• 한국수소및신에너지학회논문집
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• 제14권2호
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• pp.155-170
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• 2003

$Cu-Ce/{\gamma}-Al_2O_3$ based catalysts were prepared and tested for selective oxidation of CO in a $H_2$-rich stream(1% CO, 1% $O_2$, 60% $H_2$, $N_2$ as balance). The effects of Cu loading and weight ratio(=Cu/(Cu+Ce)) upon both activity and selectivity were investigated upon the change in temperatures, It was also examined how the activity and selectivity of catalysts were varied with the presence of $CO_2$ and $H_2O$ in the reactant feed. Among the various Cu-Ce catalysts with different catalytic metal composition, Cu-Ce(4 : 16 wf%) /${\gamma}-Al_2O_3$ catalyst showed the highest activity(>$T_{99}$) and selectivities(50-80%) under wide range of temperatures($175-220^{\circ}C$). However, in the Cu-Ce(4 : 16 wt%)/ ${\gamma}-Al_2O_3$, the presence of $CO_2$ and $H_2O$ in the reactant feed decreased the activity and the maximum activity(>$T_{99}$) in terms of reaction temperature moved by about $25^{\circ}C$ toward higher temperature, the $T_{>99}$ window was seen between $210-230^{\circ}C$ (selectivity 50-75%). From $CO_2-/H_2O-TPD$, it can be concluded that the main cause for the decrease in catalytic activity may be attributed to the blockage of the active sites by competitive adsorption of water vapor and $CO_2$ with the reactant at low temperatures.

• 한국수산과학회지
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• 제17권3호
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• pp.197-205
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• 1984

열대산 메기 Clarias batrachus를 새로운 양식어종으로 만들기 위한 기초연구의 하나로 이 종의 성장적수온 및 월동을 위한 성장가능최저수온과 저수온에서의 사치가 시작되는 수온을 찾기 위해 1981년3월부터 1982년 3월까지 체중 $12{\sim}40g$사이의 1년생으로서 $14^{\circ}C$에서 $34^{\circ}C$사이의 수온에서 일련의 실험을 실시하여 다음의 결과를 얻었다. 이 종의 약 12g에서 28g사이의 것의 성장적정수온은 약 $25^{\circ}C$로 나타났고 이 수온에서는 이보다 높거나 낮은 수온에서보다 성장과 사료섭취량, 그리고 사료효율면에서 가장 좋은 결과가 나왔다. 성장최저한계수온은 $18^{\circ}C$로 나타났으며 62일간의 실험에서 1일성장률은 약 $0.1\%$로 낮았으나 폐사는 없었고 활동도 비교적 활발하였다. 따라서 이 종의 월동가능최저수온은 $18^{\circ}C$로 사료된다. $16^{\circ}C$또는 이보다 약간 낮은 수온에서 방치하면 약 30일내에 대부분 폐사하며 $14^{\circ}C$이하에서는 $1{\sim}7$일 내에 모두 폐사하였다. 따라서 이 종에 있어서 폐사가 시작되는 수온은 $16^{\circ}C$로 사료된다. 성장가능최저수온 근처에서 장기간사육할 경우 급작스런 수온하강, 특히 $15^{\circ}C$이하로 내려가는 경우 전체 어류에 치명적인 피해가 예상되므로 주의하지 않으면 안될 것으로 사료된다.

• Membrane and Water Treatment
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• 제8권2호
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• pp.113-123
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• 2017

This study investigated effects of physical and chemical cleaning methods on the initial flux recovery of fouled membrane in membrane distillation process. A laboratory scale direct contact membrane distillation (DCMD) experiment was performed to treat digested livestock wastewater with 3.89 mg/L suspended solids, 874.7 mg/L COD, 543.7 mg/L nitrogen, 15.6 mg/L total phosphorus, and pH of 8.6. A hydrophobic PVDF membrane with an average pore size of $0.22{\mu}m$ and a porosity of 75 % was installed inside a direct contact type membrane distillation module. The temperature difference between feed and permeate side was maintained at $40^{\circ}C$ with the feed and permeate stream velocity of 0.18 m/s. The results showed that the permeate flux decreased from $22.1L{\cdot}m^{-2}{\cdot}hr^{-1}$ to $19.0L{\cdot}m^{-2}{\cdot}hr^{-1}$ after 75 hours of distillation. The fouled membrane was cleaned first by physical flushing and consecutively by chemicals with NaOCl and citric acid. After the physical cleaning the flux was recovered to 92 % as compared with the initial clean water flux of the virgin membrane. Then 94 % of the flux was recovered after cleaning by 2,000 ppm NaOCl for 90 minutes and finally 97 % of flux recovered after 3 % citric acid for 90 minutes. SEM-EDS and FT-IR analysis results presented that the foulants on the membrane surface were removed effectively after each cleaning step. The contact angle measurement showed that the hydrophobicity of the membrane surface was also restored gradually after each cleaning step to reach nearly the same hydrophobicity level as the virgin membrane.

