• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1128-1135
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• 2010

The relay based cellular system has been introduced to provide the service to satisfy the user requirement. The main reasons of using relay station are to expand a service coverage and to increase a system throughput with satisfying the service requirement level. This paper proposes a new resource allocation algorithm which supports the users' throughput fairness and service coverage in the Fixed Relay Based Cellular system with OFDMA. The performance of proposed algorithm is compared with the performances of proportional fairness(PF) algorithm. The simulation result shows that the proposed algorithm increases the number of active users in the service coverage while paying small amount of throughput loss.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.6 s.336
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• pp.41-52
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• 2005

In wireless networks there are various errors, caused by multi-path fading and interference between devices which lower the network Performance. Especially, performance of IEEE 802.IS.3 High-Rate WPAN (Wireless Personal Area Network) which is operated in ISM unlicensed frequency band is easily affected by channel errors. In this paper, we propose a scheduling algorithm which takes channel errors into consideration in scheduling asynchronous data traffic. The proposed scheduling algorithm can allocate CTA(Channel Time Allocation) proportionally in accordance with the requested channel time of each device. It also prevents waste of channel time by allocating CTA of the channel-error devices to other channel-error free devices. After recovering from the channel error, the devices are compensated as much as they conceded during channel error status. Simulation results show that the proposed scheduling algorithm is superior to the existing SRPT(Shortest Remain Processing Time) and RR(Round Robin) in throughput and fairness aspects.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.6
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• pp.2160-2179
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• 2015

In many Radio Frequency Identification (RFID) applications, the reader recognizes the tags within its scope repeatedly. For these applications, some algorithms such as the adaptive query splitting algorithm (AQS) and the novel semi-blocking AQS (SBA) were proposed. In these algorithms, a staying tag retransmits its ID to the reader to be identified, even though the ID of the tag is stored in the reader's memory. When the length of tag ID is long, the reader consumes a long time to identify the staying tags. To overcome this deficiency, we propose a slot allocated blocking anti-collision algorithm (SABA). In SABA, the reader assigns a unique slot to each tag in its range by using a slot allocation mechanism. Based on the allocated slot, each staying tag only replies a short data to the reader in the identification process. As a result, the amount of data transmitted by the staying tags is reduced greatly and the identification rate of the reader is improved effectively. The identification rate and the data amount transmitted by tags of SABA are analyzed theoretically and verified by various simulations. The simulation and analysis results show that the performance of SABA is superior to the existing algorithms significantly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10B
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• pp.866-879
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• 2004

This paper presents a pricing model for maximizing a service provider's profit, taking into account consumers' quality-of-service dependent willingness to pay, in integrated voice/data mobile services. For the voice and the data services, time-sensitive pricing and volume-sensitive pricing mechanism will be applied, respectively, as in the case of Korea's mobile service market. Assuming that consumers are very sensitive to call interruption during handoff moments, the model presented here considers reserving guard channels exclusively for handoff traffic, in the process of frequency channels allocation, as well as guaranteeing consumers quality of service regarding call interruption rate. Ultimately, this model proposes a means to guarantee the quality of service in the short term, through pricing strategies as well as channel allocation policies, and the simulation results show that without expanding system resources, there exists a trade-off between profit and quality-of-service guarantee.

• Journal of Internet Computing and Services
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• v.19 no.4
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• pp.27-33
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• 2018

In the process of submitting a manuscript to a journal in order to present the results of the research at the research institution, researchers often proofread the manuscript because it can manuscripts to communicate the results more effectively. Currently, most of the manuscript proofreading companies use the manual proofreader assignment method according to the subjective judgment of the matching manager. Therefore, in this paper, we propose a topic-based proofreader matching method for effective proofreading results. The proposed method is categorized into two steps. First, a topic modeling is performed by using Latent Dirichlet Allocation. In this process, the frequency of each document constituting the representative document of a user is determined according to the importance of the document. Second, the user similarity is calculated based on the cosine similarity method. In addition, we confirmed through experiments by using real-world dataset. The performance of the proposed method is superior to the comparative method, and the validity of the matching results was verified using qualitative evaluation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.69-74
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• 2009

A novel protocol is proposed to achieve sub-carner-based rate adaptation in OFDM-based wireless systems. The protocol requires the addition of one OFDM symbol to the Clear-to-Send (CTS) packet defined in the IEEE 802.11 standard_ When receiving a Ready-To-Send (RTS) packet, the receiver determines the number of bits to be allocated in each sub-carrier through channel estimation. This decision is delivered to the sender using an additional OFDM symbol. That is, bit-allocation over sub-carriers is achieved using only one additional OFDM symbol. The protocol also provides an error recovery process to synchronize the bit-allocation information between the sender and receiver. The protocol enhances the channel efficiency in spite of the overhead of one additional OFDM symbol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5A
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• pp.325-338
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• 2012

