• 한국세라믹학회:학술대회논문집
• /
• 한국세라믹학회 2003년도 춘계총회 및 연구발표회 초록집
• /
• pp.230.1-230
• /
• 2003

• 한국세라믹학회:학술대회논문집
• /
• 한국세라믹학회 2003년도 춘계총회 및 연구발표회 초록집
• /
• pp.201.1-201
• /
• 2003

• 한국세라믹학회지
• /
• 제22권6호
• /
• pp.21-28
• /
• 1985

The properties of magnetic recording materials largely depend on their shape magnetic anisotropy. The control of their shape and size distribution is very important for improving magnetic properties. The silica-coated goethite$(SiO_2$/$\alpha$-FeOOH=1.5wt%) having acicular shape was prepared. The sillica-coated goethite was heat-treated at 40$0^{\circ}C$~1,00$0^{\circ}C$ 1hr and then reduced at 50$0^{\circ}C$ 2hr. When the silica-coated goethite was heat-treated at 80$0^{\circ}C$ its acicular shape was maintained and its magnetic properties were improved(Hc: 1,325 Oe $\sigma$m:138.8 emu/g, Rs:0.56) However the acicular shape of the paricles was broken for non-coated hematite obtained by dehydration at 80$0^{\circ}C$ They were sintered and showed poor magnetic properties.

• 자원환경지질
• /
• 제32권4호
• /
• pp.399-409
• /
• 1999

Mullitization of kaolinite and dickite was examined with special attention to the influence of polytypism and impurities on the phase transformation. The phase transformation sequence in dickite is identical with that in kaolinite except that cristobalite is crystallized at $50^{\circ}C$ higher temperature in dickite. Difference in phase transformation above $1000^{\circ}C$ in kaolin minerals is attributed to the different crystal structures of metadickite and metakaolinite on the effect of impurities. A part of quartz is transformaed into cristobalite. Spinel-type phase produced in disordered kaolins including illite occurs over a short range of temperatures. Primary mullite is transformed into orthorhombic mullite at higher temperature as well. These results sustain the idea that disintegration of methkaolin and the spinel-type phase supplies extra sillica and promotes the growth of mullite cristobalite.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
• /
• pp.399-400
• /
• 2009

본 연구에서는 염화물 이온을 효율적으로 침투방지 시키기 위한 방법으로, 나노실리카를 이용한 해양콘크리트 방식공법의 현장 적용성에 대하여 검토하였다. 적용결과, 굳지않은 콘크리트에서는 슬럼프 및 공기량에서 큰 차이가 없는 것으로 나타났고, 경화 콘크리트의 염화물 확산 특성에서는 초기 및 후기에서 공히 우수한 효과가 있는 것으로 나타났는데, 이는 나노실리카가 염소이온의 침투 및 확산을 방지하였기 때문인 것으로 판단된다.

• 한국표면공학회지
• /
• 제30권6호
• /
• pp.382-390
• /
• 1997

Good appearance of insulation coating is required for non-oriented silicon steel sheets, The property is influenced by both the chemical composition of coating solution and the species of resin. The composition of inorganic-organic coating was studied to obtain good surface quality for non-oriented silicon steel. The greenish degree of coating surface depended on $Cr^{3+}$ content in the coating layer, which was satisfied when chromate content was more than 54.60 wt. %, in the coating solution. The homogeneous pattern and roughness of the coating surface depended on spreading property of the resin. Surface appearance of the coating could be improved by using resin with good spreading property at the chemical composition of chromate 59.00 wt.%.. resin 34.23wt.%, and etyhylene glycol 6.67 wt.% without colloidal sillica.

• KSBB Journal
• /
• 제9권2호
• /
• pp.147-156
• /
• 1994

A study was carried out for production of a pigment : bluish purple, using a mutant Streptomyces californicus KS-89-7. The mutant was induced from Streptomyces californicus KS-89 with N-methyl-N-nitro-N-nitrosoquanidin(MNNG). It was immobilized on an inert substance made of colloidal sillica and 3.5% sodium alginate with 1 to 10 ratio. The diameter of inert bead was 2mm, and number of immobilized mutant spore was approximately $1.0{\times}10^7$/ml. It was packed in a column reactor and fermentation was conducted with a substrate made of soluble starch 1%, glycerol 1.0%, sodium glutamate 0.1%, sodium nitrate 0.05%, L-prolin 0.025% and with some trace elements. The aeration for production of the pigment was 2.5m1/min with semi-continuous fermentation. The pigment production reached at peak on 8 days of fermentation, and the mutant produced the pigment 1.8 times more than its parent strain with the maximum pigment production of $1.72g/\ell$. The pigment production continued for 24 hours of fermentation, and at the end of the fermentation the mutant produced the pigment $1.52g/\ell$.

