• The Korean Journal of Food And Nutrition
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• v.35 no.4
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• pp.239-246
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• 2022

In this study, the dietary fiber content of 33 kinds of agricultural products and seaweeds was compared with that of raw products after heat treatment. To verify the total dietary fiber analysis method, the recovery rate was reviewed by measuring the total dietary fiber content for 4 standard certified substances. As a result, the recovery rate of the analysis value for the true value was 98.8%~103.1%, which was judged to be reliable. The total dietary fiber of vegetables ranged between 0.61~5.36 g/100 g for raw vegetables and 0.55~4.84 g/100 g for heat-treated vegetables. Among the 24 kinds of vegetables used in the analanalysis, the total dietary fiber content of heat-treated Korean radish (3.13 g/100 g) was the highest compared to that of raw radish (0.61 g/100 g). The total dietary fiber of beans was between 13.86~29.69 g/100 g for raw beans and 6.72~18.40 g/100 g for heat-treated beans. In particular, the total dietary fiber content of sword beans was the highest in both raw (29.69 g/100 g) and boiled (18.40 g/100 g) beans. The total dietary fiber content of the three types of seaweed was 1.93~4.85 g/100 g in raw seaweed and 0.99~5.72 g/100 g in heat-treated seaweed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.10
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• pp.3293-3303
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• 1996

Numerical analyses have been performed to estimate the absorption heat and mass transfer coefficients in absorption process of the LiBr aqueous solution and the total heat and mass transfer rates in a vertical tube absorber which is coolING ed by air. Axisymmetric cylindrical coordinate system was adopted to model the circular tube and the transport equations were solved by the finite volume method. Absorption behaviors of heat and mass transfer were analyzed through falling film of the LiBr aqueous solution contacted by water vapor in tube. Effects of film Reynolds number on heat and mass transfer coefficients have been also investigated. Especially, effects of tube diameter have been considered to observe the total heat and mass transfer rates through falling film along the tube. Based on the analysis it has been found that the total mass transfer rate increases rapidly in a region with low film Reynolds number(10 ~ 40) as the film Reynolds number increases, while decreases beyond that region. The total heat and mass transfer rates increase with increasing the tube diameter.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.121-128
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• 2012

Improvement in the energy efficiency has been studied of the desiccant cooling system by applying a vapor compression type heat pump to modify the system into a hybrid system. The cycle simulation was performed and the results were compared between a reference desiccant cooling system composed of a desiccant rotor, a sensible rotor and a regenerative evaporative cooler, and a hybrid desiccant cooling system with the sensible rotor being replaced by a heat pump. Though the electric consumption increases as much as the compressor power consumption, the total cooling capacity increases and the thermal energy input decreases by the addition of the heat pump. Therefore, the total energy efficiency can be improved if the increase in the electric consumption can be compensated with the increase in the cooling capacity and the decrease in the thermal energy input. The results showed that the total energy efficiency is optimized at a certain heat pump capacity. When the heat from the CHP plant is used for the thermal energy input, the energy consumption of the hybrid system is reduced by 20~30% compared with the reference system when the heat pump shares 30~40% of the total cooling capacity.

• International Journal of Air-Conditioning and Refrigeration
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• v.7
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• pp.55-68
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• 1999

In this study, computer simulation programs were developed for single-stage, two-stage, and three-stage condensation heat pumps and their performance with CFC11, HCFC123, HCFC141b was examined under the same external conditions. The results showed that the coefficient of performance(COP) of an optimized 'non-split type' three-stage condensation heat pump is 25-42% higher than that of a conventional single-stage heat pump. The increase in COP, however, differed among the fluids tested. The improvement in COP is largely due to the decrease in average LMTDs in condensers, which results in the decrease in thermodynamic irreversibility in heat exchange process. For the three-stage heat pump, the highest COP is achieved when the total condenser area is evenly distributed among the three condensers. For the two-stage heat pump, however, the optimum distribution of the total condenser area varies with an individual working fluid. For the three-stage system, 'splitting the condenser cooling water'for the use of intermediate and high pressure subcoolers helps increase the COP further. When the individual cooling water entering the intermediate and high pressure subcoolers is roughly 10% of the total condenser cooling water, the maximum COP is achieved showing roughly an 11% increase in COP as compared to that of the 'non-split type' heat pump.

