• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.2
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• pp.118-123
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• 2016

Overlap cutting is a fundamental method of applying abrasive water jet (AWJ) machining to milling to produce a wider surface because the nozzle outlet is approximately 1.0 mm wide. In this study, the effects of overlap cutting on the depth profile and surface roughness are investigated. The overlapping area depends on the amount of step over, which is controlled in the pick-feed direction. If the step over is equal to or larger than the diameter of the nozzle, no overlap cut occurs but large cusps remain between the cut paths. A step over as small as one-thirds of the nozzle diameter may lead to triple-overlap cutting resulting in an extraordinary depth. By using pocket milling experiments with a step over of 0.46 (or 0.47), it is verified that AWJ can produce a milled surface of titanium, one of the hard-to-cut materials, with $76{\mu}m$ Ra.

• Journal of Forest and Environmental Science
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• v.30 no.2
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• pp.218-225
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• 2014

Studies were carried out to standardize and develop a suitable macro-propagation technology for large scale production of superior clonal stock through stem cuttings in Commiphora wightii Arnott (Bhandari), a data deficient medicinal plant of arid region. For the purpose, three experiments were conducted. The first experiment was tried to elucidate the impact of various cutting diameters (0.50-0.75 cm, 0.75-1.00 cm, 1.00-1.50 cm, and >1.50 cm) in combination with varying growing conditions (sunlight, shade house and mist chamber) on shoot sprouting and rooting without using exogenous plant growth regulators. Cutting diameter (size 0.75-1.00 cm) in mist chamber has shown maximum sprouting (90.00%) and rooting (73.33%), primary root (6.67) and secondary root (16.67) followed by 1.00-1.51 cm in mist chamber. Minimum sprouting (40.00%), rooting (33.33%), number of shoot (1.33), primary root (1.00) and number of secondary root (1.00) was recorded in cutting diameter (size >1.50 cm) in sunlight. Second experiment was performed to find out optimum growth regulator concentration of rooting hormone (100, 200, 500 and 1000 ppm) of Indole-3-acetic acid (IAA) and Indole-3-butyric Acid (IBA) on adventitious root formation on cuttings diameter (size 0.25-0.50 cm) in comparison to control. Maximum rooting percentage (93.33%) was recorded in 200 ppm followed by 500 ppm (86.66%) of IBA as compared to control, which showed only 60 per cent sprouting. Third experiment was performed with newly formed juvenile micro-cuttings treated with varying concentrations of IAA and IBA. The juvenile cuttings (size 6-10 cm, basal dia <0.25 cm) were selected as micro-cuttings. The cuttings treated with IBA (500 ppm) showed 64.30% rooting as compared to other treatments. Results of above experiments indicate that cuttings (size 0.75-1.00 cm dia) may be developed in mist chamber for better performance. While using heavier cuttings, no growth promoting hormones is required however; growth regulator 200 ppm concentration of IBA rooting hormone was observed optimum for promoting macro-propagation in stem cuttings of lower diameter class (0.25-0.50 cm).

• Journal of the Korean Society for Precision Engineering
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• v.14 no.12
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• pp.143-152
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• 1997

The deflection of an end mill is very important in machining process and cutting simulation because it affects directly workpiece accuracy, cutting force, and chattering. In this study, the deflection of the end mill was studied both experimentally and by using finite element analysis. And the moment of inertia of cross sections of the helical end mill is calculated for the determination of the relation between geometry of radial cross section and rigidity of the tools. Using the Bernoulli-Euler beam theory and the concept of equivalent diameter, a deflection model is established, which includes most influences from tool geomety parameters. It was found that helix angle attenuates the rigidity of the end mill by the finite element analysis. As a result, the equivalent diameter is determined by tooth number, inscribed diameter ratio, cross sectional geometry and helix angle. Because the relation betweem equivalent diameter and each factor is nonlinear, neural network is used to decide the equivalent diameter. Input patterns and desired outputs for the neural network are obtained by FEM analysis in several case of end milling operations.

• Journal of the Korean Society for Precision Engineering
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• v.3 no.2
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• pp.91-101
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• 1986

This paper deals with the effect of static and dynamic cuttig force and the behaviour of drill life in drilling process. The experiments are performed with cemented carbide drills and high speed steel drills of 10mm in diameter and in an annealed SM45C. The conclusions are as follows (1) Dynamic cutting force is varied with the dept of hole. (2) Dynamic cutting forces of torque and thrust are increase with the increase in feed and cutting speed. (3) Chipping influence the dynamic cutting force of thrust than torque, and in the case of thrust, the amplitude is 3-7 times large than ordinary cutting state. (4) Prediction of drill life can be obtained from more easily the amplitude of static cutting force than that of dynamic cutting force.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.5
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• pp.27-34
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• 2021

