• Bulletin of the Korean Chemical Society
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• 제6권2호
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• pp.68-73
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• 1985

Normal modes of solids HF, HCl and polyethylene having the exciting spectrometric phenomena have been evaluated by taking the lowest temperature phase of these species in the solid. The solids HF and HCl have the same space group as C$_{2}{\nu}$, and polyethylene has a space group with D$_{2h}$. The normal modes were obtained by the valence force field with modified force constants and a quantitative description of the normal mode is adjusted by the potential energy distribution (PED). From the PED, the most fittable force constants are also obtained. We have intended to calculate the normal modes by using the smallest size of the model and the simple computational process. To remove the edge effects being occurred in constructing the single cluster model, different from the boundary condition being generally used up to now, the idea of pseudolattice method being successfully applied to MO calculations of solid was extended to normal mode analysis in order to give the same environment for all moecules in a chosen cluster. By using the above valence force field and boundary condition, we obtain the assigned frequencies and compare those results with the results obtained by others.

• 한국식품영양과학회지
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• 제27권6호
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• pp.1137-1142
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• 1998

Modified atmosphere packagings were designed by combining the respiration characteristics of the enoki mushroom at 10oC and the measured film permeabilities to O2 and CO2 gases to attain the beneficial package atmosphere were fabricated and tested during storage. The packages of 100g size with 30 m low density polyethylene and cast polypropylene showed the good agreement between estimated and experimental package atmospheres. However, polyvinylchloride stretch wrap packs showed the gas composition close to the air, which was due to leaking of stretch wrapping. The CPP package attaining O2 below 1% and CO2 concentration of 15~20% gave the best retention of quality and thus the longest shelf life among the tried packages, and it was superior to the others in the Hunter L value, stipe elongation and sensory qualties.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1990년도 추계학술대회
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• pp.61-63
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• 1990

To develop better blood compatibility of commercial polyurethane(PU), PU surface was chemically modified wi th a hydrophobic perfluorocarhon or a hydrophilic polyethylene oxide(PEO) and/or sulfonated groups, respectively. The water contact angle of modified PUs varied from $110^{\circ}$ to $0^{\circ}$. All the modified PUs were more blood compatible than untreated PU. In particular, PEO-sulfonate grafted PUs showed a very enhanced antithrombogenicity due to the synergistic effect of PEO and $SO_3$ groups. Therefore more hydrophobic and hydrophilic PU surfaces are promising for improving the blood compatibility.

• Elastomers and Composites
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• 제32권3호
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• pp.166-172
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• 1997

The objective in this study was investigated temperature susceptibility and low temperature fracture of rubber modified asphalt. A chlorinated polyethylene elastomer, Tyrin CM0730, was added to 200/300 grade asphalt with 3.0 and 5.0wt% to improve campatibility. The elastomer modified asphalts were analyzed for temperature susceptibility relating to penetration index(PI) and penetration-viscosity number(PVN) as well as low temperature fracture relating to fracture energy $(G_{IC})$. These indices were obtained from the measurements of penetration, viscosity, failure load and modulus. The addition of small amounts of elastomer to the asphalt resulted in a significant increase of both the PI and PVN over an unmodified asphalt. Also, the fracture energy increased with the addition of elastomer to asphalt. These significant improvement at both the high and low temperature result in enhanced performance.

• 한국의류학회지
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• 제20권6호
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• pp.992-1001
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• 1996

The binding of polyethylene glycol (PEG, average molecular weight 600) to cotton fabrics was achieved by using pad-dry-cure process in the presence of citric acid, MgCl3·6H3O, DMDHEU, and TEAHCL. Treated fabrics were dyed with direct, acid, and basic dye. Wrinkle recovery angles, durable press rate, wettability, dyeability and color fastness to washing of all treated cottons were evaluated. The results of this study were as follows: 1. The wrinkle resistance of the PEG treated cottons was increased by increasing PEG and DMDHEU concentration. 2. The wettability of the PEG treated cottons was decreased by increasing PEG and DMDHEU concentration, increased by increasing TEAHCL concentration. 3. PEG/DMDHEU/TEAHCL treated cottons had greater affinity on direct, acid, and basic dye than untreated cottons, and dyeability of the modified cottons was improved compare to untreated fabrics. 4. Color fastness to washing of the PEG/DMDHEU/TEAHCL treated cottons was good except for the wash fastness of the direct dye.

