• Journal of Korea Multimedia Society
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• v.10 no.12
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• pp.1622-1631
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• 2007

To realize the wireless packet scheduler which efficiently considers both the effect of adaptive modulation and coding (AMC) scheme due to variable wireless communication channel information from physical layer and the QoS differentiation of multimedia services from internet protocol (IP) layer, this paper proposes a new downlink AMC-based priority queuing (APQ) scheduler which combines AMC scheme and service priority method in multimedia services at the same time. The result of numerical analysis shows that the proposed APQ algorithm plays a role in increasing the number of services satisfying the mean waiting time requirements per each service in multimedia services because the APQ scheme allows the mean waiting time of each service to be reduced much more than existing packet scheduler having only user selection processor.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6B
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• pp.586-592
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• 2002

In this paper, new channel scheduling algorithms which reduce transmission delay caused by wireless network are proposed in AMC/TDM wireless data communication. The concept of the Proposed algorithms is based on the proportional fairness, M-LWDF, and performance-guaranteeing algorithm proposed by Xin Liu. The proposed algorithm can be applied to QoS guaranteeing services as well as best-effort services. Simulation results show that new algorithm reduced transmission delay upto 11.5% in case of proportional fairness algorithm and also decreased transmission delay unto 9% in case of M-LWBF algorithm.

• Journal of Satellite, Information and Communications
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• v.4 no.1
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• pp.28-35
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• 2009

We investigate the adaptive channel attenuation compensation of satellite OFDMA downlink users for minimum PAR (Peak to Average power Ratio), which is one of the main challenging issues in satellite OFDMA application. First, we analyze and compare PAR performances of two main different channel attenuation compensation schemes for OFDMA, i.e., PC-OFDMA (power control OFDMA) and AMC-OFDMA (Adaptive Modulation and Coding). While AMC-OFDMA maintains the constant transmission powers through entire user data subcarriers, PC-OFDMA has non-uniform subcarrier transmission powers because subcarrier powers are separately controlled to compensate each user's sub-channel attenuation. We newly found the fact that non-uniform subcarrier power in PC-OFDMA achieves rather reduced PAR compared to AMC-OFDMA and the amount of reduction becomes larger as the power differences among subcarriers increase. Also, there is an additional PAR reduction in PC-OFDMA by optimizing subcarrier grouping scheme for user's sub-channelization.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.7-12
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• 2010

The bandwidth of a Jerusalem AMC was investigated based on the equivalent circuit model. Using the circuit model and the derivative of the admittance(Y'), the relation between the bandwidth and various circuit parameters was analyzed. It was shown that the substrate thickness and permeability enhance the bandwidth whereas the loadings on FSS grid degrade the bandwidth. Among the two loadings, the capacitive loading had better bandwidth characteristics than the inductive loading. AMC with single polarization was suggested to relax the bandwidth degradation by the inductive loading.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4B
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• pp.270-277
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• 2006

In the wireless adaptive modulation and coding(AMC) systems, the modulation type of user's connection can be changed dynamically. and the ongoing connection might fail due to the change of modulation. In this paper, we approach the AMC-induced CAC problem by focusing on the guaranteed connection. Three kinds of calls, new, handoff, and modulation-changed calls, are considered. We propose a modified guard channel CAC scheme that allows the modulation-changed and handoff calls to use the guard channel. Then we analyze a Markov model for the CAC scheme with long-term AMC in mind. According to the simulation results, the proposed approach reduces the call dropping probability for modulation-changed calls, which suggests the threshold of guard channels can be determined based on the proposed approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.9
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• pp.744-750
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• 2013

In this paper, we proposed new type of an artificial magnetic conductor(AMC) structure, which has a high impedance surface for realizing the meta-material characteristics. The designed AMC structure set a goal of 3.2GHz, and the reflector, which consists of periodically arrayed AMCs is fabricated and measured. The high impedance improves the reflection coefficient, decreases the system size and interference, and increases the antenna performance. The structure has embodied the high impedance by the thickness and relative permitivity of the dielectric substrate and the design configuration without the metallic via hole which connects the AMC to the GND. The bandwidth is 150% broader than the similar AMC structures. Also, the distance between the antenna and the AMC reflector is decreased by ${\lambda}/10$ as working as the metal(PEC) reflectors. The antenna radiation characteristics are 3dB increased at 10mm away from reflector by measurement. The proposed reflector could be inserted in the portable mobile devices, and the antenna's performance has improved by the reflector. The specific absorption rate is dramatically decreased over 94% because the back radiation of the antenna is shielded.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.519-535
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• 2012

In order to establish a rainfall-runoff model, calibration of hydrological parameters for the model is very important. Especially, Curve Number(CN), estimated by NRCS method, is a main factor to apply unit hydrograph theory to calculation of peak discharge. For using NRCS method, it is needed selecting AMC because CN is strongly connected with that. In this study, we focus our concern on finding a applicable standard for selecting AMC for CN. For this, three dams which are Boryeong, Habchon, Namgang are selected as target basins to use observed data including rainfall and dam inflow. As a result of this research, it is found that CN must be included as a calibrated parameter to calculate effective rainfall for the rainfall-runoff model. Also, it is preferred to use PWRMSE of HEC-HMS program as a objective function for optimizing hydrological parameters. From the analyzing result of variation of AMC for peak discharge, it is recommended to apply AMC-III to estimation of CN for calculating effective rainfall of design hydrograph.

