• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2006.11a
• /
• pp.60-66
• /
• 2006

This paper presents a new way achieving better welding results of gas mental arc welding (GMAW) system by using a decentralized control method. In this paper, the GMAW system is considered as two separated subsystems such as a power source of GMAW (PS-GMAW) and a wire feed unit (WFU). The mathematical modeling of PS-GMAW and WFU are presented. Based on the modeling of two subsystems, a sliding mode controller and a proportional controller is designed for controlling the PS-GMAW and the WFU, respectively. Two decentralized controllers have to be designed to control the out welding arc of the GMAW to be stable and tracking the setting value accurately during the welding process. Furthermore, the simulation and experimental results are shown to prove the effectiveness of the proposed controllers.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1081-1082
• /
• 2008

Photovoltaic (PV) power generation system has been widely studied as a clean and renewable power source. The purpose of this study is to keep the output power of photovoltaic cells maximum under any weather conditions. There are so many MPPT (Maximum Power Point Tracking) methods. P&O method has been used as a key MPPT method, both voltage and current coming out from PV array have to be feedback in the method. Thus, the system has a complex structure, and may fail to track MPP of PV array when unexpected weather conditions happen. In order to reduce the feedback components, POS MPPT control method was proposed by the authors. In this paper, the authors apply the POS MPPT control method to three phase PCS system. And the effectiveness of the proposed control scheme is demonstrated through PSCAD/EMTDC simulation.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2008.05a
• /
• pp.407-410
• /
• 2008

This paper presents a maximum power point tracking(MPPT) of photovoltaic system with duty ratio of DC-DC converter considered load. A variation of solar irradiation is most important factor in the MPPT of PV system That is nonlinear, aperiodic and complicated. NN was widely used due to easily solving a complex math problem. The paper consists of solar radiation source, DC-DC converter, DC motor and load(cf, pump). NN algorithm apply to DC-DC converter through an adaptive control of neural network, calculates converter-duty ratio using an adaptive control of NN. The results of an adaptive control of NN compared with the results of converter-duty ratio which are calculated mathematical modeling and evaluate the proposed algorithm. The experimental data show that an adequacy of the algorithm was established through the compared data.

• The Journal of the Korea Contents Association
• /
• v.13 no.1
• /
• pp.55-63
• /
• 2013

NUI(Natural User Interfaces) has been developed through CLI(Command Line Interfaces) and GUI(Graphical User Interfaces). NUI uses many different input modalities, including multi-touch, motion tracking, voice and stylus. In order to adopt NUI to legacy GUI applications, he/she must add device libraries, modify relevant source code and debug it. In this paper, we propose a gesture-based interface model that can be applied without modification of the existing event-based GUI applications and also present the XML schema for the specification of the model proposed. This paper shows a method of using the proposed model through a prototype.

• Journal of Welding and Joining
• /
• v.8 no.3
• /
• pp.60-69
• /
• 1990

Plasma arc cutting is a fusion cutting process in which a gas-constricted arc is employed to produce a high-temperature, high-velocity plasma jet on the workpiece. This process provides some advantages such as increased cutting velocity, excellent working accuracy and the ability to cut special materials (widely used stainless steels and Al-alloys, for example), when compared with iconventional oxyfuel gas cutting. From the view point of price and reliability of the power source, plasma arc cutting has also some distinct advantages over laser beam cutting. High-speed machines with NC or CNC systems are needed for the plasma arc or laser beam cutting process, while for oxyfuel gas cutting, low-speed machines with copying templates or optical-shape tracking sensors can be applied. The low price and high flexibility of the microprocessor arc contributing more and more the application of CNC system in the plasma arc cutting process, as in other manufacturing fields. From these points of view, a microprocessor-based plasma arc cutting system was developed by using a reference-pulse system, and its performance was tested. The interpolating routines were programmed in the assembly language for saving the memory volume and improving the compouting speed, which has an intimate relationship with the available cutting velocity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.18 no.12
• /
• pp.1352-1358
• /
• 2007

