• 수산해양기술연구
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• 제17권2호
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• pp.77-83
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• 1981

하천 오염에서 문제시되고 있는 유기오염 물질인 PCP 와 DDT의 환경기준을 평가하고 담수어 어종간의 독성에 대한 저항성을 연구하였다. 각 어종에 대하여 24, 48, 72 및 96시간의 TL sub(m) 값을 산출하였던 바 오염물질에 대한 저항성은 오염물질의 성상에 따라 상이한 양상을 보여주었다. 실험한 10종의 담수어중 PCP 및 DDT에 저항성이 약한 어종은 N. Chrysophekadion으로 96 h-TL 하(m) 값은 0.065mg/l 과 0.0044mg/l으로 각각 나타났으며 PCP에 저항성이 강한 어종은 T. nilotica로서 96 h-TL 하(m) 값은 0.264mg/l이었으나, DDT에 대해서는 C. Siamensis로서 96 h-TL 하(m) 값은 0.0133mg/l로 평가되었다.

• 한국식품영양학회지
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• 제34권4호
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• pp.390-397
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• 2021

The purpose of this study was to investigate at how the quality of citron changed during storage as a result of the browning inhibitor treatment. In the browning inhibitor treatment, Vit.C, Vit.C+NaCl, Vit.C+NaCl+CD substances were used. As a result of investigating the browning degree, Vit.C+NaCl+CD showed the lowest value of 0.76 when stored for 12 weeks. The 𝚫E of the chromaticity value indicated that significant color change occurred when the value was high. As the Vit.C+NaCl+CD mixture showed the lowest value of 46.01 at 25℃, it was found that browning did not occur much compared to other treatments. The change in polyphenol oxidase (PPO) activity of citron increased as browning progressed. Among the browning inhibitor solutions, Vit.C+NaCl+CD solution showed the lowest value 118.8 u/g at 25℃ after 12 weeks. Based on these findings, it seems that CD mixing solution can be used as a citron browning inhibitor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1433-1435
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• 2001

The mechanical and phase transformation of the cold isostatically pressed $\beta$-SiC ceramic were investigated as a function of the sintering temperature. The result of phase analysis revealed 6H, 4H, 3C and phase transformation between 3C and 4H showed over 2000$^{\circ}C$ and the $\beta$ ${\rightarrow}$ $\alpha$ phase transformation was in saturation at 2200$^{\circ}C$. The relative density and the mechanical properties of $\alpha$-SiC ceramic was increased with increased sintering temperature. The flexural strength showed the highest value of 230 MPa at 2200$^{\circ}C$. This reason is because crack was propagated through surface flaw. The fracture toughness showed the highest value of 4.2 $MPa{\cdot}m^{1/2}$ at 2200$^{\circ}C$.

• Journal of Biosystems Engineering
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• 제26권2호
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• pp.155-162
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• 2001

The greenhouse heating system with heat pump was built for development of simulation model and validation. The computer simulation model for the system to predict temperature of air and soil and moisture content of soil in the greenhouse were developed, and its validity was justified by actual data. From the analysis of experimentally measured data and the simulation output, following results were obtained. 1. The expected values of inside air temperature for the heating system with heat pump were very much close to the experimental values. 2. In the heating system with heat pump, the expected values of day time surface temperature of soil by computer simulation were very much similar to the measured values, but those of night time were higher than the measured value by at most 2.0$\^{C}$. 3. The simulation model predicted temperature of greenhouse film as of 1$\^{C}$ below than the mean value of ambient air and greenhouse air temperature. 4. Heat loss value of daytime was found to be larger than that of nigh as much as 1.3 to 2.3 times for the heating system with heat pump. 5. In the heating system with heat pump, when the lowest ambient temperature was -8$\^{C}$∼-7$\^{C}$ the air temperature of greenhouse was 5$\^{C}$∼6$\^{C}$, thus the heat pump heating system contributed in greenhouse heating by 13$\^{C}$.

• 한국주조공학회지
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• 제16권2호
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• pp.109-115
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• 1996

Effect of various austempered structures on fracture characteristics of C/V graphite cast iron has studied. The tensile strength and hardness reached the maximum value of 971.4MPa and HB302 at the austempering temperature of $250^{\circ}C$, respectively. As the austempering temperature increased, the amount of retained austenite increased from 18% to 22, 29%, while $K_{IC}$ values ranged from the value of $65MPa{\cdot}m^{12} to 70MPa{\cdot}m^{1/2}, 66MPa{\cdot}m^{1/2}. This fact that $K_{IC}$ value was not sensitive to the increase of the amount of the retained austenite was that $K_{IC}$ was dependent on the matrix structure in lower bainitic matrix, while dependent on the notch effect from C/V graphite shape in upper bainitic matrix. Fractured surfaces showed a ductile fracture pattern at $300^{\circ}C$. Very large coalescence by C/V graphite and relatively small voids by spheroidal graphite were observed.

