• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1337-1345
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• 2018

The reliability of power transmission and distribution depends up on the consistency of insulation in the high voltage power transformer. In recent times, considering the drawbacks of conventional mineral oils such as poor biodegradability and poor fire safety level, several research works are being carried out on natural ester based nanofluids. Earlier research works show that sunflower oil has similar dielectric characteristics compared with mineral oil. BIOTEMP oil which is now commercially available in the market for transformers is based on sunflower oil. Addition of nanofillers in the base oil improves the dielectric characteristics of liquid insulation. Only few results are available in the literature about the insulation characteristics of nano modified natural esters. Hence understanding the influence of addition of nanofillers in the dielectric properties of sunflower oil and collecting the database is important. Considering these facts, present work contributes to investigate the important characteristics such as partial discharge, lightning impulse, breakdown strength, tandelta, volume resistivity, viscosity and thermal characteristics of $SiO_2$ nano modified sunflower oil with different wt% concentration of nano filler material varied from 0.01wt% to 0.1wt%. From the obtained results, nano modified sunflower oil shows better performance than virgin sunflower oil and hence it may be a suitable candidate for power transformer applications.

• Bulletin of the Korean Chemical Society
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• 제9권3호
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• pp.149-152
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• 1988

A mixture of (Z,Z)-3,13-octadecadien-1-yl acetate(1) and its (E,Z)-isomer(2), the sex pheromone of the cherry tree borer, Synanthedon hector Butler was synthesized. (Z)-11-Octadecen-1-al(3) was prepared from 1,10-decandiol. The Wittig reaction the above aldehyde3 with carboethoxymethylenetriphenylphosphorane, or the Wadsworth-Emmons reaction of the above aldehyde3 with the anion of triethylphosphonoacetate gave ethyl (Z,Z)-2,13-octadecadienoate and its (E,Z)-isomer. Deconjugative protonation of ethyl (Z,Z)-2,13-octadecadienoate and its (E,Z)-isomer with potassium hexamethyldisilazide followed by aqueous ammonium chloride work-up afforded stereoselectiv디y ethyl (E,Z)-3,13-octadecadienoate and its (Z,Z)-isomer, respectively, of which stereoselectivity was adjusted to give the product in the required ratio. Exposure of the above deconjugated ester to excess lithium aluminium hydride resulted in formation of the penultimate (Z,Z)-3,13-octadecadien-1-ol and its (E,Z)-isomer. Acetylation of the desired alcohols afford the final products, (Z,Z)-3,13-octadecadien-1-yl acetate(1) and its (E,Z)-isomer(2).

• Natural Product Sciences
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• 제5권2호
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• pp.80-84
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• 1999

Peroxynitrite is a cytotoxic intermediate produced by the reaction between the superoxide anion radical and nitric oxide. Flavonoids (afzelin, quercitrin and quercetin 3-O-sambubioside), and chlorogenic acid and its methyl ester obtained from leaves of loquat (Eriobotrya japonica) have recently been shown to scavenge 1,1-diphenyl-2-picrylhydrazyl radical and to inhibit lipid peroxidation in mouse liver homogenate. The aim of this study is to investigate the inhibitory effects of the above components on peroxynitrite produced stimulated by 3-morpholinosydnonimine (SIN-1) to produce superoxide anion radical and nitric oxide at the same time. In addition, the present study tests whether or not the components directly scavenge peroxynitrite itself. The results showed that the components with the aromatic ortho-dihydroxyl groups (catechol) were more potent inhibitors of peroxynitrite formation by SIN-1. In particular, the methyl ester form of chlorogenic acid showed the most potent inhibition. At $5\;{\mu}M$ concentration, the order of minimizing peroxynitrite formation were : methyl chlorogenic acid > quercitrin > quercetin 3-O-sambubioside > chlorogenic acid > afzelin. Authentic peroxynitrite was directly scavenged by the components in a manner similar to peroxynitrite formation by SIN-1. In particular, when compared with penicillamine as a positive control, methyl chlorogenate was as effective in inhibiting peroxynitrite formation and approximately 2 times more effective in scavenging an authentic peroxynitrite. These results demonstrate therefore, that components extracted from the leaves of Eriobotrya japonica effectively scavenged peroxynitrite.

