• Journal of Power Electronics
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• v.16 no.6
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• pp.2327-2337
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• 2016

The mode-switching control of transient process is important to grid-connected 400 Hz solid-state power supply systems. Therefore, this paper analyzes the principle of on-grid and islanding operation of the system with or without local loads in the grid-connected process and provides a theoretical study of the effect of different switching sequences on the mode-switching transient process. The conclusion is that the mode switch (MS) must be turned on before the solid-state switch (STS) in the on-grid process and that STS must be turned off before the MS in the off-grid process. A strategy of mode-switching smooth control for transient process of the system is proposed, including its concrete steps. The strategy utilizes the average distribution of peak currents and the smooth adjustment of peak currents and phases to achieve a no-shock grid connection. The simulation and experimental results show that the theoretical analysis is correct and that the method is effective.

• Journal of Digital Convergence
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• v.9 no.3
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• pp.191-202
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• 2011

Public agencies and local governments have been installing CCTV cameras for the prevention of crime, traffic jam, and unauthorized waste. Additionally, national government agencies and schools, a special corporation by special law, local construction and industrial company installed CCTV cameras of their own and are operating them. Various types of CCTV systems disclosed technical heterogeneity. In February, 2011, Ministry of Public Administration and Security presented guidelines for building an integrated control center. This study examines the case of Busan by using the administrative guidelines. Busan integrated CCTV control center among themselves, police agency and fire department. This study looks into the potential problems with the integration process of CCTV cameras and proposes a solution to them.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1614-1622
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• 2014

A novel equivalent flux sliding-mode observer (SMO) is proposed for dual three-phase interior permanent magnet synchronous motor (DT-IPMSM) drive system in this paper. The DT-IPMSM has two sets of Y-connected stator three-phase windings spatially shifted by 30 electrical degrees. In this method, the sensorless drive system employs a flux SMO with soft phase-locked loop method for rotor speed and position estimation, not only are low-pass filter and phase compensation module eliminated, but also estimation accuracy is improved. Meanwhile, to get the regulator parameters of current control, the inner current loop is realized using a decoupling and diagonal internal model control algorithm. Experiment results of 2MW-level DT-IPMSM drives system show that the proposed method has good dynamic and static performances.

• Journal of Power Electronics
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• v.15 no.2
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• pp.378-388
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• 2015

This paper proposes a pulse width modulation (PWM)-based sliding mode controller (SMC) for a full-bridge DC-DC converter that can eliminate static output voltage error. Hysteretic SMC in DC-DC converter does not have a fixed switching frequency, and applying hysteretic SMC to full-bridge converters is difficult. Fixed-frequency SMC, which is also called PWM-based SMC, based on equivalent control overcomes these shortcomings. However, the controller order reduction in equivalent control in PWM-based SMC causes static output voltage error. To resolve this issue, an integral item is added to the PWM-based SMC. Sliding mode coefficients are designed by applying a standard second-order system to the sliding mode surface. The effect of adding an integral item on the controller is analyzed, and an integral coefficient design method is proposed. Experiment results on a three-level full-bridge DC-DC converter verify the control scheme and design method proposed in this paper.

• Journal of Korean Critical Care Nursing
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• v.14 no.1
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• pp.50-62
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• 2021

Purpose : This study examined the effects of an integrated management program on physical function, cognitive function, and depression in patients with subacute stroke. Methods : A nonequivalent control group design was adopted. The participants were assigned to either the experimental group (n=20) or control group (n=23). The experimental group received an 8-week integrated management program and standard rehabilitation service (i.e., physical therapy and occupational therapy), while the control group received the standard rehabilitation service only. Physical function was measured as gait speed and balance ability using the Berg Balance Scale (BBS). Cognitive function was measured with neuro-behavioral cognitive status examination (NCSE), and depression was measured using the Beck Depression Inventory-II (BDI-II). Repeated measure ANOVA was used to determine changes in physical function, cognitive function, and depression over 8-weeks. Results : The interaction between group and time was significant, indicating that the experimental group showed improvement in gait speed, balance ability, cognitive function (linguistic ability, linguistic memory, reasoning), and a decrease in depression compared to the control group. Conclusion : These results indicate that the integrated management program developed herein was beneficial in restoring physical function, cognitive function, and depression in subacute stroke patients.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.367-371
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• 2004

This paper describes development of automatic flight control system for an unmanned target drone which is operated by Korean army as for anti-air gun shooting training. Current target drone is operated by pilot control of on-board servo motor via remote control system. Automatic flight control system for the target drone greatly reduces work load of ground pilot and can increase application area of the drone. Most UAVs being operated now days use high-priced sensors as AHRS and IMU to measure the attitude, but those are costly. This paper introduces the development of low-cost automatic flight control system with low-cost sensors. The integrated automatic flight control system has been developed by integrating combining power module, switching module, monitoring module and RC receiver as an one module. The performance of automatic flight control system is verified by flight test.

