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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 36, Issue 12 - Dec 2012
Volume 36, Issue 11 - Nov 2012
Volume 36, Issue 10 - Oct 2012
Volume 36, Issue 9 - Sep 2012
Volume 36, Issue 8 - Aug 2012
Volume 36, Issue 7 - Jul 2012
Volume 36, Issue 6 - Jun 2012
Volume 36, Issue 5 - May 2012
Volume 36, Issue 4 - Apr 2012
Volume 36, Issue 3 - Mar 2012
Volume 36, Issue 2 - Feb 2012
Volume 36, Issue 1 - Jan 2012
Selecting the target year
Evaluation of Moisture Sorption Characteristics in Polymer Material
Park, Hee-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1297~1303
DOI : 10.3795/KSME-A.2012.36.11.1297
In this paper, the standard procedures for measuring the moisture sorption properties of thin polymeric materials such as polyethylene terephthalate (PET) by using the thermo-gravimetric method to characterize the moisture diffusion in the polymer are presented, and the sorption properties are quantified. The moisture diffusivity and solubility are characterized to investigate the effect of temperature and humidity on the moisture sorption properties according to the Arrhenius equation. The validation of the obtained sorption properties using thermogravimetry is discussed with the measured permeability based on Fickian diffusion. The nonlinear behavior of the concentration dependent moisture diffusion is investigated experimentally, and the nonlinearity is characterized numerically for the case of having an interface with an inorganic material such as a metal. The Fickian/Non-Fickian model based on the obtained moisture sorption properties is compared and discussed.
Efficient Robust Design Optimization Using Statistical Moment Based on Multiplicative Decomposition Considering Non-normal Noise Factors
Cho, Su-Gil ; Lee, Min-Uk ; Lim, Woo-Chul ; Choi, Jong-Su ; Kim, Hyung-Woo ; Hong, Sup ; Lee, Tae-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1305~1310
DOI : 10.3795/KSME-A.2012.36.11.1305
The performance of a system can be affected by the variance of noise factors, which arise owing to uncertainties of the material properties and environmental factors acting on the system. For robust design optimization of the system performance, it is necessary to minimize the effect of the variance of the noise factors that are impossible to control. However, present robust design techniques consider the variation of design factors, and not the noise factors, as being important. Furthermore, it is necessary to assume a normal distribution; however, a normal distribution is often not suitable to estimate the variations. In this study, a robust design technique is proposed to consider the variation of noise factors that are estimated as non-normal distributions in a real experiment. As an example of an engineering problem, a deep-sea manganese nodule miner tracked vehicle is used to demonstrate the feasibility of the proposed method.
Design of a Robust Controller for Vehicle Rollover Prevention
Yim, Seong-Jin ; Kim, Yong-Moo ; Oh, Dong-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1311~1318
DOI : 10.3795/KSME-A.2012.36.11.1311
Vehicle systems are frequently exposed to parameter uncertainties such as vehicle speed and height of center of gravity. If a controller is designed to be robust against these parameter uncertainties, the rollover prevention capability can be considerably enhanced. In this study, robust controllers
are designed by using LMI for vehicle rollover prevention control in the discrete time domain. Some simulations using CarSim, a reliable simulation tool, are performed to validate the proposed controllers.
Study of Effect of Tractive Force on Bicycle Self-Stability
Souh, Byung-Yil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1319~1326
DOI : 10.3795/KSME-A.2012.36.11.1319
This study focuses on the influence of tractive forces on the self-stability of a bicycle. The eigen-value analysis of the self-stability of a passive rider control linear bicycle model can be used to analyze the self-stability. A linear bicycle model with front and rear driving forces is developed. The influence of tractive forces on the self-stability is identified by using the developed model. A nonlinear multi-body bicycle model is used to confirm the results of the linear analysis.
Conformance-Based Dynamic Performance Optimization of an Actuator
Son, Young-Kap ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1327~1334
DOI : 10.3795/KSME-A.2012.36.11.1327
This study shows the conformance-based design results of a fourth-order dynamic actuator showing a performance variation caused by variation in the components as well as aero-induced disturbances. The actuator comprises a BLDC motor, spur gear and worm gear assembly, and canard. The actuator performance was evaluated by using time-variant angle information of the canard. Based on the response surface models, critical system variables were screened using F-tests, and then, the performance was approximated as a function of the variables because it is difficult to determine the performance of a high-order dynamic system as a function of system variables through analytical approaches. In this study, the conformance of uncertain performance to the specification was defined as a probability measure. The design variables obtained by optimizing the measure can provide actuator performance conforming to the specifications considered, even though there is a variation in both the components and the aero-induced disturbances.
