• 한국환경과학회지
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• 제8권4호
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• pp.497-502
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• 1999

Removal of Pb(Ⅱ), Cu(Ⅱ), Cr(Ⅲ), and Zn(Ⅱ) ions from aqueous solutions using the adsorption process on domestic loess minerals has been investigated. Variations of contact time, pH, adsorption isotherms and selectivity of coexisting ions and leachate were experimental parameters. YDI, YPT and KRT samples diluted in 1% aquous solution which was adjusted pH 10.8, 8.0 and 6.50, respectively. The result of XRD measurement, Quartz was mainly observed in all samples. In the case of KRT sample, Kaolinite, Feldspar, Chlorite consisting of clay minerals shows almost same pattern with YPT samples. Different properties showed from the YDI sample containing Iillite, remarkably. For all the metals, maximum adsorption was observed at 30min∼60min. Adsorption of metal ions on loess minerals were reached an equilibrium by shaking the solution for about 30min. Removal efficiency of Pb(Ⅱ) ion for KRT, YPT and YDI were 84.7%, 92% and 100%, respectively. The Cu(Ⅱ) and Zn(Ⅱ) adsorptivity on KRT showed the low in various pH solution However, those on YPT and YDI were high than 90% except for the pH 2 solution. The orders of adsorptivities for domestic loess minerals showed as following : YPT>KRT>YDI. The adsorption isotherms of Cu(Ⅱ) and Zn(Ⅱ) ions on clay minerals were fitted to a Freundlich's. Freundlich constants(1/n) of KRT and YPT domestic loess minerals were 0.63, 0.97 and 0.36, 0.25, respectively.

• 한국환경과학회지
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• 제6권5호
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• pp.513-520
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• 1997

This study was performed to investigate the riverbed structure and the pollution type in Nakdong River, Western Nakdong River. and Suyoung Stream. Sediment and water samples were collected at is in Nakdong River. in Western Nakdong River, and 8 states In Suyoung Stream from February 20, 1997 to June 15, 1997. The depth distributions of sampling sites in the three streams were measured and heavy metals(Cd, Pb, Cr, Cu) and pesticides in sediments and COD, BOD, and total nitrogen(T-N) in water samples were analysed. The deepest and the shallowest sites were strate 11(11.58m) and 9(3.35m) in Nakdong River, site 7(6.25m) and 4(2.06m) in Western Nakdong River, and site 8(2.89m) and 1(0. 61m) in Suyoung Stream , respectively. The mean concentration of Cd(45.79ppm) was higher In the sediment of Western Nakdong River than In other two streams and those of Pb(76.25ppm), Cr(48.13ppm), and Cu(77.50ppm) were higher in file sediment of Suyoung Stream than in other two streams. Pesticides(1 kind of organophosphorus and 3 kinds of organochlorine pesticide) were detected only in the sediment of Western Nakdong River. The mean concentrations of COD(20.26ppm), BOD(25.36ppm), and T-N(18.05ppm) were higher in the water sample of Suyoung Stream than In other two streams.

• 한국대기환경학회지
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• 제16권2호
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• pp.89-102
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• 2000

A total of 318 particulate sample sets consisting of both fine PM(FPM : dp$\leq$2.5 ${\mu}{\textrm}{m}$) and coarse PM(CPM : 2.5${\mu}{\textrm}{m}$${\mu}{\textrm}{m}$) was collected by a dichotomous sampler in Suwon area from December 1996 to November 1997. The concentration of seven inorganic elements such as pb. Cr, Cd, Cu, Zn Fe and Na were determined from each sample using an AAS. The purpose of the study was to extensively investigate environmental behaviors of particulate matters and to provide air quality management schemes applying various statistical approaches. The mean concentrations of PM10 Results of correlation analyses indicated the existence of strong correlations among inorganic elements PM10 FPM CPM and various meterological variables. Our study also examined the degree of uncertainties whether the particular elements can be assorted into the accumulation mode or the coarse mode in their size distribution. Furthermore the analysis of the pollution rose showed graphically the direction of potential sources of particulate matters. According to statistical analyses of our data quantitative differences appeared in the pollution patterns between weekdays and weekends.

