• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.47-48
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• 2022

The positioning technology that measures the position of a person or object is a key technology to deal with the location of the real coordinate system or converge the real and virtual worlds, such as digital twins, augmented reality, virtual reality, and autonomous driving. In estimating the location of a person or object at an indoor construction site, there are restrictions that it is impossible to receive location information from the outside, the communication infrastructure is insufficient, and it is difficult to install additional devices. Therefore, this study tested the direct sparse odometry algorithm, one of the visual Simultaneous Localization and Mapping (vSLAM) that estimate the current location and surrounding map using only image information, at an indoor construction site and analyzed its applicability as an indoor positioning technology. As a result, it was found that it is possible to properly estimate the surrounding map and the current location even in the indoor construction site, which has relatively few feature points. The results of this study can be used as reference data for researchers related to indoor positioning technology for construction sites in the future.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.93-94
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• 2022

Although various studies about indoor positioning systems, such as beacon and Wifi, have been conducting for indoor positioning of workers at construction sites, these systems have limitations in terms of accuracy or economics. To overcome these limitations, geomagnetic field sequence-based indoor positioning technology can be a good alternative. However, it is necessary to correct the geomagnetic field near the construction material stocking area since the geomagnetic field can be distorted near construction materials such as rebars. Therefore, this study conducted an experiment for identifying correction range of geomagnetic field near the construction material stocking area. It was analyzed that the geomagnetic field should be corrected up to 60cm in the horizontal direction from the stocking point if the height of stocking area for rebars is 40cm or more. This study can be used for important reference for development of geomagnetic field sequence-based indoor positioning technology suitable for construction sites.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.213-214
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• 2023

Positioning information of workers is important for safety management at construction sites. Among the various indoor positioning technologies, geomagnetic fields-based technology is more economical and has less error than other technologies. However, there is a problem that the installation and dismantling of materials such as formwork at construction sites can cause degradation in positioning performance. Therefore, in this study, the distortion of the geomagnetic field near euro-form was quantitatively measured and the application method of geomagnetic field-based indoor positioning technology on formwork stage was presented. The results showed that the distortion occurred within 10cm of the wall and column form, but positioning accuracy could be affected up to 60cm from the form due to the characteristic of geomagnetic field-collecting technology. Therefore, applying this technology to the formwork stage requires complementary measures, such as using other positioning techniques up to 60 cm near the formwork, or excluding distorted area when positioning. It is expected that this study can contribute to the efficient safety management of workers by suggesting ways to prevent an increase in positioning error when applying geomagnetic field sequence-based indoor positioning technology during the formwork stage.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.25-31
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• 2017

The indoor location based service proposed in the study was assigned to target a moving user. Positioning in the outdoor environment is accurate while using GPS. However, in an indoor environment, positioning is inaccurate and difficult. In order to overcome this, studies of various techniques for positioning based on wireless communication such as Wi-Fi, Zigbee and Bluetooth are being performed. The RSSI value and the delivery signal of the bluetooth beacon are measured according to the distance, and to a database. It was applied calculating the value for the average RSSI and the RSSI filtering feedback. Filtering is used to reduce the error of the RSSI values that are measured at long distance. When average and feedback filtering coefficient are set with 0.5, irregular and highly RSSI values are decreased. As the distance increases, the range of error is confirmed to have a reduction when using a distance calculation correction algorithm. Finally, when using the RSSI measurement results filtering, it corrects an unstable signal. Also, the distance correction algorithm is used to reduce a range of errors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1307-1312
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• 2015

The recent adoption of Bluetooth LE technology in smart phones triggered commercial interest in RSSI-based positioning technology. Estimation error in RSSI measurement due to the antenna pattern, multipath fading, environmental noise has to be considered for designing beacon systems. The paper proposes an analysis method and beacon planning rules for a small and isolated indoor service area, based on probabilistic model of RSSI estimation error. As an practically important guide, the beacons have to be installed at the boundary of the service area to minimize the maximum position error, whereas the beacons have to be evenly distributed in the service space to minimize the average estimation error.

