• Journal of the Korean Society of Industry Convergence
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• v.11 no.2
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• pp.83-91
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• 2008

GMAW(Gas Metal Arc Welding) processes are usually used in industrial side in order to get its high productivity. But those are only adopted in the semi-automated welding equipment because of a lot of welding spatters. Many industrial robot actually percents from being engaged in the welding processes. The welding spatter problem of causes blocking them being a fully automated welding process.This study was carried out to investigate the optimal conditions for minimizing welding spatter generation at GMAW robot. The spatter can be significantly reduced below 2% of welding spatter generation at the following conditions ; First, below 18V at the wire-feed rate 2.0mm/min Second, below 23V at the wire-feed rate 3.6mm/min Third, below 24V at the wire-feed rate 5.5mm/min.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.24-29
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• 2017

This paper provides an experimental analysis on the breakage of the coated tool using the face-milling cutter of the machining center due to changes in the cutting speed and the feed rate. The experimental studies were conducted using STS 304 materials and the damage to the tool was analyzed according to the change in machining time. The experiments confirmed that the cutting speed and feed rate affected the tool damage and the mechanical impact and thermal shock were determined to severely damage the tool. From the production engineering point of view, it has been experimentally investigated that the increased feed rate significantly influences the material removal rate more than the increased cutting speed.

• Journal of the Korean Society of Safety
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• v.9 no.4
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• pp.17-28
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• 1994

Chip breaking is important in lathe work for maintaining good surface of the products and safety of operator. The purpose of this study is to investigate the performance of chip breaking and chip shape resulted from the carbide inserts with grooved type and obstruction type chip breaker. Experiments have been performed under the following cutting conditions, (1) constant cutting speed with variable depth of cut and feed rate, (2) constant depth of cut with variable cutting speed and feed rate. Also, the flying distance of chip and it's distribution have been investigated. As a results, good performance of chip breaking can be obtained for small radius of curvature and land width of grooved type chip breaker. And the thickness of chip increase with the increase of feed rate and decrease of cutting speed, and the chip breaking becomes easier with the increase of chip thickness due to the large deformation rate. Obstraction type chip breaker shows better performance of surface roughness than the grooved type. The flying distance of the chips over 90% are less than 1 meter, and the distance decreases as the feed rate decreases.

• Journal of Aquaculture
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• v.18 no.2
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• pp.130-132
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• 2005

Genomics research has two ultimate applied goals: to Isolate and clone genes of economic importance for bio-technology and gene-assisted selection (GAS), and to locate and use markers for marker-assisted selection (MAS) in selective breeding programs. To this end, we have identified linked markers for feed conversion efficiency growth rate, and disease resistance to enteric septicemia of catfish (ESC). Three microsatellite markers Ip266, Ip384, and Ip607 were identified to be linked to feed conversion efficiency. Similarly one marker each was identified to be linked to growth rate (Ip607) and disease resistance to ESC (Ip477). Ip607 marker linked to both growth rate and feed conversion efficiency, indicating that the QTL for both growth rate and feed conversion efficiency may either be the same or located in the same chromosomal region in the catfish genome. On phenotypic evaluation, certain traits such as growth rate can be accurately evaluated by body weight evaluation while other traits such as disease resistance can be quite complex. The linked DNA markers will be highly useful for MAS programs and for directing further efforts of genomic mapping for important quantitative traits.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.6
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• pp.899-904
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• 2018

Objective: This experiment studied the effects of first feed intake time post-hatch on growth performance, nutrient apparent metabolic rate and intestinal digestive enzyme activities in broilers. Methods: Two thousand five hundred and twenty LingNan Yellow broilers were randomly allotted to seven treatments with six replicates of 60 each. The only experimental factor was the first feed intake time which was 18, 24, 30, 36, 42, 48, and 54 hours after hatching. The whole experiment lasted for 21 days. Results: During the whole period, the 30 h treatment had the best body weight and average daily gain (p<0.05), followed by the 24 h group performance optimization. Also, the 30 h group was observed to have the best apparent metabolic rate for ether extract (p<0.05) and crude protein (p<0.05) and the highest activities of amylase, lipase and trypsin in small intestine. And the 24 h group was second only to the 30 h group in terms of the above two measures. Conclusion: These results indicated that the appropriate first feeding time of LingNan Yellow broilers was 24 to 30 hours after hatching.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.111-117
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• 2016

