• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.12
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• pp.1051-1056
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• 2014

After hot rolling, a high-temperature steel plate with a temperature higher than $800^{\circ}C$ is rapidly cooled by multiple circular water jets. In this cooling process, because the temperature of the steel plate is much higher than the boiling point of the cooling water, film-boiling heat transfer occurs and a very thin steam layer forms between the plate surface and the cooling water. The steam layer acts as a thermal resistance that prevents heat transfer between the cooling water and the steel plate. In addition to the film-boiling heat transfer, complex physical phenomena such as the free-surface flow of residual water that accumulated on the material and the material's high-speed motion also occur in the cooling process. In this study, the simultaneous cooling process of the upper and lower sides of a running hot steel strip is investigated using a three-dimensional numerical model and the cooling performances and characteristics of the upper-side cooling and lower-side cooling are compared.

• Journal of Animal Science and Technology
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• v.46 no.3
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• pp.397-404
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• 2004

Turkey thigh meats with skin were ground twice through a 3-mm plate and patties were prepared. Patties were cooked using 5 different methods(oven cooking, pan frying, oil deep frying, boiling, and microwaving) to an internal temperature of 85${\sim}90^{\circ}C$ and packaged in either oxygen permeable PVC zipperbags or oxygen impermeable PVDC bags. The samples were analyzed for thiobarbituric acid reactive substances(TBARS) and cholesterol oxidation products(COPs) after storage at $4^{\circ}C$. The TBARS of cooked meat increased during the storage regardless of cooking methods, vacuum packaged thigh meat produced less TBARS and COPs than the aerobically packaged samples. At the beginning of storage, aerobically packaged meat cooked by boiling method produced higher TBARS than that of others. However, the TBARS of microwaved meat with vacuum packaging increased rapidly after 3 days of storage at $4^{\circ}C$. The amount of total COPs in cooked thigh meat increased linearly with storage time. The level of total COPs in aerobically packaged cooked meat was higher than the vacuum-packaged meat. Microwave produced higher level of total COPs in meat than other cooking methods during storage.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.551-558
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• 2005

The setting and hardening of concrete is accompanied with nonlinear temperature distribution caused by development of hydration heat of cement. Especially at early ages, this nonlinear distribution has a large influence on the crack evolution. As a result, in order to predict the exact temperature history in concrete structures it is required to examine thermal properties of concrete. In this study, the convection heat transfer coefficient which presents thermal transfer between surface of concrete and air, was experimentally investigated with variables such as velocity of wind, curing condition and ambient temperature. At initial stage, the convection heat transfer coefficient is overestimated by the evaporation quantity. So it is essential to modify the thermal equilibrium considered with the boiling effect. From experimental results, the convection heat transfer coefficient was calculated using equations of thermal equilibrium. Finally, the prediction model for equivalent convection heat transfer coefficient including effects of velocity of wind, curing condition, ambient temperature and boiling effects was theoretically proposed. The convection heat transfer coefficient in the proposed model increases with velocity of wind, and its dependance on wind velocity is varied with curing condition. This tendency is due to a combined heat transfer system of conduction through form and convection to air. From comparison with experimental results, the convection heat transfer coefficient by this model was well agreed with those by experimental results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.7 s.250
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• pp.682-691
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• 2006

This study was conducted to assess the effect of mixed fuel composition and mass fraction on spray inner structure in evaporating transient spray under the various ambient conditions. Spray structure and spatial distribution of liquid phase concentration are investigated using a thin laser sheet illumination technique on the multi-component mixed fuels. A pulsed Ar+ laser was used as a light source. The experiments were conducted in a constant volume vessel with optical access. Fuel was injected into the vessel with electronically controlled common rail injector. Used fuel contain $i-octane(C_8H_{18}),\;n-dodecane(C_{12}H_{26})$ and $n-hexadecane(C_{16}H_{34})$ that are selected as low-, middle- and high-boiling point fuel, respectively. Experimental conditions are 25Mpa, 42MPa, 72MPa and 112MPa in injection pressure, $5kg/m^3,\;15kg/m^3\;and\;20kg/m^3$ in ambient gas density, 400K, 500K, 600K and 700K in ambient gas temperature, 300K and 368K in fuel temperature, and different fuel mass fraction. Experimental results indicate that the more high-boiling point component, the longer the liquid phase it were closely related to fuel physical properties, but injection pressure had no effect on. And there was a high correlation between the liquid phase length and boiling temperature at 75% distillation point.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.5 s.236
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• pp.633-642
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• 2005

