전후로 현저히 증가한 후 감소하는 경향을 나타내었다. Protein-SH는 채유 기간에 따라 차츰 감소하였으나 nonprotein-SH는 20일째 peak를 이루고 그 후 감소하였다. 이상의 결과로 부터 모유의 고분자분획은 강력한 항산화력을 나타내었으며, 이 항산화력은 catalase, GSH peroxidase 및 GSH S-transferase 등의 항산화 효소 활성에 기인할 것으로 사료된다.

• Macromolecular Research
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• 제12권1호
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• pp.112-118
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• 2004

With the goal of enhancing the creep resistance of ultra-high molecular weight polyethylene (UHMWPE), we performed gamma irradiation and post-irradiation annealing at a low temperature, and investigated the crystalline structures and mechanical properties of the samples. Electron spin resonance spectra reveal that most of the residual radicals are stabilized by annealing at 100$^{\circ}C$ for 72 h under vacuum. Both the melting temperature and crystallinity increase after increasing the dose and by post-irradiation annealing. When irradiated with the same dose, the quenched sample having a higher amorphous fraction exhibits a lower swell ratio than does the slow-cooled sample. The measured tensile properties correlate well to the crystalline structure of the irradiated and annealed samples. For enhancing creep resistance, high crystallinity appears to be more critical than a high degree of crosslinking.

• 한국인쇄학회지
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• 제29권1호
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• pp.45-59
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• 2011

According as gradually increasing the demand for Eco-friendly products it has been progressed fairly development at a field of printing and printing inks. The Inks are used by soy oil beginning of ink industry for preventing environment. Now it is possible to make Eco-friendly inks with vegetable ester. So it is not necessary to use petroleum-based solvents for preventing environment. But There is some problems if using vegetable ester to inks. Vegetable ester has high solubility, it causes misting and low viscosity of the Inks. So resin is required high performance. Thus, in this paper, I studied about the properties variation of the Varnish and inks According to using the phenolic modified rosin ester and Soy oil Methyl esters. The compared in order of average molecular weight by the GPC method, rheological properties were found by rotational rheometer, and emulsion behavior were compared by high speed emulsification tester.

• Food Science and Biotechnology
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• 제17권4호
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• pp.755-760
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• 2008

The aim of this study was to produce resistant starch preparations from acid-modified com starches prepared at various hydrolysis levels (0.5-4.0 hr). Effect of autoclaving cycles on resistant starch (RS) formation was investigated. Molecular weight distribution, pasting and functional properties of acid-modified com starches were determined. For RS formation native and acid-modified starch samples were gelatinized and autoclaved (1 or 2 cycles). While native and acid-modified starches did not contain any RS, the levels increased to 9.0-13.5% as a result of storage at $95^{\circ}C$ after first autoclaving cycle. Second autoclaving cycle together with storage at $95^{\circ}C$ brought final RS contents of the samples incubated at 4 and $95^{\circ}C$ after the first cycle to comparable level. As acid modification level increased, the amount of high molecular weight fractions decreased, resulting in significant decreases in viscosities (p<0.05). The samples produced in this study had low emulsion stability and capacity values.

• 한국수산과학회지
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• 제32권5호
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• pp.607-611
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• 1999

초음파를 이용하여 저분자 $\lambda$-carrageenan을 제조한 다음 그 특성을 조사한 결과 가용한계농도에 있어서는 대조구 $\lambda$-carrageenan는 $3\%$에서 가용한계농도를 나타내었고, 초음파 처리에 의해 저분자화가 많이 될수록 가용한계농도는 더 높게 나타났다. 알콜 침전도는 대조구에 비해 초음파 처리구가 낮게 나타났다. 유화능은 대조구에 비하여 처리구가 낮게 나타났으며, 분자량이 낮을 수록 유화능은 낮게 나타났다. 점도는 예상하였던 대로 초음파 처리에 의해 저분자화된 $\lambda$-carrageenan (P-1, P-2)이 대조구에 비해 낮았으며, 초음파 처리가 많이 될수록 점도는 낮게 나타났다. $\lambda$-carrageenan이 갈변반응에 대하여 크지는 않으나 어느 정도 갈변억제효과를 가지고 있는 것으로 나타났으며, 저분자화가 많이 될수록 갈변억제효과는 전반적으로 떨어지는 것으로 나타났다. 전기영동을 이용하여 $\lambda$-carrageenan 및 저분자화된 $\lambda$-carrageenan의 분자량을 조사한 결과 대조구 $\lambda$-carrageenan의 분자량은 약 250,000이었으며 초음파 처리에 따른 저분자화 된 $\lambda$-cariageenan의 분자량은 각각 184,000(P-1) 및 67,000 (P-2)정도 이었으며, GPC 결과도 이와 비슷하였다.

