• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.78-87
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• 2001

This paper deals with the study on the cutting characteristics in ball-end milling process. First of all, the effects of the geometric cutting conditions such as the cutting speed, feedrates and the path interval on the surface integrity were evaluat-ed by the analytical and the experimental approaches. Secondly, the cutting mechanism model was developed to predict the cutting force accurately. It is possible for the proposed model to predict the shape error, estimate system stability and build the reliable adaptive control system. A large amount of experimental set are performed to show the validities of the proposed theories and to investigate the effect of cutting geometry such as rubbing effects, burr effects and etc.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.31-35
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• 1996

The cross section of the circular rod type workpiece to be cut in the band saw machine is variable at every moment in the sawing process. When the cutting feed rate is fixed to the constant speed, the cutting edges of the band saw teeth are also variabl eat any moment, so this causes the wear of the land saw teeth and the deterioration of the quality in the surface roughness. In this study, to work out this kind of problem basically, the mean cutting force of a tooth in the band saw was estimated by using the workpiece which was smaller than the interval of each tooth, i.e. band saw pitch, in the thickness. Then the static cutting forces were predicted by appling the mean cutting forces referred above to the mechanistic cutting force model which were analyzed through the geometric profile of a band saw tooth.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.11
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• pp.45-51
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• 1995

In order to suggest the proper cutting conditons of the CNC milling machining for the free-form surface, some experments were carried out. In the experiments, the influence of cutting conditions on a inclined spherical surface were examined by geometrical analysis. In this study, the roundness and cutting force were measured to know the effect of several cutting conditions on the machined surface and the cutting characteristics were carefully investigated. The results obtained in this study are aw follows. 1) If the tool ha s enough rigidity, we can get better dimensional accuracy in up-ward cutting than down- ward cutting. 2) A great roundness error is appeared on the surface declined under 30 degress to the horizontal plane in circular machining by a bal end mill. 3) If the thrust force is increased, the stability of tool is decreased. And the phenomenon is apperared in great in down-ward cutting than up-ward cutting.

• Journal of Ecology and Environment
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• v.35 no.3
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• pp.235-242
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• 2012

Mikania micrantha, a neo-tropical vine, is spreading rapidly in the tropical part of Nepal and is now threatening the rural ecosystem including biodiversity and rural livelihoods. However, no attempt has been made to control the spread of M. micrantha. As a result, the vines are spreading freely and rapidly. After a thorough literature review and assessment of forest management practices, we proposed a manual cutting method, as it suits the Nepalese situation for several reasons: required labor is readily available, as local communities are managing forest patches, and the method does not have any potential adverse effects on non-target native species. Experimental plots were laid out in August 2011 to examine the effectiveness of manual cutting. Two different site types based on canopy coverage were selected and divided into three blocks based on cutting strategy. Four treatments were assigned across the experimental plots following a complete block design. We harvested above-ground biomass according to the assigned treatment. The results suggested that there should be at least two consecutive cuttings within a 3-week interval before flowering, and that three consecutive cuttings resulted in 91% mortality of the vines. In addition, cutting promoted regeneration of native plant species. Employing regular cutting operations can modify understory shade enhancing regeneration of native species, which is a desirable condition to constrain proliferation of M. micrantha. Periodic cuttings reduced the competitiveness of M. micrantha regardless of canopy openness, but native ground cover should be retained.

• International Journal of CAD/CAM
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• v.7 no.1
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• pp.21-30
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• 2007

The inverse offset method (IOM) is widely used for generating cutter paths from the point-based surface where the surface is characterised by a set of surface points rather than parametric polynomial surface equations. In the IOM, cutter path planning is carried out by specifying the grid sizes, called the step-forward and step-interval distances respectively in the forward and transverse cutting directions. The step-forward distance causes the chordal deviation and the step-forward distance produces the cusp. The chordal deviation and cusp are also functions of local surface slopes and curvatures. As the slopes and curvatures vary over the surface, different step-forward and step-interval distances are appropriate in different areas for obtaining the machined surface accurately and efficiently. In this paper, the chordal deviation and cusp height are calculated in consideration with the surface slopes and curvatures, and their combined effect is used to estimate the machined surface error. An adaptive grid generation algorithm is proposed, which enables the IOM to generate cutter paths adaptively using different step-forward and step-interval distances in different regions rather than constant step-forward and step-interval distances for entire surface.

