• Journal of information and communication convergence engineering
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• v.12 no.4
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• pp.199-207
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• 2014

A new cooperative MAC protocol called the busy tone cooperative medium access control (BT-COMAC) protocol is proposed to overcome the drawbacks and maximize the advantages of existing schemes. This scheme uses a new metric called decibel power to decide an appropriate helper node. Using received power strength is more efficient in selecting an appropriate helper node, especially in a densely populated network, than the effective transmission rates used in conventional schemes. All communication nodes in a communication service area are assumed to move independently. Two performance metrics are used: System throughput and channel access delay. A performance evaluation of the BT-COMAC protocol is conducted using a computer simulation over a slow fading wireless channel, and its performance results are compared with those of four existing schemes. The numerical results show that the BT-COMAC protocol improves the system throughput by approximately 15% as compared to the best existing scheme.

• Journal of the Korea Society for Simulation
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• v.21 no.2
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• pp.69-78
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• 2012

In this paper, a study on finding an appropriate helper node that can help increase effective frame transmission rate for cooperative communications at ad hoc networks is carried out. Those researches from reference use the reactive helper node selection mechanism which starts its role after exchanging RTS and CTS frames between source and destination nodes, and are implemented into our simulator for performance comparison. System throughput and average channel access delay are used for performance measures and all communicating nodes are assumed to move independently within the communication range. It is anticipated that this research result can be used as basic information for designing a new efficient helper node selection scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.8
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• pp.1811-1819
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• 2013

In this paper, we carried out a study on how to find an appropriate helper node for cooperative communications, the role of which is very import to enhance system throughput of wireless communication system. The busy tone cooperative MAC (BT-COMAC) protocol proposed in this paper is a new cooperative MAC protocol with a reactive helper node scheme and maximizes the benefits of existing schemes while making up for their shortcomings. We conducted performance evaluation of this new protocol using computer simulation experiment. System throughput in bps and channel access delay are utilized as performance measures. We used a random way point mobility model where every communication node moves independently one another, and slow fading channel where every communication node decided its transmission rate with received power basis. Numerical results show that the new MAC protocol enhances system throughput as much as 15% of the existing scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1684-1691
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• 2016

Erasure codes have recently been applied to distributed storage systems due to their high storage efficiency. Regenerating codes are a kind of erasure codes, which are optimal in terms of minimum repair bandwidth. An (n,k,d)-regenerating code consists of n storage nodes where a failed node can be recovered with the help of the exactly d numbers of surviving nodes. However, if node failures occur frequently or network connection is unstable, the number of helper nodes that a failed node can contact may be smaller than d. In such cases, regenerating codes cannot repair the failed nodes efficiently since the node repair process of the codes does not work when the number of helper nodes is less than d. In this paper, we propose an operating method of regenerating codes where a failed node can be repaired from ${\bar{d}}$ helper nodes where $$k{\leq_-}{\bar{d}}{\leq_-}d$$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1397-1405
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• 2012

Cooperative communications play a important role in increasing frame transmission rate at wireless communication networks where frequency resource is strictly limited. In this paper, we did a research on how to select the helper nodes that are very import in cooperative communications. As a prelude study in this research field, we carried out performance comparison of three helper node selection schemes using computer simulation. The system throughput was used as the performance measure and the random way point mobility model, where every communicating nodes move around within the designated communication range, was used.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.11
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• pp.2636-2656
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• 2013

To improve the cooperative efficiency of node cooperation and multiple access performance for multihop wireless networks, a priority-differentiated cooperative medium access control protocol with contention resolution (CRP-CMAC) is proposed. In the protocol, the helper selection process is divided into the priority differentiation phase and the contention resolution phase for the helpers with the same priority. A higher priority helper can choose an earlier minislot in the priority differentiation phase to send a busy tone. As a result, the protocol promptly selects all the highest priority helpers. The contention resolution phase of the same priority helpers consists of k round contention resolution procedures. The helpers that had sent the first busy tone and are now sending the longest busy tone can continue to the next round, and then the other helpers that sense the busy tone withdraw from the contention. Therefore, it can select the unique best helper from the highest priority helpers with high probability. A packet piggyback mechanism is also adopted to make the high data rate helper with packet to send transmit its data packets to its recipient without reservation. It can significantly decrease the reservation overhead and effectively improve the cooperation efficiency and channel utilization. Simulation results show that the maximum throughput of CRP-CMAC is 74%, 36.1% and 15% higher than those of the 802.11 DCF, CoopMACA and 2rcMAC protocols in a wireless local area network (WLAN) environment, and 82.6%, 37.6% and 46.3% higher in an ad hoc network environment, respectively.

• Journal of Internet Computing and Services
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• v.22 no.1
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• pp.51-63
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• 2021

Identifying characters who appear in a story and analyzing their relationships is essential to understanding the story. This paper aims to identify the two actants (or character roles) as Helper and Opponent in Greimas's Actantial model by identifying Subject (i.e., protagonist) and analyzing the emotional interactions between the Subject and the two actants (Helper/Opponent). Our proposed method consists of three steps. First, we identify objects (i.e., characters) appearing in the text story. Next, we extract relational information through the interaction of the characters, and then classify emotions in the text expressed as relational information. Finally, we represent the flow of emotional relations among characters as a directed graph. The node with the highest degree is considered as the Subject because it includes the most relational information. The node that sends the most positive/negative emotions to the Subject is considered as the Helper/Oppenent, respectively. Our research contributes to the computer-based narrative understanding by providing a computational method that automatically extracts the three key character roles (Subject, Helper, and Opponent) from the text story.

