• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.196-201
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• 2003

When the structures are used in cold regions, the mechanical properties and dimension stability of the blade will be changed. The proposal of this study is to test the durability of the structures in cold regions. It is necessary to select the most comfortable materials and fabrication processes for more stable structures in cold regions. To select the most comfortable materials and processes, the static strength has to know through the tensile static tests at the severe condition as cold regions. First, the tensile static specimens made by RIM (Resin injection molding) process & vacuum bagging process with reinforcement materials and resin. Tensile static tests were carried out on three laminate lay-ups (carbon prepreg, carbon fiber dry fabric) at different test temperature($24^{\circ}C$, $-30^{\circ}C$), determining properties such as the mechanical strength, stiffness and strain to failure. At different test temperature, in order to test the tensile strengths of these specimens used the low temperature chamber. Next, the results of this test were compared with each other. Finally, the most comfortable materials and fabrication processes can select based on these results. The results show the changes in the static behavior of three laminate lay-ups at different test temperatures. At low temperatures, the static strengths are higher than the ones at room temperature.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1116-1122
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• 2009

As a result of this study, we reached the following conclusions. With appropriate setting of oil pressure and flow rate, it operated same rotation speed with existing cooler by electrical transmission. In initial operation, a temperature of a cold storage is lower rapidly. As an internal temperature of a cold storage is lower, a decreasing rate of temperature is lower. As a result of comparing the both type, the cooler of oil pressure type showed the following results. The decreasing rate of temperature was more faster and shorter operating time was more shorter than existing cooler of electric type. The actual case of a cold storage, the cooler of oil pressure type can prevent quality deterioration and decrease power consumption. As an internal temperature of a cold storage is lower, power consumption increased rapidly, the oil pressure type showed lower power consumption. COP of two of these types decreased continuously as the internal temperature of a cold storage being reach setting temperature, and that of oil pressure type showed higher amount about 25%. As a setting temperature is lower, the number of refrigerator's operating times are less and operating time is longer, so power consumption is increased in the maintenance of a cold storage's internal temperature, power consumption of hydraulic type showed lower amount about 21~25% in two of these types.

• Progress in Superconductivity and Cryogenics
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• v.26 no.1
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• pp.20-24
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• 2024

Over the past four years, as the COVID-19 pandemic has struck the world, cold chain of COVID-19 vaccination has become a hot topic. In order to overcome the pandemic situation, it is necessary to establish a cold chain that maintains a low-temperature environment below approximately 203K (-70℃), which is the appropriate storage temperature for vaccines, from vaccine suppliers to local hospitals. Usually, cryocoolers are used to maintain low temperatures, but it is difficult for small-scale local distribution to have cryocooler due to budget and power supply issues. Accordingly, in this paper, a cryogenic TSU (Thermal storage unit) system for vaccination cold chain is designed that can maintain low temperatures below -70℃C for a long time without using a cryocooler. The performance of the TSU system according to the energy storage material for using as TSU is experimentally evaluated. In the experiments, four types of cold storage materials were used: 20% DMSO aqueous solution, 30% DMSO aqueous solution, paraffin wax, and tofu. Prior to the experiment, the specific heat of the cold storage materials at low temperature were measured. Through this, the thermal diffusivity of the materials was calculated, and paraffin wax had the lowest value. As a result of the TSU system's low-temperature maintenance test, paraffin wax showed the best low-temperature maintenance performance. And it recorded a low-temperature maintenance time that was about 24% longer than other materials. As a result of analyzing the temperature trend by location within the TSU system, it was observed that heat intrusion from the outside was not well transmitted to the low temperature area due to the low thermal conductivity of paraffin wax. Therefore, in the TSU system for vaccine storage, it was experimentally verified that the lower the thermal diffusivity of the cold storage material, the better low temperature maintenance performance.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.4
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• pp.11-16
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• 2015