• Applied Biological Chemistry
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• 제20권1호
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• pp.101-104
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• 1977

Geotrichum candidum이 분비한 lipase를 인산완충용액 중에서 열처리하여 열불활성 곡선을 얻었다. $50^{\circ}C$에서 lipase의 열 불활성 곡선은 고온의 경우와는 달리 일차 반응 속도법칙을 따르지 않았고 고온의 경우에는 일차 반응을 따랐다. $60^{\circ}C$에서의 엔탈피, 엔트로피 및 깁스 자유 에너지의 변화는 각각 120.4 kJ/mol, 73.0 J/mol.K 및 96.9 kJ/mol이었다. 열 불활성 곡선에서 얻은 Geotric hum candidum lipase의 z-value는 $19^{\circ}C$로 pancreas나 우유 중에 존재하는 lipase의 z-value보다 훨씬 큰 값을 나타낸다. 환경인자의 영향으로는 lecithin과 linoleic ac를 첨가하여 열처리 하였는데 실험에 사용한 계면활성제의 농도에서는 별다른 큰 영향을 미치지 않았다.

• 동아시아식생활학회지
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• 제10권6호
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• pp.507-513
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• 2000

This study was conducted to investigate the shelf life of beef stored in antimicrobial pottery during 12days storage at 4'C and Five kinds of antimicrobial potteries were prepared with antimicrobial materials such as TiO$_2$, Ag (NO$_3$)$_2$, Cu(NO$_3$)$_2$ and Zn(NO$_3$)$_2$. In changes of color during storage, Hunter's L- and b-value of beef were not changed, but Hunter's a-value was low significantly. The pH of beef meats were low at 6 days, but were added from 6 days. TBA value of beef in "A" pottery containing TiO$_2$ 1% and "C" Pottery containing TiO$_2$ 0.5%, Cu(NO$_3$)$_2$ were lower than "B", "D" and "I" pottery. VBN contents of beef in "A", "B", "C", "D" and "I" Pottery stored during 12 days were 9.8, 12.5, 9.3, 11.9 and 13.7mg%, respectively. In changes of total plate count of beef during storage at 4$^{\circ}C$, the antimicrobial activity of "A" and "C" pottery were superior.g storage at 4$^{\circ}C$, the antimicrobial activity of "A" and "C" pottery were superior.ttery were superior.

• 한국경영정보학회:학술대회논문집
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• 한국경영정보학회 2007년도 추계학술대회
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• pp.527-532
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• 2007

Differentiation strategies have been suggested as the critical sources of competitive advantage in B2C industry where customers can switch internet shopping mall with one click with virtually no transaction cost. Indeed, competition on low pricing cannot be a viable strategy in B2C industry. Moreover, cultivating customer loyalty to attain profitability is still a challenging task for most internet shopping mall. In this study, we provide empirical analysis results on key managerial variables that indicate the difference between the product categories in terms of customer perception on relative value importance. We first identified comprehensive managerial variables and organized them in terms of customer decision stage. Next, with reference to extant literatures on product characteristics based e-commerce strategy, hypotheses are developed to formalize the customer value differences on the key managerial variables. Empirical testing results indicated that there are significant differences on customer perceived value of the key managerial variables between the product groups. The findings provide useful insight for further study on e-commerce differentiation strategy.

• 한국식품저장유통학회지
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• 제5권1호
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• pp.41-47
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• 1998

Physicochemical properties and microbiological quality chanties were investigated on mixed fruit and vegetable juices (apple, carrot and cucumber) stored at 4$^{\circ}C$ without pasteurization(NT), with light piasteurization (LP; 66$^{\circ}C$, 10 sec) and with full pasteurization(FP; 90$^{\circ}C$, 60 sec). Effects of ultrafiltration (UF) on the changes during storage were also examined. pH, viscosity, a-value and b-value remained relatively constant and all samples revealed Newtonian characterisitics. Total acidity and turbidity tended to increase slightly; however, total vitamin C content and L-value slowly decreased during storage up to about 2 months. During the first 4 weeks storage, soluble solids content slowly increased and then decreased. Mold and Yeast and Bacteria were not detected in LP, UP and UF treated samples during storage studied; however, E. coli were detected after 24 days storage. No distinctive storage effects were found among samples prepared; however, ultrafiltration had a considerable effect on the color and soluble solids content of mixed fruit and vegetable juice.

• 한국조리학회지
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• 제24권2호
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• pp.79-86
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• 2018

The purpose of current study was to evaluate the oxidative stability of soybean oil after frying according to storage temperature. The soybean oil after 10 times deep fat frying with potato sticks (10% w/w of oil) were stored during 10 days at 30, 60 and $90^{\circ}C$ and chemical properties were determined. The acid value and peroxide value were the highest and the iodine value were the lowest when the oil stored at $90^{\circ}C$. Expecially, the production rate of peroxide was fast at over $60^{\circ}C$. According to the results, frying oil should not be stored for more than 6 days at $30^{\circ}C$ after use. Since the oil used had already produced unstable peroxides, oxidation could proceed relatively quickly even at low temperatures. Therefore, it is desirable to keep the used oil at a temperature as low as possible.