PURPOSES : Durability of concrete is traditionally based on evaluating the effect of a single deterioration mechanism such as freezing & thawing action, chloride attack, carbonation and chemical attack. In reality, however, concrete structures are subjected to varying environmental exposure conditions which often results in multi-deterioration mechanism occurring. This study presents the experimental results on the durability of concrete incorporating air-cooled slag(AS) and/or water-cooled slag(WS) exposed to multi-deterioration environments of chloride attack and freezing & thawing action. METHODS: In order to evaluate durable performance of concretes exposed to single- and multi-deterioration, relative dynamic modulus of elasticity, mass ratio and compressive strength measurements were performed. RESULTS: It was observed that multi-deterioration severely affected durability of concrete compared with single deterioration irrespective of concrete types. Additionally, the replacement of cement by AS and WS showed a beneficial effect on enhancement of concrete durability. CONCLUSIONS : It is concluded that resistance to single- and/or multi-deterioration of concrete is highly dependent on the types of binder used in the concrete. Showing the a good resistance to multi-deterioration with concrete incorporating AS, it is also concluded that the AS possibly is an option for concrete materials, especially under severe environments.

The world-wide need to reduce the energy used and the greenhouse gases emitted during cement manufacture has led to the pursuit of more eco-efficient materials, such as ground granulated blastfurnace slag(GGBS) and fly ash. Especially, GGBS is a by-product generated during the manufacture of pig ions. GGBS can be divided into water-cooled slag(WS) and air-cooled slag(AS). With comparison of WS, the AS is formed by allowing the molten slag to cool relatively slowly under ambient conditions. This study presents experimental findings on the mechanical and durability performance of cement concrete pavement with replacement of cement by WS and/or AS. In order to produce concrete specimens, total replacement of cement by GGBS(WS+AS) was fixed at 40% by mass. Concrete specimens were regularly monitored for the variation of mechanical properties such as flexural strength, compressive strength and initial surface absorption. In addition, in order to assess durability of concrete pavement with WS and/or AS, the chloride ion penetration resistance and scaling resistance tests were adopted, and the corresponding results were compared to those of plain concrete pavement. The test results indicated that the performance of concrete pavement was significantly dependent on the replacement level of WS by AS. Concrete specimens incorporating 20% replacement level of AS showed a poor mechanical performance, while 5% replacement of AS showed a beneficial effect both mechanical and durability performance. Especially, the 5% AS replacement led to the higher resistance of concrete pavement against frost-salt action. Based on the experimental results, the present study would be helpful to design high-performance cement concrete pavement.

In this study, we conducted laboratory tests to evaluate the moisture resistance of the asphalt mixture containing air-cooled slag. Generally, in Korea, hydrated lime is used up to 1.5% of the aggregate weight to improve the moisture resistance of the asphalt mixture. The slag used in this study is a byproduct produced in the steel industry and can be produced through a specific process. And its chemical composition is similar to that of the hydrated lime stone and satisfies the filler quality standards of the Ministry of Land, Transport and Transport. In order to evaluate the moisture resistance of the asphalt mixture containing air-cooled slag, we conducted the dynamic immersion test, which is a non-compaction mixture test. Also we conducted the indirect tensile strength ratio test and the Hamburg wheel tracking test for compaction asphalt mixture test. As a result of the dynamic immersion test, the effect of stripping prevention was similar to that of hydrated lime because it did not show much difference from the hydrated lime mixture. In the case of indirect tensile strength test, the specimens prepared in the laboratory and on the site satisfied the quality standards of the Ministry of Land, Transport and Logistics and the TSR value increased with increasing the content of air-cooled slag. However, when the content of air-cooled slag is more than 2%, the indirect tensile strength value is getting lower. So it is judged that the appropriate content should be determined to be 2% or less. In the case of the Hamburg wheel tracking test, when the steel wheel load passed 20,000 times on the asphalt mixture containing 2% of air-cooled slag, it showed 5.27mm deformation. And the stripping point was not observed. In this study, it was found that when the air-cooled slag is used as a substitute for hydrated lime, the moisture resistance of the asphalt mixture can be improved. It is considered that the aircooled slag can be used for the asphalt pavement material through the characteristics analysis of mechanical and field application in the future

Stream of afterglow of an atmospheric pressure plasma can conveniently be used for large scale decontamination operations. In the present study, an afterglow dielectric-barrier discharge air plasma (ADDAP) was used to inactivate Escherichia coli O157:H7 as a model microorganism for studying the plasma inactivation effect. The plasma was generated at current levels in the range of 0.4 - 0.8 A. The power consumption of ADDAP generation system ranged 169.5 - 221.9 W with respect to the current intensity range. At this current level, the temperature observed in the treatment chamber remained less than 30℃. Regarding chemical composition of ADDAP in the treatment chamber, NOx species were predominantly generated. The levels of NOx species increased as the current intensity increases and the maximum NO and NO2, concentrations noted were 6 and 4 ppm, respectively, but that of CO was less than 1 ppm level at 0.8 A. Upon treating with the ADDAP generated at 0.4 - 0.8 A for 180 min, E. coli O157:H7 showed 1.24 – 2.71 log reductions. The inactivation patterns exhibited better fit to Weibull-tail model. The comparison of delta values indicated that superior inactivation effects were observed as the current intensity increased.

