• Journal of the Korea Institute of Military Science and Technology
• /
• v.13 no.6
• /
• pp.1034-1042
• /
• 2010

This study investigates effects of three different parameterizations of vertical mixing scheme on upper ocean simulation of the East Sea, focusing on the seasonal variations of the sea surface temperature(SST) and the mixed layer depth(MLD) using an ocean general circulation model(GFDL MOM1.1). The considered vertical mixing schemes are the Laplacian scheme(L scheme) that use a constant eddy coefficient, the Mellor-Yamada scheme(MY scheme), and a new scheme(Noh scheme). The Noh scheme, a second-order turbulence closure, was developed considering recent observational evidences such as the enhancement of turbulent kinetic energy near the sea surface. During summer L scheme underestimates the SST, while MY scheme overestimates the SST, compared to climatological SST. Noh scheme produces the SST in better agreement with climatological one. During winter all schemes overestimate the SST up to $4^{\circ}C$ compared to climatological SST. Vertical profiles of the basin-mean temperature show that L scheme produces higher temperature below the thermocline than those of other schemes. The winter MLD simulated from L scheme is rather large compared to that from other schemes, but the differences in MLD during summer are not significant.

• Journal of the Korean Solar Energy Society
• /
• v.39 no.1
• /
• pp.33-40
• /
• 2019

Al-doped ZnO (AZO) thin films were synthesized on Si(100) wafers via plasma enhanced metal organic chemical vapor deposition (PE-MOCVD) method using diethyl zinc (DEZ) and N-methylpyrrolidine alane (MPA) as precursors. Effects of Al/Zn mixing ratio, plasma power on the surface morphology, crystal structure, and electrical property were investigated with SEM, XRD and 4-point probe measurement respectively. Growth rate of the film decreased slightly with increasing the Al/Zn mixing ratio, however electrical property was enhanced and resistivity of the film decreased greatly about 2 orders from $9.5{\times}10^{-1}$ to $8.0{\times}10^{-3}{\Omega}cm$ when the Al/Zn mixing ratio varied from 0 to 9 mol%. XRD analysis showed that the grain size increased with increasing the Al/Zn mixing ratio. Growth rate and electrical property were enhanced in a mild plasma condition. Resistivity of AZO film decreased down to $7.0{\times}10^{-4}{\Omega}cm$ at an indirect plasma of 100 W condition which was enough value to use for the transparent conducting oxide (TCO) material.

• Tribology and Lubricants
• /
• v.17 no.2
• /
• pp.130-137
• /
• 2001

In this paper, the thermal effects on the performance of floating ring journal bearing are investigated theoretically. The numerical analyses include pressure drop at inner film due to a centrifugal force, fluid momentum effects of supply oil into inner film and thermal effects in lubricating films. All performance data are presented as the rotating speed of journal from 10,000 rpm to 70,000 rpm.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.03a
• /
• pp.48-54
• /
• 2004

The effects of injector spacing s and injector diameter d on mixing are numerically investigated in supersonic combustor with perpendicular injection behind a backward-facing step. Simulations are reported for airstream Mach number of 2.4. Parameters are changed on following 4 cases to investigate the effects of injector configuration on mixing efficiency $\eta_m$. In the case of varying d or s, dynamic pressure ratio $Rq(=(pu^2)_j/(pu^2)_a)$ is also varied to keep bulk equivalence ratio $\Phi({\oe})Rq.d^2/s)$ constant. (l) Injector spacing s is varied at constant $\Phi$=0.5, 1, 2 for injector diameter d=6mm. In the case of $\Phi$=1, $\eta_m$ has its maximum value at s=24mm. The reason is that increase of $\eta_m$. , by widening spacing at Rq=constant competes with decrease of $\eta_m$ by increasing Rq at s=constant. When spacing is narrow, the flow field of vicinity of injector becomes two-dimensional because adjacent jets interferes each other. By widening spacing, air is easily entrained by three-dimensional effect. This mechanism also appears in the case of $\Phi$=0.5, 2 for d=6mm, and $\eta_m$. reaches its maximum value at s=24mm for $\Phi$=0.5 and at s=42mm for $\Phi$=2. (2) In the case of injector diameter d varied at $\Phi$=1 for s=30mm, $\eta_m$. has its maximum value at d=3mm. The reason is that decrease of $\eta_m$ by increasing injector diameter competes with increase of $\eta_m$ by decreasing Rq at d=constant.(3) In the case of s varied at $\Phi$=0.5, 1,2 for d=3mm, the injector spacing at which mixing efficiency has its maximum value is s= 18mm for $\Phi$=0.5, s=24mm for $\Phi$=1, s=24mm for $\Phi$=2. Therefore it is found that d=3mm and s=24mm can be optimum configuration over a range of $\Phi$=0.5~2.(4) The effect of h on the optimum spacing is investigated. s is varied for d=6mm at step height h=4, 6, 8mm. The simulation results do not show significant change on the step height.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.43 no.1
• /
• pp.50-55
• /
• 2023

The present study investigated the effects of forage cutting and baler mixing on the chemical compositions, fermentation indices, and aerobic stability of whole crop rice (WCR) haylage. The WCR ("Youngwoo") was harvested at 48.4% dry matter and ensiled into a 300 kg bale silo with forage cutting (whole crop without cutting vs. 5 cm of cutting length). The WCR forages were ensiled without baler mixing process (CON) or with (MIX). The concentrations of dry matter, crude protein, ether extract, crude ash, neutral detergent fiber, and acid detergent fiber of whole crop rice before ensiling were 48.4, 9.70, 2.57, 6.11, 41.2, and 23.5%, respectively. The forage cutting did not affect the chemical compositions, fermentation indices, microbes, and aerobic stability of WCR haylage (p>0.05). The CON haylages tend to be higher in NDF content (p<0.10). The MIX haylages had lower in lactate (p=0.019), and lactate:acetate ratio (p<0.001). The MIX haylages had higher in lactic acid bacteria (LAB) (p=0.010). Therefore, this study concluded that the fermentation quality of WCR haylage improved by baler mixing, but had no effects by forage cutting.

