• 제목/요약/키워드: EA performance

검색결과 132건 처리시간 0.021초

진폭비 섭동에 의한 cross-eye 재밍에 대한 수치적분 기반 성능분석 (Numerical Integration-based Performance Analysis of Cross-eye Jamming Algorithm through Amplitude Ratio Perturbation)

  • 김제안;최윤주;이준호
    • 한국융합학회논문지
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    • 제12권12호
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    • pp.59-64
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    • 2021
  • 본 논문에서는 기계적 결함에 따른 실제 진폭비와 명목상 진폭비의 차이를 정규분포를 갖는 랜덤변수로 모델링할 때, crosse-eye의 재밍 효과의 성능 분석을 다룬다. 수치 적분 기반 접근법을 사용하여 구한 mean square difference (MSD)를 제안한다. 수치 적분 기반 접근법을 사용하여 구한 MSD는 1차 테일러 근사 기반성능 분석 방법과 2차 테일러 근사 기반 해석적 성능 분석 방법을 이용하여 계산한 analytic 기반 MSD보다 근사하지 않은 Monte-Carlo 기반 Simulation MSD에 가깝다. 이는 수치 적분 기반 MSD가 정확성이 더 높은 것을 뜻한다. 계산비용이 큰 Monte-Carlo 기반 Simulation을 이용하지 않아도 수치적분을 통하여 MSD로 주어지는 진폭비 섭동이 성능 저하에 미치는 영향을 구할 수 있음을 보인다.

Glass Dissolution Rates From MCC-1 and Flow-Through Tests

  • Jeong, Seung-Young
    • 한국방사성폐기물학회:학술대회논문집
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    • 한국방사성폐기물학회 2004년도 학술논문집
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    • pp.257-258
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    • 2004
  • The dose from radionuclides released from high-level radioactive waste (HLW) glasses as they corrode must be taken into account when assessing the performance of a disposal system. In the performance assessment (PA) calculations conducted for the proposed Yucca Mountain, Nevada, disposal system, the release of radionuclides is conservatively assumed to occur at the same rate the glass matrix dissolves. A simple model was developed to calculate the glass dissolution rate of HLW glasses in these PA calculations [1]. For the PA calculations that were conducted for Site Recommendation, it was necessary to identify ranges of parameter values that bounded the dissolution rates of the wide range of HLW glass compositions that will be disposed. The values and ranges of the model parameters for the pH and temperature dependencies were extracted from the results of SPFT, static leach tests, and Soxhlet tests available in the literature. Static leach tests were conducted with a range of glass compositions to measure values for the glass composition parameter. The glass dissolution rate depends on temperature, pH, and the compositions of the glass and solution, The dissolution rate is calculated using Eq. 1: $rate{\;}={\;}k_{o}10^{(ph){\eta})}{\cdot}e^{(-Ea/RT)}{\cdot}(1-Q/K){\;}+{\;}k_{long}$ where $k_{0},\;{\eta}$ and Eaare the parameters for glass composition, pH, $\eta$ and temperature dependence, respectively, and R is the gas constant. The term (1-Q/K) is the affinity term, where Q is the ion activity product of the solution and K is the pseudo-equilibrium constant for the glass. Values of the parameters $k_{0},\;{\eta}\;and\;E_{a}$ are the parameters for glass composition, pH, and temperature dependence, respectively, and R is the gas constant. The term (1-Q/C) is the affinity term, where Q is the ion activity product of the solution and K is the pseudo-equilibrium constant for the glass. Values of the parameters $k_0$, and Ea are determined under test conditions where the value of Q is maintained near zero, so that the value of the affinity term remains near 1. The dissolution rate under conditions in which the value of the affinity term is near 1 is referred to as the forward rate. This is the highest dissolution rate that can occur at a particular pH and temperature. The value of the parameter K is determined from experiments in which the value of the ion activity product approaches the value of K. This results in a decrease in the value of the affinity term and the dissolution rate. The highly dilute solutions required to measure the forward rate and extract values for $k_0$, $\eta$, and Ea can be maintained by conducting dynamic tests in which the test solution is removed from the reaction cell and replaced with fresh solution. In the single-pass flow-through (PFT) test method, this is done by continuously pumping the test solution through the reaction cell. Alternatively, static tests can be conducted with sufficient solution volume that the solution concentrations of dissolved glass components do not increase significantly during the test. Both the SPFT and static tests can ve conducted for a wide range of pH values and temperatures. Both static and SPFt tests have short-comings. the SPFT test requires analysis of several solutions (typically 6-10) at each of several flow rates to determine the glass dissolution rate at each pH and temperature. As will be shown, the rate measured in an SPFt test depends on the solution flow rate. The solutions in static tests will eventually become concentrated enough to affect the dissolution rate. In both the SPFt and static test methods. a compromise is required between the need to minimize the effects of dissolved components on the dissolution rate and the need to attain solution concentrations that are high enough to analyze. In the paper, we compare the results of static leach tests and SPFT tests conducted with simple 5-component glass to confirm the equivalence of SPFT tests and static tests conducted with pH buffer solutions. Tests were conducted over the range pH values that are most relevant for waste glass disssolution in a disposal system. The glass and temperature used in the tests were selected to allow direct comparison with SPFT tests conducted previously. The ability to measure parameter values with more than one test method and an understanding of how the rate measured in each test is affected by various test parameters provides added confidence to the measured values. The dissolution rate of a simple 5-component glass was measured at pH values of 6.2, 8.3, and 9.6 and $70^{\circ}C$ using static tests and single-pass flow-through (SPFT) tests. Similar rates were measured with the two methods. However, the measured rates are about 10X higher than the rates measured previously for a glass having the same composition using an SPFT test method. Differences are attributed to effects of the solution flow rate on the glass dissolution reate and how the specific surface area of crushed glass is estimated. This comparison indicates the need to standardize the SPFT test procedure.

