• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.521-526
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• 2007

Density functional calculations have been performed for the reactions of perfluoroalkylsilane and alkylsilane with silica surfaces. The (100) and (111) surfaces of ${\beta}-cristobalite$ are used as two possible models of the hydroxylated amorphous silica surface. This is the crystalline phase of silica with density and refractive index closest to those of amorphous silica. Moreover, two ${\beta}-cristobalite$ surfaces have the two types of silanol groups, namely the single silanols and the geminal silanols. We investigate the possible adsorption structure and formation energy of perfluoroalkylsilane and alkylsilane molecules with two type of silanol groups. The results will be compared with cluster and slab model.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.786-789
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• 1997

Ti-6Al-4V has been used widely in biomedical field. But because of its toxicity, the ${\beta}$ stabilizing element, V, in Ti-6Al-4V has been replaced by Nb, Ta. Ti-10Ta-10Nb has been developed for biomedical applications. The fatigue crack propagation behavior of Ti-alloy(Ti-10Ta-10Nb) was investigated, in comparison with that of pure Ti. In order to better understand the fundamental fatigue behavior of Ti-10Ta-10Nb, rotating bending fatigue tests have been carried out. Ti-10Ta-10Nb has a better fatigue strength than pure Ti. In this paper, fatigue life has been predicted with Nisitani's equation of the fatigue crack propagation that can be established by measuring fatigue crack growth rates.

• Bulletin of the Korean Chemical Society
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• 제23권5호
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• pp.749-757
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• 2002

Chiral oxazolidin-2-one is easily prepared from D-mannitol and demonstrated to undergo highly diastereoselective alkylation reactions via lithium imide Z-enolates of its N-acyl derivatives to afford ${\alpha}-branched$ products. Evans syn and non-Evans sy n aldol products were also selectively obtained using this new auxiliary in high diastereomeric purity by simply changing the stoichiometry of TiCl4 and the nature of the amine base. Also, this new auxiliary is employed in diastereoselective Staudinger-type ${\beta}-lactam$ syntheses. Using 2-chloro-1-methylpyridinium iodide as the dehydrating agent, the reaction of auxiliary tethered acetic acid with trans imines gave the desired ${\beta}-lactams$ with cis-selectivity.

• 품질경영학회지
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• 제25권1호
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• pp.69-79
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• 1997

We consider the semiparametric linear errors-in-variables model: yi=(${\alpha}+{\beta}ui+{\varepsilon}i$, xi=ui＋${\varepsilon}i$ i=1, …, n where (xi, yi) stands for an observation vector, (ui) denotes a set of incidental nuisance parameters, (${\alpha}$ , ${\beta}$) is a vector of regression parameters and (${\varepsilon}i$, ${\delta}i$) are mutually uncorrelated measurement errors with zero mean and finite variances but otherwise unknown distributions. On the basis of a simple small-sample low-noise a, pp.oximation, we propose a new method of comparing the mean squared errors(MSE) of the various competing estimators of the true regression parameters ((${\alpha}$ , ${\beta}$). Then we show that a class of estimators including the classical least squares estimator and the maximum likelihood estimator are consistent and first-order efficient within the class of all regular consistent estimators irrespective of type of measurement errors.

• 품질경영학회지
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• 제22권2호
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• pp.89-97
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• 1994

We consider the linear calibration model: $y_1={\alpha}+{\beta}x_i+{\sigma}{\varepsilon}_i$, i = 1, ${\cdots}$, n, $y={\alpha}+{\beta}x+{\sigma}{\varepsilon}$ where ($y_1$, ${\cdots}$, $y_n$, y) stands for an observation vector, {$x_i$} fixed design vector, (${\alpha}$, ${\beta}$) vector of regression parameters, x unknown true value of interest and {${\varepsilon}_i$}, ${\varepsilon}$ are mutually uncorrelated measurement errors with zero mean and unit variance but otherwise unknown distributions. On the basis of simple small-sample low-noise approximation, we introduce a new method of comparing the mean squared errors of the various competing estimators of the true value x for finite sample size n. Then we show that a class of estimators including the classical and the inverse estimators are consistent and first-order efficient within the class of all regular consistent estimators irrespective of type of measurement errors.

