• Polymer(Korea)
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• v.38 no.5
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• pp.676-681
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• 2014

Licorice, widely used as a herbal medicine, has flavonoids such as liquiritin and its aglycone, liquiritigenin that show anti-oxidant and anti-inflammatory properties. Licorice flavonoid-loaded cellulose hydrogels were prepared as carriers for skin drug delivery, and their properties were investigated. The porous cellulose hydrogel was made by reacting cellulose with epichlorohydrin as a cross-linking agent in NaOH/urea(1~10%) solutions. Through studies on the rheological properties and water uptake of the hydrogel, a NaOH/urea(6%) solution was established as being optimum for the synthesis of the cellulose hydrogel containing liquiritin and liquiritigenin. Scanning electron microscopy (SEM) observations of a cross-section of the prepared hydrogel indicated its porosity. In particular, in skin permeation experiments using a Franz diffusion cell, hydrogel containing the licorice flavonoids showed remarkable transdermal permeation compared to the control group. These results indicate that porous cellulose hydrogel is a potential drug delivery system to enhance the skin permeation of licorice flavonoids.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.175-180
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• 2016

The fluorine-containing modified polyurea was synthesized using the PTPE-diol to improve the ozone-resistance. Three types (PFDIA-10C, PFDIA-20C, PFDIA-30C) of the modified polyurea containing the fluorine content from 10 wt% to 30 wt% were prepared. After ozone treatment on the prepared films, the weight loss of film was investigated and analyzed the film properties such as hardness, wear resistance, tensile stress, elongation, etc. Also, the film surfaces were observed by the optical microscopy after ozone-resistance tests at 10 ppm for 336 h. It was shown that the defects such as the cracking, the bleaching and the mass loss were reduced and the ozone-resistance of films were improved when the contents of PFPE-diol are more than 20 wt%. It was found that the intensity of O-H peak in PFDIA compounds confirmed by FT-IR was decreased as fluorine contents were increasing.

• The Korean Journal of Pesticide Science
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• v.5 no.3
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• pp.58-62
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• 2001

New benzenesulfonylurea derivatives possessing ${\beta}$-hydroxyalkyl subgroup were synthesized and found to have interesting herbicidal activity in greenhouse screening.

• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.147-150
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• 1998

A series of new benzenesuIfonylurea derivatives possessing ${\alpha}$-diketone or ${\alpha}$-keto ester moiety as an ortho substituent were synthesized by employing new methodology starting from 2-bromophenyl methoxymethyl sulfide and some of them were found to have good herbicidal activity at foliar application.

• The Korean Journal of Pesticide Science
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• v.6 no.1
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• pp.45-48
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• 2002

New benzenesulfonylurea derivatives possessing bicyclic ketal subgroup were synthesized and shown to have interesting herbicidal activities under upland greenhouse screening.

• Elastomers and Composites
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• v.46 no.2
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• pp.158-163
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• 2011

Rigid polyurethane foam (PUF) was synthesized with different contents of aliphatic polyester polyol, aromatic polyester polyol and aliphatic polyether polyol to know change of properties under sea water. UTM(universal testing machine), DSC(differential scanning calorimetry), hardness meter and FT-IR(Fourier transform spectroscopy) were used to study the PUF`s physical properties under sea water. Compressive strength and hardness of PUF decreased with increasing the content of aromatic polyester polyol under sea water as aging. According to the results of IR spectral analysis, reduction of urethane and urea peak was found and allophanate and biuret peak increased. Although glass transition temperature of PUF increased, mechanical properties of PUF decreased under sea water, because PUF gets brittle when crosslink density increase.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.60-65
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• 1998

핵융합로 증식재용 Li$_2$TiO$_3$ 분말을 자발착화연소합성법으로 합성하였다. Li질산염과 Ti 질산염이 혼합된 전구용액은 연소반응을 위하여 가열되는 동안 침전물이 형성 되었지만 카르복실산기(carboxylic acid group)와 아민기(amine group)를 지닌 글라이신(glycine)이나 카르복실산기만을 가진 구연산(citric acid)과 아민기만을 가진 우레아(urea)를 흔합한 연료를 사용한 경우에는 연소합성반응이 일어나 분말을 쉽게 합성할 수 있었다. 또한 형성된 분말은 별도의 하소공정이 없더라도 원하는 결정상이 형성되었으며, 합성편 Li$_2$TiO$_3$ 분말은 비표면적이 15 $m^2$/g으로 약 30nm의 크기를 지닌 미세한 입자이었다.

• Journal of Adhesion and Interface
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• v.13 no.2
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• pp.85-88
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• 2012

In this paper, the curing reaction of UF resins was investigated by a real time FT-IR method. The curing temperature range of the UF resin was $25{\sim}200^{\circ}C$. It was found that the reactions of UF resin at different temperatures resultedin resins with different cross-linked structures. A real time FT-IR spectroscopy can be considered as a good routine analytical tool for following the progress of UF resin curing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.361-362
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• 2005

Antimony doped tin oxide(ATO) nano powders have been synthesized by homogeneous precipitation method using $SnCl_4\cdot5H_2O$ for precursor, $SbCl_3$ as doped material and urea. The hydrolysis of urea and conductive mechanism and Heat treatment was performed at the temperature from $500^{\circ}C$ to $700^{\circ}C$ in air. The ATO nano powders are characterized by means of Thermogravimetry differential thermal analyzer (TG-DTA), X-ray diffraction (XRD), Brunauer, Emmett, and Teller adsorption (BET), Scanning electron microscopy (SEM) ATO nano powders with an average size of nm and the highest surface area 129 $m^2g^{-1}$ are obtained.

• Textile Coloration and Finishing
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• v.2 no.1
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• pp.14-20
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• 1990

The cotton fabrics were treated with formaldehyde in the presence of zinc nitrate catalyst and urea. The effects of HCHO concentration, urea concentration, catalyst ratio, cure time and cure temperature on the physical properties of fabrics were studied. Cotton fabric finished with HCHO and urea had the lower tensile strength and tear strength than untreated one. These strength losses resulted from tighter oxymethylene crosslinks. The enhanced wrinkle recovery for fabric treated with formaldehyde in the presence of urea was indicative of the formation of urea-formaldehyde polymer. These experimental conditions were set up according to table of orthogonal arrays.