• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.325-331
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• 2017

As a GPS stability problem arises, MLAT system is spotlighted as an alternative technology of ADS-B. MLAT system has a high position accuracy as much as ADS-B. Also, MLAT receives the mode A,C,S, and 1090ES(ADS-B) signals from the mounted aircraft transponder. MLAT receives signals from several receiver units and calculates aircraft positions. MLAT has ADS-B level positioning accurarcy using GPS and can calculate the position information with objects independently. According to global environment changes, Local area multiltilateration(LAM) surveillance system is under development for moving vehicles and aircraft detection in airport. These are still under testing in Tae-an Airfield. In the paper, we analyzed the performance by comparing the calculated position data from MLAT to RTK. In order to confirm the position accuracy of MLAT and the deviation of position data between fixed target and moving target on the ground during the field test in Tae-an Airfield.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.8
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• pp.743-750
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• 2016

The conventional track to train communication is commonly using radio based equipment such as transponder or balise to transmit the data. However, there are some drawbacks of the conventional equipment, for example multipath fading, source of bandwidth limitation, and interference from other users. Moreover, the radio based equipment is very expensive when installed in large numbers. To address these problems, we propose infrared system for trackside to train communication system. Infrared system offers a transmission of data to train and it can be processed to obtain at least a train location. Infrared communication protocol provides practical wireless data communication for direct dedication configuration. Furthermore, on the pole configuration the infrared system provides an abundant bandwidth, an economically sensible, minimalized installation of equipment on the trackside and reliability for heavy rain environment. This paper concentrates on the communication function and measurement performance evaluation. The proposed trackside to train communication system covers about 6 meters between infrared receiver and infrared transmitter, whereas the half angle of the transmitter is set to $19.65^{\circ}$ and the receiver angle is $15^{\circ}$.

• Journal of Advanced Navigation Technology
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• v.21 no.2
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• pp.163-170
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• 2017

MLAT which is an independent cooperative surveillance system is applied to increase the positon resoultin of secondary survelliance radar. MLAT uses the hyperboic or hyperboloid position mesurement algorithm. Central processing unit of MLAT calculates target position using time difference of arrival (TDOA) which can be solved from time of arrival (TOA) information of each receivers (at least 4 receivers). To increase position resolution of MLAT which use TDOA, TOA which is transfer time from tranmitter to receiver shold be calculated with precision time resolution in receiver. This paper explained the MLAT system briefly and explained ATD which is one of means of calcuating pulse position. ATD is applied to solve the deviation of pulse position due to different amplitude of signals in mulitiple receivers. In this paper, to analysis the performance of ATD, the simulation result of LAS and CDS was compared with the simulation result of basic threshold method.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.2
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• pp.161-170
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• 2017

The balise is a device for the railroad signal control systems, which is installed between both rail. The balise sends fixed or variable data, named telegram, to the train with wireless method. The telegram includes the position information, the movable distance under the signal status, the gradient, the speed, the temporary speed limit, etc. This research is on a design of the DBPL encoder for the balise. Normally the DBPL encoder for the balise is with the ASIC or FPGA technology. In this research, the DBPL encoder is designed with commercial low power operable micro-controller. The firmware(logic level encode) and the SPI Bus function block(physical level output) of the micro-controller are used for the DBPL encode. Under the european standard, the required working speed of the DBPL encoder is 564.48Kbps. The DBPL encoder of this research is tested under the speed of 564.48Kbps, and it worked properly.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.6
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• pp.10-15
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• 2008

In this paper, a new NMOS gate cross-connected current-mirror type bridge rectifier for UHF RFID applications is presented. The DC converting characteristics of the proposed rectifier are analyzed with the high frequency equivalent circuit and the gate capacitance reduction technique for reducing the gate leakage current due to the increasing of operating frequency is also proposed theoretically by circuitry method. As the results, the proposed rectifier shows nearly same DC output voltages as the existing NMOS gate cross-connected rectifier, but it shows the gate leakage current reduced to less than 1/4 and the power consumption reduced more than 30% at the load resistor, and it shows more stable DC supply voltages for the valiance of load resistance. In addition, the proposed rectifier shows high enough and well-rectified DC voltages for the frequency range of 13.56MHz HF(for ISO 18000-3), 915MHz UHF(for ISO 18000-6), and 2.45 GHz microwave(for ISO 18000-4). Therefore, the proposed rectifier can be used as a general purpose one to drive RFID transponder chips on various RFID systems which use specified frequencies.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.747-754
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• 2013

