• Journal of Communications and Networks
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• 제17권4호
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• pp.440-448
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• 2015

In this paper, we study the problem of selfish behavior of secondary users (SUs) based on cognitive radio (CR) with the presence of primary users (PUs). SUs are assumed to contend on a channel using the carrier sense multiple access with collision avoidance (CSMA/CA) and PUs do not consider transmission of SUs, where CSMA/CA protocols rely on the random deference of packets. SUs are vulnerable to selfish attacks by which selfish users could pick short random deference to obtain a larger share of the available bandwidth at the expense of other SUs. In this paper, game theory is used to study the systematic cheating of SUs in the presence of PUs in multichannel CR networks. We study two cases: A single cheater and multiple cheaters acting without any restraint. We identify the Pareto-optimal point of operation of a network with multiple cheaters and also derive the Nash equilibrium of the network. We use cooperative game theory to drive the Pareto optimality of selfish SUs without interfering with the activity of PUs. We show the influence of the activity of PUs in the equilibrium of the whole network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권9호
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• pp.2101-2119
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• 2013

The spectrum allocation is an attractive issue for mobile cognitive radio (CR) network. However, the time-varying characteristic of the spectrum allocation is not fully investigated. Thus, this paper originally deduces the probabilities of spectrum availability and interference constrain in theory under the mobile environment. Then, we propose a prediction mechanism of the time-varying available spectrum lists and the dynamic interference topologies. By considering the node mobility and primary users' (PUs') activity, the mechanism is capable of overcoming the static shortcomings of traditional model. Based on the mechanism, two prediction-based spectrum allocation algorithms, prediction greedy algorithm (PGA) and prediction fairness algorithm (PFA), are presented to enhance the spectrum utilization and improve the fairness. Moreover, new utility functions are redefined to measure the effectiveness of different schemes in the mobile CR network. Simulation results show that PGA gets more average effective spectrums than the traditional schemes, when the mean idle time of PUs is high. And PFA could achieve good system fairness performance, especially when the speeds of cognitive nodes are high.

• 항공우주기술
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• 제12권2호
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• pp.91-98
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• 2013

LEO (Low Earth Orbit), GEO (Geosynchronous Earth Orbit) 위성을 비롯한 우주 탐사선의 컴퓨팅 환경은 지상의 내장형 시스템(Embedded System)과 동일한 범주로 간주될 수 있으며 개인용, 산업/서버용 컴퓨터와 비교했을 때 비교적 원시적이고 발전 속도도 더뎠다. 특히 개인 컴퓨터 및 서버/워크스테이션에서 필수적으로 사용되고 있는 파일 시스템도 우주 탐사선에는 최근까지 거의 사용되지 않았다. 본 논문에서는 최근에 우주 탐사선에 파일 시스템을 적용하기 위한 유럽 PUS (Packet Utilization Standard)와 CCSDS (Consultative Committee for Space Data Systems) 커뮤니티의 관련 규격 제정 등 국제적 연구 개발 동향 및 우주 탐사선에 적용가능한 응용 기술 분야에 대한 연구 결과를 기술한다.

• 약학회지
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• 제49권1호
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• pp.11-19
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• 2005

The root of Astragalus membranaceus (Leguminosae) has been used in traditional chinese prescriptions for strengthning the superficial resistance, promoting pus discharge and tissue regeneration, diuretis and alleviating edema. Lipid peroxidation has been suggested as a major cause of atherosclerosis, cancer, liver disease, and the aging process. In order to investigate the anti-lipid peroxidation activity, Astragali Radix was extracted with $80\%$ MeOH and fractionated with hexane, $CH_{2}Cl_2$, EtOAc, BuOH and Water. The antilipid peroxidation activities of them were determined by human erythrocyte ghost and $CCl_4$-induced lipid peroxidation. $CH_{2}Cl_2$ and EtOAc fractions, especially, isoflavonoids, 7,2'-dihydroxy-3',4'-dimethoxyisoflavan-7-O-${\beta}$-D-glucoside and calyco sin-7-O-${\beta}$-D-glucoside from EtOAc fraction showed anti-lipid peroxidation activities.

