• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.75-82
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• 2018

In this paper, we consider a precoder design for downlink multiuser multiple-input multiple-output (MU-MIMO) in distributed antenna systems (DAS). In DAS, remote radio heads (RRHs) are placed at geographically different locations within a cell area. Three different precoder design schemes are proposed to maximize the separate or joint signal-to-leakage-plus-noise ratio (SLNR) metrics by considering RRH sum power or per-RRH power constraints. The analytical closed-form form solution for each optimization problem is presented. Through computer simulation, we show that the joint SLNR based precoding schemes have better signal-to-interference-plus-noise ratio (SINR) and bit error rate (BER) performances than the separate SLNR based schemes. Also, it is shown that the precoding scheme with RRH sum power constraint has better performance than the precoding scheme with per-RRH power constraint.

• Convergence Security Journal
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• v.19 no.1
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• pp.97-101
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• 2019

If the operating system's core file contains an Intel PT, the debugger can not only check the program state at the time of the crash, but can also reconfigure the control flow that caused the crash. We can also extend the execution trace scope to the entire system to debug kernel panics and other system hangs. The second-generation PT, the WinIPT library, includes an Intel PT driver with additional code to run process and core-specific traces through the IOCTL and registry mechanisms provided by Windows 10 (RS5). In other words, the PT trace information, which was limited access only by the first generation PT, can be executed by process and core by the IOCTL and registry mechanism provided by the operating system in the second generation PT. In this paper, we compare and describe methods for collecting, storing, decoding and detecting malicious codes of data packets in a window environment using 1/2 generation PT.

• Journal of Convergence for Information Technology
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• v.9 no.5
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• pp.34-39
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• 2019

One of the words frequently mentioned in our society today is the smart machine. Smart machines are machines that contain smart or intelligent functions. These smart machines have recently been applied in our home environment. These are phenomena that occur as a result of smart home. In a smart home environment, smart speakers have moved away from traditional music playback functions and are now increasingly serving as interfaces to control devices, the various components of a smart home. In this study, the technology trends of domestic and foreign smart speaker market are examined, problems of current products are analyzed, and necessary core technologies are described. In the domestic smart speaker market, SKT and KT are leading the related industries, while major IT companies such as Amazon, Google and Apple are focusing on launching related products and technology development.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.9 no.1
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• pp.179-187
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• 2019

With the recent development of small computing devices, IoT sensor network can be widely deployed and is now readily available with sensing, calculation and communi-cation functions at low cost. Sensor data management is a major component of the Internet of Things environment. The huge volume of data produced and transmitted from sensing devices can provide a lot of useful information but is often considered the next big data for businesses. New column-wise compression technology is mounted to the large data server because of its superior space efficiency. Since sensor nodes have narrow bandwidth and fault-prone wireless channels, sensor-based storage systems are subject to incomplete data services. In this study, we will bring forth a short overview through providing an analysis on IoT sensor networks, and will propose a new storage management scheme for IoT data. Our management scheme is based on RAID storage model using column-wise segmentation and compression to improve space efficiency without sacrificing I/O performance. We conclude that proposed storage control scheme outperforms the previous RAID control by computer performance simulation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.115-121
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• 2019

In this paper, we propose MSAG-SCS-MMA-I adaptive blind equalization with double step size with very small residual ISI and MSE at steady-state while significantly improving the convergence speed of the traditional SCS-MMA-I algorithm in 256-QAM system. And we evaluate the equalization performance for this algorithm. Different step sizes according to the absolute value of decision-directed error instead of a fixed step-size are applied to the tap update equation of MSAG-SCS-MMA-I, which is controlled by binary flags of '1' or '0' obtained from SCS-MMA-I and decision-directed algorithms. This makes for excellent equalization performance. As a result of computer simulation, we confirmed that the proposed algorithm has more better performance than the MMA, SCS-MMA-I, and MSAG-SCS-MMA-I algorithms in terms of the performance index such as residual ISI, MSE, and MD.

• Convergence Security Journal
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• v.18 no.5_1
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• pp.19-24
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• 2018

For a long time now, general-purpose processors have provided dedicated hardware / software tracing modules to provide developers with tools to fix bugs. A hardware tracer generates its enormous data into a log that is used for both performance analysis and debugging. Processor Trace (PT) is a new hardware-based tracing feature for Intel CPUs that traces branches executing on the CPU, which allows the reconstruction of the control flow of all executed code with minimal labor. Hardware tracer has been integrated into the operating system, which allows tight integration with its profiling and debugging mechanisms. However, in the Windows environment, existing studies related to PT focused on decoding only one flow in sequence. In this paper, we propose an extended PT decoder structure that provides basic data for real-time trace and malicious code detection using the functions provided by PT in Windows environment.

• Journal of Engineering Education Research
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• v.24 no.1
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• pp.24-33
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• 2021

As online learning continues to be extended, many engineering colleges are engaged in online learning activities. One of the core competencies required of engineering students in a knowledge-convergence society is communication skills. Online discussion activities are frequently used in educational field to improve communication skills. Efforts are being made to provide visual dashboards in online discussion activity systems to more effectively support online discussion activities. However there is less qualitative studies on students' experience in discussion activities. The purpose of this study is to explore the experience of engineering students participating in discussion activities using online discussion systems and visual dashboards. We interviewed 15 students who participated in online discussion activities to achieve their research objectives about their experience in utilizing the online discussion system, their perception of visual dashboards, and their experience in discussion activities. As a result of the study, students' perception of the use of the online discussion activity system, the visual dashboard, and the perception of a sense of social presence were understood. To be more effective in providing tool support, such as discussion activity systems and visual dashboards in online discussion activities, instructors need to understand the nature of learners' online discussion activities.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.12
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• pp.1520-1527
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• 2019

Superpixel methods are widely used in the preprocessing stage as a method to reduce computational complexity by simplifying images while maintaining the characteristics of images in the field of computer vision. It is common to generate superpixels with a regular size and form based on the pixel values rather than considering the characteristics of the image. In this paper, we propose a method to generate superpixels considering the characteristics of an image according to the application. The proposed method consists of two steps, and the first step is to oversegment an image so that the boundary information of the image is well preserved. In the second step, superpixels are merged based on similarity to produce the desired number of superpixels, where the form of superpixels are controlled by limiting the maximum size of superpixels. Experimental results show that the proposed method preserves the boundaries of an image more accurately than the existing method.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.9 no.4
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• pp.85-97
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• 1999

A blind signature scheme is a protocol allowing verifier to obtain a valid signature for a message m from a signer without him seeing the message. This means that the bank in collaboration with the shop cannot trace the electronic cash to user. However anonymous electronic cash also facilitates fraud and criminal acts such as money laundering anonymous blackmailing and illegal purchaes. Therefore in this paper we propose fair blind signature scheme based on KCDSA which is a domestic digital signature scheme and it apply a electronic cash system. In particularly a proposed electronic cash system have an anonymity control ability which trace a user who make use a electronic cash illegally in association with a trusted center.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.2
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• pp.55-70
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• 2006

In this paper, we propose a new access control security architecture for supporting flexibility in Secure Operating Systems. By adding virtual access control system layer to the proposed security architecture, various access control models such as MAC, DAC, and RBAC can be applied to Secure Operating Systems easily. The proposed security architecture is designed to overcome the problem of Linux system's base access control system. A policy manager can compose various security models flexibly and apply them to Operating Systems dynamically. Also, the proposed architecture is composed of 3 modules such as access control enforcement, access control decision, and security control. And access control models are abstracted to hierarchy structure by virtual access control system. And, we present the notation of policy conflict and its resolution method by applying various access control model.