• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.2972-2991
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• 2016

WLAN is the best choice in the place where complex network is hard to set up. Intelligent terminals are more and more assembled in some areas now. However, according to IEEE 802.11n/802.11ac, the access-point (AP) can only serve one user at a single frequency channel. The spectrum efficiency urgently needs to be improved. In theory, AP with multi-antenna can serve multiple users if these users do not interfere with each other. In this paper, we propose a user clustering scheme that could achieve multi-user selection through the mutual cooperation among users. We focus on two points, one is to achieve multi-user communication with multiple antennas technique at a single frequency channel, and the other one is to use a way of distributed users' collaboration to determine the multi-user selection for user clustering. Firstly, we use the CSMA/CA protocol to select the first user, and then we set this user as a source node using users' cooperation to search other proper users. With the help of the users' broadcast cooperation, we can search and select other appropriate user (while the number of access users is limited by the number of antennas in AP) to access AP with the first user simultaneously. In the network node searching, we propose a maximum degree energy routing searching algorithm, which uses the shortest time and traverses as many users as possible. We carried out the necessary analysis and simulation to prove the feasibility of the scheme. We hope this work may provide a new idea for the solution of the multiple access problem.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.1
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• pp.139-146
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• 2014

Through numerous mobile device technology advances, various multimedia contents is moving towards mobile devices from existing personal computer (PC). These paradigm has emerged taking into account these idea, the so-called N-Screen, N-Screen is user-centric service to provide running and sharing on everywhere via advanced smart system in C-P-N-T (Content, Platform, Network, Terminal). Therefore we must provide securing of various contents, openended platform, and user-centric service for efficient N-Screen service. For These characteristic of N-Screen, this paper propose design and implementation of user location-based N-Screen service system. The proposed system realize user location through user's smart phone and offer automatic streaming service to user. And also, we provide web service-based extended N-Screen service. Thus, user can access various device, such as laptop, tablet, and mobile device.

• Journal of the Ergonomics Society of Korea
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• v.33 no.6
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• pp.453-463
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• 2014

Objective:The purpose of this study is to identify motion patterns for cellular phone and propose a method to identify motion patterns using a motion capture system. Background: In a smart device, the introduction of tangible interaction that can provide new experience to user plays an important role for improving user's emotional satisfaction. Firstly, user's motion patterns have to be identified to provide an interaction type using user's gesture or motion. Method: In this study, a method to identify motion patterns using a motion capture system and user's motion patterns for using cellular phone was studied. Twenty-two subjects participated in this study. User's motion patterns were identified through motion analysis. Results: Typical motion patterns for shaking, shaking left and right, shaking up and down, and turning for using cellular phone were identified. Velocity and acceleration for each typical motion pattern were identified, too. Conclusion: A motion capture system could be effectively used to identify user's motion patterns for using cellular phone. Application: Typical motion patterns can be used to develop a tangible user interface for handheld device such as smart phone and a method to identify motion patterns using motion analysis can be applied in motion patterns identification of smart device.

• Journal of Communications and Networks
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• v.18 no.4
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• pp.589-599
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• 2016

Most existing resource management problem models arise from the original desire of allocating resources in either a user-centric or network-centric manner. The difference between their objectives is obvious: user-centric methods attempt to optimize the utility of individual users, whereas network-centric models intend to optimize the collective utilities of the entire network. In this paper, from the above two aspects, we analyze the robust power control problem in device-to-device (D2D) communication underlaying cellular networks, where two types of channel uncertainty set (e.g., ellipsoidal and column-wise) are considered. In the user-centric method, we formulate the problem into the form of a Stackelberg game, where the energy efficiency (EE) of each user is the ingredient of utility function. In order to protect the cellular user equipment's (CUE) uplink transmission, we introduce a price based cost function into the objectives of D2D user equipment (DUE). The existence and uniqueness of the game with the influence of channel uncertainty and price are discussed. In the network-centric method, we aim to maximize the collective EE of CUEs and DUEs. We show that by the appropriate mathematical transformation, the network-centric D2D power control problem has the identical local solution to that of a special case of the user-centric problem, where price plays a key role. Numerical results show the performance of the robust power control algorithms in the user-centric and network-centric models.

