• Membrane Journal
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• v.8 no.3
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• pp.157-169
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• 1998

The effects of solvents (DMAc, NMP, 1,4-dioxane) and nonsolvents ($H_2O$, Methanol, n-hexane) on the morphology of 6FDA-p-TeMPD polyimide membrane, prepared by the wet phase inversion method, were studied. In the polymer/solvent/nonsolvent ternary system, the binodal curve, the coagulation value and the relative light transmission were measured, and the solubility parameter difference was calculated. The onset state and rate of liquid-liquid alemixing were predicted and the morphology of membrane was analyzed. It is found that the finger-like pores are formed within discontinuous polymer nodules when the binoclal curve is close to the polymer-solvent (P-S) axis, the coagulation value is small, the reduction of light transmission is easy to occur and the order of solubility parameter difference ($\Delta \delta_{i-j}$) is $\Delta \delta_{S-NS} > \Delta \delta_{P-NS} > \Delta \delta_{P-S}$. The dense skin with small nodules and the sponge type sublayer with macrovoid are formed in the case that the binodal curve is distant from the P-S axis, the onset time of liquid-liquid demixing is long and the order of $\Delta \delta_{i-j}$ is $\Delta \delta_{P-NS} >(\Delta \delta_{S-NS} < > \Delta \delta_{P-S})$. The thick layer of fine nodule coagulation and loosely grown sublayer of nodules appear when the binodal curve is distant from the P-S axis, the onset time of liquid-liquid demixing is very long and the order of $\Delta \delta_{i-j}$가 $\Delta \delta_{S-NS} > (\Delta \delta_{P-NS}$\lessgtr$ > (\Delta \delta_{P-NS} < >)\Delta \delta_{P-S}$ ).

• East Asian mathematical journal
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• v.18 no.2
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• pp.271-282
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• 2002

Let R be a ring with an endomorphism $\sigma$ and a derivation $\delta$. An ideal I of R is ($\sigma,\;\delta$)-ideal of R if $\sigma(I){\subseteq}I$ and $\delta(I){\subseteq}I$. An ideal P of R is a ($\sigma,\;\delta$)-prime ideal of R if P(${\neq}R$) is a ($\sigma,\;\delta$)-ideal and for ($\sigma,\;\delta$)-ideals I and J of R, $IJ{\subseteq}P$ implies that $I{\subseteq}P$ or $J{\subseteq}P$. An ideal Q of R is ($\sigma,\;\delta$)-semiprime ideal of R if Q is a ($\sigma,\;\delta$)-ideal and for ($\sigma,\;\delta$)-ideal I of R, $I^2{\subseteq}Q$ implies that $I{\subseteq}Q$. The ($\sigma,\;\delta$)-prime radical (resp. prime radical) is defined by the intersection of all ($\sigma,\;\delta$)-prime ideals (resp. prime ideals) of R and is denoted by $P_{(\sigma,\delta)}(R)$(resp. P(R)). In this paper, the following results are obtained: (1) $P_{(\sigma,\delta)}(R)$ is the smallest ($\sigma,\;\delta$)-semiprime ideal of R; (2) For every extended endomorphism $\bar{\sigma}$ of $\sigma$, the $\bar{\sigma}$-prime radical of an Ore extension $P(R[x;\sigma,\delta])$ is equal to $P_{\sigma,\delta}(R)[x;\sigma,\delta]$.

• Journal of the Korea Society of Computer and Information
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• v.17 no.11
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• pp.189-196
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• 2012

This paper proposes Swap algorithm for solving Dynamic Economic Dispatch (DED) problem. The proposed algorithm initially balances total load demand $P_d$ with total generation ${\Sigma}P_i$ by deactivating a generator with the highest unit generation cost $C_i^{max}/P_i^{max}$. It then swaps generation level $P_i=P_i{\pm}{\Delta}$, (${\Delta}$=1.0, 0.1, 0.01, 0.001) for $P_i=P_i-{\Delta}$, $P_j=P_j+{\Delta}$ provided that $_{max}[F(P_i)-F(P_i-{\Delta})]$ > $_{min}[F(P_j+{\Delta})-F(P_j)]$, $i{\neq}j$. This new algorithm is applied and tested to the experimental data of Dynamic Economic Dispatch problem, demonstrating a considerable reduction in the prevalent heuristic algorithm's optimal generation cost and in the maximization of economic profit.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.4 s.74
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• pp.375-387
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• 2006

Different from the previous studies which investigated seismic P-$\Delta$ effect in slender columns though comparison of response spectra according to stability coefficients obtained from the analyses based on the assumed moment-curvature relationship, the axial force and P-$\Delta$ effect in RC columns are investigated on the basis of the layered section method which can effectively consider the changes of stiffness and yield strength due to the application of axial force in RC members. Practical ranges of slenderness and stability coefficient are assumed, and sixty sets of horizontal/vertical earthquake inputs are used in the analysis. From the parametric study, it is noted that the maximum deformation of the slender RC column is hardly affected by P-$\Delta$ effect or vortical earthquake but dominantly affected by the applied axial force. Therefore, it can be concluded that no additional consideration for the P-$\Delta$ effect and vortical earthquake is required in the seismic design of a slender RC column if the axial force effect is taken into account in the analysis and design procedures.

