• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.1-10
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• 2009

As a demand for the portable device requiring smaller size and better performance is in hike, reducing the size of conventionally used planar 2 dimensional chip cannot be a solution for the enhancement of the semiconductor chip technology due to an increase in RC delay among interconnects. To address this problem, a new technology - "3 dimensional (3D) IC chip stack" - has been emerging. For the integration of the technology, several new key unit processes (e.g., silicon through via, wafer thinning and wafer alignment and bonding) should be developed and much effort is being made to achieve the goal. As a result of such efforts, 4 and 8 chip-stacked DRAM and NAND structures and a system stacking CPU and memory chips vertically were successfully developed. In this article, basic theory, configurations and key unit processes for the 3D IC chip integration, and a current tendency of the technology are explained. Future opportunities and directions are also discussed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12B
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• pp.831-837
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• 2005

Personal general purpose computer(PC) has been evolved from desktop to portable mobile device such as tablet PC and PDA. Technology innovation on semiconductor have made it possible to package a reasonably Powerful Processor and memory subsystem with advanced input/output devices. At last these subsystems are miniaturized into wearable system. Wearable computer has recently gained attention as the post PC in the ubiquitous environment. Wearable computing becomes more and more feasible and receives growing attention throughout industry and the consumer marketplaces. This paper proposed and developed WPS that has multimedia features and network features as a wearable embedded platform. We explain the form, overall architecture, functions and user applications of this WPS. This paper also discusses the form of next generation computer platform with intuitive user interfaces and well designed applications in the future.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.1
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• pp.35-45
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• 2007

The log data collected from mobile devices contains diverse meaningful and practical personal information. However, this information is usually ignored because of its limitation of memory capacity, computation power and analysis. We propose a novel method that detects landmarks of meaningful information for users by analyzing the log data in distributed modules to overcome the problems of mobile environment. The proposed method adopts Bayesian probabilistic approach to enhance the inference accuracy under the uncertain environments. The new cooperative modularization technique divides Bayesian network into modules to compute efficiently with limited resources. Experiments with artificial data and real data indicate that the result with artificial data is amount to about 84% precision rate and about 76% recall rate, and that including partial matching with real data is about 89% hitting rate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.10
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• pp.1862-1878
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• 2011

With the advances in wireless communication technology and the advent of smartphones, research on location-based services (LBSs) is being actively carried out. In particular, several spatial index methods have been proposed to provide efficient LBSs. However, finding an optimal indexing method that balances query performance and index size remains a challenge in the case of wireless environments that have limited channel bandwidths and device resources (computational power, memory, and battery power). Thus, mechanisms that make existing spatial indexing techniques more efficient and highly applicable in resource-limited environments should be studied. Bitmap-based Spatial Indexing (BSI) has been designed to support LBSs, especially in wireless broadcast environments. However, the access latency in BSI is extremely large because of the large size of the bitmap, and this may lead to increases in the search time. In this paper, we introduce a Selective Bitmap-based Spatial Indexing (SBSI) technique. Then, we propose an Adaptive Bitmap-based Spatial Indexing (ABSI) to improve the tuning time in the proposed SBSI scheme. The ABSI is applied to the distribution of geographical objects in a grid by using the Hilbert curve (HC). With the information in the ABSI, grid cells that have no objects placed, (i.e., 0-bit information in the spatial bitmap index) are not tuned during a search. This leads to an improvement in the tuning time on the client side. We have carried out a performance evaluation and demonstrated that our SBSI and ABSI techniques outperform the existing bitmap-based DSI (B DSI) technique.

• Journal of Internet Computing and Services
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• v.9 no.6
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• pp.117-125
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• 2008

With increase of concern about the Ubiquitous application, the necessity of the computer system which is miniaturized is becoming larger. The ARM processor is showing a high share from embedded system market. In this paper, ideal method for RTD-1000 controller construction and development is described using ARM microcontroller. Existing RTD-1000 measures distance of disconnection or defect of sensing casket by measuring receiving reflected wave which was sent via copper wire inside the leaking sensing rod. Using this RTD-1000, leakage and breakage of water and oil pipe can be sensed and it reports damage results to the networks. But, existing RTD-1000 wastes hardware resources much and costs a great deal to installation. Also, it needs a cooling device because the heating problem, and has some problem of the secondary memory unit such as the hard disk. So, long tenn maintenance has some problems in the outside install place. In this paper, for the resolving the problem of RTD-1000, RTD-1000A embedded system based on ARM is proposed and simulated.

• Journal of the Institute of Convergence Signal Processing
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• v.6 no.4
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• pp.169-175
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• 2005

In recent, implementation of the embedded system is gradually in the spotlight of world-wide by information technology(IT) engineers. By this time, an implementation of real time system is limited on image acquisition and processing system in practical. In this paper, the USB camera interface system based on the embedded linux OS is implemented using USB 2.0 camera with low cost. This system can obtain image signals into the memory via X-hyper255B processor from USB camera. It is need to initialize USB camera by the Video4Linux for the kernel device driver. From the system image capturing and image processing can be performed. It is confirmed that the image data can be transformed to packet of Network File System(NFS) and connected to the internetwork, then the data can be monitored from the client computer connected to the internetwork.

