• 한국분말재료학회지
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• 제15권2호
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• pp.101-106
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• 2008

The objective of the present study is to investigate the increase in the functional characteristics of a substrate by the formation of a thin coating layer. Thin coating layers of $Ti_5Si_3$ have high potential because $Ti_5Si_3$ exhibits high hardness. Shock induced reaction synthesis is an attractive fabrication technique to synthesize uniform coating layer by controlling the shock wave. Ti and Si powders to form $Ti_5Si_3$ using shock induced reaction synthesis, were mixed using high-energy ball mill into small scale. The positive effect of this technique is highly functional coating layer on the substrate due to ultra fine substructure, which improves the bonding strength. These materials are in great demand as heat resisting, structural and corrosion resistant materials. Thin $Ti_5Si_3$ coating layer was successfully recovered and showed high Vickers' hardness (Hv=1183). Characterization studies on microstructure revealed a fairly uniform distribution of powders with good interfacial integrity between the powders and the substrate.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1080-1081
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• 2006

In this investigation, $B_4C$ based ceramic composites were fabricated by in-situ reaction hot pressing using $B_4C$, TiC SiC powder as starting materials. The reaction synthesized composites by hot pressing at $1950^{\circ}C$ was found to posses very high relative density. The reaction synthesized $B_4C$ composites comprise $B_4C$, $TiB_2$, SiC and graphite by the reaction between TiC and $B_4C$. The newly formed $TiB_2$ and graphite was embedded both inside grain and at grain boundary $B_4C$. The mechanical properties of reaction synthesized $B_4C-TiB_2-SiC$-graphite composites were more enhanced compared to those of monolithic $B_4C$.

• 약학회지
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• 제30권2호
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• pp.104-105
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• 1986

Full details of a modified Friedlander quinoline synthesis, which utilizes a Wadsworth-Emmons-Horner reaction as a key step, will be described.

• Bulletin of the Korean Chemical Society
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• 제23권8호
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• pp.1173-1176
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• 2002

• Bulletin of the Korean Chemical Society
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• 제27권7호
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• pp.976-980
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• 2006

The synthesis of 4'-phenyl and 1'-methyl doubly branched carbocyclic nucleoside was accomplished from 2-hydroxy acetophenone. The 4'-phenyl group was installed via a [3,3]-sigmatropic rearrangement reaction, and the carbonyl addition of methylmagnesium bromide was used to introduce the 1'-methyl group. Cyclization of divinyl 9 was performed using $2^{nd}$ generation Grubbs catalyst. The coupling of cyclopentenol 12$\alpha$ with 6-chloropurine by Mitsunobu reaction and desilylation was used to synthesize the target nucleoside 15.

• Bulletin of the Korean Chemical Society
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• 제25권5호
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• pp.668-672
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• 2004

This paper reports the stereoselective synthesis of a novel nucleoside, 4'-methyl branched and bicyclo [3.1.0] hexane locked-nucleoside 12, using a sequential [3,3]-sigmatropic rearrangement/carbene cycloaddition reaction/Curtius reaction strategy with a high stereoselectivity.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3382-3384
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• 2010

A new synthetic route to ($\pm$)-aspidospermidine was devised, starting from the cycloadduct of 3-ethyl-5-bromo-2-pyrone with vinyl sulfide through a tandem conjugate addition-alkylation sequence. The requisite 3-ethyl-5-bromo-2-pyrone was prepared via the C3-selective Pd-catalyzed coupling reaction with $Et_3Al$-dimethylaminoethanol complex.

• 대한화학회지
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• 제66권1호
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• pp.9-14
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• 2022

An efficient method for the synthesis of 1-aminophthalans has been developed. The intramolecular oxa-Mannich reaction of 1,3-dihydro-2-benzofuran-1-ols with p-toluenesulfonylamine in the presence of Cs₂CO₃ as a base, without using any catalyst, provided the desired 1-aminophthalans in moderate to good yields.

• 한국미생물·생명공학회지
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• 제19권5호
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• pp.444-449
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• 1991

Pullulanase의 역반응능을 이용하여 maltose와 $\beta$-cyclodextrin으로부터 maltosyl-$\beta$-cyclodextrin을 중합합성하기 위한 최적효소반응조건을 검토하였다. Maltose와 $\beta$-CD를 기질로 maltosyl-$\beta$-CD을 합성하였을 경우, 기질의 농도 70( w/w, 70g/100ml $H2_O$ ), malto-loigo당 /$\beta$-CD의 혼합비 12.7, 그리고 사용효소량 350 units/100ml일 때 최대전융인 43(w/w, g branched-CD/g CD)를 얻었고, 생성량은 2.31g/100ml였다. Maltosyl-$\beta$-CD의 효소합성의 적정 pH 및 온도는 각각 4.9와 $60^{\circ}C$ 였다. 또한 maltose와 $\alpha ,\beta$-그리고 $\gamma$-CD 각각을 기질로하여 maltosyl $\Alpha, \beta$ 그리고 $\gamma$-CD를 합성하였을 경우 전환율은 51.8, 42.6, 그리고 48.1로써, 생성량은 각각 2.8, 2.3 그리고 2.6g/100ml였다.

• 한국세라믹학회지
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• 제35권12호
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• pp.1329-1336
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• 1998

A twt -step carbothermal reduction scheme has been employed for the synthesis of SiC whiskers in an Ar or a H2 atmosphere via vapor-solid two-stage and vapor-liquid-solid growth mechanism respectively. It has been shown that the whisker growth proceed through the following reaction mechanism in an Ar at-mosphere : SiO2(S)+C(s)-SiO(v)+CO(v) SiO(v)3CO(v)=SiC(s)whisker+2CO2(v) 2C(s)+2CO2(v)=4CO(v) the third reaction appears to be the rate-controlling reaction since the overall reaction rates are dominated by the carbon which is participated in this reaction. The whisker growth proceeded through the following reaction mechaism in a H2 atmosphere : SiO2(s)+C(s)=SiO(v)+CO(v) 2C(s)+4H2(v)=2CH4(v) SiO(v)+2CH4(v)=SiC(s)whisker+CO(v)+4H2(v) The first reaction appears to be the rate-controlling reaction since the overall reaction rates are enhanced byincreasing the SiO vapor generation rate.