• 전기학회논문지
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• 제56권6호
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• pp.1105-1110
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• 2007

This paper describes an equivalent circuit modeling of 4-port connector system. A coupled transmission line was designed and fabricated, mimicking a 4-port connector system, and then S-parameters were measured using 4 port VNA (Vector Network Analyzer). The S-parameters from measurement and from Full-wave simulator coincided quite nice. By using these S parameters, an equivalent circuit parameters for a 4-port system was obtained. The time domain response from the equivalent circuit model matched to the signals, which was measured using TDR(Time Domain Reflectometry) meter. We were also convinced that there should be enough bandwidth to get a meaningful time domain result from Fourier inverse transformation of the S parameters. In addition, we applied the conversion algorithm to the 4-port connector system, which calculates the S-parameters of a 4 port system using the data from a 2-port VNA with the other ports open. Comparison of the two data, one from measurement and the other one from the conversion algorithm, was made in this manuscript.

• Journal of Mechanical Science and Technology
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• 제17권11호
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• pp.1616-1627
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• 2003

This paper describes a mini linear optical pickup actuator. To reduce the size, inner yokes are designed to guide the mover and outer yokes of permanent magnets are removed. Magnetic circuit method is used to determine the thrust force. Virtual path method is proposed to analyze the open magnetic circuit analysis. The magnetic circuit of the proposed actuator can be a closed circuit due to the virtual path model of the outer magnetic flux. The validity of virtual path method is evaluated by comparing to the FEM analysis. Structural vibration is investigated using FEM and the design of the mover is modified to improve the vibration characteristic. Dynamic characteristic experiments shows that the performance of the proposed actuator is enough to be used as a coarse and fine seeking actuator simultaneously and the thrust force margin for loading a focusing actuator is guaranteed.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 춘계학술발표대회 논문집
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• pp.241-246
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• 2008

In this paper, we analyze the I-V curve and hot-spot phenomenon caused by solar cells' serial and parallel connected circuit. The mis-match loss of parallel interconnection with low Isc string decrease lower than serially interconnected one and temperature caused by hot-spot does. Also, mis-match loss of parallel interconnection with low Voc string increase more than serially interconnected one. The string having low Voc happened hot-spot phenomenon when open circuit. The bad solar cell in string gives revere bias to good solar cell and make hot-spot phenomenon. If we consider the mis-match loss, when designing PV module and array. the efficiency of PV system might increase.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권11호
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• pp.550-556
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• 2001

The computerized cardiac analysis system, which acquires and analyzes the electrical activation signal propagating along the surface of the heart, is indispensible equipment for the open heart surgery and electrical cardiac study. In this paper, the design requirement and the electrical circuit analysis are performed to construct the multi-channel cardiac activation pre-amplifier necessary for a signal conditioning circuit. The general 64 channel configuration is expanded into 128 channels to enhance the spatial resolution on the mapped surface of the heart. The 128 channels pre-amplifier consists of input circuit, differential amplifier, right leg driven circuit and isolation part. It has distinct features; high voltage protection, leakage current limitation, isolation and the maximization of common mode rejection ratio with respect to the half-cell potential difference due to different electrode materials. The final pre-amplifier circuit is assembled with 8 boards, each of which composing of 16 channels.

• Educational Technology International
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• 제18권2호
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• pp.131-157
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• 2017

The purposes of the study were to investigate the participation of artists in paper circuit computing learning and to conduct an in-depth study on the formation and development of practical knowledge. To do this, we selected as research participants six artists who participated in the learning program of an art museum, and used various methods such as pre-open questionnaires, participation observation, and individual interviews to collect data. The collected data were analyzed based on community of practice theory. Results showed that the artists participated in the learning based on a desire to use new technology or find a new work production method for interacting with their audiences. In addition, the artists actively formed practical knowledge in the curriculum and tried to apply paper circuit computing to their works. To continuously develop the research, participants formed a study group or set up a practical goal through planned exhibitions. The results of this study can provide implications for practical approaches to, and utilization of, paper circuit computing.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.2000-2003
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• 2002

