• Journal of Korean Society for Quality Management
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• v.31 no.4
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• pp.164-175
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• 2003

This paper investigates bootstrap confidence intervals of the process capability index(PCI) based on the expected loss derived from the empirical distribution function(EDF). The PCI based on the expected loss is too complex to derive its confidence interval analytically, so the bootstrap method is a good alternative. We propose three types of the bootstrap confidence interval; the standard bootstrap(SB), the percentile bootstrap(PB), and the acceleration biased­corrected percentile bootstrap(ABC). We also perform a comprehensive simulation study under various process distributions, in order to compare the accuracy of the coverage probability of the bootstrap confidence intervals. In most cases, the coverage probabilities of the bootstrap confidence intervals from the EDF PCI turned out to be more accurate than those from the PCI based on the normal distribution. It is expected that the bootstrap confidence intervals from the EDF PCI can be utilized in real processes where the true distribution family may not be known.

• Water for future
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• v.26 no.4
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• pp.61-71
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• 1993

To investigate the structure of internal flow hydrodynamically, the complete vertical equation of motion should be assembled into the model. In the present study a numerical simulation model not hydrodynamically approximated is established. From the comparison of the predicted results with the computed results from k-$ two equation turbulence model by Huh et. al.(1991)and the experimental data by Nakatsuji(1984), the vertical acceleration and its effects on the development of buoyant surface jets are evaluated quantitatively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.919-924
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• 2006

This paper presents active vibration control using a hybrid mount which consists of rubber element and the piezostack actuator. After identifying stiffness and damping properties of the rubber element and piezoelectric elements, a mechanical model of the hybrid mount is established. The mount model is then incorporated with the vibration system, and the governing equation of motion is obtained in a state space. A sliding mode controller and LQG controller are designed in order to actively attenuate the vibration of the system subjected to high frequency and small magnitude excitations. Control responses such as acceleration and force transmission through the hybrid mount are evaluated by computer simulation.

• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.23-27
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• 2006

The power split hybrid powertrain is considered to be one of the most prospective configuration for the hybrid electric vehicle (HEV). Toyota Prius, representing this type of vehicle, showed outstanding performances in fuel efficiency, emission reduction and acceleration. The excellence is largely due to the fact that it utilizes almost all operation modes of HEV. Those modes include ZEV (Zero Emission Vehicle) driving, idle stop, fuel cut-off, power assist, active charging, regenerative braking and so forth. In this paper, a few of the mode operations were simulated using AVL Cruise. Also, control logics to operate the powertrain in each mode were developed. The states of powertrain components were displayed and analyzed. By controlling the three components (engine, motor and generator), it was possible to run the powertrain in several hybrid operation modes.

• Journal of electromagnetic engineering and science
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• v.18 no.4
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• pp.231-241
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• 2018

In this paper, we consider the anti-attack procedure of a ballistic missile defense system (BMDS) at different operating frequencies at its phased-array radar station. The interception performance is measured in terms of lateral divert (LD), which denotes the minimum acceleration amount available in an interceptor to compensate for prediction error for a successful intercept. Dependence of the frequency on estimation accuracy that leads directly to prediction error is taken into account, in terms of angular measurement noises. The estimation extraction is performed by means of an extended Kalman filter (EKF), considering two typical re-entry trajectories of a non-maneuvering ballistic missile (BM). The simulation results show better performance at higher frequency for both tracking and intercepting aspects.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.247-250
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• 2003

In this paper, we propose a robust controller for motion control of n-link robot manipulators using visual feedback. The desired joint velocity and acceleration is obtained by the feature-based visual systems and is used in the joint velocity control loop for trajectory control of the robot manipulator. We design a robust controller that compensates for bounded parametric uncertainties of robot dynamics. The stability analysis of robust joint velocity control system is shown by Lyapunov Method. The effectiveness of the proposed method is shown by simulation results on the 5-link robot manipulators with two degree of freedom.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.322-324
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• 1994

The 2nd prototype LPM is designed as single side stator structure for improving the thrust force and acceleration time. Experimental results are shown that the static and dynamic characteristics are improved compared with the 1 st prototype. By the computer simulation, the permanent magnet design method is also clarified to desired thrust force. And microstep driver is adopted to the position controller to the designed LPM. The driver suppressed position errors within 1/10 pitch.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.10
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• pp.929-934
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• 2014

Reaction force compensation (RFC) mechanism can relieve the vibration of base system caused by acceleration and deceleration of mover. In this paper, we propose a new passive RFC mechanism with a movable additional mass to reduce vibration of the system base as well as displacement of the magnet track. First, equation of motion for the new passive RFC mechanism is derived and simulated to tune design parameters such as masses and spring coefficients. Simulation results show that the vibration of the system base of the stage with the new RFC mechanism.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.91-96
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• 2001

When it is considered that many vehicle rides on the road and ride quality is an important method to evaluate vehicle performance with handling, running-over-bump manoeuvre may be suitable for testing ride quality. In this paper, a computed model has roughly steering system and lumped mass, connected by joint each rigid body, and suspension that has beam elements and has shock absorber as force element to represent nonlinear characteristics. A computer simulations for passing over a bump were made with two velocities. One side of vehicle passed over bump in due consideration of driver's habit that driver is subject to avoid a bad ride quality. On simulation, vertical acceleration, pitch angle and roll angle were measured at the mass center of chassis each case.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1103-1108
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• 2007

This paper describes a robust model-based roll state estimator for application to the detection of impending vehicle rollover. The roll state estimator is based on a 2-D bicycle model and a roll model to estimate the maneuver-induced vehicle roll motion. The measurement signals are lateral acceleration, yaw rate, steering angle, and vehicle speed. Vehicle mass is adapted to obtain robust performance of the estimator. Computer simulation is conducted to evaluate the proposed roll state estimator by using a validated vehicle simulator. It is shown that the roll state estimator shows robust performance without exact vehicle mass information.