• Journal of KIISE:Information Networking
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• v.32 no.3
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• pp.291-300
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• 2005

The Ubiquitous computer environment is thing which invisible computer that is not shown linked mutually through network so that user may use computer always is been pervasive. Intend computing environment that can use easily as user wants and it is the smart environment that user provides context awareness that is wanting computing environment. This Ubiquitous computing contains much specially weak side in security. Masquerade attack of that crawl that is quoted to user or server among device that is around user by that discrete various computing devices exist everywhere among them become possible. Hereupon, in this paper, proposed method that have following characteristic. Present authentication model through transfer or device. Suggest two method that realize authentication through device in case of moved to method(MD: Multi Domain) and user ownself space(SD: Single Domain) that realize authentication through device in case of moved user's direct path who device differs.

• The Transactions of the Korea Information Processing Society
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• v.2 no.6
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• pp.815-822
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• 1995

In the conventional UNIX system, the all device driver realized in the kern el. Hence, whenever we want to add a new device driver or change the existin g device driver, the modification of kernel is unavoidable. Generally, it is very difficult to modify the kernel codes.As a method of overcoming this difficulty, a TTY device driver model of user-level is presented in this paper. The basic concept of this model is providing a dynamic reconfiguration of TTY device driver by realizing a user-level server process for TTY device driver. In order to verify the proper y of this model, a prototype of TTY device driver has been realized in the SunOS and Linux environment and evaluated its performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.3
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• pp.657-662
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• 2017

Recently, according to the development of the smart home field, it provides a service to install and keep the smart home appliance in a user's residential environment pleasantly. However, the conventional system method has a problem in that it is not convenient because the user selects a device or manually operates the device. In this paper, we propose a system to set the priority of the devices selected by the user and proceed with the work. When a user selects a device, it recommends a device associated with the device. Compare and set the priority of each device. And it is a system that carries out work according to the set priority. Therefore the proposed system is expected to provide users with increased convenience and efficiency of work management.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.3
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• pp.347-358
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• 2016

The paper presents a software architecture for a wearable device to measure vital signs with the real-time user's behavior recognition. Taking vital signs with a wearable device help user measuring health state related to their behavior because a wearable device is worn in daily life. Especially, when the user is running or sleeping, oxygen saturation and heart rate are used to diagnose a respiratory problems. However, in measuring vital signs, continuosly measuring like the conventional method is not reasonable because motion artifact could decrease the accuracy of vital signs. And in order to fix the distortion, a complex algorithm is not appropriate because of the limited resources of the wearable device. In this paper, we proposed the software architecture for wearable device using a simple filter and the acceleration sensor to recognize the user's behavior and measure accurate vital signs with the behavior state.

• The Journal of Society for e-Business Studies
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• v.21 no.1
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• pp.147-163
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• 2016

Gender information of a smart device user is essential to provide personalized services, and multi-modal data obtained from the device is useful for predicting the gender of the user. However, the method for utilizing each of the multi-modal data for gender prediction differs according to the characteristics of the data. Therefore, in this study, an ensemble method for predicting the gender of a smart device user by using three classifiers that have text, application, and acceleration data as inputs, respectively, is proposed. To alleviate privacy issues that occur when text data generated in a smart device are sent outside, a classification method which scans smart device text data only on the device and classifies the gender of the user by matching text data with predefined sets of word. An application based classifier assigns gender labels to executed applications and predicts gender of the user by comparing the label ratio. Acceleration data is used with Support Vector Machine to classify user gender. The proposed method was evaluated by using the actual smart device log data collected from an Android application. The experimental results showed that the proposed method outperformed the compared methods.

• Journal of Internet Computing and Services
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• v.14 no.3
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• pp.81-90
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• 2013

Mobile device can get useful user information, because users have always this device. In this paper, we propose automatically story generation method and user topic extraction using user information in mobile environment. Proposed method is follows: (1) We collect user action information in mobile device. Then, (2) we extract topics from collected information. (3) For the results of (2), we determine episodes for one day. Then, (4) we generate sentences using sentence templates and we compose stories which have theme-based or time-based. Because proposed method is simpler than previous method, proposed method can work only in mobile device. There's no room to leak user information. And proposed method is expressed more informative than previous method, because proposed method is provided sentence-based result. Extracted user-topic, a result of our method, can use to analyze user action and user preference.