• Advances in Computational Design
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• 제5권1호
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• pp.13-34
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• 2020

As small size and complex metal machining components demand increases, cutting processes in microscale become necessary. Ball-end milling is a commonly used finishing process, which nowadays can be applied in the microscale size. Surface quality and dimensional accuracy are two basic parameters that affect small size components in their assembly and functionality. Thus, good quality can be achieved by optimizing the cutting conditions of the procedure. This study presents a 3D simulation model of ball-end milling in microscale developed in a commercial CAD software and its optical and computing results. These carried out results are resumed to surface topomorphy, surface roughness, chip geometry and cutting forces calculations that arising during the cutting process. A great number of simulations were performed in a milling machine centre, applying the discretized kinematics of the procedure and the final results were compared with measurements of Al7075-T651 experiments.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.1062-1065
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• 2002

We have evaluated the ability of a time-delayed artificial neural network (TDANN) to predict muscle forces using only eletromyographic(EMG) signals. To achieve this goal, tendon forces and EMG signals were measured simultaneously in the gastrocnemius muscle of a dog while walking on a motor-driven treadmill. Direct measurements of tendon forces were performed using an implantable force transducer and EMG signals were recorded using surface electrodes. Under dynamic conditions, the relationship between muscle force and EMG signal is nonlinear and time-dependent. Thus, we adopted EMG amplitude estimation with adaptive smoothing window length. This approach improved the prediction ability of muscle force in the TDANN training. The experimental results indicated that dynamic tendon forces from EMG signals could be predicted using the TDANN, in vivo.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.125-130
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• 1988

This study presents a method to determine the ground reation forces of a quadruped walking machine on its foot ends caused by the body weight and the inertia forces from the commanded acceleration. The method shows the same result as the Pseudo-Inverse Method when the 4 feet stand on a plane. However method can be applied even when the 4 feet stand on a non-planar surface for which, no feasible solution can be obtained by the Pesudo-Inverse Method.

• 대한조선학회논문집
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• 제40권5호
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• pp.26-35
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• 2003

Propellers operating in a given nonuniform ship wake generate unsteady loads leading to undesirable stern vibration problems. The skew is known to be the most proper and effective geometric parameter to control or reduce the fluctuating forces on the shaft. This paper assumes the skew profile as either a quadratic or a cubic function of the radius and determines the coefficients of the polynomial function by applying the simplex method. The method uses the converted unconstrained algorithm to solve the constrained minimization problem of 6-component shaft excitation forces. The propeller excitation was computed either by applying the two-dimensional gust theory for quick estimation or by the fully three-dimensional unsteady lifting surface theory in time domain for an accurate solution. A sample result demonstrates that the shaft forces can be further reduced through optimization from the original design.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1210-1211
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• 2011

The inherent drawback of iron-core type permanent magnet linear synchronous motor (PMLSM) is detent force that is dependent on several major factors such as PM length, slot clearance, and skewing. To minimize the detent force, this paper proposes a structure optimization using the combination computation of two dimensional (2-D) finite element analysis (FEA) and response surface methodology (RSM). The RSM, that is a collection of the statistical and mathematical techniques, is utilized to predict the global optimal solution based on the FEA calculated results of the detect forces for different combinations of factors. With the help of the combination computation the high capacity iron-core type PMLSM with more than 12000 N propulsion forces only contains less than 3 N detent forces.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.179-184
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• 1995

A new cutting parameter is defined in the spherical part of ball end-mill cutter. A series of slot cutting experiments were carried out to obtain the cutting parameter. The cutter contact area is expressed as the grid posiotion in the cutting plane using Z map. The cutting forces in each grid are calculated and saved as force map, prior to the average cutting forces calculation. The cutting force, in the arbitrary cutting area, can be easily calculated by summing up the cutting forces of the engaged grid in the force map. This model was verified in the inclined surface cutting by cutting test of a cylindrical part.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.2.1-2.1
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• 2011

Electrospray deposition (ESD) technique is fast finding its applicability in the field of thin film device manufacturing processes and the ease and cost efficiency attached to ESD process with possible integration with batch manufacturing technologies is the potential future of thin film device manufacturing. As the name suggests, the deposition phenomenon should solely be a spray achieved through electrostatic forces. In fact it is an imbalance between the surface forces arising because of the surface tension of the liquid to be sprayed and Maxwell stresses which are induced because of the electric field, that pull the liquid downwards from the capillary into a stable jet which further disintegrates into smaller droplets because of coulomb forces and hence a cloud of charged, mono-dispersed and extremely diminutive (sometimes up to femtolitres) droplets is achieved. The present talk is going to be exclusively about the electrospray process concepts, generation and possible applications.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.16-21
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• 2004

As a new approach to analyze grinding energy, this paper introduces a specific grinding energy model based on the average grain. Using this model, grinding characteristics such as radial and tangential forces, specific grinding energy of SM45C were investigated altering grinding variables such as workpiece velocity(v) and apparent depth of cut(Z) in down-surface grinding. From the experimental results, there is no significant difference between the radial, tangential forces and vertical. horizontal forces because of small contact angle between wheel and workpiece. The specific grinding energy decreases as the maximum undeformed chip thickness increases. But, there is much difference between the specific grinding energies of the existing and the proposed model.

• 대한조선학회지
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• 제23권3호
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• pp.1-9
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• 1986

Herein the dynamic response of an axisymmetric buoy to regular wave is studied within linear potential theory. The buoy has a particular geometry so that it should experience minimum wave-exiting force on the vertical direction at a precribed wave number in water of finite depth. Invoking the Green's theorem a velocity potential is generated by distributing pulsating sources and doublets on the immersed surface of the buoy at its mean position. Hydrodynamic forces and moments are obtained approximately by summation of the products of linear pressure and directional mesh area over the immersed surface. Model tests are carried out to measure the wave-exciting forces, hydrodynamic forces and motion responses. The experimental results in general agree fairly well with the numerical ones. From the analytical and experimental works it is found that the pitching motion and its coupling effect affect significantly the motion characteristics of the freely-floating axisymmetric buoy in regular waves.

• 대한조선학회지
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• 제11권1호
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• pp.1-8
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• 1974

Hydrodynamic forces and moments produced by the swaying oscillation on the free surface were exactly calculated by Ursell-Tasai method for the cylinders with Kim's chine form sections and the sway responses of the cylinders of those chine form sections among the regular beam sea were also calculated. The results of the computation were compared with those of Lewis form sections. It is concluded that the effects of the section form on the added mass, and damping are small, if the section forms had same beam-draft ratio and sectional area coefficient in the case of sway motion. It is also known that the above little effects of section shapes on the basic hydrodynamic forces do not effect on the sway motion responses of cylinderical bodies among the regular beam sea. The sway motion responses of cylinderical bodies are varied linearly with the wave numbers.