• Journal of Pharmaceutical Investigation
• /
• v.40 no.3
• /
• pp.187-192
• /
• 2010

We aimed to evaluate the effect of temperature, pH, and light conditions on the stability of porcine placental extract (PPE)-loaded liposomes with different surface charges. The size distribution profiles and in vitro release patterns were investigated by dynamic light scattering method and spectrophotometry. The stability of PPE-loaded liposomes was affected by the surface charges of the liposomes. As compared to neutral and anionic liposomes, cationic liposome formulations showed significantly lower physical stability. At the test storage conditions of different temperatures and pHs, the mean sizes of cationic PPE-loaded liposomes substantially increased. In contrast, neutral and anionic liposomes did not reveal significant changes in mean sizes upon various storage conditions. The neutral and anionic liposomes showed no significant differences in the release profiles of PPE after storage at various temperatures and pHs. Our results indicate that anionic and neutral liposome compositions might be more suitable for the formulations of PPE providing the higher stability.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.1372-1377
• /
• 2003

The stabilization of propane/air lean premixed flames by a heated cylindrical rod is investigated experimentally. The flame stability limits, heat flux, surface temperatures, equivalence ratios, and mixture velocities are measured in order to understand the role of heat flux or surface temperature on the flame stabilization of lean premixed flames. The flame stability limits are lowered by a heated cylindrical rod and extended even below the flammability limit of propane/air mixture when sufficient heat flux is provided. The flame stability limit decreases with the increase of heat flux or surface temperature and decreases with the higher mixture velocity. The diameter of cylindrical rod, however, dose not significantly affect the flame stability limit. The laminar flame speed has been measured for ultra lean propane/air premixed flames. The flame stabilization by a heated cylindrical rod provides the useful tool for the measurement of flame speed under very fuel-lean conditions.

• Journal of the Korean Statistical Society
• /
• v.32 no.4
• /
• pp.337-357
• /
• 2003

This paper introduces new measures for the stability of slope estimation on the second order response surface at a point and on a sphere. As a measure of point stability of slope estimation, we suggest a point dispersion measure of slope variances over all directions at a point. A spherical dispersion measure is also proposed as a measure of spherical stability of slope estimation on each sphere. Some designs are studied to explore the usefulness of the proposed measures. Using the point dispersion measure, another concept of slope rotatability called equally-stable slope rotatability is proposed as a useful property of response surface designs. We provide a set of conditions for a design to have equally-stable slope rotatability.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.16 no.6
• /
• pp.307-312
• /
• 2021

This paper proposes an adaptive time-delayed control approach with the integral sliding-mode surface for the fast convergence rate of robot manipulators. Adaptive switching gain aims to guarantee the system stability in such a way as to suppress time-delayed estimation error in the proposed control approach. Moreover, it makes an effort to increase the convergence ability in reaching the phase. An integral sliding-mode surface is employed to achieve a fast convergence rate in the sliding phase. The stability of the proposed one is proved to be asymptotically stable in the Lyapunov stability. The efficiency of the proposed control approach is illustrated with a tutorial example in robot manipulator, which is compared to that of the existing control approach.

• The Journal of Korean Academy of Prosthodontics
• /
• v.44 no.5
• /
• pp.606-616
• /
• 2006

Purpose: This experiment examined the effect of different surface treatment on the osseointegration and stability of implants. Material and methods: In this study, 40 each of machined, SLA and RBM implants, which are the most commonly used implants, were implanted into the tibia of 20 normal rabbits using $OsseoCare^{TM}$. The rabbits were sacrificed after 1 week, 4 weeks, 8 weeks and 12 weeks for implant stability analysis, removal torque analysis, histologic and histomorphometric analysis. Result : ISQ showed significant difference between Machined and RBM at first week and at 4 weeks. There was significant difference between Machined and both SLA and RBM(p<0.05) but after 8 weeks there were no significant difference between each group. In the removal torque, RBM showd significantly higher values than SLA and Machined surface at 1st week. At 4th and 12th week, there was significant difference between Machined and SLA, RBM(p<0.05). In the bone to implant contact variable, there was no significant difference between each surface treatment method. In the Machined surface group, there was no significant difference between each time interval. but in SLA group, there were significant differences between the 1st week and 12th week and in RBM group, there were significant differences between the 1st week and 8th, 12th week and between 4th and 12th week(p<0.05). The bone area showed significantly higher values in SLA and RBM compared to Machined surface 1st and 8th week and significantly higher values in SLA than Machined surface at the 4th week(p<0.05). Conclusion: The roughened surface of implants showed positive effect in the early stages of implantation and assisted in bone formation After the bone formation stage, there was no statistical difference between Machined and roughened surface groups. In dental implantation, where initial stability is critical to the success of implants, the use of roughened surface implants should assist in reducing the healing period after implantation.

