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

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.11b
• /
• pp.574-576
• /
• 2005

스마트 홈을 구현하기 위한 핸드폰을 이용한 리모트 컨트롤러나 PDA를 통한 통합 리모트 컨트롤러 등의 통합 리모트 컨트롤러에 관한 연구는 활발히 진행되어 오고 있다. 본 논문은 이러한 리모트 컨트롤러에 관한 연구에 대해 두 가지의 새로운 방향을 생각해 보았다. 첫째로 리모트 컨트롤러를 작동시키기 위해서는 핸드폰이나 PDA등의 input 디바이스가 반드시 필요했던 단점을 보완해서 임베디드 보드에 input device 기능을 포함하는 것이다. 그리고 두 번째는 임베디드 리모트 컨트롤러에 user profile을 두어서 단순한 채널 변경의 기능만을 하는 리모트 컨트롤러가 아니라 사용자의 선호도 등의 정보를 가지고 지능적으로 집안 환경을 최적화된 조건으로 만들 수 있도록 설계 했다. 즉 사용자가 가장 좋아하는 TV채널이나 실내온도 등의 정보를 가지고 각 사용자에게 최적화된 환경을 리모트 컨트롤러가 스스로 작동시킬 수 있게 되는 것이다. 그리고 가전을 작동시키기 위해서 임베디드 보드에 있는 IrDA 통신모듈을 통해 일정한 코드 값만 보내주면 되기 때문에 일반적으로 리모트 컨트롤러로 제어가 가능한 거의 모든 전자제품이 쉽게 제어 가능하다.

• The Korean Journal of Health Service Management
• /
• v.5 no.1
• /
• pp.1-13
• /
• 2011

The purpose of this paper was to evaluate performance of information system for one national university hospital in order to identify the factors influencing performance of information system. KPIs were collected for 181 users of information system (41 doctors, 104 nurses, and 11 medical supporting staffs, and 25 administrative staffs) from August 10 to 24, 2010. The results were as follows: Average performance score for input layer was 3.16; average performance score for process layer was 3.35; and average performance score for business layer was 3.57. Scores for input layer was lowest for nurses and scores for process and business layer were lowest for doctors. Results from the path analysis showed that system quality, demographic characteristics, and security significantly influenced management process but these factors except demographic characteristics influenced user satisfaction; and management process also significantly influenced user satisfaction.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.9
• /
• pp.2120-2133
• /
• 2013

In this paper, we address the problem of linear minimum mean-squared error (MMSE) transmitter design for the cognitive radio (CR) multi-user multiple-input single-output (MU-MISO) broadcasting channel (BC), where the cognitive users are subject to not only a sum power constraint, but also a interference power constraint. Evidently, this multi-constraint problem renders it difficult to solve. To overcome this difficulty, we firstly transform it into its equivalent formulation with a single constraint. Then by utilizing BC-MAC duality, the problem of BC transmitter design can be solved by focusing on a dual MAC problem, which is easier to deal with due to its convexity property. Finally we propose an efficient two-level iterative algorithm to search the optimal solution. Our simulation results are provided to corroborate the effectiveness of the proposed algorithm and show that this proposed CR MMSE-based scheme achieves a suboptimal sum-rate performance compared to the optimal DPC-based algorithm with less computational complexity.

• Proceedings of the KIEE Conference
• /
• 2003.11c
• /
• pp.349-352
• /
• 2003

A personal low-frequency stimulator is a portable device to relax muscle pains of a person. The stimulator generates combined low-frequency pulses to be applied to pads attached to painful muscles. This paper reports a development of such device with its characteristic analyses. The major components of our stimulator are MCU, high-voltage generating circuit part, high-voltage switching circuit part, input switch part and display unit. High-voltage generating circuit is designed by using a boost converter circuit and allows user control of the output voltage. High-voltage switching circuit, controlled by MCU, generates output voltage to be applied to pads. Input switch part is composed of power supply, intensity selection, mode selection and memory. Display unit adopts a text LCD module to display modes, Intensity, output frequency and user set-up time. Our designed safety circuit, to protect human body from possible electric shock, slowly increases the output voltage to the selected output intensity. It continuously checks the output pulse shape and disable the output when dangerous pulses are detected. This paper also shows some experimental results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.05a
• /
• pp.455-458
• /
• 2009

