• Korean Journal of Veterinary Research
• /
• v.37 no.1
• /
• pp.185-188
• /
• 1997

전남대학교 수의과대학에서는 조류 blue-green algae를 먹이로 하여 간질의 중간숙주인 애기물달팽이를 실험실에서 유지시켜 왔으나 조류의 배양에 어려움이 많아서 보다 간편하면서 달팽이의 번식에도 좋은 방법을 고안하고자 노력하였다. $28.5{\times}17{\times}18cm$ 크기의 유리수조에 모래를 1.5cm 높이로 깔고 10개의 꼬막껍질을 그 위에 올려놓은 다음 4리터의 증류수를 부어넣었다. 야외에서 채집한 달팽이의 난괴를 부화시켜 얻은 0.63cm 크기의 어린 달팽이 45마리를 세 그룹으로 나누어 세 개의 수조에서 $20^{\circ}C$의 온도를 유지하면서 사육하였고 먹이로 상추잎을 넣어주었다. 매주 수조바닥의 물 $2{\ell}$를 흡인하여 갈아주면서 상추잎을 바꿔넣었고, 계속해서 공기를 통과시켜 산소를 공급하였다. 이와 동일한 방법으로 실험실에서 조류로 사육하던 17대의 달팽이를 사육하여 그 성적을 비교하였던 바 야외에서 채집한 달팽이의 성장률이 실험실에 적응된 것들에 비하여 약간 떨어졌으나 생존율이나 산란율에서는 큰 차이가 인정되지 않았다. 그래서 1년이 넘도록 이 방법으로 달팽이를 사육하면서 간질의 피낭유충을 생산하고 있다. 꼬막껍질은 서서히 분해하면서 달팽이의 각을 형성하는 물질을 제공하여 생존율을 높게 한 것으로 생각된다. 그리고 수조를 햇볕이 드는 창문 가까이에 놓아두었기 때문에 조류가 자생하여 적은 양이나마 달팽이의 먹이가 되었을 것으로 보인다.

• Resources Recycling
• /
• v.7 no.3
• /
• pp.17-26
• /
• 1998

A study on the recovery of silver and nitric acid in the liquid waste resulted from the mediated electrochemical oxidation(MEO) process was conducted. The removal of silver in the concentrated nitric acid solutions was carried out by the electrodeposition. The removal efficiency more than 98% could be obtained in nitric acid concentrations less than 3 M with the current efficiency of nearly 100%. The experimonts on the evaporation for the recovery of nitric acid were performed as well. At the evaporation factor of 25., the degree of nitric acid recovery in 3.5 M nitric acid solution containing 0.5 to 1.0 mol% NaNO, was 80~90% resulting in 2.8~3.1 M nitric acid. The design factors and operating conditions of the distillation tower were analyzed by using MEH model derived by Maphtali-Sandholm with the throughput of 4 kg/hr for the enrichment of dilute nitric acid solution recovered by evaporation to reuse in the MEO process. The distillation column composed of eleven theoretical stages having the overall tray efficiency of 70% are needed to obtain 1.03 kg/h of 12M nitric acid and 2.97 kg/h of water with feed being introduced to the column at tray 6 from the bottom at the reflux ratio of 0.25, the reboiler with the heat load of 2.7 kW, and the condenser with the cooling load of 0.5 kW.

• KSBB Journal
• /
• v.23 no.6
• /
• pp.525-528
• /
• 2008

In order to compare the germination and growth rate of the sprouts soaked in highly concentrated oxygen water, it with specific amounts of oxygen dissolved was produced in a high pressure reactor by pressuring oxygen. The sprouts were observed after being soaked in $20^{\circ}C$ oxygen water with 20, 30, 40, 50 ppm of oxygen dissolved each. Results of ten days later indicate that the final germination rate of the sprout soaked in 50 ppm oxygen water was $24.6{\sim}28.6%$ higher than that of the sprout soaked in distilled water. The final growth length also measured 6-7 mm higher than the sprout soaked in distilled water, demonstrating that enough supply of oxygen to the sprout induces stability and efficiency in its growth.

• Proceedings of the Korean DIstribution Association Conference
• /
• 2006.08a
• /
• pp.47-68
• /
• 2006

This study aims to determine the association structure of the behavioral relationship variables, such as trust, commitment, cooperation, communication and coercive power, in the relationship between the buyers and suppliers of industrial parts. It also investigates the impact of the use of IT technologies on the relationships quality. Data was collected from 216 part suppliers of machinery, electronics and automobiles located in Incheon. Data supported all of the proposed hypotheses. First, it was confirmed that parts suppliers' trust in buyers leads to the commitment into relationships with buyers. Second, cooperation and communication showed a positive influence on parts suppliers' trust in buyers, and coercive power gave a negative influence on trust. Third, the use of IT technologies like Internet and E-Mail between parts suppliers and buyers was verified to have generally a positive influence on the quality of relationships. At the same time, cooperation and communication were confirmed to have a positive influence on each other, and cooperation and coercive power as well as communication and coercive power were confirmed to have negative influence on each other. This study is a pioneering attempt to examine the relationships between suppliers and buyers of industrial parts, and the influence IT technologies on the relationship quality. Also, the findings will be practically much helpful to find how to reinforce the relationships between parts suppliers and buyers.

