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Location-Based TDMA MAC for Reliable Aeronautical Communications
Hyungjun Jang,Eunkyung Kim,Jae-Joon Lee,Jaesung Lim IEEE 2012 IEEE transactions on aerospace and electronic syst Vol.48 No.2
<P>The growth of data traffic as air traffic increases is leading to bottlenecks. We propose a new time division multiple access (TDMA) protocol termed location-based TDMA (LBTM) to accommodate increasing data traffic and air-to-air communications. LBTM provides all three modes of communication: unicast, multicast, and broadcast. ACK needs a long guard time for reliable multicast in the aeronautical environment, because it is a long distance communication system. LBTM uses location information to overcome this problem. We can reduce the guard time of ACK and prevent collisions. In our scheme, multicast aircraft calculate ACK arrival time to ensure that ACKs arrive at the sender at different times. Therefore, LBTM reduces the amount of guard time of ACK and the total average time to complete a reliable multicast MAC request. This results in a significant increase in network utilization and throughput.</P>
Note on Tangible AR Interaction based on Fingertip Touch using Small-sized Markers
Hyungjun Park,Ho-Kyun Jung,Sang-Jin Park (사)한국CDE학회 2013 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8
Although big-sized markers are good for accurate marker recognition and tracking, they are easily occluded by other objects and deteriorate natural visualization and level of immersion during user interaction in AR environments. In this paper, we propose an approach to exploiting the use of rectangular markers to support tangible AR interaction based on fingertip touch using small-sized markers. It basically adjusts the length, width, and interior area of rectangular markers to make them more suitably fit to longish objects like fingers. It also utilizes convex polygons to resolve the partial occlusion of a marker and properly enlarges the pattern area of a marker while adjusting its size without deteriorating the quality of marker detection. We obtained encouraging results from users that the approach is accurate and tangible enough to support a pseudo feeling of touching virtual products with human hands or fingertips during design evaluation of digital handheld products.
Pantograph and Stagger Inspection Using Image Processing Technique
HyungJun Kim,Keehong Um 한국멀티미디어학회 2009 한국멀티미디어학회 국제학술대회 Vol.2009 No.-
We present an image processing technique for monitoring the interaction between the pantograph and the catenary system of the Korean TIX (tilting train express) train. Due to the displacement of the contact point with respect to the reference position, an image processing analysis of each frame is performed in order to detect stagger of trolley wire automatically. The proposed approach is very efficient and produces desirable output data.
HyungJun Kim,Injun Lee,Sunghoon Hong 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1
A disposal of radioactive wastes is one of the critical issues in our society. Considering upcoming plans for dismantling of nuclear power plants, this problem is inevitable and should be discussed very carefully. There are variety of methods to handle with radioactive wastes, including Incineration, conventional gasification and plasma gasification. Among them, plasma gasification process is in the limelight due to its eco-friendly & stable operation, and large volume reduction effects. However, a fatal disadvantage is that it consumes more electric power than other methods, this leaves us a question of whether this process is indeed economical. Within the scope of this paper, I would like to introduce 4 cases which plasma facilities were evaluated economically in worldwide, and reach the conclusion on the economic feasibility of plasma process.
A Study on Plasma Torch Melter’s Optimum Start-up Operation Condition
HyungJun Kim,Sunghoon Hong 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1
A plasma torch is a kind of equipment that utilizes an electric arc to dissociate a gas and transfer an electric energy to the gas to generate very high temperature flame. KHNP-CRI has been developed the Plasma Torch Melter (PTM) to reduce radioactive waste disposal volumes and drop the radiation level of wastes. As you guess, there is required condition for proper start-up operation like current, voltage, plasma gas flow, cooling water flow, temperature in melter and so on. Thus, the optimum start-up operation condition of plasma torch will be estimated experimentally in this paper.
Predictive Data Delivery to Mobile Users Through Mobility Learning in Wireless Sensor Networks
HyungJune Lee,Wicke, Martin,Kusy, Branislav,Gnawali, Omprakash,Guibas, Leonidas IEEE 2015 IEEE Transactions on Vehicular Technology VT Vol.64 No.12
<P>We consider applications, such as indoor navigation, evacuation, or targeted advertising, where mobile users equipped with a smartphone-class device require access to sensor network data measured in their proximity. Specifically, we focus on efficient communication protocols between static sensors and users with changing location. Our main contribution is to predict a set of possible future paths for each user and store data at sensor nodes with which the user is likely to associate. We use historical data of radio connectivity between users and static sensor nodes to predict the future user-node associations and propose a network optimization process, i.e., data stashing, which uses the predictions to minimize network and energy overheads of packet transmissions. We show that data stashing significantly decreases routing cost for delivering data from stationary sensor nodes to multiple mobile users compared with routing protocols where sensor nodes immediately deliver data to the last known association nodes of mobile users. We also show that the scheme provides better load balancing, avoiding collisions and consuming energy resources evenly throughout the network, leading to longer overall network lifetime. Finally, we demonstrate that even limited knowledge of the location of future users can lead to significant improvements in routing performance.</P>