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Study on the MQTT protocol design for the application of the real-time HVAC System
Jung, Hun The Institute of Internet 2016 International Journal of Internet, Broadcasting an Vol.8 No.1
In this paper, the existing domestic HVAC systems, devices TCP / IP does not support the most, thereby, not performed remote management, it is necessary to regularly field service, inefficiency and cost bring a burden. This is through a comparison of the IoT-based primary, real-time protocol of what has become a hot topic recently, to be able to control and real-time monitoring through the CCU device in the HVAC system. Compare for this Internet of Things device for real-time monitoring and control of the XMPP, CoAP, MQTT main real-time protocol is used on. Finally, flexibility, light weight, based on MQTT a two-way messaging protocols with reliable message delivery, implements the protocol on the real-time HVAC system in the cloud platform.
Flow characteristics of crushed food wastes in household sewer pipes
( Junghun Lee ),( Young Sik Park ),( Wookeun Bae ) 한국폐기물자원순환학회 2011 ISWA Vol.2011 No.0
Food wastes, generated over 14,000 ton/day in Korea, are collected and hauled separately from the other municipal solid wastes. Most of the food wastes collected are processed in the composting or feed-manufacturing facilities, of which products are hardly marketable due to its marginal value. Anaerobic digestion in the sewage treatment plants (STPs) has been suggested as an alternative to manage the food wastes. This alternative is attractive as it can generate energy and save a greater part of the collection and hauling costs, only if the food wastes are transported to the STPs via existing sewer systems. A preliminary survey revealed that the crushed food wastes, discharged through household garbage disposers, may clog the lateral sewer pipes in apartment buildings. This study was performed to investigate the food-waste components that potentially clog the sewer pipes and the factors that affect a smooth transport of the food-waste particles. Six components of food-wastes, salted cabbages (mimic of Kimchi), brown seaweeds, rinds of a watermelons, rice grains, egg shells, and chicken bones, were prepared, and discharged individually or as a mixture into a transparent PVC pipe (Ø100 mm, L 9 m), after crushing by a commercial household garbage disposer. The PVC pipe had a slope of 1/100, 1/200, 1/400, or 0 and was equipped with an intentional hurdle whose hight was 0 (no hurdle), 1, 3, or 5 cm. The flow velocity of water in the pipe was controlled at approximately 0.1, 0.3, or 0.6 m/s. The results clearly revealed that food wastes with a relatively low density such as salted cabbages, brown seaweeds and rinds of watermelons flew well through the pipe even at 0.1 m/s of water flow velocity with any slope. The crushed salted cabbages flew well even with a 5-cm hurdle. The crushed brown seaweeds needed a higher water flow velocity (0.6 m/s) to clear a 5-cm hurdle. On the other hand, food wastes with higher density such as rice, egg shells and chicken bones were hardly transportable in the pipe even at 0.6 m/s of water flow velocity and with a 1/100 slope. A mixture of the food-waste components showed similar results: Smooth flow of lighter ones and deposition of heavier ones. In summary, the crushed food wastes with lower density are well transported through a household sewer pipe, while those with higher density are not and, thus, should not be introduced to a garbage disposer.
Efficient Environmental Monitoring Using Cost-Aware Path Planning
Junghun Suh,Songhwai Oh 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10
This paper presents an efficient environmental monitoring strategy that considers the information gain along the trajectory of a robot. In order to monitor environmental parameters such as temperature and chemical concentration, an estimation method based on Gaussian process regression is used. The goal of this paper is to model accurate spatio-temporal phenomena by reducing the uncertainty over the surveillance region. A cost-aware path planning based environmental monitoring is desirable for mobile sensor networks since robots are coordinated to follow a trajectory with the maximum accumulated information gain, as well as the traveling distance. The proposed method with respect to different sampling methods is demonstrated in simulations.