• Korean Journal of Microbiology
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• v.23 no.3
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• pp.190-196
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• 1985

For frequency improvement of protoplast fusion in Brevibacterium flavum, Brevibacterium lactofermentum lactofermentum and Corynebacterium glutamicum, the effect of plasma expanders on fusion and cell wall regeneration, compatison between direct and two-step selection method, tendency of fusion frequency according to pH of fusion fluid and polyethylene glycol concentration were examined. By addition of 3% polyvinyl pyrrolidone to cell wall regeneration medium, regeneration frequencies were expressed 23 (Brevibacterium lactofermentum), 10.4 (Brevibacterium flavum) and 2.7 (Corynebacterium glutamicum) times higher than those of none polyvinyl pyrrolidone medium respectively.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.560-565
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• 2007

Copper fine particles, ranging from $0.11{\mu}m$ to $0.64{\mu}m$ in average size, were prepared by a chemical reduction method using hydrazine ($N_2H_4$) as a reduction agent in waste copper solutions. The effect of the amount of hydrazine addition was investigated on the properties of the obtained powders. Also, the effect of the addition of dispersing agents [Polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP)] during particle synthesis was studied. The powders, obtained from 1 M waste copper solutions, showed the mixtures of Cu and $Cu_2O$ crystals at low hydrazine addition amounts of 0.8 mol and 1.0 mol, while those exhibited pure Cu crystals at adequate hydrazine addition amount of 0.12 mol. The average size of the Cu powders decreased with increasing the concentrations of hydrazine and dispersing agents. The addition of PVA to the solutions as a dispersing agent was more effective than that of PVP in preventing the aggregation of particles.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.2
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• pp.155-162
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• 2004

Different adhesives(CF-clear, arabic gum, cethylmethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxy propyl cellulose, methyl cellulose) and particulate matters(bentonite, kaolin, calcium carbonate, peatmoss, talcum, vermiculite, zeolite, calcium hydroxide, plaster, calcium phosphate, vermiculite + calcium carbonate, vermiculite + kaolin, vermiculite + talcum) were evaluated by coating index method. According to the weight of single coated seeds, CF-clear and polyvinyl alcohol appeared to be the best coating adhesives for red clover and tall fescue seeds. Both vermiculite and vermiculite + talc(l : 1) for red clover, and vermiculite + talc(l : 1) for tall fescue appeared to be the best particulate matter(P < 0.01). Percent friability showed excellent results for the arabic gum, CF-clear, and polyvinyl alcohol when compared to others(p < 0.01). The coating index showed high with vermiculite and vermiculite + talc(l : 1) in coating red clover seed, and talc, vermiculite, and vermiculite + talc showed good coating index in coating tall fescue seed.

• Journal of Life Science
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• v.12 no.6
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• pp.721-730
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• 2002

This study was carried out to select new pelleting binder and material for Welsh onion seeds. The optimum treatments of the various plant growth regulators to improve seed germination of the Welsh onion was also estimated. There were no significant effects of growth regulators on the germination percentage, but germination was faster according to the number of days to 50% of the final germination ($T_{50}$) and the mean number of days to germination (MDG) than those of the control. Germinability was increased when the seeds were soaked in gibberellic acid ($GA_3$) solution for 24hrs, even though there was no synergy effect on the germinability when $GA_3$ was mixed with 6-benzylaminopurine (BAP). The optimum treatment for improving germination of Welsh onion was observed when the tested seeds was soaked in 500 $\mu$M of $GA_3$ at $20^{\circ}C$ for 24hrs. Also, when the seeds soaked in the aforementioned treatment, the rate of germination was increased at lower temperature than at $20^{\circ}C$, the optimal temperature. The percentage and the speed of seed germination depended on the kinds of pelleting binder and their concentration. It showed that the higher the concentration of the binder for seeds pelleting, the lower the percentage of seed germination. Among the pelleting binder, polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) were the best binders for seed pelleting, because seed germination using those binder did not affect on the concentration of binder. On the other hand, Carboxymethy cellulose (CMC) and methyl cellulose (MC) severely inhibited the seed germination The germinability was also different arcording to the pelleting materials. Among the different 58 pelleting materials, kaoline alone, the mixture of bentonite and kaoline, the mixture of bentonite, calcium carbonate and diatomaceous earth #300 were found as the best pelleting materials for welsh onion seeds.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.74.1-74.1
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• 2011

