• Elastomers and Composites
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• 제34권5호
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• pp.399-406
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• 1999

Polytetramethylene ether glycol (PTMG)와 4,4'-diphenylmethane diisocyanate (MDI), toluene 2,4-diisocyanate(TDI), isophoron diisocyanate(IPDI)로 polyurethane (PU) prepolymer를 합성하고, dimethylol propionic acid(DMPA)로 쇄연장시킨 후 triethyl amine(TEA)으로 중화시켜서 안정한 수분산성의 음이온성 폴리우레탄을 제조하였다. 음이온성 폴리우레탄의 합성과정에서 쇄연장제의 함량과 중화비에 따른 에멀젼의 유화안정성, 접착강도, 점도, 유리전이온도 및 cast film의 물리적 성질을 UTM, Viscometer와 DSC를 사용하여 검토하였다.

• KSBB Journal
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• 제8권2호
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• pp.178-184
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• 1993

Extractive fermentations with the extract of Jerusalem artichoke in an aqueous-two-phase-system of polyethyleneglycol(PEG) and dextran(Dx) were investigated to obtain the effects of composition of PEG and Dx on both fermentation ,characteristics and partition ratio of alcohol. The specific growth rate of K. Fraglis CBS 1555 increased with a decrease of concentration of PEG and Dx. It augmented along with concentration of initial sugar up to 80g/l but decreased thereafter. The specific production rate of alcohol showed a rising tendency up to 100g/lof initial sugar, whereafter represented a decreasing trend. The partition ratio of alcohol between two phases augmented according to decrease of Dx comic. and increase of PEG cone. regardless of initial sugar concentrations. The ratio, however, decreased with Increment of initial sugar concentration at constant composition of PEG and Dx. The partition coefficient of alcohol had an ascending effect to the increase of PEG cone, but it had little effect on the changes of concentrations of Dx and initial sugar. The present study suggests that the optimum composition of PEG and Dx in the aqueous-two-phase-system by extractive fermentation were around 6.5%(w/v) of PEG and 3%(w/v) of Dx in considerations of emulsion state, sedimentation and separation of two phases, alcohol partition ratio, and specific growth rate.

• Food Science and Biotechnology
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• 제16권4호
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• pp.549-556
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• 2007

The study was carried out to examine on the refiner discharge from Alaska pollock as a collagen resource by characterizing biochemical and functional properties of collagen. The refiner discharge from Alaska pollock surimi manufacturing was a good resource for collagen extraction according to the results of total protein, heavy metal, volatile basic nitrogen, collagen content, amino acid composition, and thermal denaturation temperature (TDT). TDT of acid soluble collagen from refiner discharge showed $20.7^{\circ}C$, which was similar to that of collagen from Alaska pollock muscle and was higher than that of collagen from Alaska pollock skin. TDT of acid-soluble collagen from refiner discharge was, however, lower than those of skin collagens from warm fish and land animal. Acid-soluble collagen from refiner discharge of Alaska pollock could be used as a functional ingredient for food and industrial applications according to the results of water and oil absorption capacities, and emulsion properties. In addition, if the thermal stability of the acid-soluble collagens is improved, collagen from refiner discharge from Alaska pollock could be more effectively used.

• Archives of Pharmacal Research
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• 제26권2호
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• pp.173-181
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• 2003

A polymeric micelle drug delivery system was developed to enhance the solubility of poorly-water soluble drug, biphenyl dimethyl dicarboxylate, DDB. The block copolymers consisting of poly(D,L-lactide) (PLA) as the hydrophobic segment and methoxy poly(ethylene glycol) (mPEG) as the hydrophilic segment were synthesized and characterized by NMR, DSC and MALDI-TOF mass spectroscopy. The size of the polymeric micelles measured by dynamic light scattering showed a narrow monodisperse size distribution with the average diameter less than 50 nm. The MW of mPEG-PLA, 3000 (MW of mPEG, 2 K; MW of PLA, 1K), and the presence of hydrophilic and hydrophobic segments on the polymeric micelles were confirmed by MALDI-TOF mass spectroscopy and NMR, respectively. Polymeric micelle solutions of DDB were prepared by three different methods, i.e. the matrix method, emulsion method and dialysis method. In the matrix method, DDB solubility was reached to 13.29 mg/mL. The mPEG-PLA 2K-1K micelle system was compared with the poloxamer 407 micelle system for their critical micelle concentration, micelle size, solubilizing capacity, stability in dilution and physical state. DDB loaded-polymeric micelles prepared by the matrix method showed a significantly increased aqueous solubility (＞5000 fold over intrinsic solubility) and were found to be superior to the poloxamer 407 micelles as a drug carrier.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.138-143
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• 2005

Finite Element analysis is widely applied to elevated temperature forging processes and shows a lot of information of plastic deformation such as strain, stress, defects, damages and temperature distributions. In highly elevated temperature deformation processes, temperature of material and tool have significant influence on tool life, deformation conditions and productivities. To predict temperature related properties accurately, adequate coefficients of not only contact heat transfer between material and dies but also convection heat transfer due to coolants are required. In most F.E analysis, too higher value of contact heat transfer coefficient is usually applied to get acceptable temperature distribution of tool. For contact heat transfer coefficients between die and workpiece, accurate values were evaluated with different pressure and lubricants conditions. But convection heat transfer coefficients have not been investigated for forging lubricants. In this research, convection heat transfer coefficients for cooling by emulsion lubricants are suggested by experiment and Inverse method. To verify acquired convection and contact heat transfer coefficients, tool temperature was measured for the comparison between measured tool temperature and analysis results. To increase analysis accuracy, repeated analysis scheme was applied till temperature of the tool got to be in the steady-state conditions. Verification of heat transfer coefficients both contact and convection heat transfer coefficients was proven with good accordance between measurement and analysis.

