• Journal of Digital Contents Society
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• v.9 no.4
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• pp.543-550
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• 2008

There exist many QoS problems such as delay and jitter for mobile streaming due to limited bandwidth. This paper proposed a transaction update method based on Fuzzy chunk to solve the problems. The proposed method updated a transaction, which is classified as a read or an update, using Fuzzy filtering. A chunk block is rearranged according to the fuzziness which is classified as better relevance for fuzziness greater than 0.8, relevance for fuzziness between 0.5 and 0.7, and less irrelevance for fuzziness less than 0.5. According to the simulation result for the rearranged chunk block, the proposed method has better performance than those of RBM(Randon Based method), DBM(Distance Based Method), and FBM(Frequency Based Method).

• Journal of Ocean Engineering and Technology
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• v.11 no.1
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• pp.96-96
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• 1997

This paper presents a Inertial Measuring Unit(IMU) for motion measurement of an AUV. The IMU is composed of three parts: inertial sensors with three servo accelerometers and three rate gyros, an analog/digital interface board, and a signal processing board with TMS320C31 DSP processor. The IMU is a class of strap-down inwetial navigation system does not applicable directly to the navigation system in consequence of the AUV and integrated sensors for an integrated navigation system of the AUV. Fast calculstion of direction cosine matrix for the coordinate transformation body to reference is obtained through the DSP processor. A switching algotrithm is used to lessen the low frequency drift effect of the gyros in the vertical plane with use of low pass filtering of the signal of the accelerometers.

• Journal of Korean Library and Information Science Society
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• v.29
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• pp.105-140
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• 1998

This is a way of establishing the information sovereignty in the industrial knowledge of society. The occurrence of the industrial knowledge of society builds knowledge and information as digital system. Digitalized knowledge and information has some characteristics of which the information should be light and variable, so that it can be transmitted rapidly. At this moment, if information super highway is built, and the digitalized information of the advanced information country comes to us, we are to get easily information dependence unless we are ready. Nowadays, our country is accepting the knowledge and information of the advanced information countries without filtering it properly. What is the reason? This means that we are lack of traditional knowledge resourses as the foundation of digital system. This paper deals with (1) the historical reason of the lackness of the traditional knowledge resourses, (2) the aspect of the consumer culture about knowledge and information, and (3) the aspect of the production culture about the knowledge and information. In order to overcome the information dependence, in this paper, we should change both production and consumption of our knowledge and information into a new pattern, establish the seed knowledge resourses, and build libraries everywhere we can use easily. For this case study, this paper takes examples of maeul (which may mean traditional villiage in Korea.) libraries on Changwon City.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1833-1842
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• 2016

In grid-connected converter control, grid voltage feedforward is usually introduced to suppress the influence of grid voltage distortion on the converter's grid-side AC current. However, owing to the time-delay in control systems, the suppression effect of the grid voltage distortion is seriously affected. In this paper, the positive effects of the grid voltage feedforward control are analyzed in detail, and the time-delay caused by the low-pass filter (LPF) in the voltage filtering circuits and digital control are summarized. In order to reduce the time-delay effect on the performance of the feedforward control, a voltage feedforward control strategy with time-delay compensation is proposed, in which, a leading correction of the feedforward voltage is used. The optimal leading step used in this strategy is derived from analyzing the phase-frequency characteristics of a LPF and the implementation of digital control. By using the optimal leading step, the delay in the feedforward path can be further counteracted so that the performance of the feedforward control in terms of suppressing the influence of grid voltage distortion on the converter output current can be improved. The validity of the proposed method is verified through simulation and experiment results.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.9 no.2
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• pp.103-113
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• 1991

The accuracy of input coordinates of ground control points and check points affects great influences to the results of ground coordinate computation in using SPOT digital image data. The original SPOT images displayed on CRT are not usually adequate for identifying the object features and determining the point positioning. Hence, appropriate image processing techniques such as contrast enhancement, subpixel interpolation, edge enhancement, and spatial filtering are needed. In this study, the principles of digital image processing needed for accurate three dimensional positioning and spectral characteristic analysis are investigated. The algorithms for the actual applications are developed and programmed. And using the developed image processing software, some SPOT P-mode and XS-mode images are merged into the SPOT P＋XS, the high-resolution color composite image.

