• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.821-828
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• 2004

To analyze the usage information of system and network resources to the each grid application by measuring the real time traffic and calculating the statistic information, we suggested the kernel-based monitoring methods by researching the efficient monitoring method. This method use small system resourcesand measure the monitoring information accurately with less delay than the usual packet capture methods such as tcpdump. Also we implemented the monitoring systems which can monitor the used resources of system and network for grid application using the suggested kernel-based monitoring method. This research can give the useful information to the development of grid application and to grid network scheduler which can assign the proper resources to the grid application to perform efficiently. Network administrator can decide whether the expansion of network is required or not using the monitoring information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7A
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• pp.683-694
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• 2002

In this paper, a digital image compression codec using 2D DWT(Discrete Wavelet Transform) is designed using the FPGA technology for real time operation The implemented image compression codec using wavelet decomposition consists of a wavelet kernel part for wavelet filtering process, a quantizer/huffman coder for quantization and huffman encoding of wavelet coefficients, a memory controller for interface with external memories, a input interface to process image pixels from A/D converter, a output interface for reconstructing huffman codes, which has irregular bit size, into 32-bit data having regular size data, a memory-kernel buffer to arrage data for real time process, a PCI interface part, and some modules for setting timing between each modules. Since the memory mapping method which converts read process of column-direction into read process of the row-direction is used, the read process in the vertical-direction wavelet decomposition is very efficiently processed. Global operation of wavelet codec is synchronized with the field signal of A/D converter. The global hardware process pipeline operation as the unit of field and each field and each field operation is classified as decomposition levels of wavelet transform. The implemented hardware used FPGA hardware resource of 11119(45%) LAB and 28352(9％) ESB in FPGA device of APEX20KC EP20k600CB652-7 and mapped into one FPGA without additional external logic. Also it can process 33 frames(66 fields) per second, so real-time image compression is possible.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5B
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• pp.295-303
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• 2005

Recently, according to the rapid increase of Web users, various kinds of Web applications have been being developed. Hence, Web QoS(Quality of Service) becomes a critical issue in the Web services, such as e-commerce, Web hosting, etc. Nevertheless, most Web servers currently process various requests from Web users on a FIFO basis, which can not provide differentiated QoS. This paper presents a load balancing method to provide differentiated Web QoS in clustering web server. The first is the kernel-level approach, which is adding a real-time scheduling process to the operating system kernel to maintain the priority of user requests determined by the scheduling process of Web server. The second is the load-balancing approach, which uses IP-level masquerading and tunneling technology to improve reliability and response speed upon user requests. The third is the dynamic load-balancing approach, which uses the parameters related to the MIB-II of SNMP and the parameters related to load of the system such as memory and CPU.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.311-318
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• 2001

In recent years, users\` demands for multimedia service are increasing because of a diffusion of internet. Server systems, however, offer inefficient multimedia data service to users. Multimedia applications often transfer the same data between shared devices at very high rates, and therefore require an efficient I/O subsystem. Data copying and context switching have long been identified as sources of I/O inefficiency. Therefore we propose the new Multimedia Stream System Call (MSSC) mechanism, which is inserted into a Linux kernel: The MSSC mechanism operates in kernel domain with RTP (Real-time Transport Protocol). We present measurements indicating that use of our techniques resulted in a 12.5%∼14% gain in throughput as compared with a conventional Linux system.

• Advances in robotics research
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• v.2 no.1
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• pp.33-44
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• 2018

This paper presents a novel feature detection algorithm called depth-hybrid speeded-up robust features (DH-SURF) augmented by depth information in the speeded-up robust features (SURF) algorithm. In the keypoint detection part of classical SURF, the standard deviation of the Gaussian kernel is varied for its scale-invariance property, resulting in increased computational complexity. We propose a keypoint detection method with less variation of the standard deviation by using depth data from a red-green-blue depth (RGB-D) sensor. Our approach maintains a scale-invariance property while reducing computation time. An RGB-D simultaneous localization and mapping (SLAM) system uses a feature extraction method and depth data concurrently; thus, the system is well-suited for showing the performance of the DH-SURF method. DH-SURF was implemented on a central processing unit (CPU) and a graphics processing unit (GPU), respectively, and was validated through the real-time RGB-D SLAM.

