• Journal of the Korean Society of Mechanical Technology
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• v.13 no.3
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• pp.81-85
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• 2011

The night time electric cost is cheaper due to electric supply and demand policy in Korea from 1985. Currently about 900,000 customers are using night time electric heating boilers and this causes shift of peak demand time to night in winter and increase of deficit spending. To solve this problem, replacing night time electric heating boiler by air-source heat pump using night time electricity has been proposed. An air-source heat pump can provide efficient heating equipment especially in a warm climate. For estimating the night time electric heat pump COP(Coefficient of Performance), Korean Standard KS C 9306:2010 and European Standard EN-14511:2004 is available. SCOP(Seasonal COP) using European weather bin data is also calculated. SCOP is not available yet but European Committee for Standardization will establish a standard in the near future. The evaluation result show that the replacing night time electric heating boiler by heat pump can be possible.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.2
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• pp.173-181
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• 1994

A Cold spot temperature control system for the batch annealing furnace has been estabilished in order to reduce energy consumption to improve productivity and stabilize the propertics of products. Therefore we confirmed a relation between annealing cycle time and atmospheric gas, variation of coil cold spot temperature with time during heating and actual temperature measurements at mid-width of each coil during heating and actual temperature measurements at mid-width of each coil during soaking. The results of the tempaeature variation effect on the batch annealing are as follows. 1) Heating time is reduced to one half with increasing atmospheric gas flow rate and changing of atmospheric gas component from HNx to Ax gas, and annealing cycle time is reduced to 2.7 times. 2) In case of short time healing, the slowest heating part is the center of B coil, in case of long time heating, the low temperature point moves from the center of coil to inside coil. And the temperature in this part is higher than other parts when cooling. When finished heating, the cold spot is located 1/3 of coil inside in case of HNx atmospheric gas. But center of coil in case of Ax atmospheric gas. 3) The outside of top coil is the highest temperature point when heating, which becomes the lowest temperature point when cooling. So, this point becomes high temperature zone at heating and low temperature zone at cooling, It has relation according to atmospheric gas component and flow rate. 4) Soaking time at batch annealing cycle determination is made a decision by the input coil width, and soaking time for quality homogenization of 1214mm width coil must be 2.5 hours longer than that of 914mm width coil for the same ciol weight. 5) Annealing cycle time with Ax atmospheric gas is extended 1 hour in of slow cooling during 5 hours in order to avoid rapid cooling.

• 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.

• Fisheries and Aquatic Sciences
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• v.25 no.1
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• pp.31-39
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• 2022

To clarify the factors influencing the physical properties of fish after heat treatments, we investigated changes in the properties of proteins in the dorsal ordinary and dark muscle of yellowtail (Seriola quinqueradiata) heated under different conditions commonly used for the purposes of food hygiene. High-temperature/short-time heating (85℃ for 90 s and 75℃ for 60 s) affected the protein solubility more than low-temperature/long-time heating (63℃ for 30 min). Sodium dodecyl sulphate-polyacrylamide gel electrophoresis and differential scanning calorimetry showed that low-temperature/long-time heating reduced the degree of actin denaturation in fish compared with that by other heating conditions. In addition, collagen solubility was enhanced with low-temperature/long-time heating. Therefore, these results suggest that differences in the degree of actin and collagen denaturation are responsible for the enhanced meat tenderness and diminished meat shrinkage, resulting from low-temperature/long-time heating.

• Korean journal of food and cookery science
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• v.2 no.2
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• pp.8-15
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• 1986

This study was carried out to investigate changes of the lipid contents and the fatty acid composition in shank during heating time and frozen storage. 1. The total lipid contents of raw shank were about 3.57% and decreased stepwise during heating time 30, 60, 90 min and frozen storage(24hrs) The contents of neutral lipid, glycolipid and phospholipid were 70.71%, 6.36%, and 22.93% in raw shank, and neutral lipid contents were decreased, whereas Phospholipid contents were increased according to heating tide. In frozen storage, neutral lipid and glycolipid contents were increased, while phospholipid contents were decreased. 2. Lipids of shank possessed about 8 kinds of fatty acid as the constituent by gas-liquid chromatography analysis. The main fatty acids were oleic acid, palmitic acistearic acid and linoleic acid: the fatty acids of total lipids in raw shank were 43.48% of oleic acid, 23.13% of palmitic acid,12.00% of stearic acid and 6.75% of linoleic acid. Also the fatty acids were 43.32% of oleic acid, 23.26% of palmitic acid, 9.30% of stearic acid 2.15% of linoleic acid in neutral lipid, 22.63% of oleic acid, 8.44% of palmitic acid, 11.98% of stearic acid, 27.01% of linoleic acidin glycolipid, 39.38% of oleic acid, 15.89% of palmitic acid, 15.55% of stearic acid, 17.49% of linoleic acid in phospholipid. 3. The fatty acid pattern of total lipid, neutral lipid, glycolipid and phospholipid was not any changes, whereas there was a difference in the fatty acid contents: palmitic acid and stearic acid of total lipid were decreased in the 30 min and 60 min heating but increased in 90min heating, and linoleic acid of neutral lipid was increased stepwise during heating time and frozen storage. Also palmiict acid of glycolipid was increased gradually and linoleic acid in heating time 30, 60 min was higher than 90 min and frozen storage. Among fatty acids in phoapholipid, oleic acid was increased during heating time, while decreased in frozen storage, and linoleic acid was not any change but linolanic acid was increased. UFA/SFA of phospholipid was the highest when heating time was 60 min. From above results, it was found that when heating time was 60 min beneficial nutritionally, comparing with changes of fatty acid composition according to the heating time aid frozen storage.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.2
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• pp.203-210
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• 2013

