• Journal of the Korean Society for Precision Engineering
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• v.16 no.5 s.98
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• pp.132-144
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• 1999

In this study, the complexity of the product was evaluated quantitatively considering the product structure, assembly process and disassembly process. To evaluate the complexity of the product, subassemblies of automobile were analyzed and then characteristics of part and subassembly were determined according to product structure, assembly process and disassembly process. Evaluation criteria of complexity were determined considering each characteristics of part and subassembly. Experiential evaluation was accomplished by classified evaluation criteria and time-motion evaluation was accomplished by the relational motion factor with characteristics of part and subassembly in MTM(Methods Time Measurement) and WF(Work Factor). The total complexity of product was determined by experiential evaluation and time-motion evaluation.

• Journal of electromagnetic engineering and science
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• v.9 no.4
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• pp.194-201
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• 2009

In this paper, a new spectrum sensing method based on energy detection is proposed and analyzed in a cognitive radio(CR) system. We employ a delay diversity receiver for sensing the primary user's spectrum with reasonable cost and complexity. Conventional CR with the receiver equipping multiple antennas requires additional hardware and space for installing multiple antennas in accordance with increase in the number of antennas. If the number of antennas increases, detection probability as well as hardware complexity and cost rise. Then, it is difficult to make a primary user detector practically. Therefore, we adopt a delay diversity receiver for solving problems of the conventional spectrum detector utilizing multiple antennas. We derive analytical expressions for the spectrum sensing performance of the proposed system. From the simulation results, it is demonstrated that the primary user detector with the delay diversity receiver has almost half the complexity and shows similar or improved performance as compared with that employing multiple antennas. Therefore, the proposed spectrum sensing structure can be a practical solution for enhancing the detection capacity in CR system operations. The results of this paper can be applied to legacy CR systems with simple modifications.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.1
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• pp.113-120
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• 2014

In this paper, I present a new echo canceller using the adaptive cascade system identification (CSI) method, which a system response is divided into several responses so that each response is adaptively estimated and combined. Echo cancellation is required for a dual-duplex DSL, in order to allow each individual loop to operate in a full duplex fashion. Echo cancellation was one of the most difficult aspects of DSL design, requiring high linearity and total echo return loss in excess of 70 dB. Especially, for a fickle response, if the response is estimated by an adaptive filter, the filter needs more taps and the performance is decreased. But the response is divided into several responses, the computation complexities are decreased and the performance is increased. For the stage constant n, which represents the number of stages, if the response is not divided (n=1), the computation complexity of multiply is $2N^2$. And if the response is divided into two responses (n=2), the computation complexity of multiply is $2N^2$. Also, if n=3, the computation complexity is ${\frac{2}{3}}N^2$. Therefore, it is known that the computation complexity is decreased as n is increased. Finally, this proposed method is verified through simulation of echo canceller for digital subscriber line (DSL) application.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.7
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• pp.3433-3446
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• 2019

Aiming at the high complexity of traditional single-channel demodulation algorithm for PCMA signals, a new demodulation algorithm based on neural network is proposed to reduce the complexity of demodulation in the system of non-cooperative PCMA communication. The demodulation network is trained in this paper, which combines the preprocessing module and decision module. Firstly, the preprocessing module is used to estimate the initial parameters, and the auxiliary signals are obtained by using the information of frequency offset estimation. Then, the time-frequency characteristic data of auxiliary signals are obtained, which is taken as the input data of the neural network to be trained. Finally, the decision module is used to output the demodulated bit sequence. Compared with traditional single-channel demodulation algorithms, the proposed algorithm does not need to go through all the possible values of transmit symbol pairs, which greatly reduces the complexity of demodulation. The simulation results show that the trained neural network can greatly extract the time-frequency characteristics of PCMA signals. The performance of the proposed algorithm is similar to that of PSP algorithm, but the complexity of demodulation can be greatly reduced through the proposed algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2537-2543
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• 2014

Between tandem source-channel coding systems and joint source-channel coding systems, it has been known that there is a complexity threshold in complexity versus performance. In this paper, by expanding the previous analysis for equal error protection systems, we analyze and compare the performance under complexity constrains for tandem source-channel coding systems which employ unequal error protection. Under a given complexity constraint, the optimization is performed to minimize the end-to-end distortion of each representative tandem and joint source-channel coding system. The results show that the complexity threshold for unequal error protection systems becomes smaller and the performance enhancement of unequal error protection systems over equal error protection systems gets smaller as the system complexity gets larger.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.3
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• pp.126-132
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• 1996

In this paper, the complexity reduction method for QCELP speech coder (IS-96) without any perfomrance degradation is proposed for the vecoder of CDMA digital cellular system. The energy terms in pitch parameter search and codebook search routines that require large computations are calculated recursively by utilizing the overlapped structure of code vectors in adaptive codebook and excitation codebook. The additional complexity reduction in the codebook search routine can be achieved by using a simple form in calculation of the energy term when the initial codebook value is zero. In the case of lower transmission rates such as 4,2,1 kbps, the complexity reduction by recursive calulations of energy term is increased.

• 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.

• Convergence Security Journal
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• v.10 no.1
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• pp.29-34
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• 2010

It is very important to evaluate the quality of soft wares based on SOA, which develops rapidly. Particularly, one of the most important properties influencing on the quality of system is complexity. Therefore, we propose the metrics for measuring a structural complexity of softwares based on SOA. The proposed metrics is composed of the size of a service, the depth of a service and interdependency from the viewpoint of system structure, and finally we applied the proposed metric to an example.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.459-468
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• 2015

In this paper, we consider an uplink multiuser hybrid beamforming system where an access point (AP) communicates with multiple users simultaneously. The performance of the uplink multiuser hybrid beamforming system depends on the effective channel which is given by the product of the channel matrix and the analog beams. Therefore, to maximize the performance, we need to obtain the channel information and then select the analog beams appropriately by using the acquired channel information. In this paper, we propose the channel estimation method and low complexity analog beam selection algorithm for the uplink multiuser hybrid beamforming system. Additionally, our analysis shows that the proposed low complexity analog beam selection algorithm provides much less complexity than the optimum analog beam selection algorithm. From the numerical results, we confirm that the proposed low complexity analog beam selection algorithm has little performance degradation in spite of much less complexity than the optimum analog beam selection algorithm under the equal system configuration.

• Asia Pacific Journal of Corpus Research
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• v.2 no.1
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• pp.35-45
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• 2021

With the wide spread of the Common European Framework of Reference (CEFR) scales, many studies attempt to apply them in routine teaching and rater training, while more evidence regarding criterial features at different CEFR levels are still urgently needed. The current study aims to explore complexity features that distinguish and predict CEFR proficiency levels in oral performance. Using a quantitative/corpus-based approach, this research analyzed lexical and syntactic complexity features over 80 transcriptions (includes A1, A2, B1 CEFR levels, and native speakers), based on an interview test, Standard Speaking Test (SST). ANOVA and correlation analysis were conducted to exclude insignificant complexity indices before the discriminant analysis. In the result, distinctive differences in complexity between CEFR speaking levels were observed, and with a combination of six major complexity features as predictors, 78.8% of the oral transcriptions were classified into the appropriate CEFR proficiency levels. It further confirms the possibility of predicting CEFR level of L2 learners based on their objective linguistic features. This study can be helpful as an empirical reference in language pedagogy, especially for L2 learners' self-assessment and teachers' prediction of students' proficiency levels. Also, it offers implications for the validation of the rating criteria, and improvement of rating system.