• Journal of Science Education
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• v.39 no.3
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• pp.446-456
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• 2015

We have analyzed affecting factors of boiling point measurement and proposed to improve these after identifying errors of boiling point experiment in 7th grade science textbooks of 2009 revised curriculum. In the result of analyzing affecting factor of boiling point measurement for nine kinds of science textbooks, we have identified six affecting factors like as types of thermometer, heating instrument, sealing or not of stopper, position of thermometer, shape of container, and volume ratio of material and container. When performing experiment of boiling point measurement, we identified the best results when heating with a hot plate, positioning thermo sensor of MBL near neck branch after filling and sopping 10% volumes of material in round bottom flask. Based on this result, we have compared nine kinds of 7th grade science textbooks and found many errors that must be corrected in most of textbooks. Therefore it should be improved the experiment of science textbooks to enhance the understanding of students and to prevent from misconceptions for boiling point measurement.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.1
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• pp.51-60
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• 1991

The aim of this study is to investigate the heat transfer characteristics in the transient cooling process of a high temperature wall. The slow transient cooling experiment was carried out with a copper block of high thermal capacity. The results of these experiments are as follows. 1. Temperature histories measured by the thermocouple, which is 0.99, 2.00, 2.99mm from the heat transfer surface showed monotonous during the cooling process. These variation are the curves of typical temperature histories in film-boiling, transition-boiling, and nucleate-boiling regions. 2. The temperature histories were measured by thermocouple installed in the copper block. The variations of the surface heat fluxes and surface temperature were computed from the numerical solution method TDMA from the measured temperature histories for radial position one dimensional heat transfer inverse problem. The boiling curves were found by the computed temperature histories. 3. The rewetting point which starts to change from film boiling to nucleate boiling is not connected with the mass velocity and it were found that the temperature of rewetting point indicated about $100^{\circ}C$. 4. The heat flux of rewetting point was about $10^5Kcal/m^2h$, at that time, the heat transfer coeficient indicated about $1000Kcal/m^2h^{\circ}C$ irrelevent to mass velocity. 5. The wall superheat decreases as the pressure increases. But I found that rewetting point appeared under higher condition in the wall temperature.

• Nuclear Engineering and Technology
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• v.48 no.4
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• pp.859-869
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• 2016

Component-scale modeling of boiling is predominantly based on the Eulerian-Eulerian two-fluid approach. Within this framework, wall boiling is accounted for via the Rensselaer Polytechnic Institute (RPI) model and, within this model, the bubble is characterized using three main parameters: departure diameter (D), nucleation site density (N), and departure frequency (f). Typically, the magnitudes of these three parameters are obtained from empirical correlations. However, in recent years, efforts have been directed toward mechanistic modeling of the boiling process. Of the three parameters mentioned above, the departure diameter (D) is least affected by the intrinsic uncertainties of the nucleate boiling process. This feature, along with its prominence within the RPI boiling model, has made it the primary candidate for mechanistic modeling ventures. Mechanistic modeling of D is mostly carried out through solving of force balance equations on the bubble. Forces incorporated in these equations are formulated as functions of the radius of the bubble and have been developed for, and applied to, low-pressure conditions only. Conversely, for high-pressure conditions, no mechanistic information is available regarding the growth rates of bubbles and the forces acting on them. In this study, we use direct numerical simulation coupled with an interface tracking method to simulate bubble growth under high (up to 45 bar) pressure, to obtain the kind of mechanistic information required for an RPI-type approach. In this study, we compare the resulting bubble growth rate curves with predictions made with existing experimental data.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.9
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• pp.605-613
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• 2017

Recently, efficient heat dissipation has become necessary because of the miniaturization of devices, and research on boiling on micro-channels has attracted attention. However, in the case of micro-channels, the friction coefficient and heat transfer characteristics are different from those in macro-channels. This leads to large errors in the micro scale results, when compared to correlations derived from the macro scale. In addition, due to the complexity of the mechanism, the boiling phenomenon in micro-channels cannot be approached only by experimental and theoretical methods. Therefore, numerical methods should be utilized as well, to supplement these methods. However, most numerical studies have been conducted on macro-channels. In this study, we applied the lattice Boltzmann method, proposed as an alternative numerical tool to simulate the boiling phenomenon in the micro-channel, and predicted the bubble growth process in the channel.

