• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.89-90
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• 2008

We present an implementation and it's real-sea test of an underwater acoustic communication system, which allows the system to reduce complexity and increase robustness in time variant underwater environments. For easy adaptation to complicated and time-varying environments of the ocean, all-digital transmitter and receiver systems were implemented. For frame synchronization the CAZAC sequence was used, and QPSK modulation/demodulation method with carrier frequency of 25kHz and a bandwidth of 5kHz were applied to generate 10kbps transmission rate including overhead. To improve transmission quality, we used several techniques and algorithms such as adaptive beamforming, adaptive equalizer, and convolution coding/Viterbi decoding. For the verification of the system performance, measurement of BER has been done in a very shallow water with depth of 20m at JangMok, Geoje. During the experiment, image data were successfully transmitted up to about 9.6km.

• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.98-107
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• 2003

In this study, a survey of time synchronization methods between the remote places. Generally, there are many kinds of time synchronization methods for distant places and they can be grouped three categories according to the type of time transfer methods. The three methods are ground based network, GPS/NAVSTAR and geostationary satellite. Especially, the relay base stations for wireless digital communication are operated based on the timing signal service of the GPS/NAVSTAR satellite network. And as the back-up of the timing signal service of the GPS/NAVSTAR, the geostationary satellite based time synchronization method have researched. In this short paper, the brief explanations about each category were presented.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.86-93
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• 2004

This paper presents the remote measurement of the ECU signals adopted with KWP 2000 protocol using the wireless communication technique of bluetooth. The bluetooth technology will be the most promising network paradigm which can open the new area in the information technology. Especially, bluetooth module is able to link all the electrical products and personal computers to cellular phone or PDA. This research has a try to design a wireless measurement model of ECU signal based on the car telemery system using bluetooth device. In order to measure the ECU signals, we designed the interface circuits which is able to communicate between the ECU system and the terminal circuits according to the ISO, SAE regulation of communication protocol standard. A microprocessor S3c341 OX is used for the system control and communication of ECU signals. The embedded system software is programmed to measure the ECU signals using the ARM compiler and ANCI C based on Micro/OS-II kernel to communicate between two bluetooth modules using bluetooth stack. The remote measurement of ECU signals using the bluetooth was designed and implemented to evaluate the performance of wireless network to the transmit measurement data. The possibility for the remote measurement of the self diagnosis signals of ECU adopted with KWP2000 protocol verified through the developed systems and algorithms in embedded system.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.98-104
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• 2013

This paper presents a WBAN UWB receiver circuit for RTLS(real time location system) and wireless data communication. The UWB receiver is designed to OOK modulation for energy detection. The UWB receiver is designed for sub-sampling techniques using 4bit ADC and DLL.The proposed UWB receiver is designed in $0.18{\mu}m$ CMOS and consumes 61mA with a 1.8V supply voltage. The UWB receiver achieves a sensitivity of -85.7 dBm, a RF front-end gain of 42.1 dB, a noise figure of 3.88 dB and maximum sensing range of 4 meter.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.899-902
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• 2005

언제, 어디서, 누구나 대용량 네트워크를 사용할 수 있는 유비쿼터스(ubiquitous) 시대가 다가오면서, 카메라가 장착되어 있고 무선 통신이 가능한 PDA, 웨어러블(wearable) 컴퓨터와 같은 휴대용장치가 가까운 미래에는 일상의 한 부분이 될 것이다. 이런 상황을 반영하듯, 휴대용 장치를 이용하여 실감형 게임(augmented game)을 수행하는 다양한 연구가 진행되어 왔다. 기존의 실감형 게임들은 전통적인 ‘backpack’ 시스템을 이용하거나 패턴마커(pattern marker)를 이용하였다. ‘backpack’ 시스템은 비싸고, 거추장스러우며, 사용하기 불편한 단점을 가지고 있으며, 패턴마커를 이용하면 미리 정한 장소에서만 게임을 즐길 수 있는 단점을 가지고 있다. 본 논문에서는 Flying Cake이라는 실감형 게임을 소개하며, 거추장스러운 장비 대신, 가볍고 휴대 가능한 PDA를 이용하여 게임을 수행하며, 실제 세계에서 가상의 물체를 접목할 위치를 지정하기 위해, 미리 정해져 있는 패턴마커 대신 얼굴 영역을 이용한다. Flying Cake은 연산자원이 부족한 PDA에서 실시간으로 얼굴 영역을 찾기 위해 스킨칼라(skin-color) 모델과 CAMShift 알고리즘을 이용하며, PDA상에서 카메라를 이용하여 실제 세계와 가상의 물체 사이의 상호작용을 제공하는 새로운 게임 패러다임(paradigm)을 통해 사용자에게 새로운 즐거움을 제공한다.

