The purpose of this study was to establish an optimal storage temperature and characteristic analysis after frozen-thawed dairy goat sperm. Sperm was collected at Chojeong dairy goat farm using an electric stimulator and dilluted with semen washing media. The egg yolk-triladyl frozen solution was used for the freezing of Saanen dairy goat sperm and the freezing concentration was set to 1×108sperm/ml. The frozen sperm were thawed in water bath at 37.5℃ for 45 seconds and motility was measured after preservation for 0, 30, 60, 90 and 120 min at 4℃, 17℃ and 37℃, respectively. Sperm characteristic analysis was conducted by flow cytometry. In results, sperm motility at 30, 60, 90 and 120 min after thawing was significantly higher in 17℃ than 4℃ and 37℃ (p<0.05). On the other hand, the frozen-thawed sperm motility were gradually decreased with storage periods increased (30, 60, 90 and 120 min) at 4℃, 17℃ and 37℃. Viability(42%), acrosome damage(24%), mitochondrial damage(28%) and ROS level(4%) were analyzed by flow cytometry in frozen-thawed spermatozoa in 7 male dairy goats. In summary, the motility of frozen-thawed spermatozoa in Saanen dairy goat was more efficient for storage 17℃. The average of viability 42%(30%~54%), acrosome damage 24%(16%~33%), mitochondrial damage 28%(20%~54%) and ROS level 4%(3%~6%) were arranged as standard value by 7 male dairy goats. However, more researches are needed to establish the optimal conditions or proper supplementation for sperm preservation. This study was carried out with the support of research project on feasibility study of the research & development projects for activating the hillside livestock farming and the development of goat grazing program of Rural Development Administration by Korea government (2018PJ013546).

PURPOSES: Using recycled asphalt materials (called Reclaimed Asphalt Pavement: RAP) from existing asphalt pavement layers in newly constructed asphalt pavement is an essential option not only for lowering the construction budget but also for mitigating environmental pollution for society. For this reason, many pavement agencies in South Korea, the USA, and Canada have observed the effect of RAP on conventional asphalt pavement to evaluate and set proper material specifications and addable amounts. In this paper, effect of recyclable material on low-temperature performance of asphalt materials was investigated with two different mechanical tests. Among the recyclable material sources, RAP and Taconite Aggregate (TA), which is mainly produced in northern Minnesota (USA), were considered. METHODS : To evaluate the low-temperature mechanical performance of a RAP mixture, two different experimental tests (In-Direct Tensile (IDT) low temperature creep test and Semi-Circular Bending (SCB) test) were considered. The mechanical parameters creep-stiffness, relaxation modulus, fracture energy, and fracture toughness were computed then compared. RESULTS: More brittle characteristics were observed with RAP-added asphalt mixtures compared to the conventional asphalt mixtures, as expected. However, the differences of computed mechanical performances were not significantly distinct for RAP mixtures compared to conventional mixtures when the RAP proportion was around 20%, and with the addition of TA up to 20%. CONCLUSIONS : It can be concluded that up to 20% of RAP addition (along with TA up to 20%) in a virgin asphalt mixture does not provide significant performance reduction. This addable proportion can be viewed as a successful minimum level when considering the addition of RAP to hot-mix asphalt (HMA). Moreover, applying TA with RAP could offer a successful alternative for asphalt recycling and the materials industry.

Vortex tubes are simple tubes that can separate hot and cold air from compressed air without any internal device configuration and are used in many industries. If the vortex tube with these advantages is applied to an air conditioning system, it will be free from the use of refrigerant. In this study, basic study on discharge flow rate and temperature separation characteristics was carried out by varying the number of generator nozzle hole in various shapes of the vortex tube according to the inlet pressure of the vortex tube. Experimental results show that as the number of nozzles increases, the discharge flow rate tends to decrease and the temperature separation characteristics were excellent in the number of nozzles 6~7.