• Proceedings of the Korea Air Pollution Research Association Conference
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• 2010.04a
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• pp.448-450
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• 2010

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.5
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• pp.382-391
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• 2009

The aim of the study was to assess the levels in typical central borough of phthalate exposure by monitoring children's facilities (19 kindergartens and 21 elementary schools) and households (17 old apartments and 22 new apartments) via sampling indoor floor dust. A vacuum cleaner specifically prepared for sampling dust was attached to a filter of a vacuum cleaner dust collecting container. During the sample preparation process, containers made of glass were used and analysis was performed using GC-MSD. The mean concentration of DEHP was $412{\mu}g/g$, DnBP was $24{\mu}g/g$, and BBzP was $10{\mu}g/g$ dust. The indoor characteristics including floor, wall materials, years after construction, water leakage history for the past three years, and ventilation were also examined to categorize phthalate esters from the dust samples. From the flooring and wallpaper materials of kindergartens and elementary schools, DEHP in the dust sample appeared at a statistically significant level (p<0.05) when PVC materials were present. DEHP in the indoor dust also increased significantly (p<0.01) during the construction period. The daily intake of DEHP measured from indoor dust was 0.08~$19.7{\mu}g/kg/day$ for children and 0.02~$1.1{\mu}g/kg/day$ for adults (women). The results clearly revealed that phthalate exposure is greater in children than in adults (women) due to the indoor dust.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.344-352
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• 2022

Accurate indoor localization of construction workers and mobile assets is essential in safety management. Existing positioning methods based on GPS, wireless, vision, or sensor based RTLS are erroneous or expensive in large-scale indoor environments. Tightly coupled sensor fusion mitigates these limitations. This research paper proposes a state-of-the-art positioning methodology, addressing the existing limitations, by integrating Stereo Visual Inertial Odometry (SVIO) with fiducial landmarks called AprilTags. SVIO determines the relative position of the moving assets or workers from the initial starting point. This relative position is transformed to an absolute position when AprilTag placed at various entry points is decoded. The proposed solution is tested on the NVIDIA ISAAC SIM virtual environment, where the trajectory of the indoor moving forklift is estimated. The results show accurate localization of the moving asset within any indoor or underground environment. The system can be utilized in various use cases to increase productivity and improve safety at construction sites, contributing towards 1) indoor monitoring of man machinery coactivity for collision avoidance and 2) precise real-time knowledge of who is doing what and where.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1337-1362
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• 2020

Advances in localization-based technologies and the increase in ubiquitous computing have led to a growing interest in location-based applications and services. High accuracy of the position of a wireless device is still a crucial requirement to be satisfied. Firstly, the rapid development of wireless communication technologies has affected the location accuracy of radio monitoring systems employed locally and globally. Secondly, the location is determined using standard complex computing methods and needs a relatively long execution time. In this paper, two geolocalization techniques, based on trigonometric and CORDIC computing processes, are proposed and implemented for Bluetooth-based indoor monitoring applications. Theoretical analysis and simulation results are investigated in terms of accuracy, scalability, and responsiveness. They show that the proposed techniques can locate a target wireless device accurately and are well suited for timing estimation.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2009.04a
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• pp.193-198
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• 2009

This study focuses on building an effective environmental control system for the ubiquitous housing environment. In order to build an effective environmental control system that will provide a comfortable, pleasant, and convenient environment for residents, information on how people cognize the indoor and outdoor environmental conditions, information on human beings, and information of the space should be studied. Also more studies need to be done in which method would be the best way to integrate these informations that would affect the users in the most positive way. The current environmental control system only carries the information on providing separate information of environmental factors such as light, temperature, humidity, heat, and sound. However, it is difficult to understand the energy efficiency of an architectural element through this system. Therefore, this study proposes an energy monitoring system utilizing spatial information.

• Journal of the Semiconductor & Display Technology
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• v.12 no.3
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• pp.35-39
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• 2013

In this paper, we developed an optical sheet for LED lighting with integrated $CO_2$ gas and temperature sensor which can monitor at the indoor environment. The optical sheet for LED lighting is fabricated through PMMA(Polymethyl methacrylate) injection process using mold. This research enables to fabricate the reflective sheet, light-guide plate and the prism sheet in a optical sheet. The fabricated sheet demonstrates higher intensity of optical efficiency compared with single-sided sheets. The $CO_2$ sensor was fabricated using NDIR(NON-Dispersive Infrared) method and it has $0.0235mV/V{\cdot}PPM$ sensitivity. The temperature sensor was fabricated using RTD(Resistance temperature detector) method and it has $0.563{\Omega}/^{\circ}C $sensitivity.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.2
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• pp.1-9
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• 2012

Wireless sensor nodes are widely used for various applications such as environmental monitoring. In this paper, the RSSI and PER are measured for the indoor environment with the various interferences such as obstacles(concrete walls, steel doors) and the 2.4GHz wireless LAN interference. Also, the RSSI and PER are measured for the outdoor environments. From the measured values of the RSSI and PER, the guideline for the stable operation of the wireless sensor network is suggested.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.6
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• pp.566-573
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• 2004

This paper describes the ubiquitous home network (uHome-net) testbed and LonRF intelligent devices based on LonWorks technology. These devices consist of Neuron Chip, RF transceiver, sensor, and other peripheral components. Using LonRF devices, a home control network can be simplified and most devices can be operated on LonWorks control network. Also, Indoor Positioning System (IPS) that can serve various location based services was implemented in uHome-net. Smart Badge of IPS, that is a special LonRF device, can measure the 3D location of objects in the indoor environment. In the uHome-net testbed, remote control service, cooking help service, wireless remote metering service, baby monitoring service and security ＆ fire prevention service were realized. This research shows the vision of the ubiquitous home network that will be emerged in the near future.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.350-352
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• 2018

In this paper, we propose a smart indoor garden aquaculture system using PIC. In the proposed smart indoor garden aquaculture system, the aquaphonics system circulates the nutrient solution of the aquarium, the filtrate tank, and the flowerpot. The automated control system that controls the state of the nutrient solution through the various sensors and controls the pump and valve is designed. As a result of the verification of the smart indoor garden aquaculture system proposed in this paper, it was confirmed that the environment suitable for the survival of fish and plants was maintained by monitoring water temperature, DO, pH measured in real time. The water level in aquarium and flower pot was controlled through automatic operation of the Electric vale and pump.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.1
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• pp.56-63
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• 2013

This study was aimed at developing and evaluating a diffusive sampling method using a barium hydroxide solution as an absorbent for measuring carbon dioxide ($CO_2$) in ambient air. The collected $CO_2$ concentration was calculated by the change of conductivity resulted in the reaction of $CO_3{^{2-}}$ and $Ba^{2+}$ in aqueous solution. The sampling rate for the diffusive sampler was determined 0.218 mL/min, as obtained from the slope of the linear correlation between the $CO_2$ mass collected by the diffusive sampler and the time-weighted $CO_2$ concentration with the active sampling method. The unexposed blank sampler sealed in aluminium foil-polyethylene laminated packets has remained stable during at least one-month storage period. A good correlation was observed between the diffusive sampler and active sampler with a coefficient of determination of 0.956. This diffusive sampler would be suitable for the indoor $CO_2$ concentration monitoring.