• Biotechnology and Bioprocess Engineering:BBE
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• v.4 no.1
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• pp.66-71
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• 1999

One of the practical limitations with the use of liposomes for delivery of the pharmaceutical substances such antigens is that liposomes are relatively unstable in storage. In order to extend the stability of liposome in storage without affecting their functional activity, solution-type liposomes were dehydrated to form a structurally intact dry liposomes. Comparative immunological evaluation was carried out for both dry and solution-type liposomes containing gag-V3 chimera, consequently it was found that dry liposomes elicited both humoral and cellular response as efficiently as solution-type liposemes did against the same gag-V3 antigen. Especially, long-term stability of the liposomes was remarkably enhanced by the dehydration made to loposomes without a significant change in its ability to elicit immune response in vivo. These results indicate that dry pH-sensitive liposome may become an effective delivery and adjuvant system for general vaccine development.

• Journal of Environmental Science International
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• v.13 no.4
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• pp.435-440
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• 2004

The thiophene or furan-containing hexadentate ligands 1, 12-bis (2-theophene )-2,5,8,ll-tetraazadodecane(Thiotrien ㆍ 4HCl) and 1,12-bis (2-furan)-2,5,8,11-tetraazadodecane(Furatrienㆍ4HC1) were synthesized as their tetrahydrochloride salt and characterized by EA, IR, NMR, and Mass spectrum. Their protonation constants (logK$_{nH}$) and stability constants (logK$^{M}_{L}$ for Cd$^{2+}$, Pb$^{2+}$, $Zn^{2+}$ and Cu$^{2+}$ ions were determined in aqueous solution by potentiometry and compared with 1, 12-bis(2-pyridyl)-2,5,8, 11-tetra-azadodecane(Pytrien) of pyridyl-containing ligand. The effect stability constants of ligands and metal ion for removal of heavy metals in aqueous solution were described.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.41-48
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• 2001

In this study, two factors are simultaneously considered for assessing tunnel face stability: one is the effective stress acting on the tunnel face calculated by upper bound solution; and the other is the seepage force calculated by numerical analysis under the condition of steady-state groundwater flow. The seepage forces calculated by numerical analysis are compared with the results of a model test. From the results of derivations of the upper bound solution with the consideration of seepage forces acting on the tunnel face, it could be found that the minimum support pressure for the face stability is equal to the sum of effective support pressure and seepage pressure acting on the tunnel face. Also it could be found that the average seepage pressure acting on the tunnel face is proportional to the hydrostatic pressure at the same elevation and the magnitude is about 22% of the hydrostatic pressure for the drainage type tunnel and about 28% for the water-proof type tunnel. The model tests performed with a tunnel model had a similar trend with the seepage pressure calculated by numerical analysis. From the model tests it could be also found that the collapse at the tunnel face occurs suddenly and leads to unlimited displacement.

• Journal of the Korean institute of surface engineering
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• v.55 no.2
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• pp.102-119
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• 2022

Gold plating is used as a coating of connecter in printed circuit boards, ceramic integrated circuit packages, semiconductor devices and so on, because the film has excellent electric conductivity, solderability and chemical properties such as durability to acid and other chemicals. As increasing the demand for miniaturization of printed circuit boards and downsizing of electronic devices, several types of electroless gold plating solutions have been developed. Most of these conventional gold plating solutions contain cyanide compounds as a complexing agent. The gold film obtained from such baths usually satisfies the requirements for electronic parts mentioned above. However, cyanide bath is highly toxic and it always has some possibility to cause serious problems in working environment or other administrative aspects. The object of this investigation was to develop a cyanide-free electroless gold plating process that assures the high stability of the solution and gives the excellent solderability of the deposited film. The investigation reported herein is intended to establish plating bath composition and plating conditions for electroless gold plating, with thiomalic acid as a complexing agent. At the same time, we have investigated the solution stability against nickel ion and pull strength of solder ball. Furthermore, by examining the characteristics of the plated Au plating film, the problems of the newly developed electroless Au plating solution were improved and the applicability to various industrial fields was examined. New type electroless gold-plating bath which containing thiomalic acid as a complexing agent showing so good solution stability and film properties as cyanide bath. And this bath shows the excellent stability even if the dissolved nickel ion was added from under coated nickel film, which can be used at the neutral pH range.

• Journal of Pharmaceutical Investigation
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• v.27 no.1
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• pp.23-27
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• 1997

To investigate the effect of L-arginine as stabilizing agent for omeprazole, the degradation rate constant of omeprazole in aqueous solution was determined at 30, 40 and $50^{\circ}C$ with various ratios of L-arginine to omeprazole. The pH of omeprazole solutions was also determined. As the amount of L-arginine increased, the pH of omeprazole solution also increased, and the solution appeared to be more stable. The omeprazole in aqueous solution could be stabilized by more than 15:1 molar ratio of L-arginine to omeprazole. The stability of omeprazole in commercial products using L-arginine or sodium phosphate dibasic as stabilizing agent was investigated. Among the commercial products, the omeprazole product prepared with L-arginine (molar ratio of L-arginine to omeprazole, 20:1) was most stable.

