A bulk-type Ta material is fabricated using the kinetic spray process and its microstructure and physical properties are investigated. Ta powder with an angular size in the range 9-37 μm (purity 99.95%) is sprayed on a Cu plate to form a coating layer. As a result, ~7 mm-sized bulk-type high-density material capable of being used as a sputter material is fabricated. In order to assess the physical properties of the thick coating layer at different locations, the coating material is observed at three different locations (surface, center, and interface). Furthermore, a vacuum heat treatment is applied to the coating material to reduce the variation of physical properties at different locations of the coating material and improve the density. OM, Vickers hardness test, SEM, XRD, and EBSD are implemented for analyzing the microstructure and physical properties. The fabricated Ta coating material produces porosity of 0.11~0.12%, hardness of 311~327 Hv, and minor variations at different locations. In addition, a decrease in the porosity and hardness is observed at different locations upon heat treatment.

The effect of heat treatment environment on the microstructure and properties of tantalum coating layer manufactured by kinetic spraying was examined. Heat treatments are conducted for one hour at 800oC, 900oC, and 1000oC in two different environments of vacuum and Ar gas. Evaluation of microstructure and physical properties are conducted. High density α- tantalum single phase coating layer with a porosity of 0.04% and hardness of 550 Hv can be obtained. As heat treatment temperature increases, porosity identically decreases regardless of heat treatment environment (vacuum and Ar gas). Hardness of heat treated coating layer especially in Ar gas environment deceases from 550 Hv to 490 Hv with increasing heat treatment temperature. That in vacuum environment deceases from 550 Hv to 530 Hv. The boundary between particles became vague as heat treatment temperature increases. Oxygen distribution of tantalum coating layer is minute after heat treatment in vacuum environment than Ar gas environment.

본 연구는 홍도의 식생구조를 식물사회학적 방법으로 군락을 분류하고, 식생과 토양과의 상관관계를 밝히고자 구배분석을 실시하였다. 홍도의 식생은 구실잣밤나무군락, 붉가시나무군락, 후박나무군락, 소나무군락, 소사나무군락으로 구분되었다. 중요치 분석결과 구실잣밤나무가 75.56%로 가장 높았으며, 소나무 34.84%, 후박나무 29.11%, 동백나무 26.88%, 붉가시나무 17.79%, 황칠나무 15.23%, 광나무 13.41%, 소사나무 12.67% 등의 순으로 나타났다. 토양은 매우 높은 유기물과 질소함량을 보이며 표토층에서 강한 산성토양의 특성을 나타내어 우리나라의 일반 산림토양과는 다른 특성을 가지고 있었다. 유기물함량 14.48~25.45%, 전질소함량 0.49~0.90%, 유효인산함량 26.00~58.68㎎/㎏, 치환성양이온 K+는 0.64~1.64cmol+/㎏, Ca2+는 6.22~21.51cmol+/㎏, Mg2+는 2.92~6.95cmol+/㎏, 토양 pH는 4.42~5.44인 것으로 조사되었다. DCCA를 이용한 홍도의 식생과 환경요인과의 상관관계를 분석한 결과, 구실잣밤나무군락이 수분이 가장 많은 곳에 분포하였고, 후박나무군락, 붉가시나무군락 순으로 분포하였다. 후박나무군락이 pH, 치환성양이온 Ca2+, Mg2+, K+, 양이온치환용량 등이 가장 높은 지역에 분포하였다. 소사나무군락이 소나무군락에 비해 해발고, 전질소, 양이온치환용량, 치환성양이온 Mg2+ 등이 높은 지역에 분포하였다.

Cryopreservation of epididymal spermatozoa offers a potential tool for rescuing genetic material from males of genetically elite populations. Castration, catastrophic injury, sudden death or any other event that makes semen collection or mating impossible may prematurely terminate a stallion reproduction. Stallion epididymal spermatozoa vary widely in the loss of progressive motility, acrosomal integrity, and viability during freezing and thawing. The objective of this work was to investigate the effect of (1) freezing package types on cryopreservation efficiency, (2) thawing temperatures (37, 56 or 70℃) on Computer Assisted Sperm Analysis (CASA) parameters and (3) post-thawing incubation time (0, 1, 2 or 4h) on castrated stallion epididymis. Post-thawed sperm motility ranged between 59.69% and 64.28% (56℃ and 37℃) in various thawing temperatures. When stallion epididymis sperm was frozen, straw was better than freezing tube on VCL (Velocity of Curvilinear Line) and VAP (Velocity of Average Path) parameter. Higher percentage of motility was observed at 37℃ thawing temperature even though no significant difference was observed among various temperatures. The motility, VCL, ALH (Amplitude of Lateral Head displacement), VAP, BCF (Beat-Cross Frequency) and STR (Straightness index) parameter of post-thawed sperm were significantly decreased by increasing the incubation time for all thawing temperatures. The present study showed that type of freezing package (Straw vs. Freezing tube) was not significantly different on cryopreservation efficiency. Furthermore, stallion epididymal spermatozoa frozen-thawed at 37℃ for 1 min resulted the highest proportion of motility and velocity movement. In addition, motility and viability of frozen-thawed stallion epididymal spermatozoa were also decreased by incubation.

Horse population has been gradually increasing with the growth of the racing industry in Republic of Korea (ROK). Approximately 22,941 horses including native ponies were raised on 1,142 farms in 2006. Great care has been taken to prevent viral, bacterial and parasitic infections in horses. However, there has been few reports on equine infectious anemia (EIA) in ROK until recently since 1987. Therefore, we conducted a serological survey of EIA in ROK from 2007 through 2009. Using the agar gel immunodiffusion test, a total of 2,601 horses were tested in Foreign Animal Disease Division of Animal, Plant, and Fisheries Quarantine and Inspection Agency. This survey found no serological evidence of EIA presence in ROK. Although our surveillance found no evidence of EIA in ROK during the surveillance period, it is possible that EIA could be introduced into ROK in the near future. Increased cooperation between the government and other agencies, such as horse-racing authorities, is important for both the early detection of the disease and the development of effective veterinary and public health strategies.

DNA damage such as genotoxicity was identified with comet assay, which blood cell of a marine parrot fish (Oplegnathus fasciatus) was exposed to an acidified seawater, lowered pH gradient making of CO2 gas. The gradient of pH were 8.22, 8.03, 7.81, 7.55 with control as HBSS solution with pH 7.4. DNA tail moment of fish blood cell was 0.548 ± 0.071 exposed seawater of pH 8.22 condition, on the other hand, DNA tail moment 1.601 ± 0.197 exposed acidified seawater of pH 7.55 lowest condition. The approximate difference with level of DNA damage was 2.9 times between highest and lowest of pH. DNA damage with decreasing pH was significantly increased with DNA tail moment on blood cell of marine fish (ANOVA, p < 0.001). Ocean acidification, especially inducing the leakage of sequestered CO2 in geological structure is a consequence from the burning of fossil fuels, and long term effects on marine habitats and organisms are not fully investigated. The physiological effects on adult fish species are even less known. This result shown that the potential of dissolved CO2 in seawater was revealed to induce the toxic effect on genotoxicity such as DNA breakage.