• 한국수산과학회지
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• 제52권2호
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• pp.149-158
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• 2019

This study investigated the effects of replacing fish meal (FM) with a mixture of four protein sources (wheat gluten, soy protein concentrate, tankage meal, and poultry byproduct meal) in an extruded pellet (EP) diet for olive flounder Paralichthys olivaceus. Five experimental diets were formulated with alternative proteins replacing 0%, 20%, 30%, 40%, and 50% of FM. Taurine and betaine were added as attractants in the diets. Triplicate groups of fish (initial body weight: $196{\pm}2g$) were fed the diets to apparent satiation. Over the course of a 6-month feeding trial, there were no significant differences between the groups in growth performance, feed utilization, survival, or villus height. The dry matter and protein digestibility of FM50 diet were significantly lower than those of the control diet at water temperatures below $18.5^{\circ}C$ in months 4 and 6. This is a highly significant first report on FM replacement in an EP diet given to olive flounder over a 6-month-long feeding period. It shows that the proper mixture of protein sources can replace up to 50% of FM in olive flounder EP diets with taurine and betaine supplementation. It also shows that 40% of FM could be safely replaced in EP diets during periods of low water temperature.

• 대한수의학회지
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• 제49권4호
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• pp.335-343
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• 2009

The pathogenicity and acute toxicity of Lactobacillus (L.) pentosus PL11 from eel (Anguilla japonica) were investigated using male and female Sprague-Dawley rats. The pathogenicity of L. pentosus PL11 was examined after treating the rats with $10^{11}$ CFU/mL, $10^9$ CFU/mL or $10^7$ CFU/mL doses of L. pentosus PL11 culture or 0.85% NaCl (Control) intragastrically. For acute toxicity studies, rats were treated with dried culture broth of L. pentosus PL11 at doses of 5,000 mg/mL, 2,500 mg/mL, 1,250 mg/mL or 625 mg/mL or Lactobacilli MRS broth (Control), and clinical signs or mortalities were monitored for two weeks. The results of the present investigation revealed no mortalities or obvious clinical signs in rats administered with the live bacterial cultures or dried culture broth at any investigated dose level. Also, no significant differences were observed in net body weight gain, gross pathological findings, feed and water consumption and body temperature among the different treatment groups and between the treated and control rats. It can be concluded from the above findings that L. pentosus PL11 is a safe probiotic strain with potential as feed additive to increase the feed efficiency or health of fish.

• 한국수산과학회지
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• 제41권5호
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• pp.343-345
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• 2008

This study determined the optimum feeding frequency for the growth of juvenile cherry salmon (Oncorhynchus masou). Triplicate groups of fish (initial mean weight 19.1 g) were fed extruded pellets at four feeding frequencies for 50 days: once every 2 days, once a day, twice a day, and three times a day. The mean water temperature during the feeding trial was $17.9{\pm}1.59^{\circ}C$. The survival of all groups was 100%. The final fork length of fish fed twice a day was significantly greater than that of the other groups (P<0.05). The weight gain of fish fed two and three times daily was significantly greater than that of fish fed once a day or every 2 days (P<0.05). The daily feed intake increased significantly with feeding frequency (P<0.05), but there was no significant difference in the weight gain of fish fed two or three times a day. The feed efficiency of fish fed once every 2 days was highest (P<0.05), and the feed efficiency of fish fed two or three times a day was significantly higher than that of fish fed once a day (P<0.05). The results of this study indicated that the optimum feeding frequency for the growth of juvenile cherry salmon is twice a day, while the feeding efficiency of fish fed once every 2 days was best.

• 한국식품과학회지
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• 제52권4호
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• pp.357-362
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• 2020

본 연구는 조직감 및 기능성 면에서 우수한 식물성 대체육의 제조를 위하여 부원료로 버섯을 첨가한 압출성형 대체육의 품질특성에 대하여 살펴보았다. 대체육의 원료는 분리대두단백 50%, 글루텐 40%, 옥수수 전분 10%를 섞은 것을 기본배합(base)으로 하였다. 버섯 첨가함량을 기본배합 대비 0, 4, 8, 12%로 한 총 네개의 시료를 수분함량 55%, 스크루 속도 150 rpm, 바렐 온도를 170℃로 하여 냉각 사출구를 통해 20℃로 사출하였다. 압출성형 후 물리적 특성으로 경도, 탄성, 응집성, 씹힘성과 절단 강도, 조직잔사지수, 보수력을 측정하였고, 화학적 특성으로 수용성 질소지수, 단백질 소화율과 DPPH 라디칼 소거활성을 측정하였다. 버섯 첨가함량이 증가함에 따라 경도, 탄성, 응집성, 씹힘성과 절단강도가 모두 증가하였으며, 조직잔사지수 역시 증가하였다. 반면에, 버섯 첨가함량이 증가할수록 보수력과 수용성 질소지수는 감소하였으며, 단백질 소화율도 다소 감소하였다. DPPH 라디칼 소거활성은 버섯 첨가함량의 증가에 따라 유의적인 증가를 나타내었다. 압출성형 대체육에 버섯의 첨가는 대체육의 조직감을 개선하고 항산화 기능성을 부여하는 유효한 공정임을 확인하였다.