In this study, cod bone were used as the main ingredient of a stock that can be eaten with Korean dried noodles. The stock was produced with heating for 30, 40, 50, 60, or 70 minutes using high-pressure extraction methods. Moisture content, chromaticity, pH, sugar content, salinity, mineral contents, quantitative analysis, and overall acceptance were studied to determine the optimal heating time. In our result, S1 the showed highest water contents 98.10%, while S5 showed the lowest moisture content (97.47%). There were no significant difference in pH between samples, while salinity and sugar content increased with increases in heating time. In terms of mineral contents, sodium and potassium showed proportional difference with increases in heating time, however, magnesium, calcium, and iron did not change. The results from a quantitative analysis test showed that transparency, fishy smell, delicate flavor, savory flavor, salt taste, and umami taste became stronger with increases in heating time increase. From the above results, the overall taste of the stock increases with increases in high-pressure heating time. Specifically, S4 high-pressure heating scored the highest on appearance, flavor, taste, after-taste, and overall acceptance. Thus, 60 minutes of high-pressure heating time is most desirable when producing stock with cod bones as a main ingredient.

• KIEAE Journal
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• v.7 no.5
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• pp.81-86
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• 2007

The research analyzes the arrangement of boiler and hot water header, the method of radiator pipe setting, hot water supply control, hourly heating situation of each room for underfloor radiant heating systems in Korea and suggests an alternative to improve to efficient heating method. One of the best options for install position of hot water distributor is under kitchen sink which is center point of all rooms, according to previous research of the energy saving strategies. When the radiator pipes are arranged to each individual room instead of bedrooms through livingroom and kitchen, it has energy saving effects. For rooms without occupancy according to a time period, hot water supply method should be intermittent heating rather than continuous heating. For this intermittent heating method, individual control of hot water supply is more practical, and it can lead to massive energy savings. The intermittent heating system has time-lag, so it is more effective in energy saving with mild and comfort condition if the spaces are preheated by automatic control equipment prior to required time.

• Journal of Welding and Joining
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• v.8 no.4
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• pp.20-26
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• 1990

In this study, to make research on its optimum condition in friction weld when the heating pressure is change during 1.6 to 3.0 $kgf/mm^2$, the experiment was performed with metal bearing under various condition; 1600 r.p.m spindile speed, 0.6 $kgf/mm^2$ preheating pressure, upset pressure 2.6 $kgf/mm^2$, 0.5 seconds preheating time, 1.7 seconds heating time, water and air was ejected 6 $kgf/mm^2$ into the bushing. On the basis of the experimental results, the following conclusion are drawn; 1) At the area of weld interface, the heardness is shown the maximum value and heat-affected zone about 0.5mm both sides. 2) Bending strength is shown the optimum heating pressure 2.4 kgf/mm. 3) With the approach of the flash, Sn is increased only 2 mm in A-alloy structure.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.5
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• pp.1227-1234
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• 1994

A cold spot temperature control system for the batch annealing furnace has been established in order to reduce energy consumption which is essential to improve productivity and stabilize the properties of products. A relationship between annealing cycle time and gas flow rate is developed and also for the variation of coil cold spot temperature with time during heating, and actual temperature measurements at mid-width of each coil during soaking. The results of the temperature variation effect on the cold rolled steel sheet batch annealing are as follows. (1) Cooling rate increasing gradually with increasing atmospheric gas flow, but heating rate is hardly increasing without atmospheric gas component change. (2) In case of short time heating, the slowest heating part is the center of B coil and in case of ling time heating, the low temperature point moves from the center of coil to inside coil. (3) The outside of top coil is the highest temperature point under heating, which becomes the lowest temperature point under cooling. (4) Soaking time determination depends on the input coil width, and soaking time for quality homogenization of 1214 mm width coil must be 2 hours longer than that of 914 mm width coil.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.4
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• pp.64-69
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• 2011

Magnesium alloy has been known as lightweight material in automobile and electronic industry with aluminum alloy, titanium alloy and plastic material. Friction welding is useful to join different kinds of metals and nonferrous metals they are difficult to be joined by such as gas welding, resistance welding and electronic beam welding. In this study, friction welding was performed to investigate optimization process of Mg alloy with a 20mm diameter solid bar. For that, the orthogonal array $(L_{9}(3^{4}))$ was used that contained four factors and each factor had three levels. Control factors were heating pressure, heating time, upsetting pressure and upsetting time. Also tensile tests were carried out to measure mechanical properties for welded conditions. The levels of heating pressure and upsetting pressure used were 15, 25, 35MPa, and 30, 50, 70MPa, respectively. In addition those of heating time and upsetting time were 0.5, 1, 1.5 sec and 3, 4, 5 sec., respectively, rotating speed of 2000rpm. From the experimental results, optimization condition was estimated as follows; heating pressure=35MPa, upsetting pressure=70MPa, heating time=1.5sec, upsetting time=3sec.