• 산업기술연구
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• 제28권A호
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• pp.97-104
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• 2008

Recently, interests on positioning system for location-based services have been significantly increased. Many indoor environment systems using fingerprint scheme have been designed to take more accuracy of positioning, but they are inefficient in adapting to change of environments. In this paper, we focus on a client-based positioning system over WLAN for decreasing installation cost and adapting to change of environments. In the proposed system, APs with stable RSSI are selected as base APs independently for each reference point. Experimental results show that proposed system expands service area approximately 20% much than traditional systems using K-NN algorithm and needs only 20% modification process to fingerprint data compare with traditional systems whenever environment conditions are changed.

• Journal of Information Technology Applications and Management
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• 제13권4호
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• pp.57-70
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• 2006

Location Based Service (LBS) provides high-value added service to users and various works about IBS have been actively performed. The core technology or LBS is positioning of the users. In the field of positioning, outdoor positioning and indoor positioning are developed separately. We are proposing a design of an outdoor-indoor positioning system, implementing a prototype of the system, and verifying the usefulness of the system through experiments. Our experimental results shows that the average error of our system is 4.8 m in the case of out-door positioning and it is 3.3 m in the case of in-door positioning.

• 대한안전경영과학회지
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• 제13권1호
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• pp.107-114
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• 2011

Location-Based Service(LBS) is a service that provides a variety of convenience in life using location information that can be obtained by mobile communication network or satellite signal. In order to provide LBS precisely and efficiently, we need the location determination technology, platform technology and server technology. In this study, we studied on how we can reduce the error on location determination of objects such people and things. Fingerprint location determination method was applied to this study because it can be used at current wireless communication infrastructure and less influenced by a variety of noisy environment than other location determination methods. We converted the probability value to logarithmic scale value because using the sum of k probability values is not suitable to be applied to weight determination. In order to confirm the performance of suggested method, we developed location determination test program with Visual Basic 6.0 and performed the test. According to indoor and outdoor test results, the suggested stochastic method reduced the distance error by 17%, 18% and 9% respectively at indoor environment and 25%, 11% and 4% at outdoor environment compared with deterministic NN, kNN and kWNN fingerprint methods.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.83-88
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• 2006

Many applications in the area of location-based services and personal navigation require nowadays the location determination of a user not only in outdoor environment but also indoor. To locate a person or object in a building, systems that use either infrared, ultrasonic or radio signals, and visible light for optical tracking have been developed. The use of WiFi for location determination has the advantage that no transmitters or receivers have to be installed in the building like in the case of infrared and ultrasonic based location systems. WiFi positioning technology adopts IEEE802.11x standard, by observing the radio signals from access points installed inside a building. These access points can be found nowadays in our daily environment, e.g. in many office buildings, public spaces and in urban areas. The principle of operation of location determination using WiFi signals is based on the measurement of the signal strengths to the surrounding available access points at a mobile terminal (e.g. PDA, notebook PC). An estimate of the location of the terminal is then obtained on the basis of these measurements and a signal propagation model inside the building. The signal propagation model can be obtained using simulations or with prior calibration measurements at known locations in an offline phase. The most common location determination approach is based on signal propagation patterns, namely WiFi fingerprinting. In this paper the underlying technology is briefly reviewed followed by an investigation of two WiFi positioning systems. Testing of the system is performed in two localization test beds, one at the Vienna University of Technology and the second at the Hong Kong Polytechnic University. First test showed that the trajectory of a moving user could be obtained with a standard deviation of about ${\pm}$ 3 m.

• Journal of Information Technology Applications and Management
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• 제12권4호
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• pp.93-104
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• 2005

Recently, RFID/USN is one of fundamental technologies in information and communications networks. Low-Rate WPAN, IEEE802.15.4 is a low-cost communication network that allows wireless connectivity in applications with limited Power and relaxed throughput requirements. Its applications are building automation, personal healthcare, industrial control, consumer electronics, and so on. Some applications require location information. Of course location awareness is useful to improve usability of data Low-Rate WPAN Is regarded as a key specification of the sensor network with the characteristics of wireless communication, computing, energy scavenging, self-networking, and etc. Unfortunately ZigBee alliance propose a lot of applications based on location aware technologies, but the specification and low-rate WPAN devices don't support anything about location-based services. RSSI ( Received Signal Strength indication) is for energy detection to associate, channel selection, and etc. RSSI is used to find the location of a potable device in WLAN. In this paper we studied indoor location awareness using vector matching of RSSI in low-Rate wireless PAN. We analyzed the characteristics of RSSI according to distance and experimented location awareness. We implemented sensor nodes with different shapes and configured the sensor network for the location awareness with 4 fixed nodes and a mobile node. We try to contribute developing location awareness method using RSSI in 3-dimension space.

