• Journal of information and communication convergence engineering
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• v.2 no.4
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• pp.224-227
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• 2004

The purpose of this paper is to theoretically analysis of performance of MRC diversity for detection of M-ary signals on the Rician fading channels. To do it, the difference between the approximation to bit error probability and the exact bit error rate (BER) in evaluating the performance of MPSK signals is investigated by numerical analyses. In addition, the performance evaluation of MDPSK signals in the independent branch diversity is performed by an integral-form expression in case of when MDPSK signal in MRC system is experiencing the Rician fading.

• Journal of information and communication convergence engineering
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• v.7 no.2
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• pp.182-184
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• 2009

In this letter, we derive a tight closed-form formula for an ergodic capacity of a multiple-input multiple-output (MIMO) for the application of wireless communications. The derived expression is a simple closed-form formula to determine the ergodic capacity of MIMO systems. Assuming the channels are independent and identically distributed (i.i.d.) Rayleigh flat-fading between antenna pairs, the ergodic capacity can be expressed in a closed form as the finite sum of exponential integrals.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.165.2-165
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• 2001

A number of previous researches in evolutionary algorithm are based on the study of facets we observe in natural evolution. The individuals of species in natural evolution occupy their own niche that is a subdivision of the habitat. This means that two species with the similar requirements cannot live together in the same niche. This is known as the competitive exclusion principle, i.e., complete competitors cannot coexist. In this paper, a new evolutionary programming algorithm adopting this concept is presented. Similarly in the case of natural evolution , the algorithm Includes the concept of niche obtained by partitioning a search space and the competitive exclusion principle performed by migrating individuals. Cell partition and individual migration strategies are used to preserve search diversity as well as to speed up convergence of an ...

• Electronics and Telecommunications Trends
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• v.26 no.4
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• pp.31-42
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• 2011

지상파 DMB 서비스가 시작된지 5주년을 맞은 지난해 12월, 누적단말판매량이 4천만 대를 넘는 것으로 추산되는 등 지속적인 성장을 보이고 있지만 정작 서비스를 제공하는 지상파 DMB 방송 사업자는 광고 및 채널 임대 외에 특별한 수익모델을 찾지 못해 고전하고 있다. 지상파 DMB 전체 광고매출이 2006년 약 17억 원에서 2010년 약 210억 원 정도로 꾸준히 늘고 있지만 사업 규모에 비해 턱없이 부족한 실정이고 모바일 IPTV, 스마트폰의 등장으로 새로운 환경 변화에 적응해야 하는 어려움도 있다. 본 고에서는 스마트 모바일 DMB라는 이름으로 방송통신 융합 측면에서 지상파 DMB 서비스의 변화에 대한 동향을 살펴보고자 한다. 방송 사업자와 통신 사업자가 협력을 통해 서비스를 제공한 DMB2.0 서비스, 스마트폰과의 동거를 시작하는 스마트 DMB 서비스를 살펴보고 올해부터 기술개발이 추진되는 스마트 모바일 하이브리드 DMB를 소개한다.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.837-840
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• 1999

In this paper, we design and verify the hardware circuit that performs PLCP(Physical Layer Convergence Protocol) protocol functions of physical layer in IEEE 802.11 frequency hopping WLAN(Wireless Local Area Network). Altera MAX＋PLUS I $I^{〔1〕}$ is used as a design tool. The designed circuit consists of control register module to interface with upper layer, FIFO module to transmit/receive data with upper layer, TX function module, and RX function module. It is verified that the developed circuit conforms well to the IEEE 802.11 standard specification and can support both 1Mbps and 2 Mbps transmission rate by simulation. The developed circuits can be utilized for the implementation of protocol processor in wireless LAN areas.

• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.2
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• pp.57-64
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• 1993

A modified kinematic wave model of the overland flow in vegetated filter strips was developed. The model can predict both flow depth and hydraulic radius of the flow. Existing models can predict only mean flow depth. By using the hydraulic radius, erosion, deposition and flow's transport capacity can be more rationally computed. Spacing hydraulic radius was used to compute flow's hydraulic radius. Numerical solution of the model was accomplished by using both a second-order nonlinear scheme and a linear solution scheme. The nonlinear portion of the model ensures convergence and the linear portion of the model provides rapid computations. This second-order nonlinear scheme minimizes numerical computation errors that may be caused by linearization of a nonlinear model. This model can also be applied to golf courses, parks, no-till fields to route runoff and production and attenuation of many nonpoint source pollutants.