• THE JOURNAL OF KOREAN ORIENTAL ONCOLOGY
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• v.4 no.1
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• pp.89-110
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• 1998

Yookmijihwangtang has been widely used oriental herb prescriptions, which is healing some discuss that come from insufficiency of innate essence and deficiency of kidney Ki. The meaning of healing discusses tonification of insufficient innate essence and insufficient kidney Ki can be regarded as reinforcement of wholely power of keeping homeostasis, that is correlated with immuno-responsibility which protects subject from outer antigen to keep normal vital condition. This study was aimed to investigate correlative effects of Yookmijihwangtang water abstract on the RBC, WBC, blood CD4+ T helper cell count, blood testosterone, blood cAMP and blood cortisol. 40 Sprague-Dawley male rats were divided into 5 groups(Normal, Control, Sample I, Sample II, Sample III), 6 animals in every group. Normal group was not treated anything, control group was administrated normal saline in the same dosage of Sample I. 3 Sample groups were received some of Yookmijihwangtang water abstract at one time per 24 hours during 5 days in different dosage. Sample I(1/310pack/ml), Sample II(1/62pack/ml), Sample III(1/2.4pack/ml). After finishing treatment, all experimental subjects were killed for blood sample on RBC, WBC, blood CD4+ T helper cell count, spleen CD4+ T helper cell count, axillary lymph node CD4+ T helper cell count. blood cAMP, blood testosterone and blood cortisol. The results were as follows; RBC and WBC were increased in all sample groups. Blood CD4+ T helper cell count(CD4+ T cell count in the blood/whole lymphocyte count in the blood ${\times}100%$) was Normal $46.17{\pm}5.88$, Control $44.50{\pm}4.37$, Sample I $53.00{\pm}2.28$, Sample II $53.83{\pm}3.87$, Sample III $52.17{\pm}2.93$. By the 95% Duncan ANOVA all experimental groups(sample I, Sample II, Sample III) showed slight significant difference from Normal and Control. Blood cAMP(nmol/l) were Normal $1.12{\pm}0.17$, Control $1.16{\pm}0.32$, Sample I $0.46{\pm}0.07$, Sample II $0.44{\pm}0.04$, Sample III $0.54{\pm}0.04$. All experimental groups were singificantly different from both Normal and Control groups(p<0.05). Blood cortisol(nl/ml) were Normal $100.00{\pm}2.00$ Control $90.00{\pm}4.00$, Sample I $440.00{\pm}5.00$, Sample II $520.00{\pm}40.00$, Sample III $470.00{\pm}7.00$. Blood cortisol of all experimental groups were significantly increased(p<0.05). The results suggest that Yookmijihwangtang water abstract could be administrated to patients who have some diseases insufficient essence.

• The Journal of Dong Guk Oriental Medicine
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• v.6 no.2
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• pp.99-107
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• 1998

Cyclosporin A(CsA) is a selective immunosuppressive agent that has been credited with improved survival of solid organ allografts. Lymph node of BALB/C mouse administered CsA immunohistochemically observed to understand immunosuppressive effects of CsA on T lymphocytes, IL-2 receptors, and natural killer NK cells in lymph node. CsA orally administered daily for 10days at the dose 45mg/kg/day/. The lymph node were obtained at day 3, 7, and 14 after CsA administration and embedded with paraffin, and then stained by following ABC method that used monoclonal antibody including L3T4(CD4), Ly2(CD8), IL-2R(CD25), and NK-1.1(CD56). There were little changes of reactive degree and number of helper T lymphocytes, cytotoxic T lymphocytes, IL-2 receptors, and NK cells at day 3 after CsA administration, but they began to decrease at day 7. These decrease were greatest at day 14. The helper T lymphocytes. cytotoxic T lymphocytes, IL-2 receptors, and NK cells distributed in paracortex and medullary sinus. These results indicated that the secretion of IL-2 began to decrease at day 7 after CsA administration and subsequently to suppress T lymphocytes and NK cell as components of cell-mediated immunity.

• The Journal of Dong Guk Oriental Medicine
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• v.7 no.1
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• pp.33-41
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• 1998

Lymph node tissues of BALB/C mouse treated with DNCB were immunohistochemically observed to investigate the activation of cell mediated immunity in lymph node of murine with allergic contact dermatitis. The inguinal region of BALB/C mice were sensitized by one application of $25{\mu}l$ of 5% 2,4-dinitrochlorobenzene(DNCB) onto an abdominal skin and 2 weeks later, the mice were challenged with $4{\mu}l$ of 2.5% DNCB. The inguinal lymph node were obtained at hour 24, 48, and 72 after 2nd DNCB treatment and embedded with paraffin, and then stained by following ABC method that used monoclonal antibody including L3T4(CD4), Ly2(CD8), IL-2R(CD25). The distribution of helper T lymphocytes, cytotoxic T lymphocytes and IL-2 receptors began to increase at hour 24 after after 2nd DNCB treatment and these increase appeared in paracortical area and medullary sinius. These increase were greatest at hour 48. These results indicated that the IL-2 secretion began to increase by activation of helper T lymphocytes in lymph node of DNCB re-exposure area and subsequently to activate suppress T lymphocytes.