• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.1
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• pp.20-39
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• 2020

This paper considers a downlink multi-carrier cooperative non-orthogonal multiple access (NOMA) transmission, where no direct link exists between the far user and the base station (BS), and the communication between them only relies on the assist of the near user. Firstly, the BS sends a superimposed signal of the far and the near user to the near user, and then the near user adopts simultaneous wireless information and power transfer (SWIPT) to split the received superimposed signal into two portions for energy harvesting and information decoding respectively. Afterwards, the near user forwards the signal of the far user by utilizing the harvested energy. A minimum data is required to ensure the quality of service (QoS) of the far user. We jointly optimize power allocation, subcarrier allocation, time allocation, the power allocation (PA) coefficient and the power splitting (PS) ratio to maximize the number of data bits received at the near user under the energy causality constraint, the minimum data constraint and the transmission power constraint. The block-coordinate descent method and the Lagrange duality method are used to obtain a suboptimal solution of this optimization problem. In the final simulation results, the superiority of the proposed NOMA scheme is confirmed compared with the benchmark NOMA schemes and the orthogonal multiple access (OMA) scheme.

• Journal of the Korea Society of Computer and Information
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• v.9 no.2
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• pp.7-17
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• 2004

It requires that user have to verify and conform with user authentication Protocol on non-meet face to face internet services offered by mobile terminal which user make known user's own intention, and user be using the normal. It is more operation time authentication protocol than Access control Protocol. That is what need to be user authentication protocol have verified security. non-reputation, and improved high-performance in operation time for mobile terminal. In order to solve the above demand, in this paper, we would design for mobile terminal of TCP User Authentication ECC Algorithm Protocol with a performance test. Algorithm has 160 bit key and designed IPv4 & IPv6 frame architecture. We should conclude that the proposed protocol have more verified security, non-reputation, confidentiality, and improved high-performance in operation time of mobile terminal from 1 to 17 times than before.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.48-54
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• 2021

In most existing researches on non-orthogonal multiple access (NOMA) with symmetric superposition coding (SSC), uniform sources have been usually considered. For the first part in this two-part paper, for the strongest channel gain user, we showed that the bit-error rate (BER) for the optimal maximum a-posteriori (MAP) receiver for the non-uniform source improves slightly, compared to that of the conventional receiver for the uniform sources. We demonstrate that in communication scenarios of the non-uniform source NOMA schemes, for the weakest channel gain user, the BER performance of the optimal MAP receiver for a non-uniform source improves greatly, compared to that of the conventional receiver for uniform sources. We first derive an analytical expression of the BER for non-uniform source NOMA with SSC. Then, simulations demonstrate that the BER of the optimal MAP receiver for the non-uniform source improves, compared with that of the conventional maximum likelihood (ML) receiver for the uniform sources. In result, the proposed optimal MAP receiver for the non-uniform source could be a promising scheme for SSC NOMA, with improved BER performances.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.2
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• pp.353-362
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• 2023

Messenger phishing, communications frauds crime, exploits remote control of smartphones and non-face-to-face financial transactions, causing property damage due to money transfers, as well as account opening and loans in the name of victims. Such financial accidents may be careless of victims, but the current messenger phishing criminal method is intelligent and can be seen as digging into loopholes in the non-face-to-face user verification process. In this paper we analyze how messenger phishing uses loopholes in user identification procedures in non-face-to-face financial transactions. Through experiments, it is suggested to improve the non-face-to-face verification process for safer financial transactions.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.2
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• pp.124-134
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• 2024

This study is based on the Expectation Confirmation Theory (ECT) and categorizes trust types in non-face-to-face boarding services into three dimensions: structural assurance, platform, and service provider. It analyzes the impact of these trust types on users' perceived usefulness, satisfaction, and continuous usage intentions. Using a structural equation model, the study found that the three dimensions of trust positively influence users' satisfaction and perception of usefulness, thereby promoting intentions for continuous use. However, perceived risk weakens the positive relationship between trust and continuous usage intentions. By exploring the moderating role of perceived risk in non-face-to-face boarding services, this study analyzes its impact on user behavior patterns, contributing to the optimization of service design and enhancement of user trust. This study promotes widespread acceptance and continuous use of the service, and is crucial for developing effective non-contact service strategies that meet the needs and expectations of Chinese travelers in the post-pandemic travel environment. The findings provide a new perspective and empirical evidence for understanding user attitudes and behaviors towards non-face-to-face services, holding significant theoretical and practical implications.

