• Journal of Communications and Networks
• /
• 제13권3호
• /
• pp.232-239
• /
• 2011

This paper investigates the user selection problem of successive zero-forcing precoded multiuser multiple-input multiple-output (MU-MIMO) downlink systems, in which the base station and mobile receivers are equipped with multiple antennas. Assuming full knowledge of the channel state information at the transmitter, dirty paper coding (DPC) is an optimal precoding strategy, but practical implementation is difficult because of its excessive complexity. As a suboptimal DPC solution, successive zero-forcing DPC (SZF-DPC) was recently proposed; it employs partial interference cancellation at the transmitter with dirty paper encoding. Because of a dimensionality constraint, the base station may select a subset of users to serve in order to maximize the total throughput. The exhaustive search algorithm is optimal; however, its computational complexity is prohibitive. In this paper, we develop two low-complexity user scheduling algorithms to maximize the sum rate capacity of MU-MIMO systems with SZF-DPC. Both algorithms add one user at a time. The first algorithm selects the user with the maximum product of the maximum column norm and maximum eigenvalue. The second algorithm selects the user with the maximum product of the minimum column norm and minimum eigenvalue. Simulation results demonstrate that the second algorithm achieves a performance similar to that of a previously proposed capacity-based selection algorithm at a high signal-to-noise (SNR), and the first algorithm achieves performance very similar to that of a capacity-based algorithm at a low SNR, but both do so with much lower complexity.

• 한국조경학회지
• /
• 제16권1호
• /
• pp.1-12
• /
• 1988

^x This study was executed to measure the user's psychological carrying capacity in the National Park Campsite in the district of Temple Ku- Ryong as a model of analysis, which is made socio - psychological approach. The results are as follows ; 1. Since this Place hart a beautiful scenery and some cultural assets prosperties and lies near the metroplitan area, 67.5% of the user come from the district, such as Seoul, Inchon, Kyong - Ki Do, and the purpose of camping is to appease their stress and to promote friendly relationship one another. 2. Since most of the campers(86%) didn't recognize the injury of the natural environment, the enlightment movement and the public information for the protection of natural environment are urgent. And they thought that the good campsite is located near the stream(43.6%) or a quiet place(33.4%). 3. As the space per a man increase, the degree of their satisfactions showed the tendency to increase. The user's satisfaction were analyzed by three statistic methods, correlation, multiple regression and factor analysis. Affecting factors to the user's psychology by the varimax varimax rotated factor analysis were classified physical arts ecological satisfaction. 4. The carrying capacity of the campsite by the degree of psychological satisfaction of the user was measured. The result was that the proper space for one user campsite was 35m$^2$ 5. The 58% of the informants said that they root disturbed by the overcrowding in the campsite. But most of the users thought that it was not good to control the number of the users. And the 67.3% of the respondents answered that the best method was that we control the number of the users by order of arrival if we have to control it.

• 한국조경학회지
• /
• 제33권1호
• /
• pp.10-18
• /
• 2005

The main concept of social carrying capacity is based on the principle that 'there are limits to the number of users a given recreation site can accommodate in order to provide quality of recreation experience'. The quality of the experience is revealed as user's satisfaction and perceived crowding. In this respect, studies of social carrying capacity have been frequently conducted by measuring perceived crowding and satisfaction. The purpose of this study is to identify the variables affecting perceived crowding, and causality bet-ween satisfaction and perceived crowding. Four hundred seventy six visitors were selected at Naejangsan National park on peak day of autumn excursion through on-site survey. The collected data were applied by factor analysis for categorizing the research variables, and multiple regression for finding the causality among variables. The study results are follows. The expectation of crowding, as a normative variable for perceived crowding, are categorized by three factors; circulation, user facility, and landscape. The circulation factor is the most powerful affecting perceived crowding among three factor. The landscape factor, however, do not have statistical significance on perceived crowding. The causality between satisfaction and perceived crowding is found. Although this relation is significant in statistics, magnitude of the coefficient is very small. It might be interpreted that satisfaction cannot be predicted simply from a user's perception of crowding, but a multi-dimensional concept such as adaptation and coping behavior.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제14권3호
• /
• pp.1313-1336
• /
• 2020

Cognitive radio (CR) is regarded as an effective approach to avoid the inefficient use of spectrum. However, CRNs have more special security problems compared with the traditional wireless communication systems due to its open and dynamic characteristics. Primary user emulation attack (PUEA) is a common method which can hinder secondary users (SUs) from accessing the spectrum by transmitting signals who has the similar characteristics of the primary users' (PUs) signals, and then the SUs' quality of service (QoS) cannot be guaranteed. To handle this issue, we first design a multiple-phase energy detection scheme based on the cooperation of multiple SUs to detect the PUEA more precisely. Second, a joint SUs scheduling and power allocation scheme is proposed to maximize the weighted effective capacity of multiple SUs with a constraint of the average interference to the PU. The simulation results show that the proposed method can effectively improve the effective capacity of the secondary users compared with the traditional overlay scheme which cannot be aware of the existence of PUEA. Also the good delay QoS guarantee for the secondary users is provided.

