• 한국세라믹학회지
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• 제23권3호
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• pp.94-98
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• 1986

Infrared has been used in determination of water in magnesium metaphosphate glasses. The method consisted of measuring the weight loss and the variation in absorption coefficient at 3, 200$cm^{-1}$. The molar absorptivity of water in magnesium metaphophate glasses was found to 76.9ι$mol^{-1} cm^{-1}$ Using the value for $\varepsilon$, A and Δ$\upsilon$H of the hydroxyl band in the spectra of magnesium metaphosphate. The molar absorptivity of the hydroxyl absorption band at 3, 3130-2, $925cm^{-1}$ in the spectra of MgO.$P_2O_5$ system glasses could be computed. And a variation of molar absorptivity against the MgO/P2O5 ratio has not been shown regulation.

• Asian-Australasian Journal of Animal Sciences
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• 제5권3호
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• pp.559-561
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• 1992

Three strains each of L. bulgaricus and S. thermophilus isolated from indigenous dahi were examined for their rate of acid production and corresponding pH values in skim milk medium incubated at $40^{\circ}C$. No significant increase in titrable acidity or decrease in pH were recorded from initial period up to 2nd hour in both the strains. Following this period, however, there was a continuous increase in titrable acidity and a decrease in pH value in the milk for all the tested strains. Further it was observed that there was a variation among these strains for their acid production rate. High rate of acid production was recorded for the L. bulgaricus as compared to S. thermophilus. The results further, suggested that efforts should be made to select a proper pair of L. bulgaricus and S. thermophilus according to their rate of acid production, at a particular temperature in order to produce a good quality product.

• 한국물환경학회지
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• 제29권2호
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• pp.176-183
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• 2013

The variation of the stable region of arsenic compounds in aqueous environment with temperature has been investigated by constructing the Pourbaix diagram of arsenic at different temperatures. The standard potential corresponding to the boundary between arsenic compounds with different charge valence was estimated to be decreased with temperature, which means the stability of arsenic compound with +5 charge valence increases. The distribution diagram of the most highly oxidized arsenic compound showed that arsenic acid is formed at higher pH and arsenate is generated at lower pH as temperature rises. The aquatic toxicity due to arsenic compounds was considered to be decreased with temperature in the neutral pH condition based on the $LD_T$ value defined in this study.

• Journal of Nutrition and Health
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• 제15권1호
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• pp.39-46
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• 1982

Nitrate accumulated in vegetables can, via $NO_2$ during storage and after their ingestion, cause the formation of methemoglobin and many of which are carcinogenic in human body. Especially such vegetables with the highest consumption in Korea as chinese cabbage and raddish frequently showed that high contents of nitrate and nitrite could accumulate. Therefore, pH and the content of nitrate and nitrite of Korean pickles made of upper vegetables, viz, Baiechu Kimchi, Yulmookimchi and Kakdooki were estimated during storage at the conditions of $5^{\circ}C$ and $25^{\circ}C Storage at $25^{\circ}C$ generally led to the more rapidly than that at $5^{\circ}C$. But changes of nitrite level showed very low variation in all tested Kimchi.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제3권3호
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• pp.159-167
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• 1999

This study performed experiments for measuring corrosion potential and current density variations in the polarzation curves of polyvinylchloride. The results were examined to identify particular influences affectingthe corrosion potential such as temperature, pH, enzyme, and salt. The lines representing active anodic dissolution were only slightly shifted in the potential direction by temperature, pH, enzyme and salt. The Tafel slope for the anodic dissolution was determined using the polarization effect with varying conditions. The slope of the polarization curves describing the active-to-passive transition region was noticeably shifted in the potential direction. In addition, using the variation in conditions, the best temperature and pH were determined for the corrosion rate, and resistance of corrosion. The second anodic current density peak and maximum passive current density were designated as degraded(IP/I0). The value of IP/I0 was used in measuring the extent of the degradation of the polyvinychloride. The potentiodynamic parameters of the corrosion were obtained using a Tafel plot.

