• Advances in concrete construction
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• v.6 no.3
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• pp.285-296
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• 2018

In the present paper, the results of an experimental study of the bond between repair materials and mortar substrate subjected to hot climate is presented. Half-prisms of size $40{\times}40{\times}80mm$, serving as a substrate mortar samples (SUBM) were manufactured in the laboratory and then stored at an ambient temperature for 6 months. Five self compacting mortar mixes (SCMs) incorporating 0%, 10%, 20%, 30%, and 40% of natural pozzolana as white cement replacement were used as repair materials. Repaired composite samples (SCMs/SUBM) were cured at hot climate for different lengths of time (28 and 56-days). During the first week of curing, the composite samples were watered twice a day. The test carried out to assess the bond between SCMs and SUBM was based on three-point bending (3 PB) test. The obtained results have proved that it was feasible to produce compatible repair materals in this curing environment by using up to 30% natural pozzolana as white cement replacement.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.5 no.2
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• pp.91-97
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• 1976

This study was concerned with performance of 2 types of black painted solar air heaters, one is finned type better, the other is mesh type. The performance test of heaters was made under the different operating conditions during winter season of December in Seoul area. It was analized and discussed by comparing the overall efficiency of 2 solar heaters at the same mass flow rate and ambient temperature. Experimental results show that finned type solar heater is better than mesh type from the point of view of design and heat removal efficiency. Finned-type solar air heater supplies hot air up to 30 degree centigrade above ambient temperature with an overall efficiency of 47 percent whilemesh type was 44 percent.

• International Journal of Concrete Structures and Materials
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• v.10 no.1
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• pp.47-60
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• 2016

The objective of this study was to evaluate the capability of different strength-maturity models to account for the effect of the hydration heat on the in-place strength development of high-strength concrete specifically developed for nuclear facility structures under various ambient curing temperatures. To simulate the primary containment-vessel of a nuclear reactor, three 1200-mm-thick wall specimens were prepared and stored under isothermal conditions of approximately $5^{\circ}C$ (cold temperature), $20^{\circ}C$ (reference temperature), and $35^{\circ}C$ (hot temperature). The in situ compressive strengths of the mock-up walls were measured using cores drilled from the walls and compared with strengths estimated from various strength-maturity models considering the internal temperature rise owing to the hydration heat. The test results showed the initial apparent activation energies at the hardening phase were approximately 2 times higher than the apparent activation energies until the final setting. The differences between core strengths and field-cured cylinder strengths became more notable at early ages and with the decrease in the ambient curing temperature. The strength-maturity model proposed by Yang provides better reliability in estimating in situ strength of concrete than that of Kim et al. and Pinto and Schindler.

• Asian-Australasian Journal of Animal Sciences
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• v.4 no.4
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• pp.377-382
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• 1991

The effect of molasses addition and hot temperature on the ensiling characteristics of napier grass (Pennisetum purpureum Schum.) were studied. Napier grass was harvested five times at intervals from 22 to 39 days and each harvest was divided into two equal portions. The half portion was ensiled directly and the other half was ensiled after mixing with molasses into polyethylene bag silos of 15 kg capacity. Molasses was added at the rate of 4% of fresh weight of the grass. One half of the each treatment was conserved at a room of $40^{\circ}C$ for a month and then moved to an ambient temperature room. The other half was kept at ambient temperature for the whole experimental duration. The silages were opened 3 to 7 months after ensiling. Addition of molasses enhanced lactic acid fermentation by increasing lactic acid content and reducing pH value, ammonia nitrogen and acetic, propionic and butyric acid contents of the silages in both temperature treatments. Enhanced temperature increased pH value and decreased acetic, propionic and butyric acids.

• Asian Journal of Atmospheric Environment
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• v.9 no.3
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• pp.194-204
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• 2015

This study analyzed a change trend of ambient temperature over the last sixty years in the largest industrial city in Korea, Ulsan. Linear warming rates in Ulsan over the last 25 (1985 to 2009), 40 (1970 to 2009), and 60 (1950 to 2009) years were 0.0507, 0.0416, and $0.0277^{\circ}C/yr$, respectively. The annual average temperature (AAT) and the annual average of the daily lowest temperature (AADLT) in Ulsan increased 1.3 and $2.9^{\circ}C$, respectively, over the last fifty years (1960 to 2009). The increasing slopes of the AAT and AADLT over the fifty years in Ulsan were higher or much higher than those in neighboring cities and on a global scale. In the comparison analysis of daily average temperature over the most recent ten years, the highest ($15.9^{\circ}C$) was observed in the industrial area followed by the downtown, coastal, suburban, and rural areas with 14.6, 14.5, 14.0, and $12.8^{\circ}C$, respectively. The number of cold days less than $5.0^{\circ}C$ decreased, while the number of hot days higher than $20.0^{\circ}C$ increased. The decreasing slopes in the cold days in lower latitude cities were steeper than those in higher latitude cities in Korea.

