• 한국세라믹학회지
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• 제28권9호
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• pp.712-720
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• 1991

The effect of cyclic compressive stress on fracture responses of Al2O3 was investigated under uniaxial stress cycling. Experimental data were obtained for Al2O3 tension specimens under uniaxial tension-unloading and tension-compression cyclic loading conditions. To investigate the effect of compressive stress on the crack growth, theoretical results from the crack growth rate were compared with measured stress vs. failure relations. At low stress level in tension-compression cycling, residual tensile strains were also observed about failure time.

• Journal of Advanced Marine Engineering and Technology
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• 제29권6호
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• pp.701-706
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• 2005

Pipes, tubes. and tubular sections with external transverse high fins have been used extensively for heating cooling, and degumidifying air and other gases. This work was performed to investigate an air side heat transfer charactieristics of minichannel with tension wound transverse fin. This estimate was confirmed conversion heat capacity the air side surface area enlargement and heat transfer charactieristics performed available inlet tube side hot water mass flux or outlet tube side air frontal air velocity. The most suitable tension wound transverse finned minichannel was measured extremely low in air side pressure drop and fin effectiveness $3.3\~4.4$. The pressure drop $0.9\~2.8Pa$ was ranged frontal air velocity $0.5\~1.2m/s$. It is also appeared that heat transfer in air side could be better conversion heat area which has been increased $330\%$ of heat capacity compared with the bare tube.

• Journal of Chest Surgery
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• 제44권3호
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• pp.253-256
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• 2011

Spontaneous pneumothorax is a common clinical problem in emergency care. However, the overall incidences of primary spontaneous pneumothorax has been reported from as low as 1.4% to 7.6%. The clinical findings of simultaneous bilateral spontaneous pneumothorax can be variable. Clinical presentation is variable, ranging from mild dyspnea to tension pneumothorax. Bilateral tension pneumothorax can defined as cases where no tracheal deviation is detected in chest X-ray, and symptoms may be equal bilaterally. Herein, we present a case with simultaneous bilateral tension pneumothorax, severely deteriorated (i.e. with loss of consciousness, cyanosis, and hemodynamically unstable), that was successfully treated with immediate large-size needle decompression.

• 한국응용과학기술학회지
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• 제27권3호
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• pp.240-248
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• 2010

The blending effects of surfactants on the polystyrene emulsion polymerization were studied. The blending of Triton X-100 and SDS affects to the interfacial properties of the styrene monomer and water phases, and finally, the properties of the polystyrene latex particles. As the blending ratio of SDS/Triton X-100 increases, the interfacial tension and CMC of the blended surfactants were decreased and results in a reducing the size of the latex particles. It was found that the interfacial tension was reduced when the surfactant were blended. By increasing the SDS content, the interfacial tension was reduced, and, at a certain condition, the interfacial tension was reached to an extremely low value to form micro-emulsion and the nano-sized latex particles (80~110 nm).

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.2809-2818
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• 2022

In this investigation work, liquid-liquid extraction (L.L.E) through three distinctive frameworks have been examined for assurance of slip velocity (S.V), and characteristic velocity (C.V) in a non-center rotating column (N.C.R.C) with a wide extend of factors. Three double frameworks with distinctive interfacial tension comprising of toluene-water (high interfacial tension), n-butyl acetate-water (medium interfacial tension), and n-butanol-water (low interfacial tension) were investigated for tests. Two common relationships for the expectation of S.V and C.V, including phase stream rates, rotor speed, column geometry additionally physical properties, are displayed. The recommended relationships were compared with test information gotten from the writing and the display examination. Findings of this study, the present proposed correlations are more accurate than those previously reported.

• 펄프종이기술
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• 제43권5호
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• pp.49-54
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• 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.

