• Agricultural and Biosystems Engineering
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• v.3 no.1
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• pp.10-17
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• 2002

Quality attributes of apple are greatly affected by the cooling rate and environmental conditions during storage. Studies were conducted to evaluate the effect of cooling rate on different quality attributes of apple. The effect of $O_2$ pulldown rate of the CA chamber on the quality of apple was also determined. Two methods were used viz. conventional CA procedure and rapid CA procedure. Apples stored by medium and slow cooling methods lost its flesh firmness significantly from an initial level of 4.55 kg to 2.83 kg and 2.27 kg, respectively on 35 days after storage whereas, in rapid cooling, the firmness level changed from 4.55 kg to 3.20 kg on 35 days after storage. At the end of 35 days of storage, titratable acidity decreased insignificantly from an initial value of 0.24l% to 0.239% in the case of rapid CA whereas in the case of conventional CA it dropped significantly to 0.215% from its initial level. The initial flesh firmness of 4.55 kg also changed significantly to 4.05 kg on 35 days after storage in conventional CA whereas in rapid CA it changed to 4.36 kg, which was found to be non-significant at 5% level of significance. Total soluble solids increased from an initial level of $12.43^{\circ}$Bx to $12.60^{\circ}C.$ Bx on 35 days after storage in rapid CA whereas it increased to $13.07^{\circ}$ Bx in conventional CA. Ascorbic acid content of apple juice decreased insignificantly from 6.67 mg/100 mL to 5.87 mg/100 mL on 35 days after storage in rapid CA whereas in conventional CA, it decreased significantly to 5.27 mg/100 mL from its initial level.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.391-397
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• 1999

Rails are produced by several rolling processes. These processes play an important role on the performance of rails. We analysed the rolling processes by finite element code, DEFORM. The distributions of temperatures and effective strains are obtained. After the rolling processes, the rails are sent to the cooling bed. During the cooling, the rails are bended and twisted. These bending and twisting should be minimized to produce a high quality rail. The analyses of cooling processes and residual stresses produced through the rolling processes will be Presented in the next paper.

• Journal of Life Science
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• v.27 no.5
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• pp.591-599
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• 2017

It is well established that endurance performance is negatively affected by environmental heat stress. Numerous scientific investigations have attempted to improve performance in the heat with pre-cooling and per-cooling for endurance athletes. Some cooling strategies are more logistically challenging than others, and thus are often impractical for use in training or competition. The purpose of this study was to review the literature on the use of cooling interventions in the improvement of performance and recovery from exercise-induced heat stress. We undertook an examination that focused on the effects of pre-cooling and per-cooling on the improvement in endurance performance and the effects of post-exercise cooling on recovery. The benefits for pre-cooling and per-cooling strategies undertaken in the laboratory setting could be employed by athletes who compete in hot environmental conditions to improve performance. Most laboratory studies have shown improvements in endurance performance following pre-cooling and per-cooling, and in recovery following post-cooling. Cooling strategies such as cooling vest, neck cooling collar, menthol and ice slurry are practically relevant to sports field. Cooling interventions that can be applied frequently to reduce thermal strain prior to, during and directly after training appear to be the best effective strategy to improve performance and recovery. Future research is warranted to investigate the effectiveness of practical pre-cooling and per-cooling strategies in competition or field settings.

• Journal of Veterinary Clinics
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• v.8 no.1
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• pp.103-108
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• 1991

It was carried out to investigate the effect of the kind of medium, the concentration of serum added and the temperature of storage on the survival of mouse and bovine embryos preserved In vitro. The survival of frozen-thawed mouse embryos after cooling at 4$^{\circ}C$ was also investigated. It was possible to preserve the embryos of mouse until 4 days and of cattle in a day without significant decrease of the survival rates. The survival rates of frozen-thawed mouse embryos after cooling at 4$^{\circ}C$ over 3 days were below 20%.

• Steel and Composite Structures
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• v.50 no.3
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• pp.281-298
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• 2024

Stainless steel bolts (SSB) are increasingly utilized in bolted steel connections due to their good mechanical performance and excellent corrosion resistance. Fire accidents, which commonly occur in engineering scenarios, pose a significant threat to the safety of steel frames. The post-fire behavior of SSB has a significant influence on the structural integrity of steel frames, and neglecting the effect of temperature can lead to serious accidents in engineering. Therefore, it is important to evaluate the performance of SSB at elevated temperatures and their residual strength after a fire incident. To investigate the mechanical behavior of SSB after fire, 114 bolts with grades A4-70 and A4-80, manufactured from 316L austenitic stainless steel, were subjected to elevated temperatures ranging from 20℃ to 1200℃. Two different cooling methods commonly employed in engineering, namely cooling at ambient temperatures (air cooling) and cooling in water (water cooling), were used to cool the bolts. Tensile tests were performed to examine the influence of elevated temperatures and cooling methods on the mechanical behavior of SSB. The results indicate that the temperature does not significantly affect the Young's modulus and the ultimate strength of SSB. Up to 500℃, the yield strength increases with temperature, but this trend reverses when the temperature exceeds 500℃. In contrast, the ultimate strain shows the opposite trend. The strain hardening exponent is not significantly influenced by the temperature until it reaches 500℃. The cooling methods employed have an insignificant impact on the performance of SSB. When compared to high-strength bolts, 316L austenitic SSB demonstrate superior fire resistance. Design models for the post-fire mechanical behavior of 316L austenitic SSB, encompassing parameters such as the elasticity modulus, yield strength, ultimate strength, ultimate strain, and strain hardening exponent, are proposed, and a more precise stress-strain model is recommended to predict the mechanical behavior of 316L austenitic SSB after a fire incident.