A Study on the Lightweight Design of Hybrid Modular Carbody Structures Made of Sandwich Composites and Aluminum Extrusions Using Optimum Analysis Method
Jang, Hyung-Jin ; Shin, Kwang-Bok ; Han, Sung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1335~1343
DOI : 10.3795/KSME-A.2012.36.11.1335
In this study, the lightweight modular design of hybrid railway carbody structures made of sandwich composites and aluminum extrusions was investigated by using topology and size optimization techniques. The topology optimum design was used to select the best material for parts of the carbody structure at the initial design stage, and then, the size optimum design was used to find the optimal design parameters of hybrid carbody structures using first-order and sub-problem methods. Through the topology optimization analysis, it was found that aluminum extrusions were suitable for primary members such as the underframe and lower side panel module to improve the stiffness and manufacturability of the carbody structures, and sandwich composites were appropriate for secondary members such as the roof and middle side panel module to minimize its weight. Furthermore, the results obtained by size optimization analysis showed that the weight of hybrid carbody structures composed of aluminum extrusions and sandwich composites could be reduced by a maximum of approximately 17.7% in comparison with carbody structures made of only sandwich composites.
Evaluation of Mechanical Properties and Low-Velocity Impact Characteristics of Balsa-Wood and Urethane-Foam Applied to Impact Limiter of Nuclear Spent Fuel Shipping Cask
Goo, Jun-Sung ; Shin, Kwang-Bok ; Choi, Woo-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1345~1352
DOI : 10.3795/KSME-A.2012.36.11.1345
This paper aims to evaluate the low-velocity impact responses and mechanical properties of balsa-wood and urethane-foam core materials and their sandwich panels, which are applied as the impact limiter of a nuclear spent fuel shipping cask. For the urethane-foam core, which is isotropic, tensile, compressive, and shear mechanical tests were conducted. For the balsa-wood core, which is orthotropic and shows different material properties in different orthogonal directions, nine mechanical properties were determined. The impact test specimens for the core material and their sandwich panel were subjected to low-velocity impact loads using an instrumented testing machine at impact energy levels of 1, 3, and 5 J. The experimental results showed that both the urethane-foam and the balsa-wood core except in the growth direction (z-direction) had a similar impact response for the energy absorbing capacity, contact force, and indentation. Furthermore, it was found that the urethane-foam core was suitable as an impact limiter material owing to its resistance to fire and low cost, and the balsa-wood core could also be strongly considered as an impact limiter material for a lightweight nuclear spent fuel shipping cask.
Analysis of Jacobian and Singularity of Planar Parallel Robots Using Screw Theory
Choi, Jung-Hyun ; Lee, Jeh-Won ; Lee, Hyuk-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1353~1360
DOI : 10.3795/KSME-A.2012.36.11.1353
The Jacobian and singularity analysis of parallel robots is necessary to analyze robot motion. The derivations of the Jacobian matrix and singularity configuration are complicated and have no geometrical earning in the velocity form of the Jacobian matrix. In this study, the screw theory is used to derive the Jacobian of parallel robots. The statics form of the Jacobian has a geometrical meaning. In addition, singularity analysis can be performed by using the geometrical values. Furthermore, this study shows that the screw theory is applicable to redundantly actuated robots as well as non-redundant robots.
Shape Optimization of Metal Forming and Forging Products using the Stress Equivalent Static Loads Calculated from a Virtual Model
Jang, Hwan-Hak ; Jeong, Seong-Beom ; Park, Gyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1361~1370
DOI : 10.3795/KSME-A.2012.36.11.1361
A shape optimization is proposed to obtain the desired final shape of forming and forging products in the manufacturing process. The final shape of a forming product depends on the shape parameters of the initial blank shape. The final shape of a forging product depends on the shape parameters of the billet shape. Shape optimization can be used to determine the shape of the blank and billet to obtain the appropriate final forming and forging products. The equivalent static loads method for non linear static response structural optimization (ESLSO) is used to perform metal forming and forging optimization since nonlinear dynamic analysis is required. Stress equivalent static loads (stress ESLs) are newly defined using a virtual model by redefining the value of the material properties. The examples in this paper show that optimization using the stress ESLs is quite useful and the final shapes of a forming and forging products are identical to the desired shapes.