In this paper, a radio resource allocation scheme for a multi-hop relay transmission in cognitive radio (CR) system is proposed to support the employment of relay nodes in IEEE 802.22 standard for wireless regional area network (WRAN). An optimization problem is formulated to maximize the number of serving secondary users (SUs) under system constraints such as time-divided frame structure for multiplexing and a single resource-unit to every relay-hop. However, due to mathematical complexity, the optimization problem is solved with a sub-optimal manner instead, which takes three steps in the order of user selection, relay/path selection, and frequency selection. In the numerical analysis, this proposed solution is evaluated in terms of service rate denoting as the ratio of the number of serving SUs to the number of service-requesting SUs. Simulation results show the condition of adopting multi-hop relay and the optimum number of relaying hops by comparing with the performance of 1-hop system.

• Journal of the Korea Society for Simulation
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• v.28 no.1
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• pp.1-9
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• 2019

Recently, as the importance of warehouses has increased, much efforts are being made to improve the picking process in order to cope with a small amount of high frequency and fast delivery. This study proposes an algorithm to assign orders to pickers in the situation where Single Order Picking policy is used. This algorithm utilizes five attributes related to picking such as picking processing time, elapsed time after receipt of order, inspection/packing workstation situation, picker error, customer importance. A measure of urgency is introduced so that the units of measure for each attribute are the same. The higher the urgency, the higher the allocation priority. In the proposed algorithm, the allocation policy can be flexibly adjusted according to the operational goal of the picking system by changing the weight of each attribute. Simulation experiments were performed on a hypothetical small logistics warehouse. The results showed excellent performance in terms of system throughput and flow time.

• Journal of Information Science Theory and Practice
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• v.10 no.3
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• pp.40-56
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• 2022

This paper aims to implement a topic modeling technique for extracting the topics of online discussions among library professionals in India. Topic modeling is the established text mining technique popularly used for modeling text data from Twitter, Facebook, Yelp, and other social media platforms. The present study modeled the online discussions of Library and Information Science (LIS) professionals posted on Lis Links. The text data of these posts was extracted using a program written in R using the package "rvest." The data was pre-processed to remove blank posts, posts having text in non-English fonts, punctuation, URLs, emails, etc. Topic modeling with the Latent Dirichlet Allocation algorithm was applied to the pre-processed corpus to identify each topic associated with the posts. The frequency analysis of the occurrence of words in the text corpus was calculated. The results found that the most frequent words included: library, information, university, librarian, book, professional, science, research, paper, question, answer, and management. This shows that the LIS professionals actively discussed exams, research, and library operations on the forum of Lis Links. The study categorized the online discussions on Lis Links into ten topics, i.e. "LIS Recruitment," "LIS Issues," "Other Discussion," "LIS Education," "LIS Research," "LIS Exams," "General Information related to Library," "LIS Admission," "Library and Professional Activities," and "Information Communication Technology (ICT)." It was found that the majority of the posts belonged to "LIS Exam," followed by "Other Discussions" and "General Information related to the Library."

• Journal of People, Plants, and Environment
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• v.24 no.6
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• pp.563-572
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• 2021

Background and objective: The ongoing COVID-19 pandemic restricted daily life, forcing people to spend time indoors. With the growing interest in mental health issues and residential environments, 'pet plants' have been receiving attention during the unprecedented social distancing measures. This study aims to analyze the change in trends of pet plants before and during the COVID-19 pandemic and provide basic data for studies related to pet plants and directions of future development. Methods: A total of 2,016 news articles using the keyword 'pet plants' were collected on Naver News from January 1, 2018 to August 15, 2019 (609 articles) and January 1, 2020 to August 15, 2021 (1,407 articles). The texts were tokenized into words using KoNLPy package, ultimately coming up with 63,597 words. The analyses included frequency of keywords and topic modeling based on Latent Dirichlet Allocation (LDA) to identify the inherent meanings of related words and each topic. Results: Topic modeling generated three topics in each period (before and during the COVID-19), and the results showed that pet plants in daily life have become the object of 'emotional support' and 'healing' during social distancing. In particular, pet plants, which had been distributed as a solution to prevent solitary deaths and depression among seniors living alone, are now expanded to help resolve the social isolation of the general public suffering from COVID-19. The new term 'plant butler' became a new trend, and there was a change in the trend in which people shared their hobbies and information about pet plants and communicated with others in online. Conclusion: Based on these findings, the trend data of pet plants before and after the outbreak of COVID-19 can provide the basis for activating research on pet plants and setting the direction for development of related industries considering the continuous popularity and trend of indoor gardening and green hobby.