• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.1
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• pp.129-136
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• 2004

In this paper, we proposed quad variable rates ADPCM coding method for efficient speech transmission and real time porcessing is implemented on TMS320C6711-DSP. The modified ADPCM with four variable coding rates, 16[kbps], 24[kbps], 32[kbps] and 40[kbps] are used for speech window samples for good quality speech transmission at a small data bits and real time encoding and decoding is implemented using DSP. ZCR is used to identify the influence of the noise on the speech signal and to decide the rate change threshold. For noise superior signals, low coding rates are applied to minimize data bit and for noise inferior signals, high coding rates are applied to enhance the speech quality. In most speech telecommunications, silent period takes more than half of the signals, speech quality close to 40[kbps] can be obtained at comparabley low data bits and this is shown by simulation and experiments. TMS320C6711-DSK board has 128K flash memory and performance of 1333MIPS and has meets the requirements for real time implementation of proposed coding algorithm.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.4
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• pp.863-872
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• 2015

Kernel rootkit is recognized as one of the most severe and widespread threats to corrupt the integrity of an operating system. Without an external monitor as a root of trust, it is not easy to detect kernel rootkits which can intercept and modify communications at the interfaces between operating system components. To provide such a monitor isolated from an operating system that can be compromised, most existing solutions are based on external hardware. Unlike those solutions, we develop a kernel introspection system based on the ARM TrustZone technology without incurring extra hardware cost, which can provide a secure memory space in isolation from the rest of the system. We particularly use a secure timer to implement an autonomous switch between secure and non-secure modes. To ensure integrity of reference, this system measured reference from vmlinux which is a kernel original image. In addition, the flexibility of monitoring block size can be configured for efficient kernel introspection system. The experimental results show that a secure kernel introspection system is provided without incurring any significant performance penalty (maximum 6% decrease in execution time compared with the normal operating system).

• The KIPS Transactions:PartC
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• v.14C no.4
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• pp.371-382
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• 2007

In this paper, we propose a real-time sensor node platform that efficiently manages periodic and aperiodic tasks. Since existing sensor node platforms available in literature focus on minimizing the usage of memory and power consumptions, they are not capable of supporting the management of tasks that need their real-time execution and fast average response time. We first analyze how to structure periodic or aperiodic task decomposition in the TinyOS-based sensor node platform as regard to guaranteeing the deadlines of ail the periodic tasks and aiming to providing aperiodic tasks with average good response time. Then we present the application and efficiency of the proposed real-time sensor node platform in the sensor node equipped with a low-power 8-bit microcontroller, an IEEE802.15.4 compliant 2.4GHz RF transceiver, and several sensors. Extensive experiments show that our sensor node platform yields efficient performance in terms of three significant, objective goals: deadline miss ratio of periodic tasks, average response time of aperiodic tasks, and processor utilization of periodic and aperiodic tasks.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.726-734
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• 2015

Relational databases used by structuralizing data are the most widely used in data management at present. However, in relational databases, service becomes slower as the amount of data increases because of constraints in the reading and writing operations to save or query data. Furthermore, when a new task is added, the database grows and, consequently, requires additional infrastructure, such as parallel configuration of hardware, CPU, memory, and network, to support smooth operation. In this paper, in order to improve the web information services that are slowing down due to increase of data in the relational databases, we implemented a model to extract a large amount of data quickly and safely for users by processing Hadoop Distributed File System (HDFS) files after sending data to HDFSs and unifying and reconstructing the data. We implemented our model in a Web-based civil affairs system that stores image files, which is irregular data processing. Our proposed system's data processing was found to be 0.4 sec faster than that of a relational database system. Thus, we found that it is possible to support Web information services with a Hadoop-based big data processing technique in order to process a large amount of data, as in conventional relational databases. Furthermore, since Hadoop is open source, our model has the advantage of reducing software costs. The proposed system is expected to be used as a model for Web services that provide fast information processing for organizations that require efficient processing of big data because of the increase in the size of conventional relational databases.

• Archives of design research
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• v.18 no.1 s.59
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• pp.49-58
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• 2005

Focusing on the information sender, message, channel, and receiver, the existing information theory deals with the noise, information contents, and probability of choice, which involve in the process of information transmission. In the current digital environment, besides simply conveying information itself through media, the important issue is how to efficiently convey information. Therefore, we need to analyze the theory in different perspective, and to research the Information redundancy for the methodology of information design. The redundancy causes the receiver to have attraction to the information and to reduce its contents due to its supplement and repetition. So it can play a role of efficient communication method. The concept of redundancy is applied to the communication of art such as literature, architecture, painting, and design to accomplish efficient communication. In order to get persuasive information design for the receiver's perspective we need to make use of this concept. The redundancy can be applied with the technical aspect of multimedia and Interaction, which add supplemental expression, or sort of event for the receiver's experience and memory. In the process of constructing information it can be applied with the structure of gaming redundancy, entropy, the accumulating communication code using entertaining feature, and storytelling methodology. The noise and entropy could be used for the means of making redundancy, not the obstacle to information. The redundancy gives the receiver attraction on the information and makes them have strong will of interpreting it so that the purpose of conveying information will be accomplished efficiently.

