This study explores reducing the oxygen content of a commercial Ti-48Al-2Cr-2Nb powder to less than 400 ppm by deoxidation in the solid state (DOSS) using Ca vapor, and investigates the effect of Ca vapor on the surface chemical state. As the deoxidation temperature increases, the oxygen concentration of the Ti-48Al-2Cr-2Nb powder decreases, achieving a low value of 745 ppm at 1100oC. When the deoxidation time is increased to 2 h, the oxygen concentration decreases to 320pp m at 1100oC, and the oxygen reduction rate is approximately 78% compared to that of the raw material. The deoxidized Ti-48Al-2Cr-2nb powder maintains a spherical shape, but the surface shape changes slightly owing to the reaction of Ca and Al. The oxidation state of Ti and Al on the surface of the Ti-48Al-2Cr-2Nb powder corresponds to a mixture of TiO2 and Al2O3. As a result, the peaks of metallic Ti and Ti suboxide intensify as TiO2 and Al2O3 in the surface oxide layer are reduced by Ca vapor deposition

In the present work, a new hydrogen added argon heat treatment process that prevents the formation of hydrides and eliminates the dehydrogenation step, is developed. Dissolved hydrogen has a good effect on sintering properties such as oxidation resistance and density of greens. This process can also reduce costs and processing time. In the experiment, commercially available Ti-6Al-4V powders are used. The powders are annealed using tube furnace in an argon atmosphere at 700oC and 900oC for 120 min. Hydrogen was injected temporarily during argon annealing to dissolve hydrogen, and a dehydrogenation process was performed simultaneously under an argon-only atmosphere. Without hydride formation, hydrogen was dissolved in the Ti-6Al-4V powder by X-ray diffraction and gas analysis. Hydrogen is first solubilized on the beta phase and expanded the beta phases’ cell volume. TGA analysis was carried out to evaluate the oxidation resistance, and it is confirmed that hydrogen-dissolved Ti-6Al-4V powders improves oxidation resistance more than raw materials.

Cu-Mn compacts are fabricated by the pulsed current activated sintering method (PCAS) for sputtering target application. For fabricating the compacts, optimized sintering conditions such as the temperature, pulse ratio, pressure, and heating rate are controlled during the sintering process. The final sintering temperature and heating rate required to fabricate the target materials having high density are 700oC and 80oC/min, respectively. The heating directly progresses up to 700oC with a 3 min holding time. The sputtering target materials having high relative density of 100% are fabricated by employing a uniaxial pressure of 60 MPa and a sintering temperature of 700oC without any significant change in the grain size. Also, the shrinkage displacement of the Cu-Mn target materials considerably increases with an increase in the pressure at sintering temperatures up to 700oC.

Waterborne infectious disease is induced by several pathogenic microbes such as bacteria, viruses and protozoans, and the cases caused by viral infection is currently increasing. Water treatment process could reduce the number of virus in the water, but there were many difficulties to completely remove the virus particles from water. Therefore, the membrane separation technology which was reported to effectively remove pollutants from raw water has attracted increasing attention and demand. Since its efficiency has been introduced, demands for evaluation method toward the membrane filtration process are increasing. However, progression of the method development is slow due to the difficulties in cultivation of several waterborne viruses from animal models or cell culture system. To overcome the difficulties, we used adenovirus, one of the commonly isolated pathogenic waterborne viruses which can grow in cell culture system in vitro. The adenovirus used in this study was identified as human adenovirus C strain. The adenovirus was spiked in the raw water and passed through the microfiltration membrane produced by Econity, a Korean membrane company, and then the viral removal rate was evaluated by real-time PCR. In the results, the amount of virus in the filtered water was decreased approximately by 5 log scale. Because coagulant treatment has been known to reduce filtering function of the membrane by inducing fouling, we also investigated whether there was any interference of coagulant. In the results, we confirmed that coagulant treatment did not show significant interference on microfiltration membrane. In this study, we found that waterborne virus can be effectively removed by membrane filtration system. In particular, here we also suggest that real-time PCR method can rapidly, sensitively and quantitatively evaluate the removal rate of virus. These results may provide a standard method to qualifying membrane filtration processes.

