• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.6
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• pp.784-794
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• 1998

The present study has been directed at developing thermal models to investigate the dynamic behavior of a solar cooling system including an absorption chiller, solar collectors, a hot water storage tank, a fan coil unit, and the air-conditioned space. The operation of the system was simulated for 8 hours in two different operation modes. In the mode 1, the system operated without any capacity control.0 the mode 2, an auxiliary boiler supplied heat to the generator if hot water temperature became lower than a certain value. Moreover, the mass flow rate of hot water to the generator was controlled by comparing the instantaneous room air temperature with the design value. The variation of temperature and concentration in the system components and that of heat transfer rates in the system were obtained for both modes of operation. It was found that the room temperature was maintained near the desired value in the mode 2 by supplying auxiliary heat or controlling the mass flow rate of hot water, while the deviation of room temperature was quite great in the mode 2.

• The Korean Journal of Food And Nutrition
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• v.17 no.3
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• pp.246-253
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• 2004

This study was carried out to examine softening stability, exponent of Avrami equation, color change, sensory characteristcs during storage when hydrocolloid was added to the sea tangle paste treated with acetic acid and heat treatment. Rate constant of solidification showed the least value of 0.05 in Avrami equation. In addition hardness of the softened sea tangle paste was not changed after two days of storage in case of carrageenan. Rate of hardness in the softened sea tangle paste formulated with carrageenan exhibited the lowest value of 0.28 kg/mm/day. Heat melting spreadability of the softened sea tangle paste showed the highest value in case of carrageenan and its fluid behavior was rheopectic. Viscosity change in the sea tangle paste formulated with carrageenan was the least during storage and its significant difference at the level of p < 0.05 was exhibited. Change of L, a and b value of softened sea tangle formulated with carrageenan during storage was significantly different at level of p<0.05. Color preference, odor, cohesiveness, softerness, process compatibility and overall acceptance of softened sea tangle were revealed to be in best when carrageenan was added. When hydrocolloid was added to the softened sea tangle paste, it showed the positive result in quality and storage stability of softened sea tangle paste. It was extremely effective on softening stability when carrageenan was added to the softened sea tangle paste.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1461-1467
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• 2009

The electric railway is a clean and energy saving system, because it requires relatively less energy than automobiles by transporting the same passengers or goods. Six thousands of vehicles are operated on Korean urban transit system. This system is 95% of regeneration system. Especially, the VVVF-Inverter vehicle has a merit of the highest regeneration rate. Energy consumption is 90% for traction and 10% for auxiliary supply. Braking energy is about 40% of energy consumption. Up to 40% of the tractive power of vehicles capable of returning energy to the power supply can be regenerated during braking and that this energy can be used to feed vehicles which are accelerating at the same time. The energy generated by braking vehicle would simply be converted into waste heat by its braking resistors if no other vehicle is accelerating at exactly the same time. Such synchronized braking and accelerating can not be coordinated, the ESS(energy storage system) stores the energy generated during braking and discharges it again when a vehicle accelerates. This paper presents field tests about the energy saving rate of the developed ESS. when the ESS is on/off, energy saving rate of the ESS is tested. The verification test in the field focused on energy saving.

• Horticultural Science & Technology
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• v.30 no.5
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• pp.527-533
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• 2012

This study was carried out to investigate the effects of aminoethoxyvinylglycine (AVG) application and heat treatment on fruit quality of 'Fuji' apples during CA storage. AVG ($75mg{\cdot}L^{-1}$) was applied to 'Fuji' tree at 150 and 175 days after full bloom (DAFB) and the fruit were harvested at 185, 195, and 205 DAFB, respectively. Respiration rate and ethylene production of fruit applied with AVG were greatly reduced more than those in control. Flesh firmness and acidity of fruit applied with AVG were higher than those in control. Flesh browning occurred in all of the control fruit regardless of harvest date. However, AVG-treated fruits were free of flesh browning except for late harvested fruits. At 185 DAFB, 'Fuji' apples were harvested and prestorage heat treatment was done for 3 days at $38^{\circ}C$ and 6 hours at $46^{\circ}C$. Heat treatment at $38^{\circ}C$ and $46^{\circ}C$ prior to CA storage greatly reduced respiration rate and ethylene production. The incidence of flesh browning were 35%, 14%, and 5%, in control fruit, heating at $38^{\circ}C$ and $46^{\circ}C$, respectively. The titratable acidity was lower at heated apple than at controlled one.

