• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1733-1751
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• 2015

The IEEE 802.15.4 standard not only provides a maximum of seven guaranteed time slots (GTSs) for allocation within a superframe to support time-critical traffic, but also achieves ultralow complexity, cost, and power in low-rate and short-distance wireless personal area networks (WPANs). Real-time wireless body area sensor networks (WBASNs), as a special purpose WPAN, can perfectly use the IEEE 802. 15. 4 standard for its wireless connection. In this paper, we propose an adaptive GTS allocation scheme for real-time WBASN data transmissions with different priorities in consideration of low latency, fairness, and bandwidth utilization. The proposed GTS allocation scheme combines a weight-based priority assignment algorithm with an innovative starvation avoidance scheme. Simulation results show that the proposed method significantly outperforms the existing GTS implementation for the traditional IEEE 802.15.4 in terms of average delay, contention free period bandwidth utilization, and fairness.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.308-308
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• 2004

• Journal of the Daesoon Academy of Sciences
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• v.47
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• pp.65-103
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• 2023

In The Canonical Scripture (典經), the core scripture of Daesoon Thought, the Former World and the Later World are divided into the Era of Mutual Contention and the Era of Mutual Beneficence. This concept of the Former World and the Later World appears in diagrams on I-Ching Studies (易學) in the text titled, The Comprehensive Mirror of Taegeukdo (太極道通鑑). In I-Ching Studies, Anterior Heaven (先天) and Posterior Heaven (後天) are the main concepts in Song Dynasty diagram books on I-Ching Studies. Among the diagrams of I-Ching Studies, Fuxi's Diagram of the Sequence of the Eight Trigrams, Fuxi's Diagram of the Positions of the Eight Trigrams, Fuxi's Diagram of the Sequence of the 64 Hexagrams, and Fuxi's Diagram of the Positions of the 64 Hexagrams correspond to the Anterior Heaven, and King Wen's Diagram of the Sequence of the Eight Trigrams and King Wen's Diagram of the Positions of the Eight Trigrams correspond to Posterior Heaven. In The Comprehensive Mirror of Taegeukdo, the diagrams of I-Ching Studies are reinterpreted according to Daesoon Thought. The Diagram of the Eight Trigrams of King Wen's Era corresponds to King Wen's Diagram of the Eight Trigrams in I-Ching Studies. This diagram was drawn according to the text in Chapter Five of the Treatise of Remarks on the Trigrams. This diagram corresponds to "the Era of the Nobility of Earth (地尊時代)" centered on the trigram kun (坤 / ☷ ground). Fuxi's Diagram of the Positions of the Eight Trigrams in I-Ching Studies corresponds to The Diagram of the Positions of the Eight Trigrams of Fuxi's Era in Daesoon Thought. The most significant feature of this diagram is that the trigrams assigned to the directions of north and south match the hexagram indicating the obstruction of Heaven and Earth. This is hexagram 12 (否), meaning "obstruction," and it depicts no exchange or communication between Yin and Yang. Naturally, this symbolizes mutual destruction overtaking Yin and Yang. Daesoon Thought expresses this as "the Era of the Nobility of Heaven (天尊時代)." The most significant feature of The Diagram of the Eight Trigrams of the Corrected Book of Changes in The Comprehensive Mirror of Taegeukdo is that the trigrams assigned to the directions of south and north are indicative of hexagram 11, Peace on Earth and in Heaven (泰). This is a diagram in which mutual destruction is resolved through the Five Phases because the trigrams for water (坎 / ☵) and fire (離 / ☲) are in a corrected orientation. Therefore, this diagram symbolizes a world "free from Mutual Contention" and "the Era of Human Nobility (人尊時代)." According to the contents of The Canonical Scripture, the Supreme God performed the Reordering Works of the Three Realms to correct the Mutual Contention of the Former World, and as a result, the Mutual Contention of the Former World will give way to the implementation of the Dao of Mutual Beneficence. The Supreme God's Reordering Works of the Three Realms have been completed in the realm of divine beings, but in the Later World, they appear as an Earthly Paradise where the Dao of Mutual Beneficence is realized. The diagram depicting the Later World is The Diagram of the Eight Trigrams of the Era of the Corrected Book of Changes in The Comprehensive Mirror of Taegeukdo.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.4
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• pp.373-382
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• 2000

The most important metric in wormhole-routed networks is the start-up latency. In this paper, we present new multicast algorithms that reduce node contention so that multiple multicast messages can be implemented with reduced latency. By exploiting available channels evenly as much as possible, these new algorithms show better performance than the existing multicast algorithms for wormhole 2D systems when multiple multicasts are involved. All algorithms presented are proven to be deadlock-free. A simulation study has been conducted that compares the performance of these multicast algorithms under various situations in a 2D mesh. We show that the overall performance of ours are up to 20% better than the previous studies. We observe that reducing the number of the generated multidestination messages closely related to shorter message latency. These proposed algorithms can be easily extended to 3D mesh systems.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.4
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• pp.57-65
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• 2010

Application of WBAN technology in medical field facilitates the prevention of diseases by collecting the vital signs remotely. It also enables to prevent the accidental emergency situation in advance plus long-tem monitoring of patients with chronic diseases such as heart diseases, hypertension, or the elderly and infirm. For emergency patients, major vital signal information collected by the 'Sensing' should have the top priority and such information should be transferred as promptly as possible without competition. In addition, when an emergency occurs to a patient, a priority mechanism is necessitated for a urgent message to get through to the final destination. However, LR-WPAN IEEE 802.15.4 technology does not consider such emergency message handling features. To deal with aforementioned issues, the IEEE 802.15.4 super frame protocol structure has been designed for stable transfer of emergency information in WBAN environment in this study, and alternation to super frame structures have been made, allowing GTS(Guaranteed Time Slot) can be used first at CFP (Contention Free Period) by reserving the resources in advance and prioritize the emergency signals. NS-2 has been utilized for the performance test and analysis.

