• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.498-500
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• 2012

According to the climatic characteristics of the wind power output is difficult to predict and a severe strain due to a change in output has been very influential in the grid. Jeju Hangwon wind farm, many of the wind generator is installed in a wide area because it is not have this device that artificially Smoothing is needed. In addition, By the requirements of the power company active power supply / control and improve power system reliability and energy storage during the peak demand for electricity using the energy stored in the power supply is needed. In this paper, Unit 12 in Jeju Hangwon demonstrated 0.5MW PCS and energy storage system associated with the wind through the stabilization of output and the leveling of output and test results will be introduced.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.21-32
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• 2013

This is a preliminary study for the real-time feedback vibration control of building structures. The study developed a wireless acceleration sensor system based on authentic technology capacities, to integrate with the Prototype AMD system and ultimately construct the feedback vibration control system. These systems were used to evaluate the basic performance levels of the control systems within model building structures. For this purpose, the study first developed a wireless acceleration sensor unit that integrates an MEMS sensor device and bluetooth communication module. Also, the study developed an operating program that enables control output based on real-time acceleration response measurement and control law. Furthermore, the Prototype AMD and motor driver system were constructed to be maneuvered by the AC servo-motor. Eventually, all these compositions were used to evaluate the real-time feedback vibration control system of a 2-story model building, and qualitatively measure the extent of vibrational reduction of the target structure within the laboratory validation tests. As a result of the tests, there was a definite vibrational reduction effect within the laboratory validation tests. As a result of the tests, there was a definite vibrational reduction effect within 1st and 2nd resonance frequency as well as the random frequency of the model building structure. Ultimately, this study confirmed the potential of its wireless acceleration sensor system and AMD system as an effective tool that can be applied to the active vibration control of other structures.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.4
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• pp.188-193
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• 2017

In this paper, a ZVS-PWM high-frequency inverter with a PWM control function is applied to commercial system 220[Vrms], and a resonator type ZVS-PWM high-frequency inverter circuit with a fixed-two methods were proposed. The parameters of the transformer model equivalent circuit of a copier fixing device, which is an essential element in the parameter optimization of the proposed circuit, are obtained by using a high-frequency amplifier and its frequency characteristics are described. The proposed method compared to the existing single-ended ZVS-PFM high frequency inverter can suppress the voltage and current peak value of the power semiconductor switching device and reduce the switching loss. The efficiency of the proposed method itself is 98[%] at rated power output. Also, the efficiency of 96[%] can be obtained even at low output, so that the proposed high frequency inverter is very efficient inverter. The total efficiency from the commercial AC input to the inverter output is 93[%] at rated, which is considered efficient for use in copying machines. In addition, the diode bridge loss accounts for the largest portion of the overall system efficiency distribution. On the other hand, the nonparallel filter has a very low loss.

• Journal of the Ergonomics Society of Korea
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• v.33 no.2
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• pp.109-124
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• 2014

Objective: This study was conducted for one-hand users including hemiplegic clients currently using general folding manual wheelchairs, so as to analyze their specific problems and recommend solutions regarding usage. Background: Traditional manual wheelchairs require considerable use and control of both hands for operation, thus adaptations become necessary for individuals with asymmetrical use of hands. Method: Thirty hemiplegic clients who were admitted to rehabilitation and convalescent hospitals participated as subjects. The research tools were general folding manual wheelchairs commonly used by people with impaired gait, and the Wheelchair Skills Tests (WST) WST-M/WCU 4.1 version was adopted as the assessment tool. All participants were asked to fill out questionnaires on demographics and wheelchair usage characteristics. Assessment procedures were performed with currently used manual wheelchairs and with/without the use of foot to control the wheelchair. Results: When the participants drove folding manual wheelchairs without the use of foot, even the lowest failure rate among the WST items tested recorded 96.7%. On the contrary, with the use of foot in maneuvering the wheelchairs, failure rates dropped noticeably and success rate among the WST items tested was as high as 86.7%. Conclusion: These findings imply that the use of one-arm (hand) propellable (drivable) wheelchair can be an active and effective solution in resolving problems for hemiplegic clients using existing manual wheelchairs. As such, the government should provide institutional support to further develop and distribute this device or technology, and promote relative research in tandem. For now, the supply of commercially available device to hemiplegic clients is deemed urgent and also a mechanism to provide the devices and relevant services. Application: This study offers viable solutions for hemiplegic clients who rely on existing manual wheelchairs to increase their mobility and occupational performance.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.7
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• pp.875-880
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• 2007

Scientific challenges in the field of MR(magnetorheological) fluids and devices consist in the development of MR devices, the mathematical modeling and simulation of MR devices, and the development of (optimal) control algorithm for MR device systems. To take a maximum advantage of MR fluids in control applications a reliable mathematical model, which predicts their nonlinear characteristics, is needed. A inverse model of the MR device is required to calculate current(or voltage) input of MR damper, which generates required damping force. In this paper, we implemented test a bench for shear mode rotary MR damper and laboratory tests were performed to study the characteristics of the prototype shear-mode rotary MR damper. The direct identification and inverse dynamics modeling for shear mode rotary MR dampers using multi-layer neural networks are studied.

