This research studied the effect of factors that are able to form disinfection by-products (DBPs) of chlorination, including natural organic matter (NOM) with sewage, bromide ions, pH and contact time. Trihalomethane (THMs) yield of 0.95 μmol/㎎ was higher than other DBPs yield for the chlorinated humic acid samples. THMs yield of sewage sample was 0.14 μmol/㎎ and haloacetonitriles (HANs) yield in the sewage samples were 0.13 μmol/㎎ but only 0.02 μmol/㎎ for the humic acid samples. As the concentration of bromide ions increased, brominated DBPs increased while chlorinated DBPs decreased, because bromide ions produce brominated DBPs. THMs were highest (55.55 ㎍/L) at a pH of 7.9 and haloacetic acids (HAAs) were highest (34.98 ㎍/L) at a pH of 5. Also THMs increased with increasing pH while HAAs decreased with increasing pH. After chlorination, the rate of THMs and HAA formation are faster at initial contact time and then reaches a nearly constant value after 24 hours. This study considers ways to reduce DBP formation by chlorination.

Land prices reflect not only the uses of land, but the potential uses as well(Plantinga, 2002) so land values can be applied to very effective indices for deciding regional status and growing potential. The purpose of this study is to deduce determinant factors of regional land prices. Principal determinants of regional land prices are analyzed with a hedonic technique and spatial econometric models based on 2001 statistic data of Korea except large cities. The results provide the followings. 1. The spatial effect of rural regions are very little with adjacent regions. 2. The common index of land price is population density and other determinant factors are different depending on land uses.

본 연구에서는 여러 가지 요인에 의해 발생하는 홍수위의 변화를 분석하기 위해서 홍수추적모형을 이용하였다. 과거 측량된 하상단면자료를 이용하여 모의수행한 결과 합리적인 경계조건 뿐만 아니라 당시의 하상단면에 대한 정확한 측량이 이루어진 경우에 가장 작은 오차를 발생하였다. 지류의 유입규모에 따른 본류부의 수위 상승 효과를 분석한 결과 본류 및 지류의 유량규모가 커질수록 잠수교 및 한강대교에서의 수위변화량이 상당히 작아지는 것을 확인할 수 있었다. 한강하류

With the help of mechanical mixing method such as Banbury mixer and open 2 roll mill, ethylene propylene diene terpolymer (EPDM) was blended with the chloroprene rubber (CR) then mechanical properties and ozone resistance test of blends were subsequently investigated. It was noted that the hardness increased with an increasing of CR contents. Generally the hardness was increased with heat aging time most likely due to the post cure. In ozone resistance test of blend, after 8 hours a portion of fine crack is obtained for pure CR. It is confirmed that ozone resistance is greatly improved by addition of 25wt% EPDM to CR.

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.