• KSBB Journal
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• v.18 no.5
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• pp.418-423
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• 2003

A laboratory jar fermenter was modified to measure the duration for cooling water supply and the temperatures of the coolant at the inlet and outlet of water jacket. Successful operation of temperature control and on-line measurement was achieved by adjusting optimum parameters of the Proportion-Integral-Derivative temperature controller. The variables measured on-line were used to estimate cooling rates from empirical equations comprised of the time period of cooling water supply and the temperatures of coolant. The measured cooling rate showed a good correlation to the specific growth rate during batch cultivation of E. coli. Cooling rate was measured and applied to programmed cell growth in a fed-batch cultivations. Three fed-batch cultivations were demonstrated by feeding substrate to follow the programmed cooling rates increasing exponentially.

• Journal of Aquaculture
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• v.18 no.1
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• pp.45-51
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• 2005

The optimum salinity and the effects of rapid salinity change on oxygen consumption and ammonia nitrogen excretion were examined in River Puffer Takifugu obscrus (total length 9.5$\pm$0.9 cm, total weight 18.7$\pm$5.4 g). Fish examined at the different transfer medium salinity (2, 12, 22 and 32 psu) after 2 months of acclimation period at each salinities. The routine metabolic rates of River puffer are shown as parabola equation, $Y=-0.0873X^2+0.6384X-0.690$ for oxygen consumption and $Y=-2.1667X^2+7.1672X+31.999$ for ammonia nitrogen excretion with the salinity medium at 2, 12. 22 and 32 psu. The oxygen consumption and ammonia nitrogen excretion of River puffer trans-ferred to the low salinity medium (2 and 12 psu) showed significantly difference in each salinities rearing groups than to salinity of 22 and 32 psu. Fish has a diurnal rhythm in relate to feeding, it was showed that the peak of oxygen consumption appeared at 3 hours after feeding and the ammonia nitrogen excretion rate reached maximum 4 hours after feeding. These results may indicate that the optimum salinity for rearing of River puffer is 22 psu based on growth and feed conversion ratio. The rapid change of medium salinity had no effects on the oxygen consumption and nitrogen excretion in River puffer based on this experiment.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.7
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• pp.477-484
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• 2016

In a multi-effect solar distiller, a feeding rate of seawater to each effect should be decreased as the effect number is increased. In previous studies, the feed rate of seawater was not reduced evenly between the effects, which is unreasonable, since the thermal energy input of each effect decreases by the same amount. In this work, numerical analysis was carried out in order to elucidate this discrepancy. The results showed that the amount of distillates produced was almost the same for both evenly and unevenly reduced flow rates between the effects. Optimum feed rates of seawater with various energy inputs from exhaust gas heat exchanger were also obtained. The results showed that the optimum feed rate of the first effect increased linearly or reached a steady state depending on the heat flux.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.5
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• pp.681-685
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• 2000

A computer software was developed in our laboratory to automatically control the pigs environment by the image analysis system (IAS), which monitors and analyzes the pig's behavior and feeds the results back to the computer hardware. Three feeding trials were conducted with growing pigs ($L{\times}Y$) to test the effectiveness of the IAS under various seasons. In all three trials, the open-sided conventional pens with half-slatted floor were used as controls; for the IAS treatment, fully-slatted floors were used in the windowless pens. Experiment 1 was conducted in the winter for 30 d with 24 growing pigs. There were two treatments (Conventional vs. IAS), and three pens (replicates) per treatment. During the growing period, the feed efficiency was significantly (p<0.05) improved by the IAS. In addition, the pigs reared under the IAS during the growing period displayed better growth rate during the finishing period than did the pigs reared under the conventional conditions. Experiment 2 was conducted in the summer for 30 d with 24 growing pigs. The experimental design was the same as Experiment 1. During the finishing period, all the pigs were kept in conventional open-sided pens until their market weights to evaluate their carcass characteristics. During the growing period, the growth rate and feed efficiency of the pigs in the IAS was better than those of the control pigs. In addition, various carcass characteristics were significantly improved by the IAS rearing during the growing period. Experiment 3 was conducted with 30 growing pigs for 30 d in the spring. The experimental design was the same as Experiment 1. No difference was found in growing performance between the control and IAS pigs. It could be concluded that the IAS is effective in providing optimum conditions for the growing pigs in summer and winter seasons. In addition, providing an optimum environment during the growing period results in improved growth rate, feed efficiency, and carcass qualities for the finishing pigs.

• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.4
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• pp.271-276
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• 2003

A Jeju local variety of Italian millet (Setaria italica Beauvois) was grown at five seeding rates (6, 9, 12, 15 and 15 kg/ha) from May 1 to August 25, 2003 at Jeju to determine influence of seeding rate on agronomic characters, forage yield and quality. Days to flowering increased from 89 to 96 days as seeding rate increased from 6 to 18 kg/ha. The plant height increased from 128 to 148cm as seeding rate was increased from 6 to 12 kg/ha and then decreased to 131cm at a rate of 18 kg/ha. With increasing seeding rate, stem diameter, number of leaves, number of nodes, leaf width and weight per plant decreased but leaf length had the same trend with plant height. As seeding rate increased from 6 to 12 kg/ha, fresh furage, dry matter, crude protein, and total digestible nutrients (TDN) yield increased from 35.93 to 54.83 MT/ha, 10.49 to 17.43 MT/ha, 0.94 to 1.79 MT/ha and 5.33 to 9.27 MT/ha, respectively, and then decreased with further increased seeding rates. Crude protein, either extract, nitrogen free extract, and TDN content increased 9.0 to 12.01％, 1.3 to 1.8%, 45.6 to 47.8% and 50.8 to 55.0%, respectively, but crude fiber content decreased 35.2 to 30.0% and crude ash declined 5.8 to 8.4% as seeding rate increased from f to 18 kg/ha. The optimum seeding rate to obtain the highest forage yield was estimated to be 12 kg/ha.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.4
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• pp.859-867
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• 2014

This study was conducted to evaluate the optimum dietary lipid level in juvenile river puffer. Five semi-purified diets were formulated with corn oil to contain graded levels of lipid levels of 6, 9, 12, 15 and 18%. Fish averaging $8.32{\pm}0.02$ g randomly were fed the experimental diets in triplicate groups for 8 weeks. After the 8-weeks feeding trial, weight gain and specific growth rate of fish fed the 9% diet were significantly higher than those of fish fed the 15 and 18% diets (P<0.05) but there was not significantly different from that of fish fed the 6, 9 and 12% diets. Feed efficiency and protein efficiency ratio of fish fed the 6, 9 and 12% diets were significantly higher than those of fish fed the 18% diet (P<0.05). Visceralsomatic index of fish fed 18% diet was significantly higher than that of fish fed the 6% diet (P <0.05) but there was not significantly different from that of fish fed the 9, 12, 15 and 18% diets. No significant differences were observed in condition factor, hepatosomatic index and whole body composition among all the fish groups. Serum cholesterol and triglyceride fish fed of 18% diet were significantly higher than that of fish fed the other diets (P<0.05). Optimum dietary lipid levels by using broken-line model and by using second order polynomial were estimated at 7.01% and 8.98% for the maximum growth of fish respectively. Therefore, these results suggested that the optimum dietary lipid level could be greater than 7.01% but less than 8.98% for the maximum growth in juvenile river puffer.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.4
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• pp.915-922
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• 2014

This study was conducted to evaluate the optimum dietary protein level in juvenile river puffer. Five semi-purified diets were formulated by using casein to contain graded levels of protein levels of 35, 45, 50, 55 and 65%. Fish averaging $8.56{\pm}0.04g$ were randomly assigned to one of five experimental diets in triplicate groups for 8 weeks. After the 8-weeks of feeding trial, weight gain and feed efficiency of fish fed 45, 50 and 55% diets were significantly higher than those of fish fed 35 and 65% diets (P<0.05). Protein efficiency ratio of fish fed the 35% diet was significantly higher than those of fish fed 65% diet (P<0.05), but there were no significant difference among those of fish fed 45, 50 and 55% diets. Specific growth rate of fish fed 50% diet was significantly higher than those of fish fed 35 and 65% diets (P<0.05), but there was no significant difference among those of fish fed 45, 50 and 55% diets. No significant differences were observed in condition factor, hepatosomatic index, visceralsomatic index and survival among those of fish fed all the diets. Optimum dietary protein levels by using broken-line model and by using second order polynomial were estimated at 45.9% and 51.6% for the maximum growth of fish respectively. Therefore, these results suggested that the optimum dietary protein level could be greater than 45.9% but less than 51.6% for the maximum growth in juvenile river puffer.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.3
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• pp.222-230
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• 1995