• Journal of Communications and Networks
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• v.17 no.3
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• pp.247-255
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• 2015

In this paper, we propose an adaptive time division multiple access based medium access control (MAC) protocol, called bitmap-assisted shortest job first based MAC (BS-MAC), for hierarchical wireless sensor networks (WSNs). The main contribution of BS-MAC is that: (a) It uses small size time slots. (b) The number of those time slots is more than the number of member nodes. (c) Shortest job first (SJF) algorithm to schedule time slots. (d) Short node address (1 byte) to identify members nodes. First two contributions of BS-MAC handle adaptive traffic loads of all members in an efficient manner. The SJF algorithm reduces node's job completion time and to minimize the average packet delay of nodes. The short node address reduces the control overhead and makes the proposed scheme an energy efficient. The simulation results verify that the proposed BS-MAC transmits more data with less delay and energy consumption compared to the existing MAC protocols.

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.105-119
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• 2008

This study explored the status of free time activities among the dental technicians who are working at Seoul, Gyonggido, and Gangwondo. On the basis of this research, we aim to present needs and applicable solutions to improve the working conditions and enhance the quality of life through more effective time management in free time activities that lead to their self development and far more enriched life. 500 subjects were randomly chosen and the questionary sheets were provided. Among them, 305 sheets were returned to be analysed through SPSS Win 10.0 software and the results are as follows; First, mean in the satisfaction of leisure activities was 3.44(SD=.73). Mean in sub categories was as follows; psychological factor(M=3.65, SD=.71), social factor(M=3.54, SD=.75), rest factors(M=3.52, SD=.63), physical factor(M=3.43, SD=.88), other factors(M=3.40, SD=.66), circumstantial factor(M=3.33, SD=.63), educational factor(M=3.24, SD=.73). Second, the most relevant sub categories in the satisfaction of leisure activities were social, educational, physical, and other circumstantial factors by sequence. Factors that affect leisure activities satisfaction were career and status of health, which shows statistical significance(p<.001). That is to say, contention of this study is that the general characteristics are closely related with and affect the types and the level of satisfaction in leisure activities of the subjects. Considering these results, the dental businesses and the associations of dental technicians should recognize the needs to improve the time management through more efficient cooperations between dentists and back office dental team, systemized working time, and introduction of incentive system among others. On the basis of this appreciation, the dental business should provide more time and various opportunities with the dental technicians. Dental technicians also need to reconsider their appreciations of leisure activities, that is, leisure activities are not just spending time doing something but they refresh them and enable them to be more active and faithful to home and work.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.88-96
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• 2011

Underwater acoustic communication is applicable in various areas, such as ocean data collection, undersea exploration and development, tactical surveillance, etc. Thus, robot control system construction used for underwater-robot like AUV or ROV is essential in these areas. In this paper, we propose the Message Merging MAC($M^2$-MAC) protocol, which is suitable for real time robot control system, considering energy efficiency in important parts of underwater acoustic sensor network constitution. In this proposed MAC protocol, gateway node receives the data from robot nodes according to the time slots that were allotted previously. And messages delivered from base-station are generated to one MAC frame by buffering process. Finally, generated MAC frames are broadcasted to all robot nodes in the cluster. Our suggested MAC protocol can also be hybrid MAC protocol, which is successful blend of contention based and contention-free based protocol through relevant procedure with Maintenance&Sleep (M&S) period, when new nodes join and leave as an orphan. We propose mathematical analysis model concerned about End-to-End delay and energy consumption, which is important factor in constructing real-time robot control system. We also verify the excellence of performance according to comparison of existing MAC protocols with our scheme.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.12
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• pp.83-88
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• 2008

The QPP interleaver has been gaining attention since it provides contention-free interleaving functionality for high speed parallel turbo decoders. In this paper we first show that the quadratic term $f_2x^2%K$ of $f(x)=(f_1x+f_2x^2)%K$, the address generating function, is periodic. We then introduce a low-power address generator which utilizes this periodic characteristic. This generator follows the conventional method to generate the interleaving addresses and also to save the quadratic term values during the first half of the first period. The saved values are then reused for generating further interleaved addresses, resulting in reduced number of logical operations. Power consumption is reduced by 27.38% in the design with fixed-K and 5.54% in the design with unfixed-K on average for various values of K, when compared with the traditional designs.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.9
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• pp.19-28
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• 2010

The GTS(Guaranteed Time Slot) of the IEEE 802.15.4 standard, which is the contention free access mechanism, is used for low-latency applications or applications requiring specific data bandwidth. But it has some problems such as delay of service due to FIFS(First In First Service) scheduling. In this paper, we proposes a weight based GTS allocation scheme for fair queuing in IEEE 802.15.4 LR-WPAN. The proposed scheme uses a weight that formed by how much more weight we give to the recent history than to the older history for a new GTS allocation. This scheme reduces service delay time and also guarantees transmission simultaneously within a limited time. The results of the performance analysis shows that our approach improves the performance as compared to the native explicit allocation mechanism defined in the IEEE 802.15.4 standard.