• Journal of electromagnetic engineering and science
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• 제10권1호
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• pp.39-44
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• 2010

In this paper, a compact wideband antenna with a band-notch function is proposed. It operates over the UWB band with a band-stop characteristic. To increase the impedance bandwidth, a ring-shaped radiator is used. By attaching a circular stub to the ring-shaped radiator, the band-notch performance is obtained. The proposed antenna operates over a frequency range from 2.7 GHz to 11 GHz to satisfy the 10-dB return-loss requirement and provides band-stop performance in the frequency band from 5.15 GHz to 6.1 GHz. Experimental results reveal that the proposed antenna exhibits good radiation performance and is suitable for UWB applications.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.87-90
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• 1998

Many recent studies have been conducted involving the transport of constant and variable bit rate MPEG-2 video in asynchronous transfer mode (ATM) networks. In this study, the traffic control of supporting MPEG-2 video communications in ATM networks under unloaded or loaded network conditions, in which the generated traffic sources are bursty in nature, are considered. We analyse about MPEG-2 traffic and design a model, which makes use of the ATM OAM funcation in order to support the traffic control functions. To implement the model, we propose a scheme, which combines the performance management OAM function and the bandwidth allocation function. Especially, we design this scheme to control the VBR (Variable Bit Rate)MPEG-2 video traffic.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 제13회 신호처리 합동 학술대회 논문집
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• pp.389-392
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• 2000

In this paper, we propose a novel post processing method of deconvolution for SAR images based on phase extension inverse filtering, which improves spatial resolution as well as effectively eliminates sidelobes with low computational complexity. It extends the bandwidth only to control the magnitude of the processed SAR data without distortions of the phase in frequency domain unlike the other techniques such as spatially variant apodization (SVA), and other deconvolution techniques. We compare the image processed by the proposed method with images processed by uniform weighting function, Hamming weighting function whose coefficient is 0.75, and SVA.

• 한국통신학회논문지
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• 제22권6호
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• pp.1377-1384
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• 1997

We propose a new scheme to provide the fast forward and reverse(FF/R) functions to users in Video On Demand Service System. The proposed scheme is to use only I and P pictures obtained by sampling MPEG2 bit-steam. New frame raes for FF/R play are specified with parameters of MPEG2 syntrx. Bits of I and P pictures are reduced in three steps: Variable length decoding(VLD), Inverse quantization and Requantization. The proposed scheme is ecnomical in the sense that it can provide FF/R function without any additional requirement on the bandwidth and on the storage media in video server.

• 전자공학회논문지D
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• 제35D권5호
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• pp.11-17
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• 1998

In this paper, the synthesis procedufe of impedance matching network is presented for broad-band microwave amplifier design, whereby amplifier operating in the octave bandwidth is designed and fabricated in detail. The transfer function of the matching netowrks is synthesized by chebyshev approximation and element values for the networks of specified topology are calculatd for various MILs and ripples. After the transistor is modeled by negative-image device model, the synthesis procedure for matching networks is applied to broad-band amplifier design which has electrical performance of about 12dB gain in 4 to 8GHz range. Experimental results obtained from the fabricated amplifier are shown to approach the electrical performance designed in the given frequency range. Construction of the impedance matching networks by transfer function synthesis is very useful method for the design of broad-band microwave amplifiers.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2011년도 전기공동학술대회 논문집
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• pp.188-188
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• 2011

This paper describes the propagation characteristics of acoustic signals as a function of distance from the location of partial discharge(PD) occurrence to analyze correlation between discharge magnitude and acoustic signal in insulation oil. We fabricated a decoupler and an amplifier to measure acoustic signals produced by PD. The amplifier has the gain of 40 dB and the frequency bandwidth of 1.6 kHz~1.6 MHz. After a comparative calibration by a standard pulse generator and a coupling capacitor, we analyzed the propagation characteristics of acoustic signals in insulation oil as a function of distance.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.102-105
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• 1999

AAL type 2 provides for the bandwidth efficient transmission of low bit rate, short and variable packets in delay sensitive application. The service object for these networks ranges from POTS to multimedia conference. In this paper, we present one possible architecture which common part sublayer for new AAL type 2. The proposed CPS function has been achieved with on a FPGA The proposed architecture is faithful to the standardization of ITU-T and ATM-forum recommendation The proposed architecture applies to variable packet length from architecture CODECs for cellular network.. It's maximum process capability is 155Mbps with 256 CIDs. The architecture has sync./async. interface to application block and UTOPIA interface is used for physical layer interface.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.373-375
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• 1995

In this part a new window function is used to design a SAW band pass filter. As an example, we selected a 99.9 MHz 20-percent bandwidth 20-dB insertion loss filter and fabricated a device on 128$^{\circ}$ X-rotated $LiNbO_3$. The theoretical predictions of a design sample are compared with the experimental data and are shown to be in good agreement over the operating range.

• Journal of Power Electronics
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• 제7권1호
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• pp.1-12
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• 2007

Novel nonlinear backstepping control with integrated adaptive control function is developed for high-performance positioning control systems. The proposed schemes are synthesized by a systematic approach and implemented based on a modern low-cost DSP controller, TMS320C32. A baseline backstepping control scheme is derived first, and is then extended to include a nonlinear adaptive control against the system parameter changes and load variations. The backstepping control utilizes Lyapunov function to guarantee the convergence of the position tracking error. The final control algorithm is a convenient in the implementation of a practical 32-bit DSP controller. The new control system can achieve superior performance over the conventional nested PI controllers, with improved position tracking, control bandwidth, and robustness against external disturbances, which is demonstrated by experimental results.

• 한국정보처리학회논문지
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• 제7권5호
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• pp.1553-1558
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• 2000

The development of recent computer and communication technology has changed Automation System using communication network, and the new USB substituted with Serial Communication is already developed and now popular. In this paper, High speed data transfer system design using USB interface and communication application simulated for the situation is introduced. Base on USB, we can use additive function efficiently coped with former field device. The 'Winsock Connection USB Ternimal,' designed for hardware simulation, control the field device connected by USB, and provide the way for remote control of field device by Telnet connection through TCP/IP. That theorem can guarantee controlling direct input dta of user, and acuate function of field device using USB Packet Transmission. As a result of amy research, this communication application system identified good operation of field device with those of former field device. Another result of the experiment of hardware operation, we obtained accomplishment that the sufficient bandwidth guarantee of USB has high speed and high performance, and reduce the occupancy of system.