• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.20 no.2
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• pp.1-10
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• 2024

The introduction of the sector coupling concept has expanded the scope of ESS utilization, resulting in the importance of thermal management of ESS. To ensure the safe use of the lithium-ion batteries that are used in ESS, it is important to use the batteries at the optimal temperature. To examine the utilization of liquid cooling in ESS, numerical study was conducted on the thermal characteristics of 21700 battery modules (16S2P array) during liquid cooling using Novec-649 as insulating fluid. The NTGK model, an MSMD model in ANSYS fluent, was used to investigate thermal characteristics on the battery modules with liquid immersion cooling. The results show that the final temperature of the battery module discharged at 5 C-rate is 68.9℃ using natural convection and 48.3℃ using liquid cooling. However, the temperature difference among cells in the battery module was up to 0.5℃ when using natural convection cooling and 5.8℃ when using liquid cooling, respectively, indicating that the temperature difference among cells was significantly increased when liquid cooling was used. As the mass flow rate increased from 0.01 kg/s to 0.05 kg/s, the average temperature of the battery module decreased from 48.3℃ to 38.4℃, confirming that increasing the mass flow rate of the insulating fluid improves the performance of liquid immersion cooling. Although partial liquid immersion cooling has a high cooling performance compared to natural convection cooling, the temperature difference between modules was up to 8.9℃, indicating that the thermal stress of the battery cells increased.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.413-418
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• 2002

The dough was frozen either before or after fermentation at the five different freezing and storage conditions. Although fermentation before freezing was effective for rapid freezing, it reduced bread volume of the dough frozen at both air freezer and liquid immersion freezer. Freezing at the air freezer set to $-70^{\circ}C$ took more time for freezing and resulted in lower bread volume than freezing at the immersion freezer set to $-20^{\circ}C$. Therefore, the freezing in the liquid immersion freezer was more effective to reduce the freezing time and increase the bread volume. At the liquid immersion freezer, the higher temperature was more effective than lower temperature. The doughs frozen in a liquid immersion freezer set to $-10^{\circ}C$ and fermented after de-frosting produced higher bread volume than control unfrozen dough. And also there was no significant difference in bread volume between the control unfrozen dough and the dough frozen in a liquid immersion freezer set to $-10^{\circ}C$, fermented before freezing and re-fermented after defrosting. The longer proof time and greater loaf volume obtained for the dough frozen and stored at the air freezer set to $-70^{\circ}C$. Therefore the optimum process for freezing the dough was freezing immediately after mixing, storing at $-10^{\circ}C$ in a liquid immersion freezer and fermented after defrosting.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.5
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• pp.199-205
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• 2018

A geopolymer was produced from coal ash generated from an integrated gasification combined cycle (IGCC) plant and its water resistance was evaluated. For this purpose, the geopolymer specimens were immersed in water for 30 days to measure changes in microstructure and alkalinity of the immersion liquid. Particularly, the experiment was carried out with foaming status of the geopolymers and parameters of room temperature aging condition, and immersion time. The foamed geopolymer containing 0.1 wt% Si-sludge had pores with a diameter of 1 to 3 mm and exhibited excellent foamability. Also, the calcium-silicate-hydrate crystal phase appeared in the foamed geopolymer. In the geopolymer immersion experiment, the pH of the immersion liquid increased with time, because the un-reacted alkali activator remained was dissolved in the immersion liquid. From the pH change of the immersion liquid, it was found that geopolymer reaction in the foamed specimen was completed faster than the non-foamed specimen. Through this study, it was possible to successfully produce foamed and non-foamed geopolymers recycled from IGCC coal ash. Also the necessary data for the safe application of IGCC coal ash-based geopolymers to areas where water resistance is needed were established; for example, the process conditions for room temperature aging time, effect of foaming status, immersion time and so on.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.308-318
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• 1988

The liquid disintegration and characteristics of atomization through the swirl nozzle is affected by injection pressure and injection time when the liquid is injected intermittently. These transient phenomena are investigated by electronic controlled-fuel injection nozzle. The effect of injection conditions on disintegration of liquid injected through nozzle is observed photographically by using delay circuit. Droplet size of the element of the sample is measured by the liquid immersion sampling technique. SMD of droplets is varied with time and is decreased as the injection pressure increases. As the injection pressure increases, the maximum diameter of droplet and diameter of droplet which has the maximum droplet number decrease. Spray angle is not affected on injection pressure and change of spray angle with time is associated with needle movement.

• Archives of Pharmacal Research
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• v.26 no.10
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• pp.880-885
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• 2003

Research in this paper focuses on the kinetic evaluation of swelling of the liquid crystalline phases of glyceryl monooleate (GMO). Swelling of the lamellar and cubic liquid crystalline phases of GMO was studied using two in vitro methods, a total immersion method and a Franz cell method. The swelling of the lamellar phase and GMO having 0 %w/w initial water content was temperature dependent. The swelling ratio was greater at $20^{\circ}^C than 37^{\circ}^C$ . The water uptake increased dramatically with decreasing initial water content of the liquid crystalline phases. The swelling rates obtained using the Franz cell method with a moist nylon membrane to mimic buccal drug delivery situation were slower than the total immersion method. The swelling was studied by employing first-order and second-order swelling kinetics. The swelling of the liquid crystalline phases of GMO could be described by second-order swelling kinetics. The initial stage of the swelling (t < 4 h) followed the square root of time relationship, indicating that this model is also suitable for describing the water uptake by the liquid crystalline matrices. These results obtained from the current study demonstrate that the swelling strongly depends on temperature, the initial water content of the liquid crystalline phases and the methodology employed for measuring the swelling of GMO.