• 한국세라믹학회지
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• 제35권2호
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• pp.107-114
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• 1998

ZnO powder as phosphor was prepared by precipitation method with zinc acetate and ammonia solution and the size and shapes of precipitates were examined with variation of pH and concentration of solution. Its cathodoluminesence properties was evaluated with various heat tratment condition. Optimum con-dition for uniform precipitates was 11.8 of pH and 0.4M of concentration. ZnO:Zn phosphor was obtained by heat treatment of precipitates in reduction atmosphere using ZnS powder. With addition of 20wt% ZnS and 1 hour firing at 1000$^{\circ}C$ the highest cathodoluminescence was obtained.

• 한국환경보건학회지
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• 제12권2호
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• pp.67-74
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• 1986

The study was carried out to investigate for the property of Bacillus strains, on the native growthed microflora in Korean native soybean paste, and Bacillus strains of the high enzyme producing, were selected and identificated, from the microflora, that is, identificated Bacillus strains beared resemblance to B. subtills, on the colony, appearance was pellicle, surface's spreading, color creamy-thin browned, colony elevation flated, and edge lobated, the identfficated B. subtills strain named for the B. subtilis SCF. For the protease activity of B. subtilis SCF, according to the variation with pH, the pH stability was pH 7~8, and on the its protease activity, optimum temperature was 40$\circ$C, on the other hand, temperature of the highest stability of the protease was 50$\circ$C.

• 한국환경과학회지
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• 제19권3호
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• pp.261-267
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• 2010

The variation of assimilable organic carbon(AOC) concentration at each condition of ozonation was investigated using a model water and drinking water resource. AOC concentration of model raw water and drinking water resource tended to increase at low ozone dose. The maximum AOC concentration was detected when the residual ozone begin to be measured. Also, the AOC concentration increase at pH 8 compared to both pH 6 and 7 while that for pH 9 decreased rapidly. The removal characteristics of trihalomethane formation potential(THMFP) by ozonation was also investigated. Unlike the trend of AOC, the THMFP concentration never increased by ozonation but decreased even at low ozone dosage. From these results, the ozone dosage would be effective to simultaneously decrease both AOC and THMFP.

• 한국표면공학회지
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• 제24권1호
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• pp.1.2-1.2
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• 1991

The formation of managanese ferrite has been performed to investigate some properties according to the variation of compositions, pH, current density by electrolysis. It has been found that the amount of oxidized weight of anode were increased with increasing current density. The amount of oxidized weight of anode were most in pH10. As the result of X-ray diffraction Mn Fe2O4 crystal composition in pH13. When the particles of Mnx Fe3-x O4 were heated at 30$0^{\circ}C$, it has been shown typical MnFe2O4(JCPDS Card No. 10-319) in X-1 composition. As the result of SEM observation, the size of MnFe2O4 particles were about 0.1$\mu\textrm{m}$, the shape of particles were spherical type. According to the above mentioned experimental condition, 0.1-0.5$\mu\textrm{m}$ sub-micron particles of manganese ferrite were formed from the wasted manganese dry cell, through washing longrightarrow reduction longrightarrow electrloysis.

• 생명과학회지
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• 제9권5호
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• pp.590-595
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• 1999

The objectives of this research were to estimate variation characteristics of TOC, UV-254 and NH4+-N, etc, if odorous generated algaes flowed into water treatment plant and they contacted with ozone known as typical advanced treatment. It was estimated that pH decreased from initial 7.4 to 2.1 after ozone contact 100min. pH declined to early 10min. suddenly and then pH drop did almost occur. TOC and UV-254 continued to decrease with passed time of ozone contact. NO3--N concentration was much higher than NH4+-N and NO2--N for whole test period. Because ozone oxidized organic matters as various kinds of ion material and ion intensity of sample was extended, conductivity showed high as passed time of ozone contact. Owing to ozone oxidation of algae, color did almost disappear after ozone contact 20min.