• Journal of applied mathematics & informatics
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• v.36 no.3_4
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• pp.173-179
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• 2018

In this paper, we investigate the stability of positive weak solution for the singular p-Laplacian nonlinear system $-div[{\mid}x{\mid}^{-ap}{\mid}{\nabla}u{\mid}^{p-2}{\nabla}u]+m(x){\mid}u{\mid}^{p-2}u={\lambda}{\mid}x{\mid}^{-(a+1)p+c}b(x)f(u)$ in ${\Omega}$, Bu = 0 on ${\partial}{\Omega}$, where ${\Omega}{\subset}R^n$ is a bounded domain with smooth boundary $Bu={\delta}h(x)u+(1-{\delta})\frac{{\partial}u}{{\partial}n}$ where ${\delta}{\in}[0,1]$, $h:{\partial}{\Omega}{\rightarrow}R^+$ with h = 1 when ${\delta}=1$, $0{\in}{\Omega}$, 1 < p < n, 0 ${\leq}$ a < ${\frac{n-p}{p}}$, m(x) is a weight function, the continuous function $b(x):{\Omega}{\rightarrow}R$ satisfies either b(x) > 0 or b(x) < 0 for all $x{\in}{\Omega}$, ${\lambda}$ is a positive parameter and $f:[0,{\infty}){\rightarrow}R$ is a continuous function. We provide a simple proof to establish that every positive solution is unstable under certain conditions.

• Journal of Pharmaceutical Investigation
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• v.31 no.4
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• pp.273-279
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• 2001

The purpose of this study is to characterize the iontophoretic transport of growth hormone releasing peptides (GHRP-6) through hairless mouse skin from aqueous solution. The effect of various factors, such as pH, poloarity, current profile, current density, current duration, ionic strength, drug concentration, and enhancer application was studied to obtain basic knowledge on the transport. We have also studied the stability of GHRP-6 in solution with/without current. The donor chamber was filled with phosphate buffer solution containing GHRP-6 and the receptor chamber was filled with phosphate buffer solution (pH 7.4). Ag/AgCl electrode was used for their stability and reversibility. At a predetermined time interval, sampling was made and the concentration of drug was analysed using HPLC system. The results showed that, compared to passive flux, the total amount of drug transported increased markedly by the application of anodal current. Cathodal flux was similar to passive flux. Flux increased with the current density, the duration of current application and drug concentration. The effect of enhancers on the flux was studied using hydrophilic (5% N-methyl pyrrolidone) and hydrophobic (5% propylene glycol monolaurate, 5% oleic acid) enhancers. Application of enhancer also increased the flux.

• Journal of Korean Association for Spatial Structures
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• v.18 no.3
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• pp.83-91
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• 2018

In this study, we investigated the dynamic stability of the system and the semi-analytical solution of the shallow arch. The governing equation for the primary symmetric mode of the arch under external load was derived and expressed simply by using parameters. The semi-analytical solution of the equation was obtained using the Taylor series and the stability of the system for the constant load was analyzed. As a result, we can classify equilibrium points by root of equilibrium equation, and classified stable, asymptotical stable and unstable resigns of equilibrium path. We observed stable points and attractors that appeared differently depending on the shape parameter h, and we can see the points where dynamic buckling occurs. Dynamic buckling of arches with initial condition did not occur in low shape parameter, and sensitive range of critical boundary was observed in low damping constants.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.1
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• pp.45-53
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• 2014

For the time integration solution of the impulsive dynamic contact problem of high-speed rotating disks formulated by the finite element technique, the velocity and acceleration contact constraints as well as the displacement contact constraint are imposed for the numerical stability without spurious oscillations. The solution of the present technique is checked by the numerical simulation using the concentric high-speed rotating disks with the clearance and impulsive loading. It is shown that the almost steady state solution agrees with the corresponding analytical solution of the elasticity and that the differentiated constraints are crucial for the numerical stability of such high-speed contact problems of the disks under impulsive loading.

• Structural Engineering and Mechanics
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• v.1 no.1
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• pp.119-135
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• 1993

The paper presents a generalized optimal active control algorithm for earthquake-resistant structures. The study included the weighting matrix configuration, stability, and time-delays for achieving control effectiveness and optimum solution. The sensitivity of various time-delays in the optimal solution is investigated for which the stability regions are determined. A simplified method for reducing the influence of time-delay on dynamic response is proposed. Numerical examples illustrate that the proposed optimal control algorithm is advantageous over others currently in vogue. Its feedback control law is independent of the time increment, and its weighting matrix can be flexibly selected and adjusted at any time during the operation of the control system. The examples also show that the weighting matrix based on pole placement approach is superior to other weighting matrix configurations for its self-adjustable control effectiveness. Using the time-delay correction method can significantly reduce the influence of time-delays on both structural response and required control force.