• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.162-167
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• 2003

Finish machining of a curved surface is often carried out by an NC system with curve interpolation in the field. This NURBS interpolation adopts a feedrate optimizing strategy based on both the geometrical information and dynamic properties. In case of a finish cut using a ball-end mill. the curve interpolator needs to take the machining process into account for more improved surface, while reducing the polishing time. In this study, the effect of low machinability at the bottom of a tool on surface roughness is also considered. A particular curve interpolation algorithm is proposed for generating feedrate commands which are able to control the roughness of a curved surface. The simulation of the machined surface by the proposed algorithm was carried out, and experimental results are presented.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.417-422
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• 2002

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. In this study, the compensation device and temperature-based algorithm have been implemented on the machining center in order to compensate thermal error of machine tools under the real-time. The thermal errors are predicted using the neural network and multi-regression modeling methods. In order to compensate thermal characteristics under several operating conditions, experiments performed with five gap sensors and manufactured compensation device on the horizontal machining center.

• Animal Bioscience
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• v.36 no.1
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• pp.119-131
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• 2023

Objective: This study was to assess the effects of different doses of an essential oil blend (EOB) on growth performance, diarrhea occurrence (DO), hematological and blood biochemical profile, intestinal morphometry, morphology and microbiology, relative weight and length of organs, digestive content pH, and liver antioxidant status in weaning piglets. Methods: A total of 135 barrows (7.09±0.29 kg body weight) were allotted randomly in a randomized complete block design based on body weight with nine replications and three animals per pen. Dietary treatments were a negative control (NC): basal diet; positive control (PC): NC plus 125 mg performance-enhancing antibiotic (enramycin 8%)/kg diet; NC plus 100 mg EOB/kg diet (EO100); NC plus 200 mg EOB/kg diet (EO200); and NC plus 400 mg EOB/kg diet (EO400). Diarrhea occurrence was monitored daily, and performance at the end of each phase. Results: Gain to feed ratio was greater (p<0.05) in starter II pigs fed EO400 and EO200 than in those fed EO100. Pigs fed EO400 had lower (p<0.05) DO than those fed NC and EO100 in the total period. Pre-starter II pigs fed NC had (p<0.05) lower serum total protein and plasma protein than pigs fed PC. Pigs fed EO100 showed smaller (p<0.05) mean corpuscular volume (MCV) than pigs fed EO400. Starter II pigs fed EO400 had (p<0.05) greater MCV and lower mean corpuscular hemoglobin and erythrocytes than those fed EO100. There was a greater concentration (p<0.05) of band cells for PC, similar to EO400 and EO200. Performance-enhancing antibiotic and EOB to diets increased (p<0.05) liver superoxide dismutase activity. Conclusion: Adding 200 and 400 mg EOB/kg diet decreased DO and was advantageous to hematological and blood biochemical profile and liver antioxidant status without being detrimental to growth performance and gastrointestinal health in nursery pigs.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.4
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• pp.497-504
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• 2022

The purpose of this study is to evaluate the antibacterial effects of two liquid fluoride materials on Streptococcus mutans (S. mutans). Riva star aqua^TM (SDI, Bayswater, Australia), which consists of silver fluoride (AgF, step 1) and potassium iodide (KI, step 2), and Fluor protector^® (FP; Ivoclar Vivadent, Liechtenstein) were used for experimental groups. Experimental groups were divided into 4 groups : AgF, KI, AgF + KI and FP. For the positive control (PC) group, ampicillin was used, and the negative control group (NC) did not receive any additional treatment. Each group was divided into 30 and 50 µL groups by volume of liquid and applied to flat-coated S. mutans. The diameter of the zone of inhibition was measured. The PC and AgF groups showed larger diameters than other materials (p < 0.05), and the AgF group showed no significant difference from the PC group in the 50 µL group (p > 0.05). The FP group showed larger diameters than the AgF + KI group in the 30 µL (p = 0.009). The KI group did not show significant difference from the NC group (p > 0.05). AgF is comparable to ampicillin in antibacterial effects on S. mutans, and better than FP.

