• Macromolecular Research
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• 제15권5호
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• pp.430-436
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• 2007

The dinuclear half-sandwich CGCs (constrained geometry catalyst) with a polymethylene bridge, $[Ti({\eta}^5 : {\eta}^1-indenyl)SiMe_2NCMe_3]_2(CH_2)_n]$[n = 6 (1) and 12 (2)], have been employed in the copolymerization of ethylene and norbornene (NBE). To compare the mononuclear metallocene catalysts; $Ti({\eta}^5 : {\eta}^1-2-hexylindenyl)SiMe_2NCMe_3$ (3), $(Cp^* SiMe_2NCMe_3)$Ti (Dow CGC) (4) and ansa-$Et(Ind)_2ZrCI_2$ (5), were also studied for the copolymerization of ethylene and NBE. It was found that the activity increased in the order: 1 < 2 < 3 < 5 < 4, indicating that the presence of the bridge between two the CGC units contributed to depressing the polymerization activity of the CGCs. This result strongly suggests that the implication of steric disturbance due to the presence of the bridge may playa significant role in slowing the activity. Dinuclear CGCs have been found to be very efficient for the incorporation of NBE onto the polyethylene backbone. The NBE contents in the copolymers formed ranged from 10 to 42%, depending on the polymerization conditions. Strong chemical shifts were observed at ${\delta}$42.0 and 47.8 of the isotactic alternating NBE sequences, NENEN, in the copolymers with high NBE contents. In addition, a resonance at 47.1 ppm for the sequences of the isolated NBE, EENEE, was observed in the $^{13}C-NMR$ spectra of the copolymers with low NBE contents. The absence of signals for isotactic dyad at 48.1 and 49.1 ppm illustrated there were no isotactic or microblock (NBE-NBE) sequences in the copolymers. This result indicated that the dinuclear CGCs were effective for making randomly distributed ethylene-NBE copolymers.

• Carbon letters
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• 제25권
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• pp.89-94
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• 2018

In this study, we tried to prepare an isotropic spinnable pitch which can be useful to prepare the general purpose carbon fiber through the co-carbonization of biomass tar with ethylene bottom oil under two different preparation methods (atmospheric distillation, pressurized distillation). The results showed that the ethylene bottom oil added co-carbonization was very effective to decrease of the oxygen contents for obtaining a stable spinnable pitch. The pressurized distillation was more effective to reduce the oxygen functional groups of pitches than atmospheric distillation. The obtained spinnable pitch by the pressurized distillation showed higher pitch yield of 42% and lower oxygen content of 9.12% than the spinnable pitch by the atmospheric distillation. The carbon fiber derived from the pressurized distillation spinnable pitch by carbonization at $800^{\circ}C$ for 5 min showed that the higher tensile strength of carbon fiber was increased up to 800 MPa.

• 한국작물학회지
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• 제49권4호
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• pp.300-304
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• 2004

Gibberellic acid did not affect ethylene production, whereas gibberellin biosynthesis inhibitors triggered ethylene production in dormant tubers. Gibberellic acid did not induce sprouting of dormant tubers, however, treatment of gibberellin biosynthesis retardants enhanced sprouting rates. Sprouting rate in ancymidol-treated tubers was highest among gibberellin biosynthesis retardants. Sprouting rate of tubers treated with ancymidol increased to $91.4\%$. Batatasin-III content in $GA_3$ treated tuber was increased in the highest concentration $(30{\mu}g\;I^{-1})$. Tubers treated with mepiquat chloride, Batatasin-I was increased steadily, but contents of Batatasin-III and V showed dramatic decrease at the $ 1,000{\mu}g\;I^{-1})$ concentration. This infers that gibberellin biosynthesis retardants play key roles in promoting breaking dormancy on dormant tubers of Chinese yam.