The cutting performance of a developed small-angle spindle tool was investigated with Al6061 using a TiAlN coated high-speed steel end mill. Up-cut and down-cut processes in a milling machine were carried out at the range of 1000-4000 rpm for spindle speed and 50-300 mm/min for feed rate. As a result, the highest cutting force in the Fx direction was obtained from the up-cut process when the spindle speed was 1000 rpm and the feed rate was 100 mm/min. In the Fy direction, the highest cutting force appeared in the up-cut process at a feed rate of 250 mm/min at the same spindle speed. Conversely, the lowest cutting force came out in the up-cut process at a spindle speed of 4000 rpm and a feed rate of 50 mm/min. As for surface finish, the finest surface roughness was obtained as Ra 0.7642 um at a spindle speed of 4000 rpm and a feed rate of 50 mm/min. Consequently, given the cutting performance of the developed small-angle spindle tool, we conclude that its use in industrial practice is feasible.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.654-658
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• 1999

To investigate an efficient microalgal feed for lariat culture of the Pacific oyster Crassostrea gigas, we prepared three types of Isochrysis aff, galbana (T-iso) : 1) freshly Harvested feed, 2) concentrated feed and 3) freeze-dried feed. The chemical compositions and fatty acid content of these feeds were evaluated and survival rate and lipid content of oyster larvae fed by these feeds were also determined. There was no significant difference in all types of feed in the gross biochemical compositions, In the fatty acid composition, the freeze-dried feed showed a significant increase in the level of polyunsaturated fatty acid (PUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) than freshly Harvested feed, especially EPA was 7.35-fold higher than freshly Harvested feed. The survival rate of the oyster larvae was the highest when the larvae were fed with a diet of $10\%$ freeze-dried and $90\%$ concentrated feed; it was 2.1-fold higher than that fed with freshly Harvested food alone. Thereafter, the survival rate decreased with the increased substitutions of freeze-dried food, finally equalling that fed $100\%$ freshly harvested feed at the $30\%$ substitution. Larval lipid content of the oyster was also the highest when the larvae were fed with a diet of $10\%$ freeze-dried and $90\%$ concentrated feed. This increase was by 1.6-fold ver that fed $100\%$ freshly Harvested cells. Thus feed produced during slack times, on a seedling aquaculture farm, and preparedas a freeze-dried diet can be used, mixed with concentrated feed, to supply diets more efficiently and to improve the larvae survival rate of Pacific oyster.

• Korean Journal of Veterinary Research
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• v.51 no.1
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• pp.1-6
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• 2011

Sixteen steers were used to investigate the efficacy of the sustained-release implant of bovine somatotropin (bST) in improving growth and feed:gain ratio during 12 weeks. Administration of the 400 mg bST implant resulted in a 16.1% increase in growth rate, and this increase was significant (p<.05). The use of the sustained-release implant did not alter (p>.05) feed intake and feed:gain ratio. Thirty-four cows were used to investigate the efficacy of the sustained-release implant of bST in milk production during 4 weeks. Administration of the 200 mg bST implant resulted in an 8.7% increase in milk production, and this increase was significant (p<.05). Twenty-four barrows were used to investigate the efficacy of the sustained-release implant of porcine somatotropin (pST) in improving growth, feed:gain ratio and backfat thickness during 6 weeks. Administration of the 120 mg pST implant resulted in a 11.4% increase in feed:gain ratio and a 60% decrease in backfat thickness, and these results were significant (p<.05). But the use of the sustained-release implant did not alter (p>.05) growth rate and feed intake.

• Korean Journal of Agricultural Science
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• v.33 no.2
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• pp.159-166
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• 2006

Threshing loss was increased due to dropping of the threshing efficiency when the 4 row head-feed combine harvested 5 row rice to improve harvesting performance of a combine. Reasonable design criteria were examined to determine the ranges of both of feed rate and the length of threshing drum for the 4 row head-feed combine being used as a 5-row combine. Harvesting performance increased as working width or working speed increased, it resulted in 15% increase when the working width increased from 4 row to 5 row. Harvesting operations of the 4 row combine performed normally in the 4 row rice in threshing loss less than 1%, however, threshing loss increased to 2.25% in the 5 row due to poor threshing efficiency. The length of threshing drum was increased from 710 mm to 810 mm as well as the speed of crop feed chain was increased from 0.61 m/s to 0.75 m/s so as to improve the poor threshing efficiency resulted from the enlarged working width from the 4 row to the 5 row, which would decrease threshing loss less than 1%.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.3
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• pp.107-117
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• 1998

In order to removal turbidity at high turbidity, this study was carried to evaluate the coagulants(Alum, PACl, PACS) that was suited the characteristics of raw water in water treatment plants and to determinate the optimum method of lime feed. When the optimum coagulant was selected the organic matter removal was also investigated as $UV_{254}$. PACl, lime first feed had the highest turbidity removal efficiency rate as above 99.1% and then $UV_{254}$ removal rate was obtained over than 88.0%. If you had the necessary of the lime feed, among the method of lime feed time interval feed largely was improved than simultaneous feed. Also, lime feed dose had about 1/5 of coagulants dose in case of Alum and PACl, but always PACS should be considerated lime dose.