• Journal of Advanced Marine Engineering and Technology
• /
• v.18 no.5
• /
• pp.12-23
• /
• 1994

The two-phase flow is observed in power plants, chemical process plants, and refrigeration systems etc., and it is very important to solve the heat transfer mechanism of a boiler, an automic reactor, a condenser and various types of evaporators. Recently, the problem of two phase heat transfer is braught up in many regions with development of energy saving technique. In flow boiling system it is necessary to store data in each condition because the heat transfer characteristics of flow boiling region vary by the change of flow pattern and the magnetude of heat flux to tube length, and be subtly affected by the flow and heating condition. So basic study for knowing flow pattern in heat transfer region and the relation between heat transfer characteristic and flow condition is desired to accumulate data in wide variety of liquid and flow system in the study of heat transfer of two phase flow. In this study R-113 was selected as working fluid whose properties were programmed by least square method, and experiment was conducted in the region of mass flow $1.628{\times}10^6$~$4.884{\times}10^6$/kg/$m^2$hr with inlet subcooling 10~3$0^{\circ}C$, sustaining test section inlet pressure to 1.5kg$_f$/$cm^2$abs.

• Korean Journal of Food Science and Technology
• /
• v.6 no.2
• /
• pp.70-74
• /
• 1974

The round muscle of Korean cattle and squid muscle were cooked with various methods which were followed digestibility test by use of pepsin in-vitro, determination of amino nitrogen in the course of digestion procedure by using Formol method (AOAC) and influence of ether treatment for preminary test also examined. The results obtained were summarized as follows: 1. The order of digestibility values were demonstrated as follows: In case of beef, it was autoclaving, frying, raw, freezing, roasting, boiling and in case of squid muscle, it was raw, autoclaving, boiling, freezing, dry heating and roasting. 2. The amounts of amino nitrogen for beef and squid muscle were increased in proportion to digestibility value. 3. There were no significances in the digestibility between treating with ether and none of any treatment of beef and squid muscle in raw condition.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.25 no.2
• /
• pp.101-108
• /
• 2013

This paper is presented an experimental study of flow boiling heat transfer characteristics of ammonia, and is focused on pressure gradient and heat transfer coefficient of the refrigerant flow inside horizontal small tube with inner diameter of 3.0 mm and length of 2000 mm. The direct heating method is applied for supplying heat to the refrigerant, where the test tube is uniformly heated by electric current. The local heat transfer coefficients were obtained over a heat flux range of 20 to $80kW/m^2$, a mass flux range of 50 to $500kg/m^2s$, a saturation temperature range of 0 to $10^{\circ}C$, and quality up to 1.0. The pressure drops increase with increasing mass flux and heat flux, and with decreasing saturation temperature. The heat transfer coefficients increase with increasing mass flux and saturation temperature in middle and high quality region. And the local heat transfer coefficient increase with increasing heat flux in low quality region. The heat transfer coefficient of the experimental result was compared with six existing heat transfer coefficient correlation. A new boiling heat transfer coefficient correlation based on the superposition model for ammonia in small tubes is developed average deviation of -0.17% and mean deviation of 10.85%.

• Nuclear Engineering and Technology
• /
• v.31 no.6
• /
• pp.572-585
• /
• 1999

The characteristics of two-phase flow instability in a vertical boiling channel connecting with an unheated riser are investigated through the linear stability analysis model. Various two-phase flow models, including thermal non-equilibrium effects, are taken into account for establishing a physical model in the time domain. A classical approach to the frequency response method is adopted for the stability analysis by employing the D-partition method. The adequacy of the linear model is verified by evaluating experimental data at high quality conditions. It reveals that the flow-pattern-dependent drift velocity model enhances the prediction accuracy while the homogeneous equilibrium model shows the most conservative predictions. The characteristics of density wave oscillations under low-power and low-quality conditions are investigated by devising a simple model which accounts for the gravitational and frictional pressure losses along the channel. The necessary conditions for the occurrences of type-I instability and flow excursion are deduced from the one-dimensional D-partition analysis. The parametric effects of some design variables on low quality oscillations are also investigated.

• Korean Journal of Pharmacognosy
• /
• v.42 no.1
• /
• pp.82-88
• /
• 2011

This study was carried out to investigate the optimum conditions for extraction of soluble acidic polysaccharides from ginseng marc. Method of carbazole-sulfuric acid was applied to determine the amount of acidic polysaccharides in ginseng marc. The amounts of soluble acidic polysaccharides in water extract of ginseng marc were increased with increasing extraction temperature. The contents of acidic polysaccharides were not significantly different despite the extraction time increasing from 0.5 hours to 6 hours. To estimate the rehydration rate of the freeze dried polysaccharide, the extracted acidic polysaccharide fraction powder was determined the amount of soluble acidic polysaccharides by carbazole-sulfuric acid method again. The rehydration rate of acidic polysaccharides from water-extract of red ginseng marc at room temperature was 100%. On the other hand, the rehydration rate of acidic polysaccharide of red ginseng marc at boiling temperature was about 50%. The rehydration rate of acidic polysaccharides from water-extract of white ginseng marc at room temperature was 50%. The rehydration rate of acidic polysaccharide of red ginseng marc at boiling temperature was about 40%. The rate of soluble acidic polysaccharide of Red Ginseng is higher than that of White Ginseng. We can find out the maximum extraction method of soluble acidic polysaccharide from ginseng marc.

