• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.323-335
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• 2019

Rice is sensitive to day-length and short-day plants. It has a characteristic that the photosensitivity response required for flower bud differentiation decreases under long-day conditions. To identify critical photoperiod required for flower bud differentiation of major cultivation rice varieties, the average temperature was fixed at 28 ℃, and the day length was set at 12 hours and 10 minutes intervals from 13 hours to 14 hours 30 minutes. The critical photoperiod for each cultivar was set to day-length, where the daily cumulative response [(X_{(Critical Photoperiod)}-Y_{(Set day-length)})/(X_{(Critical Photoperiod)}-12:00_{(Optimal Day-length)}) × (28.0_{(Set Temperature)}-10_{(Minimum Temperature)})/(29.2_{(Maximum Temperature)}-10_{(Minimum Temperature)})] was the same for each day-length conditions. The flower bud differentiation time of all varieties was 32 days before heading at the average temperature of 28 ℃ conditions. The critical photoperiod of the early maturing type, such as Woonkwang, Odae, Koshihikari, Jopyeong, were 19:20, 18:14, 18:58, 17:30, respectively. Medium maturing type, such as Daebo, Haiami, Samdeok, were 16:08, 16:15, 16:55, respectively. Mid-late maturing type, such as Saenuri, Sindongjin, Chucheong, Samkwang, Ilpum, Saeilmi, Hwangkeumnuri, Dongjinchal, Ilmi, Hopum, Yeonghojinmi, were 15:58, 15:56, 16:36, 16:44, 15:35, 16:26, 15:33, 16:20, 16:29, 16:13, 15:41.

• Economic and Environmental Geology
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• v.43 no.6
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• pp.555-564
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• 2010

Remediation process by using the bio-carrier (beads) with dead Bacillus sp. B1 and polysulfone was investigated for heavy metal contaminated groundwater. Sorption batch experiments using the bio-carrier were performed to quantify the heavy metal removal efficiencies from the contaminated solution. The analyses using SEM/EDS and TEM for the structure and the characteristic of precipitates on/inside the beads were also conducted to understand the sorption mechanism by the bio-carrier. Various amounts of freeze-dried dead Bacillus sp. B1 were mixed with polysulfone + DMF(N,N-dimethylformamide) solution to produce the bio-carrier (beads; less than 2mm in diameter) and 5% of Bacillus sp. B1 in the bio-carrier was optimal for Pb removal in the solution. The removal efficiency ratings of the bio-carrier for Pb, Cu and Cd were greater than 80% after adding 2g of bio-carrier in 50ml of aqueous solution (<10mg/L of each heavy metal concentration). Reaction time of the bio-carrier was very fast and most of the sorption reaction for heavy metals were completed within few hours. Batch experiments were duplicated at various pH conditions of aqueous solutions and Cu and Pb removal efficiencies highly maintained at wide pH ranges (pH 2-12), suggesting that the bio-carrier can be useful to clean up the acidic waste water such as AMD. From SEM/EDS and TEM analyses, it was observed that the bio-carrier was spherical shape and was overlapped by many porous layers. During the sorption experiment, Pb was crystallized on the surface of porous layers and also was mainly concentrated at the boundary of Bacillus sp. B1 stroma and polysulfone substrate, showing that the main mechanism of the bio-carrier to remove heavy metals is the sorption on/inside of the bio-carriers and the bio-carriers are excellent biosorbents for the removal of heavy metal ions from groundwater.

