• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권3호
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• pp.243-257
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• 2010

Rapid developments in wireless sensor networks have extended many applications, hence, many studies have developed wireless sensor network positioning systems for indoor environments. Among those systems, the Global Position System (GPS) is unsuitable for indoor environments due to Line-Of-Sight (LOS) limitations, while the wireless sensor network is more suitable, given its advantages of low cost, easy installation, and low energy consumption. Due to the complex settings of indoor environments and the high demands for precision, the implementation of an indoor positioning system is difficult to construct. This study adopts a low-cost positioning method that does not require additional hardware, and uses the received signal strength (RSS) values from the receiver node to estimate the distance between the test objects. Since many objects in indoor environments would attenuate the radio signals and cause errors in estimation distances, knowing the path loss exponent (PLE) in an environment is crucial. However, most studies preset a fixed PLE, and then substitute it into a radio propagation loss model to estimate the distance between the test points; such method would lead to serious errors. To address this problem, this study proposes a Path Loss Exponent Estimation Algorithm, which uses only four beacon nodes to construct a radio propagation loss model for an indoor environment, and is able to provide enhanced positioning precision, accurate positioning services, low cost, and high efficiency.

• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.537-542
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• 2016

The demand for LBS (Location Based Services) is increasing in the development of communication and mobile technologies. Positioning technology is a core technology for LBS, because LBS is based on a position of each device or user. But positioning technology especially for indoor environments is getting a lot of attention. Indoor positioning errors usually occur seriously in indoor environments where APs (Access Points) are set in a very concentrated and complex arrangement. In order to reduce indoor positioning errors, we adopt DOP (Dilution of Precision) which reflects an APs configuration information. In this paper, we propose an enhanced indoor positioning method using IEEE 802.11 RSSI measurements and AP configuration information.

• 한국실내디자인학회논문집
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• 제27권2호
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• pp.166-174
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• 2018

This study examined the indoor exercise environment use and needs of older adults. The target population was seniors aged 60 years and older living in a newly developed apartment complex. Variables include demographic and housing characteristics, status of exercise, and indoor exercise environmental evaluation and needs. A total of 102 data items were analyzed using frequency, t-test and ANOVA. Noteworthy results are as below. First, community centers and community welfare centers were the most desirable exercise environments because of affordability, exercise programs/spaces. Such exercise environments should be developed in more locations for increasing numbers of seniors. Second, indoor exercise environments need to be improved based on seniors' physical capabilities and environmental behavior. Third, supportive spaces such as restrooms, shower rooms, locker rooms should be carefully designed. Fourth, seniors wanted to have walking trails and indoor swimming pools, the most desirable exercise spaces, within ten to 15 minutes walking distance.

• Journal of Communications and Networks
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• 제16권3호
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• pp.335-343
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• 2014

This paper considers the crucial problem of deploying wireless relays for achieving a connected wireless sensor network in indoor environments, an important aspect related to the management of the sensor network. Several algorithms have been proposed for ensuring full sensing coverage and network connectivity. These algorithms are not applicable to indoor environments because of the complexity of indoor environments, in which a radio signal can be dramatically degraded by obstacles such as walls. We first prove theoretically that the indoor relay placement problem is NP-hard. We then predict the radio coverage of a given relay deployment in indoor environments. We consider two practical scenarios; wire-connected relays and radio-connected relays. For the network with wire-connected relays, we propose an efficient greedy algorithm to compute the deployment locations of relays for achieving the required coverage percentage. This algorithm is proved to provide a $H_n$ factor approximation to the theoretical optimum, where $H_n=1+{\frac{1}{2}}+{\cdots}+{\frac{1}{n}}={\ln}(n)+1$, and n is the number of all grid points. In the network with radio-connected relays, relays have to be connected in an ad hoc mode. We then propose an algorithm based on the previous algorithm for ensuring the connectivity of relays. Experimental results demonstrate that the proposed algorithms achieve better performance than baseline algorithms.

