• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.9
• /
• pp.3075-3093
• /
• 2014

In this paper, we consider an advanced wireless user, called primary-secondary user (PSU) who is capable of harvesting renewable energy and connecting to both the primary network and cognitive radio networks simultaneously. Recently, energy harvesting has received a great deal of attention from the research community and is a promising approach for maintaining long lifetime of users. On the other hand, the cognitive radio function allows the wireless user to access other primary networks in an opportunistic manner as secondary users in order to receive more throughput in the current time slot. Subsequently, in the paper we propose the channel access policy for a PSU with consideration of the energy harvesting, based on a Partially Observable Markov decision process (POMDP) in which the optimal action from the action set will be selected to maximize expected long-term throughput. The simulation results show that the proposed POMDP-based channel access scheme improves the throughput of PSU, but it requires more computations to make an action decision regarding channel access.

• International Journal of Computer Science & Network Security
• /
• v.22 no.2
• /
• pp.327-333
• /
• 2022

Internet Protocol Television (IPTV) has emerged as a personal entertainment source for home users. Streaming IPTV content over a wireless medium with good Quality of Service (QoS) can be a challenging task as IPTV content requires more bandwidth and Wireless Local Area Networks (WLANs) are susceptible to packet loss, delay and jitter. This research presents the capacity of IPTV using User Datagram Protocol (UDP) and TCP Friendly Rate Control (TFRC) over IEEE 802.11ac WLANs in good and bad network conditions. Experimental results show that in good network conditions, UDP and TFRC could accommodate a maximum of 78 and 75 Standard Definition Television (SDTV) users, respectively. In contrast, 15 and 11 High-Definition Television (HDTV) users were supported by UDP and TFRC, respectively. Performance of UDP and TFRC was identical in bad network conditions and same number of SDTV and HDTV users were supported by TFRC and UDP. With background Transmission Control Protocol (TCP) traffic, both UDP and TFRC can support nearly the same number of SDTV users. It was found that TFRC can co-exist fairly with TCP by giving more throughput to TCP unlike UDP.

• Journal of Broadcast Engineering
• /
• v.26 no.7
• /
• pp.855-861
• /
• 2021

Neural Architecture Search (NAS) is cutting-edge technology in the machine learning community. NAS Without Training (NASWOT) recently has been proposed to tackle the high demand of computational resources in NAS by leveraging some indicators to predict the performance of architectures before training. The advantage of these indicators is that they do not require any training. Thus, NASWOT reduces the searching time and computational cost significantly. However, NASWOT only considers high-performing networks which does not guarantee a fast inference speed on hardware devices. In this paper, we propose a multi objectives reward function, which considers the network's latency and the predicted performance, and incorporate it into the Reinforcement Learning approach to search for the best networks with low latency. Unlike other methods, which use FLOPs to measure the latency that does not reflect the actual latency, we obtain the network's latency from the hardware NAS bench. We conduct extensive experiments on NAS-Bench-201 using CIFAR-10, CIFAR-100, and ImageNet-16-120 datasets, and show that the proposed method is capable of generating the best network under latency constrained without training subnetworks.

• International conference on construction engineering and project management
• /
• 2020.12a
• /
• pp.505-509
• /
• 2020

Twitter is a useful medium to grasp various damage situations that have occurred in society. However, it is a laborious task to spot damage-related topics according to time in the environment where information is constantly produced. This paper proposes a methodology of constructing a knowledge structure by combining the BERT-based classifier and the community detection techniques to discover the topics underlain in the damage information. The methodology consists of two steps. In the first step, the tweets are classified into the classes that are related to human damage, infrastructure damage, and industrial activity damage by a BERT-based transfer learning approach. In the second step, networks of the words that appear in the damage-related tweets are constructed based on the co-occurrence matrix. The derived networks are partitioned by maximizing the modularity to reveal the hidden topics. Five keywords with high values of degree centrality are selected to interpret the topics. The proposed methodology is validated with the Hurricane Harvey test data.

• 한국HCI학회:학술대회논문집
• /
• 2009.02a
• /
• pp.1087-1094
• /
• 2009

As online community was revitalized, the internet became the second space for people's everyday life. People enter into a connection with other on-line members and they maintain and extend their relationships. Such relationships can be analyzed and visualized with social network analysis. The method oftentimes envisions the structural elements of complex social life. The study aims at visualizing the relationships among the Cyworld users and designs an application "Blow Blow Your Pinwheel", the main purpose of this application is visualizing social relationships between ego and '1chons' which is a concept of friendship in Cyworld. Designing such an application, the study focuses on closeness of relationships which we think is composed of 1)proximity 2)similarity, 3)familiarity, and 4)reciprocity. The study used these concepts in measuring the strength of relationship between ego and other 1chons(friends). Specifically, we devised survey questionnaires which asked users to evaluate the importance of the above factors of closeness, and implemented the result in calculating the strength of the relationship between ego and other by giving weights for each factor. These measurements then were applied in visualizing the relationships in the application, we designed. Through the application, we can compare on-line relationships with off-line relationships and attempt for the new approach of Social Networks.

