• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.8
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• pp.1485-1492
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• 1994

In this paper, we design and implement the Combline Bandpass Filters for the satellite transponder by using the least-squares curve-fitting method. The Combline Bandpass Filters are located front of the mixer and behind of it, which is the component of down converter. Comparing with the filters which have $\lambda$/4 resonance length. Combline Filter has wide range of stop-band by using $\lambda$/8. So, it is useful to the satellite transponder owing to its low mass and small size. The filters described are realized as coupled rectangular coaxial transmission lines. The choice of this type is due to the ease of machining and wide variations in coupling coefficients rather than the use of the round rod resonators. We determine 800 MHz bandwidths for the combline bandpass filters. By using Chebyshev filter function, we design and implement 4-pole combline filters.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.384-387
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• 2010

지상파 방송이 아날로그에서 디지털 방송으로 전환됨에 따라 아날로그 TV 방송신호와 디지털 TV(DTV) 방송신호간의 생성과 복조방식이 상이함에 따라 전파환경에 의한 방송품질의 변화가 예상된다. 따라서 DTV 방송신호의 수신을 위한 전파 음영지역 해소가 품질 확보에 필수적인 관심사로 대두되고 있으며, 이에 대한 대책으로 타당성 및 신뢰성 있는 전계강도 예측 방법에 근거하여 적정지역의 송신소 및 중계기 설치가 전파 품질 개선에 크게 기여할 것으로 여겨진다. 본 논문에서는 국제적으로 30 MHz ~ 3000 MHz 대역 지상파 방송서비스의 전파특성 예측에 활발히 이용되는 ITU-R 권고 P.1546 전파모델을 이용하여 점-대-지역 전계강도 예측을 위한 계산 방법을 제시하고, 수치 계산 결과를 비교 및 분석한다. 제시된 방법은 DTV 수신지역의 전계강도 예측을 통한 신호의 품질 분석은 물론, 양호한 전파환경 구축에 필요한 중계기 위치설정, 인접대역에 의한 간섭 및 양립성 분석 등에 직접 활용이 가능하다.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.1
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• pp.39-48
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• 2003

A GPS translator system is used to get the precise and reliable trajectory data for the high dynamic test vehicles, such as missiles or artillery shells. The missile system with high dynamics, vibration and shock needs to determine its position and velocity in particular. The proposed GPS translator on the test vehicle receives GPS signals, amplifies, down-converts, digitally samples, BPSK modulates, up-converts them to S-band, and then retransmits them to the ground translator processing station. It has doppler variation and signal noise, so design method for resolving them is proposed. The performance of the translator is proved by environmental test and real flight test.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.715-717
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• 2012

최근 대용량 모바일 트래픽을 효율적으로 처리하고 다양한 5세대 지식 서비스를 제공할 수 있는 차세대 이동통신 기술개발을 목표로 중추 네트워크라는 개념이 고려되고 있다. 중추 네트워크에서는 시스템 용량을 기존 이동통신 시스템 대비 크게 증대시키기 위하여 밀리미터파 대역에서 넓은 대역폭을 사용하고 빔형성 기술을 통하여 무선자원을 재사용한다. 그러나 밀리미터파 대역은 직진성이 매우 강하기 때문에 비가시거리 통신영역에서 통신 품질이 급격히 저하되는 문제점이 발생하며, 이를 해결하기 위해 중추 네트워크에서는 적절한 위치에 중계기를 설치하여 비가시거리 통신영역을 최소화하는 것을 고려한다. 본 연구에서는 기지국 및 중계기 위치에 따른 중추 네트워크의 성능을 분석하기 위해 개발된 시스템 레벨 시뮬레이터를 소개한다. 본 시뮬레이터는 중추 네트워크의 통신영역과 채널용량을 분석 및 연구하는데 크게 기여할 수 있을 것으로 기대된다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.51-55
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• 2015

In this paper, we proposed scheme that obtain diversity gain in the cooperative communication to mitigate, applied to the effects of fading in the vehicle communication. Relay used bus that can available in the city environment. In addition, we applied the double rayleigh fading environment so that can applied in real-environments. Therefore, proposed scheme through this paper applied to vehicle communication, user can acquire a high quality service and the operation efficiency of the network is improved. Finally, performance of the proposed protocol is analyzed in terms of bit error rate.

• Journal of IKEEE
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• v.27 no.4
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• pp.411-417
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• 2023

Unmanned aerial vehicle (UAV)-assisted relay has the advantages of ease of deployment, good communication channels, and mobility over traditional terrestrial relay, which greatly improves wireless connectivity. In this paper, we design a UAV-enabled relay network that can utilize radio frequency bands to harvest energy from sources and utilize terahertz (THz) bands to transmit information between secondary transmitters and receivers. Next, we solve the optimal position of the UAV that maximizes the relay channel capacity, and propose an algorithm to design two trajectories of UAV (a straight and an elliptical trajectory) using the derived solution. Numerical results show that the straight trajectory is better in terms of harvested energy and channel capacity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2293-2302
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• 2012

New optical transmission links technique for compensating of the distorted wavelength division multiplexed (WDM) signals due to group velocity dispersion (GVD) and self phase modulation (SPM) in single mode fiber (SMF) are proposed. The proposed optical links have optical phase conjugator (OPC) placed at nearby WDM transmitter or receiver and repeater spans with artificial distribution of SMF length and residual dispersion per span (RDPS). It is confirmed that optimal link configuration expanding effective launching power range and effective net residual dispersion (NRD) by improving system performance is that having OPC closely placed at WDM receiver and the gradually descended distribution of SMF length and RDPS of each repeater spans, related with the gradually increased optical link length. And, it is also confirmed that NRD is controlled by postcompensation in optimal optical link with OPC closely placed at WDM receiver.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.723-725
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• 2013

The compensation characteristics are investigated as a function of the position an optical phase conjugation (OPC) in the optical transmission links with a randomly distributed residual dispersion per span (RDPS). The simulation results show that the optimal net residual dispersion (NRD) is decided to be 10 ps/nm and -10 ps/nm by precompensation and postcompensation, respectively, which are independence of the OPC positions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.301-303
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• 2012

In this Paper, we are implemented position awareness system based on one-pass tag. This system are combined ZigBee and RFID technology. We developed the solution to detect of user's position using position awareness receiver and repeater. This location recognition includes parked car location tracking, coming in and out car, automation of immigration control, enhanced security through emergency call, and automatic invocation elevator control and etc.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.53-58
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• 2011

In this paper, we firstly propose a novel cooperative transmission protocol, which utilizes the advantages of mid-notes in the route from the source to the destination. Taking benefits from balancing between the received packet from the source and acknowledge message from the destination, the mid-node between the source and the destination is firstly considered to be the broadcaster. If its signal is successfully received from the source, it leads to consider the next nodes, which has closer distance to the destination than it. If one of these nodes correctly receives the signal, it performs broadcasting the signal to the destination instead of mid-node. Otherwise, the mid-node directs attention to these nodes being near to the destination. As the result, some nodes are unnecessary to be considered and passed over time. After that, we analyze some published selection relaying schemes based on geographic information to choose the best nodes instead of the instantaneous SNR as before. Finally, simulation results are given to demonstrate the correctness of the performance analyses and show the significant improvement of the selection relaying schemes based geographic information compared to the other ones.