• 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}$ ).

• 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.

• Journal of Korean Society of Steel Construction
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• v.13 no.4
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• pp.363-372
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• 2001

The objective of this study is to evaluate the $P-{\Delta}$ effect in the case of weak beam unbraced frames by experimental approach. To evaluate $P-{\Delta}$ effect, four specimens were tested under monotonic loading condition. The parameters of tests are the stiffness of column and the axial load ratio. The results show that the value of axial load affects frame stability because $P-{\Delta}$ effects promote the yielding of beam. The maximum lateral load increases in proportion to the increment of column stiffness and rotational stiffness of supports, The collapse mechanism of weak beam unbraced frames is stably formed in the condition of low axial load ratio. The $B_2$ factor of limit state design code does not properly consider the $P-{\Delta}$ effect in inelastic region.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.4
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• pp.45-54
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• 2008

The purpose of this study was to investigate the performance of precast segmental PSC bridge columns with regard to P-delta effects. A model of precast segmental PSC bridge columns was tested under a constant axial load and a cyclically reversed horizontal load. A computer program, RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), was used for the analysis of reinforced concrete structures. In addition to the material nonlinear properties, an algorithm for the problem of large displacement that may result in additional deformation has been formulated using total Lagrangian formulation. This study documents the testing of precast segmental PSC bridge columns under cyclic loading, and presents conclusions based on the experimental and analytical findings.

• Journal of Korean Society of Steel Construction
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• v.15 no.4 s.65
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• pp.457-466
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• 2003

This study aimed to evaluate the stability of steel frames with weak column-strong beam and consider P-effect using the experimental approach. Towards this end, three specimens were tested under monotonic loading condition. Parameters of tests includes the stiffness of the column and the axial load ratio. Result showed that reduction in column stiffness promoted P- effect, which considerably influenced the frame's stability.

• Microbiology and Biotechnology Letters
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• v.18 no.4
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• pp.433-436
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• 1990

The TOL plasmid, pWWO, conjugally transferred from Pseudomonas putida mt-2 was dissociated into TOL* and TOL $\Delta$A in P. putidu PpGl carrying CAM plasmid. The TOL* was integrated into the CAM plasmid, and the resulting plasmid was designated as CAM::TOL*. The introduction of NAH plasmid, belonging to Inc P9 incompatibility group, into P. putida CSTBA carrying CAM::TOLt plasmid and TOL A plasmid did not affect m-toluate catabolism, but resulted in expelling the TOL $\Delta$ plasmid.

• 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.

• 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.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.5 s.39
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• pp.15-24
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• 2004

The purpose of this study is to investigate the inelastic behavior and ductility capacity of reinforced concrete bridge piers including P-delta effects. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In addition to the material nonlinear properties, the algorithm for large displacement problem that may give an additional deformation has been formulated using total Lagrangian formulation. The proposed numerical method for the inelastic behavior and ductility capacity of reinforced concrete bridge piers is verified by comparison with reliable experimental results.

• Journal of the Korean Chemical Society
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• v.25 no.3
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• pp.152-159
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• 1981

The rates of solvolysis for p-nitrobenzyl chloride have been measured by the electric conductivity method in aqueous ethanol from 0.0 to 0. 5 mole fraction of ethanol under various pressures up to 1200bar at 50 and $60{\circ}C$. The activation parameters, ${\Delta}V_\0^{\neq},\ {\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$ are evaluated from the rate constants. The results indicated that ${\Delta}V_\0^{\neq}$ exhibits an extremum behaviors near 0.3 mole fraction of ethanol and ${\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$ near 0.1 mole fraction of ethanol. This behaviors are discussed in terms of solvent structure variation and the pressure dependences of ${\Delta}H^{\neq},\ {\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$ are also discussed individually. The signs of the pressure dependence of ${\Delta}H^{\neq}$${\Delta}S^{\neq}$ are shown to be consistent with those required by the Maxwell relationships for classical thermodynamic systems.