• Journal of The Korean Society of Grassland and Forage Science
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• v.8 no.1
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• pp.20-25
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• 1988

This experiment was conducted to find out the effects of the different cutting height on the chemical composition, energy production and relation of yields of Italian ryegrass, tall fescue and perennial ryegrass swards. It was carried out on the experimental field of Livestock Experiment Station, in Suweon, from Sept. 1986 to May 1987. The results obtained are summarized as follows: 1. Chemical composition and Van Soest fiber contents were slightly different among grasses. But were not same trend with cutting heights. At the late vegetative stage, crude protein and crude fiber content were much more in tall fescue, Ash in perennial ryegrass, E.E. and NFE in Italian ryegrass respectively. NDF, ADF, Hemicellulose, Lignin, Cellulose and Silica contents were much more in tall fescue than the others. 2. DM, DCP, TDN, StE, ME and NEL productions were appeared to high in line with Italian ryegrass, perennial ryegrass and tall fescue. In addition 6 cm cutting height was the most production in Italian ryegrass, 15 cm cutting height was the most production in perennial ryegrass and tall fescue. 3. The much more content of crude protein, the less nonstructural carbohydrate content. The less content of NDF, the much more nonstructural carbohydrate content. Green and dry matter yield before wintering were not influence the green and dry matter yield of the late vegetative stage, but green yield before wintering influenced total green yield.

• Journal of Power System Engineering
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• v.19 no.1
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• pp.64-69
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• 2015

Aluminum alloy is a material with a high strength-weight ratio and excellent thermal conductivity. It neither readily corrodes nor quickly weakens at low temperatures, but can be easily recycled. Because of these features, aluminum heat exchangers are widely used in aluminum alloy. In addition, the aluminum alloy used in other areas is expected to gradually increase. As a result, researchers have been continuously studying the cutting patterns of aluminium alloy. However, such studies are fewer than those on the cutting patterns of ordinary steel. Moreover, the research on ball endmilling with aluminium alloys has not received much attention. Therefore, in this study, an attempt was made to find the optimal cutting pattern among the seven cutting patterns for the machining of the commonly used aluminum alloy using ball endmilling for a heat exchanger. The optimal pattern was found by comparing the different shapes and surface roughness values produced by the seven patterns.

• International Journal of Precision Engineering and Manufacturing-Green Technology
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• v.5 no.5
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• pp.593-604
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• 2018

Laser-assisted machining (LAM) is known to be an effective and economical technique for improving the machinability of difficult-to-machine materials. In the LAM method, material is preheated using a laser heat source and then the preheated area is removed by following cutting tool. For laser-assisted turning (LAT), the configuration of the system is not complicated because laser irradiates from a fixed position. In contrast, laser-assisted milling (LAMill) system is not only complicated but also difficult to control because laser heat source must always move ahead of the cutting tool along a three dimensional (3D) tool path. LAMill is still early stage and cannot yet be used to machine finished products with 3D shapes. In this study, a laser-assisted fillet milling process was developed for machining 3D shapes. There are no prior studies combining fillet milling and LAMill. Laser-assisted fillet milling strategy was proposed, and effective depth of cut (EDOC) was obtained using thermal analysis. Experiments were designed using response surface method and cutting force prediction equations were developed using statistical analysis and regression analysis. The optimum machining conditions were also proposed, and energy efficiency of the LAMill was analyzed by comparing the specific cutting energy of conventional machining (CM) and LAMill.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.80-85
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• 2012

The ultrasonic cutting method is which cutting by applying high frequency vibrational energy into specific area at constant pressure. Ultrasonic cutting is consisted of power supply, transducer, booster and cutting tool. Precise designing is required since each part's shape, length and mass can affect driving frequency and vibration mode. This paper focused to cutting tool design, its length L was set by calculating vibration equation. And the value of the shape parameter a was diversified as the integral multiple and the result of 40,189Hz the analysis of Modal was shown in the length 30mm of the result of performance b in the 11th mode Also by performing harmonic response analysis, the frequency response result was 40,189Hz, which was similar to modal analysis result.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.77-82
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• 2003

