• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.9_10
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• pp.1153-1159
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• 2003

The effects of changing aqueous solution properties by nonionic surfactants on wetting behavior and water retention properies of hydrophobic PET (polyethylene terephthalate) fabric were reported. The aqueous solution properties were diversified by mixing and diluting two nonionic surfactants, i.e., sorbitan monolaurate (Span 20) and polyoxyethylene(20) sorbitan monolaurate (Tween 20). The surface wetting properties ($cos{\theta}$) of PET fabric were greatly improved by adding $10^{-1}g/dl$ Tween 20 and further improved by mixing Span 20 to the system. The water retention properties (W) of PET fabric were also greatly increased by addition of $10^{-1}g/dl$ Tween 20. In diluted surfactant systems, the $cos{\theta}'s$ were increased with decreasing surface tension of aqueous liquids. The ratios of aqueous liquid retained in the pore structure to liquid retention capacity (W/H) were also increased with decreasing surface tension, however, W/H values were dramatically increased right after critical micelle concentration (cmc). The existence of micelles was important for the retention of aqueous liquids in the fabric. The critical surface tension of PET fabric used was found to be 28.7dyne/cm.

• KSBB Journal
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• v.17 no.3
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• pp.295-301
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• 2002

The effects of nonionic surfactant (SPAN 20) on the desulfurization process by Rhodococcus sp. strain IGTS8 have been investigated at various oil/water ratios, pHs and concentrations of surfactant. The hexadecane containing DBT was employed as model oil. The presence of surfactant in the oil/water mixture stabilized the oil/water interface, thus enhanced the efficiency of desulfurization. The volume percentages of oil in the oil/water mixture were 30, 50 and 70%. The concentrations of surfactant were varied from 0 to 0.33 wt% relative to water phase. In general, the biodesulfurization efficiencies were decreased as the concentration of SPAN 20 and the volume percentage of oil phase increased.

• Journal of Korean Association for Spatial Structures
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• v.10 no.1
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• pp.59-66
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• 2010

Among the protected horticulture facilities in Korea, 99.2% are pipe-framed green houses and most of them are structurally vulnerable single-span type green houses. This study examined peak external pressure coefficient for the roof surface of a green house group composed of single-span and a multiple-span green houses. According to the results of the experiment, the distribution of peak external pressure coefficient was around 30% higher in the single-span greenhouse than in the multi-span ones. The external pressure coefficient for the roof surface of the vinyl house group was, in all of the three vinyl houses, was around 20%-30% higher than that for single-span greenhouses.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.04a
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• pp.105-110
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• 1992

This study deals with the effect of a series of moving trucks on the Dynamic Load Factor (DLF). The DLF is calculated by investigating the load effect of moving trucks. Therefore, analytical models for frocks, bridge, and road profiles were developed and dynamic structural analysis computer program were developed. Then the DLFs are calculated as a ratio of maximum dynamic load effect and maximum static load effect. Trucks used in this study are 5 axle semi tractor-trailer with the weight of 36 and 54 ton. Simply supported prestressed concrete box girder bridges with 20 and 40m span length are selected. From the results of the DLF for various headway distances, they show a very scattered and relatively high values of the DLF in case of a 20m span length bridge. For a 40m span length bridge, the results show less scattered and small increase of the DLF compared to a 20m span length bridge.

• Journal of the Korean Society of Clothing and Textiles
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• v.24 no.7
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• pp.1065-1072
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• 2000

The molecular areas and the interfacial tension behavior of ten nonionic surfactants, i.e., Span 20 and Tween 20, 40, 60. 80, 21, 61, 81, 65, & 85 are tested to assay their effects on the wetting and liquid retention properties of hydrophilic and hydrophobic fibrous materials. The molecular areas at water/air interface are derived from Gibbs’adsorption equations. The following conclusions are drawn from the results: 1) Span 20 is efficient in lowering the interfacial tension and effective in adsorption at the water/air interface, resulting in the low interfacial tension at critical micelle concentration (${\gamma}$$_{CMC}$) and a small molecular area($\omega$), 2) when the hydrophiles of the surfactants are constant, $\omega$’s increase as hydrophobe carbon numbers of the surfactants increase, 3) when the hydrophobes are constant, ${\gamma}$$_{CMC}$’s and $\omega$’s increase as the hydrophile ethylene oxide units increase, indicating effectiveness and efficiency is parallel in this case, 4) the ethylene oxide unit length as a hydrophile has greater influence on u than the hydrophobe chain length.han the hydrophobe chain length.gth.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.495-498
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• 2008

In this paper applicable range of U-Channel Bridge (UCB) that has recently been introduced as a new bridge type was studied. For structural analysis models used with the frame and plate elements was proposed, and verification of the models were performed. Using these structural models structural analysis of models with span length of 20m-45m and inner width of 5m-13m were performed. As a result for U-shape sections were applicable in the range of 20m span and 35m span, slab was applicable in the range of 5m inner width and 12m inner width. To increase applicable range of UCB H-shape sections and slab with rib were proposed. As a result UCB were applicable in the range of 20m span and 45m span, in the range of 5m inner width and 13m inner width.