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.123-132
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• 2014

In this paper, we study the verification techniques for OS integrity that can be more fatal than applications in case of security issues. The dissemination of smartphones is rapidly progressing and there are many similarities of smartphones and PCs in terms of security risks. Recently, in mobile network environment, there is a trend of increasing damages and now, there are active researches on a system that can comprehensively respond to this. As a way to prevent these risks, integrity checking method on operation system is being researched. As most integrity checking algorithms are classified by verification from the levels before booting the OS and at the time of passing on the control to the OS, in which, there are minor differences in the definitions of integrity checking or its methods. In this paper, we suggests the integrity verification technique of OS using a boot loader and a physically independent storing device in the mobile device.

• Journal of Power Electronics
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• v.5 no.3
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• pp.233-239
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• 2005

In this paper, a new conceptual circuit configuration of a 3-phase voltage source, soft switching AC-DC-AC converter using an IGBT module, which has one ARCPL circuit and one ARDCL circuit, is presented. In actuality, the ARCPL circuit is applied in the 3-phase voltage source rectifier side, and the ARDCL circuit is in the inverter side. And more, each power semiconductor device has a novel clamp snubber circuit, which can save the power semiconductor device from voltage and current across each power device. The proposed soft switching circuits have only two active power semiconductor devices. These ARCPL and ARDCL circuits consist of fewer parts than the conventional soft switching circuit. Furthermore, the proposed 3-phase voltage source soft switching AC-DC-AC power conversion system needs no additional sensor for complete soft switching as compared with the conventional 3-phase voltage source AC-DC-AC power conversion system. In addition to this, these soft switching circuits operate only once in one sampling term. Therefore, the power conversion efficiency of the proposed AC-DC-AC converter system will get higher than a conventional soft switching converter system because of the reduced ARCPL and ARDCL circuit losses. The operation timing and terms for ARDCL and ARCPL circuits are calculated and controlled by the smoothing DC capacitor voltage and the output AC current. Using this control, the loss of the soft switching circuits are reduced owing to reduced resonant inductor current in ARCPL and ARDCL circuits as compared with the conventional controlled soft switching power conversion system. The operating performances of proposed soft switching AC-DC-AC converter treated here are evaluated on the basis of experimental results in a 50kVA setup in this paper. As a result of experiment on the 50kVA system, it was confirmed that the proposed circuit could reduce conduction noise below 10 MHz and improve the conversion efficiency from 88. 5% to 90.5%, when compared with the hard switching circuit.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.180-180
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• 2010

Thin film transistors (TFTs) based on oxide semiconductors have emerged as a promising technology, particularly for active-matrix TFT-based backplanes. Currently, an amorphous oxide semiconductor, such as InGaZnO, has been adopted as the channel layer due to its higher electron mobility. However, accurate and repeatable control of this complex material in mass production is not easy. Therefore, simpler polycrystalline materials, such as ZnO and $SnO_2$, remain possible candidates as the channel layer. Inparticular, ZnO-based TFTs have attracted considerable attention, because of their superior properties that include wide bandgap (3.37eV), transparency, and high field effect mobility when compared with conventional amorphous silicon and polycrystalline silicon TFTs. There are some technical challenges to overcome to achieve manufacturability of ZnO-based TFTs. One of the problems, the stability of ZnO-based TFTs, is as yet unsolved since ZnO-based TFTs usually contain defects in the ZnO channel layer and deep level defects in the channel/dielectric interface that cause problems in device operation. The quality of the interface between the channel and dielectric plays a crucial role in transistor performance, and several insulators have been reported that reduce the number of defects in the channel and the interfacial charge trap defects. Additionally, ZnO TFTs using a high quality interface fabricated by a two step atomic layer deposition (ALD) process showed improvement in device performance In this study, we report the fabrication of high performance ZnO TFTs with a $Si_3N_4$ gate insulator treated using plasma. The interface treatment using electron cyclotron resonance (ECR) $O_2$ plasma improves the interface quality by lowering the interface trap density. This process can be easily adapted for industrial applications because the device structure and fabrication process in this paper are compatible with those of a-Si TFTs.

• Journal of Power Electronics
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• v.17 no.1
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• pp.56-66
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• 2017

Fast and accurate fault detection is the primary step and one of the most important tasks in fault tolerant converters. In this paper, a fast and simple method is proposed to detect and diagnosis the faulty cell in a cascaded H-bridge multilevel inverter under a short circuit fault. In this method, the reference voltage is calculated using switching control pulses and DC-Link voltages. The comparison result of the output voltage and the reference voltage is used in conjunction with active cell pulses to detect the faulty cell. To achieve this goal, the cell which is active when the Fault signal turns to "0" is detected as the faulty cell. Furthermore, consideration of generating the active cell pulses is completely described. Since the main advantage of this method is its simplicity, it can be easily implemented in a programmable digital device. Experimental results obtained with an 11-level inverter prototype confirm the effectiveness of the proposed fault detection technique. In addition, they show that the diagnosis method is unaffected by variations of the modulation index.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.8
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• pp.743-748
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• 2007

Recently, various types of camera mouse are developed using the image processing. The camera mouse showed limited performance compared to the traditional optical mouse in terms of the response time and the usability. These problems are caused by the mismatch between the size of the monitor and that of the active pixel area of the CMOS Image Sensor. To overcome these limitations, we designed a new input device that uses the face recognition as well as the speech recognition simultaneously. In the proposed system, the area of the monitor is partitioned into 'n' zones. The face recognition is performed using the web-camera, so that the mouse pointer follows the movement of the face of the user in a particular zone. The user can switch the zone by speaking the name of the zone. The multimodal mouse is analyzed using the Keystroke Level Model and the initial experiments was performed to evaluate the feasibility and the performance of the proposed system.