• 한국환경과학회지
• /
• 제6권6호
• /
• pp.637-644
• /
• 1997

The purpose of thins study was to quantitatively determine the Indoor Infiltration of pollutants of outdoor origin. The relationship between Indoor and outdoor air is dependent, to a large extent. on the rate of k exchange between these two environments. Mean Indoor/outdoor ratios measured from thins study were: 0.70 for HNO3; 1.60 for HNO2: 0.56 far SOg: 1.30 for mf3: 0.96 for PM2.5(dP<2.5mm: 0.89 for SO4a': 0.87 for NO3· and 0.79 for NH4 'Mean Indoor concentrations for PMa s, SO4a., HNO9, NO3 and NIL' were similar to outdoor levels. Indoor HNO2 and mB3 values were h19her than outdoors. However, the Indoor level of SO2 was lower than ambient level.

• Physical Therapy Rehabilitation Science
• /
• 제10권3호
• /
• pp.356-366
• /
• 2021

Objective: This study aimed to compare gait ability through gait evaluations in indoor and outdoor environments according to the general characteristics and walking ability of stroke patients. Design: Crossed-sectional study. Methods: The subjects of this study were 57 hospitalized stroke patients.The study subjects were asked to select an indoor environment and an outdoor environment in random order, and the Timed Up and Go Test (TUG), 10-Meter Walk Test (10MWT), Figure-Eight Walk Test (F8WT) and the Functional Gait Assessment (FGA) were used to assess each environment. Results: The TUG, 10MWT, F8WT time and number of steps, and FGA showed a significant decrease in gait ability in the outdoor environment compared to the indoor environment (p<0.05). Although the TUG, 10MWT, and the time required for the F8WT were statistically higher in the outdoor compared to the indoor environment at points 2, 3, and 4, but not 5 of the functional ambulatory category (FAC), significant increases in the number of steps of the F8WT were found in the outdoor compared to the indoor environment for only points 2 and 3 of the FAC (p<0.05). In the FAC 3 and 4, there was a statistically significant decrease in the outdoor compared to the indoor environment only in the FGA (p<0.05). Conclusions: Therefore, it has been shown that the gait ability of stroke patients is reduced in the outdoor environment compared to the gait ability in the indoor environment.

• 산업기술연구
• /
• 제28권A호
• /
• pp.97-104
• /
• 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.

• ETRI Journal
• /
• 제40권4호
• /
• pp.458-470
• /
• 2018

This paper proposes a hierarchical roadmap (HRM) and its construction process to efficiently represent navigable areas in an indoor environment. HRM is adopted to solve the path-planning problems of mobile robots in indoor environments. HRM has a multi-layered graphical structure that enables it to abstract and cover navigable areas using a smaller number of nodes and edges than a probabilistic roadmap. During the incremental process of constructing HRM, information on navigable areas is abstracted using a sonar gridmap when the mobile robot navigates an unexplored area. The HRM-based planner efficiently searches for paths to answer queries by reducing the search space size using the multi-layered graphical structure. The benefits of the proposed HRM are experimentally verified in real indoor environments.

• 공학교육연구
• /
• 제13권5호
• /
• pp.76-80
• /
• 2010

In this paper, the Location Compensation Mechanism using equivalent distance rate ($LCM_{edr}$) for localization system based on SDS-TWR (Symmetric Double-Sided Two-Way Ranging) in wireless sensor network is proposed. The performance of the mechanism is experimented in terms of two types of the localization tracking scenarios of indoor and outdoor environments in university campus. From the experimentations, the compensation ratio in the $LCM_{edr}$ is better than that in SDS-TWR about 90% in indoor/outdoor environments in scenario 1 but also is better than that of SDS-TWR about 91.7% in indoor environment and about 100% in outdoor environment in scenario 2 respectively.

