In the metallothermic reduction (MR) process used to obtain tantalum powder in one batch, it is difficult to control the morphology and location of the tantalum deposits. On the other hand, an electronically mediated reaction (EMR) process is capable of overcoming this difficulty. The effect of using as the raw material and sodium as the reducting agent on the characteristics of tantalum powder are investigated. As the temperature of the reduction varied from 1023K to 1223K, the powder particles obtained with MR were relatively large , while those prepared via EMR were of uniform . In the MR process, the Ta powder recovery rate increased from 37% to 83% at 1123K in constrat with EMR process.

For indoor air quality at a newly built apartment before move-in, we monitored formaldehyde and VOCs and assessed human exposure and probabilistic health risk. We selected 801 newly built apartments all over the country. The results of the research on the condition show the mean concentrations of formaldehyde 294 ㎍/㎥, 210(median) 1497㎍/㎥(maximum), benzene 6㎍/㎥, (4 and 92㎍/㎥), toluene 1003㎍/㎥(773 and 5013 ㎍/㎥), ethylbenzene 120㎍/㎥, (62 and 1192㎍/㎥), xylene 287㎍/㎥(138 and 2723㎍/㎥) and styrene 64㎍/㎥, (42 and 531㎍/㎥). Formaldehyde from carcinogen and toluene and xylene from non-carcinogen were assessed the risk for human health. The excess cancer risk of formaldehyde for human beings between carcinogens is per 1.36 of average 1000 persons. This implies that it is over a level per 1.00 of 1000 persons demanding active risk reduction. Hence, we strongly need the active reduction plan and accurate source assumption. Among a variety of factors affecting indoor air quality for householders, closing construction or density of indoor air processing additional interior construction and indoor area, indoor air quality with a variety of districts show significant. The excess cancer risk for human beings of formaldehyde between carcinogens is per 1.36 of average 1000 persons. Non-carcinogen toxicity rate for human-beings with toluene and xylene among non-carcinogens is over HQ 1 from Seoul to local area.

Recently, indoor air quality (IAQ) in workplace, residence, and schools has been one of the major concerns of people, scientists and the related public. This study was performed to investigate the characteristics of indoor air quality(IAQ) in kindergartens, elementary school, middle schools, and high schools from June 2004 to May 2005 in Korea. We measured indoor air pollutants such as PM10, CO2, formaldehyde, total bacteria colony(TBC), CO, radon, total volatile organic compounds(TVOCs), asbestos, and O3 from school classrooms. The subjects were classified by building year based on the time span of 1, 1 - 3, 3 - 5, and 5 - 10 years. The levels of pollutants and physical factor in schools were compared with standards and guidelines of indoor air quality on the Ministry of Environment, the Ministry of Health and Welfare, and the Ministry of Education, and Human Resources Development of Korea. The major results obtained from this study can be summarized as follows. Asbestos and O3 were not detected in all surveyed classrooms. However, we were able to detect CO, TBC, TVOCs, and formaldehyde in kindergartens, TBC in elementary schools, TBC, TVOCs and formaldehyde in middle schools, and formaldehyde in high schools. This study was conducted to provide a basis for the management IAQ in school. Therefore, we suggest that a national plan for the management of IAQ in school should be established through a long-term, continuous investigation for the proper assessment of IAQ in school and for the health risk assessment for student.

Indoor air quality tends to be the dominant contributor to personal exposure, because most people spend over 80% of their time indoors. In this study, indoor and outdoor NO2 concentrations were measured simultaneously with personal exposures of 30 university students in weekday and weekend in Daegu, Korea. House characteristics and subject's activity pattern were used to determine the effects on personal exposure. Since university students spent most of their times indoor, their NO2 exposure was associated with indoor NO2 level during both weekday and weekend in spite of different time activity. Using a time-weighted average model, NO2 exposures of university students were estimated by NO2 measurements in indoor home, indoor school, and outdoor home. In conclusion, major personal exposure to NO2 resulted from air quality of indoor environment at house.

남해 중앙부해역의 해양환경특성을 파악하기 위해 표층 퇴적물중의 와편모. 조류 시스트와 유기물 분포에 대한 조사를 2002년 4월부터 2003년 1월가지 총 6회 실시하였다. 분석 항목 중 함수율, 강열감량, 화학적 산소요구량, 입자성 유기탄소, 입자성 유기질소, 식물색소량은 각각 38.7~68.9% 3.9~ 12.5%, 9.60~44.05 m9O2 gdry-1, 3.12~13.14mgC gdry-1, 0.49~

Nickel powders were synthesized by the hydrazine reduction of nickel chloride solution containing ammonia in DEA solutions. The size distribution of nickel powders were investigated as a function of ammonia concentration, hydrazine concentration and the mixed composition ratio of diethanolammine (DEA) and triethanolammine (TEA). Nickel powders with the size in submicron range were obtained at for 45 minutes by hydrazine reduction of nickel chloride solution in DEA solutions. The hydrazine concentrations showed significant effects on the particle size and shape distribution of nickel powders under molar ratio of 2.0 condition. As the mixed volume ratio of TEA and DEA increased, nickel powders with relatively larger particle size and low agglomeration were obtained. Nickel powders with particle size in the ranged from 0.4 to were obtained at the 50 of TEA.

