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Performance of ZF Precoder in Downlink Massive MIMO with Non-Uniform User Distribution

  • Kong, Chuili;Zhong, Caijun;Zhang, Zhaoyang
    • Journal of Communications and Networks
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    • v.18 no.5
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    • pp.688-698
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    • 2016
  • In this paper, we investigate the achievable sum rate and energy efficiency of downlink massive multiple-input multiple-output antenna systems with zero-forcing precoding, by taking into account the randomness of user locations. Specifically, we propose two types of non-uniform user distributions, namely, center-intensive user distribution and edge-intensive user distribution. Based on these user distributions, we derive novel tight lower and upper bounds on the average sum rate. In addition, the impact of user distributions on the optimal number of users maximizing the sum rate is characterized. Moreover, by adopting a realistic power consumption model which accounts for the transmit power, circuit power and signal processing power, the energy efficiency of the system is studied. In particular, closed-form solutions for the key system parameters, such as the number of antennas and the optimal transmit signal-to-noise ratio maximizing the energy efficiency, are obtained. The findings of the paper suggest that user distribution has a significant impact on the system performance: for instance, the highest average sum rate is achieved with the center-intensive user distribution, while the lowest average sum rate is obtained with the edge-intensive user distribution. Also, more users can be served with the center-intensive user distribution.

User Interface Styles for Different Office Tasks (사무업무 형태에 따른 적정 컴퓨터 사용자 인터페이스)

  • 최필성;곽지영;한성호
    • Proceedings of the ESK Conference
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    • 1994.04a
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    • pp.7-18
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    • 1994
  • Many office tasks have been automated by using computers to increase task productivity. The productivity of performing office tasks is dependent not only upon automating the task procedures, but also upon the usability of user interfaces. However, the literature lacks human factors research on evaluating the usability of user interface styles when they are used for performing different office tasks. This study evalu- ated the usability of user interfaces styles when performing various office tasks. User interface styles considered include menu-selection, command language, form fill-in, iconic styles, etc. A task analysis was conducted toclassify representative office tasks. A variety of analysis techniques such as brainstorming, analytic hierarchy process, prototyping, and expert opinions were used to evaluate the usability of the interfaces. The analysis procedures and results are described along with guidelines for selecting user interfaces in terms of subjective preferences and performance measures.

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A Study on Emotional Information System Using User Color Information

  • Ko, Hye-Kyeong
    • International journal of advanced smart convergence
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    • v.8 no.4
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    • pp.82-92
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    • 2019
  • The appropriate use of color and light can increase psychological stress or feelings of mental stability. As such, many people currently use color therapy, which provides relaxation and stability through color stimulation. Many people currently use color therapy, which provides relaxation and stability through color stimulation. The smartphone-based psychological color therapy system that is to be developed through the study is a method for relieving stress. This study examines a method of using smartphones to understand user's emotional information such as types of stress and to provide color therapy information regarding these emotions. The goal of this study is to use the user's smart phone to provide color therapy that employs the user's emotional information. The intelligent emotion system, which uses platforms such as mobile devices and the PC, was designed considering the user's context, and it provides the user with various data formats such as images, video, text, audio, to send results to the user. The system was developed in the form of a service-based mobile application. The study designed an emotional color therapy system that uses a smartphone to measure the user's stress and provides appropriate color therapy.

A Model-based Collaborative Filtering Through Regularized Discriminant Analysis Using Market Basket Data

  • Lee, Jong-Seok;Jun, Chi-Hyuck;Lee, Jae-Wook;Kim, Soo-Young
    • Management Science and Financial Engineering
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    • v.12 no.2
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    • pp.71-85
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    • 2006
  • Collaborative filtering, among other recommender systems, has been known as the most successful recommendation technique. However, it requires the user-item rating data, which may not be easily available. As an alternative, some collaborative filtering algorithms have been developed recently by utilizing the market basket data in the form of the binary user-item matrix. Viewing the recommendation scheme as a two-class classification problem, we proposed a new collaborative filtering scheme using a regularized discriminant analysis applied to the binary user-item data. The proposed discriminant model was built in terms of the major principal components and was used for predicting the probability of purchasing a particular item by an active user. The proposed scheme was illustrated with two modified real data sets and its performance was compared with the existing user-based approach in terms of the recommendation precision.

Security Analysis of a Biometric-Based User Authentication Scheme (Biometric 정보를 기반으로 하는 사용자 인증 스킴의 안전성 분석)

  • Lee, Young Sook
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.10 no.1
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    • pp.81-87
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    • 2014
  • Password-based authentication using smart card provides two factor authentications, namely a successful login requires the client to have a valid smart card and a correct password. While it provides stronger security guarantees than only password authentication, it could also fail if both authentication factors are compromised ((1) the user's smart card was stolen and (2) the user's password was exposed). In this case, there is no way to prevent the adversary from impersonating the user. Now, the new technology of biometrics is becoming a popular method for designing a more secure authentication scheme. In terms of physiological and behavior human characteristics, biometric information is used as a form of authentication factor. Biometric information, such as fingerprints, faces, voice, irises, hand geometry, and palmprints can be used to verify their identities. In this article, we review the biometric-based authentication scheme by Cheng et al. and provide a security analysis on the scheme. Our analysis shows that Cheng et al.'s scheme does not guarantee any kind of authentication, either server-to-user authentication or user-to-server authentication. The contribution of the current work is to demonstrate these by mounting two attacks, a server impersonation attack and a user impersonation attack, on Cheng et al.'s scheme. In addition, we propose the enhanced authentication scheme that eliminates the security vulnerabilities of Cheng et al.'s scheme.