• Korean Chemical Engineering Research
• /
• v.43 no.2
• /
• pp.243-248
• /
• 2005

Membrane pervaporation processes could have advantages over distillation for separation of water/organics mixtures: a low energy demand and the ability to separate azeotropic mixtures or isomers. Zeolite membranes might show better thermal, mechanical and chemical stabilities than polymer membranes. Water could be effectively separated from water/organic mixtures using the NaA zeolite membrane because of its high hydrophilicity. In this study, water was separated by pervaporation using the NaA zeolite membrane from water/ethanol mixtures. As a mole fraction of ethanol increased, the total permeation flux and the water flux decreased while the separation factor increased, reached a maximum point, and decreased. As an experimental temperature increased, the total permeation flux increased while the separation factor increased at the lower mole fraction of ethanol than 0.8 and it decreased at the higher mole fraction of ethanol than 0.8. The total permeation flux and the separation factor could be maintained constant during the long term experiment longer than 160 hours. It was found that the NaA zeolite membrane synthesized in our study showed better performance on water/ethanol separation than that of a distillation process or PVA polymeric pervaporation membranes.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.31 no.6
• /
• pp.1058-1064
• /
• 2002

The purpose of this study was to investigate the effects of green tea on hepatic antioxidative defense system and recovery of muscle fatigue in rat after aerobic exercise. Male Sprague-Dawley rats weighing 150$\pm$ 10 g were randomly assigned to one normal (N) group and aerobic exercise training groups. Exercise training groups were classified into two groups: training (T) group and green tea (TG) group which were supplemented the distilled water and green tea extracts by dringking water during experimental periods, respectively. The experimental rats in exercise training groups (T and TG) ran on a treadmill 30 min/day at a speed of 28 m/min (7% incline) 5 days/week or were cage confined (Normal group) for 4 weeks. And rats were sacrificed with an overdose of pentobarbital injection just after running. Hepatic xanthine oxidase (XOD) activities were not significantly different among three groups. The activity of superoxide dismutase (SOD) in T group was no significant difference from N group, but those of TG groups were significantly increased, compared with that of T group. Hepatic glutathione peroxidase (GSHpx) activites of TG groups showed a similar tendency to that of normal group, but it was increased to 20% in TG group, compared with normal group. The reduced glutathione (GSH) contents in liver was not significantly different from that of any three group. The oxidized glutathione (GSSG) contents in T group was increased to 69%, compared with the normal group, but TG group significantly decreased, compared with the T group. The ratio of GSH/GSSG in liver of T group was lower than that of normal group, but those of TG group was a similar tendency to that of normal group. Contents of thiobarbituric acid reactive substance(TBARS) in T group was increased to 52%, compared with that of normal group but those of TG group were recovered the normal level. Contents of hepatic glycogen in T group were decreased to 23% compared with those of normal group, while that of TG group was the same as normal levels. The contents of serum lactic acid in T group were increased to 261%, compared with normal group, but those of TG group maintained the normal level by green tea supplementations. In conclusion, the effects of green tea in exercise training rats would appear to reduce peroxidation of tissue as an antioxidative defense mechanism and promote recovery of muscle fatigue.

• KSBB Journal
• /
• v.15 no.2
• /
• pp.139-144
• /
• 2000

Automatic addition of glucose and ammonium to an alcohol distille깨 wastewater and the control of them at low $\infty$ncentration were tried to efficiently increase the cell concentration of a baker's yeast c비tivated in that wastewater. Added g glucose was indirectly controlled to less than 116 mg/L by a method which used DO as control parameter. Ammonium was a automatically measured and controlled within the range of 7.0~27.7 mM by a homemade on-line system which adopted FIA a as measurement method. Maximum specific growth rate and biomass yield to glucose were $0.21 hr^{-1}$ and about 0.78 g/g, w which were significantly increased values in contrast to those of an experiment without ammonium control. Biomass yield to a ammonium was 11.3 gIg. Cell cone엉ntration could be increased from 2.6 g/L to 18.5 g/L by the add ion of glucose and a ammonium.

