• 한국통신학회논문지
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• 제30권10A호
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• pp.922-929
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• 2005

본 논문에서는 직접대역 확산 통신 기법을 사용하는 이동통신 시스템에서 하향링크상의 무선신호를 이용하여 오버헤드 채널상의 정보를 취득하고 이 정보를 이용하여 파일롯 채널을 생성함으로써 기지국 간 하드핸드오프를 가능하게 하는 적응형 파일롯 비콘 장치를 제안한다. 본 적응형 파일롯 비콘 장치는 무선 신호 중에서 파일롯 채널 만을 선별하여 생성 및 전송하므로 상대적으로 낮은 전력으로 서비스가 가능하며, CDMA 수신부에서 하향링크상의 파일롯 채널로부터 기지국의 시간동기 및 주파수 동기를 획득하여 장치의 오프셋을 보정하므로 GPS에 의한 시간동기가 필요하지 않으며 기지국 순방향 신호의 수신이 가능한 임의의 장소에 설치가 가능한 장점이 있다. CDMA수신기에서 하향링크 파일롯 신호를 탐색하는 파일롯 서처는 FPGA와 DSP를 이용하며, FPGA에서 구현된 파일롯 서처는 초기동기 획득용으로 사용되곤 DSP에서 구현되는 파일롯 서처는 비콘장치의 클럭과 기지국 장치의 클럭사이에 발생하는 오프셋 오차를 보정하는 역할을 수행한다. 적응형 파일롯 비콘 장치의 CDMA 송신부는 CDMA 수신부에서 취득한 파일롯 채널의 시간정보인 타임오프???V을 이용하여, 기지국에 동기된 하향링크 파일롯 신호를 생성한다. FIR필터를 통하여 출력된 1차 중간주파신호는 RF모듈웨서 상향변환된 후 고출력증폭기와 안테나를 통하여 방사하게 된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권1호
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• pp.108-118
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• 2009

In this paper we develop an indoor location tracking system and its 3D tracking monitoring viewer, viz., 3D Navigation Viewer (3DNV). We focus on the integration of an indoor location tracking system with the Virtual Reality Modeling Language (VRML), to facilitate a representation of the user's spatial information in virtual indoor environments that is synchronized with the physical location environment. The developed indoor location tracking system employs beacons as active transmitters, and a listener as a passive receiver. The distance information calculated from the difference speeds of RF and Ultrasonic signals is exploited, to determine the user's physical location. This is essential in supporting third parties like doctors and caregivers in identifying the activities and status of a particular individual via 3DNV. 3DNV serves as a unified user interface for an indoor location tracking system, showing the viewpoint and position of the target in virtual indoor environments. It was implemented using VRML, to provide an actual real time visualization of the target's spatial information.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.667-670
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• 2004

In this paper, we have presented the improved IF transceiver architecture and the implementation and experimental results on re-configurable transceiver based on digital IF for multiple wideband OFDM/TDD base stations for high-speed portable internet-service in which is issued Korea. The implemented IF transceiver has been designed to support multiple frequency allocations and multiple standards by only modifying the programmable software not its hardware like as the software-defined-radio concept. Also, the digital complex quadrature modulation technique has been used for the digital IF transmitter, which is able to combine multiple frequency bands in digital processing block not RF block and to reject the image frequency signals. And the bandpass sampling technique has been used for the digital IF receiver to reduce the sampling rate of ADC. This paper has shown the experiment results on the frequency response and constellation on the base-station implemented using the modified IEEE 802.16a/e physical layer channel structure based on OFDM/TDD.

• 대한전자공학회논문지TC
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• 제48권2호
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• pp.90-94
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• 2011

본 논문에서는 고주파 대역 중에서 에너지 전송과 관련되어 정류 회로의 구조와 특성을 분석하고, 최대의 효율을 이끌어 낼 수 있는 방안을 찾고자 한다. 13.56MHz에서의 입력 신호를 DC 변환하여 실험 및 측정을 하였다. 정류회로는 반파 정류회로, 전파정류회로 브릿지 정류회로로 나눌 수 있고, 최대 효율을 갖기 위해서 다양한 정류 회로를 전산 모의 실험하였다. 현재까지의 연구 내용은 passive 소자를 이용한 효율 개선에 중점을 두고 실험을 하였다. 정류 효율에 영향을 미치는 요소는 소자의 특성에 좌우하며, 이번 실험에서는 약 70%의 효율을 측정할 수 있었으며, 보다 개선된 소자를 사용함으로서 낮은 입력에서 높은 효율을 얻을 수 있었다.