• Korean Journal of Mathematics
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• v.4 no.1
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• pp.17-30
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• 1996

In ergodic theory cutting and stacking constructions have been used to obtain a variety of important examples of transformations on the unit interval. We examine the example constructed by J. von Neumann and Kakutani and then apply the method used in the construction of Chacon's transformation to make examples that are weakly mixing but not mixing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.627-628
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• 2007

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.4
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• pp.87-92
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• 2013

In this study, we carried out the turning of plastic mold steel(STAVAX) with whisker reinforced ceramic tool(WA1) and analyzed ANOVA(Analysis of Variance) test. Multi-regression analysis was performed to find influential factors to surface roughness and to derive regression equation. Results are follows: From ANOVA test and confidence interval analysis of surface roughness, We found that influential factors to surface roughness was feed rate, cutting speed and depth of cut in order. From multi-regression analysis, we derived regression equation of STAVAX. it's coefficient of determination($R^2$) was 0.945 and It means that regression equation is significant. From experimental verification, we confirmed that surface roughness was predictable by regression equation. Compared with former research, we confirmed that increase of feed rate is the main cause of the growing of surface roughness and cutting force.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.4
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• pp.238-244
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• 1995

The objective of this study is to obtain the basic data for investigating the effects of organic reserves on winter survial or regrowth yield. Forage rape(Brassica napus L.) was sown on Sep. 1, 1994. Experimental plots were divided into three replicates under 6 different cutting dates(l0 days interval from Oct. 15 to Dec. 4). Field-grown palnts were sampled on the each cutting date and on the wintering period (Jan. 16) to analyze the nitrogen and non-structural cahohydrate reserves. The rate of winter survival and regrowth yield were also measured in the spring of next year. On the before wintering, dry matter yields were 152, 274, 500, 718, 776 and 981 kg/lOa, respectively, from the cutting date on Oct. 15, Oct. 25, Nov. 4, Nov. 14, Nov. 24, and Dec. 4. Cmde protein yield significantly increased as cutting date was later until Nov. 14, thereafter a significant increase did not occured. Nitrogen and starch contents per plant significnatly increased as the cutting date was later. The increasing rate of starch was greatly higher than that of nitrogen. On the wintering period, nitrogen reserves in mts were 85.3, 68.8, 47.6, 28.3, 44.3, and 55.3 mglplant, and starch reserve were 11 1.3, 75.3, 39.3, 19.6, 26.4 and 34.6 mglplant, respectively, in the plots cut on Oct. 15, Oct. 25, Nov. 4, Nov. 14, Nov. 24, and Dec. 4. It showed that carbohydrate reserves were much highly utilized than nitrogen reserves during wintering period. The rates of winter survival were 91, 83, 46, 22, 35 and 43% and regrowth yields were 692, 545, 316, 84, 127 and 140 kgD.M/lOa, respectively, in each plots. The highly significant correlation (p<0.01) between the level of organic reserves and the rate of winter survival or regrowth yield were obtained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1749-1752
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• 2005

High speed machining has become the main issue of metal cutting. Due to increase of the rotational speed of the spindle, problems, such as the run-out errors, reduced stiffness, must be overcome to improve the machining accuracy. In order to solve the problems, it is important to determine the appropriate clamping unit and tooling system. This paper presents an investigation into an evaluation of contact interval which is the interface between spindle taper hole and tool holder shank of the spindle. Finite element analysis is performed by using a commercial code ANSYS according to variation of clamping forces and rotational speeds. This paper proposed fit tolerance in order to evaluate the effects of clamping force and rotational speed on the contact interval in the spindle interface. From the finite element results, it has been shown that the rotational speed rather than clamping force mostly influence on the variation of the contact interval.