• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.357.1-357.1
• /
• 2014

Superhydrophobic WOx nanowire (NW) arrays were fabricated using a thermal evaporation and surface chemistry modification methods by self-assembled monolayer (SAM). As-prepared non-wetting WOx NWs surface shows water contact angle of $163.2^{\circ}$ and has reliable stability in underwater conditions. Hence the superhydrophobic WOx NWs surface exhibits silvery surface by total reflection of water layer and air interlayer. The stability analysus of underwater superhydrophobicity of WOx NWs arrays was conducted by changing hydrostatic pressure and surface energy of WOx NWs arrays. The stability of superhydrophobicity in underwater conditions decreased exponentially as hydrostatic pressure applied to the substrates increased3. In addition, as surface energy decreased, the underwater stability of superhydrophobic surface increased sharply. Specifically, sueprhydrophobic stability increased exponentially as surface energy of WOx NWs arrays was decreased. Based on these results, the models for explaining tendencies of superhydrophobic stability underwater resulting from hydrostatic pressure and surface energy were designed. The combination of fugacity and Laplace pressure explained this exponential decay of stability according to hydrostatic pressure and surface energy. This study on fabrication and modeling of underwater stability of superhydrophobic W18O49 NW arrays will help in designing highly stable superhydrophobic surfaces and broadening fields of superhydrophobic applications even submerged underwater.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.601-601
• /
• 2013

Superhydrophobic W18O49 nanowire (NW) arrays were synthesizedusing a thermal evaporation and surface chemistry modification methods by self-assembled monolayer (SAM). As-prepared non-wetting W18O49 NWs surface shows water contact angle of $163.2^{\circ}$ and has reliable stability in underwater conditions. Hence the superhydrophobic W18O49 NWs surface exhibits silvery surface by total reflection of water layer and air interlayer. The stability analysus of underwater superhydrophobicity of W18O49 NWs arrays was conducted by changing hydrostatic pressure and surface energy of W18O49 NWs arrays. The stability of superhydrophobicity in underwater conditions decreased exponentially as hydrostatic pressure applied to the substrates increased3. In addition, as surface energy decreased, the underwater stability of superhydrophobic surface increased sharply. Specifically, sueprhydrophobic stability increased exponentially as surface energy of W18O49 NWs arrays was decreased. Based on these results, the models for explaining tendencies of superhydrophobic stability underwater resulting from hydrostatic pressure and surface energy were designed. The combination of fugacity and Laplace pressure explained this exponential decay of stability according to hydrostatic pressure and surface energy. This study on fabrication and modeling of underwater stability of superhydrophobic W18O49 NW arrays will help in designing highly stable superhydrophobic surfaces and broadening fields of superhydrophobic applications even submerged underwater.

• The Journal of Advanced Prosthodontics
• /
• v.1 no.1
• /
• pp.47-55
• /
• 2009

STATEMENT OF PROBLEM. A few of studies which compared and continuously measured the stability of various surface treated implants in the same individual had been performed. PURPOSE. We aim to find the clinical significance of surface treatments by observing the differences in the stabilization stages of implant stability. MATERIAL AND METHODS. Eight different surface topographies of dental implants were especially designed for the present study. Machined surface implants were used as a control group. 4 nano-treated surface implants(20 nm $TiO_2$ coating surface, heat-treated 80 nm $TiO_2$ coating surface, CaP coating surface, heat treated CaP coating surface) and 3 micro-treated surface implants [resorbable blast media(RBM) surface, sandblast and acid-etched(SAE) surface, anodized RBM surface] were used as experiment groups. All 24 implants were placed in 3 adult dogs. $Periotest^{(R)}$ & ISQ values measured for 8 weeks and all animals were sacrificed at 8 weeks after surgery. Then the histological analyses were done. RESULTS. In PTV, all implants were stabilized except 1 failed implants. In ISQ values, The lowest stability was observed at different times for each individual. The ISQ values were showed increased tendency after 5 weeks in every groups. After 4 to 5 weeks, the values were stabilized. There was no statistical correlation between the ISQ values and PTV. In the histological findings, the bone formation was observed to be adequate in general and no differences among the 8 surface treated implants. CONCLUSIONS. In this study, the difference in the stability of the implants was determined not by the differences in the surface treatment but by the individual specificity.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2005.10a
• /
• pp.387-392
• /
• 2005

