• Proceedings of the KIEE Conference
• /
• 1999.07c
• /
• pp.1440-1443
• /
• 1999

This paper proposes fault detection method using a neural network & fuzzy logic on distribution lines. Fault on distribution lines is simulated using EMTP. The pattern of high impedance fault on pebbles, ground and short-circuit fault were take as the learning model. In this paper proposed fault detection method is evaluated on various conditions. The average values after analyzing fault current by FFT of even odd harmonics and fundamental rms were used for the neural network input. Test results were verified the validity of the proposed method

• Proceedings of the KIEE Conference
• /
• 1993.11a
• /
• pp.6-8
• /
• 1993

Short Circuit analysis is one of the most fundamental procedures for power system analysis problem. In order 10 solve the problem, In order to solve the problem, it's required to develop an advanced algorithm by which modified bus admittance matrix are easily computed for a large number of alternative network configuration. This paper proposes a new calculation method to efficiently modify the bus impedance matrix elements of large power system by method for removal of link, and presents its Practicality by applying the proposed method in the power system model.

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10a
• /
• pp.962-967
• /
• 1991

A counter balance valve is used as one part of hydraulic motor brake system. The function of this valve is to protect over-run or free falling of inertia load. But occasionally the brake system with counter balance valve makes some undesirable problems such as pressure surges or vibrations. In this study, for the purpose of easy estimation about dynamic characteristics of hydraulic system including counter balance valve, precise formulation describing fluid dynamics and valve dynamics under various boundary conditions were made. Dynamic characteristics were analysed by numerical integration using Runge-Kutta method, because the equations in this circuit with counter balance valve contain various nonlinear terms. Propriety of this analysis method is verified by experiment. For the purpose of obtaining fundamental data for preventing instability, this study experimented the effects of the spool taper, spring constant, cylindrical choke. And we developed double acting brake system integrated counter balance valve.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.11 no.1
• /
• pp.47-51
• /
• 1974

In this paper, we have tried to study topological method for generating trees and Co-trees of a given circuit which is required in the first step of analysis of networks, and also illustrative examples that compare with other available methods in aspect of the efficiency are given. It is believed that the proposed method is more efficient than other methods already available and that it will play a fundamental role in the topological analysis of electrical networks.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.436-437
• /
• 2010

전력전자공학의 목적은 전자적인 스위치를 이용하여 전력을 원하는 대로 변환하는 것이다. 전력전자시스템을 제어하려면 스위치 동작과 교류회로의 동적특성을 이해해야 한다. 본 논문에서는 전력전자의 핵심이 되는 기술사상(技術思想)을 다음 2가지로 정리하였다. 1) 모든 전자 스위치는 등가적으로 정확히 시변 선형 또는 비선형 전자변압기다. 2) 모든 교류회로의 정적 또는 동적 특성은 페이저변환으로 해석가능하다. 이번 논문에서 일반화된 전자변압기 모델을 제시하고, 단상 및 다상을 통합하고 D-Q회로변환과 양자회로변환(quantum circuit transformation)을 모두 포용하는 일반화된 페이저변환을 제시한다.

• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.33-35
• /
• 1999

This paper describes the test results of the single phase 3kVA high temperature superconducting power trans-former. The tapes are made with Bi-2223 and have silver alloy as the matrix. Four double pancake windings are used in total. Among them two double pancake windings are connected in series for high voltage winding and two double pancake windings are connected in parallel for low voltage winding. The rated voltages of each winding are 220/110 V. Fundamental characteristics are obtained through short circuit and no load tests. The over load capability and characteristics are investigated.

• Proceedings of the KOSOMBE Conference
• /
• v.1998 no.11
• /
• pp.153-154
• /
• 1998

As the fundamental study to set up the algorithm of the X-ray dosimeter, we obtained the data using the designed X-ray input circuit and the semiconductor sensor. We measured the data of the ten time in the various kVp, mA and sec and then the obtained each data is averaged. After the data obtained under the circumstances of total 600, these data saved the database. We developed the algorithm of the X-ray dosimeter using the saved data. Later the result of this study is so important to design X-ray dosimeter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.11a
• /
• pp.270-273
• /
• 1996

This paper describes a type of piezoelectric transformer with improved design principles. It consists of a thin rectangular piezoelectric ceramic plate having two input electrodes and one output electrode. The length of each input and output electrode is nearly one third of that of piezoelectric transformer itself. In the driving section, the ceramic plate is poled in the thickness direction reversely with each other, and has electrodes on both main faces. The electric input near its fundamental resonance frequency is applied to the driving section in parallel and the output voltage from the generating section is connected to the resistor load. Its equivalent circuit is derived from the Mason\`s model. The frequency characteristics near the resonance frequency under no load have been investigated. Moreover, using this piezoelectric transformer we measured the LCD backlight characteristics.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.13 no.8
• /
• pp.701-709
• /
• 2001

In this days, heat pipe heat sink has been widely applied to power controllers for railway substations to remove heat from power semiconductors(diodes or thyristors). The heat pipe heat sink consists of a aluminum heating block for mounting the thyristor, 2~3 heat pipes and large number of aluminum fins. The present study was to get fundamental informations of the structure, design parameters and heat transfer performances of heat pipe heat sink. Series of operational test for a unit with 3 heat pipes were performed and its heat flow circuit was analysed from the experimentally obtained data on wall temperature distribution. Total resistance was ranged 0.02~$0.03^{\circ}C$/W for a power range from 40W to400W. The time to get the steady state was approximately longer than 20 minutes, and overshooting was not occurred during start up operation.

• International Journal of Railway
• /
• v.5 no.4
• /
• pp.167-174
• /
• 2012

As wireless power transfer (WPT) technologies emerge in a wide range of applications including public transportation, many expect that applying the technology to the current railway systems will bring positive effects to current railway systems. In this paper, we introduce design methodology of a WPT system for railway application. Fundamental principles of magnetic fields and a WPT circuit are first analyzed, and advantages and efficiency of a possible train system are discussed. It then examines other significant factors such as performance requirements and EMC criteria to design a wireless train system.