Spatial and temporal information on near-surface air temperature is important for understanding global warming and climate change. In this study, the estimation algorithm of near-surface air temperature in Korea was developed by using spatial homogeneous surface information obtained from satellite remote sensing observations. Based on LST(Land Surface Temperature), NDWI(Normalized Difference Water Index) and NDVI(Normalized Difference Vegetation Index) as independent variables, the multiple regression model was proposed for the estimation of near-surface air temperature. The different regression constants and coefficients for warm and cold seasons were calculated for considering regional climate change in Korea. The near-surface air temperature values estimated from the multiple regression algorithm showed reasonable performance for both warm and cold seasons with respect to observed values (approximately $3^{\circ}C$ root mean-square error and nearly zero mean bias). Thus;the proposed algorithm using remotely sensed surface observations and the approach based on the classified warm and cold seasons may be useful for assessment of regional climate temperature in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.5
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• pp.429-444
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• 1991

Cold stress influence plant growth through a wide range of growth characters. Adverse effects of low temperature to plant growth come from results of colligative and complex physiological responses to cold stress. To evaluate more exactly cold tolerance of crop plant, it is needed to observe physiological changes induced by cold stress and to analyze relationships between intraspecific variations in physiological factors related to cold tolerance and the extent of cold tolerance in the field. Therefore, the composition and unsaturation ratio of fatty acids in phospholipid, a constituent of membrane, the transition-temperature in respiratory activity of mitochodria, the chlorophyll fluorescence as a factor related to photosynthesis were investigated in rice plant and data on these factors were compared with the degree of cold tolerance obtained in the field experiment. Also, effects of hardening and Mn++ treatment were evaluated as a method to reduce chilling injuries. The unsaturation ratio of fatty acids, whether rice plants were grown in a natural condition or under the chilling stress, was higher in the cold- tolerant varieties and was significantly correlated with the degree of cold tolerance (1-9) observed in the field experiment. And it was also increased by chilling treatment or hardening treatment, due to a reduction in palmitic acid content and an increase in linolenic acid content. The transition-temperature of respiratory activity of mitochodria isolated from etiolated rice seedlings ($25^{\circ}C$, two week-grown in the dark), was correlated with the degree of cold tolerance in the field, cold -tolerant varieties showing a lower transition-temperature. It was not influenced by growth stages. The intensity of chlorophyll fluorescence was highly correlated with the degree of cold tolerance, cold-tolerant varieties having a higher fluorescence intensity. By foliar application of Mn, the transition-temperature of respiratory activity was lowered as much as 0-2$^{\circ}C$ in all tested varieties. Soil application of Mn induced more significant effect in cold-susceptible varieties with a possibility of reducing chilling injuries. On the whole, there were high correlationships among the degree of cold tolerance, the unsaturation ratio of fatty acids in phospholipid, the transition- temperature of respiratory activity and chlorophyll fluorescence except for a few varieties. The transition- temperature of respiratory activity appeared to be negatively correlated with the unsaturation ratio of fatty acids. and the chlorophyll fluorescence to be positively correlated with the unsaturation ratio. This implies that these physical and physiological factors were very closely related to cold tolerance and can be used as an effective index of the evaluation of cold tolerance of crop plant. But other factors as well as three factors discussed above are needed to be considered colligatively and altogether with a systematic analysis for the more exact evaluation of cold tolerance. in rice cultivars. in rice cultivars.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.2
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• pp.79-86
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• 2011

Cold-air drainage and pooling occur in most mountain valleys at night. Local climates with cold-air pooling could affect phenology and distribution of crop plants. A high resolution infrared imaging radiometer was used to visualize the cold-air drainage and thermal belt formation over a small mountainous watershed (ca. $10{\times}5{\times}1$ km for the maximum length${\times}$width${\times}$depth). Thermal images on $640{\times}480$ pixels were scanned across the Akyang valley (south of Mt. Jiri National Park) by the radiometer installed at a local peak ('Hyongjebong', 1,117 m a.s.l.) at dawn of 17 May 2011, when the synoptic condition was favorable for the surface cooling and cold-air drainage. Major findings are: (1) Cold-air drainage and accumulation was clearly identified by the lowest brightness temperature mainly at the valley bottom. (2) So-called 'thermal belt' with higher brightness temperature was found partway up the valley sidewalls and showed up to $5^{\circ}C$ departure from the valley bottom temperature. (3) Digital thermography showed feasibility for validation of the high definition geospatial temperature models currently in use for the plot-specific agrometeorological service.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.836-845
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• 2016

