Cost-Based Predictive Spatiotemporal Join

A predictive spatiotemporal join finds all pairs of moving objects satisfying a join condition on future time and space. In this paper, we present CoPST, the first and foremost algorithm for such a join using two spatiotemporal indexes. In a predictive spatiotemporal join, the bounding boxes of the outer index are used to perform window searches on the inner index, and these bounding boxes enclose objects with increasing laxity over time. CoPST constructs globally tightened bounding boxes "on the fly" to perform window searches during join processing, thus significantly minimizing overlap and improving the join performance. CoPST adapts gracefully to large-scale databases, by dynamically switching between main-memory buffering and disk-based buffering, through a novel probabilistic cost model. Our extensive experiments validate the cost model and show its accuracy for realistic data sets. We also showcase the superiority of CoPST over algorithms adapted from state-of-the-art spatial join algorithms, by a speedup of up to an order of magnitude.     

R&D activities of the liquid breeder blanket in Korea

A liquid breeder blanket has been developed in parallel with the International Thermonuclear Experimental Reactor (ITER) Test Blanket Module (TBM) program in Korea. The Korea Atomic Energy Research Institute (KAERI) has developed the common fields of a solid TBM such as design tools, structural material, fabrication methods, and He cooling technology to support this concept for the ITER. Also, other fields such as a liquid breeder technology and tritium extraction have been developed from the designed liquid TBM. For design tools, system codes for safety analysis such as Multi-dimensional Analysis of Reactor Safety (MARS) and GAs Multi-component Mixture Analysis (GAMMA) were developed for He coolant and liquid breeder. For the fabrication methods, Ferritic Martensitic Steel (FMS) to FMS and Be to FMS joinings with a Hot Isostatic Pressing (HIP) were developed and verified with a high heat flux test of up to 0.5–1.0 MW/m². Moreover, three mockups were successfully fabricated and a 10-channel prototype is being fabricated to make a rectangular channel FW. For the integrity of the joining, two high heat flux test facilities were constructed, and one using an electron beam has been constructed. With the 6 MPa nitrogen loop, a basic heat transfer experiment for code validation was performed. From the verification of the components such as preheater and circulator, a 9 MPa He loop was constructed, and it supplies high temperature (500 °C) and pressure (8 MPa) He to the high heat flux test facility. For an electromagnetic (EM) pump development for circulating the liquid breeder, magnetohydrodynamic (MHD) experiment, and flow corrosion test, a PbLi breeder loop was constructed. From the performance test, the EM pump and magnet show their capability, and flow and static corrosion tests including oxide coating for corrosion protection were performed. For tritium extraction from the liquid breeder, a gas–liquid contact method was adopted and a tritium extraction chamber was constructed. For measurement of the tritium amount in the liquid breeder, permeation sensors have been developed.     

Integrated approach of streaming 3d multimedia contents in real-time for mobile devices

It is popular to watch a 3D video through a 3D display nowadays. However, it is still difficult to enjoy the 3D multimedia contents with a mobile device even if a mobile device with a 3D display is currently introduced into the market. The main technological challenges for watching 3D contents via the mobile devices can be identified as the following: generating and streaming 3D contents. Generating 3D contents requires extra computational resources. Moreover, streaming 3D contents demands additional network bandwidth for receiving and transmitting the 3D data. To overcome these technological challenges, we propose ReMA, a novel 3D video streaming system in this paper. We devised a novel architecture for transmitter, receiver, and a distribution system to efficiently disseminate and generate 3D videos for the mobile devices. We implemented ReMA in a real test-bed and conducted a thorough empirical evaluation study to see the feasibility of streaming 3D contents for the mobile devices. Based on our empirical study, the resulting system presents a great promise in streaming 3D video in real-time to the mobile devices.     

Fuzzy GMDH-type neural network model and its application to forecasting of mobile communication

In this paper, the fuzzy group method data handling-type (GMDH) neural networks and their application to the forecasting of mobile communication systems are described. At present, the GMDH family of modeling algorithms discovers the structure of empirical models and it gives only the way to get the most accurate identification and demand forecasts in case of noised and short input sampling. In distinction to neural networks, the results are explicit mathematical models, obtained in a relative short time. In this paper, an adaptive learning network is proposed as a kind of neural-fuzzy GMDH. The proposed method can be reinterpreted as a multi-stage fuzzy decision rule which is called the neural-fuzzy GMDH. The GMDH-type neural networks have several advantages compared with conventional multi-layered GMDH models. Therefore, many types of nonlinear systems can be automatically modeled by using the neuro-fuzzy GMDH. A computer program is developed and successful applications are shown in the field of estimating problems of mobile communication with a number of factors considered.     

