• Proceedings of the KWS Conference
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• 1994.05a
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• pp.57-59
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• 1994

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.185-188
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• 1997

The influence of slow cooling and annealing time in $O_2$ during melting and growth step in MPMG process on J$_{c}$ was investigated. Through the measurement of J$_{c}$ SEM and XRD, it can be observed that the critical characteristics were related with the slow cooling time and annealing time in 02 for melting and growth step of MPMG process. The distribution of critical current density with slow cooling time was the porabolic form and the value of J. was the highest at the 40 hour slow cooling time. And also, the value of J$_{c}$, along the annealing time in $O_2$ in the case of the slow cooling time 40 hour was inclined to increase with annealing time. Consequently, it can be suggested that proper slow cooling titre and annealing time along slow cooling in MPMG process be important to improve the critical characteristics.stics.

• Journal of Microbiology and Biotechnology
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• v.6 no.3
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• pp.209-212
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• 1996

A two-step cooling technique has been developed for cryopreservation of suspension cultured Scutellaria baicalensis cells. Efficient regrowth of cryopreserved cells was obtained in cryoprotected cells with a mixture of 1.5 M glycerol and 0.4 M sucrose in Schenk and Hildebrandt medium without pretreatment in high osmotic medium. Optimum freezing conditions were found to be a cooling rate of $0.5^{\circ}C$ min from $4^{\circ}C$ to $-40^{\circ}C$, and then retaining samples at $-40^{\circ}C$ for 30 min prior to plunging into liquid nitrogen. A regrowth rate of approximately 95$%$ was obtained after three month storage in liquid nitrogen. Callus cultures established from the cryopreserved cells were found to produce the same patterns of flavonoid accumulation and retain their baicalin producing activity.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.882-887
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• 2014

In this paper, the water cooling method among the forced coolant cooling methods is considered to be applied to the 110kW-class IPMSM for railway vehicles. First, basic thermal property analysis of the IPMSM is conducted using the three-dimensional thermal equivalent network method. Then, based on the results of the basic thermal property analysis, some design requirements for the water cooling jacket are deduced and a basic design of the water cooling jacket is carried out. Finally, thermal equivalent circuit of the water cooling jacket is attached to the IPMSM's 3D thermal equivalent network and then, the basic thermal and effectiveness analysis are conducted for the case of applying the water cooling jacket to the IPMSM. In the future, the thermal variation trends inside the IPMSM by the application of the water cooling jacket is expected to be quickly and easily predicted even at the design step of the railway traction motor.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.1
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• pp.43-50
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• 2024

Large planar military antenna boasts a range of electrical components, including TRA(Transmit-Receive Assembly), signal processors, etc. which engage in computations and calculations. These processes generate a significant amount of heat, leading to unforeseen consequences for the equipment. To mitigate these adverse effects, it's imperative to implement a cooling system that can effectively reduce heat-related issues. Given the antenna's intricate nature and the multitude of components it houses, a two-step estimation process is necessary. The first step involves a comprehensive model calculation to determine the total flow characteristics, while the second step entails a thermal analysis of individual TRA set. In this study, we depicted an antenna set using simplified 3D models of its components, considering their material and thermal properties. The sequential analysis process facilitated the calculation of branched flow rates, providing insights into the individual TRA. This approach also allowed us to design a cooling system for the TRA set, assessing its thermal stability in high-temperature environments. To ensure the optimal performance of TRA, breaking down the analysis into stages based on the cooling system's structure can assist operators in predicting numerical results more effectively.

• Journal of Aerospace System Engineering
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• v.6 no.2
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• pp.35-41
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• 2012

A reciprocating engine installed on a normal category airplane shall be effectively cooled by air flown through the engine compartment. A airplane powerplant designer has to design cooling air inlets, baffles, seals, and outlets to maintain cylinder head temperatures and oil temperature under the limits, and show compliance with appropriate airworthiness standard. In this study, cooling designs of the installed engine and compliance requirements applicable to the cooling designs were reviewed, and engine cooling flight test results were evaluated for design changes. Engine cooling certification test will be conducted in a next step.