• 공업화학
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• 제10권4호
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• pp.563-567
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• 1999

용질배제율이 우수한 나권형 FT-30 폴리아미드 복합막을 상용하여 cephalosporin C를 농축하기 역삼투 농축실험을 하였다. $4{\sim}20kg/cm^2$의 압력과 100~1000 mg/L의 농도, 그리고 2.8과 5.6 L/min의 유속을 갖는 실험 조건하에서 cephalosporin C 수용액의 수투과율과 용질의 배제율 및 물질전달 계수를 구하였다. Cephalosporin C를 분리하는데 있어서 압력이 증가함에 따라 투과 플럭스가 증가하는 것으로 나타났다. 이 결과는 Kedem-Katchalsky 모델에서 예측한 것과 일치하였다. 그리고 배제율은 1에 가까웠다. 또한 공급액의 농도가 증가할수록 cephalosporin C의 배제율은 낮아지는 것으로 나타났다. 배제율은 고농도보다는 저온도에서 높게 나타났으나 그 감소 정도는 작았다.

• 멤브레인
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• 제7권1호
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• pp.39-47
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• 1997

자체적으로 설계한 막분리 장치 시스템을 사용하여 먼저 순수한 물(3차 처리수)을 대상으로 polysulfone 재질의 중공사형 한외여과막에 대한 분리 성능을 조사하였다. 분획분자량(Molecular cutoff) 5,000 및 10,000 두 종류의 한외여과막에 대하여 실험한 결과, 온도가 증가함에 따라 공급량에 대한 투과량의 비인 회수율이 증가하는 경향을 보였다. 또한, 다양한 분자량의 polyethylene glycol 및 dextran 2,000 ppm 수용액으로 분획분자량을 확인한 결과, 표시된 값보다 다소 큰 값을 얻을 수 있었다. 이러한 기초 실험결과를 토대로 하여, 최종적으로 생활하수의 유입으로 수질이 악화되고 있는 춘천시 공지천의 물을 처리 대상으로 선정하여 원수의 성분을 분석하고, 한외여과 실험을 실시하였다. 그 결과, 생물학적 산소요구량(BOD) 및 총고형물(TS), 탁도가 모두 처리수에서 원수보다 탁월한 감소를 나타내었다. 따라서, 중공사형 한외여과막을 사용한 생활하수 처리에 가능성을 본 연구를 통하여 확인할 수 있었다.

• Asian-Australasian Journal of Animal Sciences
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• 제32권1호
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• pp.152-158
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• 2019

Objective: This study was conducted to evaluate the effect of water restriction (WR) on physiological and blood parameters in lactating dairy cows reared under Mediterranean climate. Methods: The trial lasted 16 days preceded by two weeks of adaptation to the experimental condition in spring 2014 on 6 dairy cows in mid-lactation. These cows were allowed water ad libitum for 4 days (W100) (hydration period), then split into 2 groups, one group has received 25% and the other 50% of water compared to their mean water consumption during the hydration period; then rehydrated for 4 days. Feed intake and physiological parameters: respiratory rate (RR), heart rate (HR), and rectal temperature (RT) were recorded twice a day. Blood was collected once a day and analyzed for serum concentration of glucose (Glc), triglycerides (TG), cholesterol (Chol), urea (Ur), creatinine (Crea), and total protein (TP) by enzymatic colorimetric method and cortisol (Cort) by radioimmunoassay. Results: Total dry matter intake (TDMI) was affected by WR. A decrease in TDMI was observed in WR groups compared to W100 group (effect, group, period, day, $group{\times}day$, $period{\times}day$: p<0.001). Also, WR resulted in a significant increase in RR, HR, RT in WR groups than in W100 group (effect, group: p<0.001). In addition, an increase in the serum concentration of Glc, TG, Chol, Ur, Crea, TP, and Cort was noted in WR groups (effect, group, period, day: p<0.001). Conclusion: This study has shown the ability of cows raised in a Mediterranean climate to cope with different levels of WR and thus reach a new equilibrium. As result, elucidates the important role of water as a limiting factor for livestock in environments with low water availability.