• Archives of Pharmacal Research
• /
• 제26권5호
• /
• pp.367-374
• /
• 2003

In the course of screening neuraminidase inhibitors from herbal medicines, Reynoutria elliptica exhibited high inhibitory activity. Four active compounds were isolated from the ethyl acetate soluble fraction by consecutive purification using sillica gel, Sephadex LH-20 chromatography, and recrystallization. The chemical structures of these compounds were identified as 1,3,8-trihydroxy-6-methylanthraquinone (emodin) 1,8-dihydroxy-3-methoxy-6-methylanthraquinone (emodin 3-methyl ether; physcion), 1,3,8-trihydroxy-6-hydoxymethylanthraquinone ($\omega$-hydroxyemodin), and 3,5,4 -trihydroxystilbene (trans-resvertrol) by spectral data including MS, $^1 H-, and ^{13}C-NMR. The IC_{50}$ values of emodin, emodin 3-methyl ether, $\omega$-hydroxyemodin, and trans-resvertrol were 2.81, 74.07, 10.49, and 8.77 $\mu$M, respectively. They did not inhibit other glycosidase such as glucosidase, mannosidase, and galactosidase, indicating that they were relatively specific inhibitors of neuraminidase.

• 한국세라믹학회지
• /
• 제39권10호
• /
• pp.981-987
• /
• 2002

$St\"{o}ber$ process를 이용하여 단분산 콜로이드 실리카를 제조하였다. 초기물질인 TEOS(Tetraethylorthosilicate)와 $NH_4OH$, 에탄올 및 증류수의 함유량을 조절하여 100 nm급, 200 nm급, 300 nm급 크기의 단분산 실리카 입자를 제조할 수 있었고, 제조된 실리카 입자는 Scanning Electron Microscope(SEM) 및 laser scattering particle analyzer를 통해 관찰하였다. Dipcoating 공정을 이용하여 제조된 300 nm 크기의 콜로이드 실리카의 자기 배열성(self-assembly) 형성에 관한 연구를 진행하였다. 다양한 코팅 공정 변수(표면장력, 표면전하, 입자의 함유량)의 조절을 통하여 dip coating시에 자기 배열성 단층막(monolayer)을 형성해 낼 수 있는 조건을 최적화하였고, SEM으로 관찰해 본 결과, 최적 조건 상태에서 비교적 넓은 영역 (1.5 mm ${\times}$ 1.5 mm)에서 hexagonally ordered packing된 콜로이드 입자 결정 단층막을 얻을 수 있었다.

• 한국식품과학회지
• /
• 제22권4호
• /
• pp.405-410
• /
• 1990

국산 대용차 중 시판되고 있는 두충차와 감잎차의 향기성분을 연속증류 추출법으로 추출하여 GC-MS에 의하여 분석, 동정하였다. 두충차에서는 hydrocarbon류 3종, alcohol류 17종, ketone류 15종, aldehyde류 16종, acid류 8종, hetero 고리화합물류 8종과 phenol류 2종을 포함한 총 77종류의 향기성분을 확인하였다. 두충차에 많이 존재하는 ketone류(14.59%) aldehyde류(23.31%)와 hetero 고리화합물(16.71%)들은 두충차의 특징인 달콤하고 한약재에 가까운 향기에 기여한다고 생각된다. 감잎차에서는 hydrocarbon류 10종, alcohol류 17종, ketone류 11종, aldehyde류 13종, ester류 8종, acid류 6종, hetero 고리화합물 5종과 phenol류 1종을 포함한 총 71종을 확인 하였다. 감잎차에는 향기의 기여도가 낮은 hydrocarbon류의 함량(10.40%)이 두충차에 비해 많았고 alcohol류의 함량(25.57%)이 현저하게 많아 은은하고 순한 감잎차의 특유향에 기여한다고 생각된다.