This study examined blends of styrene butadiene rubber(SBR) and chloroprene rubber(CR) prepared from an open 2-roll mill following the conventional polymer blend method for a wide range of the blend composition. Rubber vulcanizates were manufactured by hot press and then mechanical properties, heat and ozone resistance of the specimens were examined. Due to the post cure during the aging test, hardness of vulcanizates was increased. It was found that the undesirable characteristics of heat and ozone resistance of pure SBR was significantly improved through the blending of SBR with CR.

The purpose of this experiment is to prepare ethylene propylene diene terpolymer(EPDM)/acrylonitrile butadiene rubber(NBR) blend which represents good environmental resistant properties including favorable oil and ozone resistance. With incorporation of EPDM, NBR and other ingredients, the rubber and chemical additives were mixed by mechanical method such as Banbury mixer and open 2-roll mill. Then rubber vulcanizates were manufactured by hot press and mechanical properties, oil and ozone resistance of the test specimens were measured. The oil resistance and ozone resistance of EPDM and NBR, respectively, is remarkably improved by blending EPDM with NBR. The optimum results of oil and ozone resistant characteristics were obtained at EPDM/NBR(=25/75 wt%) composition ratio.

밀병(watercore)은 과실의 저장 및 유통 산업에 있어서 큰 영향을 주므로 이를 비파괴측정할 수 있는 기술이 필요하다. 본 연구에서는 투광량을 이용한 사과의 밀병 판별 가능성과 밀병 판별에 영향을 미치는 인자들을 조사하였다. 사과의 화상데이터는 CCD 카메라를 사용하여 영상을 취득하였다. 밀병이 많이 든 사과는 밀병이 적게 든 사과보다 투광량이 더 많았으며 투광량에 의한 사과의 밀병 판별 정확도는 약 70%이었다. 사과의 과피두께, 색소층

The concentration of air pollution in a large city such as Pusan has been increased every years due to the increase on fuel consumption at factories and by vehicles as well as the gravitation of the population. In this study, we have analyzed NO2 concentration data and various data of meteorological factors during 1994-1997 to investigate the characteristics of NO2 concentration and how the high NO2 concentration is generated under the meteorological condition. According to the study, NO2 peak concentration at most sites occurred about 1h later after the rush hour. In the characteristics of emissions in sites, sinpyeong- dong was highly contributed to point source while the other sites were highly contributed to line source. The high NO2 concentration had high generation probability when temperature contained typical seasonal characteristics and wind speed was low. Using the relationship between meteorological factors and the daily average NO2 concentration, correlation analysis was practiced. The seasonal variation of the daily average NO2 concentration was correlated with air temperature, solar radiation and wind speed, but the correlation coefficient between meteorological factors and the daily average NO2 concentration was not so much high. Thus we have known that the daily average NO2 concentration is partially explained by meteorological factors.

The effects of temperature, initial Pb^2+, concentration and initial sludge concentration on the initial Pb^2+ removal rate and maximal Pb^2+ removal amounts in activated sludge, respectively, were investigated. The removal of Pb^2+ in activated sludge was proved to be temperature-dependent process. The initial Pb^2+ removal rate increased from 187.5 to 261.4 ㎎ Pb^2+/g sludge dry weight·min, in response to the promoted temperature from 10℃ to 60℃, while the maximal Pb^2+ removal amount (78.5 ㎎ Pb^2+/g sludge dry weight) occurred at 30℃. As the initial Pb^2+, concentration increased from 36 to 228 ㎎ Pb^2+/L at the constant temperature of 30℃ and initial sludge concentration of 1.5 g sludge dry weight/L, the time to reach an equilibrium state was almost independent of the initial Pb^2+ concentration and the equilibrium Pb^2+ removal amount was increased from 41.9 to 73.6 ㎎ Pb^2+/g sludge dry weight. On the contrary, the equilbrium Pb^2+ removal amount was decreased from 87.7 to 65.3 ㎎ Pb^2+/g sludge dry weight as the increase of initial sludge concentration from 0.22 to 1.76 g sludge dry weight/L.

본 연구에서는 (1) 운동과 이론에 기초한 강우, 유출 특성을 파악하고, (2) 강우 및 유수에 의해서 발생하는 침식, 퇴적량을 산정하는 모형을 연구하며, (3) 유사량 산정식, 유역의 불할 수 등이 하상변동 예측에 미치는 영향을 분석하고, (4) 평창강 유역에서 하도자료, 강우, 유츨량, 유사량 등을 실측하여 모형의 적용성을 검증하였다. 운동파 방정식을 평창강 유역에 적용하여 유출해석을 실시한 결과, 첨두 유량의 발생시간은 다소 빠르게 계산되었으나 전

To perform a long-term ambient sampling study at a residential site, an air sampler was constructed to collect 24-hour integrated air samples suitable for the volatile organic compounds (VOCs) analysis. It includes an esthetically acceptance due to proximity to homes, as well as providing the required sampling specifications. The VOCs sampler accomodates four 5/8 stainless steel(SS) traps packed with adsorbent(Tenax) and is capable of four flow rates in the range of 5 to 50 cc/min. Sintered metal filters(10 micrometer) were directly connected to the inlet of the trap adapters. Additional specifications include: 1) constructed of organically inert materials. 2) weatherproof, 3) battery operated, 4) collecting of VOCs at a breathing zone level, , and 5) quiet operation with micro diaphragm pumps wrapped by the sponge. The pump/battery system was separated from the sampling shelter. Sound levels measured for this system were below permissible sound levels (NJDEP) at a residential site. The sampler has been successfully operated at both ground level in a residential area and on the roof of a one story elementary school.