• Journal of Korean Society on Water Environment
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• v.34 no.3
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• pp.339-345
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• 2018

The integrated environmental permit system is currently in operation online. It carries out various functions of postmanagement such as the submission of annual reports containing operations management data onto integrated management workplaces, the operation and management of emission facilities and prevention facilities, and the disclosure of information on the integrated permission. On the other hand, the integrated environmental permit system needs to perform various roles in order to stably manage and smoothly perform the permitting work. It is necessary to utilize this system to establish policies by using diverse operations management data onto integrated management workplaces collected in the integrated environmental permit system. This system can also play a role in improving the post-management system and user convenience after the permission review and approval processes. The integrated environmental permit system can be effectively used to set up the BAT-AEL because it collects all of the cross-media data and identifies the overall status of the workplace. In order to establish a post management system after the approval, it is necessary to provide performance management and performance evaluation functions as conditions of the permit after approval. In addition, a variety of support functions should be provided to enable the permission authority and the environmental expert examination agency to facilitate the review of permits. It will be necessary to provide an evaluation system and a proactive diagnostic function to determine whether permission conditions and permit emission standards will change in the future. Also, it is important to adopt an information exchange platform that can be used to collect the status data onto the workplaces; the platform can also be used as an information exchange site for technical working groups (TWG), and for collecting field experts' opinions.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.95_96
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• 2009

In this paper, a new algorithm of Integrated Volt/Var Control (IVVC) is proposed using Volt/Var control for the Distribution Automation System (DAS) based on the modeling of the distributed load and the distributed current. In the proposed, the load flow based on the modeling of the distributed load with Distributed Generation and the distributed current are estimated from constants of four terminals using the measurement of the current and power factor from a Feeder Remote Terminal Unit (FRTU). For Integrated Volt/Var Control (IVVC), the gradient method is applied to find optimal solution for tap and capacity control of OLTC (On-Load Tap Changers), SVR (Step Voltage Regulator), and SC (Shunt Condenser). What is more Volt/Var control method is proposed using moving the tie switch as well as IVVC algorithm using power utility control. In the case studies, the estimation and simulation network have been testified in Matlab Simulink.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.4
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• pp.688-696
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• 2017

This paper presents an integrated roll-pitch-yaw autopilot using an equivalent based sliding mode control for skid-to-turn nonlinear time-varying missile system with lumped disturbances in its six-equations of motion. The considered missile model are developed to integrate the model uncertainties, external disturbances, and parameters perturbation as lumped disturbances. Moreover, it considers the coupling effect between channels, the variation of missile velocity and parameters, and the aerodynamics nonlinearity. The presented approach is employed to achieve a good tracking performance with robustness in all missile channels simultaneously during the entire flight envelope without demand of accurate modeling or output derivative to avoid the noise existence in the real missile system. The proposed autopilot consisting of a two-loop structure, controls pitch and yaw accelerations, and stabilizes the roll angle simultaneously. The Closed loop stability is studied. Numerical simulation is provided to evaluate performance of the suggested autopilot and to compare it with an existing autopilot in the literature concerning the robustness against the lumped disturbances, and the aforesaid considerations. Finally, the proposed autopilot is integrated in a six degree of freedom flight simulation model to evaluate it with several target scenarios, and the results are shown.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.413-417
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• 1997

Distributed piezoelectric sensor and actuator have been designed for efficient vibration control of a cantilevered beam. Both PZT and PVDF are used in this study, the former as an actuator and the latter as a sensor for our integrated structure. For the PZT actuator, the position and size have been optimized. Optimal electrode shape of the PVDF sensor has been determined. For multi-mode vibration control, we have used two PZT actuators and a PVDF sensor. Electrode shading of PVDF is more powerful for modal force adjustment than the sizing and positioning of PZT. Finite element method is used to model the structure that includes the PZT actuator and the PVDF sensor. By deciding on or off of each PZT segment, the length and the location of the PZT actuator are optimize. Considering both of the host structure and the optimized actuators, it is designed that the active electrode width of PVDF sensor along the span of the beam. Actuator design is based on the criterion of minimizing the system energy in the control modes under a given initial condition. Sensor is designed to minimize the observation spill-over. Modal control forces for the residual(uncontrolled) modes have been minimized during the sensor design. Genetic algorithm, which is suitable for this kind of discrete problems, has been utilized for optimization. Discrete LQG control law has been applied to the integrated structure for real time vibration control. Performance of the sensor, the actuator, and the integrated smart structure has been demonstrated by experiments.