• Journal of the Korean Chemical Society
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• v.45 no.5
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• pp.481-490
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• 2001

The purpose of this study was to find out the problems on the fractional distillation experiments in the middle school science textbooks based on the 6th curriculum and to suggest an efficient experiment method for the middle school students. The first step was the classification of the experiments in 8 science textbooks according to heating apparatus and liquid mixtures. The second step was doing each experiment 3 times followed by the experimental process in the textbooks. The third step was developing the alternative experiments for solving the problems found in the second step. The heating method used in the alternative experiments were direct heating, oil bath, and heating mantle. The results of the second step showed that the direct heating experiment of branched round flask was more close to the theoretical prediction than the experiment of water bath heating of branched test tube. Also the direct heating experiment of thermally insulated branched round flask was better than the result of the experiment which was not insulated. The results of the third step showed that the experiment using heating mantle regulated heating power by observing the temperature of distillate gave the closest result to the theoretical prediction. From the above results, it is concluded that the experiment using branched test-tube with water bath heating is not adequate for the fractional distillation and an alternative experiment using insulated branched round flask with heating mantle regulated heating power during experiment is recommended.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.3
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• pp.330-341
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• 1999

An experimental study for the two types of burners used in the non-oxidizing direct fired furnaces of the heat treatment process for the cold rolled plate has been carried out to investigate the combustion characteristics and the oxidization of the surface of steel plate. A steep temperature gradient and entrainment of residual oxygen were found near the heating surface in the flame of the nozzle mixing burner which has strong swirl velocity component. It was concluded that the elimination of the residual oxygen and the increase of the temperature of combustion gas on the heating surface are needed to enhance the performance of the burners for application to the non-oxidizing direct fired furnaces.

• Carbon letters
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• v.15 no.1
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• pp.15-24
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• 2014

As a part of the electromagnetic spectrum, microwaves heat materials fast and efficiently via direct energy transfer, while conventional heating methods rely on conduction and convection. To date, the use of microwave heating in the research of carbon-based materials has been mainly limited to liquid solutions. However, more rapid and efficient heating is possible in electron-rich solid materials, because the target materials absorb the energy of microwaves effectively and exclusively. Carbon-based solid materials are suitable for microwave-heating due to the delocalized pi electrons from sp2-hybridized carbon networks. In this perspective review, research on the microwave heating of carbon-based solid materials is extensively investigated. This review includes basic theories of microwave heating, and applications in carbon nanotubes, graphite and other carbon-based materials. Finally, priority issues are discussed for the advanced use of microwave heating, which have been poorly understood so far: heating mechanism, temperature control, and penetration depth.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.73-74
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• 2007

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1433-1438
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• 2007

Characteristics of a phase change type micro actuator have been studied. The micro actuator has been designed for a micro-pump in an active direct methanol fuel cell(DMFC), consisting of an actuating chamber, a membrane, an electric heater, and a sensor of resistance temperature detector (RTD). In the present study, researches have been focused on the response of the actuator to control algorithm of the heater. The experiments demonstrated that the displacement of the membrane increase with temperature variation which is a function of applied voltage, duty ratio, and operating frequency of heating. The results also showed that operation of the actuator with high voltage at small duty of heating is more efficient than the same power consumption of heating with low voltage at large duty.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.83-88
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• 2004

Micro wires manufactured by the straightening progress are widely used in bio-medical and semi-conductor fields. In this study, we have developed a novel straightener which uses the direct heating method for straightening. In order to avoid the surface oxidization, during the heating process, we supplied the inert gas(Ar) and examined the effect of the gas flow rate. The effect of the tension and the current applied to the tungsten micro wires were thoroughly studied. From various experiments, it was found that when the tension is $500{\sim}600gf$ and the current is about 1.5A, we obtained higher straightness(${\approx}1{\mu}m/1000{\mu}m$) and roundness ($<{\pm}2{\mu}m/100{\mu}m$).

• Nuclear Engineering and Technology
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• v.33 no.5
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• pp.468-482
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• 2001

As a process of Direct Containment Heating (DCH) issue resolution for Korean Standard Nuclear Power Plants (KSNPs), a containment load/strength assessment with two different approaches, the probabilistic and the deterministic, was performed with all plant-specific and phenomena-specific data. In case of the probabilistic approach, the framework developed to support the Zion DCH study, Two-Cell Equilibrium (TCE) coupled with Latin Hypercubic Sampling (LHS), provided a very efficient tool to resolve DCH issue. In case of the deterministic approach, the evaluation methodology using the sophisticated mechanistic computer code, CONTAIN 2.0 was developed, based on findings from DCH-related experiments or analyses. For three bounding scenarios designated as Scenarios V, Va, and VI, the calculation results of TCE/LHS and CONTAIN 2.0 with the conservatism or typical estimation for uncertain parameters, showed that the containment failure resulted from DCH loads was not likely to occur. To verify that these two approaches might be conservative , the containment loads resulting from typical high-pressure accident scenarios (SBO and SBLOCA) for KSNPs were also predicted. The CONTAIN 2.0 calculations with boundary and initial conditions from the MAAP4 predictions, including the sensitivity calculations for DCH phenomenological parameters, have confirmed that the predicted containment pressure and temperature were much below those from these two approaches, and, therefore, DCH issue for KSNPS might be not a problem.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.6
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• pp.288-291
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• 2002

We developed a new RF indirect-heating LPE furnace. The thermal gradient of our newly developed furnace is less than that of direct heating, and is as gentle as that of the resistance-heating LPE furnace. With this new furnace, the heating and/or cooling is faster than that of the resistance-heating furnace. Impurity-doped YIG film was grown from a $PbO-B_{2}O_{3}$, based flux on a (111) GGG substrate. To study the effect of the impurities on the MSSW threshold power and the saturation response time, we used two microstrip lines to excite and propagate the MSSW at 1.9 GHz. The MSSW threshold power and saturation response time was found to be related to the $\Delta$H.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.1
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• pp.97-104
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• 1987

An analysis on the thermodynamic optimum use of thermal water has been accomplished. The systems investigated are power generation and space heating. The space heating systems considered in this study are direct heating, heat pumps and heat pump assisted heating. The object of this study is to find the optimum selection and operation of the system under the given resources. The measure of such optimum conditions is the EFFECTIVENESS, the concept of efficiency based upon the Second Law of Thermodynamics. The temperature of water to waste is identified as the most important parameter to be optimized. The analysis indicates that for high temperature resources (higher than about 425K) power generation yields the best performance and is therefore recommended. The heat pumps are recommended for the resource temperature less than about 327K. The heat pump assisted heating system shows its superiority for the very narrow temperature range (320K-330K) and thus the use of this system should be considered when the flow rate is very limited. thus the direct heating is appropriate for the temperature range of 330K-425K. The analysis also shows the optimum capacity of thermal water, which may be useful for the initial estimation of heating or power generation potentials of given resources.

• Korean Journal of Food Science and Technology
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• v.22 no.5
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• pp.575-581
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• 1990

The existence of the equivalent point for a thermal processing system was demonstrated using arbitrarily chosen ideal direct heating curves. i.e. isothermal heating curves at $120^{\circ}C$ for 10min and at $135^{\circ}C$ for 10sec. Under these conditions, G-values and F-values were calculated at various values of Ea- and z-values by applying the Arrhenius and the Bigelow models respectively. The equivalent time and equivalent temperature were determined by both line intersection and linear regression methods. The equivalent points estimated by both the line intersection and the linear regression methods were consistent and their values were the same as the heating time and temperature of the ideal direct heating curves.