• Journal of Advanced Marine Engineering and Technology
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• 제22권2호
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• pp.139-145
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• 1998

Filament winding method is widely used for composite fabrications using low viscosity liquid for-mation and processing asymmetrical structures of pressure vessel pipe rocket motor case etc. The filament winding method is affected by several parameters such as pot life of process time viscosi-ty of resin filament winding temperature and schedules curing condition and post curing condi-tion of resin. To develope high functional composite materials the rotation(5, 15, 20, 30rpm) of the winding machine was controlled by D.C motor. And the wiper to give proper tension was equipped between strand and resin bath. The resin is hooked by the design wiper. The adequate cure schedule was found by DSC. NOL ring test is carried out to investigate the basic physical properties such as design technology. The void contents in filament winding is generally higher than that of the prepreg laminated plate. These high contents of void can make a crack in resin in spite of low deformation. These problem was solved by giving tension in processing. To improve the characteristics of fiber volume fraction void contents resin/fiber bonding the winding speedc is changed under constant tension. It was found that resin impregnation was not different from in fiber contents void contents at the range of 0.5~1kg tension but it was found that resin was not impregnated at the above of 1.5kg tension. In burst test a pure PE liner was failed at a nozzle part under the $14kg/\textrm{cm}^2$ pressure but a pressure vessel of CNG was failed at a cylinder part under the $200kg/\textrm{cm}^2$ pressure.

• 수산해양기술연구
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• 제22권2호
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• pp.40-45
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• 1986

In this paper, the I-resistance curve of low-carbon steel with 3 mm thickness was investigated for various crack ratios. The experiments were carried out for the center cracked tension (CCT) specimen with about 50 mm width on an instron machine. The plane stress fracture toughness obtained by the Simpson's formula was Ii. = 24.96 kgffmm. Simpson's formula which considers crack growth in obtaining J integral showed more conservative lin than Rice's and Sumpter's. For materials that may be approximated by the Ramberg and Osgood stress strain law, the relevant crack parameters like the J integral, load line displacement are approximately normalized. Crack driving forces in terms of the I integral are computed for low-carbon steel CCT specimen using the above estimation scheme. Comparison of the prediction with actual experimental measurements by Simpson's formula showed good agreement for several different sized specimen.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권6호
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• pp.46-55
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• 2016

This experimental study was aimed to estimate interfacial tension of brine-$CO_2$ by using a pendant bubble method and image analysis. Measurements were performed for wide ranges of temperatures, pressures, and salinities covering reservoir conditions in Pohang basin, a possible candidate for $CO_2$ storage operation in Korea. The profiles of $CO_2$ bubbles in brine obtained from image analysis with the densities of brine and $CO_2$ from previous studies were applied to Laplace-Young equation for calculating interfacial twnsion in brine-$CO_2$ system. The experimental results reveals that the interfacial tension is significantly affected by reservoir conditions such as pressure, temperature and water salinity. For conditions of constant temperature and water salinity, the interfacial tension decreases as pressure increases for low pressures (P < $P_c$), and approaches to a constant value for high pressures. For conditions of constant pressure and water salinity, the interfacial tension increases as temperature increases for T < $T_c$, with an asymptotic trend towards a constant value for high temperatures. For conditions of constant pressure and temperature, the interfacial tension increases with increasing water salinity. The trends in changes of interfacial tension can be explained by the effects of the reservoir conditions on the density difference of brine and $CO_2$, and the solubility of $CO_2$ in brine. The information on interfacial tensions obtained from this research can be applied in predicting the migration and distribution of injecting and residual fluids in brine-$CO_2$-rock systems in deep geological environments during geological $CO_2$ sequestrations.

• 한국자동차공학회논문집
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• 제25권2호
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• pp.133-139
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• 2017

The timing chain system, which is a typical power transmission technology applied to a vehicle, has been widely used by the automotive industry because it is normally designed to last a car's lifetime. However, the timing chain system may cause some problems due to the shape of the chains and the polygonal behavior on contact between the chain and the sprocket. In addition, noise and vibration caused by transmission error are the most typical problems encountered by major automotive manufacturers and they are considered as the main source of customer complaint. The initial tension of the chain-sprocket system is thought to be the main cause of transmission error, and it is regarded as the source of engine vibration and noise. The initial tension of the chain system should be controlled carefully since a low initial tension can cause twisting, which may lead to a system malfunction, while a high initial tension can reduce the service life due to a worn down contact surface. In this paper, the kinematic analysis model is generated with various initial tensions, which are controlled by changing the shape of the fixed guide with the largest contact surface with chain. The results showed that the transmission error was minimized on a particular range of initial tension, and the tendency showed that the error changed with a higher sensitivity at a lower initial tension.