• 한국공간정보시스템학회:학술대회논문집
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• 2002.03a
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• pp.65-70
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• 2002

도로표지는 도로 이용자에게 목적지까지의 방향, 거리, 경로 안내 등 기타정보를 제공함으로써 안전하고 원활한 교통흐름을 제공하여 도로의 이용 효율을 극대화할 수 있는 중요한 도로 부속시설물이다. 이 시설물의 설치 기준인 도로표지규칙의 일부 기준이 미흡하고 운영 및 관리담당 기관이 일원화되지 않아, 전문적 도로표지 관리가 용이하지 않은 실정이다. 이에 도로표지의 통합적 전문적 관리와, 그에 따른 도로표지의 신속하고 정확한 조사가 필요하게 되었다. 본 연구에서는 최적의 조사시스템을 도출하기 위하여 도로시설물의 조사를 위한 여러 방법과 시스템을 비교하고 그 장단점을 분석하였다. 또한, 수치지도를 바탕으로 한 도로망도를 추출하고 DGPS 측량을 실시한 도로망도를 이용하여 현지조사를 실시하였다. 현지 조사 시스템을 공간정보, 속성정보로 구성된 데이터베이스, 표지판등록 및 GPS프로그램으로 구성된 응용프로그램, 소프트웨어와 경로탐색용 네비게이션, 노트북, 디지털카메라, GPS로 구성된 하드웨어로 구성하여 현지조사에 사용하였다. 현지조사 작업은 차량에 설치된 디지털카메라를 이용하여 원격조정으로 도로표지의 사진을 촬영하고, GPS를 이용하여 위치를 측정하였다. 현지조사 시스템은 지도의 축척에 맞는 정확도로 조정이 가능하며, 도로표지 조사뿐만 아니라 교통표지 및 그 외의 도로시설물의 조사에도 활용하고, 무선통신을 이용한다면 실시간 정보의 수정 및 입력이 가능할 것으로 판단된다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.10
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• pp.1028-1039
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• 2014

After DTV transition, frequency allocation to efficiently utilize 700 MHz band, which is remained as Digital Dividend, is in progress domestically and internationally. This paper investigates global frequency allocation of 700 MHz band and utilization of the band, and analyzes domestic wireless technology methods and requested frequency bandwidth by use. In addition, the paper suggests what needs to be considered in case of building public integrated radio network that focuses on disaster and safety network; the integrated radio network also includes railway network and e-Navigation.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.9
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• pp.536-542
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• 2004

An architecture of direct digital frequency synthesizers (DDFS) is studied in this paper The Direct digital frequency synthesizers (DDFS) provide fast frequency switching with high spectral purity and are widely used in modern spread spectrum wireless communication systems. ROM-based DDFS uses a ROM lookup table to store the amplitude of a sine wave. In this paper, we suggest three new techniques to reduce the ROM size. One new technique uses more number of hierarchical levels in ROM structures. Another techniques use simple interpolation techniques combined with hierarchical ROM structures. A 12 bit sine wave is generated by using these techniques. Experimental results show that the new proposed techniques can reduce the required ROM size by up to 24%, when compared to that of a resent method[1].

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.5
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• pp.104-108
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• 2004

The most of the CDMA mobile communication depends on the GPS for the time synchronization. Then, we must prepare alternative system against the unusable GPS like a unexpectable accident or strategic purpose by the USA government. In this study, we have constructed ground test segment for the time synchronization system using the geostationary satellite. In addition. we have designed, manufactured and tested the transmitting and receiving board to receive 1 PPS signal from atomic clock for transmitting stored data in buffer to satellite modem and to produce 1 PPS signal from satellite modem for measuring time delay.

• Journal of the Korean Society for Railway
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• v.17 no.5
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• pp.349-354
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• 2014

Other foreign countries already apply ETCS LEVEL 2 in signaling systems. It provides added functions to control a train using wireless communication compared with ETCS LEVEL 1. Nowadays, the ETCS LEVEL 2 system is being applied on revenue services more and more frequently. Therefore, it is necessary to develop ETCS LEVEL 2 to apply in this country. The advanced technology of the ETCS LEVEL 2 system provides continuous control for train protection, and ATP function, by comparing discontinuous controls on ETCS LEVEL 1. ETCS LEVEL 2 is a better system model for improving passenger safety. This paper describes the design of an onboard speed profile for the ETCS LEVEL 2 system and it forecasts the future of ETCS.