The variation and structure of the cold water mass around Ganjeol Point during the summer of 2011 were studied using data from CTD observations and temperature monitoring buoys deployed at 20 stations off the southeast coast of Korea. There was a $-12^{\circ}C$ surface temperature difference between the cold water mass and normal water during the monitoring period. Variations in the isothermal lines for surface temperature along the coast showed that the seabed topography at Ganjeol Point played an important part in the distribution of water temperature. Cold water appeared when the wind components running parallel to the coast had positive values. The upwelling -response for temperature fluctuations was very sensitive to changes in wind direction. Vertical turbulent mixing due to the seabed topography at Ganjeol Point can reinforce the upwelling of cold bottom water. From wavelet analysis, coherent periods found to be 2-8 days during frequent upwelling events and phase differences for a decrease in water temperature with a SSW wind were 12-36 hours.

• East Asian Journal of Business Economics (EAJBE)
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• v.11 no.1
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• pp.41-51
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• 2023

Purpose - The prior literature has shown that there is a lack of a complete assessment of the key decisions in cold chain logistics. Such a study is required to offer recommendations for research in this expanding but under-researched topic with potentially significant management ramifications. Research design, Data, and methodology - The current researcher accumulated peer-reviewed sources from databases to augment each chosen study's validity. Selection varied between seminal works and much of the existing literature. The selection process was consistent with using a content checklist that established the inclusion and exclusion criteria. Result - The research findings indicate total five solutions regarding better decision in Cold Chain Logistics (CCL), such as (1) Pricing Decision in Cold Chain Logistics, (2) Decision on Temperature Control Decision in Cold Chain Logistics, (3) Supply Chain Network Design in Cold Chain Logistics, (4) Decision on Minimizing Inventory in Cold Chain Logistics, (5) Decision on Logistics Distribution. Conclusion - Stability of a cold chain should be maintained from manufacture or via logistical components and cold logistics products are susceptible to several variables, such as temperature, and degradation can easily harm food supply, product prices, and human health. Product safety infractions substantially impact human health, among other losses linked with a functioning CCL.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.6
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• pp.1410-1415
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• 2008

Acupuncture and herbal treatment are based on diagnosis of cold and heat pattern in Traditional Korean Medicine. This diagnosis is accomplished through pulse, tongue and question examination, which are not objective. Quantification and objectification of this diagnosis process are required for efficacious treatment and traditional medicine development. In this study, we developed the cold-heat pattern questionnaire for this purpose. Seventy nine patients who visited oriental medical hospital were included in this study. The cold-heat pattern questionnaire was composed of many questions about patient's physical condition, which were derived from The Traditional Oriental Medical Literature with Delphi Technique. Patients filled out the cold-heat pattern questionnaire by themselves. Diagnosis of cold and heat pattern are conducted separately by oriental medical doctors with more than 5 years' clinical experience. Various physical condition factors were derived for the cold-heat pattern questionnaire. (Preference temperature, Body temperature, Pain type, Face color, Urine, Stool and secretion features) Each cold and heat symptoms group acquired internal consistency. (Cronbach's ${\alpha}$ : Cold - 0.605, Heat - 0.722) There were significant associations between doctor's diagnosis and cold symptoms in 'Aversion to cold', 'Desire for heat', 'Pale face', 'Loose stools'. (p-value < 0.05) There were significant associations between doctor's diagnosis and heat symptoms in 'Desire for cold', 'Body feverishness', 'Thirst'. (p-value < 0.05) The internal consistency results suggest that the cold-heat pattern questionnaire assured reliability. Besides, these results showed that cold-heat symptoms are apt to appear together with, and this can be indirect evidence that diagnosis of cold-heat pattern is valuable for comprehension about disease pattern. Moreover, respective symptoms of cold-heat pattern showed different significance with doctor's diagnosis. Consequently these significant symptoms can be more considered for comprehension of cold-heat pattern.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.12 s.255
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• pp.1188-1195
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• 2006

This paper examines the critical air temperature at which frost formation does not occur on a cold plate in order to improve the efficiency of a heat pump. The critical air temperature on test points is obtained from numerical analysis and a correlation of the critical air temperature is derived as a function of frosting factors (air absolute humidity, air velocity, and cold plate temperature) by least square method. Experiments are carried out to verify the correlation proposed in this study, and the prediction obtained with the correlation agrees well with the experimental data. Based on the correlation, we propose the non-frosting regions according to frosting factors.