• Applied Biological Chemistry
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• v.39 no.3
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• pp.172-176
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• 1996

Effect of culture conditions such as pH, temperature, agitation speed and oxygen transfer rate on xylitol production from xylose by Candide parapsilosis ATCC 21019 mutant was investigated in a jar fermentor. The initial concentration of xylosr was fixed at 50 g/l in this experiment. When pH was increased, cell growth and xylose consumption rate were increased, but maximum xylitol production was shown in the range of pH 4.5 and 5.5 with a yield of 0.68 g/g-xylose. The optimal temperature for xylitol production was determined to be $30^{\circ}C$. Considering the importance of dissolved oxygen tension, for xylitol production, the effect of oxygen transfer rate coefficient $(k_La)$ on fermentation parameters was carefully evaluated in the range of $20{\sim}85\;hr{-1}\;of\;k_La$ (corresponding to $100{\sim}300$rpm of agitation speed). The xylitol production was maximized at $30\;hr^{-1}\;of\;k_La$(150 rpm). A higher oxygen transfer rate supported better cell growth with lower xylitol yield. It was determined that maximum xylitol concentration, xylitol yield and productivity was 35.8 g/l, 71.6% and $0.58\;g/l{\sim}hr^{-1}$, respectively, at $30\;hr^{-1}\;of\;k_La$ In order to further increase xylitol productivity, ferementation using the concentrated biomass(20 g/l) was carried out at the conditions of pH 4.5, $30^{\circ}C$ and $30\;hr\;1$ of oxygen transfer rate. The final xylitol concentration of 40 g/l was obtained at 18 hours of culture time. From this result, it was calculated that xylitol yield was 80ft on the basis of xylose consumption and volumetric productivity was $2.22\;g/l{\sim}hr$ which was increased by $3{\sim}4$ fold compared with $0.5{\sim}0.7\;g/l-hr$ obtained in a normal fermentation condition.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.1
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• pp.11-17
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• 2003

As a pan of a study on effective use of seafood processing by-products, such as cuttle bone as a calcium source, we examined on the kind of organic acid (acetic acid and lactic acid), reaction concentration (mole ratio of calcium to mole of organic acid), reaction temperature $(20\~60^{\circ}C)$ and reaction time (6$\~$24 hours) as reaction conditions for the solubility improvement of cuttle bone powder. The high soluble cuttle bone powder was also prepared from the optimal reaction conditions and partially characterized. From the results on examination of reaction conditions, the high soluble cuttle bone powder was prepared with 0.4 in mole ratio of a calcium to mole of a acetic acid at room temperature for 12 hours, Judging from the patterns of IR and X-ray diffraction, the main component of the high soluble cuttle bone powder was presented as a form of calcium acetate, and a scanning electron micrograph showed an irregular form. The soluble calcium content in the high soluble cuttle bone powder was $5.3\%$ and it was improved about 1,380 times compared to a raw cuttle bone powder. For the effective use of the high soluble cuttle bone powder as a material for a functional improvement in processing, it should be used after the calcium treatment at room temperature for about 1 hour in tap water or distilled water. from these results, we concluded that it is possible to use the high soluble cut시e bone powder as a material for a functional improvement in processing.

• Pediatric Infection and Vaccine
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• v.18 no.2
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• pp.109-116
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• 2011

Purpose : Pneumococcus is one of the most important causes of invasive infection through the childhood period. In January 2008, the Clinical and Laboratory Standards Institute (CLSI) published revised penicillin breakpoints for Streptococcus pneumoniae and penicillin susceptibility rates of S. pneumoniae increased in Korea. This study was performed to determine the probability of oral amoxicillin for the empirical treatment achieving bactericidal exposure against pneumococcus using pharmacodynamics model. Methods : Twenty-three isolates of pneumococci were subjected to determine minimum inhibitory concentration (MIC) for ${\beta}$-lactams and macrolide. For the ${\beta}$-lactams, exposure of fT >MIC (time that free drug concentrations remain above the MIC) for 50% of the administration interval have determined the probability of target attainment (PTA), and regimens that had a PTA >90% were considered optimal. An analysis was performed by applying MIC of 23 isolates to a 5000-patient Monte Carlo simulation model. Results : Among 23 isolates from healthy children, 7 (30.4%) isolates were MIC ${\leq}$1.0 ${\mu}g$/mL and 19 (82.6%) were MIC ${\leq}$2 ${\mu}g$/mL for amoxicillin. Amoxicillin 40 mg/kg/day achieved PTA >90% at MIC ${\leq}$1.0 ${\mu}g$/mL but PTA decreased to 52% at MIC 2 ${\mu}g$/mL, whereas amoxicillin 90 mg/kg/day can predict 97% of PTA at MIC 2 ${\mu}g$/mL. Overall, oral amoxicillin 90 mg/ kg/day for the empirical treatment against pneumococcus can expect more successful response in Korean children. Conclusion : Considering the resistantce pattern of pneumococci in Korean children, we estimate that oral amoxicillin 90 mg/kg/day will provide a pharmacodynamic advantage for the empirical treatment against pneumococcus. And low dose amoxicillin or macrolide are expected to have higher chance of treatment failure than high dose oral amoxicillin.

