• Journal of Wind Energy
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• v.2 no.1
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• pp.82-89
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• 2011

his dissertation is on power control system for MW-class wind turbine. Especially, the control purpose is reduction in electrical power and rotor speed. The base control structure is power curve tracking control using variable speed variable pitch operational type. For the reduction of fluctuations, more control algorithm is needed in above rated wind conditions. Because general pitch control system is low dynamic response as compared with the wind speed change. So, this paper introduces about the pitch feed forward control to minimize fluctuations of the electrical power and rotor speed. To maintain rated electrical power, the algorithm of feed forward control adds feed forward pitch amount to the pitch command of power curve tracking control. The effectiveness of the feed forward control is verified through the simulation.

• Journal of Korean Society of Water and Wastewater
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• v.16 no.6
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• pp.717-725
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• 2002

A bench-scale submerged-type membrane filtration system (SMFS) was constructed to study a feasibility of membrane filtration for solid-liquid separation in water and wastewater treatment processes. In the case of applying the SMFS to a biological wastewater treatment process, so-called membrane bioreactor, aeration underneath membrane modules is usually employed in order to provide oxygen demand for microbial growth as well as to control membrane fouling. A study was investigated the effects of operation parameters by aeration intensity, feed concentration, foulant type and airlift pore size on critical flux. Critical flux tends to increase with aeration rate. Optimal aeration flow rate was found to be 10 L/min/module. Feed concentration and foulant type has a significant effect on membrane fouling and filtration performance. But downward position and pore size of airlift has no a significant effects on membrane fouling and filtration performance.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.9
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• pp.1319-1325
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• 2002

Two experiments were conducted to evaluate the effect of early feed restriction on growth, feed conversion ratio (FCR) and mortality in unsexed broiler chickens. In Experiment 1, 350 one-day-old broiler chickens were divided into 7 groups. Each treatment group was represented by five replicates of ten broilers each. One group was fed ad libitum as the control group and the other six groups were fed 25% ad libitum (25% multiplied by amount of feed intake of ad libitum chickens at the previous day) for 4 or 6 days, 50% ad libitum for 4 or 6 days, and 75% ad libitum for 4 or 6 days. In experiment 2, 500 broiler chickens were divided into 10 groups. Each treatment group was represented by five replicates of ten broilers each. One group was fed ad libitum as the control group. Three ages of feed restriction initial timing (2, 4 or 6 days of age) and three types of feed restriction (physical restriction, meal feeding and diet dilution) were used ($3{\times}3$) in both experiments. They were feed-restricted for 6 days. Results showed that restricted broilers exhibited compensatory growth in both experiments except for diet dilution groups. In both experiments, FCR of restricted broilers was higher, whereas feed intake of them was lower during restriction period. FCR of restricted broilers was lower upon refeeding. Mortality was inconsistently affected by early feed restriction. Leg abnormality was lower in restricted broilers in both experiments. Level of feed restriction significantly influenced body weight, FCR and feed intake of restricted broilers (p<0.05), but duration of feed restriction had no effect. Type of restriction significantly affected body weight, feed intake and FCR (p<0.05). It appeared that to achieve the best result (complete compensatory growth and better FCR), broilers should be restricted at 25% ad libitum for 6 days (Experiment 1). Meal feeding started at 2 days of age would show the best performance (Experiment 2).

• Journal of Environmental Health Sciences
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• v.30 no.1
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• pp.7-14
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• 2004

The change in filamentous bacteria appearance was observed by adjusting factors such as organic and nurient concentration of feed wastewater and the aeration rate in the reactor. In case that COD:N:P and DO were 100:10:1 and 6.1 m1/1 respectively, the mean SVI was 122 ml/g and the filaments were developed normally in flocs. For the low DO con- dition, however, the SVI averaged 186 ml/g and the appearance of outgrowing filaments were more frequent. When the high organic was supplied into the reactor, the average SVI was 274 ml/g and the distinct filamentous bulking was observed. Meanwhile when COD:N:P was maintained at 100: 1 :0.5, the SVI was as low as 87 ml/g and the appearance of filaments were minimal and the size of flocs was small comparing other experimental conditions. For normal, low aeration and high organic concentration, predominant filaments in the early stage of experiments were commonly Type 021N,S. natans which were usually found in low DO condition. However, Type 041, Type 1851, Type 0961 became predominant as experiments extended. Meanwhile, in low nutrient condition, Type 0675, Type 1851, and Type 0961 were observed. The filamentous bacteria appearance for SVI< 150(ml/g), Type 0041, Type 0961 (usually low organic in feed wastewater) were predominantly observed and SVI > 150(ml/g), S. natans and Type 021N(usually low DO in aeration basin) was predominant.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.12
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• pp.2031-2038
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• 2020