Vibration Identification of Gasoline Direct Injection Engine Based on Partial Coherence Function
Chang, Ji-Uk ; Lee, Sang-Kwon ; Park, Jong-Ho ; Kim, Byung-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1371~1379
DOI : 10.3795/KSME-A.2012.36.11.1371
This paper presents a method for estimating the contribution of vibration sources in gasoline direct injection engine parts with a multiple-input system. A partial coherence function was used to identify the cause of the linear dependence indicated by an ordinary coherence function. To apply the partial coherence function to vibration source identification in the powertrain system of a gasoline direct injection engine, a virtual model of a two-input and single-output system is simulated. For the validation of this model, the vibration of the powertrain parts was measured by using triaxial accelerometers attached to the selected vibration sources-a high-pressure pump, fuel rail, injector, and pressure sensor. After calculating the partial coherence between each source based on the virtual model, the vibration contribution of the powertrain system is calculated. This virtual model based on the partial coherence function is implemented to determine the quantitative vibration contribution of each powertrain part.
Microscopic Analysis of Effect of Shot Peening on Corrosion Fatigue Behavior of Aluminum Alloy
Kim, Jong-Cheon ; Cheong, Seong-Kyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1381~1389
DOI : 10.3795/KSME-A.2012.36.11.1381
The object of this study considers corrosion fatigue improvement of 7075-T6 aluminum by using shot peening treatment on 3.5% NaCl solution at room temperature. Aluminum alloy is generally used in aerospace structural components because of the light weight and high strength characteristics. Many studies have shown that an aluminum alloy can be approximately 50% lighter than other materials. Mostly, corrosion leads to earlier fatigue crack propagation under tensile conditions and severely reduces the life of structures. Therefore, the technique to improve material resistance to corrosion fatigue is required. Shot peening technology is widely used to improve fatigue life and other mechanical properties by induced compressive residual stress. Even the roughness of treated surface causes pitting corrosion, the compressive residual stress, which is induced under the surface layer of material by shot peening, suppresses the corrosion and increases the corrosion resistance. The experimental results for shot peened specimens were compared with previous work for non treated aluminum alloy. The results show that the shot peening treatment affects the corrosion fatigue improvement of aluminum alloys and the induced compressive residual stress by shot peening treatment improves the resistance to corrosion fatigue.
Contact Fatigue Life for CRG System
Nam, Hyoung-Chul ; Kim, Chang-Hyun ; Kwon, Soon-Man ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1391~1397
DOI : 10.3795/KSME-A.2012.36.11.1391
A cam ring gear (CRG) system based on a hypotrochoid curve consists of a pinion with roller teeth and its conjugated internal CRG. In this study, we investigated contact forces, contact stresses, and load stress factors to predict the surface pitting life using an exact CRG profile by introducing the profile modification coefficient. The results show that the pitting life can be extended significantly by increasing the profile modification coefficient without any other change of parameters in the CRG system.
A Study on Accurate Alignment Measurement of Dual Thruster Module Using Theodolite
Hwang, Kwon-Tae ; Moon, Guee-Won ; Cho, Chang-Lae ; Lee, Dong-Woo ; Lee, Sang-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1399~1404
DOI : 10.3795/KSME-A.2012.36.11.1399
Because satellites operate in space, it is impossible to repair them when they malfunction. Therefore, to ensure the normal function of the payload used in the satellites, accurate assembly and installation of parts are crucial. To prevent abnormal functioning in the extreme environments during launch and in space, it is essential to test changes at the parts and system levels by performing alignment measurement before and after the launch environment test and the space environment test. Recently, noncontact three-dimensional precision machinery for medium- and large-sized parts has been developed. One of these is the theodolite measurement system, which is widely used in the aerospace industry. This study measures the angle of the dual thruster module that is used to control the attitude of KOMPSAT by using a theodolite, and alignment measurement and a reliability analysis are performed.
Stiffness Analysis of Spring Mechanism for Semi-Automatic Gripper Motion of Tendon-Driven Remote Manipulator
Yu, Seung-Nam ; Lee, Jong-Kwang ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1405~1411
DOI : 10.3795/KSME-A.2012.36.11.1405
Remote handling manipulators are widely used for performing hazardous tasks, and it is essential to ensure the reliable performance of such systems. Toward this end, tendon-driven mechanisms are adopted in such systems to reduce the weight of the distal parts of the manipulator while maintaining the handling performance. In this study, several approaches for the design of a gripper system for a tendon-driven remote handling system are introduced. Basically, this gripper has an underactuated spring mechanism that is combined with a slave manipulator triggered by a master operator. Based on the requirements under the specified tendon-driven mechanism, the connecting position of the spring system on the gripper mechanism and kinematic influence coefficient (KIC) analysis are performed. As a result, a suitable combination of components for the proper design of the target system is presented and verified.