• Korean Journal of Microbiology
• /
• v.30 no.5
• /
• pp.383-390
• /
• 1992

In the periods of July 31 to August 10. 1988 and March 9 to 13. 1989. sediment samples were collected from the South Sea stations (010] to 092]) located in the area from $N 32^{\circ}$/30' to $34^{\circ}$/30', of latitude and from E $123^{\circ}$ 30' to $128^{\circ}$30' of longitude. These samples were analyzed for the number of total heterotrophic bacteria and extracellular digesting enzyme activities. In the 1989 spring period the number of heterotrophic bacteria in the sediment surface layer was increased more than 100 times at the maximum compared to that in the 1988 summer period. The proportion of fresh water bacteria to total heterotrophic bacteria was also higher in the spring period than the summer period. The extracellular digesting enzyme activities were higher in spring season than summer. Although the water content of sediment in the spring period was lower than that the summer period. the ash weight indicating organic material content was higher. These results means that the diameters of sediment particles were larger in spring than summer but the input of organic material into the sediment was greater. Based on these results bacterial distributions in the sediment layer of South Sea depend greatly on the season due to the effect of fresh water. During the spring season plankton could grow extensively owing to the inorganic nutrients input by the vertical mixing in the water column, then be precipitated into the sediment. Organic nutrients supplied from enzymatic degradation of polymeric particle from plankton can increase the bacterial number, too.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.12
• /
• pp.1141-1146
• /
• 2010

Isolated the heterotrophic aerobic bacteria in sandfiltered water on NA and TSBA solid medium, selected 8 dominant species and identified by Sherlock System. Each samples are irradiated 0, 5, 16, 40 and $60\;mJ/cm^2$ using on CBD (Collimated Beam Device) Medium Pressure UV lamp after these identified bacterium did liquid culture how to make $10^6{\sim}10^7\;cells/mL$ suspended in dilution water. Then cultured bacteria are estimated inactivation rate on plate media. Identified Gram positive group are Bacillus Subtilus, Bacillus megaterium, Rhodococcus erythropolis and Microbacterium laevaniformans; Gram negative group are Pseudomonas vesicularis, Pseudomonas pseudoflava, Alcaligenes paradoxus and Zooglea ramigera. These isolation of bacterium are more stronger reference strain and high resistance of MP UV irradiation, Besides Gram negative bacterium are more sensitive Gram positive bacterium on MP UV dose. Now we are estimating to $60{\sim}100\;mJ/cm^2$ MP UV dose for efficient disinfection in water treatment plant.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.250.1-250.1
• /
• 2010

최근 석유공급 불안정성과 이산화탄소 배출 규제 움직임에 대응하기 위한 수단으로 바이오연료의 공급이 전세계적으로 증가하고 있다. 이와 같은 바이오디젤의 보급 활성화는 식물성 기름의 가격 상승과 수급 불안정 문제, 그리고 식량자원과의 충돌 문제를 야기하고 있다. 국내 바이오디젤 생산 원료로 사용되는 대두, 유채, 해바라기, 팜 등은 모두 식용시장과 수급 균형을 형성하고 있어 바이오디젤의 생산이 증가하게 되면 식용 오일 시장의 수급균형이 깨져 오일곡물 가격의 변동을 초래하게 될 것이다. 과거에는 수거비용을 들여 폐기하던 폐식용유 마저 이제는 돈을 주고 구입해야하는 실정에 다다랐다. 바이오디젤 생산비의 70~80%를 차지하는 원료유의 부족 현상에 따라 바이오디젤 업계에서는 soapstock, trapped grease, 폐식용유 등의 저급유지 활용 방안을 강구하고 있으며 자트로파와 같은 비식용 작물의 해외플랜테이션도 진행하고 있다. 본 연구에서는 커피찌거기에 남아 있는 오일을 속슬렛추출장치를 이용해 추출하고 전이에스테르화 반응을 수행하여 반응 특성과 커피오일 바이오디젤의 지방산 조성을 알아보고 바이오디젤 원료유로서의 사용가능성에 대해 알아보았다. 석유에테르를 용매로 속슬렛 추출장치를 이용해 추출시 원료대비 약 17%(w/w)의 오일을 추출할 수 있었다. 추출된 오일의 산가는 18.79mgKOH/g으로 매우 높아 직접 전이에스테르화 반응이 불가능하다. 고체 산 촉매 하에서 전처리 반응을 실시하여 유리지방산을 전환 제거한 후 염기촉매를 이용해 전이에스테르화 반응을 진행한 결과 약 80%의 바이오디젤(FAME) 함량을 얻을 수 있었다. 지방산 조성 분석 결과 리놀레익산(Linoleic acid, C18:2), 올레익산(Oleic acid, C18:1), 팔미틱산(Palmitic acid, C16:0)이 대부분을 차지하며 이 중에서도 리놀레익산이 44.17%로 가장 많은 함량을 보였다. 이는 커피찌꺼기 추출 오일이 바이오디젤 원료유로 활용 가능성을 나타내는 결과로, 색소성분 등의 불순물을 효율적으로 제거하여 증류정제 전단계에서의 바이오디젤 순도와 생산 수율을 증대시키기 위한 추가 연구가 필요한 것으로 판단된다.