• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.12
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• pp.659-663
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• 2002

The brake systems of high-speed train are to be equipped with three different brake systems, such as regenerative brake with regenerative feedback in driving car, a pneumatic disc brake, and non-contact linear eddy-current brake(ECB). The regenerative brake and the pneumatic disc brake are acting on the wheels. Their achievable braking force depends on the adhesive coefficient, which is influenced by the weather condition and speed, between the wheel and The linear eddy current brake gets an economical solution in the high-speed train because of the independence of the adhesive coefficient, no maintenance needed. and the good control characteristics. The braking force and the normal force of ECB for korean high-speed train are analysed by the 2D FEM(Finite Element Method). Finally the normal force is compared with the experiential values to verify the analysis.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.5
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• pp.373-379
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• 2016

Hydraulic forces on a vessel are changed according to the depth/draft ratio (h/d) during berthing or towing in a lateral direction. It is well known that lateral current force coefficient is dependent on the kinds of vessel in question. However, not much research exists about the characteristics of general ships, except for oil tankers, as suggested by the Oil Companies International Marine Forum (OCIMF). In this paper, lateral current coefficient related to h/d is analyzed in comparison with theoretical values and experiments with a 93m passenger ship. The estimated total resistance on the ship was 14.0 tons under an h/d of 1.6 with a lateral current force coefficient of 1.9. This was found to be similar to the measured value of 13.8 tons on the towing line in actual experiments. Resistances on the ship under an h/d of 3.0 was calculated to be 19.9 tons with a lateral current force coefficient of 1.3. Therefore, the lateral current force coefficient was expected to be 1.3 under an h/d of 3.0, in experiments measured value 20.0 tons. And the discharging currents did not affect the towing force if the towing line was over 30 m, since the towing resistance showed a similar tendency for changes in line length from 30 m to 60 m.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.7-10
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• 2007

The current model based sensorless method has many benefits that it can be robust control for large load torque. However, this method should determine a coefficient of back electro motive force(back-emf). This coefficient is varied by load torque and speed. Also, the coefficient determining equation is not exist, so it is determined only by experiment. On the other hands, using only back-emf estimatior method can not drive in low speed area and it has weakness in load variation. For these problems, this paper suggests the hybrid sensorless method that mixes the back-emf estimator regarding saliency and the current based sensorless model. This estimator offers not only non-necessary coefficient for current sensorless model, but also wide speed area operating in no specific transition method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.5
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• pp.445-455
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• 2013

A new linearization model for MR dampers is analyzed. The nonlinear hysteretic damping force model of MR damper can be modeled as a hyperbolic tangent function of currents, positions, and velicities, which is an algebraic function with constant parameters. Model parameters can be identified with numerical method using experimental force-velocity-position data obtained from various operating conditions. The nonlinear hysteretic damping force can be linearized with a given slope of damping coefficient if there exist corresponding currents to compensate for the nonlinearity. The corresponding currents can be calculated from the inverse model when the given linear damping force is set equal to the nonlinear hysteretic damping force. The linearization controller is realized in a DSP controller such that the corresponding currents to satisfy a given damping coefficient should be calculated. Experiments show that the current inputs to the MR damper produce linearized damping force with a given slope of the damping coefficient.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.512-519
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• 2016

In this study, the tire road friction estimation(TRFE) algorithm for controlling the rear wheel driving force of a 4WD vehicle during acceleration is developed using a standard sensor in an ordinary 4WD passenger car and a speed sensor. The algorithm is constructed for the wheel shaft torque, longitudinal tire force, vertical tire force and maximum tire road friction estimation. The estimation results of shaft torque and tire force were validated using a torque sensor and wheel force transducer. In the algorithm, the current road friction is defined as the proportion calculated between longitudinal and vertical tire force. Slip slop methods using current road friction and slip ratio are applied to estimate the road friction coefficient. Based on this study's results, the traction performance, fuel consumption and drive shaft strength performance of a 4WD vehicle are improved by applying the tire road friction estimation algorithm.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.6
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• pp.82-87
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• 2014

Small MR dampers with a simple structure were designed and manufactured. The Bingham model was used to represent the dynamic characteristics of the damper, and the parameters of the model were estimated from experimental data which were obtained by harmonic tests. The value of the estimated yield shear force remains positive when no electric current is applied, and it increases slowly with the current. The estimated viscous damping coefficient has a value close to zero when no electric current is applied, and it increases almost linearly with the current.

• Wind and Structures
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• v.14 no.1
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• pp.1-14
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• 2011

Open frame structures, such as those commonly found in industrial process facilities, are often densely occupied with process related equipment. This paper presents a method for estimating wind loads for high-solidity open frame structures that differs from current approaches, which accumulate wind load contributions from various individual structure components. The method considers the structure as a porous block of arbitrary plan dimension that is subject to wind from any direction. The proposed method compares favorably with wind tunnel test results for similar structures. The possibility of defining an upper bound force coefficient is also discussed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.8
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• pp.1055-1061
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• 2018

Recently, due to the rapid development of electric vehicle and energy storage system, it is emphasized for battery management system to be needed and to be improved. BMS carries out various movement for optimization the use of the energy and safe use of secondary battery, these movement of BMS start at high wattage shunt fixed resistor which performs a function for detecting current among the BMS components. In addition, for the safe operation of secondary battery, the reliability of current voltage variation detected from shunt should be secured, and for corresponding characteristics, the quality of Temperature coefficient of resistance for BMS shunt and the quality of Thermo electromotive force all must be excellent. For these reasons, this study comes up with the stabilization plan for thermo electromotive force and temperature coefficient of resistance of BMS shunt resistor which is key to secondary battery operation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.250-254
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• 2008

Eddy currents are induced when a nonmagnetic conductive material is moving subjected to the magnetic field due to a permanent magnet. These currents circulates in the conductive material and are dissipated, causing a repulsive force between the magnet and the conductor. Using this concept, the eddy current damping can be used as a viscous damping. The present study investigates the characteristics of a magnetic damping analytically and experimentally. The theoretical model of a eddy current damping is developed from electromagnetics and is verified from experiments. The drop test of a magnet in the cooper tube shows that the present model can accurately predict the damping force. Additionally, the dynamic test of a eddy current damping is carried to verify the present model.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.491-500
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• 2020

The present study proposes a time domain model for the Vortex-induced Vibration (VIV) simulation of a catenary riser under the combination of the current and oscillatory flow induced by vessel motion. In this model, the hydrodynamic force of VIV comprises excitation force, hydrodynamic damping and added mass, which are taken as functions of the non-dimensional frequency and amplitude ratio. The non-dimensional frequency is related with the response frequency, natural frequency, lock-in range and the fluid velocity. The relatively oscillatory flow induced by vessel motion is taken into account in the fluid velocity. Considering that the added mass coefficient and the non-dimensional frequency can affect each other, an iterative analysis is conducted at each time step to update the added mass coefficient and the natural frequency. This model is in detail validated against the published test models. The results show that the model can reasonably reflect the effect of the added mass coefficient on the VIV, and can well predict the riser's VIV under stationary and oscillatory flow induced by vessel motion. Based on the model, this study carries out the VIV simulation of a catenary riser with harmonic vessel motion. By analyzing the bending moment near the touchdown point, it is found that under the combination of the ocean current and oscillatory flow the vessel motion may decrease the VIV response, while increase the excited frequencies. In addition, the decreasing rate of the VIV under vessel surge is larger than that under vessel heave at small vessel motion velocity, while the situation becomes opposite at large vessel motion velocity.