• Journal of the Korean Society for Library and Information Science
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• v.41 no.1
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• pp.215-230
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• 2007

The study aims at understanding that the precedent information search Patterns of on-line database users compared to non-users have an effect on user satisfaction. The research team analyzed S college students' library system use patterns to evaluate the efficiency of library information services and systems and therefore to diverse factors to improve user satisfaction. The research showed higher satisfaction from on-line system users than non-users. To satisfy user needs the research recommends more devices access methods to information.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.4
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• pp.260-270
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• 2013

This paper proposes a strategic portfolio model for managing performance of online games. The portfolio matrix is composed of two dimensions: financial performance and non-financial performance. Financial performance is measured by the conventional measure, average revenue per user (ARPU). In terms of non-financial performance, five non-financial key performance indicators (KPIs) that have been widely used in the online game industry are utilized: RU (Register User), VU (Visiting User), TS (Time Spent), ACU (Average Current User), MCU (Maximum Current User). Data envelopment analysis (DEA) is then employed to produce a single performance measure aggregating the five KPIs. DEA is a linear programming model for measuring the relative efficiency of decision making unit (DMUs) with multiple inputs and outputs. This study employs DEA as a tool for multiple criteria decision making (MCDM), in particular, the pure output model without inputs. Combining the two types of performance produces the online game portfolio matrix with four quadrants: Dark Horse, Stop Loss, Jack Pot, Luxury Goods. A case study of 39 online games provided by company 'N' is provided. The proposed portfolio model is expected to be fruitfully used for strategic decision making of online game companies.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.5
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• pp.101-110
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• 2009

The unconscious and non-intrusive measurements of activity signals or physiological signals represent important enabling technologies for realizing a ubiquitous healthcare environment as well as a related UI. Particularly, non-intrusive measurements should be used in activity monitoring system for long-term monitoring. This paper is based on activity estimation by measuring the activity signals of a user using a handhold device with an accelerometer. The user activity estimation system (UAES) presented in this paper makes non-intrusive measurements of activity signals to minimize inconveniencing a user and to create a more practical implementation in real life. Thus, a variety of positions in which the handhold device can be carried by a user for daily use is considered, such as in the front/hip/shirt pockets, a backpack, on the waist, and in the hand.

• Journal of Digital Convergence
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• v.19 no.8
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• pp.311-317
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• 2021

This study aims to propose an effective user experience of online class in the non-face-to-face through case analysis, focusing on school-linked education programs with art museums for elementary classes. To analysis domestic and international cases of school-liked education programs with art museum and to measure user experience, we were conducted with task test, in-depth interviews and surveys with experts. As a result, there were the pros and cons about the programs. Based on this, we propose a better method to increase the satisfaction of user experience for children. This study is significant in activating digital technology-based online education. This study expected to used as data on the user experience of a non-face-to-face online art education program in elementary schools in the future.

• Journal of Korea Game Society
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• v.9 no.2
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• pp.125-133
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• 2009

Game artificial intelligence is usually used to provide intelligent and adjusted game environment for user. Previously, it was used for Non-player character(NPC) playing a role of a company or an enemy through collecting and analyzing a user's behaviour. However, it was just mimicking the user's behavior. This paper introduces a method to change game environment by analyzing a user's game behavior. Game behavior data has been used to understand user's game preference. Also, the user's preference was used to provide more active game environment by reflecting decision of geographical features, items and distribution of NPC. For experiment of the suggested method, we utilized a real 2D action game and confirmed the game environment which changing properly according to the user's game play.