• 한국지능시스템학회논문지
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• 제17권7호
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• pp.952-956
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• 2007

산업현장에서는 공장 자동화의 발전에 따라 많은 로봇들이 사람을 대신하고 있다. 일반적으로 산업 현장에서 사용되는 로봇은 고정밀도의 감속기를 필요로 한다. 고정밀의 제어를 위해서는 cycloid 치형 혹은 인벌류트 치형을 가진 감속기를 사용하게 된다. 이러한 감속기는 낮은 백래쉬와 높은 감속비를 가지면서 동시에 치형의 높은 강성을 필요로 한다. 본 논문에서는 새로이 고안한 직선 치형을 가진 로봇 감속기(RSR) 치형의강성을 FEM 해석을 통해 실제로 적용이 가능한지 여부를 시뮬레이션 해보았으며, 실제로도 적용이 가능함을 알 수 있었다.

• 대한치과교정학회지
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• 제49권2호
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• pp.116-123
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• 2019

As an alternative to the conventional fixed appliance that uses orthodontic brackets, a simple round tube without a bonding base can be bonded to the tooth surface by covering the tube with flowable resin. In this technique, bent wires cannot be inserted into the simple tubes; therefore, repositioning of the simple tubes is often required for adjustments. To reduce repositioning of simple tubes, a dome-shaped resin covering of the simple tube can be designed with a customized in-and-out compensation, using three-dimensional computer-aided design software based on digital simulation of orthodontic tooth movement. In the present case, the use of simple tubes bonded with customized resin coverings in a Class I nonextraction case is described in a 17-year-old male, in whom moderate crowding of the anterior teeth was treated over an 8-month period. This case shows that simple tubes can be used as an alternative to brackets in some Class I nonextraction cases, with the potential benefit of reducing decalcification.

• 전력전자학회논문지
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• 제17권6호
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• pp.478-485
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• 2012

In this paper, a new PWM method is proposed to reduce the input current harmonics of 3 phase PWM rectifier. In the conventional carrier comparison PWM method, a triangular wave is generally used as the carrier wave. However, the large d-axis current ripple by the triangle carrier wave may be a source of large input current THD(Total Harmonic Distortion). In this paper, a new carrier comparison PWM method with saw tooth wave is proposed. Depending on the sector where the voltage command vector places, one of the rising or falling saw tooth wave is selected. To reduce the switching losses of the saw tooth carrier PWM, the discontinuous PWM is also presented. The proposed PWM method can reduce the d-axis current ripple as well as the switching losses. The performance of the conventional and proposed PWM methods is verified by the simulation and experimental results.

• 한국생산제조학회지
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• 제20권1호
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• pp.101-107
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• 2011

Analytical solution of micro-scale milling process is presented in order to suggest available machining conditions. The size effect should be considered to determine cutting characteristics in micro-scale cutting. The feed per tooth is the most dominant cutting parameter related to the size effect in micro-scale milling process. In order to determine the feed per tooth at which chips can be formed, the finite element method is used. The finite element method is employed by utilizing the Johnson-Cook (JC) model as a constitutive model of work material flow stress. Machining experiments are performed to validate the simulation results by using a micro-machining stage. The validation is conducted by observing cutting force signals from a cutting tool and the conditions of the machined surface of the workpiece.

• Journal of Magnetics
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• 제22권1호
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• pp.133-140
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• 2017

Split magnetic fluid sealing is a combination of magnetic fluid rotary and plane sealing. Using the theory of equivalent magnetic circuit design as basis, the author theorized the pressure resistance performance of magnetic fluid plane sealing. To determine the pressure resistance of magnetic fluid plane sealing, the author adopted the method of finite element analysis to calculate the magnetic field intensity in the gap between plane sealing structures. The author also analyzed the effect of different sealing gaps, as well as different ratios between the sealing gap and tooth and solt width, on the sealing performance of split magnetic fluid. Results showed that the wider the sealing gap, the lower the sealing performance. Tooth width strongly affects sealing performance; the sealing performance is best when the ratio between tooth width and sealing gap is 2, whereas the sealing performance is poor when the ratio is over 8. The sealing performance is best when the ratio between the solt width and sealing gap is 4, indicating a slight effect on sealing performance when the ratio between the solt width and sealing gap is higher. Theoretical analysis and simulation results provide reference for the performance evaluation of different sealing equipment and estimation of critical pressure at interface failure.

• 한국자동차공학회논문집
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• 제13권1호
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• pp.140-146
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• 2005

This study presents the development of a round recliner using the finite element method. That reduces the number of test repeating times and gives an information about stiffness. A simulation model of round recliner mounting seat module and tooth strength simulation are established using a PAM-CRASH and ABAQUS. With the optimization of gear profile, structural strength design of round recliner was achieved. The round recliner seat module simulation, structure strength simulation and a crash safety are requested by FMVSS test. Solution of round recliner optimum variable study and design problem are searched for round recliner stress, deformation and application. Also an examination of safety is made.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.338-343
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• 2009

In this paper, Verification of the qualitatively identical relationships existing between simulation data and experimental results allowed for a new analysis procedure of a planetary gear set -- in an automatic transmission -- to be conducted. Tooth profiles were found to be crucial to the gear mesh forces of the planetary gear set. Based on Kahraman's Model[8], dynamic resonances of the planetary gear set were found to be out of operating range. Most importantly, a 2DPLANETARY FEM program, an innovative design tool for planetary gear sets, was utilized.

• 한국해양공학회지
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• 제28권6호
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• pp.560-565
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• 2014

In this study, the problem of trajectory optimization for underwater gliders considering depth constraints is discussed. Typically, underwater gliders are controlled to dive and climb in a saw-tooth pattern at constant gliding angles. This approach is effective and close to optimal for deep water applications. However, the optimal path deviates from the saw-tooth path in shallow water conditions. This study focuses on finding more efficient gliding paths that can minimize the traverse time in the horizontal plane when the water depth is limited. The trajectory optimization problem is formulated into a minimum time control problem with inequality path constraints and hydrodynamic drag effects. A numerical approach based on the pseudo-spectral method is adopted as a solution approach, and the simulation results are presented.

• Tribology and Lubricants
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• 제23권4호
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• pp.149-155
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• 2007

The CAD model of a elliptical gear for wire cutting has been developed. The rolling contact of pitch ellipses whose rotation axes coincide with their focus has been analyzed, and the perimeter of the pitch ellipse has been divided into equal-length segments by the number of teeth. A master tooth profile, which is a composite curve of circular arcs that represents involute, has been introduced. The elliptical gear has been designed by imposing the master tooth on the divided points of the pitch ellipse, and a full fillet has been achieved between neighbour teeth. Thus, the whole profile of an elliptical gear is a composite curve of arcs only, and consequently NC codes for wire cutting can be easily generated. Furthermore, a computer simulation program is developed to verify the mesh of the elliptical gear.

• 한국정밀공학회지
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• 제15권5호
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• pp.100-109
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• 1998

In order to increase productivity through unmanned machining in CNC milling process, in-process tool fracture detection is required. In this paper, a new algorithm for tool fracture detection using cutting load variations was developed. For this purpose, developed were tool condition vector which is dimensionless indicator of cutting load and tool fracture index (TFI) which represents magnitude of tool fracture. Through cutting force simulation, tool fracture index was shown to be independent of tool run-outs and cutting condition variations. Using tool fracture index, the ratio of the tool fracture to feed per tooth could be indentified.