• The KIPS Transactions:PartA
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• v.13A no.5 s.102
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• pp.405-412
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• 2006

Real-time operating systems have been used in various computing environments, where a job must be completed in its deadline, with various conditions, such as effective scheduling policies, the minimum of an interrupt delay, and the solutions of priority inversion problems, that should be perfectly satisfied to design and develop optimal real-time operating systems. Up to now, in order to solve priority inversion problems among several those conditions. There have been two representative protocols: basic priority inheritance protocol and priority ceiling emulation protocol. However, these protocols cannot solve complicated priority inversion problems. In this paper, we design a protocol, called recursive priority inheritance (RPI), protocol that effectively solves the complicated priority inversion problems. Our proposed protocol is also implemented in the Linux kernel and is compared with other existing protocols in the aspect of qualitative analysis.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.7
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• pp.277-282
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• 2013

Recently, there is a growing need for an open software platform where developers easily write intelligent motion control applications for smart cars, smart robots, smart factories, and so on. To this end, a general-purpose operating system with rich functionalities and various hardware supports can be a candidate for such a platform, but it is known to have limitations in guaranteeing the responsiveness of individual applications. In this paper, to assess the suitability of Linux to be such a platform, we evaluate the real-time performance of Xenomai-patched Linux on an ARM-based processor Exynos4210 with motion control applications. Experimental results show that it is possible to stably provide motion cycle times below 1ms to such applications even with background workloads.

• The Journal of the Korea Contents Association
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• v.7 no.1
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• pp.73-82
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• 2007

In recent years, embedded systems have been expanding their application domains from traditional applications (such as defense, robots, and artificial satellites) to portable devices which execute more complicated applications such as cellular phones, digital camcoders, PMPs, and MP3 players. So as to manage restricted hardware resources efficiently and to guarantee both temporal and logical correctness, every embedded system use a real-time operating system (RTOS). Only when the RTOS makes kernel services deterministic in time by specifying how long each service call will take to execute, application programers can write predictable applications. Moreover, so as for an RTOS to be deterministic, its scheduling and context switch overhead should also be predictable. In this paper, we present the complete generalized algorithm to determine the highest priority in the ready list with 22r levels of priorities in a constant time without additional memory overhead.

• Journal of the Korean Data and Information Science Society
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• v.26 no.6
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• pp.1353-1366
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• 2015

These days Shewhart control chart for evaluating stability of the process is widely used in various field. But it must follow strict assumption of distribution. In real-life problems, this assumption is often violated when many quality characteristics follow non-normal distribution. Moreover, it is more serious in multivariate quality characteristics. To overcome this problem, many researchers have studied the non-parametric control charts. Recently, SVDD (Support Vector Data Description) control chart based on RBF (Radial Basis Function) Kernel, which is called K-chart, determines description of data region on in-control process and is used in various field. But it is important to select kernel parameter or etc. in order to apply the K-chart and they must be predetermined. For this, many researchers use grid search for optimizing parameters. But it has some problems such as selecting search range, calculating cost and time, etc. In this paper, we research the efficiency of selecting parameter regions as data structure vary via simulation study and propose a new method for determining parameters so that it can be easily used and discuss a robust choice of parameters for various data structures. In addition, we apply it on the real example and evaluate its performance.

• Journal of Aerospace System Engineering
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• v.7 no.1
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• pp.19-25
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• 2013

Smoothed Particle Hydrodynamics(SPH) method uses a grid of historical analysis and is not Lagrangian particles using the grid method. The Navier-Stokes equations were used to solve the viscous flow of the non-compressed. In this study, the numerical analysis of the three-dimensional Coin Drop Simulation using SPH method was performed, and the analysis results are compared with experimental results, and a similar behavior can be seen. The commercial program used was Abaqus/Explicit. SPH method to reduce the error by comparing the existing flow analysis or interpretation of the continuing research is needed in the future. That will enable real-time analysis of material obtained as a result of these numerical simulations similar to the actual flow phenomena, depending on the development of computer graphics technology to show visually. As a result, this method can be applied to the analysis fluid - structure interaction problems in a variety of fields.