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Biguanide-Functionalized Fe3O4/SiO2 Magnetic Nanoparticles: An Efficient Heterogeneous Organosuperbase Catalyst for Various Organic Transformations in Aqueous Media

  • Alizadeh, Abdolhamid;Khodaei, Mohammad M.;Beygzadeh, Mojtaba;Kordestani, Davood;Feyzi, Mostafa
    • Bulletin of the Korean Chemical Society
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    • 제33권8호
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    • pp.2546-2552
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    • 2012
  • A novel biguanide-functionalized $Fe_3O_4/SiO_2$ magnetite nanoparticle with a core-shell structure was developed for utilization as a heterogeneous organosuperbase in chemical transformations. The structural, surface, and magnetic characteristics of the nanosized catalyst were investigated by various techniques such as transmission electron microscopy (TEM), powder X-ray diffraction (XRD), vibrating sample magnetometry (VSM), elemental analyzer (EA), thermogravimetric analysis (TGA), $N_2$ adsorption-desorption (BET and BJH) and FT-IR. The biguanide-functionalized $Fe_3O_4/SiO_2$ nanoparticles showed a superpara-magnetic property with a saturation magnetization value of 46.7 emu/g, indicating great potential for application in magnetically separation technologies. In application point of view, the prepared catalyst was found to act as an efficient recoverable nanocatalyst in nitroaldol and domino Knoevenagel condensation/Michael addition/cyclization reactions in aqueous media under mild condition. Additionally, the catalyst was reused six times without significant degradation in catalytic activity and performance.

ATM 시스템 경보 취합 장치 설계 및 개발 (Design and Development of an Alarm Gathering Interface Equipment for ATM Switching System)

  • 양충렬;김진태
    • 한국정보처리학회논문지
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    • 제3권7호
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    • pp.1845-1857
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    • 1996
  • ATM 경보 취합 장치는 $1,024\times1,024$의 대용량 ATM 교환기의 하드웨어 고장 취합 기능을 지원하기 위한 목적으로 8비트 소형 마이크로프로세서 및 EA-232C 통신 방법을 이용하여 AGLA(Alarm Gathering Interface board Assembly)로 부르는 단일 보드로 개발되었고, ATM 교환기를 구성하는 가가 서브시스템 하드웨어 블럭 및 모듈에 대해 온라인 시험을 통하여 성능이 입증되었다. 본 논문은 ATM 교환기의 하드웨어 장에 경보 신호의 관리를 위한 경보 취합 장치의 설계 및 개발에 관하여 기술하였으며 이는 추후 성능이 더욱 우수한 대용량 ATM 교환기의 유지 및 운용 기능을 개발하는데 이용될 수 있다. 아울러 ATM 교환기 경보 취합 비에 대한 향후 연구 항목을 제시하였다.