Effectively reinforcing roles of the networked silica prepared using 3,3′-bis(triethoxysilylpropyl)tetrasulfide in the physical properties of SBR compounds

The networked silica having pre-fabricated networks among silica particles is a new concept for the reinforcement of rubber compounds. The networked silica was designed to improve the fuel efficiency of tires while eliminating the disadvantages such as precure and ethanol production that arise in the conventional reinforcing system using coupling reagents. The networked silica was prepared using bis(triethoxysilylpropyl)tetrasulfide (TESPT) as a connecting chemical at various loading levels. The styrene–butadiene rubber (SBR) compounds reinforced with the networked silica exhibited low filler–filler interaction and high rubber–filler interaction due to the entanglements between the rubber molecules and the connecting chains of the networked silica. The increased physical interaction improved the elastic properties and wear resistance, while lowering the rolling resistance of the rubber compounds, resulting in long tire service life and high automobile fuel efficiency. The enhanced physical properties of the SBR compounds reinforced with the networked silica supported their promising potential as reinforcing fillers for tire manufacture. The networked silica can readily replace the conventional silica-reinforced system, without requiring major modification of the processing conditions.     

Energy Transfer in Ionic‐Liquid‐Functionalized Inorganic Nanorods for Highly Efficient Photocatalytic Applications

Energy transfer in self‐assembled ionic liquids (ILs) and iron oxyhydroxide nanocrystals and the controlled surface chemistry of functionalized nanomaterials for photocatalytic applications are reported. Self‐assembled ILs play the role of multifunctional materials in terms of constructing a well‐designed nanostructure, controlling the surface chemistry, and triggering the energy transfer of functionalized materials. IL‐functionalized β‐FeOOH nanorods show ≈10‐fold higher performances than those of commercial materials due to the synergistic effect of well‐defined nanomaterials in diffusion‐controlled reactions, specific interactions with target pollutants, and energy transfers in hybrid materials. In particular, the energy transfer in C₄MimCl‐functionalized β‐FeOOH nanorods enhances photocatalytic activity due to the generation of Fe²⁺. The strategy described herein provides new insight into the rational design of functionalized inorganic nanomaterials for applications in emerging technologies.     

Free-running ADC- and FPGA-based signal processing method for brain PET using GAPD arrays

Currently, for most photomultiplier tube (PMT)-based PET systems, constant fraction discriminators (CFD) and time to digital converters (TDC) have been employed to detect gamma ray signal arrival time, whereas anger logic circuits and peak detection analog-to-digital converters (ADCs) have been implemented to acquire position and energy information of detected events. As compared to PMT the Geiger-mode avalanche photodiodes (GAPDs) have a variety of advantages, such as compactness, low bias voltage requirement and MRI compatibility. Furthermore, the individual read-out method using a GAPD array coupled 1:1 with an array scintillator can provide better image uniformity than can be achieved using PMT and anger logic circuits. Recently, a brain PET using 72 GAPD arrays (4×4 array, pixel size: 3 mm×3 mm) coupled 1:1 with LYSO scintillators (4×4 array, pixel size: 3 mm×3 mm×20 mm) has been developed for simultaneous PET/MRI imaging in our laboratory. Eighteen 64:1 position decoder circuits (PDCs) were used to reduce GAPD channel number and three off-the-shelf free-running ADC and field programmable gate array (FPGA) combined data acquisition (DAQ) cards were used for data acquisition and processing. In this study, a free-running ADC- and FPGA-based signal processing method was developed for the detection of gamma ray signal arrival time, energy and position information all together for each GAPD channel. For the method developed herein, three DAQ cards continuously acquired 18 channels of pre-amplified analog gamma ray signals and 108-bit digital addresses from 18 PDCs. In the FPGA, the digitized gamma ray pulses and digital addresses were processed to generate data packages containing pulse arrival time, baseline value, energy value and GAPD channel ID. Finally, these data packages were saved to a 128 Mbyte on-board synchronous dynamic random access memory (SDRAM) and then transferred to a host computer for coincidence sorting and image reconstruction. In order to evaluate the functionality of the developed signal processing method, energy and timing resolutions for brain PET were measured via the placement of a 6 μCi ²²Na point source at the center of the PET scanner. Furthermore the PET image of the hot rod phantom (rod diameter: from 2.5 mm to 6.5 mm) with activity of 1 mCi was simulated, and then image acquisition experiment was performed using the brain PET. Measured average energy resolution for 1152 GAPD channels and system timing resolution were 19.5% (FWHM%) and 2.7 ns (FWHM), respectively. With regard to the acquisition of the hot rod phantom image, rods could be resolved down to a diameter of 2.5 mm, which was similar to simulated results. The experimental results demonstrated that the signal processing method developed herein was successfully implemented for brain PET. This reduced the complexity, cost and developing duration for PET system relative to normal PET electronics, and it will obviously be useful for the development of high-performance investigational PET systems.