In end milling process, undeformed chip thickness and cutting force vary periodically with phase change of the tool. Recently, a model has been proposed to simulate the shear and friction characteristics of an up-end milling process in terms of the equivalent oblique cutting to this. In the current study, the varying undeformed chip thickness and the cutting forces in a down-end milling process have been replaced with the equivalent ones of oblique cutting. And, the down-end milling characteristics of SM45C has been compared with that of the up-end milling previously presented with different helix angles.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.4
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• pp.85-96
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• 1988

The optimum cutting condition for rake angle in turning was investigated in (6-4) Brass and Al alloy. Results of experiments in (6-4) Brass and Al alloy are as follow. Specific cutting resistance becames higher as the depth of cutting, feed or cutting velocity decreases at same rake angle and resistance appear low value 20.deg., 25.deg.(6-4)brass, 0.deg. 20.deg.(Al alloy). The optimum cutting condition for(6-4) Brass is depth of cutting 0.5mm, rake angle 25.deg., cutting velocity 80m/min, feed 0.1mm/rev and for Al alloy is depth of cutting 0.1mm, rake angle 0.deg., cutting velocity 200m/min, feed 0.5mm/rev. The rake angle for good roughness is 20.deg. at (6-4) Brass, and that for Al alloy is 15.deg. The roughness is influenced by feed and it has the lowest value at 0.1mm/rev and the cutting condition is influenced by rake angle only.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.1
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• pp.74-81
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• 1987

The orthogonal cutting method of the nodular graphite cast iron in the lathe turning, whose structure were formulated under two kinds of annealing conditions, has been experimentally studied and the results investigated. The various characteristics of machinabilities of the nodular cast iron, depending upon its structure, have been obtained from the results as follows. (1) As depth of cut increases, the shearing strain decreases and tend gradually to increase with increase of ferrite matrix. (2) As depth of cut increases, the shearing stress slightly decreases for P$_{1}$, but it tends to increase for both of P$_{2}$ and P$_{3}$ under the same condition. The annealing effect in the process of light cutting was found to be greater than heavy cutting. (3) The cutting energy slightly decreases with the increassing of the depth of cut, and the effect of decreasing the cutting energy by the annealing is higer the light cutting than the heavy cutting. (4) The cutting equations as follow. P$_{1}$ : 2.phi.+1.58(.betha.-alpha.)=92 deg. P$_{2}$ : 2.phi.+1.40(.betha.-alpha.)=84 deg. P$_{3}$ : 2.phi.+1.37(.betha.-alpha.)=82 deg. (5) The machining constants for P$_{1}$, P$_{2}$ and P$_{3}$ which are the test-pieces in this study and classified according to the containing quantity of ferrite matrix given respectively in 78deg., 70 deg., and 68 deg. From these it can be known that the machining constants slightly decreases with increasing of the quantity of ferrite matrix contained in the nodular graphite cast iron.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.6
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• pp.906-915
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• 1986

This study reviewed the theory of acoustic emission applying generation of acoustic emission in metal cutting and proposed a relationship between fundamental cutting parameters and the root mean square (RMS) voltage of the acoustic emission on the basis of the mechanics of the orthogonal cutting operation. Experimental results are presented for 6063-T5 Auminum and the validity of this relationship is evaluated by a series of tests varying cutting speed, feed rate and rake angle in orthogonal cutting. The original formula derived theoretically has been modified in order to utilize independent of fundamental cutting parameters. RMS voltage of acoustic emission depends on cutting speed and strain rate, but it is not much affected by feed rate. Applying lubricant, the drop of RMS level has been observed.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2019.05a
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• pp.267-268
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• 2019

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.10a
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• pp.255-256
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• 2017