• Economic and Environmental Geology
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• v.18 no.1
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• pp.41-47
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• 1985

The filtering ability of $J_0$ and $J_1$ digital linear filters is compared by means of an adaptive linear filter. Any $J_0$ domain Hankel transform integral can be transformed mathematically into its corresponding $J_1$ domain integral. The apparent resistivities for any electrode configuration employed in resistivity soundings can be evaluated with a single $J_1$ filter. The $J_1$ filter usually has similar accuracy to, but shorter length than, the corresponding $J_0$ filter. The domain transformation from $J_0$ to $J_1$ enables us to use effective expressions of apparent resistivity, involving $J_1$ alone, not only for Schlumberger but also for dipole-dipole array.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.265-268
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• 2004

At these days, electronic maritime chart is in positively using various fields. But most of electronic maritime chart and topography information system is hard to using various fields despite that demand because that difficult approach from separately and specific constitution. This thesis apply to image filtering that extract requirement topography data from simplification of the whole system. And as constructing database of simple structure that getting various information from sounding depth and existing database, propose electronic maritime chart system to practicable 3D embodiment. And also propose convenience and commonplace to simple process about frequently renewal.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.4
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• pp.87-97
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• 2009

Internet network routing system is used to prevent spread and distribution of malicious data traffic. This study is based on analysis of diagnostic weakness structure in the network security domain. We propose an improved integrated multi-level protection domain for in the internal route of groupware. This paper's protection domain is designed to handle the malicious data traffic in the groupware and finally leads to lighten the load of data traffic and improve network security in the groupware. Infrastructure of protection domain is transformed into five-stage blocking domain from two or three-stage blocking. Filtering and protections are executed for the entire server at the gateway level and internet traffic route ensures differentiated protection by dividing into five-stage. Five-stage multi-level network security domain's malicious data traffic protection performance is better than former one. In this paper, we use a trust evaluation metric for measuring the security domain's performance and suggested algorithm.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.4
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• pp.15-22
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• 2011

U-Healthcare service is a real-time service using the vital signs which are continuously transferred from monitoring sensors attached to mobile patients under the wireless network environments. It should monitor the health condition of mobile patients everywhere at any time. In this paper, we have improved two features of the three layered mobile patient monitoring system with load balancing ability. First, the simulation process has been improved by allowing the number of related nodes to be changed. Secondly, we have modified S node to which queue is added to reduce the loss rate of collecting data from patients during the delay of S node process. And the data from the patient with high priority can be transferred to the server immediately through the filtering function. Furthermore, we have solved the problem of redundancy in sharing information among S nodes by differentiating process time to each S node. By performing a DEVS Java-based system simulation, we have verified the efficiency of this improved system.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.4
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• pp.119-131
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• 2011

In this paper, we explore the application of 2-D dual-tree discrete wavelet transform (DDWT), which is a directional and redundant transform, for image coding. DDWT main property is a more computationally efficient approach to shift invariance. Also, the DDWT gives much better directional selectivity when filtering multidimensional signals. The dual-tree DWT of a signal is implemented using two critically-sampled DWTs in parallel on the same data. The transform is 2-times expansive because for an N-point signal it gives 2N DWT coefficients. If the filters are designed is a specific way, then the sub-band signals of the upper DWT can be interpreted as the real part of a complex wavelet transform, and sub-band signals of the lower DWT can be interpreted as the imaginary part. The quincunx lattice is a sampling method in image processing. It treats the different directions more homogeneously than the separable two dimensional schemes. Quincunx lattice yields a non separable 2D-wavelet transform, which is also symmetric in both horizontal and vertical direction. And non-separable wavelet transformation can generate sub-images of multiple degrees rotated versions. Therefore, non-separable image processing using DDWT services good performance.