탄소나노튜브는 높은 전기 전도성과 열 전도성을 가지며, 이러한 특성 때문에 21세기를 주도해 나갈 수 있는 차세대 첨단 소재로서 각광을 받고 있다. 또한 최근에는 나노공학기술의 발달로 인하여 획기적으로 높은 열전도도를 나타내는 다중벽 탄소나노튜브(Multi-walled Carbon Nanotubes, MWCNTs)의 대량 생산이 가능하게 되면서 다중벽 탄소나노튜브의 높은 열전도도 특성을 이용하여 탄소나노튜브를 기본 유체 및 기능성 유체에 안정하게 분산 시킨 후 이를 이용하고자 하는 연구가 활발히 진행되고 있으며, 탄소나노튜브를 유체에 안정하게 분산시키기 위한 방법으로는 기계적 분산법, 물리적 흡착에 의한 분산법, 화학적 개질에 의한 분산법이 있다. 따라서 본 연구에서는 이들 분산 방법과 탄소나노튜브 입자의 물성치에 따른 나노유체의 특성을 알아보기 위하여 나노유체의 열전도도와 점도 특성을 비교 분석하였다. 모든 물성치는 같지만 탄소나노튜브의 길이만 다른 두 종류의 다중벽 탄소나노튜브에 각각 계면 활성제(Sodium Dodecyl Sulfate, SDS) 100 wt%와 고분자 화합물(Polyvinyl Pyrrolidone, PVP) 300 wt%를 첨가하여 나노유체를 제조하였으며, 산화처리 된 다중벽 탄소나노튜브(Oxidized Multi-Walled Carbon Nanotubes, OMWCNTs)를 증류수에 초음파 분산하여 산화나노유체를 제조하였다. 나노유체의 열전도도는 전기 전도성 유체의 비정상 열선법(Transient Hot-wire Method)을 이용하여 측정하였고, 나노유체의 점도는 회전형 디지털 점도계를 이용하여 측정하였다. 실험 결과, 상온에서 동일 혼합비의 나노유체를 비교했을 때, 산화나노유체가 SDS 100 wt%, PVP 300 wt%를 혼합한 다른 나노유체보다 높은 열전도도 특성을 보였으며 점도 특성 또한 가장 낮은 것으로 측정되었다. 특히 상온에서 0.1vol%의 산화 CM-100 나노유체는 증류수보다 열전도도가 8.34%가 증가하였고, $10^{\circ}C$의 저온에서는 상온에서 증류수와 비교하여 측정된 열전도도 값보다 0.36%가 감소한 7.98%가 증가함을 보였다. 본 연구를 통하여 얻어진 결과는 높은 열전도도를 필요로 하는 열교환기의 작동유체나 기타 활용 분야에 대한 기초 자료로써 유용한 정보를 제공할 것이라 판단된다.

• Journal of the Korean Chemical Society
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• v.62 no.1
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• pp.30-35
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• 2018

The purpose of this study was to decrease the protein adsorption and improve the function of the hydrophobic acrylic Intraocular lens(IOL). Hydrophobic acrylic intraocular lenses were prepared by using ethyleneglycol phenyletheracrylate (EGPEA), styrene and 2-hydroxyethyl methacrylate (HEMA). Polyvinyl pyrrolidone (PVP) and 2-methacryloyloxyethyl phosphorylcholine (MPC) were used as additives. Water contents, wettability, light transmittance and protein adsorption amount were measured to evaluate the physical properties of the intraocular lens. The water content and wettability of all samples containing additives were increased and the amount of protein adsorption decreased. In particular, samples containing MPC showed a further decrease in protein adsorption. The hydrophobic acrylic intraocular lens with PVP and MPC was found to improve the function of the intraocular lens by reducing the protein adsorption while having basic physical properties.

• Membrane and Water Treatment
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• v.7 no.3
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• pp.257-275
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• 2016