Recently, the production of taste and odor (T&O) compounds is a common problem in water industry. Geosmin is one of the T&O components in drinking water. However, geosmin is hardly eliminated through the conventional water treatment systems. Among various advanced processes capable of removing geosmin, adsorption process using granular activated carbon (GAC) is the most commonly used process. As time passes, however GAC process changes into biological activated carbon (BAC) process. There is little information on the BAC process in the literature. In this study, we isolated and identified microorganisms existing within various BAC processes. The microbial concentrations of BAC processes examined were 3.5×105 colony forming units (CFU/g), 2.2×106 CFU/g and 7.0×105 CFU/g in the Seongnam plant, Goyang plant and Goryeong pilot plant, respectively. The dominant bacterial species were found to be Bradyrhizobium japonicum, Novosphingobium rosa and Afipia broomeae in each plants. Removal efficiencies of 3 μg/L geosmin by the dominant species were 36.1%, 36.5% and 34.3% in mineral salts medium(MSM) where geosmin was a sole carbon source.

2009년 4월부터 8월까지 쭈쭈가무시병의 다발생지역으로 알려진 중부지방의 충남 아산시, 경기 평택시와 화성군 3개 지역에서 털진드기의 개체군 밀도를 조사하였다. 채집된 들쥐는 총 48마리였는데 이 중 등줄쥐(A. agrararius)가 45마리로 93.8%를 차지하여 절대 우점종이었고, 갈밭쥐(Microtis fortis)가 1마리(2.0%)였으며, 땃쥐(Crocidura laisura)가 2마리(4.2%)였다. 조사 기간 중 전 지역에서 채집한 털진드기는 총 290개체였다. 채집된 털진드기는 1속 4종이었는데 이중 대잎털진드기(Leptotrombidum pallidum)가 234개체로 80.7%를 차지하여 우점종이었고, 동양털진드기(L. oriental)가 30개체(10.3%), 수염털진드기(L. palpale)가 10개체(3.4%), 반도털진드기(L. zetum)가 16개체(5.5%)였다. 대잎털진드기는 3개 지역(충남, 평택, 화성)에서 절대 우점종으로 나타났다. 충남 아산지역에서는 대잎털진드기, 수염털진드기, 동양털진드기, 반도털진드기 4종이 서식하는 것으로 나타났으며, 경기 평택지역에서는 대잎털진드기, 동양털진드기, 반도털진드기 3종이 서식하며, 경기 화성지역은 대잎털진드기, 수염털진드기 2종만이 서식하는 것으로 나타났다.

This study has been carried out to investigate the non-isothermal behaviors and kinetic parameter of calcium carbonate by different thermal analysis methods. At the heating rate of /min, the onset calcination temperature, the peak and final temperatures of calcium carbonate were , , and respectively. As the heating rate of the calcium carbonate increased from /min to /min, the peak temperature increased from to . The activation energies of the calcium carbonate calculated by the methods of Kissinger and Freeman-Carroll were 40.15 kcal/mol and 43.47 kcal/mol, respectively.

본 연구는 제 5차, 제 6차 및 제 7차 교육과정에 의해 편찬된 311종류의 초, 중등학교 과학 교과서에 인용된 관속 식물의 종류를 파악하고 특징을 분석하였다. 그 결과 인용된 식물은 129과 332속 383종 2아종, 47변종 6품종, 3잡종으로 총 441분류군으로 나타났다. 이 중 초본은 280종류(63.5%), 목본은 161종류(36.5%)였으며, 자생종과 외래종은 각각 241종류(54.6%)와 200종류(45.4%)였다. 과별로는 국화과가 35종류로 가장 많았으며 다음은 벼과가 26분류군으로 나타났다. 인용된 441분류군에는 한국특산식물은 9분류군, 희귀식물 25분류군, 멸종위기식물 12종류, 식물구계학적 특정식물종 83종류와 16종류의 귀화식물이 포함되어 있다. 식물의 용도는 식용이 185종류(41.9%)로 가장 많았으며, 약용 148종류(33.5%), 관상용 139종류(31.5%), 목초용 87종류(19.7%), 목재용 34분류군(7.7%) 등의 순으로 나타났다.