• Korean Chemical Engineering Research
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• 제50권1호
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• pp.88-92
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• 2012

초임계 메탄올에서 가교폴리프로필렌의 탈가교 반응에 대해 연구하고 이를 가교폴리에틸렌의 탈가교 반응과 비교하였다. 회분식 반응기를 이용하여 반응 온도와 초기 겔 함량이 탈가교 반응 속도에 미치는 영향을 알아보았고, 정량적 분석을 위해 반응 전후의 겔 함량을 측정하였다. 반응 온도가 증가할수록, 초기 겔 함량이 증가할수록 탈가교 반응속도가 증가하였고, 반응 속도는 겔 함량에 선형적으로 의존하였다. 가교폴리프로필렌의 탈가교 반응이 가교폴리에틸렌보다 빠르게 일어나는 것을 확인하였고, 반응속도상수를 계산하여 이를 정량적으로 확인하였다. 이를 통해 재활용 측면에서는 가교폴리프로필렌이 가교폴리에틸렌보다 우수한 것을 알 수 있다.

• 한국환경과학회지
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• 제17권2호
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• pp.225-232
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• 2008

The objectives of this study were conducted to determine the effects of two chemical amendments on volatile fatty acids (VFA) and nitrogen contents in poultry litter after broiler chicks were raised in poultry houses for 6 weeks. Two different additives were applied as a top dressing to the litter at a rate of $AlCl_3{\cdot}6H_2O$ (200 g)+$CaCO_3$ (50 g) or Alum (200 g)+$CaCO_3$ (50 g)/kg of rice bran; untreated litter served as controls. Application of $AlCl_3+CaCO_3$ and Alum+$CaCO_3$ reduced total VFA contents by 67% and 51% at 6 weeks, respectively, compard to the control groups. The decrease in litter pH with two chemical treatments results in decreased proportion of VFA and increased nitrogen contents of the litter. These results indicate that treating $AlCl_3+CaCO_3$ and Alum+$CaCO_3$ to poultry litter offers the potential for reducing an environmental impact.

• 한국식품영양학회지
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• 제9권3호
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• pp.314-318
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• 1996

The purpore of this study was to elucidate the nutritional significance of the fruit-vegetable mixed juice during storage and distribution by examining the chemical composition of the mixed Juice for storage. The fruit-vegetable mixed Juices were sueriliged at 95$^{\circ}C$ for 30, 70, 100 seconds and the results of the changes in vitamin C contents, colors, total carotenoid contents, total aerobic counts and sensory evaluation of the mixed Juice were as follows: Vitamin C contents were drastically decreased at 7 day's storage and were not significantly different between the mixed Juices at p< 0.05 level after 7 day's storage. The longer the sterilization time and storage period of the mixed Juice was the higher changes in color was. The color changes in the sterilized samples were higher in order of 100, 70 and 30 seconds. Total carotenoid contents were slightly decreased according to storage period but were not affected by sterilization time. Total aerobic counts were 1.1 $\times$ 101 cfu/ml before sterilization, but it was negative after sterilization at 95t regardless of sterilization time. Sensory qualities such as color, flavor, taste and total acceptability of the mixed juice tended to be decreased by the Increased storage period and sterilization time. Especially, the sterilized sample for 100 seconds showed lots of changes In color.

• 폴리머
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• 제34권1호
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• pp.58-62
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• 2010

전분을 매트릭스 고분자로 하여 아크릴 단량체를 유화중합 방법으로 그래프트 중합하였다. 에멀젼의 점도와 입자경은 전분 함량이 증가함에 따라 전분의 히드록시기가 물과 상호작용하고 고분자 입자가 분산매인 물 쪽으로 팽윤함으로 인해 증가하였다. 에멀젼의 화학적 안정성은 전분 함량이 증가할수록 양호하였으나 내수성과 내알칼리성은 전분 함량이 증가할수록 친수성이 증가하면서 감소하였다. 탄산칼슘을 포함한 전분-아크릴 에멀젼 배합물의 불투명도는 전분의 함광이 증가함에 따라 전분 고유의 색깔에 의해 감소하였고 도막의 상태는 전분의 함량이 증가함에 따라 도막의 무정형 상태가 증가하면서 균열이 없는 매끈한 외관을 나타내었다.

• 한국가금학회지
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• 제25권2호
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• pp.55-64
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• 1998

This study was carried out to investigate the postmortem changes in physico-chemical characteristics of chicken meat with different breeds. Thigh and breast meats from Korean Native Chicken(KNC, 15-wk old), Wangchoo(15-wk old), and broiler(7-wk old) were stored at 5 ˚C. Differences in postmortem pH changes were not recognized among breeds, and pH showed by the lowest value at the 1st day of postmortem in all breeds. Breast meat had tendency to drop pH faster than thigh meat. Heme pigment contents showed no differences among breeds. KNC showed the lowest cholesterol contents in all breeds, total collagen contents showed the lowest value at the 1st day of postmortem, and thereafter it was gradually increased. Heat soluble collagen contents was lowest in Wangchoo. Water soluble and salt soluble protein showed the lowest extractability at the 1st day of storage. Broiler showed the highest extractability of these proteins and Wangchoo showed the lowest. Water holding capacity(WHC) had increasing tendency whilst cooking loss had decreasing tendency by the ageing. WHC of breast and thigh meat showed the highest values in KNC and broiler, respectively. Myofibrillar fragmentation index (MFI) was significantly increased in all breeds by the ageing. Breast and thigh meat showed almost same MFI in KNC and broiler, and in KNC and Wangchoo, respectively. Hardness of breast meat showed decreasing tendency by the ageing.