• Journal of Hydrogen and New Energy
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• v.27 no.6
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• pp.642-650
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• 2016

One of the most feasible solution for reducing the excessive energy consumption and carbon dioxide emission is usage of more efficient fuel such as hydrogen. As is well known, there are three viable technologies for storing hydrogen fuel: compressed gas, metal hydride absorption, and cryogenic liquid. In these technologies, the storage for liquid hydrogen has better energy density by weight than other storage methods. However, the cryogenic liquid storage has a significant disadvantage of boiling losses. That is, high performance of thermal insulation systems must be studied for reducing the boiling losses. This paper presents an experimental study on the effective thermal conductivities of the composite layered insulation with aerogel blankets($Cryogel^{(R)}$ Z and $Pyrogel^{(R)}$ XT-E) and Multi-layer insulation(MLI). The aerogel blankets are known as high porous materials and the good insulators within a soft vacuum range($10^{-3}{\sim}1$ Torr). Also, MLI is known as the best insulator within a high vacuum range(<$10^{-6}{\sim}10^{-3}$ Torr). A vertical axial cryogenic experimental apparatus was designed to investigate the thermal performance of the composite layered insulators under cryogenic conditions as well as consist of a cold mass tank, a heat absorber, annular vacuum space, and an insulators space. The composite insulators were laminated in the insulator space that height was 50 mm. In this study, the effective thermal conductivities of the materials were evaluated by measuring boil-off rate of liquid nitrogen and liquid argon in the cold mass tank.

• Solar Energy
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• v.11 no.3
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• pp.44-52
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• 1991

The benefits of thermal stratification in sensible heat storage systems has been considered and studying by several investigators. In this paper, the basic data which is hard to obtain normally through the experiment were obtainable through the computer simulation. The major objectives of the study were to assess the benefits of stratified storage in residential solar water heating application and to suggest the optimum design parameters. From the computer simulation, following results were obtained. 1. The solar load fraction increases with increasing the number of tank segments. In these simulation, the magnitude of the improvement was about 10%. 2. The solar load fraction increases when the ratio of diameter to height of the tank(H/D) increases to 3, but H/D exceed 3 then, the solar load fraction decreases. In these simulation, the magnitude of the improvement was about 3%. 3. Increasing the collector flow rate slightly improved the performance of the mixed storage system(Node=1). But, for the stratified storage system(Node=N), the solar load fraction increases with decreasing flow rate until the point is reached at which the collector outlet temperature reaches the boiloff limit of $100^{\circ}C$ over some portion of the simulation period.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.9
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• pp.361-366
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• 2016

As an alternative of well-mixed storage tank with lower coil only, we have proposed a tank with lower and upper coils and verified a superior thermal stratification in a tank, which results in increased collector efficiency and solar fraction. But the phenomenon of temperature reversal was often experimentally observed in the tank, so a revised control was successfully applied which is to heat only lower coil using three way valve if temperature reversal occurs and to operate the collector with low flow rate when the condition of solar radiation is not good. In the present study, using TRNSYS we compared the existing lower heating and the proposed lower and upper heating with a control preventing temperature reversal. The results showed that the proposed method has an increase of collector efficiency by 5.1% and solar fraction by 3.2%.

• Asian-Australasian Journal of Animal Sciences
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• v.7 no.2
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• pp.179-182
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• 1994

A study was conducted using four dairy heifers to determine the effect of 10, 20 and $30^{\circ}C$ environmental temperatures on the physiological responses and heat production, at a fixed level of TDN intake ($60.5\;g/kg^{0.75}\;d$). The analysis showed significant affects of environmental temperature on respiration rate (RR), mean body temperature (Tb), changes in body heat storage (S) and heat production (HP). The HP at $20^{\circ}C$ was almost the same as at $10^{\circ}C$, but the HP at $30^{\circ}C$ was 11% higher than at $10^{\circ}C$. A tendency for an elongation of standing time (ST) with the increase in environmental temperature was also observed. These results suggest that the increase in energy cost of elongation of ST ($9.2\;kJ/kg^{0.75}\;d$) and $1.3^{\circ}C$ increase in Tb ($17.3\;kJ/kg^{0.75}\;d$).

• Solar Energy
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• v.14 no.2
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• pp.91-101
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• 1994

Heat release characteristics of a CaO packed bed reactor which is used for a chemical heat storage device has been studied. We employed Cu-plate fins to release the heat of reaction of the CaO packed bed inside the reactor fast and effectively. Two-dimensional analysis of unsteady state heat flow inside the bed was performed as a function of time and under various conditions of the Cu-plates. It is noted that the time required to release the heat of reaction with Cu fins is reduced more than twice fast compared to that without Cu fins. That was largely dependent upon the number of Cu-plate, as well.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.37-40
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• 1996

Cable-In-Conduit Conductor(CICC) is widely accepted as an advanced superconductor configuration for large scale applications such as tokamak fusion reactors, MAGLEV (MAGnetic LEVitation), and SMES (Superconducting Magnetic Energy Storage). The stability of CICC cooled with supercritical helium can be very high if it is operated below a certain limiting current. This limiting current can be determined by Stekly type heat balance equation. The stability characteristic of CICC for AC operation is more complicated than that of DC because there are additional instability sources which are associated with local flux change. Ramp-rate limitation is a phenomenon discovered during US-DPC (United States-Demonstration Poloidal Coil) program, which showed apparent quench current degradation associated with high dB/dt. This paper describes recent experimental investigation results on the ramp-rate limitation and discusses current imbalance, induced current, current redistribution due to local quench of the strand in the cable.