The research was performed to predict the potential landslide with roughness index. It was known that fractal dimension and surface area index can be represented the topography, specially when the natural slopes were rough or rugged. A test site was selected and fractal dimension and surface area index were calculated from the irregular triangle network. Fractal dimension were ranged between $2.016{\sim}2.046$ and surface area index $1.56E+07{\sim}2.59E+07$. Surface area index increased as fractal dimension increased. Slope stability was calculated by infinite slope stability analysis model and was compared to slope stability by fractal and surface area index. In the result, unsafe zones where slope stability is under 1.1 were $5.11{\sim}6.25%$ for the test site. It can be said that fractal dimension and surface area index are a good index to evaluate the slope stability because when fractal dimension and surface area index are greater, then stability of the site is more unsafe.

• Journal of Korean Physical Therapy Science
• /
• v.3 no.2
• /
• pp.963-973
• /
• 1996

The purpose of this study was to evaluate and compare the limits of stability(LOS) at different sensory conditions in normal 20 years of age. The LOS was measured at stable surface, and unstable surface and the subjects stood with the feet contacted and 4 inches between the feet with the eyes open and the eyes closed. In this study, 20 physical therapy major subjects were evaluated at Wonkwang Public Health Junior College. In this study applied the paired t-test, and Kruskal-Wallis 1-way ANOVA to determine the statistical significance of results at 0.01 level of significance. The results were as follows: 1. The mean of lateral limits of stability was b.67 degree at stable surface with the eyes open and standing with the feet contacted. 2. The mean of anteroposterior limits of stability was 9.78 degree at stable surface with the eyes open and standing with the feet contacted. 3. The mean of lateral limits of stability was 15.10 degree at stable surface with the eyes open and standing with 4 inches between the feet. 4. The mean of anteroposterior limits of stability was 11.72 degree at stable surface with the eyes open and standing with 4 inches between the feet. 5. The anterior-posterior and lateral limits of stability significantly decreased with the eyes closed(p<0.01). 6. The anterior-posterior and lateral limits of stability significantly decreased at unstable surface(p<0.01). 7. There was no significant difference of limits of stability as the height and foot length(p>0.01).

• BMB Reports
• /
• v.42 no.12
• /
• pp.829-833
• /
• 2009

Angiogenin is a member of the ribonuclease superfamily that induces the formation of new blood vessels. It has been suggested that the surface loop of angiogenin defined by residues 59-71 plays a special role in angiogenic function (1); however, the mechanism of action is not clearly defined. To elucidate the role of the surface loop on the structure, function and stability of angiogenin, three surface loop mutants were produced in which 14 amino acids in the surface loop of RNase A were substituted for the 13 amino acids in the corresponding loop of angiogenin. The structure, stability and biological functions of the mutants were then investigated using biophysical and biological approaches. Even though the substitutions did not influence the overall structure of angiogenin, they affected the stability and angiogenic function of angiogenin, indicating that the surface loop of angiogenin plays a significant role in maintaining the stability and angiogenic function of angiogenin.