• 한국인터넷방송통신학회논문지
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• 제14권1호
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• pp.113-118
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• 2014

최근 실내 환경에서 온도, 습도 등과 같은 현상 데이터를 수집하여 제공하는 실내 상황 정보에 대한 연구가 진행되고 있다. 특히 빌딩에서 불쾌한 상황이 증가하고, 환경 변화에 대한 인식 요구가 증가하고 있다. 본 논문에서는 현상 데이터를 대신하여 실시간 실내 쾌적 상황 정보를 제공하기 위해 GIS 기반의 실내 쾌적 지수 및 상황 산출 엔진을 설계하고 구현한다. 이를 통해 자신의 실내 쾌적 상황을 자가 진단하고, 이를 사용자에게 알려주어 실내 환경을 관리할 수 있다.

• 한국환경과학회지
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• 제6권5호
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• pp.451-459
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• 1997

This paper alms to describe the indoor-outdoor air quality in school environment through the analyses of heavy metal concentration by inductively Coupled Plasma(ICPI, which were observed at some school environment, such as traffic area, industrial area seme-industrial area, and residence area. The results are as follows : (1) Regardless Indoor and outdoor, the area with the highest concentration of heavy metal is industrial area followed by traffic area, residence area and semi-industrial area in descending order of magnitude. And the heavy metal concentration of indoor is higher than that of outdoor. (2) The main heavy metal components with more high level concentration of Indoor than those of outdoor are Zn, Al, Ca and these heavy metal concentrations are higher in class than In corridor and outdoor.

• 한국공간구조학회논문집
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• 제8권1호
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• pp.77-88
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• 2008

본 연구에서는 대공간을 동계 및 하계로 구분하여 실내온열환경의 변화를 실측하고 냉 난방조건과 관련하여 대공간에서 형성되는 실내온열환경의 특성을 파악하는 것을 목적으로 하여, 대공간의 수직 및 수평온도분포, 객석온도분포, 실내표면온도분포, 실내온열쾌적성 등의 실내온열환경을 검토하였다.

• Journal of Information Processing Systems
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• 제13권6호
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• pp.1640-1651
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• 2017

To make an unmanned aerial vehicle (UAVs) fly in indoor environments, the indoor locations of the UAV are required. One of the approaches to calculate the locations of an UAV in indoor environments is enhanced trilateration using one Bluetooth-based beacon and three or more access points (APs). However, the locations of the UAV calculated by the common chord-based trilateration has errors due to the distance errors of the beacon measured at the multiple APs. This paper proposes a method that corrects the errors that occur in the process of applying the common chord-based trilateration to calculate the locations of an UAV. In the experiments, the results of measuring the locations using the proposed method in an indoor environment was compared and verified against the result of measuring the locations using the common chord-based trilateration. The proposed method improved the accuracy of location measurement by 81.2% compared to the common chord-based trilateration.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.865-868
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• 1999

In this paper, indoor propagation characteristics are analyzed for various environments such as corridors, walls and corners. In order to present the statistical model for indoor environments the loss factors of each case are obtained by linear regression analysis method with the function of logarithmic distance between transmitter and receiver.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권1호
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• pp.108-118
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• 2009

In this paper we develop an indoor location tracking system and its 3D tracking monitoring viewer, viz., 3D Navigation Viewer (3DNV). We focus on the integration of an indoor location tracking system with the Virtual Reality Modeling Language (VRML), to facilitate a representation of the user's spatial information in virtual indoor environments that is synchronized with the physical location environment. The developed indoor location tracking system employs beacons as active transmitters, and a listener as a passive receiver. The distance information calculated from the difference speeds of RF and Ultrasonic signals is exploited, to determine the user's physical location. This is essential in supporting third parties like doctors and caregivers in identifying the activities and status of a particular individual via 3DNV. 3DNV serves as a unified user interface for an indoor location tracking system, showing the viewpoint and position of the target in virtual indoor environments. It was implemented using VRML, to provide an actual real time visualization of the target's spatial information.