Ho-Bin Song

A Study on the Improved Stability of Inverter through History Management of Semiconductor Elements for Power Supply

This study suggested the methods to check a proper replacement time, etc. by managing operation data of IGBT used as switching element of inverter for improving the stability of inverter, which was checked through practical experiment. This study accumulated and recorded data such as operation time of IGBT and temperature of radiator for the use in setting, etc. of proper replacement time by checking the data through an indicator. Methods and systems suggested in this study will be also easily used in various sectors using other electric system and semiconductor switching elements for power.

A Study on Direct Vector Control System for Induction Motor Speed Control

In this thesis, in order to improve driving characteristics of vector control of an induction motor that is used in motors and elevators, a highly-precise method for flux observation has been exercised by using an algorism of flux observer based on the combined voltage and current model. And it also emphasizes the improvement of the control characteristics in low speed region where established schemes have many problems. The overall system consisted of speed controller with the Anti-windup PI controller, current controller, flux controller. And 2DOF is applied to induction motor in order to supply these weak points of PI speed control method in this paper. To prove the propriety of this paper, the various simulations carried out adequacy and stability using Matlab, and at the same time real system is made, so it is proved. As the results of embodying the system, the robust system is realized.

Comparative Analysis of PI Controller and Disturbance Cancellation Observer of a Feedforward

Abstract This paper designed a robust control of an induction motor using a disturbance cancellation observer of a feedforward control. The speed response of conventional PI controller characteristic is affected by variations of load torque disturbance. In the proposed system, the speed control characteristic used a feedforward control which does not undergo the influence of the load torque disturbance. High speed calculation and processing for vector control is carried out by TMS320C31 digital signal processor. Validity of the proposed control method is verified through simulation and experimental result.Key Words : Feedforward control, Disturbance cancellation observer, PI control * 교신저자 : 김영춘(yckim59@kongju.ac.kr)접수일 09년 11월 01일 수정일 09년 12월 03일 게재확정일 09년 12월 16일 1. 서론 유도전동기의 제어에 일반적으로 사용되고 있는 비례적분 제어기의 경우 구현이 쉽고 간단하며 제어기 이득을 적절히 조절함으로써 최적의 운전상태를 얻을 수 있다. 그러나 비례적분 제어는 이득값을 설정하기가 어렵고, 부하외란이나 파라미터 변동에 매우 민감하기 때문에 운전범위에 제한을 받는다 . 또한, 비례적분 제어는 출력 측에 외란의 영향이 나타나고, 이 외란을 보상하는 시간이 많이 걸리게 된다.[1]외란이 유입되거나 부하토크가 가변 될 경우에는 비례적분 제어기만으로는 안정된 동작 특성을 얻는 것이 힘들게 되어 부가적인 제어기가 필요하게 된다. 이에 본 논문에서는 부하토크를 외란 요소로 간주하여 부하토크 가변 시에도 양호한 동작 특성을 얻고자 한다 . 최소차원 관측기를 이용하여 부하토크를 추정하고, 추정된 부하토크를 feedforward 루프를 통해 상쇄시켜주는 외란상쇄 제어기를 구성하여 외란변동 등의 상황에서도 보다 안정적인 동작을 할 수 있도록 하였다.[2][3] 제안한 이론의 타당성을 입증하기 위하여 시뮬레이션과 실험을 수행하여 확인하였다 시뮬레이션은 Matlab을 이용하여 수행하였으며, 시스템의 응답특성을 알아보기 위하여 시스템 전달함수를 이용하여 구현하였고, 부하토크의 가변에 대해서 PI제어기 시스템과 외란상쇄 관측기 시스템을 비교 시뮬레이션 하였다.[4]시뮬레이션에서 얻어진 데이터를 바탕으로 동일한 조

Characteristics Analysis and Library Development for Common Lamps by Using PSPICE Modeling

Recently, common lamps have been used in a variety of fields, including simple illumination science, and their domain of use is increasingly widening. In this study, we configure a library through modeling and verify its accuracy through simulations for widely used and representative lamps such as CCFL, fluorescent lamps, and HID lamps. On the basis of our experiments, we also perform a lamp simulation using PSPICE, which allows us to take advantage of the lamp library easily.

Method and System for Measuring the Performance Based on the WIFI in Smart Media

The study developed a Wi-Fi performance measurement (measurement of download and upload speeds, delay time, and the Web page loading speed) system and measurement software for smart phones. The measuring of Wi-Fi performance in smart phones is important not only upload and download speeds, but also a loading speed of Web pages for end users; hence, the study included a method for measuring a Web page loading speed as well as its procedures. We expect the study result will provide detailed criteria for quality management, e.g. a quality index and criteria about the Wi-Fi service on the smart phone platform in order to be utilized as an objective standard for service development of operators, and service quality in operation and user environment. In addition, the study will be able to organize a fair, objective, and quality-improved environment by building trustworthy quality measurement S/W and systems, including quality-related policy support and conditions, such as smart phone-based SLA (Service Level Agreement).

The Study on the Integrated Emergency Management System using Network GR-type Receiver and Control Desk

The buildings of domestic wear the upper floors and an underground in-depth reconciliation tendency to do and the possibility of fire occurrence at the time of formation accident is coming to be high. Therefore will be scattered to various place and is established and prevention of disaster information of the receiver which will integrate there is a necessity which will manage. In this paper away where each receiver is installed in the fire for the remote monitoring and controld able to connect to the Internet and fiber optic cable that can be networked fire receiver and control desk was constructed. Between each device can be used by the fire, and more depending on the status of monitoring and alarm, control and maintenance can be performed to develop an integrated management system. The system is evaluated by the criteria of the KFI, and for each segment of the signal propagation time to perform experiments confirmed the reliability of the performance.

Research on the Multi-angle Measuring Service Quality for IPTV Quality Measurement

Provide a variety of services, from the current IPTV. However, in the service of new services such as real-time multi-angle quality measurement and verification work, there are few. Quality measures from the point of view of such subscriber are required. In this paper, we propose a way of measuring the quality of the IPTV multi angle. This service is a variety of services that can show when the cameras installed in various angles. IPTV service subscribers by the proposed method to measure how many complaints channel switching time measured by real-time IPTV services, and channel switching time multi angle comparison and analysis. Multi angle evaluation of services, and could seek to improve performance would be using it.

Web Contents Mining System for Real-Time Monitoring of Opinion Information

As the use of the Internet has recently increased, the demand for opinion information posted on the Internet has grown. However, such resources only exist on the website. People who want to search for information on the Internet find it inconvenient to visit each website.