• Geomechanics and Engineering
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• v.11 no.6
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• pp.787-803
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• 2016

DDARF (Discontinuous Deformation Analysis for Rock Failure) is a numerical algorithm for simulating jointed rock masses' discontinuous deformation. While its reinforcement simulation is only limited to end-anchorage bolt, which is assumed to be a linear spring simply. Here, several new reinforcement modes in DDARF are proposed, including lining reinforcement, full-length anchorage bolt and equivalent reinforcement. In the numerical simulation, lining part is assigned higher mechanical strength than surrounding rock masses, it may include multiple virtual joints or not, depending on projects. There must be no embedding or stretching between lining blocks and surrounding blocks. To realize simulation of the full-length anchorage bolt, at every discontinuity passed through the bolt, a set of normal and tangential spring needs to be added along the bolt's axial and tangential direction. Thus, bolt's axial force, shearing force and full-length anchorage effect are all realized synchronously. And, failure criterions of anchorage effect are established for different failure modes. In the meantime, from the perspective of improving surrounding rock masses' overall strength, a new equivalent and tentative simulation method is proposed, it can save calculation storage and improve efficiency. Along the text, simulation algorithms and applications of these new reinforcement modes in DDARF are given.

• Journal of Computational Design and Engineering
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• v.2 no.4
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• pp.233-247
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• 2015

In this paper, the cutting force calculation of ball-end mill processing was modeled mathematically. All derivations of cutting forces were directly based on the tangential, radial, and axial cutting force components. In the developed mathematical model of cutting forces, the relationship of average cutting force and the feed per flute was characterized as a linear function. The cutting force coefficient model was formulated by a function of average cutting force and other parameters such as cutter geometry, cutting conditions, and so on. An experimental method was proposed based on the stable milling condition to estimate the cutting force coefficients for ball-end mill. This method could be applied for each pair of tool and workpiece. The developed cutting force model has been successfully verified experimentally with very promising results.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.4
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• pp.389-393
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• 2014

This paper presents one of the methods for design to reduce the noise and vibration of 200kW motor for electric propulsion ship. One of the important factors affecting vibration of the motor is the resonance. The natural frequency and natural mode of the 200kW motor is analyzed by using FEM tool and impact test equipment to avoid the resonance. Also, compare FEM result with impact test result to make a reliable FE model of 200kW motor. In order to find out the effect of the noise and vibration of the motor by electromagnetic excitation force, conduct electromagnetic-structure coupled analysis. These characteristics are much useful to design 200kW motor for electric propulsion ship.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.814-817
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• 2000

This paper has two purposes. One is to investigate the effect of the helix angle of endmilling cutter on the cutting haracteristics of inconel 718 in down endmilling. To this end a newly developed cutting force model in down end milling process is presented. Using this cutting force components of 4-tooth endmills with various helix angles have been predicted. Predicted values of cutting force components are well coincide with the measured ones. The other is to compare the down endmilling characteristics of lnconel 718 with those of the up milling previously presented. In up endmilling as the helix angle becomes larger the radial and tangential components of the specific cutting force ($K_1 and K_r$) decrease. While in down milling $K_1 and K_r$ become smaller as the helix angle decrease.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.63-68
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• 1996

In this study, the effect of tool rake angles and the change of cutting conditions on specific cutting pressure in face milling is investigated. The cutting force in face milling is predicted from the double cutting edge model in 3-dimensional cutting. Conventional specific cutting pressure model is modified by considering the variation of tool rake angles. Effectiveness of the modified cutting force model is verified by the experiments using special face milling cutters with different cutter pockets and various rake angles. From the comparison of the pressented model and the specific cutting pressure, it is shown that the axial force can be predicted by the tangential and redial forces without the knowledge of friction angle and shear angle. Also, the relation between specific cutting pressure and cutting cindition including feedrate, cutting velocity and depth of cut is studied.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.9
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• pp.112-120
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• 2009

In this paper the purpose is to investigate the stability and variation of natural frequency of a cracked Timoshenko cantilever beams subjected to subtangential follower force. In addition, an analysis of the stability of a cantilever beam as the crack effect and slenderness ratio is investigated. The governing differential equations of a Timoshenko beam subjected to an end tangential follower force are derived via Hamilton's principle. The two coupled governing differential equations are reduced to one fourth order ordinary differential equation in terms of the flexural displacement. By using the results of this paper, we can obtain the judgment base that the choice of beam models for the effect of slenderness ratio and crack.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.903-906
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• 2005

The purpose of this paper is to investigate free vibrations and critical loads of the uniform Beck's columns with a tip spring, carrying a tip mass. The ordinary differential equation governing free vibrations of such Beck's column subjected to a follower force is derived based on the Bernoulli-Euler beam theory. Both the divergence and flutter critical loads are calculated from the load-frequency curves that are obtained by solving the differential equation numerically. The critical loads are presented in the figures as functions of various non-dimensional system parameters such as the mass moment of inertia and spring parameter.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.1
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• pp.147-152
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• 1993

The lapping characteristics of single crystal diamond are studied by considering the crystallographic anisotropy. It is introduced for lapping method to identify crystallographic orientantion by the X-ray diffraction and to measure lapping force ratio, lapping temperature and lapping wear. Diamound bonded wheels are used for lapping under dry condition. On the lapping {110} and {100} planes, it shows remarkable crystallographic anistropy. The lapping force ratio, temperature and wear become gerater with sliding direction along the <100> than along <110>. The results also show that the wear of diamond is influenced by mechanical work(tangential lapping force * lapping distance) as well by lapping speed.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.724-725
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• 2015

본 논문에서는 모터의 방사계 소음 진동에 영향을 미치는 표면전자기력의 발생 매커니즘을 확인하고자 한다. 고정자 표면에서 발생하는 전자기력 가운데 토크에 기여하지 않는 성분을 구분하기 위해 전자리겨 성분을 Radial과 Tangential방향으로 나눈다. 이 중 토크에 기여하지 않는 Radial방향의 힘을 발생시키는 Tangential Flux Density성분의 분포를 확인하고, 자속 포화도 분포와 어떠한 관계가 있는지 확인한다. 모터의 자속밀도 및 전자기력에 대한 계산은 유한요소해석을 기반으로 한 수치 해석기법을 통해 수행하였다.

• Structural Engineering and Mechanics
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• v.30 no.5
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• pp.577-592
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• 2008

Laplace-Fourier transform techniques are used to investigate the interaction caused by mechanical, thermal and microstress sources in a generalized thermomicrostretch elastic medium with temperature-dependent mechanical properties. The modulus of elasticity is taken as a linear function of reference temperature. The integral transforms are inverted using a numerical technique to obtain the normal stress, tangential stress, tangential couple stress, microstress and temperature distribution. Effect of temperature dependent modulus of elasticity and thermal relaxation times have been depicted graphically on the resulting quantities. Comparisons are made with the results predicted by the theories of generalized thermoelasticity. Some particular cases are also deduced from the present investigation.