• Journal of KIISE:Computer Systems and Theory
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• v.27 no.5
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• pp.450-463
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• 2000

Array redistribution is usually required to enhance algorithm performance in many parallel programs on distributed memory multicomputers. GEN_BLOCK redistribution, which is redistribution between different GEN_BLOCKs, is essential for load balancing. However, prior research on redistribution has been focused on regular redistribution, such as redistribution between different CYCLIC(N)s. GEN_BLOCK redistribution is very different from regular redistribution. Message passing in regular redistribution involves repetitions of basic message passing patterns, while message passing for GEN_BLOCK redistribution shows locality. This paper proves that two optimal condition, reducing the number of communication steps and minimizing redistribution size, are essential in GEN_BLOCK redistribution. Additionally, by adding a relocation phase to list scheduling, we make an optimal scheduling algorithm for GEN_BLOCK redistribution. To evaluate the performance of the algorithm, we have performed experiments on a CRAY T3E. According to the experiments, it was proven that the scheduling algorithm shows better performance and that the conditions are critical in enhancing the communication speed of GEN_BLOCK redistribution.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.09a
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• pp.21-50
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• 1997

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.12
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• pp.4567-4583
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• 2021

This study proposes an analytical approximation algorithm based on extreme value theory (EVT) for the inverse of the power of the incomplete Gamma function. First, the Gumbel function is used to approximate the power of the incomplete Gamma function, and the corresponding inverse problem is transformed into the inversion of an exponential function. Then, using the tail equivalence theorem, the normalized coefficient of the general Weibull distribution function is employed to replace the normalized coefficient of the random variable following a Gamma distribution, and the approximate closed form solution is obtained. The effects of equation parameters on the algorithm performance are evaluated through simulation analysis under various conditions, and the performance of this algorithm is compared to those of the Newton iterative algorithm and other existing approximate analytical algorithms. The proposed algorithm exhibits good approximation performance under appropriate parameter settings. Finally, the performance of this method is evaluated by calculating the thresholds of space-time block coding and space-frequency block coding pattern recognition in multiple-input and multiple-output orthogonal frequency division multiplexing. The analytical approximation method can be applied to other related situations involving the maximum statistics of independent and identically distributed random variables following Gamma distributions.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.755-758
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• 2001

In this paper. Ive propose a postprocessing technique based on the theory of projection on convex sets(POCS) to reduce the blocking artifacts in HDTV decoded images. In BDCT of HDTV. the image is divided into a grid of non-overlapped 8 ${\times}$ 8 blocks. and then each block is coded separately. A block which is located one pixel apart from the grid of BDCT will include the boundary of the original 8 ${\times}$ 8 block. If the blocking artifact is Introduced alone the block boundary. this block will have different frequency characteristic from that of the original block. Thus, a comparison of frequency characteristics of these two overlapping blocks can detect the undesired high-frequency components mainly caused by the blocking artifact. By eliminating these undesired high-frequency components adaptively, robust smoothing projection operator can be obtained. Simulation results with real image sequences indicate that the proposed method performs better than conventional algorithms.

• Computational Structural Engineering
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• v.9 no.1
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• pp.55-64
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• 1996

Sloshing frequencies of the fluid in rectangular tanks with a bottom-mounted rectangular block are determined by linear water wave theory. Velocity potential is decomposed into those for the wall-induced waves, and the reflected, transmitted, and scattered waves by the block. The reflection and transmission coefficients are determined using the continuity conditions of mass flux and energy flux on the common vertical boundaries of the fluid regions, and the boundary conditions on the both sides of the block. The analysis results indicate that the sloshing frequencies reduce, as the block becomes tall and vade and as the block moves toward the center. The variations of the sloshing frequencies due to the block are found to be more sensitive in broad thanks than is tall tanks.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.863-866
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• 1998

In this paper, we proposes Moving Picture Compression reducing bit numbers within the block by probability in 3D-DCT considered of temporal axis. From Delta Modification theory for frequency components, bit numbers within the block(4$\times$4) were properly compressed by using the Probability Entropy. At the result for the proposed algorithm, we could find that the values of PSNR for resolution and the compression rate were better than existing methods.