• Journal of the Korean Ceramic Society
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• v.30 no.6
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• pp.469-477
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• 1993

Residual stresses is one of the major factors to degrade the magnetic properties of VCR magnetic heads. Vicker's indentation technique was adapted to estimate the residual stresses Residual stresses and distribution in the glass and ferrite were obtained after bonding ferrite with glass, varing the cooling rate. The compressive and tensile stresses were developed in the interface and gradually decreased with increasing distance from the interface. The stresses were decreased with a cooling rate. The mean values of residual stress in ferrite were 10MN/㎡, 8MN/㎡, 5MN/㎡ with cooling rate 10℃/min, 5℃/min, 1℃/min respectively. When the bonded sample was annealed above the glass transition temperature followed by cooling at 5℃/min cooling rate, the residual stress was reduced to 6MN/㎡.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.156-159
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• 2003

A free piston and free displacer(FPFD) Stirling cryocooler for cooling infrared and cryo-sensors is currently under development at KIMM(Korea Institute of Machinery ＆ Materials). Our coolers are specifically designed to work in the thermal imaging device and to meet requirements such as cooling capacity, COP and high reliability. In this work, Stirling cryocooler is designed, manufactured and fabricated, and performance characteristics are investigated. This cooler delivers approximately 0.5W cooling at 77K for 30W ∼ 40W of input power from AC power supply. And, after the climate performance and reliability for the cryocooler is discussed, operating test without cooling load at the cold end is performed.

• Food Science and Preservation
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• v.3 no.1
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• pp.55-60
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• 1996

To obtain the basic data on precooling effects for establishment the suitable postharvest handling technique or method of keeping high quality of vegetalble corn, the sweet, supersweet and waxy corn, (Danok #2, Cocktail #86 and Chalok #1), being mainly consumed as vegetables in Korea, were precooled with ice or vacuum cooling method immediately after harvest. The vacuum cooling was the most effective for the field heat removal of vegetable corn. It took only 30 min. at 4 to 5 torr of cold chamber pressure of vacuum precooler to lower the corn temperature from 30 to 2$^{\circ}C$. The ice cooling was also thought to be a useful precooling method with relatively short cooling time of 6 hrs. The vegetable corn treated with vacuum or ice cooling showed low and stable respiration rates of 25.5 to 43.5 CO2 mg/kg/hr. when stored at 0∼2$^{\circ}C$ while the samples stored at room temperature (20∼25$^{\circ}C$) without precooling were as high as 64.1 to 245 CO, mg/kg/hr.

• Journal of Embryo Transfer
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• v.23 no.3
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• pp.161-166
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• 2008

The techniques for the collection, cooling and freezing of semen and artificial insemination of horses are not fully understood in Korea. We investigated the percentages of total motile (TM) and progressively motile (PM) sperms after the collection, cooling and freezing of stallion semen. The average volume of semen was 167 ml in Thoroughbred and 68 ml in Arab. The average numbers of spermatozoa in Thoroughbred and Arab were $104\times10^6/ml$ and $86\times10^6/ml$ respectively. The average percentages of TM and PM were 82.3% and 88.6% in Thoroughbred, and 61.4% and 82.6% in Arab, respectively. The average percentage of TM at 4 hr after cooling at $5^{\circ}C$ was significantly lower than that at 0 hr ($30.0\pm4.1%\;vs.\;78.0\pm2.5%,\;p<0.05$), but the percentage of PM was similar between 66.5 and 73.2% at 0, 1, and 4hr. The average percentage of frozen-thawed Thoroughbred semen frozen in MFR5 extender was 56.2%, which was significantly higher than that of the semen frozen in LE extender (average 32.9%, p<0.05). The percentage of TM in Arab was similar for semen frozen in MFR5 extender and LE extender (18.2% and 21.2%, respectively), but the percentage of PM was significantly higher in sperm frozen in MFR5 extender than in sperm frozen in LE extender (69.0% vs. 36.4%, p<0.05). Four mares were artificially inseminated by Thoroughbred frozen-thawed semen and one of them fertilized at 11 day after artificial insemination. In this study, the collection, cooling and freezing of equine semen were possible under domestic conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.8
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• pp.425-432
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• 2009

In this study, the improvement of cooling capacity by applying gas injection technique in a two-stage heat pump using R410A was experimentally investigated. A twin rotary type compressor with gas injection was applied to the heat pump system. The optimum refrigerant charge for the injection and the non-injection cycles was selected to achieve the maximum COP at the cooling standard condition. The injection cycle showed less optimum refrigerant charge than that of the non-injection cycle. The cooling performances of the injection and the non-injection cycles were measured and compared by varying compressor frequency from 40 to 90 Hz. The cooling capacity of the gas injection cycle was 1.6% -11.3% higher than that of the non-injection cycle. The COP of the gas injection cycle was 13.7% to 28.9% higher than that of the non-injection cycle at the same cooling capacity. The heat pump system showed stable operation after 30% of the injection valve opening.