• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.5
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• pp.156-170
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• 2019

Rapid increasing of smartphones has changed people's lifestyles, and location-based services are providing a platform to provide various conveniences in accordance with these changes. In particular, it may provide convenience to many users if location-based services are provided in an indoor area such as subway station. However, it is still a difficult task to ensure accurate positioning result for guiding routes in subway stations. This study proposes a KAI-R system that allows all processes to be performed in one system for indoor navigation in subway stations. The proposed system includes a new pedestrian step detection method for continuous positioning along with an improved fusion positioning algorithm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.12
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• pp.97-104
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• 2008

Location-based services provide customized information or services according to the user's location. The existing localization schemes for outdoor environment are not applicable to the indoor localization system which requires higher accuracy of location estimation than that of the outdoor localization system. In this paper, we employ the received signal strength(RSS) to approximate the distance between a moving target and a reference point and use the triangulation method to estimate the location of the moving target for the indoor localization system in IEEE 802.15.4 wireless PAN(personal area network). For the indoor localization system, we propose a scheme which selects the best reference points to enhance the localization accuracy and adaptively reflects the changes in propagation environments of a moving target to the distance approximation. Through the implementation of the localization system, we have verified the performance of the proposed scheme in terms of the estimation accuracy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.298-300
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• 2015

Beacon is a signal device, which mainly used to support the safety of the locate and operation of a watercraft and aircraft. Recently, the IT sector BLE (Bluetooth Low Energy) also made possible to operate with less energy over several months using a beacon standards are applied. In addition, the location-based services and technologies using BLE Beacon has attracted attention. However, there is the problem that by using only the position location Beacon devices when high error rate can be measured accurate position. Therefore, in this paper, combines WiFi and Beacon based on Smartphone. Also propose an indoor positioning algorithm reduces the error rate of the position location value.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.72-78
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• 2011

Localization information of an object can be a very useful element for many application areas. Presently, GPS is typically used for it, but many researches on the wireless localization technology are going on recently actively using mobile communication network, wireless sensor network, and ad hoc network in order to overcome the limitations of the GPS such as indoor, cost, power consumption, and etc. Therefore, this article surveys the most representative wireless localization techniques, which can be deployed in the wireless networks, and their principles and performances are analyzed based on the researched papers. In a conclusion, selection of a localization technique should consider the key design elements to a given application from the design elements such as localization environment, accuracy, time to fix, computation amount, implementation ease, and etc.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1643-1654
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• 2015

With standardization of IEEE 802.11n, APs with the 2.4GHz and 5GHz dual-band capability have widely been deployed over a metropolitan area by individuals and internet service providers. Moreover, due to the increasing attentions on indoor-localization technique using Wi-Fi, the need for LOS and NLOS determination scheme is increasing to enhance accuracy of the localization. In this paper, we propose a novel LOS/NLOS determination technique by using different radio attenuation characteristics in different frequency bands and different mediums. Based on this technique, we designed a LOS/NLOS-aware indoor localization scheme. The proposed LOS/NLOS determination algorithm can be used when the distance between an user device and an AP is unknown, and the proposed localization scheme provides very accurate room-level position information. We validated the proposed scheme by implementing it on Android smart phones.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.9
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• pp.369-376
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• 2017

Recently, an RSSI-based fingerprinting localization technology has been widely used in indoor location-based services. In the conventional fingerprinting method, as many APs as possible are used to increase the accuracy of location estimation. In another study, a part of APs having the strongest RSSI signal intensity are selected and used to reduce the time spent for positioning. However, it does not reflect the influence of RSSI occurred from the changes of the surrounding environments such as human movement or moving obstacles in a real environment. The environmental changes may cause the difference between the predicted RSSI signal strength value and the measured value, and thus occur an unpredictable error in the position estimation. Therefore, in order to mitigate the error caused by environmental factors, it is necessary to select APs suitable for indoor positioning estimation considering the changes in the surrounding environments. In this paper, we propose a method to select stable APs considering the influence of surrounding environments and derive a suitable positioning algorithm. In addition, we compare and analyze the performance of the proposed method with that of the existing AP selection methods through experiments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.3
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• pp.117-123
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• 2022

Unlike the satellite-based outdoor positioning system, the indoor positioning system utilizes various wireless technologies such as BLE, Wi-Fi, and UWB. BLE-based beacon technology can measure the user's location by periodically broadcasting predefined device ID and location information and using RSSI from the receiving device. Existing BLE-based indoor positioning system studies have many studies comparing the error between the user's actual location and the estimated location at a single point. In this paper, we propose a technique to evaluate the positioning accuracy according to the movement path or area by applying the entropy analysis model. In addition, simulation results show that calculated entropy results for different paths can be compared to assess which path is more accurate.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.602-605
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• 2011

현재 측위에 대한 측정 대상이 점점 작아지면서, 그에 따른 정확도 까지 높아지고 있다. 실내 측위에 관한 기술은 대표적으로 단말기의 수신신호의 세기방식인 RSS(Received Signal Strength), 수신신호의 도달시간 방식 TOA(Time of Arrival), 수신 신호의 도달 시간차 방식 TDOA(Time Difference of Arrival), 수신신호의 입사각 방식인 AOA(Angle of Arrival) 등 여러 가지 기술이 활발히 진행되고 있다. 본 논문은 특수 장비를 사용하지 않고, 무선 네트워크 기반의 실내 측위 중에 정확도가 높은 Fingerprinting 방법을 택하였다. WLAN 기반 실내측위에 가장 많이 사용되는 KNN은 k개의 이웃수와 RP의 수에 따라 민감하다. 본 논문에서는 KNN 성능을 향상 시키기 위해 SVM 이용하여 SNR 데이터를 군집화를 적용한 KNN과 SVM을 혼합한 알고리즘을 제안하였다. 제안한 알고리즘은 신호잡음비 데이터를 KNN 방법에 적용하여 k개의 RP를 선택한 후 선택된 RP의 신호잡음비를 SVM에 적용하여 k개의 RP를 군집하여 분류한다. 실험 결과 위치 오차가 2m이내에 KNN/SVM 혼합 알고리즘이 KNN 알고리즘보다 성능이 우수하다.

• Information and Communications Magazine
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• v.25 no.12
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• pp.19-25
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• 2008

유비쿼터스 홈, 인명 방재, 지능형 로봇 등에 응용하기 위한 IEEE 802.15.4a 시스템은 실내에서 1m 이하의 측위 기능, 수Kbps ${\sim}$ 수Mbps의 통신 기능, 4개 이상의 SOP (Simultaneous Operating Pico-net), 30m이상의 통신거리 및 저전력을 요구한다. 이러한 표준을 수용하는 정밀측위 기능과 통신기능을 동시에 가지는 임펄스UWB SoC설계, 제작 및 시험기술에 대해서 언급하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.6
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• pp.1370-1374
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• 2013

The suitcase can follow its owner all on its own via the Bluetooth connectivity in your phone. A robotic vacuum cleaner than can understand voice commands and even follow homeowner. Robots are used in a variety of applications such as a robot wheelchair. In this paper, I focus the problem of automatic return to the base in the process of developing the moving robot for loading things. In this paper, I propose the indoor localization method which is able to determine the position of the robot in the building by using image processing techniques.