• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6A
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• pp.476-483
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• 2009

Recently much attention has been devoted to femtocell's potential to improve indoor cellular coverage and high speed wireless communications. Femtocell based commercial services have been already launched in some countries and standardization activities are actively on-going, there has been concern however over potential issues of interference between femtocells and the micro/macro networks. With universal frequency reuse, the ensuing cross-tier interference causes unacceptable data rate and outage probability, so an analysis of effect of interference in femtocell embedded networks would be necessary for a stable system design. This paper investigates the effect of interference on system performances of femtocell embedded hierarchical cell structure (HCS) networks considering the characteristics of propagation environments. Various channel parameters are specially considered for indoor environments where most of femtocells are deployed to investigate the effect of interference of femtocell embedded RCS networks. System capacity and coverage are provided with variant distance between macrocell and femtocell, location of the user in femtocell coverage, and characteristic of building structures.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.2
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• pp.189-196
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• 2010

Spatial information and smart phone technology have made innovative improvement of daily life. Spatial and geographic information are in practice for various applications. Especially, spatial information along with information and telecommunication technology could create new contents for providing services for convenient daily life. Spatial information technology, recently, is not only for acquiring location and attribute data but also providing tools to extract information and knowledge systematically for decision making. Various indoor applications have emerged in accordance with demands on daily GIS(Geographic information system). This paper aims for applying spatial information technology to support decision-making in shopping. The main contents include product database, optimal path search, shopping time expectation, automatic housekeeping book generation and analysis. Especially for foods, function to analyze information of the nutrition facts could help to improve dietary pattern and well-being. In addition, this system is expected to provide information for preventing overconsumption and impulse purchase could help economical and effective purchase pattern by analyzing propensity to consume.

• Fire Science and Engineering
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• v.33 no.1
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• pp.92-98
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• 2019

To determine if water-jet nozzle moves and water jetting are effective according to the location of the fire, this study examined the automatic fire-tracking water cannon system and aan indoor hydrant system, such as water jet centered directivity, water jet range maintainability and water jet shape uniformity. First, an examination to find the center of fire accurately from this system design showed that the water jet centered test was accurate. Second, the water jet range test results showed that when water is jetted at the maximum water jet radius, the water jet shows an inaccurate result but within the allowable tolerance range. Finally, the water-jet shape test result confirmed that there are no problems in setting the block from the algorithm design.

• Journal of Intelligence and Information Systems
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• v.23 no.4
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• pp.1-31
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• 2017

Modern businesses are adopting new technologies to serve their markets better as well as to improve efficiency and productivity. The advertising industry has continuously experienced disruptions from the traditional channels (radio, television and print media) to new complex ones including internet, social media and mobile-based advertising. This case study focuses on proposing intelligent advertising business model in Seoul's metro network. Seoul has one of the world's busiest metro network and transports a huge number of travelers on a daily basis. The high number of travelers coupled with a well-planned metro network creates a platform where marketers can initiate engagement and interact with both customers and potential customers. In the current advertising model, advertising is on illuminated and framed posters in the stations and in-car, non-illuminated posters, and digital screens that show scheduled arrivals and departures of metros. Some stations have digital screens that show adverts but they do not have location capability. Most of the current advertising media have one key limitation: space. For posters whether illuminated or not, one space can host only one advert at a time. Empirical literatures show that there is room for improving this advertising model and eliminate the space limitation by replacing the poster adverts with digital advertising platform. This new model will not only be digital, but will also provide intelligent advertising platform that is driven by data. The digital platform will incorporate location sensing, e-commerce, and mobile platform to create new value to all stakeholders. Travel cards used in the metro will be registered and the card scanners will have a capability to capture traveler's data when travelers tap their cards. This data once analyzed will make it possible to identify different customer groups. Advertisers and marketers will then be able to target specific customer groups, customize adverts based on the targeted consumer group, and offer a wide variety of advertising formats. Format includes video, cinemagraphs, moving pictures, and animation. Different advert formats create different emotions in the customer's mind and the goal should be to use format or combination of formats that arouse the expected emotion and lead to an engagement. Combination of different formats will be more effective and this can only work in a digital platform. Adverts will be location based, ensuring that adverts will show more frequently when the metro is near the premises of an advertiser. The advertising platform will automatically detect the next station and screens inside the metro will prioritize adverts in the station where the metro will be stopping. In the mobile platform, customers who opt to receive notifications will receive them when they approach the business premises of advertiser. The mobile platform will have indoor navigation for the underground shopping malls that will allow customers to search for facilities within the mall, products they may want to buy as well as deals going on in the underground mall. To create an end-to-end solution, the mobile solution will have a capability to allow customers purchase products through their phones, get coupons for deals, and review products and shops where they have bought a product. The indoor navigation will host intelligent mobile-based advertisement and a recommendation system. The indoor navigation will have adverts such that when a customer is searching for information, the recommendation system shows adverts that are near the place traveler is searching or in the direction that the traveler is moving. These adverts will be linked to the e-commerce platform such that if a customer clicks on an advert, it leads them to the product description page. The whole system will have multi-language as well as text-to-speech capability such that both locals and tourists have no language barrier. The implications of implementing this model are varied including support for small and medium businesses operating in the underground malls, improved customer experience, new job opportunities, additional revenue to business model operator, and flexibility in advertising. The new value created will benefit all the stakeholders.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.1
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• pp.63-69
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• 2016

