• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.3
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• pp.128-135
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• 2010

Recently complexity of embedded software cause to be used real-time operating system (RTOS) to implement various functions in the embedded system. And also, according to requirement of complex functions in embedded systems, the number as well as complexity of tasks get increased continuously. In case that many tasks collaborated in a microprocessor, context switching time between tasks is a overhead waisting a CPU resource. Therefore the time of task context switching is an important factor that affects performance of RTOS. In this paper, we concentrate on the improvement of task context switch for reducing overhead and achieving fast response time in RTOS. To achieve these goal, we suggest multiple register files and task context switching algorithm. By reducing the context switch overhead, we try to ease scheduling and assure fast response times in multitasking environment. As a result, the context switch overhead decreased by 8~16% depend on the number of register files, and some task set which are not schedulable with single register file are schedulable due to that decrease with multiple register files.

• Journal of International Society for Simulation Surgery
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• v.2 no.2
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• pp.64-66
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• 2015

Purpose : In this paper we proposed cascade feature filter and projection method for rapid human face recognition for the large-scale high-dimensional face database. Materials and Methods : The relevant features are selected from the large feature set using Fast Correlation-Based Filter method. After feature selection, project them into discriminant using Principal Component Analysis or Linear Discriminant Analysis. Their cascade method reduces the time-complexity without significant degradation of the performance. Results : In our experiments, the ORL database and the extended Yale face database b were used for evaluation. On the ORL database, the processing time was approximately 30-times faster than typical approach with recognition rate 94.22% and on the extended Yale face database b, the processing time was approximately 300-times faster than typical approach with recognition rate 98.74 %. Conclusion : The recognition rate and time-complexity of the proposed method is suitable for real-time face recognition system on the large-scale high-dimensional face database.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.498-503
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• 2009

As for Hadamard Transform, because the calculation time of this transform is slower than Discrete Cosine Transform (DCT) and Fast Fourier Transform (FFT), the effectiveness and the practicality are insufficient. Then, the computational complexity can be decreased by using the butterfly operation as well as FFT. We composed calculation time of FFT with that of Fast Complex Hadamard Transform by constructing the algorithm of Fast Complex Hadamard Transform. They are indirect conversions using program of complex number calculation, and immediate calculations. We compared calculation time of them with that of FFT. As a result, the reducing the calculation time of the Complex Hadamard Transform is achieved. As for the computational complexity and calculation time, the result that quadrinomial Fast Complex Hadamard Transform that don't use program of complex number calculation decrease more than FFT was obtained.

• Journal of the Korea Society of Computer and Information
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• v.20 no.9
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• pp.81-86
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• 2015

This paper suggests heuristic algorithm with linear time complexity to decide the normal and optimal point at minimum loss/maximum profit maximum shortest scheduling problem with additional loss cost and bonus profit cost. This algorithm computes only the earliest ending time for each node. Therefore, this algorithm can be get the critical path and project duration within O(n) time complexity and reduces the five steps of critical path method to one step. The proposed algorithm can be show the result more visually than linear programming and critical path method. For real experimental data, the proposed algorithm obtains the same solution as linear programming more quickly.

• The Journal of the Korea Contents Association
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• v.18 no.11
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• pp.484-492
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• 2018

This study examined the effects of field complexity and type of target objects on the performance in baggage screening task. A total of 62 participants(male: 45.2%, female: 54.8%) participated and their mean age was 22.88. The simulated baggage screening task was developed for this study and after the orientation and task exercises, main experiment session was conducted. Participants performed a total of 200 tasks and 40(20%) contained target object. The complexity was set at three levels: high, middle, and low levels and the number of background items contained 20, 14. and 8 respectively. The type of target was set as gun, knife, liquid, and righter. The dependent variables were hit ratio and reaction time. The results showed that the hit ratio decreased and reaction time increased significantly as field complexity increased, and they varied depending on the type of target. The hit ratio of the knife was the highest and liquid lowest and reaction time of the knife was the fastest and liquid slowest. In addition, the interaction effect was also significant. Knife was not affected by complexity, however, small item such as lighter was most affected by complexity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8C
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• pp.1047-1054
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• 2004

