Magnesium hydroxide sulfate hydrate (MHSH) whiskers were synthesized via a hydrothermal reaction by using MgO as the reactant as well as the acid solution. The effects of the H2SO4 amount and reaction time at the same temperature were studied. In general, MHSH whiskers were prepared using MgSO4 in aqueous ammonia. In this work, to reduce the formation of impurities and increase the purity of MHSH, we employed a synthesis technique that did not require the addition of a basic solution. Furthermore, the pH value, which was controlled by the H2SO4 amount, acted as an important factor for the formation of high-purity MHSH. MgO was used as the raw material because it easily reacts in water and forms Mg+ and MgOH+ ions that bind with SO4 2- ions to produce MHSH. Their morphologies and structures were determined using X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Cryopreservation of germ cells from genetically proven animals could be a source of restoration tools from the risk of extinction or disappearance of wanted characteristics. Using frozen semen, the genetic gains of Korean native cattle have been increased greatly for 70 years. The preservation of genetic resources as a form of frozen semen straw has limited availability due to the numbers. To circumvent this weakness of frozen semen, we tested two re-freezing methods with different initial thawing temperatures using frozen Korean proven semen and rare breed semen from albino, black and chikso breeders. It has been known that human sperm could resist to cryo-damages by repeated freeze-thaw cycles, but not for Korean proven bulls number (KPN) or for rare breeds. Total 7 frozen semem from brindled(2), black(1), Korean Albino(2) and KPN(1) bulls were used for our research. After thawing straws under 5°C/2min or 37°C/40sec with low temperature water bath and thermo jug, spermatozoa were re-diluted with triladyl diluents after first thawing and re-frozen. Sperm motilities were compared between animals and treated groups after re-thawing. Mean values of motility and viability of refrozen/thawed sperm for expansion of the number of straws were significantly higher in 5°C than in 37°C (P< < 0.05). However, the activity of viable sperm thawed at 5°C was significantly decreased after first and second thawing. It is estimated that re-freezing of frozen semen from rare Korean native cattle is possible with resistant properties of survived spermatozoa.

The aim of this study is to analyze the distribution of particulate matters including PM_2.5 which is known for severe adverse health effect than PM₁₀ in public facilities. The total 40 public buildings are investigated in this study and they are classified into 11 sub-groups as follows : child-care centers, medical centers, libraries, museums, bus terminals, ports, airports, railway terminals, subway stations, large-scale stores, and indoor parking lots. The mean concentration of PM₁₀ was 38.6㎍/㎥ and that of PM₁₀ in all studied facilities were lower than the Ministry of Environment's control standards. The average concentration of PM_2.5 was 27.2㎍/㎥ and that of PM_2.5 in 18 facilities were exceed the guideline of WHO (24h average value : 25㎍/㎥). The subway stations had the highest indoor level of particulate matters and the waiting area in bus terminals, railway terminals, indoor parking lots had followed in order. When comparing mean value of I/O ratio of PM₁₀, the only I/O ratio of subway stations were greater than one. In the case of PM_2.5, however, the average concentrations of PM_2.5 in indoors of subway stations, bus terminals, and indoor parking lots were higher than those of PM_2.5 in outdoors. The mean concentration of PM₁₀ and PM_2.5 were gradually increased between 6 A.M and 10 A.M and after 6 P.M in most of target buildings with increasing the number of users in thest facilities.

본 연구에서는 한국 고등학생들과 영어원어민들의 영어 마찰음에 대한 발음을 음향적으로 비교․분석하였다. 분석 결과, 한국 고등학생들은 음운체계에 존재하지 않는 영어 마찰음을 발음할 때 오류빈도가 그렇지 않은 마찰음 보다 더 높았다. 한국어의 음운체계에 존재하지 않는 영어의 마찰음 가운데 오류율이 가장 높았던 마찰음은 /ð/이었으며 83.70%였다, 또한 /ɵ/는 55%, /v/는 31.67%, /f/는 26.67%, /ʒ/는 21.67%, /z/는 10%, /ʃ/는 9.17%이었으며, 한국어의 음운체계에 존재하는 /s/의 경우에는 전혀 오류를 보이지 않았다. 이러한 결과는, 한국 고등학생들은 조음기관의 앞쪽에서 발음이 되는 마찰음에 어려움을 겪고 있음을 보여준다. 또한 한국인 영어 학습자들은 마찰음에 대한 발음에서 /f/를 /p/로, /v/를 /b/로, /z/를 /s/로 대치하는 경향이 일반적이었고, 마찰음을 발음하면서도 파열을 수반하는 경우도 관찰할 수 있었다.