• 한국수산과학회지
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• 제27권3호
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• pp.272-281
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• 1994

양식 농어에 대한 사료 carotenoids의 대사와 체색개선에 미치는 영향을 검토하기 위하여 ${\beta}$-carotene, lutein ester, astaxanthin, astaxanthin monoester 및 astaxanthin diester의 첨가사료로서 8주간 사육하여 표피의 carotenoid성분을 분석, 비교 검토한 결과는 다음과 같다. 농어 표피의 carotenoid색소는 tunaxanthin획분과 lutein이 주성분을 이루고 있으며, 그 외 ${\beta}$-carotene, a-cryptoxanthin, zeaxanthin 및 ${\beta}$-carotene type triol이 소량으로 존재하였다. 한편, 천연산은 양식산에 비하여 tunaxanthin과 lutein의 함유비가 높은 반면 ${\beta}$-carotene의 함유비가 낮은 경향을 보여 서로 차이를 보였다. Carotenoid의 축적율은 astaxanthin monoester 첨가구에서 가장 높게 나타나서 체색선명화의 효과가 컸었으며, 그 다음으로 astaxanthin, astaxanthin diester첨가구의 순으로 나타났다. 사육시험후 각 시험구의 carotenoid함량과 조성으로 보아, 농어의 carotenoid대사경로는 astaxanthin이 ${\beta}$-carotene type triol, zeaxanthin, lutein을 거쳐 tunaxanthin으로 되는 환원적대사과정을 가지는 것으로 추정할 수 있었다.

• Natural Product Sciences
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• 제17권4호
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• pp.342-349
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• 2011

This study was performed to determine the composition of phenolic substances contained in the leaves of Cirsium setidens (Compositae), validate the high-performance liquid chromatography (HPLC) method, and determine the in vivo sedative effect of the main component pectolinarin. Six phenolic compounds isolated from C. setidens were spectroscopically identified as chlorogenic acid (1), hyperoside (2), 3,4-di-O-caffeoylquinic acid (3), caffeic acid methyl ester (4), linarin (5), and pectolinarin (6) and then used as standard compounds for HPLC analysis. HPLC proved to be precise, accurate, and sensitive for the simultaneous analysis of the phenolic substances. In particular, six compounds showed good regression ($R^2$ > 0.999) within test ranges and recovery was in the range of 95.4 - 104.8%. The content of pectolinarin was considerably higher (156.48 mg/g) than those of other phenolic substances including the other flavone glycoside, linarin (18.99 mg/g). The contents of other phenolic substances, in order, were chlorogenic acid (8.41 mg/g), 3,4-di-O-caffeoylquinic acid (5.74 mg/g), hyperoside (4.33 mg/g), and caffeic acid methyl ester (0.51 mg/g). Oral administration with compound 6 (10 and 20 mg/kg) enhanced the sleeping time induced by pentobarbital in mice, indicating that it has a sedative effect.

• 한국어병학회지
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• 제20권1호
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• pp.33-40
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• 2007

제주지역 양식 넙치의 주요 세균성 질병의 일종인 연쇄구균증 원인균 Streptococcus iniae 및 Streptococcus parauberis에 대한 생물학적 특성을 시험하였다.온도별 성장 시험결과 S. parauberis 균주는 10℃ 배양조건에서 성장이 이루어졌으나 S. iniae 균주의 경우는 10℃에서는 성장이 확인되지 않았으며, 용혈성 시험결과에서는 S. iniae 균주의 경우에만 β용혈성을 나타내었다.생화학적특성 시험결과 acetoin production test (VP test), hippurate hydrolysis test (HIP test)에서는 S. parauberis 균주의 경우에만 양성반응을 보여 두 균주사이에 뚜렷한 차이를 보였다.또한 α-D-glucose, D-mannose, D-psicose, D-trehalose, pyruvatic acid methyl ester, glycerol은 두 균주 모두 기질로 이용하였으나 L-lactic acid는 S. iniae 균주만이 이용하였고, β-methyl-D-glucoside의 경우는 S. parauberis 균주만이 기질로 이용하는 것으로 나타났다.병원성 시험결과, S. iniae는 급성감염 형태를 보인 반면에 S. parauberis는 만성 감염형태를 보임으로써 차이를 나타내었다.