• Journal of Industrial Convergence
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• v.13 no.4
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• pp.1-10
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• 2015

The purpose of this study is to propose a model built on the theoretical foundation of ecological sensitivity applicable to group and coaching process for organization members in industry management environment. For this, I have looked into theoretical foundation basis-foundation required for the ecological sensitivity process based on ecological discourse, based on which I have proposed a process model. The ecological basis-foundation with regards to ecological sensitivity dealt with in this paper includes 1)Crisis awareness, 2)Acquisition of ecological unconsciousness, 3)Fostering green imagination and 4)Setting targets.

• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.370-374
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• 2013

The effects of zinc chloride addition on pore development of porous carbon nanofibers prepared by polyacrylonitrile (PAN)/ N,N'-dimethylformamide (DMF) (10 wt%) electrospinning were investigated. The change of morphological and structural modification by zinc chloride activation was investigated by a scanning electron microscopy (SEM) analysis. $N_2$ adsorption isotherm characteristics at 77 K were confirmed by Brunauer-Emmett-Teller (BET) and Horvath-Kawazoe (H-K) equations, and the curves showed the Type I mode in the International Union of Pore and Applied Chemistry (IUPAC) classification, indicating that lots of micropores exist in the sample. In addition, specific surface areas and total pore volumes of porous carbons prepared by the zinc chloride activation were determined as 600~980 $m^2/g$ and 0.24~0.40 $cm^3/g$, respectively. As experimental results, many holes or demolished structures were found on the fiber surfaces after the zinc chloride activation as confirmed by a SEM analysis. It was also observed that various pore sizes were found to be depended on the adding content of zinc chloride in PAN/DMF solution in this system.

• Membrane Journal
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• v.31 no.6
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• pp.443-455
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• 2021

In this study, polyphenylene sulfide (PPS) was used as a support and a separator was manufactured using polysulfone and inorganic additives to manufacture a separator with low membrane resistance for application of an alkali water electrolysis system, and then the effect on the thickness and porosity of the support was analyzed. The PPS felt used as a support was compressed with variables of temperature (100℃, 150℃, 200℃) and pressure (1 ton, 2 tons, 3 tons, 5 tons) to adjust the thickness. A porous separator could be manufactured by preparing a slurry with polysulfone using BaTiO₃ and ZrO₂ which have high hydrophilicity and excellent alkali resistance as inorganic particles and casting the slurry on a compressed PPS felt. Changes in morphology of the separator according to compression conditions were confirmed through an electron scanning microscope (SEM). After that, the porosity was calculated, and the thickness and porosity tended to decrease as the compression conditions increased. Various characteristics were evaluated to confirm whether it could be used as a separator for water electrolysis. As a result of measuring the mechanical strength, it was confirmed that the tensile strength gradually increased as the compression conditions (temperature and pressure) increased. Finally, it was confirmed that the porous separator manufactured through the alkali resistance test has excellent alkali resistance, and through the IV test, it was confirmed that the membranes compressed at 100℃ and 150℃ had a lower voltage and improved performance than the existing uncompressed membrane.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.5
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• pp.654-666
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• 2019

The tactical network has several different characteristics compared with commercial internet network such as hierarchical topology, dynamic topology changing and wireless link based connectivity. For considering IP mobility management in the tactical network, current mobility management using Mobile IP(MIP) is not suitable with some reasons such as non-optimal routing paths and single point of failure. Proxy Mobile IP(PMIP) which supporting network-based mobility in hierarchical manner can provide optimal routing path in the tactical network environment, but centralized anchor is still remained a threat to the stability of the tactical network which changes its topology dynamically. In this paper, we propose PMIP-based distributed mobility management for the tactical network environment. From our design, routing paths are always configured in optimized way, as well as path is recovered quickly when the mobility anchor of user is failed. From numerical analysis, comparing to other mobility scheme, result shows that the proposed scheme can reduce packet transmission cost and latency in tactical network model.