• Journal of the Korean Geotechnical Society
• /
• v.34 no.10
• /
• pp.5-16
• /
• 2018

The ever-increasing amount of waste vinyl is causing big environmental problems. In particular, those from farming industry are sometimes left on site or even illegally reclaimed due to the lack of environmental concerns and capacity for collection, which worsens the situation. It is, therefore, believed that the recycling of waste vinyl is the most ideal solution in the viewpoint of environmental preservation. In this context, the potential of vinyl strip as a ground reinforcing material is investigated to expand the application of waste vinyl recycling. In this study, a series of uniaxial compression tests and resonant column tests were performed for sand specimens reinforced with vinyl strips and cement to investigate their reinforcing effects on static and dynamic behaviors. The changes in the uniaxial compressive strength (UCS), the shear modulus and the damping ratio according to the mixing ratio of vinyl strips and cements were analysed for sand specimens, having 40% and 60% relative densities, under various mixing conditions. As a result, both the static and dynamic reinforcing effects of vinyl strip-cement mixture were confirmed and the optimum mixing ratio was proposed.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.6B
• /
• pp.623-631
• /
• 2006

A new model, the periodic transient storage zone model, is developed to describe solute transport mixing in natural streams and rivers with various bottom boundaries. To assess the effects of storage zones structure on transient storage exchange, we analyze data from salt and dye injection experiments in a recirculating laboratory flume with four spatially periodic pool-riffle sequences characteristic of natural river systems under low flow conditions. Dye injections show that solute transport mixing controlled by surface shapes of both the bed and the side in channels. As no existing transient storage model could represent these effects, we developed a new axially periodic transient storage zone model that better represent the effects of channel characteristics in natural river systems. The new model is also fitted to data from salt tracer injection experiments in four reaches of the upper Sabin River, Texas, USA. The proposed model is in good agreement with the field experimental data.

• Clean Technology
• /
• v.18 no.4
• /
• pp.404-409
• /
• 2012

In this study, the effects of mixing intensity and coagulant dosages on the characteristics of floc growth for phosphorus removal were investigated. The experiments were conducted under Al/P molar ratio of 1.0, 1.5 and 2.0; rapid mixing intensity with G value of 100, 300, and 500 $s^{-1}$. The characteristics of floc growth were measured by flocculation index (FSI) and the removal efficiencies of phosphorus by using different size filters. The removal efficiencies of soluble phosphorus increased as Al/P molar ratio and rapid mixing intensity increased. However, the highest removal efficiencies of T-P were observed at G value of 300 $s^{-1}$. When Al/P molar ratio was lower than 1.0, the value of FSI at G value of 500 $s^{-1}$ was the largest. However, when Al/P ratio was larger than 1.0, the value of FSI at G value 300 $s^{-1}$ was the largest. Effects of mixing intensity and Al/P molar ratio on coagulation for phosphorus removal of synthetic and real wastewater effluent were observed to be similar.

• Korean journal of food and cookery science
• /
• v.20 no.2
• /
• pp.119-125
• /
• 2004

Effects of various chemical additives and heat treatments were investigated on the wheat flour doughs and breads. Ammonium ferric citrate, Ca-citrate, CaCl$_2$, FeSO$_4$, MgCl$_2$and ZnO were mixed respectively to the flour up to 0.1% of flour dry weight basis. Ammonium ferric citrate and ferric sulfate showed no significant effects on the dough properties and magnesium sulfate, calcium chloride and zinc oxide increased elastic properties and optimum dough mixing time. However, calcium citrate and magnesium chloride showed no significant effects on the dough mixing properties. Most of chemicals were detrimental on the bread volume except MgSO$_4$ and CaCl$_2$. Breads with MgSO$_4$ and CaCl$_2$ retained the equal or slightly higher volume compared to control bread. Crumb and crust colors of breads with addition of chemicals were changed to lighter than that of control bread. L values both of crumb and crust increased with addition of chemicals except Ca-citrate. To inactivate the endogenous enzymes of flour, flour was roasted under electric oven, exposed to UV and microwave. Those heat treatments of flour increased dough stability and produced no dough breakdown after optimum mixing time. However, bread volume of heat-treated flour decreased.

• Journal of the korean Society of Automotive Engineers
• /
• v.13 no.1
• /
• pp.66-74
• /
• 1991

A multidimensional numerical simulation of turbulent combustion in a constant volume bomb is implemented to clarify the effects of swirl on combustion. This simulation includes the ICED-ALE numerical technique, the skew-upwind differencing scheme, the modified .Kappa.-.epsilon. turbulence model, and the combustion model of the Arrhenius type and the turbulence-mixing-control type. The calculations of the turbulent combustion with swirl are carried out. It shows that the results agree with the measurements allowably. Therefore, the effects of swirl on turbulent combustion are examined through the parametric study of swirl.