• Wind and Structures
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• 제20권1호
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• pp.95-115
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• 2015

Wind effects on roofs are usually considered by equivalent static wind loads based on the equivalence of displacement or internal force for structural design. However, for large-span spatial structures that are prone to dynamic instability under strong winds, such equivalent static wind loads may be inapplicable. The dynamic stability of spatial structures under unsteady wind forces is therefore studied in this paper. A new concept and its corresponding method for dynamic instability-aimed equivalent static wind loads are proposed for structural engineers. The method is applied in the dynamic stability design of an actual double-layer cylindrical reticulated shell under wind actions. An experimental-numerical method is adopted to study the dynamic stability of the shell and the dynamic instability originating from critical wind velocity. The dynamic instability-aimed equivalent static wind loads of the shell are obtained.

• KSBB Journal
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• 제26권5호
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• pp.381-385
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• 2011

Studies were made to improve the stability of astaxanthin which has application limitations caused by light and thermal stability problems in spite of its strong anti-oxidant property. Astaxanthin was extracted from Haematococcus pluvialis with supercritical carbon dioxide. Liposomal encapsulation of astaxanthin to improve the stability was made with high pressure homogenizer. The narrow size distribution was observed with astaxanthin liposomes. Tests on light and thermal stabilities resulted that the liposormal encapsulation improved the stability of astaxanthin for cosmeceutical purposes.

• Geomechanics and Engineering
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• 제17권6호
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• pp.573-581
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• 2019

Excavation of underground cavern and shaft was proposed for the construction of a ventilation facility in an urban area. A shaft connects the street-level air plenum to an underground cavern, which extends down approximately 46 m below the street surface. At the project site, the rock mass was relatively strong and well-defined joint sets were present. A kinematic block stability analysis was first performed to estimate the required reinforcement system. Then a 3-D discontinuum numerical analysis was conducted to evaluate the capacity of the initial support and the overall stability of the required excavation, followed by a 3-D continuum numerical analysis to complement the calculated result. This paper illustrates the application of detailed numerical analyses to the design of the required initial support system for the stability of underground hard rock mining at a relatively shallow depth.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1787-1793
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• 2018

The power conversion efficiency of perovskite solar cells has reached 23.3%. Although significant developments have been made through intensive studies, the stability issue is still challenging. Passivation of perovskite solar cells with a transparent polymer provides better stability; however, there are a few disadvantages of organic polymer such as low thermal stability, weak adhesion and the lack of water retention ability. In this work, we prepared a dual Parylene-F/C layer with 3-methacryloxypropyltrimethoxysilane, A-174, to combine the advantages of organic and inorganic materials. As a result, A-174 treated dual Parylene-F/C layer demonstrated improved passivation effects compared to a single Parylene layer due to the strong binding of Parylene and the water retention ability by $SiO_2$ formed from A-174. This synergetic effects can be expanded to the combination of other organic materials and organosilane compounds.

• 대한기계학회논문집
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• 제11권1호
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• pp.145-153
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• 1987

본 논문에서는 예혼합동축분류화염에 있어서 재순환역 안으로의 기체(공기, 연료, 혼합기) 주입과 2차공기의 족회가 화염안정성, 화염형상 및 재순환역에 미치는 영향을 명확히 하였다.

• 대한조선학회논문집
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• 제44권3호
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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.

• Geomechanics and Engineering
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• 제17권3호
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• pp.279-285
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• 2019