• 한국식품과학회지
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• 제9권1호
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• pp.10-12
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• 1977

제차(製茶)의 품질에 관계되는 차엽(茶葉)의 화학 성분을 보성 및 광주지방의 차수(茶樹)에서 5월, 7월 및 8월에 각각 채취하여 분석한 결과는 다음과 같다. 총질소 및 ascorbic acid는 두지방 시료 모두 일번차(一番茶), 이번차(二番茶) 및 삼번차(三番茶) 순으로 감소하는 경향을 보였으나 조섬유 및 tannin은 반대로 증가하는 경향을 보였다. 환원당, caffeine 및 회분의 함량은 차엽(茶葉)의 채취 시기에 따라 별다른 변화를 보이지 않았다. 그러나 가용성 회분의 alkalinity는 증가한 반면에 불용성 회분의 alkalinity는 감소의 경향을 보였다. 차엽(茶葉)중의 아미노산 조성은 glutamic acid를 비롯하여 16종이 함유되어 있는바 이들은 채취 시기가 늦을 수록 감소하는 경향을 보였다.

• Elastomers and Composites
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• 제30권3호
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• pp.195-206
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• 1995

To modify the NBR rubber roll which has poor abrasion and chemical resistance, NBR/PVC blends were prepared in various composition ratios. First of all, their miscibility and vulcanization characteristics were investigated. Their abrasion and chemical resistant properties and physical properties were also studied. DSC thermograms for NBR/PVC blends show only one Tg in the entire composition range, demonstrating a perfect miscibility. In the vulcanization characteristics tested by rheometer, maximum torque decreases as PVC contents increased. In the investigation of physical properties of NBR/PVC blends, hardness increases and elongation decreases along with the increasing contents of PVC. On the other hands, tensile strength increases with the increasing contents of PVC up to 11.1 wt. %, and then decreases with higher contents of PVC. While the abrasion resistance of NBR/PVC blends was similar to that of NBR itself, the chemical resistance of NBR/PVC blends was superior to that of NBR.

• Macromolecular Research
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• 제8권1호
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• pp.34-43
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• 2000

The melt rheology of four binary blends of ethylene 1-octene copolymers (EOCs) which consist of one component by Ziegler-Natta and another by metallocene catalysts, was studied to elucidate miscibility in the melt by using torsion rheometer at 200$\^{C}$ and different shear rates. The four blend systems, designated into the FA+FM, SF+FM, RF+EN, and RF+PL blend, are divided and interpreted based on the melt index (MI), the density and the comonomer contents. The melt viscosity such asη', η", and η$\^$*/ is weight average value if the comonomer contents are similar, otherwise they show different manner. The experimental resole are analyzed based on the Cole-Cole plot of logη' uersus log η", the logarithmic plots of the dynamic storage modulus (G') versus the dynamic loss modulus (G") for various blend compositions, and the melt viscosity of 11', n", and f" as a function of blend compositions. As a cerise-quence, the FA+FM blend is miscible, but the SF+FM, RF+EN, and RF+PL blends are not in the melt. Thus miscibility of the blends studied in this communication is suggested to strongly influence by the comonomer contents rather than the density or the MI.

• 한국환경과학회지
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• 제16권8호
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• pp.891-896
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• 2007

Waterborne polyurethane dispersions (WPUD) were prepared by poly(ethylene glycol) adipate as the polyester type, ${\alpha},{\omega}-hydroxyalkyl$ terminated polydimethylsiloxane (PDMS-diol) as the polysiloxane type, hexamethylene diisocyanate, and isophorone diisocyanate, dimethylol propionic acid. The effects of PDMS-diol contents on the particle size, thermal and surface properties of WPUD were investigated. The structures of the synthesized WPUD were confirmed using by FT-IR. The surface, thermal and mechanical properties were investigated by measuring the contact angles, DSC, TGA and UTM. As PDMS-diol contents increased, the particle size, the contact angle, and the elongation was increased, while the tensile strength was decreased. Also the thermal stabilities of the synthesised WPUD were increased as PDMS-diol contents increased.

• 한국토양비료학회지
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• 제33권6호
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• pp.393-397
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• 2000

퇴비의 시용량에 따른 사과의 수량과 토양화학성에 미치는 영향을 조사한 결과는 다음과 같았다. 사과원에 퇴비시용량의 증가에 의해 토양중의 인산함량 및 치환성 양이온의 함량이 증가하였으나, 유기물은 거의 변화가 없었다. 퇴비의 시용량이 증가할수록 사과의 수량은 증가하였으나, 경도 및 당도의 차이는 없었다. 화학비료를 감비처리하고 퇴비의 시용량을 높인 결과 퇴비의 시용량이 증가함에 따라 토양 중 유기물 및 Ca의 함량은 증가하였다.