The enantiomeric and racemic effects of tartaric acid (TA) on the properties of polysulfone (PSn) ultrafiltration membranes were studied in terms of morphology and hydrophilicity (HPCT) of membrane. Asymmetric membranes were prepared by direct blending of polyvinyl pyrrolidone (PVP) with D-TA and DL-TA in membrane casting solution. FTIR analysis was done for the confirmation of the reaction of PVP and TA in blended membranes and plain PSn membranes. Scanning electron microscope (SEM), field emission scanning electron microscope (FESEM) and atomic force microscopy (AFM) were used for analyzing the morphology and structure of the resulting membranes. The membranes were characterized in terms of pure water flux (PWF), hydraulic permeability and HPCT. PWF increased from $52L/m^2h$ to $79.9L/m^2h$ for plain and D-TA containing PSn membrane, respectively. Water contact angle also found to be decreased from $68^{\circ}$ to $55^{\circ}$. In Additionally, permeation and rejection behavior of prepared membranes was studied by bovine serum albumin (BSA) solution. A considerable increase in BSA flux (from $19.1L/m^2h$ for plain membrane to $32.1L/m^2h$ for D-TA containing membrane) was observed. FESEM images affirm that the pore size of the membranes decreases and the membrane permeability increases from 0.16 to 0.32 by the addition of D-TA in the membrane. D-TA increases the HPCT whereas; DL-TA decreases the HPCT of PSn membrane. PVP (average molecular weight of 40000 Da) with D-TA (1 wt%) gave best performance among all the membranes for each parameter.

• Elastomers and Composites
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• v.58 no.1
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• pp.44-56
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• 2023

Additive manufacturing (AM) or three-dimensional (3D) printing of metals has been drawing significant attention due to its reliability, usefulness, and low cost with rapid prototyping. Among the various AM technologies, fused deposition modeling (FDM) or fused filament fabrication is receiving much interest because of its simple manufacturing processing, low material waste, and cost-effective equipment. FDM technology uses metal-filled polymer filaments for 3D printing, followed by debinding and sintering to fabricate complex metal parts. An efficient binder is essential for producing polymer filaments and the thermal post-processing of printed objects. This study involved an in-depth investigation of and a fabrication route for a novel multi-component binder system with steel alloy powder (45 vol.%) ranging from filament fabrication and 3D printing to debinding and sintering. The binder system consisted of polyvinyl pyrrolidone (PVP) as a binder and thermoplastic polyurethane (TPU) and polylactic acid (PLA) as a carrier. The PVP binder held the metal components tightly by maintaining their stoichiometry, and the TPU and PLA in the ratio of 9:1 provided flexibility, stiffness, and strength to the filament for 3D printing. The efficacy of the binder system was examined by fabricating 3D-printed cubic structures. The results revealed that the thermal debinding and sintering processes effectively removed the binder/carrier from the cubic structures, resulting in isotropic shrinkage of approximately 15.8% in all directions. The scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) patterns displayed the microstructure behavior, phase transition, and elemental composition of the 3D cubic structure.

• Journal of Bio-Environment Control
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• v.13 no.1
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• pp.8-15
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• 2004

Seedling mechanization of lettuce is known to be difficult due to the small seed size and the irregular seed shape. The purpose of seed pelleting is to make seedling mechanization possible by enlarging the seed size. After that, it can reduce seedling and thinning labours and can also save seeds. According to the results, there were significant differences on the percent germination and day to 50% final germination in accordance with the pelleting polymer. Among the pelleting polymer, gemination of seeds using polynimyl alcohol (PVA) was generally smooth, and followed by polyvinyl pyrrolidone (PVP), hydroxyethyl cellulose (HEC), methyl cellulose (MC), and wteen 80. The germination rate was also different according to the pelleting particulate matters. Generally, percent germination and speed of seed using the mixture of diatomaceous earth, talc and calcium carbonate were higher and faster than using other polleting materials, respectively. Thus, it should be suitable pelleting particulate matter for the pelleting of lettuce seeds. On the other hands germination of seeds using limestone, calcium oxide and benonite were low. The seed size of lettuce after pelleting was 33 times as large as the raw seed size. During the process of seed pelleting, netrient addition induced the decrement on the germination and the delay of germination speed. Also, there was differences in the germinability of pelleted seeds in accordance with the addition of nutrient sources. MS medium was generally lower than monosodium phosphate in inhibition of seed germination. Germination of pelleted seeds after priming was higher than the seeds without the treatment, and also showed the trend of early germination.

• Journal of the Korean Ceramic Society
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• v.39 no.5
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• pp.446-451
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• 2002

Zirconia/alumina mixture powder was spray-dried various degree of dispersion, type of dispersants and powder content in the slurry. The quality of the granule was determined by observation of the granule shapes after spray drying and fracture of intergranular boundaries during pressing. Defect-free granules were obtained from the powders that formed weak flocs in the slurry. The granules, spray-dried from the slurry containing 32.5 vol% powder mixture and PVP as binder, were fractured completely during shaping and the sintered specimens showed a density of 99.7% and a flexural strength of 850 MPa.