This study was canied out to ddermine optimum areas for various sizes of land coverage of the farm machinery utilization in 1993-1994. A kind of machinery size and work systems were classed as the power tiller of 10HP+man power, the tractor of 35~46HP (tractor of 64~86HP and attachment were leased to harvest work), 64-86HP+ attachment and 90- 105HP+ attachment, respectively. \ulcornerhe results are summarized as follows: 1. The optimum areas of tractors of 90~105HP, 64~86HP and the power tiller of lOHP were estimated as 21.9 (corn-rye cropping system)- 26.9ha (sorghum $\times$ sudangrass - rye cropping system), 14.7 - 22.8ha and 1.2 - 1.61ha, respectively. The break-even-point areas of the tractors of 90-105HP. 64-86HP and the power tiller of lOHP were 16.6 (corn-rye cropping system)- 19.9ha (sorghum $\times$ sudangrass - rye cropping system), 12.5 - 16.lha and 0.12-0.13ha, respectively. 2. The optimum areas (land sizes, annual field capacity) for 50 cows by feeding rate(%) of roughage to concentrate were 6.8ha, 13.6ha in the 4060, 8.5ha, 17.0ha in the 5050 and 10.2ha, 20.4ha in the 60:40, and in case of 30 cows, it were 4.lha, 8.2ha in the 40:60, respectively. In the former case for the form of work system was the trador of 90-105HP+attachment and 64~86HP+ attachment, and the latter was the tractor of 35~46HP (tractor of 64~86HP and attachment were leased to harvest work) and 64-86HP+ attachment. 3. Productiori cost for corn-rye cropping system reducted to 51.8% in 102.9 wonkg dry matter the tractor of 90~ 105HP+ attachment with 213.4 wonkg dry matter the power tiller of 10HP+ man power.

• Journal of Powder Materials
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• v.15 no.3
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• pp.221-226
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• 2008

Silver coated copper composite powders were prepared by electroless plating method by controlling the activation and deposition process variables such as feeding rate of silver ions solution, concentration of reductant and molar ratio of activation solution $(NH_4OH/(NH_4)_2SO_4)$ at room temperature. The characteristics of the product were verified by using a scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic absorption (A.A.). It is noted that completely cleansing the copper oxide layers and protecting the copper particles surface from hydrolysis were important to obtain high quality Ag-Cu composite powders. The optimum conditions of Ag-Cu composite powder synthesis were $NH_4OH/(NH_4)_2SO_4$ molar ratio 4, concentration of reductant 15g/l and feeding rate of silver ions solution 2 ml/min.

• Journal of Animal Environmental Science
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• v.5 no.3
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• pp.189-196
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• 1999

Anaerobic digestion is a naturally occuring microbial process involving the decomposition of organic materials such as livestock manure. This study explores the effect of the operating conditions, HRT (Hydraulic Retention Time) and feeding frequency on treatment efficiency for digestion of pig slurry, which has been one of most difficult organic waste for proper treatment in livestock production industry in Korea at the present time. The pilot-scale CSTR of 5 m3 in volume was designed. manufactured, and operated at the temperature of 35$\pm$1$^{\circ}C$. The digester was designed to hydraulically stir for complete mixing and to supply heat from the water bath to maintain mesophilic temperature. The HRT of the digester for Test 1 and Test 2, and Test 3 was set for 17 days and 13 days respectively and pig slurry was fed once a day with 300$\ell$ each for Test 1 and Test 3, while twice with 150$\ell$each for Test 2. Test 2 showed better performance by increase of 4% in VS removal efficiency and 5% in biogas production rate. This is mainly attributed to smaller temperature drop by feeding frequently with half amount, which eventually led to lesser impact on anaerobic mocrobes in the digester. Test 2 maintained optimum pH 7.8 which uplifted the activaton of sulfur-reduction bacteria, alkalinity of around 4,000mg/$\ell$, VA of over 3,000mg/$\ell$ for whole period of experiment. Further research may require to provide the practical operation strategy of anaerobic treatment system for treatment of pig slurry.