• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.04a
• /
• pp.383-387
• /
• 1996

This paper presents a steering control strategy applicable to vehicle path following problems. This control strategy is based on realistic nonlinear equations of motion of multibody systems described in terms of relative joint coordinates. The acceleration of the steering angle is selected as a control input of the system. This input is obtained by considering position and slope errors at current and at advance times. This steering control strategy is tested in circular and lane change maneuvers with a nonlinear vehicle model.

• Journal of the Korean Society for Precision Engineering
• /
• v.32 no.6
• /
• pp.553-562
• /
• 2015

This paper presents a strategy and an algorithm for levitation control of an over-actuated passive maglev tray system. The passive maglev tray system has more actuators than its degrees of freedom. The actuators of the system are switching when the tray travels longitudinally. Furthermore, the levitation forces of the actuators are non-homogeneous because the actuation devices are not in the moving platform. These characteristics make a limit in using conventional control approaches for levitation. For smooth actuator switching, the actuator force generation should be dependent on longitudinal positions of the tray. To enable constant pose tracking, this research introduces a control strategy and a control algorithm based on integral controllers on virtual variables. The states of the tray are estimated using a Kalman filter and fed to the proposed controller. The performances of the proposed control strategy and the algorithm are validated through tests.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.21 no.3
• /
• pp.238-248
• /
• 2016

In this study, an automatic command mode transition strategy of direct power control (DPC) is proposed for permanent magnet synchronous generators (PMSGs) medium-voltage (MV) offshore wind turbines (WTs). Benchmarking against the control methods are performed based on a three-level neutral-point-clamped (NPC) back-to-back type voltage source converter (VSC). The ramping rate criterion of complex power is utilized to select the switching vector in DPC for a three-level NPC converter. With a grid command and an MPPT mode transition strategy, the proposed control method automatically controls the generated output power to satisfy a grid requirement from the hierarchical wind farm controller. The automatic command mode transition strategy of DPC is confirmed through PLECS simulations based on Matlab. The simulation result of the automatic mode transition strategy shows that the proposed control method of VOC and DPC achieves a much shorter transient time of generated output power than the conventional control methods of MPPT and VOC under a step response. The proposed control method helps provide a good dynamic performance for PMSGs MV offshore WTs, thereby generating high quality output power.

• Journal of Power Electronics
• /
• v.18 no.3
• /
• pp.802-816
• /
• 2018

A digital direct phase-shift control (DDPSC) method based on the phase-shifted full-bridge LLC (PSFB-LLC) converter is presented. This work combines DDPSC with the conventional linear control to obtain a hybrid control strategy that has the advantages of linear control and DDPSC control. The strategy is easy to realize and has good dynamic responses. The PSFB-LLC circuit structure is simple and works in the fixed frequency mode, which is beneficial to magnetic component design; it can realize the ZVS of the switch and the ZCS of the rectifier diode in a wide load range. In this work, the PSFB-LLC converter resonator is analyzed in detail, and the concrete realization scheme of the hybrid control strategy is provided by analyzing the state-plane trajectory and the time-domain model. Finally, a 3 kW prototype is developed, and the feasibility and effectiveness of the DDPSC controller and the hybrid strategy are verified by experimental results.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.23 no.6
• /
• pp.623-632
• /
• 2015

This study proposes a control strategy of the common rail pressure with a fuel injection limitation algorithm to reduce particulate matter (PM) emissions under transient states. The proposed control strategy consists of two parts: injection quantity limitation and rail pressure adaptation. The injection limitation algorithm determines the maximum allowable fuel injection quantity to avoid rich combustion under transient states. The fuel injection quantity is limited by predicting the burned gas rate after combustion; however, the reduced injection quantity leads to deterioration of engine torque. The common rail pressure adaptation strategy is designed to compensate for the reduced engine torque. An increase of the rail pressure under transient states contributes to enhancement of the engine torque as well as reduction of PM emissions by promoting atomization of the injected fuel. The proposed control strategy is validated through engine experiments. The rail pressure adaptation reduced the PM emission by 5-10% and enhanced the engine torque up to 2.5%.