• The Journal of Korean Institute of Next Generation Computing
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• v.14 no.6
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• pp.57-65
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• 2018

Conventional RF signal-based indoor localization techniques such as BLE or Wi-Fi based fingerprinting method show considerable localization errors even in small-scale indoor environments due to unstable received signal strength(RSS) of RF signals. Therefore, it is difficult to apply the existing RF-based fingerprinting techniques to large-scale indoor environments such as airports and department stores. In this paper, instead of RF signal we use the geomagnetic sensor signal for indoor localization, whose signal strength is more stable than RF RSS. Although similar geomagnetic field values exist in indoor space, an object movement would experience a unique sequence of the geomagnetic field signals as the movement continues. We use a deep neural network model called the recurrent neural network (RNN), which is effective in recognizing time-varying sequences of sensor data, to track the user's location and movement path. To evaluate the performance of the proposed geomagnetic field based indoor positioning system (IPS), we constructed a magnetic field map for a campus testbed of about $94m{\times}26$ dimension and trained RNN using various potential movement paths and their location data extracted from the magnetic field map. By adjusting various hyperparameters, we could achieve an average localization error of 1.20 meters in the testbed.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.1227-1230
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• 2005

최근 다양한 네트워크의 융합(Convergence) 추세에 따라 기존 PSTN 서비스도 인터넷에서 VoIP 형태로 제공이 되고 있다. 하지만 VoIP 서비스는 인터넷망을 이용하므로 부여된 발신번호 정보를 송출하지 않아 발신자의 위치 및 해당지역의 공공구조기관(PSAP)의 식별이 불가능하여 긴급서비스 지원을 위한 위치정보 제공을 못하는 문제점이 제기되었다. 최근 측위기술의 활용이 다양해지고 요구수준이 높아짐에 따라 실내에서의 신호 차폐 문제점을 극복할 수 있고, 높은 위치정확도 등을 제공하는 WLAN와 RFID 기술을 이용한 측위기술 연구가 활발하다. 따라서 본 논문에서는 Wi-Fi, RFID, GPS를 이용한 측위기술을 사용하여 무선이동통신 환경에서 VoIP 긴급서비스를 지원하기 위한 모델 제안과 각 구성요소에 대한 기능, 세부적인 지원 절차를 설명하고, 위치정보의 획득 및 처리를 위한 운용 시나리오에 관한 구체적 방안과 제안모델을 적용하기 위한 고려사항에 대한 분석결과를 제시한다. 그 결과 제안된 모델은 무선이동통신의 긴급서비스 설계시 적용이 기대된다.

• Spatial Information Research
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• v.23 no.1
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• pp.49-57
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• 2015

Due to high density of population and progress of high building construction technologies, the number of high buildings has been increasing. Several information services have been provided to figure out complex indoor structures of building such as indoor navigations and indoor map services. The most fundamental information for these services are indoor network information. Indoor network in building provides topological connectivity between spaces unlike geometric information of buildings. In order to make indoor network information, we have to edit network manually or derive network properties based on the geometric data of buildings. This process is not easy for complex buildings. In this paper, we suggest a method to generate indoor network automatically based on crowdsourcing. From the collected individual trajectories, we derive indoor network information with crowdsourcing. We validate our method with a sample set of trajectory data and the result shows that our method is practical if the indoor positioning technology is reasonably accurate.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.457-458
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• 2012

최근 무선으로 실내위치를 측정하는 방법으로 WiFi를 많이 사용하고 있다. WiFi를 이용하여 실내에서의 위치를 파악하는 것에서 끝나지 않고 이를 실시간으로 모니터링 함으로써 긴박한 인명구조의 상황이나 전시상황에서 사용하고자 한다. 기본 안드로이드 단말기(클라이언트)와 서버간의 통신에 의해서 클라이언트는 위치를 전송하고 서버는 이를 이용하여 실시간으로 현재위치를 파악 할 수 있도록 사용자에게 표시를 해준다. 향후 개발과정에서 실외위치 모니터링 기능까지 포함하도록 확장할 예정이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.482-484
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• 2015

대표적인 위치기반 기술인 GPS는 건물 내부와 같이 실내에서의 위치추정이 거의 불가능하다. 따라서 실내 측위의 방안으로 BlueTooth 4.0LE 기반의 장치인 비콘(Beacon)을 활용하여 실내 GPS의 역할을 수행하도록 하는 기법이 활용되고 있다. 그러나, 비콘의 거리측정에 사용되는 RSSI의 문제점으로 인해, 위치추정의 정확도가 급격히 저하되는 문제점을 가지고 있다. 본 논문에서는 개선된 위치선정 알고리즘을 통하여 오차율을 줄여, 정밀한 위치 추정이 가능한 알고리즘을 제안하였다.