• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1400-1405
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• 2008

Execute surface of the earth geological survey for stability analysis of stealing cutting sides and investigated wide area nature of soil structure. Inflected DIPS that measure discontinuity's direction that develop to slope and is slope stability a wide use program for Stereographic Projection Method analysis that utilize geometrical correlation of stealing four sides and discontinuity surface. It is principle that angle of internal friction that is basis element of stability estimation applies direct shear test result on joint side, Examination is impossible by case execution, suppose by 30 angles that apply more conservatively in base rock slope sides usually and achieved analysis. When analyze, consider discontinuity's various adult that develop in research slope, after conduct first each discontinuity different assay falling into fault, joint, executed stability estimation which synthesize whole discontinuity data. When ailment element is recognized as analysis result, wished to present stability countermeasure way of most suitable to take into account of execution, stability, economic performance.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.6
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• pp.509-519
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• 2015

Mooring stability of floating dock for construction of Ichthys CPF (central processing facilities), an ultra large offshore structure, was studied. Normal and typhoon conditions were considered for mooring analysis. There have been changes in construction stages of the CPF as project progresses. These changes were reflected on the mooring stability analysis for both conditions. In order to secure the mooring stability of the floating dock for Ichthys CPF under typhoon, maximum loads of mooring chains and maximum offset of the floating dock with Ichthys CPF were examined. Also the shapes of the catenary mooring were investigated to check interferences among mooring chains. As it was confirmed that the mooring loads were within SWL (safe working load) of mooring chains and underwater sinkers, the mooring stability of the floating dock for construction of Ichthys CPF was secured. By achieving security of mooring stability of the floating dock, it is assured that Ichthys project is on its way to success.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.3 s.153
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• pp.323-331
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• 2007

Proposed Manta-type Unmanned Undersea Vehicle(UUV) turned out to have the tendency of dynamic instability in vertical plane, and moreover to have that of so strong dynamic stability in horizontal plane as to cause another problem in turning motion due to negative value of sway damping lever. The authors discussed the changes in appendage design for improvement of dynamic stability of UUV in vertical and horizontal planes. As a result, the dynamic stability in vertical plane was improved by increasing the area of horizontal stern planes. and the dynamic stability in horizontal plane was also improved by removal of lower vertical plate and by adjusting the area and position of upper vertical plate simultaneously.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.382-385
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• 2003

Chemical mechanical polishing(CMP) is an essential process in the production of copper-based chips. On this work, the stability of Hydrogen Peroxide($H_2O_2$) as oxidizer of Cu CMP slurry has been investigated. $H_2O_2$ is known as the most common oxidizer in Cu CMP slurry. Copper slowly dissolves in $H_2O_2$ solutions and the interaction of $H_2O_2$ with copper surface had been studied in the literature. Because hydrogen peroxide is a weak acid in aqueous solutions, a passivation-type slurry chemistry could be achieved only with pH buffered solution.[1] Moreover, $H_2O_2$ is so unstable that its stabilization is needed using as oxidizer. As adding KOH as pH buffering agent, stability of $H_2O_2$ decreased. However, stability went up with putting in small amount of BTA as film forming agent. There was no difference of $H_2O_2$ stability between KOH and TMAH at same pH. On the other hand, $H_2O_2$ dispersion of TMAH is lower than that of KOH. Furthermore, adding $H_2O_2$ in slurry in advance of bead milling lead to better stability than adding after bead milling. Generally, various solutions of phosphoric acids result in a higher stability. Using Alumina C as abrasive was good at stabilizing for $H_2O_2$; moreover, better stability was gotten by adding $H_3PO_4$.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.357.1-357.1
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• 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
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• 2013.02a
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• pp.601-601
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• 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.

• Journal of the Korean Wood Science and Technology
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• v.44 no.2
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• pp.184-190
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• 2016

Recently, wood is attracting attention as green building interior decoration material. When wood is used as building interior decoration material, excellent dimensional stability and thermal performance is required. In this study, superheated steam treatment process and thermal compression process were applied to flat sawn Pinus koraiensis wood panel in order to improve dimensional stability and thermal performance. According to results of this study, superheated steam treatment process and thermal compression process improve thermal performance and dimensional stability of wood, especially in tangential direction. The spring back in radial direction reduces the effect of thermal compression on dimensional stability of wood in radial direction.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.865-876
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• 2015

Voltage stability is one of the most critical security issues which has not yet been well resolved to date. In this paper, an analytical method called PQ plane analysis with consideration of the reactive power capability of wind turbine generator and the wake effect of wind farm is proposed for voltage stability study. Two voltage stability indices based on the proposed PQ plane analysis method incorporating the uncertainties of load-increasing direction and wind generation are designed and implemented. Cases studies are conducted to investigate the impacts of wind power incorporation with different control modes. Simulation results demonstrate that the constant voltage control based on reactive power capability significantly enhances voltage stability in comparison of the conventional constant power factor control. Some meaningful conclusions are obtained.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.1
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• pp.75-77
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• 2002

Stability theorem for nonlinear systems with slowly varying inputs is extended to systems with slowly varying and small jump inputs.

• Bulletin of the Korean Mathematical Society
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• v.39 no.1
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• pp.53-62
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• 2002

We discuss the $\hbar-stability$ of perturbed Volterra difference systems by means of the resolvent matrix and discrete inequalities.