• Korean Journal of Food Science and Technology
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• v.50 no.1
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• pp.44-54
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• 2018

To maintain the best quality of kimchi during long-term storage, we developed a fermentation storage mode for the kimchi refrigerator. The optimal kimchi fermentation temperature was determined to be $6^{\circ}C$ with fermentation time of 4-7 days in winter and 3-5 days in spring and fall. Based on these results, the fermentation storage mode conditions were programmed to consist of a fermentation temperature of $6^{\circ}C$ and fermentation times of 111 h in winter and 58 h in spring/fall. When kimchi was stored under the developed fermentation storage mode conditions, the total acidity of kimchi was almost the same as that of the control kimchi (stored $-2-\;-1^{\circ}C$ for 12 weeks). However, the number of lactic acid bacteria (LAB) and Leuconostoc sp. in kimchi were higher ($10^1-10^2CFU/mL$) than those in the control kimchi during storage. In addition, kimchi fermented and stored under the fermentation storage mode clearly received higher scores for overall preference than the control kimchi.

• Journal of Food Hygiene and Safety
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• v.3 no.4
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• pp.225-232
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• 1988

To improve the storage method for Kimchi, optimal ripening Kimchi was irradiated with doses of 1,3,5 kGy Co-GO gamma radiation, followed by the microbiological, physicochemical and sensory evaluations during storage at $5^{\circ}C$. 1. Total aerobic count increased in the beginning of storage and then decreased slowly as the number of total lactobacilli (anaerobe) increased. The above total aerobic and lactobacilli were reduced by 1 to 3 log cycles with irradiation and at the 90th day after storage the number of total lactobacilli remained $1.30{\times}10^{8}\;per\;ml$ in3 kGy irradiated group. Irradiation treatment at 3 kGy sterilized coli forms and molds contaminating the sample as the level of $2.0{\times}10^{4}\;per\;ml\;and\;5.4{\times}10^{2}\;per\;ml$, respectively and no apparent growth was observed in both control and 1 kGy irradiated groups after 20 days of storage. The population.of yeast, $3.5{\times}10^{3}\;per\;ml$ initially, in, creased steadily during Kimchi storage and at 90 days of storage the number was shown to be $5.6{\times}10^{4}\;per\;ml\;and\;6.5{\times}10^{2}\;per\;ml$ in control and 3 kGy irradiated groups, respectively. 2. In the physicochemical changes during Kimchi storage, pH, acidity and volatile acid of non-irradiated control at the 45th day after storage were 4.0,0.7% and 0.066%, while those of 3 kGy irradiated group were 4.2, 0.59 and 0.06% at the 90th day of storage, respectively. The reducing sugar content of all stored samples changed inversely total acidity content, indicating irradiation delayed the changes of them. The amount of aseorbic acid decreased gradually with the storage time and irradiation dose increase. Textural parameters of 3 kGy irradiated group were superior to those of other groups at the latter stage of storage. 3. Sensory evaluations showed that 3 kGy irradiation was the optimum dose level to extend tite shelf-life of Kimchi more than two months as compared to control.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.694-705
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• 2017