A Study on the Approach Method of Product Form by User Mental -Concentrated on Implicit & Explicit memory- (사용자 심리적 연상에 의한 제품형태 접근 방법에 관한연구 -암묵기억과 외현기억을 중심으로-)

  • 안철홍;정도성
    • Archives of design research
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    • v.15 no.1
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    • pp.27-36
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    • 2002
  • To do this, study of human memory and theoretical approach on form in general is carried out to compare the types of memories and the stage of perceive theoretically to discover the relationship between psychological perceive and form. In the second please, scenario of form recognition in cultural aspect is studied through various written records to obtain unbiased critics on what a person can feel from a form through various analysis and experiment. Examples will be given on products designed on the basis of correlation with form through analysis. Through this procedure, elements of reactions on implicit and explicit is derived (Data obtained from experiments on computers and inquiries are used) Analyzed elements are than divided into, general knowledge, memories of reality and subconsciousness memories and basic mental image and user mental image and mental image of form of each products are analyzed. In the third phase, the way of adapting of the elements obtained from the analysis of implicit and explicit reaction to the field of design is predicted. Together with this, future theme this the study will be suggested. Confusions obtained from this study can be listed as below.

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Two-Way Relaying-Based Two-Hop Two-User Multiple-Input Multiple-Output System

  • Cho, Young Seek;Choi, Seyeong
    • Journal of information and communication convergence engineering
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    • v.12 no.2
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    • pp.67-74
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    • 2014
  • In multi-hop communication systems, two-way relaying is one of the solutions to mitigate the spectral efficiency loss caused by a half-duplex transmission. In this paper, a simple two-way relaying scheme is proposed for two-hop two-user multiple input multiple output (MIMO) systems. In the proposed system, a base station and a relay station (RS), both equipped with two antennas, form a point-to-point MIMO channel, while the RS and two single-antenna mobile users form a point-to-multipoint multiuser (MU)-MIMO channel. Numerical examples show that the proposed system achieves a significant sum rate gain as compared to a one-way relaying system as the distance between a relay and the two users decreases. We also show that although we can expand the proposed scheme to more than two users, its performance gain as compared to that of one-way relaying decreases with an increase in the number of users.

Power Allocation and Capacity Analysis of OFDM-based Unlicensed User in TV White Space (TV 화이트 스페이스에서 OFDM 기반 비인가 사용자의 파워 할당 기법 및 용량 분석)

  • Lim, Sung-Mook;Hong, Dae-Sik
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.49 no.8
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    • pp.70-76
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    • 2012
  • In this paper, we propose a power allocation scheme of the unlicensed user based on orthogonal frequency division multiplexing (OFDM) in the TV white space (TVWS). Power constraints in TVWS should be satisfied in the time domain. However, because OFDM has high PAPR (peak-to-average power ratio), it is difficult to satisfy power constraints of TVWS in the time domain. Furthermore, the conventional power allocation schemes cannot be generally applied to unlicensed user in TVWS. Therefore, we propose a power allocation scheme to satisfy power constraints of TVWS by reducing PAPR in the time domain. In addition, we analyze the capacity of the unlicensed user based on OFDM in a closed form. Based on the capacity analysis, as the number of subcarriers decreases, the capacity can be enhanced. In simulation results, we show that the capacity of the unlicensed user increases, as the number of subcarriers decreases and the mean of the channel between the transmitter and the receiver of the unlicensed user increases.

A Deep Learning Model for Predicting User Personality Using Social Media Profile Images

  • Kanchana, T.S.;Zoraida, B.S.E.
    • International Journal of Computer Science & Network Security
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    • v.22 no.11
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    • pp.265-271
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    • 2022
  • Social media is a form of communication based on the internet to share information through content and images. Their choice of profile images and type of image they post can be closely connected to their personality. The user posted images are designated as personality traits. The objective of this study is to predict five factor model personality dimensions from profile images by using deep learning and neural networks. Developed a deep learning framework-based neural network for personality prediction. The personality types of the Big Five Factor model can be quantified from user profile images. To measure the effectiveness, proposed two models using convolution Neural Networks to classify each personality of the user. Done performance analysis among two different models for efficiently predict personality traits from profile image. It was found that VGG-69 CNN models are best performing models for producing the classification accuracy of 91% to predict user personality traits.

The effects of the usability of products on user's emotions - with emphasis on suggestion of methods for measuring user's emotions expressed while using a product -

  • Jeong, Sang-Hoon
    • Archives of design research
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    • v.20 no.2 s.70
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    • pp.5-16
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    • 2007
  • The main objective of our research is analyzing user's emotional changes while using a product, to reveal the influence of usability on human emotions. In this study we have extracted some emotional words that can come up during user interaction with a product and reveal emotional changes through three methods. Finally, we extracted 88 emotional words for measuring user's emotions expressed while using products. And we categorized the 88 words to form 6 groups by using factor analysis. The 6 categories that were extracted as a result of this study were found to be user's representative emotions expressed while using products. It is expected that emotional words and user's representative emotions extracted in this study will be used as subjective evaluation data that is required to measure user's emotional changes while using a product. Also, we proposed the effective methods for measuring user's emotion expressed while using a product in the environment which is natural and accessible for the field of design, by using the emotion mouse and the Eyegaze. An examinee performs several tasks with the emotion mouse through the mobile phone simulator on the computer monitor connected to the Eyegaze. While testing, the emotion mouse senses user's EDA and PPG and transmits the data to the computer. In addition, the Eyegaze can observe the change of pupil size. And a video camera records user's facial expression while testing. After each testing, a subjective evaluation on the emotional changes expressed by the user is performed by the user him/herself using the emotional words extracted from the above study. We aim to evaluate the satisfaction level of usability of the product and compare it with the actual experiment results. Through continuous studies based on these researches, we hope to supply a basic framework for the development of interface with consideration to the user's emotions.

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