• Journal of Navigation and Port Research
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• v.31 no.10
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• pp.859-864
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• 2007

In the future, it is necessary that using the Satellite-based radio navigation augmentation system such as Differential Global Positioning System(DGPS) to achieve a position accuracy of sub-meter level in port. Generally, the receiver for DGPS reference station should meet performance specifications of RSIM Ver. 1.1 presented by RTCM. This paper proposes a method to verify performance of the receiver for DGPS reference station according to the RSIM Ver. 1.1. And this paper presented that performance evaluation of the commercial receiver for DGPS reference station through the proposed method is satisfied with RSIM Ver. 1.1.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.3 no.2
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• pp.11-17
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• 2004

In this paper we propose a new conceptual system for a network clock in which all node clocks are simultaneously synchronized to the national standard by intermediation parameter of satellite time. Experiments have shown the possibility of its adoption by real networks. The new proposed method has various structural benefits, in particular all node clocks can be kept at the same hierarchical quality in contrast to the existing method. The measurement results show that the accuracy of the experimental slave clock system can be kept within a few parts In 1012 and the MTIE (Maximum Time Interval Error) sufficiently meets ITU-T G.811 for the primary reference clock. A prototype system with fully automatic operational functions has been realized at present and is expected to be directly used for communication network synchronization in the near future.

• Annual Conference of KIPS
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• 2015.10a
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• pp.362-365
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• 2015

우리나라는 현재 코엑스, 백화점 같은 대형 건물들이 늘어나고 있다. 대형 건물은 실내 구조가 복잡해서 방문하는 사람들이 원하는 길을 찾기 어렵다. 기존 실외에서 길을 찾아주는 네비게이션의 발달은 단말기와 스마트폰의 발달과 함께 성장하였고, 모든 사람들이 사용할 수 있는 대중적인 서비스다. 하지만 기존 네비게이션에 위치 측정 방법인 위성 GPS신호는 실내에서는 사용이 불가해 실내 위치 측정을 위해 Wi-Fi, Beacon, Magnetic Field등 다른 기술을 사용하여 실내 위치 측정을 해야 한다. 그중에서도 이미 설치되어 있는 것을 사용하기 위해 Wi-Fi의 신호 값인 RSS값을 활용하였고, 일정하지 앉은 RSS값을 Kalman Filter와 EH Filter로 보정하여 정확한 실내 위치 측정이 된다는 것을 실험을 통해 보였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.47-49
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• 2022

IPS is an indoor positioning system that replaces GPS, which is less accurate due to walls and roofs inside buildings. Radio signals such as Wi-Fi are used instead of satellite signals, and complex methods are being used to increase accuracy. In this paper, we present a more efficient positioning method than before by applying high-level signals to high-accuracy fingerprint techniques. A radio map is configured with high-level signals collected by utilizing Wi-Fi APs, which are more than in the past. The suitability of use was confirmed by analyzing the pattern represented by the configured radio map for each location.

• Annual Conference of KIPS
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• 2011.11a
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• pp.691-694
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• 2011

차량의 위치를 인식하기 위한 시스템으로는 위성 위치 확인 시스템(GPS, Global Positioning System)과 관성 항법 시스템(INS, Inertial Navigation System)이 있다. INS는 차량의 최초 위치를 입력해야한다는 점과 시간이 지남에 따라 오차가 누적된다는 점 때문에 GPS와 INS가 상호보완적인요소로 통합하여 사용되고 있다. 하지만 GPS로부터 얻는 위치 정보는 정확성의 문제가 존재한다. 본 논문에서는 이를 해결하기 위해 톨게이트와 전광판을 활용하여 초기의 위치 값을 얻고, 누적오차를 방지하기 위해 재 초기화하는 방안을 제안한다. 고속도로상의 톨게이트와 전광판에는 모두 DSRC(Dedicate Short Range Communication) 시스템을 통해 위치를 전송할 수 있다. 따라서 INS의 최초 위치 입력이 필요한 문제와 누적오차 문제를 해결할 수 있다. 제안 방식을 통해 INS의 장점을 살리면서도 좀 더 정확한 위치를 인식 할 수 있어 차량 간 통신(V2V, Vehicle-to-Vehicle)기반의 이웃 차량 위치인지 시스템에 대한 연구가 더 활발해질 것으로 기대된다.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.1
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• pp.103-110
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• 2024

In this paper, a test bed for real-time network Real-Time Kinematic (RTK) research was constructed using reference stations of the NGII. A group of candidate station networks was derived, including three stations in Seoul. The group consisted of four stations with a distance of less than 100 km between them. Among several candidates, a network composed of stations with short distances between them and demonstrating good data quality for all reference stations was selected as the test bed. After collecting real-time data in Radio Technical Committee for Maritime services (RTCM) format from the selected stations and conducting a noise analysis on measurements, mm-level carrier phase measurement noise was confirmed. Afterwards, the user set the reference station inside the test bed and analyzed the network RTK positioning performance of the MAC method using the GPS L1 frequency as post-processing. From the result of the analysis it was confirmed that the residual error for all users was within 10 cm after applying the correction. Additionally, after determining integer ambiguities through Least-squares AMBiguity Decorrelation Adjustment (LAMBDA), it was confirmed that the fix rate was 100%, and all ambiguities were resolved as true values.

