• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2B
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• pp.99-106
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• 2009

The tracking information of objects or persons plays the important role for being advanced of the technology in the logistics management or processing. In this paper, we propose the TDOA-based localization method for port logistics environment for obtaining accurate location of a tag which is attached to some objects or persons. The proposed method consists of these modules for precision : An adaptive selection module of base reader, 2.5D locating method and position-restriction method using a map. This paper includes the performance evaluation of those methods. We could see the improved performance in the simulation. And we also implemented the system and achieved the accuracy of DRMS and CEP within 4 meters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.931-936
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• 2016

The PS algorithm divides the number of tags within the identification range of reader into smaller groups by increasing the transmission power incrementally and identifies them. It limits the number of responding tags by grouping the tags within the identification range of the reader, and thus can reduce the probability of tag collision. Also, in the PS algorithm, the reader takes advantages of the difference of identification ranges. This algorithm uses the fixed frame size at every scan. Therefore, it has problems that the performance can be shown variously according to the number of tags and frame size. In this paper, we propose an EPS algorithm that allocates the optimal frame size by estimating the number of tags at each scan, and apply it into the STAC protocol. The simulation results showed that STAC/EPS algorithm can improve the identification delay about 45% compared with STAC protocol. Also, it provides a stable identification delay regardless of power level increase.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1882-1883
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• 2007

본 논문은 근거리무선통신을 포함한 위치서비스를 위한 무선통신응용분야에 적용될 수 있는 고신뢰 고정밀 무선위치인식기술 방법을 제안한다. 제안된 위치인식방법은 양방향통신을 통해 추정된 무선태그의 신호세기 및 시간차를 측정된 거리정보를 바탕으로 상대적 위치에 대한 확률적 계산을 수행하게 되며, 측정데이터의 부정확성으로 인한 위치측정의 오차를 줄일 수 있다. 또한 제안된 고신뢰 무선측위 코아 스택을 근거리무선네트워크 형성이 가능한 2.4 GHz ISM 협대역 밴드의 ZigBee 무선비콘 및 무선태그 디바이스들에 탑재하고 실증시험을 위하여 스마트 홈 실내 환경 아래에서 $1m\;{\times}\;1m$ 의 위치인지를 가능케 하는 위치인식시스템을 구현한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7A
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• pp.654-661
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• 2011

RTLS (Real-time locating systems) are used for tracking the location of people or assets in real time. In this system, RTLS readers continuously communicate with RTLS tags for measuring time or ranges and location engine tries to calculate accurate location of tags. However, when we attempt to apply this system to real world, the non-line-of-sight(NLOS) problem can be critical to the system performance because of the obstacles. In this paper, we suggest a new location estimation method for an NLOS environment using a reader-selection strategy. We have implemented all components of the locating system and carried out experiments in a test-bed. The accuracy of the system is 50% better than that of the existing general locating system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.180-182
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• 2021

This paper proposes a method for estimating the location of a user using a beacon to provide a service in an indoor environment. To estimate the location using the beacon, a Gaussian filter was applied to the RSSI value of the beacon, and the distance conversion function was obtained through the filtered RSSI value to estimate the tag location by trilateration. Then, in the indoor space where the beacons are installed, the location estimation accuracy of 8 places where 3 beacons are at a certain distance was confirmed. As a result, it was possible to confirm the position estimation accuracy of ±0.097 standard deviation and 0.242 distance error.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1925-1933
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• 2015

RFID based applications that combine radar techniques to obtain the location and the ID of a tag have widely been investigated. In this paper, we analyze a recently proposed RFID system that can extract the tag IDs and their velocities using signals transmitted from the tag attached moving objects and verify its performance. In the proposed system, a beacon transmits triggering signal at regular intervals into a monitoring area and the tag receiving the triggering signal backscatters the FMCW(frequency modulation continuous wave) signal modulated by the tag ID. The reader system demodulates this FMCW signal using predefined two reference signals to obtain not only the tag ID but its velocity. In this paper, we show that the proposed system works properly and analyze the degree of performance degradation in cases when the synchronization error between the transmitting signal and the reference signal occurs, and even when sampling rate is lowered for implementation purpose. Finally, the analytical results are verified by simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12A
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• pp.966-974
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• 2011

In this paper, we propose an asset tracking system for applying a container port environment. If we attempt to apply this common locating system to a port environment for logistics automation, the system performance is degraded because there are many steel obstacles that cause interference in the RF communication and measurement. We divided readers into two types - fixed and mobile readers; hence, the location method operates in two steps for efficient wireless communication and precise measurement. In addition, the system estimates the location with trajectory information of assets when the small number of measurement is gathered. We implemented all the system components and installed these at a real port for evaluation. The success rate of communication and estimation is much better than that of the existing general locating system, and the location precision is substantially increased.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.9
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• pp.141-146
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• 2015

Recently, people are consuming more fermented food for its health benefits. When we think of fermented food, skate comes to mind. However, there are different preferences depending on the degree of fermentation. Thus, if there is a system that shows the degree of the fermentation on skate, people can eat according to their taste. This paper proposes a design of skate fermentation monitoring system for consumer taste using the smart RFID tag. The proposed system consists of the RFID tag, $NH_3$ sensor, reader, and server. In order to confirm the usefulness of the proposed system, we performed experiments on the skate fermentation. The proposed monitoring system can show the skate fermentation at 4 grades: None, Low, Medium, and Strong. With the smart RFID tag, we successfully estimated the skate fermentation.

• Journal of Digital Convergence
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• v.17 no.12
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• pp.211-217
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• 2019

Location positioning systems are available in applications such as mobile, robotic tracking systems and Wireless location-based service (LBS) applications. The GPS system is the most well-known location tracking system, but it is not easy to use indoors. The method of radio frequency identification (RFID) location tracking was studied in terms of cost-effectiveness for indoor location tracking systems. Most RFID systems use active RFID tags using expendable batteries, but in this paper, an inexpensive indoor location tracking system using passive RFID tags has been developed. A pattern matching method and a system for tracing location by generating regression curves were studied to use precision tracking algorithms. The system was tested by verifying the level of error caused by noise. The three-dimensional curves are produced by the regression equation estimated the statistically meaningful coordinates by the differential equation. The proposed system could also be applied to mobile robot systems, AGVs and mobile phone LBSs.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.9
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• pp.1027-1032
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• 2015

Using the radio wave, RFID(: Radio Frequency IDentification) wirelessly transmits the unique information saved in a tag attached on the specific object. In the construction area, the trend in using RFID for managing the input and inventory of the construction materials is upward. General management systems for the construction materials have only a function of identifying the tag attached on the construction materials, but the management system with a function of identifying and managing the location information of the construction materials employing RFID, for reusing it, is not actively developed. For the efficient reuse of the construction materials, in this paper, we propose the RFID system with a function of estimating and saving the location information of the specific construction materials, based on the estimated distances between the particular subs and reader. The proposed system consists of RFID reader, distance estimate, communication, and memory units.