Objective: This study aimed to determine the effect of intermittent feeding and cold water on performance and carcass traits in broiler chickens between 4 to 6 wk of age exposed to daily high temperature. Methods: Broilers were assigned to four treatment groups according to a 2×2 factorial design between 22 to 42 d of age (80 broilers per treatment, 4 replications). Broilers were divided into two main groups as feeding type (ad-libitum [AL] and intermittent [IF] for 6 h daily) and sub-groups as water temperature (normal [NW], 24.9℃ and cold [CW], 16.4℃). Heat treatment was applied between 11.00 to 17.00 h daily between 22 to 42 d of age. Results: Live weight at 6th wk was not affected by feeding type and water temperature, but the live weight was significantly higher in IF chickens at the 5th wk (p<0.05). Average weekly gain of IF broiler chickens were higher compared to AL group at 4, 5, and 6 wk of age (p< 0.05). Although feeding type did not affect feed intake in 4 and 5th wk, feed intake was higher in IF chickens at 6th wk (p<0.01). In addition, feeding type and water temperature did not affect feed conversion ratio and interactions were not significant (p>0.05). Water temperature had no significant effect on heart, liver, gizzard, and abdominal fat percentages (p>0.05). Conclusion: It is concluded that IF increased the average weekly gain in chickens reared under daily heat stress for 6 h between 22 to 42 d of age. IF in hot environmental conditions slightly increased performance without adversely affecting health, welfare, and physiological traits, whereas CW implementation had no significant effect on performance. It can also be said that IF suppresses a sudden increase in body temperature depending on age and live weight.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.129-129
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• 2022

The production area of Italian ryegrass feed is gradually increasing and labor-saving technologies are being developed. If sowing and fertilization are carried out agricultural drones, working hours and labor are reduced. The purpose of this study is to suggest an appropriate seedling amount for feed production by drone spreading of Italian ryegrass in spring. In addition, we would like to review the productivity of the drone seeding machine that is being developed by Rural Development Administration(RDA) of Korea. Italian ryegrass was sown by a drone in February at the NICS located in Gyehwa-hwa, Jeollabuk-do, South Korea. In Experiment 1, 50kg/ha, 60, 70, and 80 seeding rates were sown with a horizontal spreader drone. In Experiment 2, uniform spreaders type drone and horizontal spreader type were sown with the same seeding amount and compared. The drone was sown using the AF-52 aircraft. The higher the seeding amount, the higher the emergence rate. As the seeding amount increased, the plant length increased, but the number of tillers per individual decreased. The dry matter weight of the feed was the highest at 1,326kg/10a at the seeding rate of 70kg/ha, and decreased by 20.5% at the seeding rate of 80kg/ha. The coverage ratio was the highest at 96 at the seeding rate of 70kg/ha, which was the most advantageous for spring sowing. In the comparative experiment according to the spreader type, the uniform spreader had a high emergence rate per unit area. When the uniform spreader was used, the dry matter weight of the feed was 17% higher than that of the horizontal one, and the coverage was about 5% higher.

• Animal Bioscience
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• v.35 no.7
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• pp.1039-1047
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• 2022

Objective: The purpose of this study is to determine the optimal time of transportation of floor-feed and scatter-feed broilers. Methods: Eighty healthy Arbor Acres (AA) broilers (21-day-old, 624.4 g, male, standard error = 6.65) were selected and randomly divided into two experimental groups (floor-feed and scatter-feed), then fed for three weeks. The experiment comprised a 2×4 factorial design with 2 feed patterns (floor-feed and scatter-feed) and 4 transport periods (2, 3, 4, and 5 h), and 4 replicates of 5 broilers (54-day-old, 2243 g, standard error = 46.65) was used to compare weight loss, meat quality and behavior index of different groups. Results: It appeared that drip loss, meat color and resting behavior of experimental broilers changed as length of transportation (p<0.05), however, weight loss and pH were not significantly transformed (p>0.05). Compared with floor-feed group, broilers in scatter-feed group had lower pH at 24 hours (3 h) and different behavioral indicators (p<0.05). Especially indicators after 3 h transportation, there were obvious differences between the two feeding modes in the behavior reaction of stress events before slaughter with different transport duration (p<0.05). The fluctuation of data on resting behavior with scatter-feed was significantly higher than that of floor-feed broilers. There was no interaction between transport time and different feeding methods for index tested of our experiment (p>0.05). Conclusion: Comprehensive analysis showed that the maximum transport duration of floor-feed and scatter-feed broilers should not exceed 3 h, and scatter-feed broilers were more likely prone to fear.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.4
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• pp.504-510
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• 2004