• 환경위생공학
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• 제22권2호
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• pp.75-84
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• 2007

A lysine determination method for low quantity of rice was modified from the original Dye-Binding Lysine (DBL) method used in the national standard in China [GB 4801-84, 1984]. By making use of the property that lysine does not bind to the crocein orange G dye after treated with propionic anhydride, the amount of lysine in rice samples could be determined directly by calculating the difference between the absorbances of the treated and the untreated samples. Various commercial rice samples were purchased from market and evaluated. Several methods were tested by varying both the sizes of the samples and the concentrations of the dye solutions. Results showed that when using 1.284 mM of crocein orange G dye solution and 15.5 mg of sample, the results were most reproducible. The corresponding lysine content in sample were $3.36\;{\pm}\;0.09\;mg/g$ and $3.35\;{\pm}\;0.19\;mg/g$ by traditional method and modified method, respectively. Statistically, there was no significant difference between the results (p>0.05).

• 자원환경지질
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• 제32권3호
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• pp.307-315
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• 1999

Four organic polymers were mixed with mothmorillonite. Two cationic polymers a hi로 molecular weight polyacrylamide (494C) and a low molecular weight polymer (587C).Two anionic polymers include a high molecular weight polymer (aerotil). Each clay supension series were allowed to stand for 24 hours and were centrifuged, and the clay plugs were washed and dried. The dried samples investigated by XRD, IR and CEC measurement. The suspended clay containing anionic polymers was not flocculated at any concentratuons of polymer. But the suspendions containing two cationic polymers were rapidly flocculated at almost all concentrations. the d(001) spacings of Na-montmorillonite after being with cationic polymer 587C show about 15$\AA$ suggesting the polymers may have entered the interlayer spaces. The polymer 494C-treated sample produced double peaks of about 12 and 15$\AA$ in XRD. It indicates that the high molecular weight polymer. And cationic polymer 494C may be adsorbed mainy on the outside surface of clay, and some polymers may peretrate into olny interlayers in the margin of montmorillonite particles because of its high molecular weught. CEC of polumer 587-treated sample was reduecd mmarkedly suggesting polymer blocks CEC sites. The d(001) spacings of Ca-montmorillonite after being treated with cationic polymers show about 15$\AA$ suggesting that the interlayer spaces have not been expanded. In the experiment using a dilute Ca-bearing solution, the suspended caly containinf anionic polymers was flocculated. The results indicate that the flocculation behavior of montmorillonite-polymer supension depends on not only polymer properties such as concentration, electric charge and molecular weight but also compositions of solvent.

• 지식경영연구
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• 제17권3호
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• pp.117-136
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• 2016

External knowledge search is critical to expand the firm's knowledge base, increasing the innovation performance. However, prior literature has paid less scholarly attention on the boundary condition of the search activity. In particular, the few literatures on the contingency factors are either conceptual or focus on the firm characteristics such as resources and capability. In this regard, this study argues the negative moderating effect of knowledge protection and environmental uncertainty of a firm on the positive relationship between external knowledge search and innovation performance, because these contingency factors hamper the reciprocity and the mutual trust between the firm and its external partner that provides knowledge needed in the innovation process. The empirical analysis is based on the sample drawn from Korean Innovation Survey, provided by STEPI in Korea. The sample consists of 1,637 respondent firms that experienced product innovation during the survey period. We could find statistically supporting results for the negative moderating effect on the positive relationship between external knowledge search and innovation performance. This study extends the academic debate on the boundary conditions of external knowledge search and provides managerial implications for successful product innovation.