• Geomechanics and Engineering
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• v.12 no.4
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• pp.723-738
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• 2017

Rock is a heterogeneous material, which introduces complexity in the analysis of rock slopes, since both the existing discontinuities within the rock mass and the intact rock contribute to the degradation of strength. Rock failure is often catastrophic due to the brittle nature of the material, involving the sliding along structural planes and the fracturing of rock bridge. This paper proposes an advanced discretization method of rock mass based on block theory. An in-house software, GeoSMA-3D, has been developed to generate the discrete fracture network (DFN) model, considering both measured and artificial joints. Measured joints are obtained from the photogrammetry analysis on the excavation face. Statistical tools then facilitate to derive artificial joints within the rock mass. Key blocks are searched to provide guidance on potential reinforcement measures. The discretized blocky system is subsequently implemented into a discontinuous deformation analysis (DDA) code. Strength reduction technique is employed to analyze the stability of the slope, where the factor of safety can be obtained once excessive deformation of slope profile is observed. The combined analysis approach also provides the failure mode, which can be used to guide the choice of strengthening strategy if needed. Finally, an illustrated example is presented for the analysis of a rock slope of 20 m height inclined at $60^{\circ}$ using combined GeoSMA-3D and DDA calculation.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.5
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• pp.529-539
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• 2000

This paper proposes a prefetch-based disk buffer management algorithm, which we call W2R (Veighingjwaiting Room). Instead of using elaborate prefetching schemes to decide which blockto prefetch and when, we simply follow the LRU-OBL (One Block Lookahead) approach and prefetchthe logical next block along with the block that is being referenced. The basic difference is that theW2R algorithm logically partitions the buffer into two rooms, namely, the Weighing Room and theWaiting Room. The referenced, hence fetched block is placed in the Weighing Room, while theprefetched logical next block is placed in the Waiting Room. By so doing, we alleviate some inherentdeficiencies of blindly prefetching the logical next block of a referenced block. Specifically, a prefetchedblock that is never used may replace a possibly valuable block and a prefetched block, thoughreferenced in the future, may replace a block that is used earlier than itself. We show through tracedriven simulation that for the workloads and the environments considered the W2R algorithm improvesthe hit rate by a maximum of 23.19 percentage points compared to the 2Q algorithm and a maximumof 10,25 percentage feints compared to the LRU-OBL algorithm.

• The Korean Journal of Financial Management
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• v.22 no.1
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• pp.119-146
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• 2005

This study applies extreme value theory to get extreme value-VAR for Korean Stock market and showed the usefulness of the approach. Block maxima model and POT model were used as extreme value models and tested which model was more appropriate through back testing. It was shown that the block maxima model was unstable as the variation of the estimate was very large depending on the confidence level and the magnitude of the estimates depended largely on the block size. This shows that block maxima model was not appropriate for Korean Stock market. On the other hand POT model was relatively stable even though extreme value VAR depended on the selection of the critical value. Back test also showed VAR showed a better result than delta VAR above 97.5% confidence level. POT model performs better the higher the confidence level, which suggests that POT model is useful as a risk management tool especially for VAR estimates with a confidence level higher than 99%. This study picks up the right tail and left tail of the return distribution and estimates the EVT-VAR for each, which reflects the asymmetry of the return distribution of the Korean Stock market.

• Information Systems Review
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• v.21 no.3
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• pp.27-47
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• 2019

The purpose of this study is to propose a conceptual model for the tourism application of the block chain consensus construct and to test the intention of technology acceptance of potential consumers. First, we have tried to investigate the security, reliability, functionality was derived. Secondary, structural validation of the proposed model confirmed the factors influencing the acceptance of block chain technology in terms of consumers. Based on this, we apply the Unified Theory of Acceptance and Use of Technology to evaluate. Individual innovation and block-chain technology have a strong causal relationship with the proposed block chain acceptance intentions based on the Hybrid Block Chain Consensus system, which shows strong innovation and strong cognitive status. In addition, the factors directly affecting the acceptance of block-chain are the benefits expected from the block chain, the technical infrastructure required to use the service, the perceived benefits available. The influence of the surrounding environment on the adoption of technology and ease of use on new technology did not affect the acceptance intention significantly.