• The Journal of Engineering Geology
• /
• v.33 no.4
• /
• pp.689-699
• /
• 2023

Assessing ground stability is critical to the construction of underground transportation infrastructure. Surface displacement is a key indicator of ground stability, and can be measured using interferometric synthetic aperture radar (InSAR). This study measured time-series surface displacement using permanent scatterer InSAR applied to Sentinel-1 SAR images acquired from January 2017 to June 2023 for the area around a deep underground expressway under construction to connect Mandeok-dong and Centum City in Busan, South Korea. Regions of seasonal subsidence and uplift were identified, as were regions with severe subsidence after summer 2022. To evaluate stability of the ground in the construction area, the mean displacement velocity, final surface displacement, cumulative surface displacement, and difference between minimum and maximum surface displacement were analyzed. Considering the time-series surface displacement characteristics of the study area, the difference between minimum and maximum surface displacement since June 2022 was found to be the most suitable parameter for evaluating ground stability. The results identified highly unstable ground in the construction area as being to the north of the mid-lower reaches of the Oncheon-cheon River and to the west of the Suyeong River at the point where both rivers meet, with the difference between minimum and maximum surface displacement of 40~60 mm.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.12 no.3
• /
• pp.106-115
• /
• 2009

Knowledge about how to stabilize soil structure is essential to conserve soil systems and maintain various biogeochemical processes through soil. In urban area, soil structural systems are degraded with inappropriate management and land use and become vulnerable to erosion. We analyzed the structural changes of surface soils with different land uses, i.e., forests, parks, roadside green area, riparian area, and farmlands (soybean fields), in the Anyang Stream Watershed in order to find the factors influencing the stability of soil structure and the implication for better management of surface soil. Soil organic matter contents of other land use soils were only 18~52% of that in forest soils. Soil organic matter increased the stability of soil aggregates in the order of soybean fields < roadsides < riparian < parks < forests and also reduced soil bulk density (increased porosity). The lowest stability of soybean field soils was attributed to the often disturbance like tillage and it was considered that higher stability of park soils comparing to other land use soils except forests was owing to the covering of soil surface with grass. These results suggest that supply of soil organic matter and protection of soil surface with covering materials are very important to increase porosity and stability of soil structure.

• Journal of Korean Physical Therapy Science
• /
• v.2 no.4
• /
• pp.739-747
• /
• 1995

The purpose of this study was to evaluate and compare the Limits of stability(LOS) in hemiplegic patients who can walking independently. The LOS was measured at stable surface, unstable surface with eye open and eye closed. In this study, 18 out-patients were evaluated who were treated at Yonsei University Medical Center Rehabilitation Hospital. In order to determine the statistical significance of results, T-test, paired t-test, and Kruskal-Wallis 1-way ANOVA were applied at 0.05 level of significance. The results were as follows: 1. The mean of lateral limits of stability was 9.89 degree. 2. The mean of anteroposterior limits of stability was 6.43 degree. 3. There was a significant difference of limits of stability between sound side and affected side(p<0.05). 4. The limits of stability was significantly decreased with eye closed(p<0.05) 5. The limits of stability was significantly decreased at unstable surface(p<0.05). 6. The limits of stability was a significant difference as spasticity degree of ankle plantar flexors(p<0.05). These results showed that the limits of stability in hemiplegic patients was more decreased than that of normal adult. In order to improve the balance in hemiplegic patients, we need to increase the limits of stability.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.43 no.5
• /
• pp.49-54
• /
• 2011

Curtain coating has been considered as the best coating technology because it is a coating technology that forms contour coating layer with better coverage. To increase the curtain stability surfactants are being used. In this study, the effect of a surfactant on the stability of curtain coating colors was examined by evaluating dynamic surface tension with a bubble surface tensiometer. Di-2-ethylhexyl sodium sulfosuccinate was used as a surfactant since it showed low dynamic surface tension at low surface age. And we evaluated the influence of surfactant on coating color properties including surface tension, viscosity and curtain stability. The surface tension of coating color was decreased when surfactant addition was increased up to 0.5 pph, but it was leveled off at 0.3 pph of surfactant addition. With the increase of surfactant addition rate, viscosity of coating color were increased. Micelles formed by surfactant contributed to the increase of the viscosity. Curtain stability was improved with the addition of surfactant until it reached up to 0.5 pph. Excessive addition of surfactant (> 0.5 pph) didn't improve curtain stability. This was attributed to Marangoni effect(self-healing) and decreasing of curtain thickness.