Two experiments were conducted. In expt. 1, a total of fifty-four pigs (L$\times$Y$\times$D, 56.14$\pm$1.7 kg) were used for a feeding trial to determine the effect of wet feeding of a commercial-type diet without food waste (FW). Treatments were dry (Control), wet (WF) and wet+dry feeding (WDF). For wet feeding, the diet was mixed with water at a ratio of 1:2.5 (feed:water). A wet feed was given during the whole experimental period for the WF group, but the dry feed was given during the finisher period for the WDF group. In expt. 2, a total of fifty-four pigs(L$\times$Y$\times$D, 55.7$\pm$1.8 kg) were used for a feeding trial to determine the effect of wet feeding of FW. Treatments were a commercial-type dry (Control), wet fermented food waste (WFFW) and WFFW+dry feeding (WFFW+DF). For wet feeding of fermented food waste, however, some ingredients (concentrate) were added to make nutrient contents comparable to the control diet. The FW collected was ground ($\leq$5 mm), heated with a steam jacket (140$\pm$3$^{\circ}C$) and fermented with probiotics for one day in a steel container at 30-40$^{\circ}C$. For the WFFW group, the wet feed was given during the whole experimental period, but a dry feed was given during finisher period for the WFFW+DF group. In expt. 1, during the grower period, pigs fed wet feed showed higher average daily gain (ADG) and feed conversion ratio (FCR) than those fed only dry feed (p<0.05). During the finisher period, pigs in the WDF group showed better ADG and FCR than the control group. During the entire experimental period, pigs in the WDF group grew faster (p<0.05) than those in the control group, and the same trend was found in FCR. Also, dressing percentage, backfat thickness, lean %, and pork color were not affected by the wet feeding of diets in this study. In expt. 2, during the grower period, pigs fed diets containing FW showed lower (p<0.05) ADG than those fed the control diet. But FCR was better (p<0.05) in pigs fed FW than in the control group. During the finisher period, pigs in the WFFW+DF group grew faster (p<0.05) than those in the control and WFFW groups. During the entire experimental period, pigs fed the control diet showed better ADG (p<0.05) than those fed FW, but feed intake and FCR were vice versa. Dressing percentage was lower (p<0.05) in the WFFW than in the control group, but backfat was thinner in the WFFW group than in the control group. In summary, it can be concluded that wet feeding of formula feed can improve daily gain, however, feeding fermented wet food waste may reduce daily gain of finishing pigs, even though it was fermented and the nutrient was fortified with concentrates. In addition, dry feeding of a formula feed during the finishing period can improve daily gain in pigs fed a wet feed with or without food waste during the grower period.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.5
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• pp.58-64
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• 2002

Mirror surface finish of Si-wafers has been achieved by rotary in-feed machining with cup-type wheels in ELID grinding. But the diameter of the workpiece is limited with the diameter of the grinding wheel in the in-feed machining method. In this study, some finding experiments by the rotary surface grinding machine with straight type wheels were conducted, by which the possible grinding area of the workpiece is independent of the diameter of the wheels. For the purpose of investigating the grinding characteristics of large scale diametrical silicon wafer, grinding conditions such as rotation speed of grinding wheels and revolution of workpieces are varied, and grinding machine used in this experiment is rotary type surface grinding m/c equipment with an ELID unit. The surface ground using the SD8000 wheels showed that mirror like surface roughness can be attained near 2~6 nm in Ra.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.946-949
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• 2001

Mirror surface finish of Si-wafers has been achieved by rotary in-feed machining with cup-type wheels in ELID grinding. But the diameter of the workpiece is limited with the diameter of the grinding wheel in the in-feed machining method. In this study, some grinding experiments by the rotary surface grinding machine with straight type wheels were conducted, by which the possible grinding area of the workpiece is independent of the diameter of the wheels. For the purpose of investigating the grinding characteristics of large scale diametral silicon wafer, grinding conditions such as rotation speed of grinding wheels and revolution of workpiece are varied, and grinding machine used in this experiment is rotary type surface grinding m/c equipped with an ELID unit. The surface ground using the SD8000 wheels showed that mirror like surface roughness can be attained near 2~6nm in Ra.