Although the previous information technologies had been used for the quick and accurate processing of work, At present, however, as the combination with the Internet, the IOT(Internet-of-Things) era in which the diverse pieces of information are collected and handled through the sensor networks is in progress. Among these application fields of the IoT, the indoors position identification technology has been developing in the direction of providing the position information in the buildings of which the lengths and the interiors are complicated and in the direction of providing the various pieces of information and others of the like to the nearby customers. In this paper, we proposed an indoors position identification system that detects the patrol positions of the prison officers in the correctional facilities and in the prisons by using the ultrasonic waves, that transmits these to the control system and the data gateway, and that transmits the detected data. The Indoors Positioning identification System is organized with the tags for recognizing the positions that transmit the ultrasonic signal, ultrasonic receiver and data gateway. And the indoors position information data were transmitted to the management system through the data gateway. We evaluated the transmission error, by changing the distance of the proposed system for location recognition tag and the receiver, As a result, we found out that, when the transmission distance was 10 cm or less, the errors occurred in the form of the distortions. And when it was 110 cm or more, the transmission errors occurred due to the propagation diminutions of the ultrasonic wave signals. And when the transmission distance was from 10 cm to 100 cm, it was shown that the proposed system was possible without any errors.

• Journal of the Korean Institute of Gas
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• v.25 no.3
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• pp.46-52
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• 2021

In this study, the on-site location identification and response system was proposed by accurately checking the location information of rescue requesters in the buildings using the smartphone Wi-Fi AP. The location server was requested to measure the strength of the Wi-Fi AP at least 25 times at 8 different building location points. And the accuracy of the position and the error range were checked by analyzing the coordinate values of the received positions. In addition, the response time was measured by changing the conditions of location information in three groups to compare the response time for saving lives with and without location information. The minimum and maximum error values for the eight cases were found to be at least 4.137 m and up to 14.037 m, respectively, with an average error of 9.525 m. Compared to the base transceiver station (BTS) based position error value of 263m, the range could be reduced by up to 93%. When the location information was given, it took 10 minutes and 50 seconds to save lives; however, when there was no location information at all, rescue process took more than 45 minutes. From this research effort, it was analyzed that the acquisition of the location information of rescuees in the building using the smartphone Wi-Fi AP approach is effective in reducing the life-saving time for on-site responses.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1309-1320
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• 2023