• Animal Bioscience
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• v.35 no.10
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• pp.1585-1591
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• 2022

Objective: The present study examined the effects of exogenous emulsifiers and multi-enzyme supplementation into a low energy density diet on growth performance, visceral organ parameters, blood metabolites, ileal morphology, and nutrient digestibility in broiler chickens from hatch to 21 days. Methods: One hundred and sixty-eight one-day-old Ross 308 broiler chickens were allocated in a completely randomized design to 24 pens and each pen was assigned to one of four dietary treatments to give six replications with seven chickens in a cage. Dietary treatments were: i) positive control with standard energy level (PC); ii) negative control with 100 kcal/kg lower energy of the standard level (NC); iii) NC diet supplemented 0.05% calcium stearoyl-2 lactylate as an emulsifier (NC+E); and iv) NC diet supplemented with both 0.05% calcium stearoyl-2 lactylate and 0.05% multi-enzyme (NC+E+M). Corn and soybean meal-based control diets containing vegetable oil were formulated to meet the Ross 308 nutrition specification. Chickens were fed ad-libitum with the treatment diets and sampling was conducted on day 21. Results: Our results revealed that emulsifier and multi-enzyme supplementation into NC diets improved (p<0.05) feed efficiency of the broiler chickens compared to the broiler chickens fed NC diets from hatch to 21 days. Supplementation of emulsifier and multi-enzyme into NC diet improved (p<0.05) nutrient digestibility of the broiler chickens. However, emulsifier and multi-enzyme supplementation into diet did not influence (p>0.05) visceral organ weight, blood metabolites, and intestinal morphology in broiler chickens fed NC diets. Conclusion: Supplementation of emulsifier and multi-enzyme in the NC diet would support improving growth performance in young broiler chickens with improved feed efficiency and increased nutrient digestibility thereby curtailing the negative impact of energy reduction in the diets.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.2
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• pp.102-111
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• 2000

Methodology of volumetric error identification and compensation is presented to improve the accuracy of NC machine tools by using a reference artifact and a touch trigger probe. Homogeneous transformation matrix and kinematic chain are used for modeling the geo-metric and thermal errors of a three-axis vertical machining center. The reference artifact is designed and fabricated to identify the model parameters by machine tool metrology. Parameters in the error model are able to be identified and updated by direct measurement of the reference artifact on the machine tool under the actual conditions which include the thermal interactions of error sources. A volumetric error compensation system based on IBM/PC is linked with a FANUC CNC controller to compensate for the identified volumetric error in machining workspace.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.7
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• pp.994-998
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• 2017

Objective: An experiment was conducted to determine the effect of superdosing phytase on productive performance and egg quality in laying hens. Methods: A total of 200 42-wk-old Hy-Line Brown laying hens were allotted into 1 of 5 dietary treatments with 5 replicates consisting of 8 hens per replicate. The positive control (PC) and negative control diets (NC) were prepared based on the recommended P levels in layer diets. Supplemental phytase was added to the negative control diet at 10,000 (SD10), 20,000 (SD20), or 30,000 (SD30) fytase units (FTU)/kg. Productive performance was summarized for 6 weeks from 42 weeks to 47 weeks of age. Egg quality was assessed from 4 eggs per replicate randomly collected at the conclusion of the experiment. Results: The SD20 treatment had greater (p<0.05) hen-day egg production than PC, NC, and SD10 treatment groups. There was no difference in hen-day egg production between SD20 and SD30 treatment groups. However, SD30 treatment had greater (p<0.05) hen-day egg production than PC treatment, but showed no difference in hen-day egg production as compared to NC and SD10 treatment groups. However, egg weight, egg mass, feed intake, and feed conversion ratio were not affected by dietary treatments. Egg quality including eggshell strength, eggshell color, egg yolk color, and haugh unit was not influenced by dietary treatments. Conclusion: Superdosing level of 20,000 FTU/kg phytase in diets has a positive effect on egg production rate, but no beneficial effect on egg quality in laying hens.