The aim of this research was to determine the effect of drying conditions (drying air temperature and drying time) on drying rate, effective diffusivity, and activation energy during hot-air drying of jujube slices. Jujube slices were dried in a laboratory scale convective hot-air dryer at an air temperature in a range of 50-70℃ with an air flow of 0.66 m/s. Sliced jujubes did not exhibit a constant-rate drying period and all the drying operations are seen to occur in the falling rate period. At the beginning of drying process, drying rate was very high, and drying rate continued to decrease as moisture content approached to equilibrium moisture content. It is apparent that drying rate decreases continuously with decreasing moisture content or increasing drying time. It is also noted that the drying rate increased with the increase in drying air temperature. The drying rate was more for jujube slices dried at higher temperature than the ones dried at lower temperature for the same average moisture content of the sample. Consequently, the drying time decreased at a higher drying air temperature condition. Moisture transfer from jujube slices was described by applying the Fick's diffusion model and the effective diffusivity changed between 1.354×10-10 and 2.787×10-10 m2/s within the given temperature range. Effective diffusivity increased linearly with increasing temperature. An Arrhenius relation with activation energy values of 33.22 kJ/mol for jujube slices by hot-air drying expressed the effect of temperature on the diffusivity.

Dehydration is the one of the simplest ways to improve the shelf-life of fruits and vegetables by reducing the moisture content. Dehydration operations are important steps in food processing industry, which involves a process of moisture removal due to simultaneous heat and mass transfer. Drying provides a longer shelf-life to the food, cheaper transportation cost, and smaller space demand during storage. Hot-air drying of hamcho pieces were carried out to compare the influence of blanching at 90℃ for 5 min as a pre-treatment on the drying kinetics at temperatures of 50℃, 60℃, and 80℃ at a constant airflow velocity of 0.66 m/s. The pretreatment had significant effects on the moisture content of the hamcho samples. In all the drying temperature selected, the blanched samples had shorter drying time than the control. Based on these comparisons it is seen that blanching treatment prior to drying could improve the drying kinetics of hamcho samples at all drying temperatures. The activation energy was calculated by plotting the natural logarithm of drying rate constant (k) versus the reciprocal of the absolute temperature. It turned out to be 36.90 and 30.76 kJ/mol for the control and blanched sample, respectively.

During insect development from embryo to adult, airway clearance in tracheal system occurs episodically each time the molt is completed by performance of the ecdysis sequence. We found that the neuropeptide Kinin is required for normal respiratory fluid clearance or “tracheal air-filling” in fruit fly Drosophila larvae. Disruption of Kinin signaling leads to defective air-filling during all larval stages. Targeted Kinin receptor silencing in tracheal epithelial cells also shows tracheal air-filling defect. On the other hand, promotion of Kinin signaling in vivo through peptide injection or Kinin neuron activation induces premature tracheal collapse and air-filling. Moreover, direct exposure of epithelial cells in vitro to Kinin leads to calcium mobilization in tracheal epithelial cells. Our findings strongly implicate the neuropeptide Kinin as an important regulator of airway clearance via intracellular calcium mobilization in tracheal epithelial cells of fruit fly Drosophila.

Recently, various building integrated wind power (BIWP) approaches have been used to produce energy by installing wind power generators in high-rise buildings constructed in urban areas. BIWP has advantages in that it does not require support to position the turbine up to the installation height, and the energy produced by the wind turbine can be applied directly to the building. The accurate evaluation of wind speed is important in urban wind power generation. In this study, a wind tunnel test and computational fluid dynamics (CFD) analysis were conducted to evaluate the wind speed for installing wind turbines between buildings. The analysis results showed that the longer the length of the buildings, which had the same height, the larger the wind speed between the two buildings. Furthermore, the narrower the building’s width, the higher the wind velocity; these outcomes are due to the increase in the Venturi effect. In addition, the correlation coefficient between the results of the wind tunnel test and the CFD analysis was higher than 0.8, which is a very high value.

In this study, the loading rates (or emission rate) and concentrations of air pollutants (ammonia, hydrogen sulfide, carbon dioxide, methane, nitrous oxide, and particulate matter (PM2.5, PM10 and TSP)) emitted from a naturally ventilated dairy facility were analyzed and compared to enable a better understanding that are in close proximity to each other, air pollution status. In general, the pollution patterns should be similar in measurement sites that are in close proximity to each other, and this hypothesis was fundamental to our approach in this study. For the comparison in nearby different sites, monitoring points were located at inside (source site) and outside the dairy building (ambient site), and concentrations and wind velocity were simultaneously monitored in real time. The patterns of PM2.5 emission rate and loading rate were similar in the source site and the ambient site which was consist with the hypothesis, while the PM2.5 mass concentration were not similar in both sites. As well as PM2.5, the emission rates (source site) of gaseous carbon dioxide (CO2) and nitrous oxide (N2O) were highly correlated to their loading rates (ambient site), while the concentrations of CO2 and N2O were not similar. Therefore, wind velocity, which is included in the emission or loading rate, should be simultaneously monitored with the concentration at the same measurement points for better understanding of the air pollution status.