• Journal of Veterinary Clinics
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• v.19 no.1
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• pp.19-22
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• 2002

The examination with 96 bacteria isolates for antibiotics susceptibility was resulted in exploring many antibiotics resistance isolates from the diseased fishes. Vibrio sp. isolates were demonstrated over 90% resistances for Penicillin (P), Amoxicillin (Amc), Erythromycin (I), Colistin (CL). Streptomycin (S). Novobiocin (NV) and Neomycin(N), these isolates were, however, appeared over 80% susceptibilities for Norfloxacin (Nor), CE and UB. In Edwardsiella tarda case, 90 to 100% high resistance was observed for P, Doxycycline (Do), Tetracyclin (Te), Oxytetracycline (T), E, CL, Sulfamethoxasoletrimetoprim (SXT), S, Oxolinic acid (OA), W, Neomycin(N), on the contrary, 90 to 100% high susceptibilities was found for Amc, Nor, Ciprofloxacin (Cip), Orbifloxacin (ORB), Enrofloxacin (ENR), Flumeguine (UB) and NA. CL, Pefloxacin (PEF),S, Flumeguine (UB), OA, NA, NV N was exhibited 90 to 100% resistances for Streptococcus sp., on the other hand, 100% susceptible to AMC and 80% susceptible to Do, Te, ENR and UB was recognised. Lastly, Photobacterium damsela subsp. piscicida was showed 100fe susceptible to Amc and 86% susceptible to NOR, CIP ENR and UB. As a consequence, fish bacterial pathogens isolated from Kyeongnam area, especially Tongyeong-si, Geoje-si, and Goseong-gun, were showed highly resistant to a variety of antibiotics available in the field.

• Journal of Internet Computing and Services
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• v.8 no.1
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• pp.47-55
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• 2007

In this paper, we propose and observe a system that adopts Common-MCS (Modulation and Coding Scheme) level over all layer and Independent-MCS level for each layer in the combined AMC-V-BLAST (Adaptive Modulation and Coding-Vertical-Bell-lab Layered Space-Time) system. Also, comparing with the combined system using Common-MCS level, we observe throughput performance improvement in case of Independent-MCS level. As a result of simulation, Independent-MCS level case adapts modulation and coding scheme for maximum throughput to each channel condition in separate layer, resulting in improved throughput compared to Common-MCS level case. Especially, the results show that the combined AMC-V-BLAST system with Independent-MCS level achieves a gain of 700kbps in $7{\sim}9dB$ SNR (Signal-to-Noise Ratio) range against using Common-MCS level. In addition, the combined AMC-V-BLAST system using MMSEnulling method with receive diversity is verified that the difference of throughput between Independent MCS level system and common MCS level system in $7dB{\sim}9dB$ SNR is about 350kbps more or less.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.288-288
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• 2011

최근 들어 관측된 강우-유출 사상으로부터 유출곡선지수(Runoff curve number, CN)를 계산하는 연구가 수행되어왔으며, 이것은 기존 선행토양함수조건(Antecedent Moisture Condition; AMC) 을 이용한 유출곡선지수 적용에 대한 여러 문제점(AMC 기준의 타당성, 초기손실우량과 최대잠재보유수량의 비($I_a$ S=0.20의 적정성))이 부각되면서 선행유출조건을 이용한 유출곡선지수가 제안되었다. 본 연구에서는 선행유출조건(Antecedent Runoff Condition, ARC) 방법을 적용하여 IHP유역인 방림과 상안미 유역의 강우-유출자료로부터 CN을 직접 산정하였다. 먼저 방림과 상안미 유역에서 각각 12개, 10개의 관측된 강우-유출 사상을 통해 초기손실우량과 최대잠재보유수량의 비($I_a$/S)가 기존 가정의 0.20보다 작은 것을 확인하고 수정된 $I_a$/S비를 고려하여 대상 유역에서의 적정 CN을 산정하였다. 실제 강우-유출 사상에서 산정한 각 사상별 CN의 대표값을 찾기 위해 ARC-II의 평균유출조건으로 가정하여 각 사상별 단순평균과 4개의 지속기간(4시간, 3시간, 2시간, 1시간)별로 구분하여 평균한 CN을 구분하였다. 이를 통해 계산된 유효우량과 관측 유효우량과 비교를 실시하였으며 각 사상을 단순 평균한 ARC-II 조건으로 가정하여 계산된 CN의 오차가 가장 작은 것으로 나타났다. 따라서 기존의 선행토양함수조건(Antecedent soil moisture condition, AMC)의 CN으로 산정된 유효우량과 ARC조건으로 산정된 유효우량을 비교한 결과 방림유역에서 는 오차가 ARC 방법의 경우 37.76%, AMC 방법의 경우 51.27%로 평가되었고 상안미 유역에서는 오차가 ARC의 경우 31.97%, AMC 방법의 경우43.08%로 두 유역에서 모두 ARC 방법으로 산정된 CN이 더 적은 오차값을 주었다. 따라서 방림과 상안미 유역에서의 ARC로 산정된 CN값은 유효우량 산정의 정확성을 향상시킬 수 있으리라 판단된다.