• 대한수학회지
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• 제49권2호
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• pp.379-394
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• 2012

Given an almost complex structure ($\mathbb^{C}^m$, J), $m\geq2$, that is defined by setting $\theta^{\alpha}=dz^{\alpha}+a_{\beta}^{\alpha}d\bar{z}^{\beta}$, ${\alpha}=1,\ldots$,m, to be (1, 0)-forms, we find conditions on ($a_{\beta}^{\alpha}$) for the existence of holomorphic functions an classify the almost complex structures by type ($\nu$,q). Then we determine types for several examples in $\mathbb{C}^2$ and $\mathbb{C}^3$ including the natural almost complex structure on $S^6$.

• Journal of Chest Surgery
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• 제33권9호
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• pp.766-769
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• 2000

The long QT syndromes have been classified into acquired or inheritary forms, both of which are associated with a characteristic type of life-threatening polymorphic ventricular tachycardia called torsade de points. Beta-adrenergic blocker is the first cholic treatment, but in those whom cardiac events are not prevented by $\beta$-blockade, left thoracic sympathetic ganglionectomy may be useful in selected cases. A 50-year-old woman had an recurrent syncopal attack in which she was unconscious for 1-2 min and 1-2 times a month for 10 years. The EKG revealed that QT & QTc intervals were 744 and 632 msec respectively. Treatment with Beta-adrenergic blocker and calcium channel blocker was ineffective in preventing recurrence of syncopal spell. Therefore, she underwent left thoracic sympathetic ganglionectomy with thoracoscope. During the 9 months after operation, she was free of syncopal episodes and is doing well.

• Bulletin of the Korean Chemical Society
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• 제28권9호
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• pp.1519-1522
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• 2007

A new oleanane-type triterpenoid estersaponin, bodinierin C (1), along with two known saponins, mazusaponin I (2) and ciwujianoside C (3), were isolated from the water-soluble part of the root barks of Elsholtzia bodinieri. The structure of bodinierin C was characterized by spectroscopic means and chemical hydrolysis as 3β -Ocaffeoyl- 23-hydroxylechinocystic acid 28-O-α -L-rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6)-β- D-glucopyranosyl ester. The known compounds were identified by comparing their spectral data with those of authentic samples or data reported in the literature. All compounds were firstly isolated from Elsholtzia bodinieri family.

• 약학회지
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• 제34권1호
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• pp.34-39
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• 1990

The alkaloidal constituents of Commelina communis(Commelinaceae) were investigated. From the ether soluble alkaloidal fraction, three ${\beta}-carboline$ type alkaloids were isolated by chromatographic purification process. Their chemical structures were identified as $1-carbomethoxy-{\beta}-carboline$, norharman and harman from the physicochemical data, which were newly isolated from this plant.

• Mycobiology
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• 제38권2호
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• pp.108-112
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• 2010

To investigate the possible roles of LAMMER kinase homologue, Lkh1, in Schizosaccharomyces pombe, whole proteins were extracted from wild type and lkh1-deletion mutant cells and subjected to polyacrylamide gel electrophoresis. Differentially expressed proteins were identified by tandem mass spectrometry (MS/MS) and were compared with a protein database. In whole-cell extracts, 10 proteins were up-regulated and 9 proteins were down-regulated in the mutant. In extracellular preparations, 6 proteins were up-regulated in the lkh1+ null mutant and 4 proteins successfully identified: glycolipid anchored surface precursor, $\beta$-glucosidase (Psu1), cell surface protein, glucan 1,3-$\beta$-glucosidase (Bgl2), and exo-1,3 $\beta$-glucanase (Exg1). These results suggest that Lkh1 is involved in regulating cell wall assembly.