• Solar Energy
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• v.10 no.3
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• pp.46-52
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• 1990

Novel a-Si solar cells with delta-doped(${\delta}x$-doped) P-layer have been fabricated to enhance the hole concentration of the P-layers. The ${\delta}-$doped P-layer consists of very thin B sheets of 0.1-0.5 atomic layers and undoped a-SiC multi-layers. B-layers were prepared by photo-CVD and pyrolysis technique. The structural, optical and electrical characteristics of the delta-doped P-layer films were evaluated by means of FTIR, AES and SIMS. As the results of this study, it was found that the ${\delta}$-doped P-layer showed much superior optical and electrical characteristics than those of conventional uniformly B-doped a-Si layers. 12.5% energy conversion efficiency was achieved for the Cell with ${\delta}$-doped P-layer.

• Journal of the Korean Chemical Society
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• v.57 no.6
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• pp.665-671
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• 2013

The solubilization of p-bromophenol by the micellar system of TTAB(tetradecyltrimethylammonium bromide) and the micellization of TTAB were studied by the UV-vis spectrophotometric method simultaneously. And the effects of temperature on these properties have been measured for the thermodynamic study. The results show that the ${\Delta}G_s{^o}$ and ${\Delta}H_s{^o}$ values are negative and the ${\Delta}S_s{^o}$ values are positive for the solubilization of p-bromophenol within the measured range. On the other hand, the ${\Delta}G_m{^o}$ values are negative and the ${\Delta}H_m{^o}$ and ${\Delta}S_m{^o}$ values are positive for the micellization of TTAB. The effects of additives such as n-butanol and NaCl have been studied also for both properties and the relationship between these two properties has been also studied. From the results, we can postulate the solubilization site of p-bromophenol in the micelle.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.324-329
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• 2015

First-principles investigations on the hybrid one dementional hexagonal hybrboron-nitride nano ribbons (BNNRs) with a armchair graphene nano-ribbons(AGRNRs), are presented. Electronics properties of the mixed armchair BNC nano-ribbon (BNCNRs) structure show control of a band gap on all cases at the special K-point. And we have studied, the band gap is direct in all cases. The band gap of mixed ABNCNRs could be divided into three groups (${\Delta}3p$, ${\Delta}3p+1$ and ${\Delta}3p+2$) and decrease with the increase of the width. Also these results show similar to the AGNRs case. Different from the band gap value ordering of AGNRs (${\Delta}3p+1$ > ${\Delta}3p$ > ${\Delta}3p+2$), the ordering of ABNCNRs is ${\Delta}3p$ > ${\Delta}3p+1$ > ${\Delta}3p+2$. The discrepancy may come from the differences between the edges of AGRNRs and the boundaries of hybrid BNCNRs. In addition, the bandgap of ABNCNRs are much smaller than those of the corresponding AGNRs. Our results show that the origin of band gap for BNCNRs with armchair shaped edges arises from both quantum confinement effect of the edges. These results similar to thecase of AGNRs. These properties of hybrid BN/C nano-ribbon structure may offer suitable bandgap to develop nnanoscale electronics and solar cell beyond individual GNRs and BNNRs.

• Journal of the Korean Chemical Society
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• v.48 no.3
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• pp.254-260
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• 2004

The reaction rates of para-substituted benzoyl chlorides ($p-CH_3$, p-H, $p-NO_2$) with pyridine have been measured employing the conductometry method in acetonitrile. The pseudo first-order and second-order rate constants were determined at various pressures and temperatures. The activation parameters (${\Delta}V{\ddagger},\;{\Delta}{\beta}{\ddagger},\;{\Delta}H{\ddagger},\;{\Delta}S{\ddagger},\;{\Delta}G{\ddagger}$) and the Hammett ${\rho}$-values are determined from the values of rate constant. The values of ${\Delta}V{\ddagger},\;{\Delta}{\beta}{\ddagger}\;and\;{\Delta}S{\ddagger}$ are all negative. The Hammett ${\rho}$-values are positive for the substrate (${\rho}_Y$) over the given pressure range. The results of kinetic studies, for the pressure and substituent changes, show that these reactions are proceeded by a typical $SN_2$reaction mechanism and its bond formation is favored with elevating pressure.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.3
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• pp.97-103
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• 2004

Most of the columns in centrally braced steel frame buildings are usually designed as the gravity columns to reduce connection cost. For a rational seismic performance evaluation of centrally braced steel frame buildings, it is important to properly incorporate in the analysis  the P-${\Delta}$ effects arising from the gravity columns. An effective scheme for the P-${\Delta}$ effects modeling due to the gravity columns was illustrated based on the concept of fictitious leaning column. Seismic performance evaluation of inverted V braced steel frames with or without P-${\Delta}$ effects modeling was conducted by following the FEMA 273 NSP (Nonlinear Static Procedure). The problem in estimating dynamic P-${\Delta}$ modification factor (C3) in FEMA 273 was discussed. The results of this study indicated that the P-${\Delta}$ effects should be included in the seismic performance evaluation of centrally braced steel frames. This study also showed that the inverted V braced frames, retrofitted by applying the tie bars to redistribute the inelastic demand over the height of the building, exhibit significantly improved seismic performance.

• Communications of the Korean Mathematical Society
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• v.9 no.3
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• pp.669-670
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• 1994

Let $E \to M$ be a hermitian holomorphic vector bundle over a compact (complex) hermitian manifold M of complex dimension n, and let $$ d"_p(E) : 0 \to A^{p,0}(E) \to A^{p,1}(E) \to \cdots \to A^{p,n}(E) \to 0$$ be the Dolbeault complex. Then $A^{p,q}(E)$ become a prehibert space so that the formal adjoint $\delta"$ of $d"$ and the "Laplacian" $\Delta" = \delta" d" + d" \delta"$ are defined.quot; d" + d" \delta"$ are defined.;$ are defined.