• Journal of Korean Society of Transportation
• /
• v.26 no.5
• /
• pp.63-72
• /
• 2008

Signalized intersections are operated without a signal preemption control strategy in Korea, thus there is no priority treatment for an emergency vehicle passing through the intersections. In this paper, a signal preemption control strategy is introduced to improve the safety and operational efficiency of an emergency vehicle. Using the micro simulation tool, the effects on delay and travel speed of the signal preemption control strategy are analyzed for various traffic conditions to identify the general performance trends. Then, another simulation analysis is performed to verify the feasibility of the control strategy using real network data collected from field study. Results show that the preemption control strategy provides the positive impact on emergency vehicles' operation, but the positive impact is reduced as the v/c ratios increase. As expected, the average delays of the normal vehicles are slightly increased, but the magnitude is not significant. Therefore, it is expected that the introduction of the preemption control strategy in Korea would produce the positive social benefits.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.3
• /
• pp.847-858
• /
• 2015

Control strategy and corresponding parameters have significant impacts on the overall technical and economic characteristics of composite energy storage systems (CESS). A better control strategy and optimized control parameters can be used to improve the economic and technical characteristics of CESS, and determine the maximum power and stored energy capacity of CESS. A novel coordinated control strategy is proposed considering the coordination of various energy storage systems in CESS. To describe the degree of coordination, a new index, i.e. state of charge coordinated response margin of supercapacitor energy storage system, is presented. Based on the proposed control strategy and index, an optimization model was formulated to minimize the total equivalent cost in a given period for two purposes. The one is to obtain optimal control parameters of an existing CESS, and the other is to obtain the integrated optimal results of control parameters, maximum power and stored energy capacity for CESS in a given period. Case studies indicate that the developed index, control strategy and optimization model can be extensively applied to optimize the economic and technical characteristics of CESS. In addition, impacts of control parameters are discussed in detail.

• Journal of the Korean Home Economics Association
• /
• v.43 no.12 s.214
• /
• pp.113-123
• /
• 2005

The purpose of this study was to explore the relationships between patterns of children's requestive strategies, mother's child rearing attitude, and verbal control style. Subjects consisted of 60 5-year-old children and their mothers at preschool in Seoul. The children's requesting behavior were observed during self-selected activities in preschool. A sample of mothers of children completed the questionnaire. The result showed that the children in this study were likely to use more frequent directives of requestive strategies. Boys tended to use more indirect requestive strategies, especially demand with requestive tag. Mothers were likely to use position-oriented verbal control. Warmth and self-control of parenting and person-oriented verbal control were positively related to indirect requestive strategy of children. Rejective and controlling parenting were negatively associated with indirect requestive strategy. Position-oriented verbal control was positively related to direct requestive strategy of children.

• Proceedings of the KIEE Conference
• /
• 1996.07a
• /
• pp.336-338
• /
• 1996

In this paper, a simple control strategy to interconnect the utility line system for three-phase inverter. Conventionally, such interconnection is based on the 3-phase time-domain waveform analysis, though the control based on the plane defined by the two-axis theory is common in the area of the motor control. The new instantaneous power control strategy is introduced, which is based on the d-q axis theory. Simulation results show that proposed control method has good controllability with simple strategy.

• 한국생물공학회:학술대회논문집
• /
• 2001.11a
• /
• pp.333-335
• /
• 2001

A simple control strategy of DO-stat was introduced to the recombinant rGuamerin production process in Pichia pastoris. This induction strategy consisted of two interrelated control loops ‘by which oxygen ratio of inlet gas and methanol feeding rate was controlled. Using this control strategy, over-feeding or under-feeding of methanol could be avoided in concomitance with the efficient control of dissolved oxygen level. As a result, the cell concentration reached 130 g/L and rGuamerin expression level was 450 iu/L, which was more than 40% increased result comparing with the fed-batch process using manual control of methanol feeding rate.