The technological development and popularization of mobile devices have developed so that users can check their location anywhere and use the Internet. However, in the case of indoors, the Internet can be used smoothly, but the global positioning system (GPS) function is difficult to use. There is an increasing need to provide real-time location information in shaded areas where GPS is not received, such as department stores, museums, conference halls, schools, and tunnels, which are indoor public places. Accordingly, research on the recent indoor positioning technology based on light detection and ranging (LiDAR) equipment is increasing to build a landmark database. Focusing on the accessibility of building a landmark database, this study attempted to develop a technique for estimating the user's location by using a single image taken of a landmark based on a mobile device and the landmark database information constructed in advance. First, a landmark database was constructed. In order to estimate the user's location only with the mobile image photographing the landmark, it is essential to detect the landmark from the mobile image, and to acquire the ground coordinates of the points with fixed characteristics from the detected landmark. In the second step, by applying the bag of words (BoW) image search technology, the landmark photographed by the mobile image among the landmark database was searched up to a similar 4th place. In the third step, one of the four candidate landmarks searched through the scale invariant feature transform (SIFT) feature point extraction technique and Homography random sample consensus(RANSAC) was selected, and at this time, filtering was performed once more based on the number of matching points through threshold setting. In the fourth step, the landmark image was projected onto the mobile image through the Homography matrix between the corresponding landmark and the mobile image to detect the area of the landmark and the corner. Finally, the user's location was estimated through the location estimation technique. As a result of analyzing the performance of the technology, the landmark search performance was measured to be about 86%. As a result of comparing the location estimation result with the user's actual ground coordinate, it was confirmed that it had a horizontal location accuracy of about 0.56 m, and it was confirmed that the user's location could be estimated with a mobile image by constructing a landmark database without separate expensive equipment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.2
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• pp.285-297
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• 2015

In this paper, Ulta-WideBand (UWB) channel measurement and modeling based on compressive sampling (CS) are proposed. The sparsity of the channel impulse response (CIR) of the UWB signal in frequency domain enables the proposed channel measurement to have a low-complexity and to provide a comparable performance compared with the existing approaches especially used for the indoor geo-localization purpose. Furthermore, to improve the performance under noisy situation, the soft thresholding method is also investigated in solving the optimization problem for signal recovery of CS. Via numerical results, the proposed channel measurement and modeling are evaluated with the real measured data in terms of location estimation error, bandwidth, and compression ratio for indoor geo-localization using UWB system.

• Journal of Advanced Navigation Technology
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• v.25 no.6
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• pp.441-449
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• 2021

With advances in autonomous vehicles, there is a growing demand for more accurate position estimation. Especially, this is a case for a moving robot for the indoor operation which necessitates the higher accuracy in position estimation when the robot is required to execute the task at a predestined location. Thus, a method for improving the position estimation which is applicable to both the fixed and the moving object is proposed. The proposed method exploits the initial position estimation from Bluetooth beacon signals as observation signals. Then, it estimates the gravitational acceleration applied to each axis in an inertial frame coordinate through computing roll and pitch angles and combining them with magnetometer measurements to compute yaw angle. Finally, it refines the control inputs for an object with motion dynamics by computing acceleration on each axis, which is used for improving the performance of Kalman filter. The experimental assessment of the proposed algorithm shows that it improves the position estimation accuracy in comparison to a conventional Kalman filter in terms of average error distance at both the fixed and moving states.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.3
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• pp.175-182
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• 2020

This paper introduces a study to estimate the user altitude in need of rescue in an emergency. The altitude is estimated by using the barometric pressure sensor embedded in the smartphone. Compared to GPS, which is degraded in urban or indoor environments, it has the advantage of not having spatial restrictions. With the endless development of smartphone hardware, it is possible to estimate the absolute altitude using the measured value if only the bias of the embedded barometric pressure sensor is applied. The altitude information of the person in need of rescue in an emergency is a great help in reducing rescue time. Since time is tight, we propose online calibration that provides the barometric pressure sensor bias used for altitude estimation through database. Furthermore, experiments were conducted to understand the characteristics of the barometric pressure sensor, which is greatly affected by wind. At the end, the altitude estimation performance was confirmed through an actual field tests in various floors in the building.