An Analysis of Running Stability of 1/5 Small Scaled Bogie on Small-Scaled Derailment Simulator
Eom, Beom-Gyu ; Kang, Bu-Byoung ; Lee, Hi-Sung ; Song, Moon-Shuk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1413~1420
DOI : 10.3795/KSME-A.2012.36.11.1413
To predict the dynamics behavior, running stability, etc. of a railway vehicle and to understand its physical characteristics, analytical methods are used for the testing and manufacturing of a scale model along with numerical simulations in developed countries (England, France, Japan, etc.). The test of the dynamics characteristics of full-scale models is problematic in that it is expensive and time-consuming because an entire large-scale test plant needs to be constructed, difficulties are involved in the test configuration, etc. To overcome these problems, an analytical study involving dynamics tests and computer simulations using a scaled bogie model that applies the laws of similarity was carried out. In this study, we performed stability analysis on a 1/5 small scaled bogie for parameters such as the running speed and carbody weight by using an analysis model. Furthermore, we verified the reliability by using a small-scaled derailment simulator and examined the dynamic characteristic of the 1/5 small scaled bogie.
Study on Vehicle Dynamics Performance Evaluation of Electric Active Roll Control System for SUV
Jeon, Kwang-Ki ; Choi, Sung-Jin ; Kim, Joon-Tae ; Yi, Kyong-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1421~1426
DOI : 10.3795/KSME-A.2012.36.11.1421
Cornering maneuvers with reduced body roll and without comfort loss are important requirements for car manufacturers. An electric active roll control(ARC) system controls the body roll angle by using motor-driven actuators installed at the centers of the front and rear stabilizer bars. Co-simulation using the Matlab/Simulink controller model and the CarSim vehicle model was proposed to evaluate the performance of the ARC control algorithm. To validate the performance of the ARC actuator and system, bench tests and vehicle tests were proposed.
Individual Pitch Control of NREL 5MW Wind Turbine Blade for Load Reduction
La, Yo-Han ; Nam, Yoon-Su ; Son, Jae-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1427~1432
DOI : 10.3795/KSME-A.2012.36.11.1427
As the size of a wind turbine increases, the rotor diameter increases. Rotor blades experience mechanical loads caused by the wind shear and the tower shadow effect. These mechanical loads reduce the life of the wind turbine. Therefore, with increasing size of the wind turbine, wind turbine control system design for the mitigation of mechanical loads is important. In this study, Individual Pitch Control in introduced for reducing the mechanical loads of rotor blades, and a simulation for IPC performance verification is discussed.
Development of Sensor System for Indoor Location-Based Service Implementation
Cha, Joo-Heon ; Lee, Kyung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1433~1439
DOI : 10.3795/KSME-A.2012.36.11.1433
This paper introduces a sensor system based on indoor locations in order to implement the Building Energy Management System. This system consists of a thermopile sensor and an ultrasonic sensor. The sensor module is rotated by
and yawed up-and-down by two electric motors. Therefore, it can simultaneously detect the number and location of the inhabitants in the room. It uses wireless technology to communicate with the building manager or the smart-home server, and it can save electric energy by controlling the lighting system or heating/air conditioning equipment automatically. We also demonstrate the usefulness of the proposed system by applying it to a real environment.
Analysis of Performance Characteristics of Swash-Plate-Type Hydraulic Piston Motor
Lee, Yong-Bum ; Kim, Kwang-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1441~1446
DOI : 10.3795/KSME-A.2012.36.11.1441
An axial-piston-type hydraulic motor involves friction and leakage losses at the sliding parts, contact loss at the mechanism assembly parts, volumetric loss caused by the pressure drop, housing oil churning loss and compressibility from the hydraulic oil pipe resistance, etc. the friction and volumetric loss at the hydrostatic bearing between the piston shoe and the swash plate rotating at high speed and having an oil film gap of 8-15
strongly affects the total efficiency of the hydraulic motor. In this study, a variable swash-plate-type hydraulic piston motor operating under a maximum pressure of 35 MPa, maximum speed of 2,500 rpm, and displacement of 320 cc/rev is tested to verify the optimal ratio of the hydrostatic bearing which is closely related to the hydraulic motor performance.
