• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.4
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• pp.1-10
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• 1997

Resonant dual converters are remarkable as circuit topologies that can realize a power conversion on the high switching frequency with low switching loss. In this paper, bi-directional resonant power conversion system is established, which makes the powering and the regeneration possible, by loading an induction motor. For its practical use, the operation characteristics of the system are to be examined through a series of experiments. The characteristics are : (l)input/output, (2)resonants. (3)tum-off and zero voltage in the main devices and clamp device. By examining the measured waveforms, this study will investigate some problems in the system, and also give some suggestions for a further study.

• Journal of Power Electronics
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• v.17 no.4
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• pp.1117-1126
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• 2017

The main contribution of this paper is the use of sensorless active diodes to generate the gate signals for a three-phase boost-rectifier with a self-powered control scheme. The sensorless operation is achieved making use of the gate control signals generated by the active diode schemes on each of the switching devices using a pulse width half-controlled boost rectifier modulation technique (PWM-HCBR). The proposed scheme synchronizes the gate control signals with a three phase voltage supply. Autonomous operation is obtained making use of the output DC bus to feed the control circuitry, the active diodes and the driver circuitry. The three-phase boost-rectifier is supplied by a three-phase permanent magnet electric generator powered by a solar concentrator dish with variable voltage and variable frequency conditions. Experimental results report an efficiency of up to 94.6% for 25 W and an input of 3.6 V peak per phase with 450.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.24-34
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• 2019

An automotive automatic transmission is a popular power-transmitting device in passenger vehicles, as it provides various speed ratios for diverse driving conditions with easy manipulation and smooth gear shifting. The transmission is mainly composed of input and output shafts, planetary gear sets, brakes/clutches, and housing, and it yields multiple forward gears and one reverse gear by actuating the shifting devices of the brakes and clutches. In developing a new transmission, kinematic configurations of a transmission, which presents a brief structure and actuation schemes for speed ratios, need to be checked to determine if the structure can be assembled in a layout. It is impossible for a transmission concept having any interference in connecting main components to be developed further in the design process, since connection interference leads to failure of a layout design in the 2-D plane. In this research, an analysis of the assemblability of a front-wheel drive automatic transmission is carried out on an example concept design by applying the vertex addition algorithm based on graph theory.

• Current Optics and Photonics
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• v.1 no.1
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• pp.65-72
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• 2017

We propose a nearly lossless, compact, electrically modulated vertical directional coupler, which is based on the controllable evanescent coupling in a previously proposed graphene-assisted total internal reflection (GA-FTIR) scheme. In the proposed device, two single-mode waveguides are separate by graphene-$SiO_2$-graphene layers. By changing the chemical potential of the graphene layers with a gate voltage, the coupling strength between the waveguides, and hence the coupling length of the directional coupler, is controlled. Therefore, for a properly chosen, fixed device length, when an input wave is launched into one of the waveguides, the ratio of their output powers can be controlled electrically. The operation of the proposed device is analyzed, with the dispersion relations calculated using a model of a one-dimensional slab waveguide. The supermodes in the coupled waveguide are calculated using the finite-element method to estimate the coupling length, realistic devices are designed, and their performance was confirmed using the finite-difference time-domain method. The designed $3{\mu}m$ by $1{\mu}m$ device achieves an insertion loss of less than 0.11 dB, and a 24-dB extinction ratio between bar and cross states. The proposed low-loss device could enable integrated modulation of a strong optical signal, without thermal buildup.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.10
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• pp.3750-3770
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• 2021

This study investigates open-source dynamic XSS filters used as security devices in web applications to account for the effectiveness of filters in protecting against XSS attacks. The experiment involves twelve representative filters, which are examined individually by placing them into the final output function of a custom-built single-input-form web application. To assess the effectiveness of the filters in their tasks of sanitizing XSS payloads and in preserving benign payloads, a black-box testing method is applied using an automated XSS testing framework. The result in working with malicious and benign payloads shows an important trade-off in the filters' tasks. Because the filters that only check for dangerous or safe elements, they seem to neglect to validate their values. As some safe values are mistreated as dangerous elements, their benign payload function is lost in the way. For the filters to be more effective, it is suggested that they should be able to validate the respective values of malicious and benign payloads; thus, minimizing the trade-off. This particular assessment of XSS filters provides important insight regarding the filters that can be used to mitigate threats, including the possible configurations to improve them in handling both malicious and benign payloads.