• Current Research on Agriculture and Life Sciences
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• v.31 no.4
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• pp.280-285
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• 2013

This study supplies basic data to develop a greenhouse model for reducing the damage to single-span greenhouses caused by strong winds and heavy snow. Single-span plastic greenhouses are predominantly used for growing crops in Korea. Thus, the safety wind speeds for single-span greenhouses were calculated and compared with the actual wind speeds and snow depths over a period of 8 years in different regions to analyze the structural safety of single-span greenhouses. The unit wind load and unit snow load were applied to different designs of single-span greenhouse according to the cultivated crop to achieve a structural analysis. As a result, the maximum section force for the wind and snow load was greatest for leaf and root vegetables, where the safety wind speeds for single-span greenhouses according to the cultivated crop were 17.7 m/s(leaf vegetables), 20.2 m/s (fruit vegetables), and 22.3 m/s (root vegetables). Thus, the single-span greenhouses were not found to be safe for the wind load in most regions, except for Hongcheon, Icheon and Sungju. Plus, the safety snow depths for single-span greenhouses according to the crop were 8.8 cm (leaf vegetables), 9.4 cm (fruit vegetables), and 11.8cm (root vegetables). Thus, when comparing the safety snow depths with the actual snow depths, the single-span greenhouses were not found to be safe. Therefore, to improve the safety of single-span greenhouses, the structures need reinforcement by reducing the interval between rafters or increasing the size of the pipes. However, additional research is needed.

• Smart Structures and Systems
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• v.20 no.2
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• pp.197-205
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• 2017

The dynamic performance of railway bridges under high-speed trains draws the attention of bridge engineers. The vibration issue for long-span bridges under high-speed trains is still not well understood due to lack of validations through structural health monitoring (SHM) data. This paper investigates the correlation between bridge acceleration and train speed based on structural dynamics theory and SHM system from three foci. Firstly, the calculated formula of acceleration response under a series of moving load is deduced for the situation that train length is near the length of the bridge span, the correlation between train speed and acceleration amplitude is analyzed. Secondly, the correlation scatterplots of the speed-acceleration is presented and discussed based on the transverse and vertical acceleration response data of Dashengguan Yangtze River Bridge SHM system. Thirdly, the warning indexes of the bridge performance for correlation scatterplots of speed-acceleration are established. The main conclusions are: (1) The resonance between trains and the bridge is unlikely to happen for long-span bridge, but a multimodal correlation curve between train speed and acceleration amplitude exists after the resonance speed; (2) Based on SHM data, multimodal correlation scatterplots of speed-acceleration exist and they have similar trends with the calculated formula; (3) An envelope line of polylines can be used as early warning indicators of the changes of bridge performance due to the changes of slope of envelope line and peak speed of amplitude. This work also gives several suggestions which lay a foundation for the better design, maintenance and long-term monitoring of a long-span high-speed bridge.

• Journal of Pharmaceutical Investigation
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• v.20 no.3
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• pp.129-134
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• 1990

Gelatin microcapsules containing Ftorafur, a hydrophilic anticancer agent, were prepared with congealable disperse-phase emulsification method. The preparation was based on dispersion of ftorafur-gelatin solution with Tween #40 or Span #20 in liquid paraffin. A cationic surfactant, benzethonium chloride, was used to prevent the microcapsules from aggregation. In the case of microcapsules prepared with Tween #40 or Span #20, mean particle size decreased and narrow size distribution was observed. The intrinsic dissolution rate of ftorafur in microcapsules with 1% span #20 was 8.5 times lower than that of intact ftorafur.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.3
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• pp.223-230
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• 2003

Generally, the life-span of a multi-housing complex is over 50 years, but in reality they are usually demolished after 20 years in spite of its remaining life expectancy. Thus, this research focuses on the estimation of the optimum economic life-span of a multi-housing complex. To estimate the minimum total cost point of start to finish of a multi-housing complex, we'll apply MAPI(Machinery and Allied Product Institute) and LCC(Life Cycle Cost) theory.