Nucleate pool boiling experiments for R11 under a constant wall temperature condition were carried out. A microscale heater array was used for the heating and the measurement of high temporal and spatial resolution by the Wheatstone bridge circuit. Very sensitive heat flow rate data were obtained by the control for the surface condition with high time resolution. The measured heat flow rate shows a discernable peak at the initial growth stage and reaches an almost constant value. In the thermal growth region, bubble shows a growth proportional to $t^{\frac{1}{5}}$. The bubble growth behavior is analyzed with a dimensionless parameter to compare with the previous results in the same scale. As the wall superheat increases, the departure diameter and the departure time increase, and the waiting time decreases. But the asymptotic growth rate is not affected by the wall superheat change. The effect of the wall superheat is resolved into the suggested growth equation. Dimensionless parameters of time and bubble radius characterize the thermal growth behavior well, irrespective of wall condition. The comparison between the result of this study and the previous results shows a good agreement at the thermal growth region. The quantitative analysis for the heat transfer mechanism is conducted with the measured heat flow rate behavior and the bubble growth behavior. The required heat flow rate for the volume change of the observed bubble is about twice as much as the instantaneous heat flow rate supplied from the wall.

• Journal of the East Asian Society of Dietary Life
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• v.9 no.4
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• pp.475-482
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• 1999

The effect of boiling with grain vinegar and citric acid on the dissolution of Ca. Mg and P out of beef rib bone during stew preparation was investigated. As the concentration (0, 0.5, 1.0, 2.0%) of grain vinegar and citric acid increased, the amount of Ca, Mg and P dissolved out of the rib bone increased compared with the control. The increase in boiling time(1, 2, 4, 8, 12 hour) also showed the same result. Between the two acid condiments citric acid extracted more Ca, Mg. P compared with the grain vinegar at the same concentration. The pH of the rib bone stew added with the acid condiments increased gradually during the boiling process. In sensory evaluation. the rib bone stew boiled for 12 hours with 2% grain vinegar was highly evaluated compared to the stew prepared with citric acid.

• Journal of the East Asian Society of Dietary Life
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• v.9 no.4
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• pp.483-488
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• 1999

Effect on iron dissolution from iron sauce pans treated with the acetic, malic, citric acid and concentration(0. 0.02. 0.04. 0.1, 0.2, 0.4. 1.0, 2.0, 4.0%) of acidity, boiling times(0, 10. 20, 30, 40, 50, 60mins.) and temperature(5, 20, 40. 60, 80, 10$0^{\circ}C$) of acidity solution and in new and used sauce pans was investigated. As acetic acid concentration increases, iron content has increased. Iron dissolution concentration from iron sauce pan for boiling in malic acid increased more than that of acetic acid and citric acid. At above 6$0^{\circ}C$, as temperature increases, concentration of iron dissolved from iron sauce pan has increased. As boiling time increases, concentration of iron dissolved from iron sauce pan has also increased. Concentration of iron by repeated use has increased. And iron concentration has dissolved in large amount from new pan rather than used pan. Concentration of iron with distilled water by repeated use has increased only slightly. But 1% acetic acid has dissolved in large quantities.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.11-19
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• 2013

An experimental study was conducted to investigate fuel injection characteristics through swirl injectors when the fuel was heated to very high temperature conditions. Three swirl injectors with different orifice diameters and swirler geometries were used to measure the flow coefficient (${\alpha}$) for the injection pressure ranges between 3 and 10 bar and the fuel temperature from 50 to $270^{\circ}C$. The results showed that the variation characteristics of ${\alpha}$ with respect to cavitation number ($K_c$) were highly dependent on both the orifice diameter and the swirler geometry. In addition, the characteristics of ${\alpha}$ variation with respect to AR, the area ratio of the flow through the swirler and the orifice, has revealed that the effect of boiling is retarded but the slope of decreasing ${\alpha}$ after the boiling effect is present tumbles as AR increases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.11
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• pp.906-914
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• 2006

The present paper dealt with an experimental study of boiling heat transfer characteristics of R-290. Pressure gradient and heat transfer coefficient of the refrigerant flow inside horizontal smooth minichannel were obtained with inner tube diameter of 3.0 mm and length of 2,000 mm. The direct electric heating method was applied for supplying a heat to the refrigerant uniformly. The experiments were conducted with R-290 purity of 99.99%, at saturation temperature of 0 to $10^{\circ}C$, a mass flux range of $50{\sim}250kg/m^2s$, and a heat flux range of $5{\sim}20kW/m^2$. The heat transfer coefficients of R-290 increased with increasing mass flux and saturation temperature, wherein the effect of mass flux was higher than that of the saturation temperature. Heat flux has a low effect on the increasing of heat transfer coefficient. The heat transfer coefficient was compared with six existing heat transfer coefficient correlations. The Zhang et al.'s correlation (2004) gave the best prediction of heat transfer coefficient. A new correlation to predict the two-phase flow heat transfer coefficient was developed based on the Chen correlation. The new correlation predicted the experimental data well with a mean deviation of 11.78% and average deviation of -0.07%.

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.27-27
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• 2003