• 대한안전경영과학회지
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• 제20권2호
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• pp.9-20
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• 2018

This study is empirically intended to look into the effects of HVAC management on condensation cause and prevention in indoor swimming pools. The findings are summarized as follows. First, the experience of condensation in indoor swimming pools showed that 132 out of 142 people in total experienced the condensation in indoor swimming pools, which they had a high experience rate of 92.3%. For the location of condensation, the wall joints were 46.8% and the windows were 34.5%, which a total of 72.3% occurred in the wall joints and windows. Second, the effect of construction design, HVAC management and building construction on the cause of condensation in indoor swimming pools showed that building construction had an effect on the cause and location of condensation depending on the seasonal time, partially adopting hypothesis 1. Third, the effect of condensation-causing factors on condensation-preventing factors in indoor swimming pools showed that condensation had a close relationship with air and temperature conditions depending on the time and location of condensation, adopting hypothesis 2. As for the above-stated findings, the HVAC management in indoor swimming pools is an important concern factor that continues to cause condensation despite the development of advanced construction materials. Especially, building construction is a main factor that has a direct effect on condensation in the HVAC management of facilities. This implies that the window management is important in maintaining the wall joints - which can suppress the selective use and defect occurrence of construction materials - or confined spaces for a long time.

• 한국태양에너지학회 논문집
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• 제31권5호
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• pp.113-118
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• 2011

In order to prevent incoming solar radiation, it is necessary to study about blinds' blocking out effects of heat that are installed at the balcony at an apartment house. To figure out the heating effects from the windows, a study for indoor thermal environment according to the location of blinds is also needed. In order to find out the changes of indoor thermal environment, we'll compare models of a house building with or without Venetian blinds: one place has an extended living room removing a balcony and another one has a normal balcony. The result is as follows. Without blinds, the place with an extended living room has benefits for saving heat compare to the place with a normal balcony. It's because the warm air heated by the incoming solar radiation moves into the living room through convection current and radiation which causes an increase of the indoor temperature. At an extended living room, the temperature difference from outside and inside, when blinds were installed inside, was $1.9^{\circ}C$ while it was $0.6^{\circ}C$ when the blinds were installed at outside of the balcony. It is evaluated that setting up the blind outside prevents much heat. At the space with a normal balcony, installing blinds at living room windows can save much heat compare to installing blinds at windows at the balcony. The indoor temperature was low when blinds were installed. It can be said that blinds block heat from the incoming solar radiation. Moreover, when blinds are installed, there is a big change of indoor temperature due to the radiation from the blinds' slat and convective activities in between the blinds and windows. This also has to be considered.

• Journal of Advanced Marine Engineering and Technology
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• 제39권2호
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• pp.179-186
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• 2015

In the indoor location estimation system, which has recently been actively studied, the received signal strength indicator contains a high level of noise when measuring the signal strength in the range between two nodes consisting of a receiver and a transceiver. To minimize the noise level, this paper proposes an improved adaptive smoothing filter that provides different exponential weights to the current value and previous averaged one of the data that were obtained from the nodes, because the characteristic signal attenuation of the received signal strength indicator generally has a log distribution. The proposed method can effectively decrease the noise level by using a feedback filter that can provide different weights according to the noise level of the obtained data and thus increase the accuracy in the distance and location without an additional filter such as the link quality indicator, which can verify the communication quality state to decrease the range errors in the indoor location recognition using ZigBee based on IEEE 802.15.4. For verifying the performance of the proposed improved adaptive smoothing filter, actual experiments are conducted in three indoor locations of different spatial sections. From the experimental results, it is verified that the proposed technique is superior to other techniques in range measurement.

• 대한전자공학회논문지TC
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• 제42권1호`
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• pp.9-15
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• 2005

현재 위치결정기술에 주로 사용되고 있는 매체는 RF이다. 그러나 RF를 사용한 위치결정기술은 GPS나 실외의 LOS 상황에서 주로 이용되고 있다. 왜냐하면 실내에서는 다중경로 해상도가 좋지 않아 정확한 위치 값을 계산해 내기가 힘들기 때문이다. UWB는 다중경로 해상도가 높고 장애물 투과율이 좋은 실내 측위에 적합한 매체이며 현재 UWB 통신 및 위치측정에 사용하고자 하는 표준화가 IEEE 802.15 위원회에서 진행 중이다. 그러나 UWB를 이용한 실내 측위 알고리즘의 연구나 개발은 아직 미비하다. 본 논문에서는 실내 측위에서 UWB의 장점을 극대화 할 수 있는 TDOA 알고리즘 중 대표적인 두 가지 알고리즘을 분석하고 이를 UWB 실내 측위에 이용할 때 얼마나 정확한 위치를 추정할 수 있는지를 시뮬레이션을 통해 분석한다. 또한 UWB 채널모델을 분석하고 오차요소를 시뮬레이션에 적용하여 그 결과를 비교분석하며, 시뮬레이션 결과를 바탕으로 실내 측위를 위한 UWB의 가능성 및 적합한 알고리즘을 제안한다.

• 한국철도학회논문집
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• 제19권5호
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• pp.585-591
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• 2016

최근 IoT환경에서 다양한 위치기반의 서비스의 확산으로 인해 실내측위는 중요한 영역으로 자리잡고 있다. 이에 본 논문에서는 특정 공간에 시설물, 서비스 등을 고려한 가상의 영역을 Zone으로 설정하였고, 다층퍼셉트론(MLP: Multi-Layer Perceptron)을 사용하여 Zone을 인식하는 방법을 제안하였다. 제안방법의 다층퍼셉트론은 입력으로 BLE(Bluetooth Low Energy) Beacon의 RSSI(Received Signal Strength Indicator)신호를 입력으로 활용하였고 현재 위치의 소속된 Zone을 출력하였다. 제안방법의 검증을 위해서 실제 역사와 유사한 크기의 실험환경을 구축하였으며 4개의 Beacon을 설치하였고 2개의 Zone영역을 설정하였다.