• Advances in Traditional Medicine
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• 제4권4호
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• pp.261-266
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• 2004

Wound swabs and pus samples were collected from diabetic foot ulcers, and control pus samples from non-diabetic cases. In 144 diabetic cases screened, Pseudomonas aeruginosa was isolated from 78 cases, in which 10.59% of the isolates were multidrug resistant (MDR), whereas the 60 control cases were not MDR. The isolated bacteria were decreasingly resistant to 6 clinically administrated antimicrobics such as ceftazidime, gentamicin, ciprofloxacin, tobramycin, piperacillin and amikacin. Therefore, it is demanded that new and more effective antimicrobials of phytochemical origins are sought after. Among 11 isoflavones (YS11-YS21) isolated from Sophora and Euchresta (Leguminosae; pea plant family), 2 (YS19 and YS21) prominently exhibited the high antibacterial activity both in vitro and in vivo. By the preliminary results, the object of this paper is to evaluate the in vitro antibacterial effect of YS19 and YS21 on the clinically isolated bactera of Ps. Aeruginosa in hospitals. All the isolates were sensitive to YS19 and YS21 and for both, minimum inhibitory concentration (MIC) values ranged from $2\;to\;50\;{\mu}g/mL$. The $MIC_{90}$ values of YS19 and YS21 were $50\;{\mu}g/mL$. It is suggested that these isoflavones might consist a basis phytochemical prevention and therapy for diabetic foot infections caused by pseudomonads.

• 한국임상수의학회지
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• 제11권1호
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• pp.479-484
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• 1994

An English Bulldog 4 years old, Queen was hospitalized three weeks after mating as anorexia, decreased activity, hamorrhagic pus like vaginal discharge, and high fever. It was very difficult to diagnose by clinical signs and clinical pathological findings, at the first. Eenlarged uterus cavity, fluid accumulation in uterus was clearly identified by radiography and ultrasonography. The results suggest that X-ray and ultrasound is very important diagnostic method for pyometra to know disease progress.

• 한방안이비인후피부과학회지
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• 제21권1호
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• pp.70-82
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• 2008

Objective : The purpose of this study is to examine the effects of Baickbujasan(BB) on the skin damage and depigmentation. Method : The inhibition of tyrosinase activity, melanogenesis and cell viability in cultured B16 melanoma cells were measured. In order to test effects of reduction of melanogenesis, B16 F-10 mouse melanoma stem line was employed to extract melanin from cultured cell, where BB was added or not, and was dissolved in alkali for colorimetric analysis. Also, in order to test skin alteration in C57BL/6 after UV irradiation, the animals were grouped into a UV urradiation group and UV irradiation after BB application group. Dopa oxidase tissue staining was excuted to invesitage the change in the distribution of active melanin cell. The distribution of active melanin cell in inner skin of iNOS after damage from UVB irradiation and the manifestation condition of P53 which takes part in natural death of keratinocyte were examined. Result : The results indicate that BB has significant effects on tyrosinase activity, and melanogenesis in vivo test. BB seems to reduce C57BL/6, external dermatological damage, for instance, erythematous papule, eczema, loss of keratinocyte, reduction in pus, and relieves dermatological damages. Conclusion : BB can be applied externally for UV protection and depigmentation.

• Journal of Communications and Networks
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• 제17권4호
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• pp.406-418
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• 2015

Cognitive radio networks (CRNs) have emerged as a promising solution to the problem of spectrum under utilization and artificial radio spectrum scarcity. The paradigm of dynamic spectrum access allows a secondary network comprising of secondary users (SUs) to coexist with a primary network comprising of licensed primary users (PUs) subject to the condition that SUs do not cause any interference to the primary network. Since it is necessary for SUs to avoid any interference to the primary network, PU activity precludes attempts of SUs to access the licensed spectrum and forces frequent channel switching for SUs. This dynamic nature of CRNs, coupled with the possibility that an SU may not share a common channel with all its neighbors, makes the task of multicast routing especially challenging. In this work, we have proposed a novel multipath on-demand multicast routing protocol for CRNs. The approach of multipath routing, although commonly used in unicast routing, has not been explored for multicasting earlier. Motivated by the fact that CRNs have highly dynamic conditions, whose parameters are often unknown, the multicast routing problem is modeled in the reinforcement learning based framework of learning automata. Simulation results demonstrate that the approach of multipath multicasting is feasible, with our proposed protocol showing a superior performance to a baseline state-of-the-art CRN multicasting protocol.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권9호
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• pp.3312-3334
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• 2015