• Progress in Superconductivity and Cryogenics
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• v.19 no.2
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• pp.1-8
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• 2017

Recently, Research and development activity of HTS (High Temperature Superconducting) power application is very progressive worldwide. Especially, HTS cable system and HTSFCL (HTS Fault current limiter) system are proceeding to practical stages. In such system and equipment, cryogenic cooling system, which makes HTS equipment cooled lower than critical temperature, is one of crucial components. In this article, cryogenic cooling system for HTS application, mainly cable, is reviewed. Cryogenic cooling system can be categorized into conduction cooling system and immersion cooling system. In practical HTS power application area, immersion cooling system with sub-cooled liquid nitrogen is preferred. The immersion cooling system is besides grouped into open cycle system and closed cycle system. Turbo-Brayton refrigerator is a key component for closed cycle system. Those two cooling systems are focused in this article. And, each design and component of the cooling system is explained.

• Korean Journal of Materials Research
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• v.17 no.4
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• pp.192-197
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• 2007

The effects of immersion time in the liquid nitrogen on the behavior of aluminum alloys used for the hydrogen storage tank of auto-mobile at cryogenic temperature were investigated. With increasing immersion time in the liquid nitrogen, the elongation of AI 5083 alloy at cryogenic temperature decreased because of non-uniform fracture of precipitates on the grain boundary, and the serration also occurred because of discontinuous slip due to rapid decreasing of the specific heat. The mechanical properties of AI 6061 alloy at cryogenic temperature were characterized by uniformed yield strength, tensile strength and elongation regardless of the immersion time in the liquid nitrogen. These mechanical properties of aluminum alloys at cryogenic temperature were interpreted by the strength of grain boundary and the slip deformation behavior.

• Journal of Soil and Groundwater Environment
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• v.25 no.4
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• pp.58-66
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• 2020

Since the typical horn-type ultrasonic equipment induces a reaction at the probe tip, the sonochemical reaction has a limitation that it occurs only in a specific area. As one of the ways to overcome this limitation, an ultrasonic device with multi-stepped horn equipped with several oscillators has been developed. The objective of this study was to investigate the sonochemical effects induced by acoustic cavitation system in 20 kHz multi-stepped ultrasonic horn using calorimetry, KI dosimetry and the luminol test. The sonochemical effects of multi-stepped ultrasonic horn were compared with that of the typical horn-type 20 kHz ultrasonic device. The effect of immersion depth and power on the sonochemical reaction was investigated in the ultrasonic system with multi-stepped ultrasonic horn. Higher calorimetric energy was obtained at higher immersion depth and power conditions. Sonochemical effects increased significantly when using the high immersion depth and input power. However, as the input power increased, the cavitation reaction zone concentrated around the ultrasonic horn. Additionally, the experiments to examine the effect of liquid temperature was conducted. The smaller sonochemical reaction was obtained for the higher liquid temperature. The effect on temperature seems to be closely related to liquid conditions such as viscosity and vapor pressure of water.

• Journal of Plant Biotechnology
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• v.33 no.2
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• pp.117-122
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• 2006

Comparative studies on medium supply in bioreactors (raft, immersion and ebb and flood) have revealed that multiplication and growth of Alocasia Amazonica were greatest in the raft system, while lowest in ebb and flood system. In the raft system, the basal part of the shoots was continuously in contact with medium, which enabled a constant uptake of nutrients as well as aeration to the explants. The number and the size of leaf stomata were higher in the raft system compared with immersion and ebb&flood system. In the immersion system, plantlets were deformed and epidermal cells in leaves were irregular with a large intercellular space. The results suggested that the medium supply should be controlled properly to maintain normal and healthy plantlets during liquid cultures in bioreactors Which affects morphology and physiology Of the plantlets.

• Journal of Sensor Science and Technology
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• v.18 no.4
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• pp.322-326
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• 2009

To estimate the measurement uncertainty for industrial platinum resistance thermometers(IPRTs) made with 3-wire connection, the immersion temperature profile was investigated using a liquid bath. Two types of IPRTs having lead wires made of silver and nickel were constructed and the immersion profiles were measured at temperatures from -50 $^{\circ}C$ to 250 $^{\circ}C$ using 3-wire and 4-wire method. As immersion depth and temperature increased, the resistances measured by 3-wire method increased linearly but not for 4-wire method. To calibrate a 3-wire IPRT, the immersion effect must be accounted for. We propose a linear equation to assess correctly the measurement uncertainty.