• 폴리머
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• 제25권4호
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• pp.528-535
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• 2001

본 연구에서는 polyol, MDI, 실리콘 유화제, 물을 기본 폴리우레탄 조성으로 설정하였으며, 경질 폴리우레탄 폼에 있어서 sitff-chain 요소인 에틸렌 글리콜의 첨가에 의하여 가교밀도가 증가하며, 이에 따른 셀의 크기, 발포 배율, cream time, gel time, take free time의 변화, 최종 자유 발포체 높이, 반응 온도, 단열도 변화를 관찰하였다. 발포제는 시클로펜탄을 사용하여 경질 물리우레탄을 발포하였으며, 상온, 상압에서 hand mixing 으로 5000 rpm, 4sec의 범위 안에서 혼합시킨 뒤에, 에틸렌 글리콜의 양을 변화시켜 200 ${\times}$ 200 ${\times}$ 200 mm 내의 나무 금형 안에서 발포 실험하였다. 이소시아네이트 인덱스를 고정시켰을 경우 에틸렌글리콜의 양이 증가함에 따라 셀의 크기는 약 5.1%와 열전도는 약 14%가 감소하였다.

• 폴리머
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• 제33권2호
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• pp.137-143
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• 2009

이 연구에서 norfloxacin(NFX)이 담지된 poly($\varepsilon$-caprolactone)/poly(ethylene glycol)(PCL/PEG, abbreviated as CE) 이중블록공중합체로 구성된 고분자 미셀을 제조하였다. 입자크기는 PCL블록길이에 따라 60$\sim$200 nm사이였다. 임계회합농도는 소수성 PCL 블록길이가 증가함에 따라 감소하는 경향을 보였다. $^1H$-NMR 연구에서 PCL 블록은 내핵, PEG는 외피를 형성한 미셀구조로 형성되었음을 확인하였다. 약물의 방출은 약 2일간 지속되었으며 PCL블록길이와 약물함량이 증가함에 따라 감소하는 경향을 보였다. 항미생물 성능 실험에서 고분자 미셀은 기존의 NFX와 비슷한 독성을 보였다.

• 한국산업보건학회지
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• 제9권1호
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• pp.112-124
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• 1999

The purposes of this study were to provide the data for composition of ethylene glycol ethers and 2-ethoxyethyl acetate(EEA) exposure assessment of workers in various industrial operations. In this study, 80 thinners were analyzed to identify their composition and the air concentration of 2-ethoxyethyl acetate(EEA) and urinary 2-ethoxyacetic acid(EAA) were measured. In this study the subjects were the total of 183 drawn from 98 workers who were occupationally exposed to EEA and 85 workers who were not. The results were as follows: 1. There were found average 4.2 components in each thinner. 2. There were 90 components(26.9%) in ethylene glycol ethers of total of 334 detected organic solvents 3. Ethoxyethyl acetate, ethoxyethanol, buthoxyethanol, methoxy-ethanol were found in 30(37.5%), 27(33.8%), 19(23.8%), 2thinners(2.5%), respectively and their contents were average 18.5%. 4. Benzene was found 8 thinners(10.0%) of the total 80 surveyed. 5. In the electronic painting workers EEA exposure concentration was the highest, as showed 2.88ppm(0.01~15.1ppm), cases of exceeded threshold limit value(TLV=5ppm) were 7(10.6%) workers among the total of 98 exposed workers. 6. The geometric mean of urinary EEA in exposed workers was 1.61 mg/gcreatinine, and was higher than that of workers who were not exposed. In the electronic painting workers and offset printers, the geometric mean of urinary EAA was the highest showing 2.8 mg/gcreatinine. 7. The correlation coefficient between urinary concentration of EAA and air concentration of EEA was 0.90(P<0.05). The present results suggest that composition of ethylene glycol ethers in thinners must be evaluated when industrial hygiene surveys and biological monitoring are performed.

• 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.