This paper address the statistical charateristics of MUSIC algorithm which is suggested as satellite direction finding algorithm. If the MUSIC algorithm is adopted as a satellite direction detection method in mobile TT&C system, then the statistical performance of the MUSIC algorithm will be closely related with the overall performance of the system. So statistical characteristics of the parameter in the respect of SNR and data length are addressed and then analyse the final effects to the satellite direction finding.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.994-995
• /
• 2006

This paper presents a grid-connected photovoltaic (PV) system with direct coupled power quality control (PQC) algorithm, which uses an inner current control loop (PRT : polarized ramp time) and outer feedback control loop to improve grid power quality and maximum power point tracking (MPPT) of PV arrays. To reduce the complexity, cost and number of power conversions, which results in higher efficiency, single stage CCVSI (Current Controlled Voltage Source Inverter) is used. The proposed system operation has been divided into two modes (sunny and night). In night mode, the proposed system operates to compensate the reactive power demanded by nonlinear or variation in loads. in sunny mode, the proposed system performs PQC to reduce harmonic current and improve power factor as well as MPPT to supply active power from the PV arrays simultaneously. it is shown that the proposed system improves the system utilization factor to 100% which is generally low for PV system (20%). To verify the proposed system, a comprehensive evaluation with theoretical analysis and simulation results are presented.

• Journal of Power Electronics
• /
• v.3 no.1
• /
• pp.62-67
• /
• 2003

Recently, photovoltaic system has been studied widely as a renewable energy system, because it does not produce environmental pollution and it has infinity energy source from the sun. A study on photovoltaic system has a lot of problems like as reappearance and repetition of some situation in the laboratory experiment for development of MPPT algorithm and islanding detection algorithm. because output characteristics of solar cell are varied by irradiation and surface temperature of solar cell. Therefore, the assistant equipment which emulates the solar cell characteristics which can be controlled arbitrarily by researcher is require to the researchers for reliable experimental data. In this paper, the virtual implement of solar cell (VISC) system is proposed to solve these problems and to achieve reliable experimental result on photovoltaic system. VISC system emulates the solar cell output characteristics, and this system can substitute solar cell in laboratory experiment system. To realize the VISC, mathematical model of solar cell is studied for driving converter and the DC/DC converters are compared in viewpoint of tracking error using computer simulation. Output dynamic characteristic of PV array is varied by irradiation and PWM converter performance is studied using PSIM simulator.

• Journal of the Ergonomics Society of Korea
• /
• v.27 no.3
• /
• pp.43-52
• /
• 2008

Human errors are now considered as the most significant source of accidents or incidents in large-scale systems such as aircraft, vessels, railway, and nuclear power plants. As 61% of the train accidents in Korea railway involving collisions, derailments and fires were caused by human errors, there is a strong need for a systematic research that can help to prevent human errors. Although domestic railway operating companies use a variety of methods for analyzing human errors, there is much room for improvement. Especially, because most of them are based on written papers, there is a definite need for a well-developed computerized system supporting human error analyzing tasks. The purpose of this study is to propose a framework for a computerized human error analysis system focused on the railway industry on the basis of human error analysis mechanism. The proposed framework consists of human error analysis (HEA) module, similar accident tracking (SAT) module, cause factor recommendation (CFR) module, cause factor management (CFM) module, and statistics (ST) module.

• Journal of IKEEE
• /
• v.19 no.2
• /
• pp.210-218
• /
• 2015

In this paper an auto-switching energy harvesting circuit using vibration and thermoelectric energy is proposed. Since the maximum power point of a thermoelectric generator(TEG) output and a vibration device(PEG) output is 1/2 of their open-circuit voltage, an identical MPPT controller can be used for both energy sources. The proposed circuit monitors the outputs of the TEG and PEG, and chooses the energy source generating a higher output voltage using an auto-switching controller, and then harvests the maximum power from the selected device using the MPPT controller. The proposed circuit is designed in a $0.35{\mu}m$ CMOS process and its functionality has been verified through extensive simulations. The designed chip occupies $1.4mm{\times}1.2mm$ including pads.