• Journal of the Korean Society of Safety
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• v.32 no.5
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• pp.20-24
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• 2017

In this study, we have performed the Cone Calorimeter test in accordance with ISO 5660-1 to check the combustion characteristics of building flooring materials. The fire risk of these materials were evaluated by construction code, KFI criteria and standards of flame retardant performance. When samples exposed to external heat flux, all samples consumed a lot of Oxygen for a long time. So heat release from sample burning continued so long. And also all samples produced so much smoke. Even though a few samples were satisfied with only peak heat release rate criteria, all 8 samples were not satisfied with criteria of peak heat release rate and total heat released together. The results of 5 min total heat released were $15.9MJ/m^2{\sim}5.9MJ/m^2$. It menas the results are more than 2~6 times higher than the criteria. The results of 10 min total heat released were $30.1MJ/m^2{\sim}100.8MJ/m^2$. It means the results are more than 3~12 times higher than the criteria. 6 of 8 samples were not satisfied with Dm.corr.(corrected maximum smoke density) criteria. The building flooring materials which we used for this test ignited very fast and the burning continued so long. It means these samples are susceptible to fire.

• KIEAE Journal
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• v.15 no.2
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• pp.117-122
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• 2015

Purpose: Generally, 30% of the total energy consumption in office building is used for artificial indoor lightings, and almost 75-85% of electric power in fluorescent and Light-Emitting Diode (LED) lightings can be dissipated as a form of heat into indoor environment. The heat generated by indoor lightings can cause the increase of cooling load in office buildings. Thus, it its important to consider indoor lightings as a heat and light source, simultaneously. Method: In this study, we installed two kinds of indoor lightings including fluorescent and LED lightings and measured surface temperature of both indoor lightings. In addition, we obtained ambient temperature of indoor space and finally calculated total heat dissipated from plenum area and surface of lightings. Result: Total indoor heat gain was 87.17Wh and 201.36Wh in cases of six 40W-LED lightings and 64W-fluorescent lightings, respectively.

• Journal of the Korean Society for Heat Treatment
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• v.19 no.3
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• pp.141-148
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• 2006

An experimental study is presented for water droplet impingement on a steel surface in the process of heat treatment. The objective of the present work is to examine characteristic of evaporation cooling due to surface roughness and droplet diameter under conductive heat input condition. The surface temperatures varied from $80{\sim}155^{\circ}C$, surface roughness was from $R_a=0.12{\mu}m$ to $R_a=1.14{\mu}m$ and droplet diameter was from 2.4 mm to 3.0 mm. The results show that the total evaporation time is shorter for the larger surface roughness and the smaller droplet size, the time average heat flux has maximum value for the larger surface roughness and the smaller droplet size. The total evaporation time has not influence on the nuclear boiling region.

• Korean Journal of Food Science and Technology
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• v.52 no.5
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• pp.503-509
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• 2020

The present study investigated the effects of dry and moist heat treatments on total phenols, total anthocyanins, and antioxidant activity levels in black chokeberry (Aronia melanocarpa) fruits. Lyophilized chokeberry powder samples were heated in a drying oven at 60, 100, 160, 180, and 200℃ for 20, 40, or 60 min. Finely ground fresh chokeberry fruits were heated in water at 60, 80, and 100℃ for 20 min, and bioactive compound and antioxidant activity levels were measured. The bioactive compounds and antioxidant activity decreased with increasing temperature and treatment duration. Antioxidant activity was preserved at 160℃ or lower without significant loss for dry heating, whereas moist heat treatment increased both bioactive compounds and antioxidant activity with increasing temperature.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.175-180
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• 2003

An inverse problem to determine two-dimensional total heat exchange factor is studied for the prediction of the billet temperature in the reheating furnace. Temperature measurements by the experiment are used in the inverse analysis. This inverse analysis employs the conjugate gradient method. The total heat exchange factors for 12-zones of the cross-section of the billet are estimated. The estimated temperatures at measurement locations are in good agreements with the measured temperatures.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.16 no.4
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• pp.31-38
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• 2020

The investment in the technology of using a combined heat source is insufficient, which utilizes the advantages of various heat sources to maximize the potential energy and at the same time increases the performance of the heat pump. In this study, as basic data for the development of a high-efficiency hybrid heat pump system that actively connects and uses various heat sources, simulations were conducted for the heat pumps in two cases where geothermal and hydrothermal heat were applied respectively. In May, COP increased by about 27.3% compared to geothermal heat. In February, the COP percentage decrease of hydrothermal heat compared to geothermal heat is -6.9%. In May, total energy consumption can be reduced by 21.1% when hydrothermal is applied compared to geothermal heat. In February, the total energy consumption increases by 3.4%.