• 생물환경조절학회지
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• 제19권3호
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• pp.159-164
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• 2010

염생식물 중 생체로 이용되고 있는 수송나물(Salsola komarovi Iljin)과 해홍나물(Suaeda maritima L. Dum.)의 상품화를 위해 포장 판매 및 저장이 동시에 가능한 MAP(modified atmosphere package)의 저장성을 몇가지 온도에서 비교하였다. 온실에서 재배한 수송나물과 해홍나물을 $50{\mu}m$(ceramic) 필름으로 포장하여 $2^{\circ}C$, $10^{\circ}C$, $25^{\circ}C$에 저장하였다. 저장중 생체중 감소는 모두 1% 미만이었는데, 역시 상온에서 가장 빠르게 감소하였으며, 수송에서 감소폭이 컸다. 포장재내 산소 농도는 저장온도별로는 $2^{\circ}C$에서 가장 높게 유지되었으며, $25^{\circ}C$에서는 수송이 해홍보다 낮은 농도를 보였다. 포장재내 이산화탄소 농도는 산소농도와 반대로 저장온도별로는 $25^{\circ}C$에서 가장 높았으며, 식물별로는 수송에서 높았는데 두 식물 모두 $2^{\circ}C$와 $5^{\circ}C$에서는 1% 이하로 유지되었다. 포장재내 에틸렌 농도는 $10^{\circ}C$에서 $2^{\circ}C$보다 높았으나, 통계적인 유의성은 없었다. $10^{\circ}C$에서 에틸렌 농도는 두 식물 모두 $20{\mu}L{\cdot}L^{-1}$으로 같은 수준으나, $2^{\circ}C$에서는 해홍이 다소 높았다. 온도에 따른 포장재내 이산화탄소와 에틸렌 농도는 저장온도가 높을수록 높았는데, 수송나물에서는 $2^{\circ}C$와 $10^{\circ}C$간 통계적 유의성이 있는 차이를 보인 반면, 해홍나물의 경우 그 차이에 통계적 유의성이 인정되지 않았다. 관능검사로 실시한 외관상 품질은 3점까지 상품성을 인정하였는데, 수송나물의 경우 상품성인 인정된 저장일수가 $24^{\circ}C$에서는 3일, $10^{\circ}C$에서는 7.5일 $2^{\circ}C$에서는 14일이었고, 해홍나물은 $24^{\circ}C$에서는 3.5일, $10^{\circ}C$에서는 9.5일 $2^{\circ}C$에서는 11일이었다. 외관상 품질 변화와 포장재내 이산화탄소와 에틸렌 농도로 볼 때 해홍나물의 경우 $2^{\circ}C$의 저온에서 저장성이 $10^{\circ}C$와 차이가 없어 저온장해가 의심되었다.

• 생물환경조절학회지
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• 제9권1호
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• pp.40-46
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• 2000

본 실험은 Japanese mint의 생체저장에 있어 저장온도와 필름종류의 영향을 비교하여 적정 저장조건을 제시하고자 실시하였다. 생체중 감소로 볼 때 Japanese mint는 다소 두꺼운 40$\mu$m 이상의 필름이 효과적이었다. 저장 중 필름내 가스농도는 필름이 두꺼운 CE 80(ceramic 80$\mu$m 필름)이 CE 40(ceramic 80$\mu$m 필름)보다 높았으며 저장온도별로는 3$^{\circ}C$이하에서는 저온장해가 발생하여 온도별 차이가 없거나 오히려 1$^{\circ}C$에서 가장 높은 가스농도를 보였다. 저장 중 엽록소 함량감소는 5%이상의 수분손실과 0.5ppm이상의 에틸렌에 의해 촉진되었으나, 4%이상의 이산화탄소농도에서는 그 감소는 억제되었다. 저장수명은 3$^{\circ}C$저장에서 30일로 다른 저장온도의 두배였다. 가장 저장수명이 길었던 3$^{\circ}C$에서 저장 최종일에 외관상품질은 CE 40에서 가장 좋았으며 저온장해 정도를 나타내는 이온용출량도 가장 낮게 나타났다. 이상의 결과로 볼 때 Japanese runt 저장시 적정 저장온도는 3$^{\circ}C$이며, MA저장시 포장재로는 ceramic 40$\mu$m 필름이 적절하였다.