• Journal of Korea Foundry Society
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• v.38 no.2
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• pp.41-47
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• 2018

In a numerical study, equations relating the mechanical properties and cooling rate in a casting process have been applied to an AC4CH cast aluminum alloy. Good agreement was found between the measured and predicted material properties. Step-shaped steel blocks were made to comprise a casting mold with a Y-shaped cavity. Thermometers were inserted into each step of the mold to investigate temperature changes. The microstructure and mechanical properties, such as hardness and tensile stress were measured for each cut of piece. The correlation between the cooling rate and SDAS was found by curved fitting. Moreover, both the solidification time and the temperature were simulated using a commercial package, ZCast. The simulation results for yield strength, tensile strength, elongation, and hardness were compared with experimental results. Using the estimated K and n values, the hardness values of a ship propeller were simulated, and the results were similar to those obtained for actual castings.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.11
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• pp.943-956
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• 2003

A numerical program has been developed for the simulation of automotive engine cooling system. The program determines the mass flow rate of engine coolant circulating the engine cooling system and radiator cooling air when the engine speed is adopted by appropriate empirical correlation. The program used the method of thermal balance at individual element through the model for radiator component in radiator analysis. This study has developed the program that predicts the coolant mass flow rate, inlet and outlet temperatures of each component in the engine cooling system (engine, transmission, radiator and oil cooler) in its state of thermal equilibrium. This study also combined the individual programs and united into the total performance analysis program of the engine cooling system operating at a constant vehicle speed. An air conditioner system is also included in this engine cooling system so that the condenser of the air conditioner faces the radiator. The effect of air conditioner to the cooling performance, e.g., radiator inlet temperature, of the radiator and engine system was examined. This study could make standards of design of radiator capacity using heat rejection with respect to the mass flow rate of cooling air. This study is intended to predict the performance of each component at design step or to simulate the system when specification of the component is modified, and to analyze the performance of the total vehicle engine cooling system.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.237-240
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• 2003

Gas turbines are extensively used in flight propulsion, electrical power generation, and other industrial applications. During its life span, a turbine blade is taken out periodically for repair and maintenance. This includes re-coating the blade surface and re-drilling the cooling holes/channels. A successful laser re-drilling requires the measurement of a hole within the accuracy of ${\pm}0.15mm$ in position and ${\pm}3^{\circ}$ in orientation. Detection of gas turbine blade/vane cooling hole position and orientation thus becomes a very important step for the vane/blade repair process. The industry is in urgent need of an automated system to fulfill the above task. This paper proposes approaches and algorithms to detect the cooling hole position and orientation by using a vision system mounted on a robot arm. The channel orientation is determined based on the alignment of the vision system with the channel axis. The opening position of the channel is the intersection between the channel axis and the surface around the channel opening. Experimental results have indicated that the concept of cooling hole identification is feasible. It has been shown that the reproducible detection of cooling channel position is with +/- 0.15mm accuracy and cooling channel orientation is with +/$-\;3^{\circ}$ with the current test conditions. Average processing time to search and identify channel position and orientation is less than 1 minute.

• ALGAE
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• v.18 no.4
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• pp.321-331
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• 2003

Cryopreservation of sporothalli of the red alga Porphyra (P. seriata, P. yezoensis, P. tenera, P. pseudolinearis and P. dentata) was performed by the two-step cooling method in liquid nitrogen. The algal samples were suspended in various cryoprotective solutions, and slowly cooled to -40$^{\circ}C$ in 4 hours using a programmed freezer. After the first slow cooling the suspensions with cryoprotectants were immediately immersed in liquid nitrogen. The suspension from the programmed freezer was thawed quickly by agitation of the vial in a water bath at 40°C. When ice in the suspension of cryogenic vial was mostly melted, the vial was transferred to an ice bath for complete melting of the residual ice. The cryoprotectants in the vial were washed off by gradual dilution with seawater. The viability of the cell was assessed with neutral red staining. The viability of Porphyra samples ranged 54.6-70.9% when the mixed suspension of 10% dimethylsulfoxide and 0.5 M sorbitol in 50% seawater used as a cryoprotectant.