• The Transactions of the Korea Information Processing Society
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• v.7 no.6
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• pp.1737-1745
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• 2000

In the last decade, considerable research effort has been studied ot multi-dimensional GIS and many spatiotemporal operations and query languages have been proposed. Many of them have focused on designing of operation, which process with data that is valid at current point in time. But, research that studied to updata operation that updates or inserts the past data is very rare. This paper designs an update operation and an insertion operation for integrity of past data of multi-dimensional GIS, and propose a new data model for efficient processing of the operations.

• Journal of Korea Multimedia Society
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• v.12 no.2
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• pp.165-177
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• 2009

Embedded database systems (EDBMS) based on NAND flash memories are widely adopted for logging data on sensor nodes. Since write and erase operations of a flash memory are time consuming compared to read operations and wear memory cells, it is important to reduce these operations to enhance the EDBMS performance and to extend the memory life. In this paper, we propose a delayed write scheme to archive this goal. Proposed scheme stores updated parts of database pages into delayed write records to reduce the database page writes. By doing that, it decreases write and erase operations on a flash memory. Therefore, the proposed scheme enhances the logging performance of a write-intensive EDBMS on a sensor node and extends the flash memory life.

• Journal of IKEEE
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• v.3 no.2 s.5
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• pp.276-284
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• 1999

In this paper, we propose a new technique which allows to store the pre-scaling constants directly in a table thus eliminating the cycle for computing pre-scaling constants. Especially we analyzed the range of pre-scalingconstants and rearranged them in a carry-save form using two look-up tables so that the size of the tables can be reduced significantly. The resulting scheme is compared with the previously developed method and shown to be effective with respect to area and time to implement the high-radix divider.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.7
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• pp.12-18
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• 2017

This paper presents a Dijkstra's-search-based sphere decoding (SD) algorithm with limited complexity for the symbol detection in MIMO communication systems. The Dijkstra search-based SD is efficient to achieve a near-optimal error rate in the MIMO symbol detection, but has a critical problem in that its complexity is variable and can correspond to that of the exhaustive search in the worst case. The proposed algorithm limits the computations while achieving a near-optimal error rate. Simulation results show that the error rate is near optimal even with the limited complexity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3C
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• pp.322-328
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• 2009

This paper proposes new simplified sum-product (SSP) decoding algorithm to improve BER performance for low-density parity-check codes. The proposed SSP algorithm can replace multiplications and divisions with additions and subtractions without extra computations. In addition, the proposed SSP algorithm can simplify both the In[tanh(x)] and tanh-1 [exp(x)] by using two quantization tables which can reduce tremendous computational complexity. Moreover, the simulation results show that the proposed SSP algorithm can improve about $0.3\;{\sim}\;0.8\;dB$ of BER performance compared with the existing modified sum-product algorithms.

• Journal of Broadcast Engineering
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• v.18 no.5
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• pp.669-679
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• 2013

This paper proposed a new VLSI (Very Large Scale Integrated Circuit) architecture for stereo matching in real time. We minimized the amount of calculation and the number of memory accesses through analyzing calculation of stereo matching. From this, we proposed a new stereo matching calculating cell and a new hardware architecture by expanding it in parallel, which concurrently calculates cost function for all pixels in a search range. After expanding it, we proposed a new hardware architecture to calculate cost function for 2-dimensional region. The implemented hardware can be operated with minimum 250Mhz clock frequence in FPGA (Field Programmable Gate Array) environment, and has the performance of 805fps in case of the search range of 64 pixels and the image size of $640{\times}480$.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.1 no.1
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• pp.10-16
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• 2002

In this paper, a novel algorithm for segmentation of moving multiple vehicles in video sequences using logic operations is proposed. For the case of multiple vehicles in a scene, the proposed algorithm begins with a robust double-edge image derived from the difference between two successive frames using exclusive OR operation. After extracting only the edges of moving multiple vehicles using Laplacian filter, AND operation and dilation operation, the image is segmented into moving multiple vehicle image. The features of moving vehicles can be directly extracted from the segmented images. The proposed algorithm has no the two preprocessing steps, so it can reduce noises which are norm at in preprocessing of the original images. The algorithm is more simplified using logic operations. The proposed algorithm is evaluated on an outdoor video sequence with moving multiple vehicles in 90,000 frames of 30fps by a low-end video camera and produces promising results.

• The Transactions of the Korea Information Processing Society
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• v.2 no.5
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• pp.634-644
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• 1995

In this paper, we propose a mechanism to transform more effective and semantically equivalent queries by using appropriately represented three kinds of knowledge. Also we proposed a mechanism which transforms partially omitted components or expressions into complete queries so that users can use more simple queries. The knowledges used to transform and optimize are semantic, structural and domain knowledge. Semantic knowledge includes semantic integrity constraints and domain integrity constraints. Structural knowledge represents physical relationship between relations. And domain knowledge maintains the domain information of attributes. The proposed system optimizes to more effective queries by eliminating/adding/replacing unnecessary or redundant restrictions/joins.

• The Transactions of the Korea Information Processing Society
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• v.7 no.1
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• pp.252-265
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• 2000

In this thesis, the analysis of data processing method and the amount of computation in the whole geometry processing is conducted step by step. Floating-point ALU design is based on the characteristics of geometry processing operation. The performance of the devised ALU fitting with the geometry processing operation is analyzed by simulation after the description of the proposed ALU and geometry processor. The ALU designed in the paper can perform three types of floating-point operation simultaneously-addition/subtraction, multiplication, division. As a result, the 23.5% of improvement is achieved by that floating-point ALU for the whole geometry processing and in the floating-point division and square root operation, there is another 23% of performance gain with adding area-performance efficient SRT divisor.

• Journal of IKEEE
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• v.19 no.4
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• pp.590-595
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• 2015

This paper proposes a design of efficient hierarchy structure in the tile based rasterizer. The proposed hierarchy structure avoids unnecessary calls of low level tile at which a calculation is not required. A low level tile is classified into three categories based on its maximum, minimum position, and inside outside test. The necessity of calculations on the corresponding low level tile can be determined by its classification. The overall amount of computations for graphic processing can be reduced by not calling for the low level tile with no calculation. The proposed hierarchy structure can reduce an execution time of graphic processing. It shows higher efficiency with the more vertex density of formulating 3D model.