Lateral Vibration Reduction of a Maglev Train Using U-shaped Electromagnets
Han, Jong-Boo ; Kim, Ki-Jung ; Han, Hyung-Suk ; Kim, Sung-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1447~1453
DOI : 10.3795/KSME-A.2012.36.11.1447
For an electromagnetic suspension (EMS)-type urban Maglev train using U-shaped electromagnets, both the vertical and the lateral air gaps for levitation are maintained only by the electromagnet. The train can run over curved rails without active lateral air gap control because the U-shaped electromagnet simultaneously produces both a levitation force and a guidance force, which is dependent on the levitation force. Owing to the passive control of the lateral air gap, the lateral vibration could exceed the limits of the lateral air gap and acceleration. In this study, dynamic analysis of a Maglev train is carried out, and the effectiveness of a lateral damper for vibration reduction is investigated. To more accurately predict the lateral vibration, a Maglev vehicle multibody model including air-sparing, guideway irregularities, electromagnets, and their controls is developed.
Mitigation of Mechanical Loads of NREL 5 MW Wind Turbine Tower
Nam, Yoon-Su ; Im, Chang-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1455~1462
DOI : 10.3795/KSME-A.2012.36.11.1455
As the size of a wind turbine increases, the mechanical structure has to have an increasing mechanical stiffness that is sufficient to withstand mechanical fatigue loads over a lifespan of more than 20 years. However, this leads to a heavier mechanical design, which means a high material cost during wind turbine manufacturing. Therefore, lightweight design of a wind turbine is an important design constraint. Usually, a lightweight mechanical structure has low damping. Therefore, if it is subjected to a disturbance, it will oscillate continuously. This study deals with the active damping control of a wind turbine tower. An algorithm that mitigates the mechanical loads of a wind turbine tower is introduced. The effectiveness of this algorithm is verified through a numerical simulation using GH Bladed, which is a commercial aero-elastic code for wind turbines.
Verification of Camera-Image-Based Target-Tracking Algorithm for Mobile Surveillance Robot Using Virtual Simulation
Lee, Dong-Youm ; Seo, Bong-Cheol ; Kim, Sung-Soo ; Park, Sung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1463~1471
DOI : 10.3795/KSME-A.2012.36.11.1463
In this study, a 3-axis camera system design is proposed for application to an existing 2-axis surveillance robot. A camera-image-based target-tracking algorithm for this robot has also been proposed. The algorithm has been validated using a virtual simulation. In the algorithm, the heading direction vector of the camera system in the mobile surveillance robot is obtained by the position error between the center of the view finder and the center of the object in the camera image. By using the heading direction vector of the camera system, the desired pan and tilt angles for target-tracking and the desired roll angle for the stabilization of the camera image are obtained through inverse kinematics. The algorithm has been validated using a virtual simulation model based on MATLAB and ADAMS by checking the corresponding movement of the robot to the target motion and the virtual image error of the view finder.
Development of Fracture-Type Protector for a Launching Reconnaissance Robot
Kang, Bong-Soo ; Cho, Yoon-Ho ; Choi, Jeong-Nam ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1473~1478
DOI : 10.3795/KSME-A.2012.36.11.1473
This paper presents the development of a fracture-type protector for carrying a reconnaissance robot to a remote target area. Instead of a conventional unlocking mechanism, a separation method based on the fracture of assembled parts was implemented in the proposed lightweight protector in order to improve the feasibility for a real battlefield. Simulations using the finite element model of the protector and the robot were performed to verify the fracture under the given loading conditions, and shock experiments using a drop table were performed to calculate shock transmittance through the protector to the robot. Several field tests for a 100-m flight proved that the proposed scenario (launching, flying, landing, and separation) was achieved successfully.
Curvature Estimation Method of Curve Section Using Relative Displacement Between Body and Bogie of Rolling-stock
Hur, Hyun-Moo ; Park, Joon-Hyuk ; You, Won-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 11, 2012, Pages 1479~1485
DOI : 10.3795/KSME-A.2012.36.11.1479
The development of a technique for the real-time sensing of a curve section is very important for active rolling-stocks in order to improve the curving performance. However, conventional methods using expensive track inspection equipment or various complex sensors are not practicable to be applied to commercial vehicles. Therefore, we have proposed a new method to estimate the curve radius of a curve section. This method uses the relative displacements occurring between the body and the bogie when the rolling-stock is running on a curve. To verify the validity of this method, we conducted a vehicle dynamics simulation and test using a real vehicle on a test line. The results confirmed the validity of the proposed method. We expect that this method will be effectively applied in studies of active rolling-stocks to increase the curving performance using active control technology.