• Fibers and Polymers
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• 제6권1호
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• pp.13-18
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• 2005

PLA/LPCL/HPCL blend fibers composed of poly (lactic acid) (PLA), low molecular weight poly ($\varepsilon$-caprolactone) (LPCL), and high molecular weight poly ($\varepsilon$-caprolactone) (HPCL) were prepared by melt blending and spinning for bioab­sorbable filament sutures. The effects of blending time and blend composition on the X-ray diffraction patterns and tensile properties of PLA/LPCL/HPCL blend fibers were characterized by WAXD and UTM. In addition, the effect of in vitro degra­dation on the weight loss and tensile properties of the blend fibers hydrolyzed during immersion in a phosphate buffer solu­tion at pH 7.4 and 37$^{\circ}C$ for 1-8 weeks was investigated. The peak intensities of PLA/LPCL/HPCL blend fibers in X-ray diffraction patterns decreased with an increase of blending time and LPCL contents in the blend fibers. The weight loss of PLA/LPCL/HPCL blend fibers increased with an increase of blending time, LPCL contents, and hydrolysis time while the tensile strength and modulus of the blend fibers decreased. The tensile strength and modulus of the blend fibers were also found to be increased with an increase of HPCL contents in the blend fibers. The optimum conditions to prepare PLA/LPCL/HPCL blend fibers for bioabsorbable sutures are LPCL contents of $5 wt\%, HPCL contents of $35 wt\%, and blending time of 30 min. The strength retention of the PLA/LPCL/HPCL blend fiber prepared under optimum conditions was about $93.5\% even at hydrolysis time of 2 weeks.

• 한국식품과학회지
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• 제27권6호
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• pp.860-865
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• 1995

처리 방법을 달리한 메밀(날메밀, 볶은메밀, 찐메밀)에서 효소적 방법으로 비소화성 다당과 가용성 다당을 분리하였다. 가용성 다당은 저분자 가용성 다당과 고분자 가용성 다당으로 비소화성 다당은 crude hemicellulose(CH)와 alcohol insoluble hemicellulose(AIH), residue 그리고 저분자 불용성 다당으로 각각 분리하였다. 다당의 함량은 조리방법에 따라 차이를 나타냈으며 가용성 다당 중 고분자 가용성 다당의 함량은 $5.5{\sim}9.4%$였으며, 저분자 가용성 다당의 함량은 $75.9{\sim}84.2%$였다. 비소화성 다당 중 CH는 $3.2{\sim}9.6%$, AIH는 $0.9{\sim}1.7%$, residue는 $2.0{\sim}2.4%$, 저분자 불용성 다당은 $0.8{\sim}4.2%$였다. 가용성 다당에서는 유리당이 검출되었으나 비소화성 다당에서는 유리당이 검출되지 않았으며 모든 다당 분획에서 단백질이 검출되었다. 가용성 다당의 주요 성분당은 glucose였으며, 비소화성 다당에서는 glucose 이외에 rhamnose, arabinose, xylose, galactose, mannose가 확인되었다.

• 폴리머
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• 제39권3호
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• pp.514-521
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• 2015

본 연구는 자동차, 건축, 디스플레이 부품 접합 등에 사용되는 다층구조형 양면 점착테이프에 대한 것으로 UV 경화에 의해 제조된 아크릴폼 기재에 용제 건조형 점착제(AD)를 양면에 붙이고 피착제 종류에 따른 박리강도와 전단접착강도를 고찰하였다. AD 종류와 기재 조성에 따른 접착력 변화 및 피착재로 사용한 플라스틱에 대한 접착력을 고찰한 결과, AD의 분자량(MW)이 증가할수록 박리강도 및 전단접착강도가 증가하였으나 약 65만 이상의 MW를 가진 AD는 접착력이 감소하는 거동을 보였다. 양면 점착테이프에 사용된 AD층 두께가 얇을수록 온도감소와 함께 높은 물성 값을 보였다. 기재와 AD와의 계면접합 특성은 MW 615000(AD-4)을 사용한 것이 가장 우수하였으며, MW가 615000보다 낮으면 기재인 아크릴 폼과의 계면이 분리되는 결과를 보였다. 따라서 본 연구에서 검토한 다층구조형 양면 점착테이프는 표면에너지가 낮은 플라스틱 부품 및 곡면 부위에 적용가능한 산업분야에 유용하게 사용될 수 있을 것으로 판단된다.