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RESULTANT AND DISCRIMINANT OF ITERATE POLYNOMIALS

  • Choi, Eun-Mi
    • Honam Mathematical Journal
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    • v.32 no.3
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    • pp.493-514
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    • 2010
  • The resultant and discriminant of composite polynomials were studied by McKay and Wang using some algebraic properties. In this paper we study the resultant and discriminant of iterate polynomials. We shall use elementary computations of matrices and block matrix determinants; this could provide not only the values but also the visual structure of resultant and discriminant from elementary matrix calculation.

RESULTANT AND DISCRIMINANT OF LINEAR COMBINATION OF POLYNOMIALS

  • Choi, EunMi
    • Journal of the Chungcheong Mathematical Society
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    • v.23 no.4
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    • pp.663-677
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    • 2010
  • We investigate efficient method for the computation of resultant and discriminant of polynomials. The aim of this paper is to provide not only those values but also visual structure from elementary matrix calculation.

A Study about Character of Tool Wear and Chip on The Face Milling Cutter to Minimize Resultant Cutting Force (최소 절삭력형 밀링커터의 가공에서 공구마멸 및 칩의 특성에 관한 연구)

  • 김희술
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.9 no.2
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    • pp.72-79
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    • 2000
  • A new optimal tool design model which can be minimized the resultant cutting forces under the constrains of variables was developed. The resultant cutting forces are used as the objective function and tool angles are used as the variables. Cutting experiments of tool wear and chip length using the new and conventional tools wee carried out. Tool life of optimized cutter are more increased than those of conventional cutter by 2.29 times and 2.52 times at light and at heavy cutting conditions respectively. Chip length of optimized cutter are more increased than those of conventional cutter It is considered that the decrease of the resultant cutting forces is the cause that an effective rake and shear angles by the shape of optimal cutter.

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An Analysis of the Frequency-Dependent Resultant Ground Impedance of Vertical Ground Electrodes Installed in Parallel (병렬로 시공된 수직 접지전극의 합성접지임피던스의 주파수의존성 분석)

  • Lee, Bok-Hee;Cho, Sung-Chul;Seong, Chang-Hoon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.26 no.2
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    • pp.99-105
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    • 2012
  • This paper deals with the experimental results of the frequency-dependent resultant ground impedance of vertical ground electrodes installed with a regular n-polygon. In order to propose an effective method of installing the vertically-driven multiple ground electrodes used to obtain the low ground impedance, the resultant ground impedance of ground electrodes installed with a regular n-polygon were measured as functions of the number of ground electrodes and the frequency of test currents and the results were discussed based on the potential interferences among ground electrodes. As a consequence, the effect of potential interference on the resultant ground impedance of vertical ground electrodes is frequency-dependent and it is significant in the low frequency of a few hundreds [Hz]. The resultant ground impedance of multiple vertical ground electrodes is not decreased in linearly proportion to the number of ground electrodes due to the overlapped potential interferences. Also the distributed-parameter circuit model considering the potential interference, the frequency-dependent relative permittivity and resistivity of soil was proposed. The simulated results of the frequency-dependent resultant ground impedance of multiple vertical ground electrodes are in good agreement with the measured data.

An Analysis on Resultant Ground Impedance Based on the Potential Interference Of Parallel Ground Rods (전위간섭을 기초로 한 병렬 접지봉의 합성접지임피던스의 분석)

  • Lee, Bok-Hee;Seong, Chang-Hoon;Yang, Soon-Man
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.12
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    • pp.107-112
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    • 2011
  • Multiple ground rods are commonly used to obtain the low ground impedance, but they will not reduce the ground impedance unless the spacings between the ground rods are sufficient. This paper presents the experimental results of frequency-dependent resultant ground impedance of two ground rods in parallel. The resultant ground impedance of two ground rods in parallel were measured as functions of the spacing and length of ground rods and the frequency of test currents and were discussed based on the potential interferences. As a consequence, the frequency-dependent ground impedance of single ground rod and two combined ground rods give capacitive. It was found that the effect of potential interference on the ground impedance is directly associated with the frequency-dependent ground impedance and is strong in low frequency. Also, in order to reduce the increasing rate of resultant ground impedance of two ground rods due to potential interference to within 10(%), two ground rods in parallel will be placed over one rod length apart.