In this paper, a mechanism for spectrum allocation in overlay cognitive radio networks is proposed. In overlay cognitive radio networks, the secondary users (SUs) must first sense the activity of primary users (PUs) to identify unoccupied spectrum bands. Based on their different contributions for the spectrum sensing, the SUs get payoffs that are computed by the fusion center (FC). The unoccupied bands will be auctioned and SUs are asked to bid using payoffs they earned or saved. Coalitions are allowed to form among SUs because each SU may only need a portion of the bands. We formulate the coalition forming process as a coalition forming game and analyze it by game theory. In the coalition formation game, debtor-creditor relationship may occur among the SUs because of their limited payoff storage. A debtor asks a creditor for payoff help, and in return provides the creditor with a portion of transmission time to relay data for the creditor. The negotiations between debtors and creditors can be modeled as a Bayesian game because they lack complete information of each other, and the equilibria of the game is investigated. Theoretical analysis and numerical results show that the proposed auction yields data rate improvement and certain fairness among all SUs.

• Journal of Periodontal and Implant Science
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• 제28권2호
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• pp.291-310
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• 1998

This study was performed to evaluate the effects of extracts of Drynariae Rhizoma on the characteristics of rat calvaria cells(RCV) and bone marrow cells(RBM) which have the important role on the bone formation in vitro. Drynariae Rhizoma has been known as the useful herbal medicament for treatment of the wound healing including regeneration of bone fracture, and also has been used to treat the periodontal lesions, tooth mobility, gingival bleeding and pus discharge via sulcus in Oriental Medicine. In control group, the cells were cultured alone with Dulbeco's Modified Eagle's Medium contained with 10% fetal bovine serum, 100U/ml penicillin, $100{\mu}g/ml$ streptomycin, $0.5{\mu}g/ml$ amphotericin-B. In experimental group, extracts of Drynariae Rhizoma(0.1, 1, 5, 10, $50{\mu}g/ml$) were added into the above culture condition. And then each group was characterized by examing the cell proliferation at 1, 3, 7, 14, 21, 30th day, the amount of total protein synthesis and alkaline phosphatase activity of RCV at 2,4th day and those of RBM at 3, 6th day. And also, the calcified nodule of RCV was examed at 3, 5th day in three goup, control, experimental, culture with the PDGF group. The results were as follow ; 1. Both RCV and RBM cells in Drynariae Rhizoma-treated experimental group proliferated more rapidly than nontreated control group. The experimental group below $5{\mu}g/ml$ Drynariae Rhizoma-treated showed more prominent cell proliferation from the 7th day to the 21st day than the control group and above $10\;{\mu}g/ml$ treated group in RCV. 2. Amount of total protein synthesis was more increased in Drynariae Rhizomatreated group than in control group. In $5{\mu}g/ml$ Drynariae Rhizoma-treated group showed most prominent protein synthesis of the any other exrperimental group and control group. 3. Alkaline phosphatase activity also more increased in Drynariae Rhizomatreated group than control group. 4. Mineralized nodules in Drynariae Rhizoma-treated group were more than not in control group but also in PDGF-treated group. From the above results, Drynariae Rhizoma appeared to enhanced the proliferation, protein synthesis, alkaline phosphatase activity and cellular ability of mineralized nodule formation than PDGF. So that, we conclude that Drynariae Rhizoma enhances the activities of bone cells which have the important role on the periodontal regeneration and optimal application of Drynariae Rhizoma was thought to be useful as the means in bone regeneration.