In this paper, we present two systolic arrays for computing multiplications in CF(2$\^$m/) generated by an irreducible all one polynomial (AOP). The proposed two systolic mays have parallel-in parallel-out structure. The first systolic multiplier has area complexity of O(㎡) and time complexity of O(1). In other words, the multiplier consists of m(m+1)/2 identical cells and produces multiplication results at a rate of one every 1 clock cycle, after an initial delay of m/2+1 cycles. Compared with the previously proposed related multiplier using AOP, our design has 12 percent reduced hardware complexity and 50 percent reduced computation delay time. The other systolic multiplier, designed for cryptographic applications, has area complexity of O(m) and time complexity of O(m), i.e., it is composed of m+1 identical cells and produces multiplication results at a rate of one every m/2+1 clock cycles. Compared with other linear systolic multipliers, we find that our design has at least 43 percent reduced hardware complexity, 83 percent reduced computation delay time, and has twice higher throughput rate Furthermore, since the proposed two architectures have a high regularity and modularity, they are well suited to VLSI implementations. Therefore, when the proposed architectures are used for GF(2$\^$m/) applications, one can achieve maximum throughput performance with least hardware requirements.

• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.30-37
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• 2010

Many embedded real - lime systems have adopted processors supported with dynamic voltage scal-ing(DVS) recently. Power is one of the important metrics for Optimization in the design and operation of embedded real-time systems. We can save considerable energy by using slowdown of processor sup-ported with DVS. In this paper, we improved the previous algorithm at a point of view of time complexity to calculate task slowdown factors for an efficient energy consumption in embedded real-time systems with task synchronization. We grasped the properties of the previous algorithm having $O(n^{2})$ time complexity through mathematical analysis and s simulation. Using its properties we proposed the improved algorithms with O(nlogn) and O(n) time complexity which have the same performance as the previous algorithm has.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.168-172
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• 2015

In this paper, a balanced bitrate control in transcoding process based on video complexity measure for multi-view system which simultaneously shows multiple channels or video contents in single screen, is proposed. In order to consider the total quality of multiple video streams, the proposed algorithm reduces the complexity of multiple video stream and video quality differences at the same time by controlling bitrates of each stream by weighting when they are stitched for single screen. For the measure of complexity and quality differences between video streams, two different data: histogram of macroblock type and bitrate for each stream are used. The experimental result indicates that proposed algorithm decreases fluctuation of quality difference between videos in the multi-view system.

• Journal of Communications and Networks
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• v.16 no.6
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• pp.620-626
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• 2014

In this paper, we propose a parallel collaborative sphere decoder with a scalable architecture promising quasi-maximum likelyhood performance with a relatively small amount of computational resources. This design offers a hardware-friendly algorithm using a modified node operation through fixing the variable complexity of the critical path caused by the sequential nature of the conventional sphere decoder (SD). It also reduces the computational complexity compared to the fixed-complexity sphere decoder (FSD) algorithm by tree pruning using collaboratively operated node operators. A Monte Carlo simulation shows that our proposed design can be implemented using only half the parallel operators compared to the approach using an ideal fully parallel scheme such as FSD, with only about a 7% increase of the normalized decoding time for MIMO dimensions of $16{\times}16$ with 16-QAM modulation.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.1
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• pp.27-36
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• 2000

We perform a computational complexity analysis of a heuristic algotithm proposed in the literature for the combinatorial optimization problems extended with a single side-constraint. This algorithm, although such a view was not given in the original work, is a disguised version of an optimal Lagrangian dual solution technique. It also has been observed to be a very efficient heuristic producing near-optimal solutions for the primal problems in some experiments. Especially, the number of iterations grows sublinearly in terms of the network node size so that the heuristic seems to be particularly suitable for the applicatons such as routing with semi-real time requirements. The goal of this paper is to establish a polynomal worst-case complexity of the algorithm. In particular, the obtained complexity bound suports the sublinear growth of the required iterations.