• 한국환경보건학회지
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• 제16권2호
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• pp.31-39
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• 1990

An analytical method for particulate carbon and other elements by using elemental analyzer was investigated. Carbon, hydrogen, and nitrogen was determined as CO$_{2}$, H$_{2}$, and N$_{2}$, respectively. Organic was determined after scparation from elemental carbon(Cae) by volatilization and thermal decomposition in a heated helium flow. With organic materials examined in this reprot, more than 90% of carbon was detected as above 600$^{\circ}$C. But it is considered that a few percents of some compounds were charred above 550$^{\circ}$C. A small amount of Cae was oxidized in the inert atmosphere above 850$^{\circ}$C, but the reason was not explained clearly. Based on the thermal chracteristics of Cao it was found that the optimum temperature of heating in the helium flow of an elemental analyzer for Cao analysis is 630$^{\circ}$C. Carbon in a sample after removing Cao was assumed as Cae and the gramatom ratio of hydrogen to carbon in the sample was 0.4 and less. Rescovery of nitrogen derived from some ammonium salts and nitrates was 100% by two-step measurement with elemental analyzer. By the analytical method investigated in this report, carbon and other elements in suspended particulates(S.P) collected at an urban area in Seoul were measured. There was a good correlation between total nitrogen in SP measured by elemental analyzer and nitrogen estimated form ammonium ions and nitrate ions in SP. The nitrogen from these ions accounts for 80% of the total nitrogen. It is further suggested that the residue(20%) of the total nitrogen is attributed to the other nitrogeneous compounds.

• 한국환경과학회지
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• 제13권9호
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• pp.799-806
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• 2004

The filtration tests were made in cell with a low concentrated suspension. The suspension with a concentration of $C_{M}$=1.14～2.67$\cdot$$10^{-3}$ g/g consists of paper paint and water. The particles in the suspension have a particle size x<1${\mu}m$. The used depth filters consists of glass fibres, which are coated by polymer. The filtration in depth filters accorded in different mechanism, which were explained by physical models. The model which would be allows to make a promise of the filtration reaction. This filter media allows to get a high filtration time and a good separation rate. The Particle distribution is measured by a photon correlation spectroscopy(PCS). PCS measures particle sizes 0.03 ${\mu}m$${\mu}m$ in the suspension. The filtered suspension has a very low concentration Co{\le}5{\times}10_{-4}$ g/g of solid in sample. The PCS also informs us about the number of the particles in the suspension. The makes it possible to calculate the concentration of the in sample.

• 한국환경과학회지
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• 제20권4호
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• pp.493-500
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• 2011

This study investigates the relationship between Asian dust and asthma disease in Seoul, using data of Asian dust occurrences and the number of treatments for asthma between 2005 and 2008. The data include the number of treatments for asthma on the basic day paired with the average number of treatments for asthma on the compared days. The compared day is defined by the day of no Asian dust in same month and day of the week as the basic day, when Asian dust occurs. Also, the basic day is expanded to the day after three days from the day of Asian dust. The paired two sample t-test for the number of treatments for asthma on the basic day and the compared days revealed that the Asian dust occurrences are correlated with the asthma disease. The number of treatments for asthma is significantly increased on the one and two days after Asian dust occurs. On the other hand, there's no significant difference in the number of treatments for asthma between the days of Asian dust occurrence and the days of no Asian dust, which implies that people usually try not to go out when Asian dust occurs.

• 한국환경보건학회지
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• 제10권1호
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• pp.67-77
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• 1984

Going to the studies on parasite control carried out in the past. Infection rate among the rural population is contineously decreasing, however, it is still high in Korea. The most important reason for this high infectious rate is the use of manure as fertilizer. This study was aimed at finding the relationship between the infection rate and manure through analizing 83 samples of soil collected from Sa Am-Ri, Kangwon-do in June and July, 1983. The major findings of the study are as follows: 1. 60 cases out of the total sample were carry in at least one or more parasitic eggs, thus revealing 72.3% of positive rate. 2. A total number of 131 parasitic eggs were detected from total sample with an average of 1.6 eggs per 10 g of soil. 3. Asearid eggs more frequently appeared than other parasitic eggs occupying 68.7% or 1.2 eggs in average per 10g of soil. 4. There was revealed positive relationship between infectious rate and frequency of use of manure. (P > 0.05). 5. Infectious rate and average number of parasitic eggs detected were less in the fertilizer mixed with manure and ash than in the soil where only manure was used. (P > 0.05).