• Korean journal of food and cookery science
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• v.33 no.2
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• pp.121-126
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• 2017

Purpose: This study measured the ethyl carbamate (EC) content in commercial and home-made soy sauce and examined the effects of cooking methods, such as boiling and pan-frying, on the EC content. Methods: A total of 20 soy sauce samples including 14 home-made and 6 commercial products were analyzed according to the AOAC official method with some modifications. To simulate conventional boiling, soy sauce containing EC ($14.59{\mu}g/kg$) was heated to $100^{\circ}C$ for four different times: 10, 20, 30, or 40 min. Pan-frying was conducted for 4 min at $170^{\circ}C$. Results: EC was not detected in any of the homemade samples, whereas it was found in the commercial samples, ranging from 2.51 to $14.59{\mu}g/kg$. The concentrations of EC increased gradually with increasing boiling from 14.59 to $26.54{\mu}g/kg$, whereas pan-frying did not affect the EC level in soy sauce. Conclusion: These results indicate that EC is formed by a reaction between the EC precursors during boiling, suggesting that the cooking method of each food should be considered when estimating the dietary exposure to EC.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.1
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• pp.84-94
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• 2010

Physico-chemical analysis and sensory test of loin of lamb were carried out by four different methods such as grilling, pan-frying, oven-roasting and boiling. The crude fat content was all the same at three cooking methods except boiling. The moisture content was not different among grilling, pan-frying and oven-roasting. Hunter's color L-value(lightness) was lowest at grilling method. However, the heating loss appeared greatly at grilling. The hardness of the lamb-loin after cooking showed big differences with the control except boiling treatment. Amino acids in fillet contained highly in the order of glutamic acid > aspartic acid > cystein. The grilling showed a good value not only color of a sensory test but also the appearance. The oven-roasting cooking gave the tenderness and juiciness. The oven-roasting method showed good sensation to overall taste. Therefore, the oven-roasting (at $150^{\circ}C$ for 9 minutes) was suggested as the superior method when the loin of lamb is cooked for reducing off-flavour.

• Journal of Advanced Marine Engineering and Technology
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• v.10 no.2
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• pp.156-164
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• 1986

In the case of boiling on high temperature wall, vapor film covers fully or parcially the surface. This phenomenon, film boiling or transition boiling, is very important in the surface heat treatment of metal, design of cryogenic heat exchanger and emergency cooling of nuclear reactor. Mainly supposed hydraulic-thermal accidents in nuclear reactor are LCCA (Loss of Coolant Accident) and PCM (Power-Cooling Mismatch). Recently, world-wide studies on reflooding of high temperature rod bundles after the occurrence of the above accidents focus attention on wall temperature history and required time in transient cooling process, wall superheat at rewet point, heat flux-wall superheat relationship beyond the transition boiling region, and two-phase flow state near the surface. It is considered that the further systematical study in this field will be in need in spite of the previous results in ref. (2), (3), (4). The paper is the study about the fast transient cooling process following the wall temperature excursion under the CHF (Critical Heat Flux) condition in a forced convective subcooled boiling system. The test section is a vertically arranged concentric annulus of 800 mm long and 10 mm hydraulic diameter. The inner tube, SUS 304 of 400 mm long, 8 mm I.D, and 7 mm O.D., is heated uniformly by the low voltage AC power. The wall temperature measurements were performed at the axial distance from the inlet of the heating tube, z=390 mm. 6 chromel- alumel thermocouples of 76 .mu.m were press fitted to the inner surface of the heating tube periphery. To investigate the heat transfer characteristics during the fast transient cooling process, the outer surface (fluid side) temperature and the surface heat flux are computed from the measured inner surface temperature history by means of a numerical method for inverse problems of transient heat conduction. Present cooling (boiling) curve is sufficiently compared with the previous results.

• Journal of Food Hygiene and Safety
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• v.34 no.6
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• pp.557-561
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• 2019

This study investigated the efficacy of DNA extraction methods for real-time PCR detection of foodborne pathogenic bacteria in livestock manure composts. Livestock manure composts were inoculated with Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes, Bacillus cereus and incubated in enrichment broth. For DNA extraction, enriched samples were treated following boiling method, by chloroform, C₁₈ powder, and proteinase K. As a result, 4 species of bacteria were detected by real-time PCR when subjected to boiling for 30 min and treated with proteinase K. These results suggest that detection of foodborne pathogens by real-time PCR from livestock manure composts could be applicable using effective DNA extraction methodology such as the boiling method or proteinase K.

• Journal of the Korean Chemical Society
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• v.63 no.2
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• pp.123-133
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• 2019

The purpose of this study was to investigate the effect of responsive teaching method for pre-service teachers in Chemistry Education Department of H University. We designed three steps for the discussions: foregrounding the substance of learners' ideas, recognizing the disciplinary connections within learners' ideas, taking up and pursing the substance of thinking. In the step of foregrounding the substance of learners' ideas, we analyzed the questionnaires conducted by the 20 pre-service teachers to understand the nature of their ideas about evaporation and boiling. Among them, five pre-service teachers were selected to recognize the disciplinary connections within learners' ideas. Through these steps, the pre-service teachers have grasped the nature of their thinking about evaporation and boiling, and have experienced the process of modifying or expanding the frames of thought by the disciplinary connections within learners' ideas. In addition, the pre-service teachers directly perceived the effect of the responsive teaching method by experiencing dynamic changes of their conceptions.

• 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.