• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2003.10a
• /
• pp.491-494
• /
• 2003

An Automatic Water Level Measurement System has been developed in this study. It has the characteristics that it use lower power and solar power and it has the ability of sending data and remote-controlled by wireless MODEM this system was set up in the experimental site and was tested. Also, the management system for the water level data has been developed and will be used by instruments administrating reservoirs.

• ETRI Journal
• /
• v.31 no.2
• /
• pp.243-245
• /
• 2009

A novel ultra-low-power readout circuit for a pH-sensitive ion-sensitive field-effect transistor (ISFET) is proposed. It uses an ISFET/reference FET (REFET) differential pair operating in weak-inversion and a simple current-mode metal-oxide semiconductor FET (MOSFET) translinear circuit. Simulation results verify that the circuit operates with excellent common-mode rejection ability and good linearity for a single pH range from 4 to 10, while only 4 nA is drawn from a single 1 V supply voltage.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.4
• /
• pp.1586-1592
• /
• 2017

Voltage sourced converter (VSC) based direct-current (DC) grid has the ability to control power flow flexibly and securely, thus it has become one of the most valid approaches in aspect of large-scale renewable power generation, oceanic island power supply and new urban grid construction. To solve the optimal power flow (OPF) problem in DC grid, an adaptive particle swarm optimization (PSO) algorithm based on fuzzy control theory is proposed in this paper, and the optimal operation considering both power loss and voltage quality is realized. Firstly, the fuzzy membership curve is used to transform two objectives into one, the fitness value of latest step is introduced as input of fuzzy controller to adjust the controlling parameters of PSO dynamically. The proposed strategy was applied in solving the power flow issue in six terminals DC grid model, and corresponding results are presented to verify the effectiveness and feasibility of proposed algorithm.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.5B no.4
• /
• pp.374-381
• /
• 2005

The ability to provide quality power has become a significant issue in power systems. The main causes of poor power quality are harmonic currents, poor power factor, supply-voltage variations, etc. A technique of achieving both active current distortion compensation, power factor correction and also mitigating the supply-voltage variation (sag or swell) at the load side is presented in this paper. The operation and rating issues of the proposed Single-phase Unified Power Quality Conditioner are also highlighted. To reduce the total cost while simultaneously increasing the performance, the system is fully digitally controlled using the fixed-point TMS320F240 digital signal processor. The performances of the UPQC, which is composed by shunt and series PWM controlled-converters, have been verified on a laboratory prototype.

• Journal of Power Electronics
• /
• v.15 no.4
• /
• pp.987-993
• /
• 2015

Wireless power transfer technologies typically include inductive coupling, magnetic resonance, and capacitive coupling methods. Among these methods, capacitive coupling wireless power transfer (CCWPT) has been studied to overcome the drawbacks of other approaches. CCWPT has many advantages such as having a simple structure, low standing power loss, reduced electromagnetic interference (EMI) and the ability to transfer power through metal barriers. In this paper, the CCWPT system with 6.78MHz class D inverter is proposed and analyzed. The proposed system consists of a 6.78MHz class D inverter with a LC low pass filter, capacitor between a transmitter and a receiver, and impedance transformers. The system is verified with a prototype for charging mobile devices.

• Journal of Power Electronics
• /
• v.8 no.3
• /
• pp.268-274
• /
• 2008

This paper presents a proposed position controller for a vector controlled induction motor. The position controller design depends on the rotational motion equations and a classical speed controller (CSC) performance. The CSC is designed to have the ability to track variable reference inputs and to provide a predefined system performance. Standard position controller in industry is presented to analyze its performance and its drawbacks. Then the proposed position controller is designed, based on the well defined rotational motion equations. The proposed position controller and the CSC are applied to control the position and speed of the vector controlled induction motor with different ratings. Simulation results at different operating conditions are presented to evaluate the proposed controllers' performance. The results show that the CSC can drive the motor with a predefined speed performance and can track a variable reference speed with an approximately zero steady state error. The results also show that the proposed position controller has the ability to effect high-precision positioning in a limited time and to track a variable reference position with a zero steady state error.

• Journal of Korea Technology Innovation Society
• /
• v.8 no.1
• /
• pp.277-295
• /
• 2005

The objective of the study is to verify the discriminatory power of valuation indexes in predicting IT small and medium sized manufacturing firms' going concern or firms' failure. The result of the study is expected to be useful in loan evaluation, investment decision, internal management decision making and business improvement. The results of study is as follows. First, we find that at least six valuation index elements are significant ex-ante variable which are discriminating between firms' going concern and firms' failure in IT small and medium sized manufacturing firms in various analysis' results. Second, these index elements are composed of 2 indexes-the ability of technology R&D, the efficient strategy of market penetration and six index elements explain 46% of the total variance. This explainable power of these indexed is similar to that of the existing 16 index elements. Finally, we find that the most important success factor of IT small and medium sized manufacturing firms are the ability of technology R&D and the efficient strategy of market penetration.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2007.05a
• /
• pp.421-423
• /
• 2007

The paper used to the Neral Netwok for a forecasting conservation system A neural network is a powerful data modeling tool that is able to capture and represent complex input/output relationships. The motivation for the development of neural network technology stemmed from the desire to develop an artificial system that could perform "intelligent" tasks similar to those performed by the human brain. The true power and advantage of neural network lies in their ability to represent both linear and non-linear relationships and in their ability to learn these relationships directly from the data being modeled. Form results of this study, the Neral Netwok is will play an important role for insulation diagnosis system of real site GIS and power equipment using $SF_6$ gas.

• Journal of Power System Engineering
• /
• v.19 no.3
• /
• pp.48-54
• /
• 2015

This paper introduced a design method of soldering station that can control two types of soldering iron heater. At design time, to distinguish two types of soldering iron heater the voltage divider rule has been applied, and the distinguished resistor is inserted to handler of soldering iron to prevent misuse by users. And an algorithm to design a PID controllers is proposed. The proposed controllers parameter which can be easily realized, and are designed by using the input output data from systems, and have outstanding ability making the output response of nonlinear systems similar to the desired one. Temperature control experiments were performed to verify the ability of the suggested controller. As a result, suggested PID controller followed the desired ones, and one soldering station can control the various type of soldering irons in real time.

• Proceedings of the KIEE Conference
• /
• 2006.04a
• /
• pp.168-170
• /
• 2006

In this paper, authors realize water AMR(Automatic Meter Reading) network using low power ZigBee protocol included routing ability for improving wireless communitation error detection and network range. ZigBee wireless standard is an important standard of the field related Ubiquitous industry and recently has application to Home-Network. It's special features are to spend low power and to include routing ability each terminator. Because of these features, authors realize water AMR system on Embedded system using ZigBee protocol for applying to transfer data between a water meter and RF module equipped with a water meter in each house.