• Current Optics and Photonics
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• v.5 no.4
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• pp.384-390
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• 2021

This paper presents a wide-range tunable wavelength-locking technology based on optoelectronic oscillation (OEO) loops for optical fiber sensors and microwave photonics applications, explains the theoretical fundamentals of the design, and demonstrates a method for locking the relative wavelength differences between a leader semiconductor laser and its follower lasers. The input of the OEO loop in the proposed scheme (the relative wavelength difference) determines the radio-frequency (RF) signal frequency of the oscillation output, which is quantized into an injection current signal for feedback to control the wavelength drift of follower lasers so that they follow the wavelength change of the leader laser. The results from a 10-hour continuous experiment in a field environment show that the wavelength-locking accuracy reached ±0.38 GHz with an Allan deviation of 6.1 pm over 2 hours, and the wavelength jitter between the leader and follower lasers was suppressed within 0.01 nm, even though the test equipment was not isolated from vibrations and the temperature was not controlled. Moreover, the tunable range of wavelength locking was maintained from 10 to 17 nm for nonideal electrical devices with limited bandwidth.

• Journal of Power Electronics
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• v.19 no.3
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• pp.645-654
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• 2019

In this paper, a new high step up DC/DC converter with a modified super-lift technique is presented. The coupled inductor technique is combined with the super-lift technique to provide a tenfold or more voltage gain with a proper duty cycle and a low turn ratio. Due to a high conversion ratio, the voltage stress on the semiconductor devices is reduced. As a result, low voltage ultra-fast recovery diodes and low on resistance MOSFET can be used, which improves the reverse recovery problems and conduction losses. This converter employs a passive clamp circuit to recycle the energy stored in the leakage inductance. The proposed convertor features a high conversion ratio with a low turn ratio, low voltage stress, low reverse recovery losses, omission of the inrush currents of the switch capacitor loops, high efficiency, small volume and reduced cost. This converter is suitable for renewable energy applications. The operational principle and a steady-state analysis of the proposed converter are presented in details. A 200W, 30V input, 380V output laboratory prototype circuit is implemented to confirm the theoretical analysis.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.1-7
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• 2018

As the performance and density of IC (integrated circuit) devices increase, power and signal integrities in the global interconnects of advanced packaging technologies are becoming more difficult. Thus, the global interconnect technologies should be designed to accommodate increased input/output (I/O) counts, improved power grid network integrity, reduced RC delay, and improved electrical crosstalk stability. This requirement resulted in the fine-pitch interconnects with a low-k dielectric in 3D packaging or wafer level packaging structure. This paper reviews an organic-inorganic hybrid material as a potential dielectric candidate for the global interconnects. An organic-inorganic hybrid material called polysiloxane can provide spin process without high temperature curing, an excellent dielectric constant, and good mechanical properties.

• International journal of advanced smart convergence
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• v.11 no.2
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• pp.108-117
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• 2022

The recent development of information and communication technology has a great impact on the audio/video industry. In particular, IP-based AoIP transmission technology and AVB technology are making changes in the audio/video market. Video signal transmission technology has been introduced to the market through a network, but it has not replaced the video switcher function. Video signals in the conference room or classroom are still controlled by the switching device. In order to switch input/output video devices, a cable that is not limited by distance must be connected to the switcher. In addition, the control of the switching device must be performed by a person who has received professional training. In this paper, it is a technology that can be operated even by non-experts by replacing complex video cables (RGB, DVI, HDMI, DP) with LAN cables and enabling IP-based video switching and transmission (Video Mirroring over IP: VMoIP) to replace video switcher equipment. We are going to do this study, I/O videos were controlled in the form of matrix and high-definition videos were transmitted without distortion, and VMoIP is expected to become the standard for video switching systems in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.2
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• pp.353-368
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• 2023

The four wing unmanned aerial vehicle owns the characteristics of small size, light weight, convenient operation and well stability. But it is easily disturbed by external environmental factors during flight with these disadvantages of short endurance and poor attitude solving ability. For solving these problems, a microprocessor based on STM32 chip is designed and the overall development is completed by the resources such as built-in timer and multi-function mode general-purpose input/output provided by the master micro controller unit, together with radio receiver, attitude meter, barometer, electronic speed control and other devices. The unmanned aerial vehicle can be remotely controlled and send radio waves to its corresponding receiver, control the analog level change of its corresponding channel pins. The master control chip can analyze and process the data to send multiple sets pulse signals of pulse width modulation to each electronic speed control. Then the electronic speed control will transform different pulse signals into different sizes of current value to drive the motor located in each direction of the frame to generate different rotational speed and generate lift force. To control the body of the unmanned aerial vehicle, so as to achieve the operator's requirements for attitude control, the PID controller based on Kalman filter is used to achieve quick response time and control accuracy. Test results show that the design is feasible.