• Journal of Power Electronics
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• 제13권4호
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• pp.536-545
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• 2013

In this study, an integrated motor control algorithm for an in-wheel electric vehicle is suggested. It consists of slip control that controls the in-wheel motor torque using the road friction coefficient and slip ratio; yaw rate control that controls the in-wheel motor torque according to the road friction coefficient and the yaw rate error; and velocity control that controls the vehicle velocity by a weight factor based on the road friction coefficient and the yaw rate error. A co-simulator was developed, which combined the vehicle performance simulator based on MATLAB/Simulink and the vehicle model of CarSim. Based on the co-simulator, a human-in-the-loop simulation environment was constructed, in which a driver can directly control the steering wheel, the accelerator pedal, and the brake pedal in real time. The performance of the integrated motor control algorithm for the in-wheel electric vehicle was evaluated through human-in-the-loop simulations.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.390-395
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• 2004

The characteristics of the circular arc shaped multi-blade windmil are investigatedl. The prototypical windmill was tested in the laboratory at wind tunnel speeds of 5.5, 9.4m/s. and the model windmill was also tested in the laboratory, The power and torque coefficients were studied as functions of the blade section, the aspect ratio for blade diameter and windmill radius(M = 0.3, 0.5, 0.7), the number of blades and finally the tip-speed ratio. The analysis of the experimental results for the model windmill showed that there is the highest revolutions per minute(R.P.M) at the circular arc shaped multi-blade windmill having the blade number 10, aspect ratio(M = 0.7). and the results for the prototypical windmill showed that the power coefficient increased to a maximum value and then decreased again with an increase in the tip speed ratio, while the torque coefficient decreased directly with an increase in the tip speed ratio Finally, the experimental results were compared with the Savonius blade. the maximum power coefficient for the arc shaped blade was greater than for the Savonius blade and occured at a lower tip speed ratio.

• 한국정밀공학회지
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• 제29권2호
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• pp.170-177
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• 2012

A force/torque sensor using carbon fiber plate was designed and developed to make the sensor be able to measure a wide range of multi degree of force and torque. Using carbon fiber plate of 0.3 mm thickness, the sensor was designed and developed, which has a ${\mu}N$ level order of resolution and about 0.01 N ~ 390 N of wide measurement range. The elastic deformation part has a tripod plate structure and strain gauges are attached on the part to detect the force/torque. The coefficient of determination for the sensor is over 0.955 by the calibration experiment so that the linearity of the sensor is confirmed to be good. Also, experiments on applying 0.005 ~ 40 kg (0.05 ~ 390 N) to each axis were implemented and the sensor is proved to be safe under a high load. Finally, to verify the function calculating the direction of load vector, the directions of various load vectors which have the same magnitude but different directions and the directions of the calculated load vectors are compared and analyzed to accord well.

• Journal of Power Electronics
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• 제16권1호
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• pp.249-258
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• 2016

Given that elastic connection is often used between motor drives and load devices in industrial applications, vibration often occurs at the load side. Vibration suppression is a crucial problem that needs to be addressed to achieve a high-performance servo-control system. Scholars have presented many strategies to suppress vibration. In this study, we propose a method to diminish vibration by using a torque feed-forward and disturbance torque observer. We analyze the system performance and explain the principle of the proposed vibration suppression method based on the transfer functions of the system. The design of controller parameters is another important issue in practical applications. We accordingly provide a succinct outline of the design specifications based on the coefficient diagram method. Furthermore, we build a model under the Simulink environment and conduct experiments to validate the proposed method. Results show that speed and position vibrations are successfully suppressed by the proposed method.

• Structural Engineering and Mechanics
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• 제53권5호
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• pp.939-956
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• 2015

In this study, in order to propose an efficient model to predict the torque capacity of steel fiber reinforced concrete (SFRC) beams, the existing experimental data related to torsional response of beams is reviewed. It is observed that existing data neglects the effects of some parameters on the variation of torque capacity. Thus, an experimental research was also conducted to obtain the effects of neglected parameters. In the experimental study, a total of seventeen SFRC beams are tested against torsion. The parameters considered in the experiments are concrete compressive strength, steel fiber aspect ratio, volumetric ratio of steel fibers and longitudinal reinforcement ratio. The effect of each parameter is discussed in terms of torque versus unit angle of twist graphs. The data obtained from this experimental research is also combined with the data got from previous studies and employed in artificial neural network (ANN) analysis to estimate the ultimate torque capacity of SFRC beams. In addition to parameters considered in the experiments, aspect ratio of beam cross-section, yield strengths of both transverse and longitudinal reinforcements, and transverse reinforcement ratio are also defined as parameters in ANN analysis due to their significant effects observed in previous studies. Assessment of the accuracy of ANN analysis in estimating the ultimate torque capacity of SFRC beams is performed by comparing the analytical and experimental results. Comparisons are conducted in terms of root mean square error (RMSE), mean absolute error (MAE) and coefficient of efficiency ($E_f$). The results of this study revealed that addition of steel fibers increases the ultimate torque capacity of reinforced concrete beams. It is also found that ANN is a powerful method and a feasible tool to estimate ultimate torque capacity of both normal and high strength concrete beams within the range of input parameters considered.