This study analyzes machining characteristics and presents optimal cutting conditions by measuring the surface roughness, dimensional accuracy, and dimension straightness based on the feed rate after processing the inner diameter hall of SCM415 steel using an automatic CNC(Computerized Numerical Control) lathe. The testing material was cut using an 11.8 mm-diameter Chamdrill after mounting the 32 mm-diameter round bar on an automatic CNC lathe. The cut depth was set at 3 mm, and the cutting speed was fixed at 1500 rpm. The surface roughness, dimensional accuracy, and dimension straightness of 15 testings were measured by changing the feed rate to 0.05, 0.1, and 0.15 mm/rev, respectively. It was difficult to process more than 15 tests during the maching due to noise or break. Additionally, the optimum cutting of SCM415 steel showed excellent surface roughness in the 10^th and 11^th of testing at cutting speed and feed speed of 1500 rpm and 0.05 mm/rev, respectively. The dimensional accuracy was measured in three dimensions after drilling, which showed good results with an average range of 0.0138-0.0208 mm. Moreover, the lower the feed speed, the higher the accuracy. Additionally, the measurement results of the dimensional straightness showed that the straightness is the straightness was the best at the 1^th and 2^th cutting regardless of the feed speed.

• Journal of The Korean Society of Grassland and Forage Science
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• v.25 no.1
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• pp.23-32
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• 2005

This experiment was carried out to determine on the growth characteristics, yield and palatability in mono-cropping(T1; sorghum $\times$ sudagrass hybrid, T2; soybean) and inter-cropping[T3; sorghum $\times$ sudagrass hybrid(1) + soybean(2)]. The results obtained are summarizes follows; In plant length. leaf length, leaf width and stem diameter of sorghum $\times$ sudagrass hybrid(SSH). T3(1) was lower than T1 at 1st cutting time. But in 2nd and 3rd cutting time. T3(1) was higher than T1 Stem diameter of T2 was higher than soybean of T3(2). but plant length, leaf length and leaf width of T2 were higher than T3(1). The leaf ratio of SSH in T3(1) was higher than T1 in the first cutting time, but T3(1) was higher than T1 at 2nd and 3rd cutting time. The number of tiller of T1 was higher than SSH of T3(1) at 1st cutting time, but T3(1) was higher than T1 at 2nd and 3rd cutting time. Dead stubble rate of SSH in T3(1) showed a little lower value than T1. Dry matter and fresh yield of T1 was higher than T2 and T3. But protein yield of T3 was higher than T1 The palatability of 1st cutting time was 100.0. 76.8 and $18.5\%$ on T2, T3 and T1, respectively.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.1-7
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• 2011

The CFRP composite has a lot of merits such as mechanical characteristic, light and thermal resistance. For these merits, CFRP is applied to so many industrial area. In order to use the composite materials in the aircraft structures or machine elements, accurate surfaces for bearing mounting or joints must be provided, which require precise, machining. In this study, the specimens differentiating the stacking sequence of 5kinds were used. When drilling the carbon fiber reinforced plastics, it was checked on whether the stacking sequence reached any effect on the cutting force. Also relationship between the drill diameter is examined from the drilling experiment, which is the drilling of Fabric, Unidirectional specimen with ∅6mm, ∅10mm, ∅12mm cemented carbide drill. Considering cutting force and drilling diameter, the results are analyzed.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_2
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• pp.605-613
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• 2023

The multi-axis combined machining technology has enabled combined machining, which was difficult. However, the reality is that manufacturing costs are rising due to expensive equipment and there is a shortage of machine operation engineers. The purpose of this research is to present the optimum cutting conditions for the surface roughness when processing the inner diameter of SUS440C, which is an egg material, using a CNC automatic lathe. As a result of measuring the surface roughness, dry machining was the best at R_a0.481㎛ at a spindle speed of 4,000rpm, a feed rate of 0.05rev/min, and a cutting depth of 0.3mm. In wet machining, the highest value was R_a0.317 at a spindle speed of 2,000 rpm, a feed rate of 0.05 rev/min, and a cutting depth of 0.2 mm. The lower the feed rate, the better surface roughness appears. It was found that the feed rate had more influence than the number of revolutions and depth of cut.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.88-93
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• 1997

Ball-end milling process is widely used in the die and mold manufacturing because of suitable for the machining of free-form surface. Pencil cutting can eliminate overload in uncut area caused by large diameter of ball-end mill before finish cutting. As the ball-end mill for pencil cutting is long and thin, it is easily deflected by cutting force. The tool deflection when pencil cutting is one of the main reason of the machining errors on a free-from surface. The purpose of the research is to find out the characteristics of deflected cutter trajectory by eddy-current sensor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.157-160
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• 1995

Pencil cutting can eliminate overload in uncut area caused by large diameter ball-end mill before finish cutting. As ball-end mill for pencil cutting is long and type, it is easily deflected by cutting force. The tool deflection when pencil cutting with thin and long ball-end mill is one of the main reason of the machining errors on a free-form surface. The purpose of the research is to find the characteristics of deflected cutter trajectory by eddy-current sensor.