The aim of this study was to isolate and identify marine bacterium with anti-methicillin-resistant Staphylococcus aureus (MRSA) activity, and to purify the anti-MRSA compound, as well as to determine its activity and synergistic effects. Among the marine bacteria isolated in this study, the YJ-1 isolate had the strongest anti-MRSA activity. The YJ-1 isolate was identified on the basis of its biochemical characteristics and an analysis of 16S rRNA gene sequences. The YJ-1 isolate showed over 99.2% homology with Pseudomonas stutzeri, and was designated as a Pseudomonas sp. YJ-1. The optimal culture conditions were $25^{\circ}C$ and initial pH 7.0. For the purification of the anti-MRSA compounds, the YJ-1 was cultured in Pa PES-II medium, and the culture filtrates were extracted by ethyl acetate, hexane, and 80% MeOH. The 80% MeOH fraction was separated by a $C_{18}$ ODS column, silica gel chromatography and a reverse phase HPLC, to yield three anti-MRSA agents, the MR1, MR2, and MR3 compounds. When the MR1 compound of $250{\mu}g\;mL^{-1}$ concentration was applied to the MRSA cells, over 95% of bacterial cells was killed within 48 hr. Compared with vancomycin and ampicillin, the MR1 compound showed significant anti-MRSA activity. In addition, the anti-MRSA activity was increased by dose and time dependent manners. Furthermore, the combination of an MR1 compound with vancomycin produced a more rapid decrease in the MRSA cells than did the MR1 compound alone. Taken together, our results suggest that the Pseudomonas sp. YJ-1 and its anti-MRSA compounds could be employed as a natural antibacterial agent in MRSA infections.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.1
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• pp.97-103
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• 2015

This study investigated changes in phenolic contents of different parts of Rhus verniciflua Stokes (RV) according to extraction conditions. Bark and xylem parts of RV were extracted at 80, 100, 120, 140, and $160^{\circ}C$ for 1, 3, and 5 h, respectively. Major phenolic compounds (gallic acid, protocatechuic acid, fustin, fisetin, sulfuretin, and butein) of RV were analyzed. The gallic acid, fisetin, sulfuretin, and butein contents significantly increased as extraction temperature increased. Protocatechuic acid and fustin contents increased as increasing extraction temperature to $120^{\circ}C$ and decreased afterward. The gallic acid, protocatechuic acid, and butein contents of bark were higher than those of xylem extracts. The optimal extraction conditions of gallic acid, protocatechuic acid, fustin, fisetin, sulfuretin, and butein were $160^{\circ}C/3h$ (380.22 mg%), $120^{\circ}C/1h$ (9.25 mg%), $100^{\circ}C/3h$ (206.97 mg%), $140^{\circ}C/5h$ (93.84 mg%), $140^{\circ}C/5h$ (16.07 mg%) and $160^{\circ}C/5h$ (1.49 mg%), respectively. These results suggest that the optimum extraction temperature and time considering RV extraction yield and cost are $140^{\circ}C$ and 3 h, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.3
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• pp.352-359
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• 2016

White bread added with brown rice fiber was prepared by addition of 0.005, 0.010, 0.015, and 0.020% hemicellulase. Effects on product quality and sensory evaluation were examined. There were no significant differences in pH of dough before the 1st fermentation among the experiments. Dough made by addition of hemicellulase had a significantly higher pH after the 1st fermentation compared to the control group, whereas pH of bread had reverse effects. Fermentation power of dough expansion increased as incubation time increased. Addition of hemicellulase to samples significantly increased specific volume, baking loss, and water activity compared to the control sample. Moisture content was the lowest upon addition of 0.020% hemicellulase. For color, lightness was the highest in the control bread samples, greenness of the 0.015% addition sample was the lowest and yellowness of the 0.005% addition sample was the highest. For textural characteristics, hardness, gumminess, and chewiness were maximum in the control group. Cohesiveness and springiness were not significantly different between the samples. In the sensory evaluation, color, flavor, bran flavor, bitterness, astringency, and coarseness were not significantly different among the samples. Softness and overall acceptability were highest at the 0.020% addition level but lowest at the 0.010% level. The results indicate that addition of 0.020% hemicellulase to brown rice fiber white bread is optimal for quality and provides products with reasonably high overall acceptability.