• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.461-464
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• 2008

This study is compactability and Passing ability to get to know the flowing characteristic of high flowing self-compacting concrete with mixing steel fiber of various size and diameter. After flowing test, size and diameter are getting longer, flowing performance is getting lower. It meets the standard of combined high flowing self-compacting concrete of JSCE 2 grade and passing performance from ASTM C 1621. Through this study, it can be possible to be applied in site of HSCC with mixing steel fiber.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.2
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• pp.265-272
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• 1996

In this paper, attitude computation algorithm for a strap down ARS(Attitude Reference System)of an underwater vehicle has been studied. Attitude errors o the ARS using low-level gyroscopes tend to increase with time due to gyroscope errors. To cope with this problem, a mixing algorithm of accelerometer aided attitude computation has been developed. The algorithm can successfully bound the error increase for cruising motion, but it gives instantaneously large errors when a vehicle maneuvers. To improve the performance in case of vehicle's maneuver, a new attitude computation mixing algorithm complying state of vehicle and to manage the adjustment of the gains which are invariant in the existing algorithm. In addition, a gain scheduling method is applied to fuzzy inference composition process for real-time computation. Monte Carlo simulation results show that the proposed algorithm provides better performance than the existing algorithm.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.8
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• pp.946-952
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• 2005

The $CO_{2}$ refrigeration cycle is expected to reduce the compressor work and increase the COP by applying two-phase ejector as a device for the recovery of dissipated expansion energy. In this study, the performance of the cycle was simulated and effects of the ejector shapes on the performance of the $CO_{2}$ refrigeration cycle were investigated. The following results were obtained through the cycle simulation. The COP of the $CO_{2}$ refrigeration cycle with two-phase ejector flow which expansion is occured in the isentropic manner is increased by a maximum of 24 $\%$ than the basic cycle with expansion valve If the velocity nonequilibrium in the mixing process is assumed the COP of the cycle is increased with the increase of the length and the decrease of the section area of the mixing tube. The best cycle performance is obtained when the divergent angle of diffuser is 7.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.73-76
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• 2005

This study aims to suggest a simple and convenient design for a mix proportion method for high performance concrete by determining the optimum fine aggregate ratio and minimum binder content based on the maximum density theory. The mix design method introduced in this study adopted the optimum fine aggregate ratio with a minimum void and binder content higher than the minimum binder content level. The research results reveal that the method helps to reduce trial and error in the mixing process and is a convenient way of producing high performance concrete with self filler ability. In an experiment based on the mix proportion method, when aggregate with the fine aggregation ratio of 41$\%$ was used, the minimum binder content of high performance concrete was 470kg/$m^{3}$ and maximum aggregate capacity was $0.657m^{3}/m^{3}$. In addition, in mixing high performance concrete, the optimal slump flow to meet filler ability was 65$\pm$5cm, V load flow speed ranged from 0.5 to 1.5.

• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.3
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• pp.100-106
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• 2009

As an effort to prevent environmental problems caused by ozone depletion and global warming, alternative refrigerants are being developed, and one of the candidates is carbon dioxide. To overcome slightly low efficiency of $CO_2$ refrigeration system, air-conditioning cycle using an ejector was suggested. Ejector compensates throttling loss in an expansion device by reducing compression work. In this study, the ejector refrigeration cycle using $CO_2$ as a refrigerant is investigated to understand the effect of the mixing section diameter and refrigerant charge amount on the performance. If mixing section diameter is too large or too small, either cases show low performance. The optimum refrigerant charge amount which gives the best performance is found for standard operating conditions. The air-conditioning cycle was analyzed for several operating conditions.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.4
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• pp.21-28
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• 2014