• Journal of KIISE:Information Networking
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• v.37 no.3
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• pp.175-186
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• 2010

Due to the emergence of new application programs and the fast growth of Internet users, Internet routers are required to provide the quality of services according to the class of input packets, which is identified by wire-speed packet classification. For a pre-defined rule set, by performing multi-dimensional search using various header fields of an input packet, packet classification determines the highest priority rule matching to the input packet. Efficient packet classification algorithms have been widely studied. Tuple pruning algorithm provides fast classification performance using hash-based search against the candidate tuples that may include matching rules. Bloom filter is an efficient data structure composed of a bit vector which represents the membership information of each element included in a given set. It is used as a pre-filter determining whether a specific input is a member of a set or not. This paper proposes new tuple pruning algorithms using Bloom filters, which effectively remove unnecessary tuples which do not include matching rules. Using the database known to be similar to actual rule sets used in Internet routers, simulation results show that the proposed tuple pruning algorithm provides faster packet classification as well as consumes smaller memory amount compared with the previous tuple pruning algorithm.

• The KIPS Transactions:PartA
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• v.16A no.3
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• pp.159-168
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• 2009

In this paper, we present an efficient way of implementing OpenGL ES 1.1 standard for the environments with hardware-supported OpenGL API, such as desktop PCs. Although OpenGL ES was started from the existing OpenGL features, it becomes a new three-dimensional graphics library customized for embedded systems through introducing fixed-point arithmetic operations, buffer management with fixed-point data type supports, completely new texture mapping functionalities and others. Currently, it is the official three dimensional graphics library for Google Android, Apple iPhone, PlayStation3, etc. In this paper, we achieved improvements on the arithmetic operations for the fixed-point number representation, which is the most characteristic data type for OpenGL ES. For the conversion of fixed-point data types to the floating-point number representations for the underlying OpenGL, we show the way of efficient conversion processes even with satisfying OpenGL ES standard requirements. We also introduced a simple memory management scheme to mange the converted data for the buffer containing fixed-point numbers. In the case of texture processing, the requirements in both standards are quite different and thus we used completely new software-implementations. Our final implementation result of OpenGL ES library provides all of over than 200 functions in OpenGL ES 1.1 standard and completely passed its conformance test, to show its compliance with the standard. From the efficiency viewpoint, we measured its execution times for several OpenGL ES-specific application programs and achieved at most 33.147 times improvements, to become the fastest one among the OpenGL ES implementations in the same category.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.3
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• pp.26-31
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• 2009

A new LFSR based test compression scheme is proposed by reducing the maximum number of specified bits in the test cube set, smax, virtually. The performance of a conventional LFSR reseeding scheme highly depends on smax. In this paper, by using different clock frequencies between an LFSR and scan chains, and grouping the scan cells, we could reduce smax virtually. H the clock frequency which is slower than the clock frequency for the scan chain by n times is used for LFSR, successive n scan cells are filled with the same data; such that the number of specified bits can be reduced with an efficient grouping of scan cells. Since the efficiency of the proposed scheme depends on the grouping mechanism, a new graph-based scan cell grouping heuristic has been proposed. The simulation results on the largest ISCAS 89 benchmark circuit show that the proposed scheme requires less memory storage with significantly smaller area overhead compared to the previous test compression schemes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.7
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• pp.48-56
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• 2011

Recently, new storage device SSD(Solid State Disk) based on NAND flash memory is gradually replacing HDD(Hard Disk Drive) in mobile device and thus a variety of research efforts are going on to find the cost-effective ways of performance improvement. By increasing the NAND flash channels in order to enhance the bandwidth through parallel processing, DRAM buffer which acts as a buffer cache between host(PC) and NAND flash has become the bottleneck point. To resolve this problem, this paper proposes an efficient low-cost scheme to increase SSD performance by improving DRAM buffer bandwidth through scheduling techniques which utilize DRAM multi-banks. When both host and NAND flash multi-channels request access to DRAM buffer concurrently, the proposed technique checks their destination and then schedules appropriately considering properties of DRAMs. It can reduce overheads of bank active time and row latency significantly and thus optimizes DRAM buffer bandwidth utilization. The result reveals that the proposed technique improves the SSD performance by 47.4% in read and 47.7% in write operation respectively compared to conventional methods with negligible changes and increases in the hardware.

• The Journal of Society for e-Business Studies
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• v.18 no.2
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• pp.153-173
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• 2013

The ontology has been gaining increasing interests by recent arise of the semantic web and related technologies. The focus is mostly on inference query processing that requires high-level techniques for storage and searching ontologies efficiently, and it has been actively studied in the area of semantic-based searching. W3C's recommendation is to use RDFS and OWL for representing ontologies. However memory-based editors, inference engines, and triple storages all store ontology as a simple set of triplets. Naturally the performance is limited, especially when a large-scale ontology needs to be processed. A variety of researches on proposing algorithms for efficient inference query processing has been conducted, and many of them are based on using proven relational database technology. However, none of them had been successful in obtaining the complete set of inference results which reflects the five characteristics of the ontology properties. In this paper, we propose a new index structure called hyper cube index to efficiently process inference queries. Our approach is based on an intuition that an index can speed up the query processing when extensive inferencing is required.