• Ceramist
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• v.21 no.2
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• pp.4-18
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• 2018

Lastly, neuromorphic computing chip has been extensively studied as the technology that directly mimics efficient calculation algorithm of human brain, enabling a next-generation intelligent hardware system with high speed and low power consumption. Three-terminal based synaptic transistor has relatively low integration density compared to the two-terminal type memristor, while its power consumption can be realized as being so low and its spike plasticity from synapse can be reliably implemented. Also, the strong electrical interaction between two or more synaptic spikes offers the advantage of more precise control of synaptic weights. In this review paper, the results of synaptic transistor mimicking synaptic behavior of the brain are classified according to the channel material, in order of silicon, organic semiconductor, oxide semiconductor, 1D CNT(carbon nanotube) and 2D van der Waals atomic layer present. At the same time, key technologies related to dielectrics and electrolytes introduced to express hysteresis and plasticity are discussed. In addition, we compared the essential electrical characteristics (EPSC, IPSC, PPF, STM, LTM, and STDP) required to implement synaptic transistors in common and the power consumption required for unit synapse operation. Generally, synaptic devices should be integrated with other peripheral circuits such as neurons. Demonstration of this neuromorphic system level needs the linearity of synapse resistance change, the symmetry between potentiation and depression, and multi-level resistance states. Finally, in order to be used as a practical neuromorphic applications, the long-term stability and reliability of the synapse device have to be essentially secured through the retention and the endurance cycling test related to the long-term memory characteristics.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.10
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• pp.438-442
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• 2005

Si nanocrystal (Si NC) memory device has several advantages such as better retention, lower operating voltage, reduced punch-through and consequently a smaller cell area, suppressed leakage current. However, the physical and electrical reasons for this behavior are not completely understood but could be related to interface states of Si NCs. In order to find out this effect, we characterized electrical properties of Si NCs embedded in a SiO$_{2}$ layer by scanning probe microscopy (SPM). The Si NCs were generated by the laser ablation method with compressed Si powder and followed by a sharpening oxidation. In this step Si NCs are capped with a thin oxide layer with the thickness of 1$\~$2 nm for isolation and the size control. The size of 51 NCs is in the range of 10$\~$50 m and the density around 10$^{11}$/cm$^{2}$ It also affects the interface states of Si NCs, resulting in the change of electrical properties. Using a conducting tip, the charge was injected directly into each Si NC, and the image contrast change and dC/dV curve shift due to the trapped charges were monitored. The results were compared with C-V characteristics of the conventional MOS capacitor structure.

• Journal of the Korean Ceramic Society
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• v.32 no.12
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• pp.1408-1416
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• 1995

Microstructure and ferroelectric properties of sol-gel derived PZT(52/48) and PT interlayered PZT(52/48) thin films on Pt/Ti/SiO2/Si substrates were investigated. Films were fabricated using Acetylacetone chelated PT and PZT(52/48) sols. PZT(52/48) thin films annealed at $700^{\circ}C$ for 20 min showed the rosette structure with the size of 1.2~1.6${\mu}{\textrm}{m}$ and the pyrochlore phse was contained. PT interlayered PZT thin films, which is inserted by PbTiO3 thin layer with the thickness of 130 $\AA$ between PZT thin film and electrode, consisted of a single perovskite phase after annealing above 55$0^{\circ}C$. They exhibited the uniform and columnar grains of 0.1~0.16${\mu}{\textrm}{m}$, which are applicable for microelectronic device including non-volatile memory. Typical P-E hysteresis loops could be obtained from PT interlayered PZT thin film at as low as the annealing temperature of 50$0^{\circ}C$. Ferroelectric properties of PT interlayered PZT thin films were improved as increasing annealing temperature up to $700^{\circ}C$, and then deteriorated at 75$0^{\circ}C$. PZT(52/48) and PT interlayered PZT(52/48) thin film annealed at $700^{\circ}C$ for 20 min displayed Ps=38.8$\mu$C/$\textrm{cm}^2$, Pr=10.0$\mu$C/$\textrm{cm}^2$, Ec=65.3 kV/cm and Ps=28.5$\mu$C/$\textrm{cm}^2$, Pr=9.8$\mu$C/$\textrm{cm}^2$, Ec=76.1 kV/cm, respectively.

• Journal of Digital Convergence
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• v.12 no.11
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• pp.265-272
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• 2014

This study suggests a system for preventing and coping with diverse industrial accidents available for taking place in the industrial field by designing a context-aware system of the solar cell equipment with the use of multi-sensor. It installs multi-sensor in the surrounding and major positions of the solar cell equipment, acquires data on the surrounding situations and solar cell equipment from this device, and then save it into the local memory and transmits it to the server. The saved data recognizes a situation based on the context-aware algorithm and judges depending on the perceived result. An administrator comes to have environment available for monitoring the status on the production field and equipments with real time according to the judged outcome through the context-aware algorithm. The context-aware system in the industrial field, which is put today in the ubiquitous environment, will become a service of offering appropriate information for dealing with industrial accidents through real-time inspection.