• 한국항공우주학회지
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• 제32권10호
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• pp.127-133
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• 2004

본 논문은 무인항공기의 자동비행을 위한 이동형 지상제어 시스템 개발에 관한 연구이다. 본 연구에서는 휴대와 이동을 수월하게 하기 위한 이동형 지상제어시스템 (PGCS)을 개발하였다. 일반적으로 지상제어시스템은 항공기가 수행해야할 임무정보를 전송하고, 원활한 조종을 위하여 항공기 위치, 자세, 상태, 항법 정보를 항공기로부터 실시간 수신할 수 있어야 한다. 이동형 지상제어시스템 구성은 노트북 컴퓨터, 지상제어시스템과 항공기간의 통신을 위한 모뎀, 입/출력 보드, 무선조종 수신기 그리고 여러 개의 스위치와 LED 램프로 구성된다. 소형 무인항공기를 이용한 비행시험으로서 본 연구에서 개발한 이동형 지상제어시스템 성능 검증을 수행하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권4호
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• pp.1502-1519
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• 2020

Recently, new devices have been developed for the Internet of Things concept. The devices commonly use RF (Radio Frequency) based wireless communication. With the increase in the number of devices, the space allocated for the radio frequency band in wireless communication fills rapidly. Visible Light Communication (VLC) is an alternative, secure and economical communication technology that uses light instead of radio frequencies. While Web of Things (WoT) is the adaptation of the experience and knowledge acquired from the web into the internet of things ecosystems. By combining these two technologies, the development of the Visible Light Communication for Web of Things (VLC4WoT) system, which can use VLC and WoT technologies, has been our motivation. In our study, microcontroller control circuit was created for VLC4WoT system. Control of the circuits over the internet was performed. VLC based receiver and transmitter units have been developed for wireless communication. Web based interface was created for control. The test apparatus consisting of four objects with four outputs and a transfer unit was carried out. In this test, communication was achieved successfully. It was presented in the study that VLC can be used in the web of things architecture. In the future, it is envisaged to use this system as a safe and economical system in indoor environments.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.31-33
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• 2003

Recently, KARI developed in-house meteorological sensor processing system named MESIS for GOES GVAR 5-CH Imager for better KOMPSAT EOC mission operation. MESIS consists of antenna system, receiver, serial telemetry card, processing and mapping software, and 2 NT PC systems. This paper shows system requirement, system design, characteristic and test results of processing system. System operation concept and sample image are also provided. Implemented system was proven to be fully operational through lots of operations covering from RF signal reception to web publishing.

• 전기학회논문지
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• 제61권10호
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• pp.1483-1488
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• 2012

This paper analyzed the precision and accuracy of the altitude-aided GNSS using the altitude information from digital map. The precision of altitude-aided GNSS is analysed using the theoretically derived DOP. It is confirmed that the precision of altitude-aided GNSS is superior to the general 3D positioning method. It is also shown that the DOP of altitude-aided GNSS is independent of altitude bias error while the accuracy was influenced by the altitude bias error. Furthermore, it is shown that, since the altitude bias error influenced differently to each pseudorange measurement, the effect of the altitude bias error is more serious than clock bias error which does not influence position error at all. The results are evaluated by the simulation using the commercial RF simulator and GPS receiver. It confirmed that altitude-aided GNSS could improve not only precision but also accuracy if the altitude bias error are small. These results are expected to be easily applied for the performance improvement to the land and maritime applications.

• 로봇학회논문지
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• 제4권1호
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• pp.1-9
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• 2009

Radio Frequency Identification (RFID) is an automatic identification method. Information such as identification, logistics history, and specification of products are written and stored into the memory of RFID tags (that is, transponders), and retrieved through RF communication between RFID reader device and RFID tags. RFID systems have been applied to many fields of transportation, industry, logistics, environment, etc in order to improve business efficiency and reduce maintenance cost as well. Recently, some research results are announced in which RFID devices are combined with other sensors for mobile robot localization. In this paper, design of multi-protocol baseband for RFID reader device is proposed, and the baseband modem is implemented into SoC (System On a Chip). The baseband modem SoC for multi-protocol RFID reader is composed of several IP (Intellectual Property) blocks such as multi-protocol blocks, CPU, UART(Universal Asynchronous Receiver and Transmitter), memory, etc. As a result, the SoC implemented with FPGA(Field Programmable Gate Array) is applied to real product. It is shown that the size of RFID Reader module designed with the FPGA becomes smaller, and the SoC chip price for the same function becomes cheap. In addition, operation performance could be the same or better than that of the product with no SoC applied.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.289-291
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• 2007

The Digital Multimedia Broadcasting(DMB) system is developed to offer high quality audio-visual multimedia contents to the uses by the various portable terminals in the mobile environment. Integrated complex reception platform is required to receive multimedia broadcasting services transmitted from various transmission media. In this paper, we present the design and implementation technic for providing the both of terrestrial and satellite DMB services simultaneously using the same hardware platform. The implemented complex receiving terminal to accommodate these DMB services simultaneously need composed of it RF module. it baseband module, it complex control module and the complex de-multiplexer module. The complex control module is designed using uClinux operating system. The complex de-multiplexer, which perform the functions of the address decoder and each DMB stream de-multiplexer, is implemented. with FPGA device. The implemented platform is tested in a real environment and its performance is satisfied with required performance criteria.