• 한국강구조학회 논문집
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• 제20권3호
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• pp.399-407
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• 2008

건축공사 표준시방서에서 규정하는 TS고력볼트는 KS B 2819에 따라 토크관리법에 의한 체결한다. TS고력볼트는 핀 테일이 파단되면 적정축력이 도입되는 것으로 알려져 있지만, 실제로는 온도조건에 따라 토크계수가 변하고 도입축력도 설계기준에 미치지 못하는 경우가 발생한다. 본 논문에서는 현장 온도조건이 볼트의 토크계수 및 도입축력의 영향을 평가하기 위해 ${-10^{\circ}C{\sim}50^{\circ}C}$ 범위에서 3 종류의 고력 볼트에 대해 도입축력, 토크계수, 너트회전각을 실험적으로 비교 분석하였다. 실험결과 TS고력볼트의 경우 핀 테일이 파단될 때 모든 온도조건에서 설계볼트장력과 표준볼트장력을 상회하는 도입축력을 나타냈으며 ${-10^{\circ}C}$에서 ${50^{\circ}C}$까지 온도 상승함에 따라 핀 테일 파단시점의 볼트에 도입되는 평균축력은 20kN 증가되었다. 아연피막 처리한 일반육각형 고력볼트의 경우, $0^{\circ}C$, $20^{\circ}C$, $50^{\circ}C$조건, 토크계수 0.13과 토크 ${462N{\cdot}m} $에서 표준볼트축력을 상회하였지만, 도입축력의 일정한 경향을 찾을 수 없었으며 온도변수 별 평균 도입축력 차는 최대 50kN이었다. 일반 육각고력볼트의 경우, 온도상승에 따라 평균 도입축력도 상승되는 추세였으며 토크 ${462N{\cdot}m} $ 일때 온도변수별 볼트의 도입축력은 최대 33kN 차이를 보였다. 또한, TS볼트를 제외한 육각볼트 종류 군에 대해서는 너트회전각 ${90^{\circ}}$ 경우의 도입축력은 설계볼트장력에 미치지 못했다. 따라서, 기존 너트회전각 ${120^{\circ}{\pm}30^{\circ}}$의 하한치 ${-30^{\circ}}$에 대한 재평가를 고려해 볼 필요가 있다.

• Structural Engineering and Mechanics
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• 제32권4호
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• pp.477-488
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• 2009

A slip critical joint has various values to adopt the proper slip coefficient in various conditions of faying surfaces in the following codes: AISC, AIJ and Eurocode 3. However, the Korean Building Code still regulates the unique slip coefficient, 0.45, regardless of the diverse faying conditions. In this study, the slip resistance test, including five kinds of surface treatments were conducted to obtain the proper slip coefficients available to steel plate KS SM490A. The faying surfaces were comprised of a clean mill, rust, red lead paint, zinc primer, and shot blast treatment. The candidates for high strength bolts were torque-shear bolts, torque-shear bolts with zinc coating, and ASTM A490 bolts. Based on the test results, the specimens with a shot blasted surface and rusted surface exhibited $k_s$, 0.61, and 0.5, respectively. It is recommended that the specimens with zinc primer exhibit $k_s{\geq}0.40$. The clean mill treated surface had prominently lower values, 0.27. For red lead painted treatment, the thickness of the coating affects the determinant of slip coefficient, so it is necessary to establish a minimum $k_s$ of 0.2, with a coating thickness of 65 ${\mu}m$. During 1,000 hours of relaxation, the uncoated surfaces exhibited the loss of clamping force behind 3%, while the coated surfaces within a certain limited thickness exhibited the loss of clamping within a range of 4.71% and 8.37%.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.214-219
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• 2003

This paper includes real-time tractive force estimation method using standard vehicle sensors such as wheel speed, brake pressure, throttle position, engine speed, and transmission carrier speed sensor. Engine map, torque converter lookup table, shaft torque observer, and brake gain adaptation method are used to estimate the tractive force. To verify this estimator, measurement which uses strain-based brake torque sensor and estimation results are presented. All results was performed using a real vehicle in a real-time.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권6호
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• pp.655-667
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• 2017

The results of a numerical study on the performance of a propeller operating near a free surface are presented. The numerical simulations were performed for the various advance coefficients and the submergence depths of the model propeller. The effects of the model propeller size were investigated using two different model propeller sizes for all cases. The wave pattern of the free surface and the flow structure around the propeller as well as the hydrodynamic characteristics of the propeller were investigated through simulation results. The thrust and torque fluctuated and the trajectory of the tip vortex was distorted due to the interaction with the free surface. The wave pattern of the free surface was related to the tip vortex of the propeller. The decreases in thrust and torque at the small model propeller were greater than those of the large model propeller. The reduction rate of the thrust and torque increased with the advance coefficient.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.101-116
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• 2002

Modern vehicles require a high degree of refinement, including good driveability to meet customer demands. Vehicle driveability, which becomes a key decisive factor for marketability, is affected by many parameters such as engine control and the dynamic characteristics in drive lines. Therefore, Engine and drive train characteristics should be considered to achieve a well balanced vehicle response simultaneously. This paper describes analysis procedures using a mathematical model which has been developed to simulate spark timing control logic. Inertia mass moment, stiffness and damping coefficient of engine and drive train were simulated to analyze the effect of parameters which were related vehicle dynamic behavior. Inertia mass moment of engine and stiffness of drive line were shown key factors for the shuffle characteristics. It was found that torque increase rate, torque reduction rate and torque recovery timing and rate influenced the shuffle characteristics at the tip-in condition for the given system in this study.