• 생약학회지
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• 제31권2호
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• pp.149-156
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• 2000

Atherosclerosis is emerging as one of the major causes of death in Korea as well as Western societies. In the present study; hypocholesterolemic and antiatherogenic effects of the ethanol extract of Allium victorialis Makino was investigated using the conventional rabbit and the cholesteryl ester transfer protein (CETP)-transgenic mouse model. Hypercholesterolemia was induced by feeding high cholesterol diet to the animals for 30 days and they were then fed with high cholesterol diet containing 0.5% of the A. victorialis extract for additional 30 (or 40) days. In the experiment using rabbits, treatment with the A. victorialis extract significantly decreased plasma total cholesterol, low density lipoprotein (LDL)-cholesterol, triglyceride levels and lipid peroxidation compared to those in the control group. Total cholesterol contents in the liver and the heart were also significantly decreased. Lipid staining of the aorta isolated from the rabbits showed that treatment with the A. victorialis extract decreased formation of atheromatous plaques on the intima of the aorta. In the experiment employing CETP transgenic mouse model, treatment with the A. victorialis extract decreased the levels of plasma total cholesterol and the tissue triglyceride levels in the heart. These results demonstrated that the ethanol extract of A. victorialis lowered serum cholesterol levels, tissue lipid contents and accumulation of cholesterol in the artery.

• Composites Research
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• 제30권1호
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• pp.59-64
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• 2017

향상된 특성을 갖는 환경친화적인 복합재료의 개발은 고분자재료의 미래에 있어 필수적이며, 부분적으로 또는 완전히 재생가능한 기지재 또는 보강재에 단지 몇 %의 첨가제를 첨가함으로써 쉽게 제작할 수 있다. 본 연구에서는 마닐라삼 섬유를 보강재로, 비닐에스터를 기지재로 사용하였으며, VARTM 공정을 이용하여 복합재료를 제조하였다. 또한 마닐라삼 섬유의 알칼리표면처리를 수행하고, APP, HNT를 난연제를 첨가함으로써 기계적 물성과 난연 물성을 향상시키고자 하였다. 실험을 통하여 표면처리가 천연섬유의 친수성을 감소시키고 소수성인 기지재와의 계면접착력을 향상시켰으며, 이는 개발된 복합재료의 기계적 물성 향상을 이끌었다. 유사하게, 복합재료의 난연성도 난연제의 함량이 증가함에 따라 크게 향상되는 결과를 얻을 수 있었다.

• 한국응용과학기술학회지
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• 제35권2호
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• pp.560-567
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• 2018

화장품산업에서 보습 효과를 오랫동안 지속시키기 위해 보습제로 히아루론산, 글리세린 등 많은 원료가 개발과 연구되어지고 있다. 이번 연구에서는 보습제 원료가 아닌 계면활성제를 변경함에 따라 피부의 보습 및 경피수분손실량의 변화에 대해 연구 하였다. 특별히 계면활성제의 종류는 천연계면활성제, Lecithin 계면활성제, Polyglyceryl ester계열 계면활성제, PEG계열 계면활성제, PEG계열 W/O 계면활성제 등으로 이 들의 계면활성제의 변화에 따라 피부의 보습 및 경피수분손실량의 변화를 확인하였고, 계면활성제 중에서 Lecithin surfactant를 사용했을 때 가장 우수한 결과 값을 확인 하였다.

• 한국식품과학회지
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• 제32권2호
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• pp.448-453
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• 2000

천연물로부터 U937 세포주를 사용한 caspase-3 유도저해물질을 탐색한 결과 머위(Petasites japonicum)를 선발하였다. 머위의 메탄올 추출물로부터 Sephadex LH-20 column chromatography, HPLC 등을 사용하여 저해물질을 분리하였으며, UV, EIMS, 1H-NMR, $^{13}C-NMR$, HMBC등의 기기분석을 실시한 결과 [3-(3,4-dihydroxyphenyl)-2-oxopropyl] ester로 동정되었다. 이 물질은 $IC_{50}\;8\;{\mu}g/ml$의 농도로 U937 세포주의 etoposide에 의한 caspase 3 유도를 저해하였으며, DNA fragmentation도 저해하였다. 또한 1,1-diphenyl-2-picrylhydrazyl(DPPH) 라디칼 소거능을 나타내었다.