• Journal of Digital Convergence
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• v.19 no.2
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• pp.221-230
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• 2021

The study attempts to suggest potential problem and solutions expected in the process of implementing KASS, which is currently under development to improve the domestic navigation safety system, and to summarize improvement effects of domestic navigation safety system anticipated by the implementation of KASS. Challenges expected in the process of implementing KASS exists in four aspects: emotional, technical, cost, safety aspects. When KASS is implemented and operates, various benefits can be realized. Benefits include cost savings by not using navigation safety systems during takeoff and landing; reduction of flight delays and cancellations by removing airway congestion; increase of aircraft accommodation capacity; reduction of carbon emissions; preparation for future aviation demands and improvement of air transportation safety; and reduction of flight accidents. In conclusion, it is expected to enter into an era of more intense competition due to increased aviation demands. In order to survive in this competitive environment, early introduction of KASS is indispensable. Analysis results of this study are expected to provide reference information for academic research in this area. A possible future research topic include a study predicting the changes in the navigation safety systems introduced by KASS and proposing practical and useful ways to respond the changes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.3
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• pp.278-287
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• 2013

Modern information technologies continue to provide industries with new and improved methods. With the rapid development of Machine to Machine (M2M) communication, a smart container supply chain management is formed based on high performance sensors, computer vision, Global Positioning System (GPS) satellites, and Globle System for Mobile (GSM) communication. Existing supply chain management has limitation to real time container tracking. This paper focuses on the studies and implementation of real time container chain management with the development of the container identification system and automatic alert system for interrupts and for normal periodical alerts. The concept and methods of smart container modeling are introduced together with the structure explained prior to the implementation of smart container tracking alert system. Firstly, the paper introduces the container code identification and recognition algorithm implemented in visual studio 2010 with Opencv (computer vision library) and Tesseract (OCR engine) for real time operation. Secondly it discusses the current automatic alert system provided for real time container tracking and the limitations of those systems. Finally the paper summarizes the challenges and the possibilities for the future work for real time container tracking solutions with the ubiquitous mobile and satellite network together with the high performance sensors and computer vision. All of those components combine to provide an excellent delivery of supply chain management with outstanding operation and security.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.9
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• pp.811-820
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• 2012

GNSS signal is vulnerable to jamming signal because of well-known signal structure and weak signal power. For these reasons, the need for analysis of jamming effects and anti-jamming techniques of is increasing. In this paper, a GNSS signal generator is designed which includes a radio wave propagation model for six kind of tactical environments and a body masking model for the reception environment of a vehicle. The radio wave propagation model for downtown, rural, forest, coastline, waste land and snow or ice area is designed using two-ray model. The body masking model is designed the effect which the antenna is affected by the reception environment of a vehicle and radiation pattern from a user configuration. The performance of generated signals from the GNSS signal generator considering reception environment of a vehicle is evaluated by a commercial GPS L1 receiver(NordNav) in normal and jamming environment. Also, the generated GNSS signal is compared to a commercial GPS L1 H/W based RF signal generator(STR4500). The results show that the designed GNSS signal generator in a normal environment compared to the same navigation performance. In jamming environment, it is shown that the body masking effect and GNSS signal acquisition and tracking loss in compliance with the jamming signal are precisely working in the reception environment of a vehicle.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.1
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• pp.111-116
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• 2017

We propose the compact circular polarized antenna. The radiation elements of the proposed antenna is designed using FR4 substrate with the size of $25mm{\times}3.2mm{\times}5mm$ and stand on four corners of the feed network substrate. The feeder network is designed on FR4 substrate with the size of $40mm{\times}40mm{\times}0.8mm$ and has four oupt signals with same magnitude and $90^{\circ}$ phase difference. The input impedances of the designed radiation elements and the output impedances of the feeder network are $100{\Omega}$. The designed antenna has the dimension of $40mm{\times}40mm{\times}5.8mm$ and the operated frequency band of 1.559 - 1.609 GHz. The fabricated antenna has RHCP radiation pattern and the measured results of axial ratio less than 3.5 dB and radiated gain more than 1.5 dBic. The fabricated antenna can apply to GLONASS and Beiodu systems as well as GPS system.