Study on the Resultant Vorticity Numerical Model of the Propeller Wake (프로펠러 후류의 총와도 수식모델 연구)

  • Park, Hui-Seung;Yoon, Hyun-Sik;Kim, Moon-Chan;Chun, Ho-Hwan
    • Journal of the Society of Naval Architects of Korea
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    • v.48 no.2
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    • pp.141-146
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    • 2011
  • This study numerically carried out the propeller open water test(POW) by solving Navier-Stokes equations governing the three-dimensional unsteady incompressible viscous flow with the turbulence closure model of the ${\kappa}-{\omega}$ SST model. Numerical simulations are performed at various range of advance ratios. Corresponding to Reynolds numbers of $5.89{\times}105{\sim}6.47{\times}105$ based on free stream velocity and the chord length at 0.7 propeller radius. The present results give a good agreement with those of the experiment. The propeller induced vortical structures have been analyzed by visualizing the resultant vorticity. As the advance ratio increases, the magnitude and length of the resultant vorticity decrease significantly. As the main focus of present study, the numerical model to present the ($r-{\theta}$) plane-averaged resultant vorticity along the streamwise direction for various advance ratios has been suggested.

Incorporating uplift in the analysis of shallowly embedded pipelines

  • Tian, Yinghui;Cassidy, Mark J.
    • Structural Engineering and Mechanics
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    • v.40 no.1
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    • pp.29-48
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    • 2011
  • Under large storm loads sections of a long pipeline on the seabed can be uplifted. Numerically this loss of contact is extremely difficult to simulate, but accounting for uplift and any subsequent recontact behaviour is a critical component in pipeline on-bottom stability analysis. A simple method numerically accounting for this uplift and reattachment, while utilising efficient force-resultant models, is provided in this paper. While force-resultant models use a plasticity framework to directly relate the resultant forces on a segment of pipe to the corresponding displacement, their historical development has concentrated on precisely modelling increasing capacity with penetration. In this paper, the emphasis is placed on the description of loss of penetration during uplifting, modelled by 'strain-softening' of the force-resultant yield surface. The proposed method employs uplift and reattachment criteria to determine the pipe uplift and recontact. The pipe node is allowed to become free, and therefore, the resistance to the applied hydrodynamic loads to be redistributed along the pipeline. Without these criteria, a localised failure will be produced and the numerical program will terminate due to singular stiffness matrix. The proposed approach is verified with geotechnical centrifuge results. To further demonstrate the practicability of the proposed method, a computational example of a 1245 m long pipeline subjected to a large storm in conditions typical of offshore North-West Australia is discussed.

A Study on Optimal Design of Face Milling Cutter Geometry(I) -With Respect to Cutting Force- (정면밀링커터의 최적설계에 대한 연구(1) -절삭력 중심으로-)

  • 김정현;김희술
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.9
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    • pp.2211-2224
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    • 1994
  • On face milling operation a new optimal cutter, which can minimize the resultant cutting forces, was designed from the cutting force model. Cutting experiments were carried out and the cutting forces of the new and conventional cutters were analyed in time and frequency domains. The resultant cutting forces were used as the objective function and cutter angles as the variables. A new optimal cutter design model which can minimize the resultant cutting forces under the constraints of variables was developed and its usefulness was proven. The cutting forces in feed direction of the newly designed cutter are reduced in comparison with those from the conventional cutter. The magnitudes of an insert frequency component of cutting force from the newly designed cutter are reduced than those from conventional cutter and the fluctuations of cutting force are also reduced.

ON IRREDUCIBILITY OF COMPOSITION POLYNOMIALS

  • Choi, EunMi
    • Journal of the Chungcheong Mathematical Society
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    • v.24 no.4
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    • pp.713-724
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    • 2011
  • We investigate the irreducibility of iterate and composite polynomials. For this purpose discriminant and resultant are computed by means of the norm function.

A Study on Quality Improvement Method for Manufacturing Process Plan (제조공정계획의 품질개선기법에 관한 연구)

  • Kim, In-Ho
    • Korean Journal of Computational Design and Engineering
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    • v.13 no.3
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    • pp.235-242
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    • 2008
  • This paper proposes a method for improving the process plan quality by use of dimensional tolerances. Dimensioning and tolerancing plays a key role in manufacturing process plan because the final part must ensure conformance with the dimensions and tolerances in its drawing. As a first step for the improvement of process plan quality, two resultant tolerances in design and process plan should be compared each other, and so a tolerance chart is used for acquisition and comparison of the two tolerances. In addition to two kinds of design and manufacturing tolerances, operational sequences or paths for the resultant dimension and tolerance are additionally recognized for measuring the quality of process plan quantitatively. Rooted tree is applied to find the related paths for the manufacturing resultant tolerances. A quality coefficient is defined by the components of two tolerances and their relations, the paths related to manufacturing resultant tolerances and the difficulty of an operation. In order to improve the quality of manufacturing process plan, the paths that two kinds of tolerances are the same or different in the rooted tree are recognized respectively and a method for tolerance rearrangement is developed. A procedure for improving the quality is suggested by combining the coefficient and the tolerance rearrangement method. A case study is applied to illustrate the efficiency of improvement method.