• Journal of the Korean Society of Food Culture
• /
• v.30 no.6
• /
• pp.736-749
• /
• 2015

The present study addresses the tea utensils and tea drinking methods seen in tomb mural paintings of Song, Liao, Jin, and Yuan, which were Koryo's foreign exchange countries. The paintings illustrate the pointing tea method, which was popular during dynasty times. Tea utensils observed in the paintings include a tea mill, mill stone, and tea pestle necessary for making cake tea into powder. The tea stove and boiling bottle are depicted as being required to boil water. Some mural works vividly depict how a tea drinker pours hot water from a boiling bottle into a cup with a stand, mixes it with a tea spoon, and whisks tea powder for foaming with a tea whisk. The tea drinking method of the Southern race Han is also similarly described in the tomb mural paintings of Liao, Jin, and Yuan from Northern nomads. The distribution of tea culture had an enormous influence on the development of tea utensil manufacturing methods. The significance of this study is that these findings can be used as basic data to provide food culture insights into Koryo celadon tea utensils.

• Journal of Sericultural and Entomological Science
• /
• v.13 no.1
• /
• pp.73-78
• /
• 1971

The purpose of this study is to find out the method of conditioned weight test by which the dealing weight of raw silk can be calculated from true fiber in order to do the fair trading. The results of this study were as follows. 1. It is more reasonable than the current test that conditioned weight as a dealing weigh can be calculated by boil-off and moisture regain which is a percentage of boil-on and moisture regain to net weight. Because the boil-off and moisture regain can show directly the amount of true fiber and reproductibility in raw silk. In this study the boil-off and moisture regain is to take dry weight after boiling-off from net weight. 2. To calculate the conditioned weight from boil-of and moisture regain it would be proper that the standard additional ratio is 44 per cent of dry weight after boiling-off. 3. Boil-of percent of the sizing sample skein used in the size test did not show a statistical significance comparing with the boil-off percent of sample skeins (24 skeins) which may represent that of a lot. To observe this result boil-off percent of the sizing sample skein may represent that of a lot. 4. In Korea if conditioned weight test substitute for test of boil-off and moisture regain, we make a profit of two billion won in a year at the current market-price.

• Korean Journal of Food Science and Technology
• /
• v.50 no.1
• /
• pp.8-13
• /
• 2018

The textural and antioxidant properties, as well as the changes in functional constituents of shiitake mushrooms cooked by three different methods (boiling, steaming, and frying) were analyzed. The hardness of the mushrooms did not change significantly at the end time of cooking for each method. The antioxidant properties determined by measuring the free-radical scavenging activity and total phenolic content were the highest in the control (uncooked shiitake), and these properties were adversely affected after cooking, especially by boiling. Both the riboflavin and eritadenine contents were the highest in the control, but decreased upon cooking, in the following order: frying > steaming > boiling. The ergocalciferol content after frying was less than that in other samples. Although uncooked shiitake mushroom showed a higher concentration of functional constituents, it needs to be cooked adequately owing to its tough texture. If the hardness of the mushrooms cooked by different methods is the same, frying is considered the most acceptable method.

• Food Science of Animal Resources
• /
• v.43 no.5
• /
• pp.767-791
• /
• 2023

To evaluate the effect of different cooking methods on the physicochemical quality and volatile organic compounds (VOC) of dairy beef round, twelve beef round pieces were divided into four groups: raw, boiling, microwave, and sous-vide. The sous-vide group had a higher pH than the boiling or microwave groups. The boiling group exhibited the highest shear force and CIE L^*, followed by the microwave and sous-vide groups (p<0.05). The sous-vide group received higher taste and tenderness scores from panelists (p<0.05) and showed significantly higher levels of aspartic and glutamic acids than the other groups. The sous-vide and microwave groups had the highest oleic acid and polyunsaturated fatty acid levels, respectively. The sous-vide group had significantly higher hypoxanthine and inosine levels than the other groups. However, the microwave group had higher inosine monophosphate levels than the other groups. The sous-vide group had a higher alcohol content, including 1-octen-3-ol, than the other groups. Octanal and nonanal were the most abundant aldehydes in all groups. (R)-(-)-14-methyl-8-hexadecyn-1-ol, p-cresol, and 1-tridecyne were used to distinguish the VOC for each group in the multivariate analysis. Sous-vide could be effective in increasing meat tenderness as well as taste-related free amino acid (aspartic acid and glutamic acid) and fatty acid (oleic acid) levels. Furthermore, specific VOC, including 1-octen-3-ol, 2-ethylhexanal ethylene glycol acetal, and 2-octen-1-ol, (E)-, could be potential markers for distinguishing sous-vide from other cooking methods. Further studies are required to understand the mechanisms underlying the predominant association of these VOC with the sous-vide cooking method.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.31 no.9
• /
• pp.764-771
• /
• 2007

The objective of the present work is to evaluate the evaporation heat flux of deposited droplet on the hot surface by using of inverse heat transfer technique. On the basis of measured temperature, a integral form solution is determined for the transient temperatures beyond the two positions by using Green's function technique. This method first approximates the temperature data with a half polynomial series of time. we compared this result with constant radius model in single phase regime, nucleate boiling regime, film boiling regime respectively. this paper performed the experiments as following conditions: (a)the surface temperature is within the range between $80^{\circ}C\;and\;160^{\circ}C$ in the conduction, (b) droplet diameter are 2.4 and 3.0mm. (c) surface roughness is $0.18{\mu}m$.