• Journal of Electrochemical Science and Technology
• /
• v.11 no.4
• /
• pp.361-367
• /
• 2020

Recently, layered nickel-rich cathode materials (NCM) have attracted considerable attention as advanced alternative cathode materials for use in lithium-ion batteries (LIBs). However, their inferior surface stability that gives rise to rapid fading of cycling performance is a significant drawback. This paper proposes a simple and convenient coating method that improves the surface stability of NCM using sulfate-based solvents that create artificial cathode-electrolyte interphases (CEI) on the NCM surface. SO_x-based artificial CEI layer is successfully coated on the surface of the NCM through a wet-coating process that uses dimethyl sulfone (DMS) and dimethyl sulfoxide (DMSO) as liquid precursors. It is found that the SO_x-based artificial CEI layer is well developed on the surface of NCM with a thickness of a few nanometers, and it does not degrade the layered structure of NCM. In cycling performance tests, cells with DMS- or DMSO-modified NCM811 cathodes exhibited improved specific capacity retention at room temperature as well as at high temperature (DMS-NCM811: 99.4%, DMSO-NCM811: 88.6%, and NCM811: 78.4%), as the SO_x-based artificial CEI layer effectively suppresses undesired surface reactions such as electrolyte decomposition.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.03a
• /
• pp.331-338
• /
• 1999

In the present study, a searching technique for critical slip surface in two dimensional slope stability analysis is proposed. The failure surface generation and analysis has been usually limited to simple geometric shapes. However, more random surfaces need to be examined for some particular ground conditions. For this purpose, random searching technique is developed using genetic algorithm. The generalized limit equilibrium method is employed as the method of stability analysis. Using this technique, the factor of safety is compared with the result by using simplified Bishop's method. In addition, the convergent trend of fitness value is analyzed.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2003.06a
• /
• pp.129-144
• /
• 2003

Generally, investigation methods of cut slope are conducted only geological surface survey to gain engineering geological data of cut slopes. These methods have many problems such as limitations of investigation for a special area. So geophysical investigations such as geotomography, seismic and electrical resistivity methods have been used to search for failure surface in potential failure slopes or failed slopes. But investigation method using the borehole camera is recently a used method and it is thought that this method is more reliable method than other investigation methods because of being able to see by the eyes. Therefore, this paper was conducted investigations of borings and BIPS(Borehole Image Processing System) to search for potential sliding surfaces and was applied to obtain information of discontinuity on failed and potential failure slope in highway. As the results of BIPS, we could decide potential sliding surface in the slope, conducted to check slope stability and decided slope stability measures.

• Journal of the Korean institute of surface engineering
• /
• v.50 no.3
• /
• pp.155-163
• /
• 2017

In this study, the effects of the concentration of metal ions and the applied current density in the Sn-Ag plating solutions were examined in regards to the resulting composition and morphology of the solder bumps' surface. Furthermore the effect of any impurities present in the methanesulfonic acid used as a base acid in the Sn-Ag solder plating solution on the stability of plating solution as well as the characteristics of the Sn-Ag alloys films was also explored. As expected, the uniform bump was obtained by means of removing impurities in the plating solution. Consequently the resultant solder bump was obtained in an optimal current density of the range of $1A/dm^2$ to $15A/dm^2$, which has acceptable bump shape and surface roughness with 12inch wafer trial results.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.62.2-62
• /
• 2001

In this paper, we present a new time-varying sliding mode system that guarantees stable error convergence. The previous papers have dealt with stability of the time-varying sliding mode system by point-wisely investigating the stability of time-invariant system every time. However, it may be unstable even though it guarantees time-invariant stability every time, We designed the time-varying sliding surface so that the resultant time-varying system on sliding mode may be Stable. The initial sliding surface is obtained so that shifting distance of the surface may be minimized with respect to an initial error, and the intercept is produced so that the surface may pass the initial error.