This paper proposed a new transponder detection method to reduce tag recognition time and simplify anti-collision process in RFID systems. In conventional systems, a transponder in detectable area is passively recognized by responding to a reader command. In addition, if there are multiple tags in the area, a collision between tags occurs by responding at the same time to a command and anti-collision process begins. In the proposed method, tags are actively recognized without any command from a reader which results to reducing a tag recognition time and simplifying anti-collision process. To compare transponder recognition time, the process of transponder recognition in conventional systems is analysed. A circuit to detect transponder directly is developed and antenna voltage variation of a reader in the appearance of multiple transponders is analysed for the implementation of the proposed method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1055-1059
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• 2004

A RFID(Radio Frequency Identification) system is a kind of radio frequency communication system and a branch of automatic data collection system. RFID system consists of RFID tags(or transponders) and RFID readers(controllers). This paper deals with the wireless communication that acquires tag IDs through RFID readers, and show the implementation of the target system which transmits tag IDs and related information to the server on the Internet through the wireless local area network. Today's RFID systems are usually implemented with the wired communication environment. In this paper, however, RFID system is effectively realized with the widely deployed wireless local area network and various RFID data can be collected by the readers which are communicating with the wireless access points of the local area network. Through the Internet, users also can have easy access to the server on the web and retrieve, analyze, and utilize tags' information.

• Korean Journal of Agricultural Science
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• v.22 no.1
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• pp.24-41
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• 1995

The objective of this study were to review and analyze the application technologies of electronics and microprocessor for environment control and automated management systems of livestock production of the advanced countries, and to select the appropriate and applicable technologies for our systems among the analyzed. In this study, the environment control systems were analyzed mainly on the poultry production systems; and the automated management systems on swine and dairy production systems. According to the results, the advanced technologies reviewed and analyzed could be applicable for designing our animal production systems, if those were modified and remodeled for our situation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.41-44
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• 2004

A RFID(Radio Frequency IDentification) system Is a kind of Radio Frequency Communication System and a branch of Automatic Data Collection System. The RFID System is composed of RF Tag(or Transponder) and RFID Reader(controller). This paper deal with Wireless communications that acquired RF Tag ID by RFID reader, and then target system will transmit Tag ID to RFID Server through the internet using Wireless LAN. The RFID system of Todays are commonly used by a wired RFID system. In this system uses commonly used Wireless LAN, and then we can connect the internet if we have a AP(Wireless Lan Access Point). Internet connection can make a transmission of RF Tag ID, and can make a reception of returning data that are images or information.

• 한국정보통신설비학회:학술대회논문집
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• 2002.08a
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• pp.135-136
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• 2002

테라비트급 WDM 광전송시스템은 채널당 10Gb/s의 전송속도를 갖는 채널을 파장분할다중하여 하나의 광섬유로 전송하는 시스템이다. 시스템의 주요 영역으로는 광을 송수신하는 광트랜스폰더, 다채널의 광신호를 다중/역다중 하는 광 다중화기/역다중화기, 광신호를 증폭하기 위한 광증폭기, 그리고 광분기 삽입기 등으로. 구성된다. 우리가 구성하는 테라비트급 WDM 광전송시스템은 구조 변경없이 TM 및 ADM 방식을 수용한다. 시스템의 신뢰성을 위해 종속망 절체 및 광학적 계층에서의 보호절체 방식으로 1+1 OCh 및 1+1 OMS 절체 기능을 선택적으로 수용할 수 있어 시스템 운영에 따라 효율적이고 경제적인 망 운영을 할 수 있다. 감시채널은 시스템 유지보수에 필요한 신호(PMI, FDI, BDI 등) 및 시스템 DCC용으로 되어 있으며, WDM 망에 적합한 감시 체계를 설계하였다.