• 로봇학회논문지
• /
• 제4권4호
• /
• pp.305-311
• /
• 2009

FastSLAM is a factored solution to SLAM problem using a Rao-Blackwellized particle filter. In this paper, we propose a practical FastSLAM implementation method using an infrared camera for indoor environments. The infrared camera is equipped on a Pioneer3 robot and looks upward direction to the ceiling which has infrared tags with the same height. The infrared tags are detected with theinfrared camera as measurements, and the Nearest Neighbor method is used to solve the unknown data association problem. The global map is successfully built and the robot pose is predicted in real time by the FastSLAM2.0 algorithm. The experiment result shows the accuracy and robustness of the proposed method in practical indoor environment.

• Current Optics and Photonics
• /
• 제1권4호
• /
• pp.289-294
• /
• 2017

A high-performance time-division multiplexing (TDM) -based multiuser (MU) multiple-input multipleoutput (MIMO) system for efficient indoor visible-light communication (VLC) is presented. In this work, a MIMO technique based on RGB light-emitting diodes (LEDs) with selection combining (SC) is utilized for data transmission. That is, the proposed scheme employs RGB LEDs for parallel transmission of user data and transmits MU data in predefined slots of a time frame with a simple and efficient design, to schedule the transmission times for multiple users. Simulation results demonstrate that the proposed scheme offers an approximately 6 dB gain in signal-to-noise ratio (SNR) at a bit error rate (BER) of $3{\times}10^{-5}$, as compared to conventional MU single-input single-output (SISO) systems. Moreover, a data rate of 66.7 Mbps/user at a BER of $10^{-3}$ is achieved for 10 users in indoor VLC environments.

• ETRI Journal
• /
• 제41권6호
• /
• pp.739-749
• /
• 2019

Security and accuracy are two issues in the localization of wireless sensor networks (WSNs) that are difficult to balance in hostile indoor environments. Massive numbers of malicious positioning requests may cause the functional failure of an entire WSN. To eliminate the misjudgments caused by malicious nodes, we propose a compressive-sensing-based multiregional secure localization (CSMR_SL) algorithm to reduce the impact of malicious users on secure positioning by considering the resource-constrained nature of WSNs. In CSMR_SL, a multiregion offline mechanism is introduced to identify malicious nodes and a preprocessing procedure is adopted to weight and balance the contributions of anchor nodes. Simulation results show that CSMR_SL may significantly improve robustness against attacks and reduce the influence of indoor environments while maintaining sufficient accuracy levels.

• Journal of Communications and Networks
• /
• 제4권3호
• /
• pp.176-188
• /
• 2002

This paper presents results of continuous wave and swept frequency response measurements over the frequency range of UNII lower and middle bands from 5.15GHz to 5.35GHz in indoor environments. From the continuous wave measurements at 5.2GHz, the excess path loss, and the statistical characteristics of the temporal and spatial fading were found. By sweeping the frequency over the band, envelope correlation as a function of frequency was found and the coherence bandwidth (CBW) was determined from the envelope correlation. Using a channel model, the CBW was used to evaluate RMS delay spread. The dependence of CBW on the antenna polarization was simulated and compared with the measurement results. The influence of room size and separation of transmitter and receiver for LOS paths on RMS delay spread was discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권8호
• /
• pp.3965-3983
• /
• 2017

We propose a novel eye tracking method that can estimate 3D world coordinates using an infrared (IR) stereo camera for indoor and outdoor environments. This method first detects dark evidences such as eyes, eyebrows and mouths by fast multi-level thresholding. Among these evidences, eye pair evidences are detected by evidential reasoning and geometrical rules. For robust accuracy, two classifiers based on multiple layer perceptron (MLP) using gradient local binary patterns (GLBPs) verify whether the detected evidences are real eye pairs or not. Finally, the 3D world coordinates of detected eyes are calculated by region-based stereo matching. Compared with other eye detection methods, the proposed method can detect the eyes of people wearing sunglasses due to the use of the IR spectrum. Especially, when people are in dark environments such as driving at nighttime, driving in an indoor carpark, or passing through a tunnel, human eyes can be robustly detected because we use active IR illuminators. In the experimental results, it is shown that the proposed method can detect eye pairs with high performance in real-time under variable illumination conditions. Therefore, the proposed method can contribute to human-computer interactions (HCIs) and intelligent transportation systems (ITSs) applications such as gaze tracking, windshield head-up display and drowsiness detection.