• 한국세라믹학회지
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• 제45권3호
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• pp.157-160
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• 2008

A series of $La_2O_3$-added zincborosilicate glasses was fabricated by systematically varying $La_2O_3$ addition up to 15mol% under the constraint of a ZnO:$B_2O_3$ ratio of 1:2. The degree of water leaching after ball milling of the prepared glasses in water medium was relatively quantified by the change in zinc peak intensity in energy dispersive spectroscopy. 8mol% of $La_2O_3$ was the most efficient addition in inhibiting the glass leaching by water. The role of $La_2O_3$ in inhibiting the leaching was explained in terms of change of structural units in the glass network. When the optimum 8mol% $La_2O_3$-added ZnO-$B_2O_3$ glass was used as sintering aid for $Al_2O_3$, the fabricated alumina-glass composite at $875^{\circ}C$ demonstrated dielectric constant of 6.11 and quality factor of 15470 GHz, indicating the potential of leaching-minimized $La_2O_3-ZnO-B_2O_3$ glass for application to low temperature co-firing ceramic technology.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.325-325
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• 2007

The perovskites in the $LaAlO_3-BaZrO_3$ system (i.e., $(1-x)LaAlO_3-xBaZrO_3$ were fabricated by a solid state reaction and their dielectric properties were investigated. For the compositions of x=0.1~0.9, the mixture of $LaAlO_3$ with a rhombohedral structure and $BaZrO_3$ with a cubic was observed when the sintering was conducted at $1500^{\circ}C$, indicating that the solubility of constituent elements was very low and a narrow solid solution region might exist. The large difference of ionic radii between $La^{3+}$ ion (0.136nm, C.N.=12) and $Ba^{2+}$ ion (0.161nm) or $Al^{3+}$ ion (0.0535nm, C.N.=6) and $Zr^{4+}$ ion (0.072nm) might hinder the mutual substitution. Within the compositions of x=0~0.7, the dielectric constant of the mixture increased with the amount of $BaZrO_3$, i.e., x value, which was in good agreement with the logarithmic mixing rule (In $_{r,i}={\Sigma}v_iln\;_{r,i}$). The increase in $BaZrO_3$ doping decreased $Q{\times}f$ value significantly due to the low $Q{\times}f$ value of $BaZrO_3$ itself, a poor microstructure of the mixture with an increased grain boundary area per volume, and defects in the cation and oxygen sub-lattices which were respectively caused by the evaporation of barium during the sintering process and the substitution of Ba on La-site or Al on Zr-site.

• Bulletin of the Korean Chemical Society
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• 제16권9호
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• pp.805-808
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• 1995

Diacetone-D-glucose was converted into 5-azido-6-O-benzoyl-3-O-benzyl-5-deoxy-1,2-O-isopropylidene-α-D-glucofuranose. After removal of isopropylidene and benzoyl protecting groups, hydrogenation performed reduction of azide and subsequent cyclization by reductive amination to give 3-O-benzyl-1-deoxy nojirimycin in high yield. The second azide group was introduced on 2-carbon by selective substitution reaction, and reduction of azide to amino group gave titled compound.

• 약학회지
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• 제41권2호
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• pp.149-152
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• 1997

Three compounds were isolated from the n-BuOH fraction of buds of Eugenia caryophyllata and their structures were identified as 3,3',4-tri-O-methylellagic acid, 3-O--${\beta}$ -D-glucopyranosyl-3,5,4'-trihydroxy-7,3'-dimethoxyflavone and gallic acid by chemical and spectral evidence.

• 대한수학회논문집
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• 제12권3호
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• pp.539-541
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• 1997

Let X be a smooth projective threefold. Let C be a smooth projective curve and let $f : X \to C$ be a fiber space with connected fiber S. Assume that $q_1(S) = 0$. Then we have $-X(O_C)X(O_S) \leq -X(O_X)$.

• 대한수학회보
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• 제35권4호
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• pp.625-627
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• 1998

Let f: S$\rightarrow$ C be a fiber space with connected fibers. We may have an information about a surface S from the fiber space structure. The result we have is ${\chi}({\mathcal O}_C){\chi}({\mathcal O}_F){\leq}{\chi}({\mathcal O}_S)$.

• Journal of applied mathematics & informatics
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• 제13권1_2호
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• pp.433-440
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• 2003

Artinian O-sequences of codimension 3 and type 3 with length 7 are classified as level or non-level. Some cases are proved to be non-level among the 334 cases which have been suspected to be level.

• Journal of applied mathematics & informatics
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• 제22권1_2호
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• pp.563-568
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• 2006

We introduce how to construct a non-unimodal level O-sequence which has all different local maxima as many as we desire.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2012년도 자성 및 자성재료 국제학술대회
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• pp.63-64
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• 2012

• Journal of applied mathematics & informatics
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• 제7권2호
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• pp.703-707
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• 2000

We give some equivalent conditions about 0-dimensional differentiable level 0-sequencces.