• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.10
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• pp.4214-4230
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• 2020

This paper introduces a pilot allocation scheme for massive MIMO systems based on deep convolutional neural network (CNN) learning. This work is an extension of a prior work on the basic deep learning framework of the pilot assignment problem, the application of which to a high-user density nature is difficult owing to the factorial increase in both input features and output layers. To solve this problem, by adopting the advantages of CNN in learning image data, we design input features that represent users' locations in all the cells as image data with a two-dimensional fixed-size matrix. Furthermore, using a sorting mechanism for applying proper rule, we construct output layers with a linear space complexity according to the number of users. We also develop a theoretical framework for the network capacity model of the massive MIMO systems and apply it to the training process. Finally, we implement the proposed deep CNN-based pilot assignment scheme using a commercial vanilla CNN, which takes into account shift invariant characteristics. Through extensive simulation, we demonstrate that the proposed work realizes about a 98% theoretical upper-bound performance and an elapsed time of 0.842 ms with low complexity in the case of a high-user-density condition.

• The Journal of Industrial Distribution & Business
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• v.9 no.11
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• pp.17-24
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• 2018

Purpose - The portability, functionality, and convenience of smart phones are constantly updated. With the rapid popularization of users of mobile terminals, Xiaomi is also developing rapidly. In February 2015, the users of Xiaomi exceeded 100 million people. As a transnational industry, Xiaomi has developed rapidly in not only China but also Korea. However, through the literature review, there is no radmissible study on the Xiaomi mobile telephones in the Korean market, so it is necessary to study the Xiaomi mobile phones in Korean market. Research design, data, and methodology - Figure analysis of data and social science analytical software of IBM SPSS AMOS 23.0 and IBM Statistics 23.0 were used for all the data researched. Results - First, the innovative diffusion temperament and the compatibility of Xiaomi have positive impacts on achievement expectations and effort expectations. Second, the innovative diffusion temperament and the complexity of Xiaomi have negative impacts on achievement expectations and effort expectations. Third, the innovative diffusion characteristics and the relative superiority of Xiaomi have positive impacts on achievement expectations and effort expectations. Conclusions - Through the analysis of the prior study, the innovation acceptance characteristics consist of compatibility, complexity, relative superiority, observation possibility, and the attempt possibility; the technical acceptance characteristics consist of achievement expectations, effort expectations, social influence, promotion condition, the study conducts relevant research on the continued use intention and analyze the hypothesis of research model.

• ETRI Journal
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• v.38 no.6
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• pp.1240-1249
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• 2016

With the number of IP cores in a multicore system-on-chip increasing to up to tens or hundreds, the role of on-chip interconnection networks is vital. We propose a networks-on-chip-style bus network as a compromise and redefine the exploration problem to find the best IP tiling patterns and communication path combinations. Before solving the problem, we estimate the time complexity and validate the infeasibility of the solution. To reduce the time complexity, we propose two fast exploration algorithms and develop a program to implement these algorithms. The program is executed for several experiments, and the exploration time is reduced to approximately 1/22 and 7/1,200 at the first and second steps of the exploration process, respectively. However, as a trade-off for the time saving, the time cost (TC) of the searched architecture is increased to up to 4.7% and 11.2%, respectively, at each step compared with that of the architecture obtained through full-case exploration. The reduction ratio can be decreased to 1/4,000 by simultaneously applying both the algorithms even though the resulting TC is increased to up to 13.1% when compared with that obtained through full-case exploration.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.4
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• pp.419-426
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• 2014

This paper proposes a high-throughput encoding process and encoder architecture for quasi-cyclic low-density parity-check codes in IEEE 802.11ac standard. In order to achieve the high throughput with low complexity, a partially parallel processing based encoding process and encoder architecture are proposed. Forward and backward accumulations are performed in one clock cycle to increase the encoding throughput. A low complexity cyclic shifter is also proposed to minimize the hardware overhead of combinational logic in the encoder architecture. In IEEE 802.11ac systems, the proposed encoder is rate compatible to support various code rates and codeword block lengths. The proposed encoder is implemented with 130-nm CMOS technology. For (1944, 1620) irregular code, 7.7 Gbps throughput is achieved at 100 MHz clock frequency. The gate count of the proposed encoder core is about 96 K.

• The Transactions of the Korea Information Processing Society
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• v.2 no.3
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• pp.314-323
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• 1995

Recently, as users' understanding about software is raised, software developers devoted all their energy to satisfy users' needs. Accordingly, software is getting increase in volume and becoming complicated. As account of it, development and maintenance costs of software have been increased, and a large number of developers were projected in maintenance and development of new software. Software with good maintenability has a function in a module and is easy to read and simple. In this paper, for effective management of software complexity, I designed and implemented the system which accepts source program by input and measures product metrics and produce measurement value of factor items.