In this study, evaluated ware the strength and durability of the vegetated water purification channel concrete to which recycled aggregates, hawang-toh and jute were applied. Box-Behnken method of response surface analysis in statistics was applied to the experimental design. Experimental variables are as follows, recycled coarse aggregates, hawang-toh, blast-furnace slag and jute fiber. In the experiment, conducted were the tests of compressive strength, chloride ion penetration, abrasion resistance and impact resistance the replacement rate effects of the recycled aggregates, blast-furnace slag and hwang-toh on the performance of vegetated water purification channel concrete were analyzed by using the response surface analysis method on the basis of the experimental results. In addition, an optimum mixing ratio of vegetated water purification channel concrete was determined by using the experimental results. The optimum mixing ratio was determined to be in 10.0% recycled coarse aggregates, 60.0% blast-furnace slag, 10.1% hwang-toh and 0.16% jute fiber. The compressive strength, chloride ion penetration, abrasion rate, and impact number of fracture test results of the optimum mixing ratio were 24.1 MPa, 999 coulombs, 10.30 g/mm3, and 20 number, respectively.

• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.3
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• pp.150-156
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• 2007

In this paper, we studied security systems for information security of several systems that use in network environment along with information society. Therefore, we designed symmetry style base mixing style cryptographic system that apply block and stream way to solve problems of complexity and lower processing speed etc. Symmetry style base mixing style cryptographic system including authentication operation holds performance that the processing speed and the calculation amount are more superior than asymmetry style. Result that design system by Synopsys 1999.10 and ALTERA MaxPlus 10.1 and do simulation, mixing style password system that we propose is that information security offers very efficient assistance and performance in necessary field in network environment.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.520-524
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• 2000

A ejector system is one of the fluid machinery, which has been mainly used as an exhaust pump or a vacuum pump. The ejector system has often been pointed out to have only a limited efficiency because it is driven by pure shear action and the mixing action between primary and secondary streams. In the present work, numerical simulations were conducted to investigate the effects of the geometry and the mass flow ratio of supersonic ejector-diffuser systems on their mixing performance. A fully implicit finite volume scheme was applied to solve the axisymmetric Navier-Stokes equations, and the standard ${\kappa}-{\varepsilon}$ turbulence model was used to close the governing equations. The flow fields of the supersonic ejector-diffuser systems were investigated by changing the ejector throat area ratio and the mass flow ratio. The existence of the second throat strongly affected the shock wave structure inside the mixing tube as well as the spreading of the under-expanded jet discharging from the primary nozzle, and served to enhance the mixing performance.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.1
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• pp.27-38
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• 2014

Flow mixing and pressure drop characteristics for marine selective catalytic reduction applications were investigated numerically to develop an efficient static mixer. Two different mixers, line- and swirl-type, were considered. The effect of vane angles on the relative intensity, uniformity index, and pressure drop was investigated in a swirl-type mixer; these parameters are dramatically affected by the mixer geometry. The presence of a mixer, regardless of the mixer type, led to an improvement of approximately 20% in the mixing performance behind the mixer in comparison to not having a mixer. In particular, there was a tradeoff relationship between the uniformity and the pressure drop. Considering the mixing performance and the pressure drop, the swirl-type mixer was more suitable than the line-type mixer in this study.

• Journal of the Korean Ceramic Society
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• v.42 no.4
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• pp.276-281
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• 2005

$LiNi_{1-y}M_{y}O_{2}(M=Zn^{2+},\;Al^{3+},\;and\;Ti^{4+},\;0.000\{\le}y{\le}0.100)$ were synthesized by the combustion method by calcining in $O_{2}$ stream at $750^{\circ}C$ for 36 h. XRD analyses, observation by FE-SEM and measurement of the variation of discharge capacity with the number of cycles were carried out. The composition $LiNi_{0.99}M_{0.01}O_{2}(M=Zn^{2+},\;Al^{3+},\;and\;Ti^{4+})$ of all the compositions showed relatively good electrochemical properties. $LiNi_{0.99}M_{0.01}O_{2}$ exhibited poor crystallinity and $LiNi_{0.99}M_{0.01}O_{2}$ showed the cation mixing of large fraction. $LiNi_{0.99}M_{0.01}O_{2}$ with improved cycling performance showed good crystallinity and the cation mixing of small fraction.