• Korean Journal of Family Social Work
• /
• no.55
• /
• pp.265-297
• /
• 2017

This study aims to provide basic information about the policy and system improvements relevant to single elderly men, through an investigation concerning the use and needs of activity spaces near their housing environments. Eighteen single elderly men over 60-years-old living in Gunsan city of Jeonbuk province in Korea participated in in-depth interview, and the data were qualitatively analyzed. The results of the study are as follows: The social networks of the participants were focused on friends or colleagues, while mutual exchanges with their children were intermittently undertaken. Natural networks of the elderly were formed mainly in third places, such as parks, restaurants, or community facilities, and about a half of the elderly participants had no spatial needs, and the rest required spaces for meal services, the elderly living community, jobs, leisure/hobby activities, or facility improvements. The elements influencing use of activity spaces were access from the residence, health, social networks, and economic conditions. The results suggest the following: Exercise or leisure facilities supporting elderly mobility should be set up close to their residential environments. Senior facilities centered on systematic supports and shuttle buses circulating around the places that the elderly visit frequently should be considered. On the other hand, regular maintenance and education on residents' proper use of the facilities, and sufficient information and fee discounts for the general programs are needed so that the elderly could interact with the younger generation. From a public perspective, a rational system and policy based on understanding single elderly men's needs should be prepared for provision and management of the activity space.

• Journal of Agricultural Extension & Community Development
• /
• v.11 no.2
• /
• pp.225-240
• /
• 2004

This study sought to search for the new alternatives and direction to develop and strengthening rural youth education in Korea. The study was conducted through literature review on articles, proceedings and other sources relevant to the pending issues and difficulties of rural youth education in Korea. Some of the critical needs for improving rural youth education in Korea included the following aspects or alternatives; 1) Strengthening the partnership between rural adult and youth would be necessary to gain broader support and to establish the increased awareness of adults for rural youth education. 2) Better coordination and cooperative efforts should be emphasized among various programs and institutions in implementing rural youth education policies and programs. 3) Developing a strong link between the agribusiness sector and the rural youth education system should be strengthened to produce the effective results. Further activities to develop and implement diverse programs and projects to cope with new trends In farming and agriculture as well as changing trends in marketing sector of agribusiness and rural communities in Korea. The rural leadership and community networks should be established for improving the effectiveness of rural youth educational activities.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.15 no.5
• /
• pp.1-17
• /
• 2012

This study sought to discover new directions for management and operation national urban parks in Korea by analyzing the reality of the national government parks of Japan where these parks are already well established and managed. In the case of a Japanese national government park, its supporting system was established after the park was built. The means of management also shifted their direction from putting more priority to the administrative body to the residents. The management practices are changing process of its character with focus on residents as the main entity of activity from their existing position of participants. In other words, the national government parks of Japan are going beyond the previous practice of providing maintenance activities to providing experience, interpretation functions to these activities. Especially, they were establishing local networks to plan and execute programs in collaboration with the park management and NPOs. However, they fall short of tangible outcomes despite their continuous efforts to expand the community involvement and reduce the cost in maintenance. To facilitate the effective management of the urban parks in Korea in the near future, much thought needs to go into the management practices ensuring conservation of resources in the land of Korea, as well as people's use of recreation, community revitalization, and development and transfer of advanced technology to provide appropriate preparations to create urban parks in Korea.

• Research in Community and Public Health Nursing
• /
• v.21 no.4
• /
• pp.448-457
• /
• 2010

Purpose: This study attempted to identify differences in elders' health status, quality of life, and satisfaction with customized home visiting health service depending on connection to volunteerism. Methods: A total of 400 subjects participated in this research. Data were collected from May to August of 2009 and the measurement tool used for this study was the house visiting health service recording sheet recommended by the Ministry of Health. Results: According to the results of this research on elders' health status in customized home visiting health service depending on connection to volunteerism, elders' connected to volunteerism positively showed a high level in functional health status areas such as daily life performance ability, instrumental daily life performance ability and Joint exercise capacity, and in the quality of life area. Conclusion: The results of this study can be utilized as complementary information when resources and networks are used for the effective management of house visiting health service subjects.

• The Journal of Korean Society for School & Community Health Education
• /
• v.17 no.1
• /
• pp.35-47
• /
• 2016

Objectives: The purpose of this study was to examine the mediating effect of self-esteem or social support on job-related stress and depression among emergency medical technicians (EMTs). Methods: Data were collected from EMTs at emergency medical institutions and fire stations (n=257). The data were analyzed using descriptive statistics, t-test, Pearson correlation coefficient, and stepwise multiple regression with SPSS WIN 21.0. Results: Self-esteem and social support of EMTs were found to be at moderate levels (Self-esteem: M=3.04, SD=0.43; Social support: M=3.65, SD=0.43) Job-related stress was positively correlated with depression: the higher the job-related stress score, the higher the depression score. Moreover, self-esteem score or social support score was negatively associated with job-related stress and depression: the higher the self-esteem score or the higher the social support score, the lower the job related stress score and the depression score. Conclusions: Future research should address how social support and networks interact and together affect self-esteem for job-related stress and depression.