• Journal of The Korean Society of Grassland and Forage Science
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• v.40 no.3
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• pp.182-189
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• 2020

This study was conducted to evaluate the effect of lactic acid bacteria (LAB) inoculation to domestically-cultivated Italian ryegrass (IRG) on silage fermentation and in vitro ruminal fermentation. There were six treatments based on the LAB inoculants: 1) no addition of LAB (negative control: NC), additions of 2) commercially-available LAB (positive control: PC), 3) Lactobacillus plantarum (LPL), 4) L. paracasei (LPA), 5) L. acidophilus (LA), and 6) L. pentosus (LPT). All treatments were inoculated at a concentration of 10⁶ CFU/g and ensiled for 3, 7, 21, and 42 days in triplicate and analyzed for nutritive values when ensiling was terminated. Day 42 silage from all treatments were also examined for in vitro ruminal fermentation. After 42 days, LAB-inoculated silages had higher (P<0.05) lactic acid concentration compared to the NC. In terms of nutritive values, the silages treated with LPA, LA, and LPT showed higher (P<0.05) crude protein and lower (P<0.05) neutral detergent fiber and acid detergent fiber content compared to the rest of the treatment. In vitro ruminal dry matter degradability was not affected by LAB addition. However, LAB-treated IRG had shown higher (P<0.05) ammonia-N compared with that of the NC. LPA had shown the highest (P<0.05) volatile fatty acid concentration among the LAB examined. In conclusion, the addition of a single strain of LAB appeared to produce a quality IRG silage compared with the NC and the PC. Among the strains examined, LPA seemed to be superior to the others.

• Journal of Animal Science and Technology
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• v.62 no.3
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• pp.313-320
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• 2020

This research was performed to investigate the hypothesis that dietary mono-component protease (PRO) might improve growth performance, nutrient digestibility, and carcass characteristics of growing-finishing pigs. A total of eighty-four pigs [Duroc × (Landrace × Yorkshire), 25.3 ± 2.16 kg initial body weight] were randomly assigned to three dietary treatments (7 replicates/treatment; 2 barrows and 2 gilts/replicate) in a randomized complete block design (block = sex). The dietary treatments were prepared as follows; (1) a positive control (PC) as a typical growing-finishing diet based on corn and soybean meal, (2) PC added with 0.015% of PRO (PCPRO), and (3) a negative control (NC) added with 0.015% of PRO (NCPRO). The NC had a lower concentration of crude protein (CP) compared with PC. The PRO was a commercial product that contained 75,000 protease units/g and derived from Nocardiopsis prasina produced in Bacillus licheniformis. Dietary treatments were offered to pigs during growing and finishing periods. Measurements were growth performance, apparent total tract digestibility (ATTD) of nutrients, and carcass characteristics. The PCPRO and/or NCPRO increased average daily gain (ADG) and gain to feed ratio (G:F) during growing (p < 0.10), finishing (p < 0.05), and growing-finishing periods (p < 0.10) compared with PC. Furthermore, pigs fed PCPRO and NCPRO had higher (p < 0.05) ATTD of CP and energy during growing and/or finishing periods than those fed PC. In conclusion, the supplementation of PRO in diets improved growth performance and protein digestibility of growing-finishing pigs.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.4
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• pp.747-754
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• 2013

This study introduces a recently designed desktop-sized NC turning system and its components. This machine is designed for the ultra-precise turning of parts with a diameter of 0.5-20 mm with minimum space usage for the machine. This study aims to achieve submicron-level accuracy of movements and good rigidity of the machine for precision machining using the desktop-sized machine. The components such as the main machine structure, air bearing servo spindle, and XZ stage with needle roller guides are designed, and the designed machine is built with a PC-based CNC controller. Its static and dynamic stiffness performances and positioning resolutions are tested. Through machining tests with single-crystal diamond tools, a form error less than $0.8{\mu}m$ and surface roughness (Ra) of $0.03{\mu}m$ for workpieces are obtained.