• Current Optics and Photonics
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• v.8 no.2
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• pp.138-150
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• 2024

This study is essential for advancing our knowledge about the interaction between long-range high-power lasers and energetic materials, with a particular emphasis on understanding the response of a 155-mm shell under various surface irradiations, taking into account external factors such as atmospheric disturbances. The analysis addresses known limitations in understanding the use of non-realistic targets and the negligence of ambient conditions. The model employs the three-dimensional level-set method, computer-aided design (CAD)-based target design, and a message-passing interface (MPI) parallelization scheme that enables rapid calculations of the complex chemical reactions of the irradiated high explosives. Important outcomes from interaction modeling include the accurate prediction of the initiation time of ignition, transient pressure, and temperature responses with the location of the initial hot spot within the shell, and the relative magnitude of noise with and without the presence of physical ambient disturbances. The initiation time of combustion was increased by approximately a factor of two with atmospheric disturbance considered, while slower heating of the target resulted in an average temperature rise of approximately 650 K and average pressure increase of approximately 1 GPa compared to the no ambient disturbance condition. The results provide an understanding of the interaction between the high-power laser and energetic target at a long distance in an atmospheric condition.

• Journal of Environmental Science International
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• v.27 no.4
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• pp.251-259
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• 2018

This study was conducted to determine the effects of combination of air temperature and soil water content on the growth, physiological disorder rate, and yield of hot peppers. The study was carried out in a typical plastic house (open on one side and with ventilation fans on the other side), which was maintained with gradient air temperature (maximum difference in air temperature: $6^{\circ}C$). The deficit irrigation (DI) treatment commenced 65 days after transplanting. The height of plant and fresh and dry weights of the stem increased at high air temperature (ambient + $6^{\circ}C$, extreme high temperature; EHT). Furthermore, the leaf area decreased significantly with the DI treatment. There were no significant differences in the stem diameter, number of branches, and fresh and dry weights of the leaves among all the treatments. The net photosynthesis rate of the full irrigation (FI) treatment was higher than that of the DI treatment. The photosynthesis rate at ambient air temperature was $19.7{\mu}mol\;CO_2m^{-2}{\cdot}s^{-1}$, the highest among all the treatments; however, the photosynthesis rate of the EHT treatment decreased by 60% ($12.3{\mu}mol\;CO_2m^{-2}{\cdot}s^{-1}$). Additionally, the formation of guard cells in the leaf was abnormal with the EHT treatment, and there was a decrease in translocation efficiency. The effects of air temperature treatment were more pronounced on the physiological disorder rate and yield. The physiological disorder rate of the EHT treatment was the highest under the DI treatment condition. The yield of the AFI (ambient air temperature with full irrigation) treatment was 3,771 kg/10a, the highest among all the treatments; however, the yield of the EHT treatment with DI and FI was 1,282 and 1,327 kg/10a, respectively. These results indicate that growth and physiological disorder rate improved with the EHT treatment; however, there was a decrease in yield. Furthermore, the formation of guard cells was abnormal and malfunctional.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.378-378
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• 2010

The ZnSe epilayers were grown on the GaAs substrate by hot wall epitaxy. After the ZnSe epilayers treated in the vacuum-, Zn-, and Se-atmosphere, respectively, the defects of the epilayer were investigated by means of the low, temperature photoluminescence measurement. The dominant peaks at 2.7988 eV and 2.7937 eV obtained from the PL spectrum of the as-grown ZnSe epilayer were found to be consistent with the upper and the lower polariton peak of the exciton, $I_2$ ($D^{\circ}$, X), bounded to the neutral donor associated with the Se-vacancy. This donor-impurity binding energy was calculated to be 25.3 meV. The exciton peak, $I_l^d$, at 2.7812 eV was confirmed to be bound to the neutral acceptor corresponded with the Zn-vacancy.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.881-891
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• 2008

The purpose of the present study is to investigate the influence of seasonal temperature variation on the thermal stresses in roller compacted concrete dam(RCD) structures. Using the finite element code, DIANA performs 2-D transient temperature and resultant stress analysis for RCD. Time variability of the mesh geometry is considered in order to simulate successive phases of the structure's construction. The main analysis variables are construction sequence, concrete temperature and ambient temperature. The results show principal tensile stress of hot-weathering concrete is higher than that of cold-weathering concrete. In some case the index of thermal cracking excesses 1.0, RCD also needs thermal management on placing temperature according to weather condition.

• Journal of Biosystems Engineering
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• v.31 no.6 s.119
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• pp.529-534
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• 2006

The greenhouse heating system with far-infrared heater was built to analyze various thermal characteristics, such as greenhouse air temperature, soil temperature, energy flow, energy consumption in far-infrared heater, and other factors, which could be used in comparison with other greenhouse heating system in this study. The results showed that the inside air temperature of the far-infrared greenhouse heating system was $5^{\circ}C$ higher than that of hot air heating system. Heat loss of daytime was found to be larger than that of night time as much as 44.8% for the heating system with far-infrared heater. In the heating system with far-Infrared heater, when the lowest ambient temperature was -8 $\sim$ -7$^{\circ}C$, the air temperature of greenhouse was 12 $\sim$ 15$^{\circ}C$, thus the far-infrared heating system was shown to be feasible for heating system. Energy consumption of far-infrared heating system was shown to be less than that of hot air heating system.