• Journal of Pharmaceutical Investigation
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• 제21권3호
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• pp.143-147
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• 1991

${\alpha}-amylase$ was immobilized on the surface of polyethylene glycol(M.W. 2000) grafted polyurethane film using diisocyanate in an attemp to develop enzyme immobilized polymeric materials. The surface morphology of the modified polyurethane film was examined by SEM. Effects of pH and temperature on the activity of the immobilized ${\alpha}-amylase$ were investigated. The optimal pH range of the activity was $7.0{\sim}7.5.$ The immobilized ${\alpha}-amylase$ demonstrated high thermal stability and maintained consistent activity during long-term storage.

• Journal of Pharmaceutical Investigation
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• 제25권2호
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• pp.145-152
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• 1995

The superoxide dismutase (SOD) mimetic activity of copper complex of 3,5-disopropylsalicylic acid (Cu(II)-DIPS) was tested and compared to those of human recombinant SOD (hrSOD) and its conjugate form with polyethyleneglycol (PEG) using fer- ricytochrome c reduction assay. Stability constant of Cu(II)-DIPS was measured po- tentiometrically using SCOGS2 program. In the presence of 10 g/L albumin, Cu(II)-DIPS lost most of its SOD mimetic activity. HrSOD was modified with polyethylene glycol (PEG) of M.W. 5000. These conjugates have markedly prolonged plasma half-lives of enzymatic activity (15.5 hr) compared to native hrSOD (5 min). In summary, efficient SOD mimetics should be stable enough not to dissociate in blood by serum protein. HrSOD could have longer half-life by conjugation with inert PEG for sustained SOD effect.

• 대한의용생체공학회:의공학회지
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• 제10권3호
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• pp.237-242
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• 1989

The physical properties and drug release behaviours of polyethylene glycol grafted poly ${\gamma}$- benzyl L-glutamate (PEG- g- PBLG), polyethylene glycol crosslinked poly ${\gamma}$-benzyl L- glutamate(PEG-c-PBLG), and PBLG homopolymer are compared. PBLG containing PEG segements showed higher wettability and larger enlongation than PBLG homoplymer, but lower elastic modulus. The release rate of rhodamine is strongly influenced by the wettability of the polymer. Rhodamine is more rapidly released from PEG-c-PBLG membrane having a larger water contact angle than from other polymer having a lower water contact angle. The surfaces of PBLG derivative membranes are modified by substitution reaction using hydroxyalkylamine. The resulting polymer membranes showed hider wettability and swelling ratio than virgin membranes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.219-222
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• 1998

The space charge and conduction characteristics of chemically modified vinylpyridine (VP) grafted low density polyethylene (LDPE) was investigated. VP grafted LDPE was analyzed by elemental analysis (EA) to confirm the grafting reaction. Homocharge was developed in VP grafted LDPE at low graft ratios and changed to heterocharge with increasing the content of VP. In conduction experiment, current densities of VP grafted LDPE were lower than that of LDPE and VP grafted LDPEs showed almost the same conduction characteristics as vinylpyridine graft ratio increased

• Macromolecular Research
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• 제10권5호
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• pp.282-285
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• 2002

In this paper, we report a modified technique for the production of oriented continuous nanofibers instead of non-woven mats using a rapidly rotating collection device. We are interested in retaining physical properties such as electrical conductivity of fiber bundles in their axial direction. The experiments were performed using polyethylene oxide (PEO) and its blend with polyaniline (PANI). According to the results, a typical fiber with a uniform diameter of about 100 nanometer was produced. The fibers from the PEO/ CHCl$_3$ solution show high crystallinity and good orientation whereas the fibers from the blend solution of PEO/PANI/m-cresol and CHCl$_3$ show no preferred orientation. However, the fibers of the blend exhibit high electrical conductivity of 33 S/cm for a fiber bundle at a PANI level of 50 %.