• 항공우주시스템공학회지
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• 제13권5호
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• pp.39-48
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• 2019

회전-고정자 혼합기 내의 난류 유동은 고속으로 회전하는 회전자와 고정자의 상호작용에 의해 발생되는 전단특성을 기반으로 한다. 본 연구에서는 유화연료 관련 회전-고정자 혼합기 시제품 모델에서 회전자와 고정자간의 상호작용에 의한 비정상상태 유동 특성 분석을 ANSYS FLUENT $k-{\varepsilon}$ (RKE) 난류 모델을 MRF 및 SMM에 적용하여 수행하였다. 회전자와 고정자의 경계에서 발생하는 유동 입자들의 거동과 전단 특성 그리고 설계 파라미터에 따른 속도분포와 난류와류소산 등의 경향을 전산유체역학 해석을 통해 예측 비교하여 모델의 효율성을 검증하였다.

• 식품과학과 산업
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• 제51권2호
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• pp.127-135
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• 2018

지방산화는 기본적으로 불포화지방과 산소의 결합이나 이 현상을 제대로 알고 실제 식품에 적용하기 위해서는 지방산화에 미치는 모든 인자들의 화학적 관점(one-electron reduction potential, bond dissociation enthalpy) 뿐만 아니라 물리적 현상(interface, antioxidant polar paradox)을 포괄적으로 이해해야 한다. Invitro실험법에 의해 도출된 산화방지제는 가능성을 보여주는 것이나 실제 식품과 bulk oil, 유화형태, 오르가노젤과 같은고체 상태의 다양한 매트릭스에서는 다른 활성을 나타낸다. 또한 산화방지제의 농도와 다른 물질의 존재에 따라 예상과 다른 활성을 나타내기도 한다. 산화방지제를 활용하여 최종제품의 유통기한을 증가시키기 위해서는 실제 활용될 제품의 매질로 사용해야 한다.

• 한국기계가공학회지
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• 제20권11호
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• pp.115-120
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• 2021

In this study, cigarettes, which are an essential element in the production of tobacco, are generally not cylindrical. The main materials used for cigarettes are generally hemp and pulp. For the production of cylindrical cigarettes, the cigarettes or cylinders are mounted via gluing. This adhesive is a vinyl acetate emulsion, a high-temperature melt adhesive, and is adhered in a cylindrical shape immediately after being linearly applied to the inner surface of the paper roll or a local part. These adhesives are greatly affected by the atmospheric temperature of the manufacturing space in summer and winter. In the summer, even if the adhesive is temporarily adhered, the coagulation time of the adhesive is long, and problems such as deterioration of the adhesive state occur. in the winter, there is a problem that the temperature of the manufacturing space is low and the adhesive force of the adhesive is poor, resulting in defective adhesive products. In order to solve these problems, another heat transfer device is utilized to cure the remaining adhesive to ensure higher adhesiveness.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 1999년도 IFSCC . ASCS 학술대회 발표 논문
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• pp.145-154
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• 1999

A novel retinol derivative, polyethoxylated retinamide (Medimin A) was synthesized, as an anti-aging agent. Collagen synthesis, skin permeation, stability, and toxicity of Medimin A were evaluated and compared with those of retinol and retinyl palmitate. In vitro collagen synthesis was evaluated by quantitative assay of [$^3H$]-proline incorporation into collagenase sensitive protein in fibroblast cultures. For in vitro skin permeation experiments, Franz diffusion cells (effective diffusion area: $1, 766{\;}\textrm{cm}^2$) and the excised skin of female hairless mouse aged 8 weeks were used The stabilities of retlnoids were evaluated at two different temperature ($25{\;}^{\circ}C$ and $40{\;}^{\circ}C$) and under UV in solubilized state and in OW emulsion. To estimate the safety, acute oral toxicity, acute dermal toxicity, primary skin irritation, acute eye irritation and human patch test were performed The effect of Medimin A on collagen synthesis was similar to that of retinol. The skin permeability of Medimin A was higher than those of retinol and retinyl palmitate. The Medimin A was more stable than retinol and retinyl palmitate. Medimin A was nontoxic in various toxicological tests. These results suggest that Medimin A would be a good anti-aging agent for enhancing bioavailability and stability.

• Biotechnology and Bioprocess Engineering:BBE
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• 제3권2호
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• pp.103-108
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• 1998

A hydrophobic substrate triolein was hydrolyzed by lipase in a mono-phase reaction system containing cyclodextrin(CD) as emulsifier. The triolein was transformation to an emulsion-like state in the CD containing reaction system in contrast to the oil-droplet like state without CD due to the formation of an inclusion complex between the lipids and CDs. The hydyrolysis reaction increased substantially in the CD containing reaction system, and the optimum reaction conditions including the amount of lipase, ${\beta}$-CD concentration, and mixing ratio of triolein and ${\beta}$-CD, were determined. The performance of the enzyme reaction in a mono-phase reaction system was compared with that of a two-phase reaction system which used water immiscible hexane as the organic solvent. The role of a CD in the mono-phase reaction system was elucidated by comparing the degree of the inclusion complex formation with triolein and oleic acid, Km and Vmax values, and product inhibition by oleic aicd in aqueous and CD containing reaction systems. The resulting enhanced reaction seems to be caused by two phenomena; the increased accessibility of lipase to triolein and reduced product inhibition by oleic acid through the formation of an inclusion complex.