In this paper, an IC chip of a cell- network type circuit constructed with 1-dimensional chaos circuits is reported. The circuit, is designed by sing switched-current (Sl) techniques. In the proposed circuit, by controlling connections of cells, an S- dimensional circuit (S ＝ 1, 2, 3,…) and a synchronization system can be constructed easily. Furthermore, in spite of faults of a few cells, the circuit can reconstruct above-mentioned systems only to change connections of cells. This feature will open up new vista for engineering applications which are used in a distance place such as space, deep sea, etc. since it is difficult to repair faults of these application systems. To investigate the characteristics of the circuit, SPICE simulations are performed. The VLSI chip is fabricated from the layout design using a CAD tool, MAGIC. The proposed circuit is integrable by a standard 1.2 $\mu\textrm{m}$ CMOS technology.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.190-199
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• 2014

In the last years, fault problem in power electronics has been more and more investigated both from theoretical and practical point of view. The fault problem can cause equipment failure, data and economical losses. And the analyze system require to ensure fault problem and also rectify failures. The current errors on these faults are applied for identified type of faults. This paper presents technique to detection and identification faults in three-phase voltage source inverter (VSI) by using time-frequency distribution (TFD). TFD capable represent time frequency representation (TFR) in temporal and spectral information. Based on TFR, signal parameters are calculated such as instantaneous average current, instantaneous root mean square current, instantaneous fundamental root mean square current and, instantaneous total current waveform distortion. From on results, the detection of VSI faults could be determined based on characteristic of parameter estimation. And also concluded that the fault detection is capable of identifying the type of inverter fault and can reduce cost maintenance.

• Journal of Power Electronics
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• 제12권1호
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• pp.208-214
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• 2012

This paper presents a novel approach based on the loci of instantaneous symmetrical components called "Wing Shape" which requires the measurement of three input stator currents and voltages to diagnose interturn insulation faults in three phase induction motors operating under different loading conditions. In this methodology, the effect of unbalanced supply conditions, constructional imbalances and measurement errors are also investigated. The sizes of the wings determine the loading on the motor and the travel of the wings while their areas determine the degree of severity of the faults. This approach is also applied to detect open circuit faults or single phasing conditions in induction motors. In order to validate this method, experimental results are presented for a 5 hp squirrel cage induction motor. The proposed technique helps improve the reliability, efficiency, and safety of the motor system and industrial plant. It also allows maintenance to be performed in a more efficient manner, since the course of action can be determined based on the type and severity of the fault.

• 한국전자파학회논문지
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• 제20권10호
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• pp.1091-1096
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• 2009

본 논문에서는 공진 MTM-TL(Metamaterial Transmission Line) 등가 회로를 이용하여 방사 및 회로 파라미터의 추출 식을 제시하였다. 특히 개방 또는 단락 상태에서 방사 소자인 직렬 $R_0$와 병렬 $G_0$를 EM 시뮬레이션 또는 측정을 통해 얻은 S-parameterd(|$S_{11}$|)를 이용하여 추출한다, EM 시뮬레이션의 결과, 추출한 파라미터를 이용한 회로 시뮬레이션의 결과 그리고 측정 결과가 매우 일치함을 확인하였다.

• 대한전자공학회논문지SD
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• 제41권12호
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• pp.21-26
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• 2004

본 논문에서는 package된 BJT의 RF 등가회로 모델을 optimization과정 없이 직접 추출하는 방법을 개발하였다. 먼저, open 과 short package 구조를 사용하여 plastic package의 기생성분을 측정된 S-파라미터로부터 정확히 제거하였다. 이와 같이 package do-embedding된 S-파라미터로부터 package lead와 chip pad 사이의 bonding wire 인덕턴스와 chip pad 캐패시턴스를 직접 추출하는 간단한 방법을 구축하였다. 그 후에 내부 BJT소자의 소신호 모델변수들은 RF 등가회로로부터 유도된 Z나 Y-파라미터 방정식을 이용하여 결정하였다. 이 방법으로 모델화된 packaged BJT의 S-파라미터는 측정 데이터와 아주 잘 일치하였으며 이는 새로운 추출방법의 정확성을 증명한다.