The process of slope stability analysis is one of the most important stages in design of some civil and mining projects. Bimslopes are made from bimrocks (block-in-matrix rocks) where rocky blocks are distributed in a bonded matrix of finer texture. These kind of slopes are often seen in weathered and near-surface depths. Previous studies have shown that VBP (Volumetric Block Proportion) is one of the most significant factors affecting bimrocks strength and consequently the stability of bimslopes. In this paper, the influence of block inclinations on bimslope stability have been investigated. For this purpose, 180 theoretical models have been made with various VBPs, all of them have a specified block size distribution. These bimslopes contain blocks with differing dips relative the slope inclination. Also for each kind of block inclination, 10 different blocks arrangements have been modeled. The Finite Element Method (FEM) was used to analysis the stability of these bimslopes models. The results showed the inclination of blocks has a strong impact on the Safety Factor and stability of bimslopes. When the difference in angle of dip of blocks relative to the slope angle is maximum, the Safety Factor of bimslopes tends to be a maximum compared with the matrix-only state. Furthermore, with increasing VBP of bimslopes stability increases. The graphs obtained from this study could be used for preliminary guidance in the projects design with bimslopes.

• 한국전문물리치료학회지
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• 제28권3호
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• pp.208-214
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• 2021

Background: The CKCUES test evaluates the functional performance of the shoulder joint. The CKCUES test scores CKC exercises of the upper limbs to examine shoulder stability. Although the CKCUES test provides quantitative data on functional ability and performance, no study has determined the relationship between CKCUES scores and SA and TB muscle strength. Objects: The objective of this study is to determine the relationship between the CKCUES test scores and the strength of the SA and TB muscles in the CKCUES and unilateral CKCUES tests. Methods: Sixty-six healthy male volunteers participated in the study. A Smart KEMA strength sensor measured SA and TB muscle strength. Two parallel lines on the floor indicated the initial hand placement to start CKCUES tests. For 15 seconds, the subject raises one hand and reaches over to touch the supporting hand, then returns to the starting position. Results: The correlation between the CKCUES test scores and the strength of the SA was strong (r = 0.650, p < 0.001), and the TB was moderate (r = 0.438, p < 0.001). The correlation between the unilateral CKCUES test and the strength of the SA of the supporting side was strong (r = 0.605, p < 0.001), and swing side was strong (r = 0.681, p < 0.001). The correlation between the unilateral CKCUES test and the strength of the TB of the supporting side was moderate (r = 0.409, p < 0.001), and swing side was moderate (r = 0.482, p < 0.001). Conclusion: Our study showed that the CKCUES test had a strong association with isometric strength of SA and moderate association with that of TB. These findings suggest that the CKCUES test can evaluate the function of the SA. Moreover, the unilateral CKCUES test can evaluate unilateral shoulder function.

• 한국철도학회논문집
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• 제10권3호
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• pp.271-277
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• 2007

The Korean Tilting Train eXpress (TTX) development program is in progress for the purpose of running speed or passenger's comfort improvement at the curved track. However, the speed up and light weight of train make poor the dynamic safety of the TTX in strong cross wind. In this paper, 3-dimensional numerical analysis on the flow field around the TTX under strong cross wind is performed for each operating condition, such as the train speed, cross wind speed, tilting/nontilting condition, and so on. Due to the strong cross wind, the pressure distribution around the train becomes asymmetric, especially at the leading car. Asymmetrical pressure distribution causes the side force and strong unstability. The side force on the train is proportional to the train speed and cross wind speed. Based on the numerical results, the overturning coefficients are predicted for investigation of the train stability, and all of them are less than the critical value, 0.9. The results in this study would be a good data for providing importance to judgement of cross wind safety of TTX.

• 한국안전학회지
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• 제21권2호
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• pp.107-113
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• 2006

Earthquake motion is one of the most significant influence factors on the slope stability. In this paper, an effective stress analysis with the elasto-plastic model was carried out to investigate the behavior of the slope stability subjected to the successive two strong earthquake motions, fore and main shock. The major influence of fore shock to the slope stability was considered as the existence of the residual excess pore water pressure. The paper presents the influence of the existence of the fore shock to slope stability using the numerical analyses. In conclusion, the excess pore pressure by the fore shock was not dissipated during the 7hrs of consolidation. By this residual excess pore water pressure, the factor of safety at the sliding face showed the minimum values, and the deformations of slope was large when compared with the case that considered the main shock only. Furthermore, the minimum of the factor of safety came out after the end of the earthquake motion.