• 한국비블리아학회지
• /
• 제35권1호
• /
• pp.193-219
• /
• 2024

이 연구는 경남지역 초등학교 도서관의 이용자교육 현황과 이에 대한 전담인력의 인식을 조사한 다음, 학교도서관 이용자교육의 개선방안을 제안하는 것을 목적으로 하였다. 경남지역 학교도서관 중 전담인력이 배치되어 있는 168개 학교도서관 중 설문조사에 응한 120개관을 연구대상으로 선정하였으며, 89개관이 응답하였다. 이용자교육의 내용과 방법, 이용자교육에 대한 사서교육의 이수 현황, 이용자교육에 대한 전담인력의 이해와 관심도, 이용자교육의 필요성과 효과에 대한 전담인력의 인식, 이용자교육의 방향에 대한 전담인력의 인식 등을 조사내용으로 포함하였다. 조사 결과를 토대로 하여 학교도서관 이용자교육을 개선하기 위한 방안으로 1) 이용자교육을 위한 사서교육 기회의 확대, 2) 학년별 내용과 수준을 다양화한 교육자료의 개발과 보급, 3) 이용자교육을 위한 정규교육 시간의 편성, 4) 이용자교육에 대한 역량 강화를 위한 지속적인 노력 등을 제안하였다.

• 한국통신학회논문지
• /
• 제39A권9호
• /
• pp.491-496
• /
• 2014

We derive an analytical expression for the bit-error rate (ber) of optimal single user detection (osud) of a binary phase-shift keying (bpsk) signal corrupted by a gaussian cochannel interferer (cci). the channel capacity is also calculated to investigate the ber performance.

• Journal of Information Technology Applications and Management
• /
• 제20권3_spc호
• /
• pp.201-217
• /
• 2013

This paper analyzes the effect of network neutrality regulation on social welfare using the two-sided market under the network congestion. This paper deals with zero price rule regulation which means the price regulation on the side of content. The results are as follows : First, under the monopoly platform, internet use price, contents price, and the number of internet user and content provider are all decreasing as the network congestion increases. Second, under the monopoly platform internet use price, contents price, and the number of internet user and content provider are all increasing as the network capacity increases. Third, the price of internet use and contents internet use which maximize social welfare are increasing and the number of internet user and content provider are decreasing as the network congestion increases. Fourth, optimal network capacity for monopoly platform provider is less than socially optimal network capacity. Fifth, if network neutrality regulation is enforced, the price of internet use is higher than monopoly platform provider and the price of contents is lower than monopoly platform provider. Also, the number of internet user is less than monopoly platform provider and the number of content provider is more than that. By the way, when network congestion increases, internet use price, the number of internet user, and the number of content provider are decreasing. Sixth, network neutrality regulation is more effective for internet user side than contents provider when network congestion is considered. This means that network neutrality regulation is not effective for contents market side when network congestion is seriously large.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
• /
• pp.49-52
• /
• 2001

A virtual antenna system is presented to increase the channel capacity of a smart antenna in cdma2000. Although a smart antenna system can increase channel capacity by forming a beam to a desired user direction, an increase of channel capacity is limited by the number of antenna elements. A virtual antenna is proposed to improve the channel capacity by increasing the degree of freedom. The results show that the proposed system has a larger channel capacity than a conventional smart antenna system for the same number of antenna elements.

• Journal of Korea Artificial Intelligence Association
• /
• 제2권1호
• /
• pp.1-6
• /
• 2024

In this paper, we develop an AI-based recommendation system that matches the specifications of smartphones from company 'S'. The system aims to simplify the complex decision-making process of consumers and guide them to choose the smartphone that best suits their daily needs. The recommendation system analyzes five specifications of smartphones (price, battery capacity, weight, camera quality, capacity) to help users make informed decisions without searching for extensive information. This approach not only saves time but also improves user satisfaction by ensuring that the selected smartphone closely matches the user's lifestyle and needs. The system utilizes unsupervised learning, i.e. clustering (K-MEANS, DBSCAN, Hierarchical Clustering), and provides personalized recommendations by evaluating them with silhouette scores, ensuring accurate and reliable grouping of similar smartphone models. By leveraging advanced data analysis techniques, the system can identify subtle patterns and preferences that might not be immediately apparent to consumers, enhancing the overall user experience. The ultimate goal of this AI recommendation system is to simplify the smartphone selection process, making it more accessible and user-friendly for all consumers. This paper discusses the data collection, preprocessing, development, implementation, and potential impact of the system using Pandas, crawling, scikit-learn, etc., and highlights the benefits of helping consumers explore the various options available and confidently choose the smartphone that best suits their daily lives.

• 한국통신학회논문지
• /
• 제25권3A호
• /
• pp.362-374
• /
• 2000

In this paper, trellis coded 16 QAM Multi-Carrior CDMA system is proposed, Using the equivalent signal-to-noise plus interference Power ratio (SNIR) of Multi-Carrier CDMA system in the reverse link, capacity and BER performance of trellis coded 16 QAM Multi-Carrier CDMA system are analyzed taking into account the number of multi-carrier, the number of multiple access user, the number of SC/MRC diversity branch, and Rician fading parameter in multiuser interference and Rician fading channel. And the capacity and the BER performance of trellis coded 16 QAM Multi-Carrier CDMA system using selection combining (SC) and maximal ratio cabining (MRC) diversity are numerically compared. Obtained results show that the capacity of proposed system depends on the number of multi-carrier. ti is found that the trellis coded 16 QAM Multi-Carrier CDMA system with SC/MRC antenna diversity scheme is efficient to combat multipath fading and to increase the maximum number of users in high speed data communication. With the results of analysis. MRC diversity technique provides the performance fro high speed data communications. Finally, we present a numerical approach to derive the capacity and the BER performance and to find the maximum number of multiple access user for Multi-Carrier system in multiuser interference and Rician fading channel.