Bluetooth technology has been applied to mobile device, personal computers, peripherals, information and variety of consumer electronics. Not also the original Bluetooth technology must be especially focused in the application of mobile phone but applications such as wireless headsets and dial-up networking may be increased. However Bluetooth is so only focused to wireless headset application that the various software applications are presently ignored. In this paper, we propose the framework design to implement Bluetooth profile for kiosk servers, which can be used in Theater, train station, bank, government and public offices. Then mobile devices capable of processing user's input/output can be remotely accessed in these servers by using Bluetooth module and AP, although Kiosk servers are only processed user input data.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.2
• /
• pp.635-656
• /
• 2019

In this paper, we investigate the degrees of freedom (DoF) of a multi-cell multi-user multiple-input multiple-output (MIMO) interference broadcast channel (IBC) with non-cooperation distributed base stations (BS), where each BS serves users of its corresponding cell. When all BSs simultaneously transmit their own signals over the same frequency band in the MIMO IBC, the edge users in each cell will suffer the inter-cell interference (ICI) and inter-user interference (IUI) signals. In order to eliminate the ICI and IUI signals, a distributed space time interference alignment (DSTIA) approach is proposed where each BS has only limited access to distributed moderately-delay channel state information at the transmitter (CSIT). It is shown that the DSTIA scheme can obtain the appreciate DoF gains. In addition, the DoF upper bound is asymptotically achievable as the number of antenna at each BS increases. It is shown that the DSTIA method can get DoF gains over other interference alignment schemes with delayed CSIT in literature. Moreover, the DSTIA method can attain higher DoFs than the IA schemes with global CSIT for certain antenna configurations.

• Journal of Korea Multimedia Society
• /
• v.24 no.8
• /
• pp.1076-1089
• /
• 2021

Among the currently used knowledge-based authentication methods for smartphones, text and graphic-based authentication methods, such as PIN and pattern methods, use a display unit and a touch function of the display unit for input/output of secret information. Recently released smartphone form factors are trying to transform into various forms, away from the conventional bar and slate types because of the material change of the display unit used in the existing smartphone and the increased flexibility of the display unit. However, as mentioned in the study of D. Choi [1], the structural change of the display unit may directly or indirectly affect the authentication method using the display unit as the main input/output device for confidential information, resulting in unexpected security vulnerabilities. In this paper, we analyze the security vulnerabilities of the current mobile user authentication methods that is applied atypical form factor. According to the analysis results, it seems that the existing display-dependent mobile user authentication methods do not consider emerging security threats at all. Furthermore, it is easily affected by changes in the form factor of smartphones. Finally, we propose countermeasures for security vulnerabilities expected when applying conventional authentication methods to atypical form factor-based smartphones.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.17 no.3
• /
• pp.794-815
• /
• 2023

The rapid development of mobile communication not only has made the industry gradually diversified, but also has enhanced the service quality requirements of users. In this regard, it is imperative to consider jointly network slicing and mobile edge computing. The former mainly ensures the requirements of varied vertical services preferably, and the latter solves the conflict between the user's own energy and harsh latency. At present, the integration of the two faces many challenges and need to carry out at different levels. The main target of the paper is to minimize the energy consumption of the system, and introduce a multi-slice joint task offloading and resource allocation scheme for massive multiple input multiple output enabled heterogeneous networks. The problem is formulated by collaborative optimizing offloading ratios, user association, transmission power and resource slicing, while being limited by the dissimilar latency and rate of multi-slice. To solve it, assign the optimal problem to two sub-problems of offloading decision and resource allocation, then solve them separately by exploiting the alternative optimization technique and Karush-Kuhn-Tucker conditions. Finally, a novel slices task offloading and resource allocation algorithm is proposed to get the offloading and resource allocation strategies. Numerous simulation results manifest that the proposed scheme has certain feasibility and effectiveness, and its performance is better than the other baseline scheme.

• International journal of advanced smart convergence
• /
• v.12 no.2
• /
• pp.56-66
• /
• 2023

The goal of deep learning is to extract complex features from multidimensional data use the features to create models that connect input and output. Deep learning is a process of learning nonlinear features and functions from complex data, and the user data that is employed to train deep learning models has become the focus of privacy concerns. Companies that collect user's sensitive personal information, such as users' images and voices, own this data for indefinite period of times. Users cannot delete their personal information, and they cannot limit the purposes for which the data is used. The study has designed a deep learning method that employs privacy protection technology that uses distributed collaborative learning so that multiple participants can use neural network models collaboratively without sharing the input datasets. To prevent direct leaks of personal information, participants are not shown the training datasets during the model training process, unlike traditional deep learning so that the personal information in the data can be protected. The study used a method that can selectively share subsets via an optimization algorithm that is based on modified distributed stochastic gradient descent, and the result showed that it was possible to learn with improved learning accuracy while protecting personal information.