We investigated the characteristics of the thermohaline structure and phytoplankton community from the southwestern areas of Jeju to the nothern areas of Taiwan in the Ease China Sea, in June 2004. According to the analysis of a T-S diagram, three characteristic of water masses were identified. We classified them into the mixed water mass by the Chiness continental coastal waters and Yellow Sea cold water (Region A), Chinese continental coastal waters (Region B) and Taiwan warm current (Region C). Region A was characterized by low temperature, low salinity, high density and high Chl-a concentration. Region B was characterized by high temperature, low salinity, low density and high Chl-a and Region C was characterized high temperature, high salinity, low density and low Chl-a concentration. The phytoplankton community identified a total of 56 species belonging to 31 genera. The dominant species was mainly dinoflagellates, Gymnodinium breve, Scrippsiella trochoidea, Ceratium fusus, Prororcentrum triestinum, centric diatoms, Chaetoceros lorenzianus, Leptocylindrus danicus, Proboscia alata, Skeletonema costatum and pennate diatoms, Pseudonitzschia pungens, Cylidrotheca closterium. Standing crops of phytoplakton fluctuated between 0.1×102 cells/L and 5.7×104 cells/L by dominance of dinoflagellates. In the phytoplankton community, the Region A was characterized by the various species composition in 39 species, the dominint species with di-atomes, Pn. pungen, Ch. lorenzianus and standing crops from 6.9 cells/ml to 56.6 cells/ml, Region B by the various species composition in 37 species, the dominant species with dinoflagellates, G.breve, S. trochoidea and standing crops from 4.6 cells/ml to 26.7 cells/ml, and the Region C by low species number with 28 species, the dominant species with one dinoflagellate, S.trochoidea and one diatom, L.danicus and very low standing crops from 0.1 cells/ml to 5.7 cells/ml. Phytoplankton productivity in the East China Sea was controlled by Chinese continental coastal waters which include a high concentrations of nutrients.

전국 4개 대도시(서울, 부산, 대전, 광주)를 중심으로 시중에서 유통되는 김밥 중 황색포도상구균의 오염도 자료와 환경조건별 미생물 변화를 예측하는 Food MicroModel^R을 활용하여 김밥 중 황색포도상구균으로 인해 식중독이 발생하지 않을 유효기간을 산정하였다. 분식점(n=79), 백화점(n=10), 편의점(n=20)으로 구분하여 분석한 여름철 평균 황색포도상구균 모니터링자료(검출률 각각 39.2%, 30%, 15%)를 시중에서 유통되는 김밥 중 황색포도상구균의 최대 섭취유효시간 산정에 활용하였으며, 모델 운영 시 김밥 중 황색포도상구균으로부터 enterotoxin이 생성되는 균수인 2×^7에 도달하는데 ℃~ 요되는 시간을 최대섭취유효시간으로 추정하였다. 하절기의 환경조건을 고려하기 위하여 ℃ 온도 조건하에서, pH, NaCl %, aw 0.99의 조건을 적용하였다. 추정된 최대섭취유효시간은 일반적인 성인이 김밥 1인분(171 g)을 섭취하는 것을 기준으로 하였을 때 구입 이후 28~30℃에서 방치할 경우 분식점은 3.9~4.6시간, 백화점 6.7~7.9시간, 편의점은 7.4~8.7시간이었다. 또한 구매한 김밥이 황색포도상구균에 기인한 식중독으로부터 안전할 최대섭취 유효시간은 99% 안전 확률에서 여름철 분식점 자료를 근거하여 30℃에서 1.9시간이었으며 15℃인 경우는 17.7시간이었다.

Polycyclic aromatic hydrocarbons(PAHs)의 인체에 대한 위해성 정도를 판단하기 위해 PAHs의 대표독성물질인 benzo(a)pyrene의 독성을 기준으로 하는 TEFs를 적용하여, PAHs의 주요노출식품에 의한 위해성 평가를 수행하였다. 숯불구이쇠고기, 숯불구이돼지공기, 숯불구이닭고기, 햄, 베이컨, 및 식용유지 등을 대상으로 PAHs 오염도를 모니터링한 결과 숯불구이닭고기에서 총 PAHs농도가 9.3 ppb로 가장 높게 검출되었으며 각각의 congener들 모두 다른 식품에서 보다 높게 나타났다. 반면에 숯불구이쇠고기, 베이컨, 숯불구이돼지고기, 햄 및 식용유지의 총 PAHs는 각각 0.2 ppb, 0.3 ppb, 0.7 ppb, 0.8 ppb 및 1.2 ppb로 비교적 낮은 값을 나타냈다. TEFs값을 적용하여 환산된 오염도 값의 경우에서도 숯불구이닭고기가 가장 높은 값을 보였고, congener들의 농도를 비교했을 때 숯불구이닭고기, 숯불구이돼지고기, 베이컨, 숯불구이쇠고기 및 햄에서 모두 BaP의 농도가 각각 1.88 ㎍-TEQ_BaP/kg, 0.19 ㎍-TEQ_BaP/kg, 0.08 ㎍-TEQ_BaP/kg, 0.04 ㎍-TEQ_BaP/kg 및 0.02 ㎍-TEQ_BaP/kg로 congener들 중 가장 높게 나타났고 식용유지에서는 dibenzo(a, h)anthracene의 농도가 0.21㎍-TEQ_BaP/kg으로 가장 높은 값을 나타냈다. 우리나라 사람들의 PAHs 주요노출식품 섭취로 인한 만성1일인체노출량은 4.32×10^-4 ㎍/kg/day으로 산출되었으며 선정된 식품 중에서 숯불구이닭고기의 노출기여도가 가장 높았다. PAHs의 초과발암위해도는 만성1일인체노출량과 BaP의 발암력인 7.3 (mg/kg/day)^-1을 고려하였을 때 3.44×10^-6, 백만명동 3~4명 수준이어다. 우리나라 대표식단을 통한 PAHs 노출량을 반영할 수 있는 위해성 평가각 추후 계속되어야 할 것으로 사료된다.