• Journal of information and communication convergence engineering
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• v.9 no.5
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• pp.483-486
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• 2011

In this study, a fan-beam microstrip array antenna for an X-band radar was designed and fabricated using a novel technique. A microstrip array structure was used to obtain a high-gain and narrow horizontal beam-width. The feeding point is located at the center of the antenna because of its $360^{\circ}$ rotational characteristic. The measured results indicate a gain of 23dBi, and a horizontal and vertical beamwidth of $3.57^{\circ}$, $26.12^{\circ}$, respectively. The proposed antenna performed adequately and managed to meet the specifications.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1944_1945
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• 2009

In this research, the bidirectional-communication-media-system which is not able to implement by using the existing coaxial cable was manufactured and the method applicable to Educational Environment was proposed. Also, it is implemented that we can use various media contents through narrow bandwidth by network-linking. The unified broadcasting system applicable to Educational Environment based on IPTV was implemented in the last.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.869-873
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• 1987

In this study, we have examined the multi-level QPRS system in point of error rate, which requires narrow bandwidth and has Little ISI. The generalized error rate equations of multi-level QPRS signal have been derived in the presence of Gaussian noise and co-channel CW interference. And the error rate performance of 9, 49, 225 QPRS system is investigated as parameters of carrier power-to-noise power, carrier power-to -interference power. Also, we have investigated the effect of carrier offset.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.854-858
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• 1987

This paper considers impulsive noise which produce burst error in high speed(approx.160Kbps) data transmission like ISDN(Integrated Servise Digital Network) using PSTN(Public Switching Telephone Network). To begin with, we obtains the transfer function of subscriber line to calculate the variation of bandwidth when the gain of receiver is fixed and channel capacity of non-gaussian channel in upper-and lower bound, and evaluates the transmission capability. In this paper compares channel capacity bounds which obtains when probability density function of impulsive noise is Laplacian distribution function with impulsive noise generated by waveform synthesier.

• Convergence Security Journal
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• v.7 no.1
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• pp.99-106
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• 2007

We propose a distributed anchor Crossover Switches (CX) searching algorithm to play an important role in ensuring fast and seamless handoff control in wireless ATM networks. Within networks that are grouped together, connection management is done for each group by anchor switches, and Permanent Virtual Circuit (PVC) with a narrow bandwidth is assigned between anchors for exchange of information. The proposed algorithm enables quick searching of a targeted CX, makes management of the overall network easier, and reduces system overhead or propagation delay time, thus providing fast and seamless handoff.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.8
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• pp.1305-1309
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• 2002

Subsurface radar characterize a broadband frequency to collect a information, such as a crack of building, because of using narrow pulse. In this paper, we design a broadband bowtie antenna, using a microstrip, with a FR-4 substrate of ${\varepsilon}_r=4.0$, t=1.6mm. It has a 9.31% bandwidth at s11<-10 dB and s11=-27.45 dB, VSWR=1.089 at 5.78GHz.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.50.6-50
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• 2002

In this paper, the relationship between a slave robot and the uncertain remote environment is modeled as the impedance to generate the virtual force to feed back to the operator. For the control of a teleoperated mobile robot equipped with camera, the teleoperated mobile robot take pictures of remote environment and sends the visual information back to the operator over the Internet. Because of the limitation of communication bandwidth and narrow view-angles of camera, it is not possible to watch the environment clearly, especially shadow and curved areas. To overcome this problem, the virtual force is generated according to both the distance between the obstacle and robot and the approachin...

• Electronics and Telecommunications Trends
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• v.9 no.4
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• pp.131-138
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• 1994

최근 무선통신의 활성화에 따라, V/UHF(very/ultra high Frequency) 대역에서 한정된 주파수를 효율적으로 이용하기 위한 방법의 하나로서, 점차 점유 주파수 대역의 폭을 축소하여 보다 많은 이용자를 수용하도록 무선 채널의 협대역화가 추진되고 있다. 본 고에서는 먼저 V/UHF 대역 무선 통신에서 채널의 협대역화에 관련된 기술 중에서 현재까지 사용되고 있는 FM(frequency modulation), AM(amplitude modulation) 변조 방식의 장,단점을 살펴본후, 새로운 LM(linear modulation) 변조 방식에 대한 기술적 배경 및 특성을 알아보았다. LM은 SSR(single side band)-AM이 발전한 것으로서, TTIB(transparent tone-in-band), CLT(Cartesian loop transmitter), FFSR(feed-forward signal regeneration), DSP(digital signal processing)등 4가지의 기술이 결합하여 만들어진 것이다. LM 방식에 사용된 4가지 기술을 소개하고, 기존의 변조 방식에 비해 개선된 사항에 대해 서술한다.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.15-18
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• 2006

We have proposed a broadband analog feedforward optical transmitter using a wideband $180^{\circ}$ hybrid coupler instead of conventional frequency-sensitive phase shifter with the narrow bandwidth property using a wideband $180^{\circ}$ hybrid coupler, the wide-band linearization technique enhances the linearity of the feedforward optical transmitter. In two-tone cases, the $3^{rd}-IMD$ products was enhanced more than 10 dB in 385 MHz range(1.375$\sim$l.76 GHz).

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.8
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• pp.400-405
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• 2001

Quadrature Amplitude Modulation(QAM) is well known a bandwidth efficient modulation scheme. However, its use for mobile communications has been limited due to noise and signal distortion. Recently, the QAM scheme is emerging as a new modulation scheme for a band-limited wireless system. In this paper, we propose an iterative decoding algorithm assuming QAM signal for a narrow-band mobile channel. The Algorithm is based on the EM(Expectation Maximization) Algorithm, and the performances of the proposed decoder are assessed using computer simulation. The simulation results show that the proposed decoder perform better compared to that of other schemes.