• ETRI Journal
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• v.38 no.1
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• pp.100-111
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• 2016

This paper presents a low-complexity channel-adaptive reconfigurable $4{\times}4$ QR-decomposition and M-algorithm-based maximum likelihood detection (QRM-MLD) multiple-input and multiple-output (MIMO) detector. Two novel design approaches for low-power QRM-MLD hardware are proposed in this work. First, an approximate survivor metric (ASM) generation technique is presented to achieve considerable computational complexity reduction with minor BER degradation. A reconfigurable QRM-MLD MIMO detector (where the M-value represents the number of survival branches in a stage) for dynamically adapting to time-varying channels is also proposed in this work. The proposed reconfigurable QRM-MLD MIMO detector is implemented using a Samsung 65 nm CMOS process. The experimental results show that our ASM-based QRM-MLD MIMO detector shows a maximum throughput of 288 Mbps with a normalized power efficiency of 10.18 Mbps/mW in the case of $4{\times}4$ MIMO with 64-QAM. Under time-varying channel conditions, the proposed reconfigurable MIMO detector also achieves average power savings of up to 35% while maintaining a required BER performance.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.3
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• pp.291-301
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• 2012

A scalar metric for the assessment of hull surface producibility was known to be useful in estimating the complexity of a hull form of ships or large offshore structures by looking at their shape. However, it could not serve as a comprehensive measuring tool due to its lack of important components of the hull form such as longitudinals, stiffeners, and web frames attached to the hull surface. To have a complete metric for cost estimation, these structural members must be included. In this paper, major inner structural members are considered by measuring the complexity of their geometric shape. The final scalar metric thus consists of the classes containing inner members with various curvature magnitudes as well as the classes containing curved plates with single and double curvature distribution. Those two distinct metrics are merged into a complete scalar metric that accounts for the total cost estimation of complex structural bodies.

• Journal of Communications and Networks
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• v.18 no.1
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• pp.84-94
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• 2016

Design of effective cooperative jamming (CJ) algorithm is studied in this paper to maximize the achievable secrecy rate when the total transmit power of the source and multiple trusted terminals is constrained. Recently, the same problem was studied in [1] and an optimal algorithm was proposed involving a one-dimensional exhaustive searching.However, the computational complexity of such exhaustive searching could be very high, which may limit the practical use of the optimal algorithm. We propose an asymptotically optimal algorithm, involving only a fast line searching, which can guarantee to achieve the global optimality when the total transmit power goes to infinity. Numerical results demonstrate that the proposed asymptotically optimal algorithm essentially gives the same performance as the algorithm in [1, (44)] but with much lower computational complexity.

• Journal of Information Technology Services
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• v.9 no.4
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• pp.219-229
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• 2010

The Green's equivalence relations have played a fundamental role in the development of semigroup theory. They are concerned with mutual divisibility of various kinds, and all of them reduce to the universal equivalence in a group. Boolean matrices have been successfully used in various areas, and many researches have been performed on them. Studying Green's relations on a monoid of boolean matrices will reveal important characteristics about boolean matrices, which may be useful in diverse applications. Although there are known algorithms that can compute Green relations, most of them are concerned with finding one equivalence class in a specific Green's relation and only a few algorithms have been appeared quite recently to deal with the problem of finding the whole D or J equivalence relations on the monoid of all $n{\times}n$ Boolean matrices. However, their results are far from satisfaction since their computational complexity is exponential-their computation requires multiplication of three Boolean matrices for each of all possible triples of $n{\times}n$ Boolean matrices and the size of the monoid of all $n{\times}n$ Boolean matrices grows exponentially as n increases. As an effort to reduce the execution time, this paper shows an isomorphism between the R relation and L relation on the monoid of all $n{\times}n$ Boolean matrices in terms of transposition. introduces theorems based on it discusses an improved algorithm for the J relation computation whose design reflects those theorems and gives its execution results.

• Journal of the Semiconductor & Display Technology
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• v.20 no.3
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• pp.71-76
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• 2021

Digital decimation filters are used in various digital signal processing systems using ADCs, including digital communication systems and sensor network systems. When the sampling rate of digital data is reduced, aliasing occurs. So, an anti-aliasing filter is necessary to suppress aliasing before down-sampling the data. Since the anti-aliasing filter has to have a sharp transition band between the passband and the stopband, the order of the filter is very high. However, as the order of the filter increases, the complexity and area of the filter increase, and more power is consumed. Therefore, in this paper, we propose two types of decimation filters, focusing on reducing the area of the hardware. In both cases, the complexity of the circuit is reduced by applying the required down-sampling rate in two times instead of at once. In addition, CIC decimation filters without a multiplier are used as the decimation filter of the first stage. The second stage is implemented using a CIC filter and a down sampler with an anti-aliasing filter, respectively. It is designed with Verilog-HDL and its function and implementation are validated using ModelSim and Quartus, respectively.