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직접 메탄올 연료전지용 PtRu/GNF 성능에 대한 화학적 처리의 영향 (Effect of Chemical Treatment on Performance Behaviors of PtRu/GNFs Catalysts for DMFCs)

  • 박수진;박정민
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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    • pp.369-372
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    • 2009
  • In the present study, the effect of chemical treatment on graphite nanofibers (GNFs) supports with various concentrated nitric acids was investigated for methanol oxidation. To optimize the electrocatalytic activity, PtRu catalysts were deposited on GNF supports by impregnation method. The surface and structural properties of the GNF supports were characterized by X-ray photoelectron spectroscopy (XPS), element analyzer (EA), and X-ray diffraction (XRD). The morphology of the catalysts was observed by means of transmission electron microscopy (TEM). The electrocatalytic activity of PtRu/GNF catalysts was investigated by cyclic voltammetry measurement. As a result, the oxygen functional groups were introduced on the GNF supports and were gradually increased with increasing of concentrated nitric acid, causing the smaller particle size and higher loading level. And the electrocatalytic activity of the catalysts for methanol oxidation was gradually improved. Consequently, it was found that chemical treatments could influence on surface properties of the carbon supports, resulting in enhancing the electrocatalytic activity of the catalysts for DMFCs.

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다목적 최적화를 위한 공생 진화알고리듬 (A Symbiotic Evolutionary Algorithm for Multi-objective Optimization)

  • 신경석;김여근
    • 한국경영과학회지
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    • 제32권1호
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    • pp.77-91
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    • 2007
  • In this paper, we present a symbiotic evolutionary algorithm for multi-objective optimization. The goal in multi-objective evolutionary algorithms (MOEAs) is to find a set of well-distributed solutions close to the true Pareto optimal solutions. Most of the existing MOEAs operate one population that consists of individuals representing the entire solution to the problem. The proposed algorithm has a two-leveled structure. The structure is intended to improve the capability of searching diverse and food solutions. At the lower level there exist several populations, each of which represents a partial solution to the entire problem, and at the upper level there is one population whose individuals represent the entire solutions to the problem. The parallel search with partial solutions at the lower level and the Integrated search with entire solutions at the upper level are carried out simultaneously. The performance of the proposed algorithm is compared with those of the existing algorithms in terms of convergence and diversity. The optimization problems with continuous variables and discrete variables are used as test-bed problems. The experimental results confirm the effectiveness of the proposed algorithm.

퍼지 게인 스케쥴링을 이용한 CSTR의 온도 제어 (Temperature Control of a CSTR using Fuzzy Gain Scheduling)

  • 김종화;고강영;진강규
    • 제어로봇시스템학회논문지
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    • 제19권9호
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    • pp.839-845
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    • 2013
  • A CSTR (Continuous Stirred Tank Reactor) is a highly nonlinear process with varying parameters during operation. Therefore, tuning of the controller and determining the transition policy of controller parameters are required to guarantee the best performance of the CSTR for overall operating regions. In this paper, a methodology employing the 2DOF (Two-Degree-of-Freedom) PID controller, the anti-windup technique and a fuzzy gain scheduler is presented for the temperature control of the CSTR. First, both a local model and an EA (Evolutionary Algorithm) are used to tune the optimal controller parameters at each operating region by minimizing the IAE (Integral of Absolute Error). Then, a set of controller parameters are expressed as functions of the gain scheduling variable. Those functions are implemented using a set of "if-then" fuzzy rules, which is of Sugeno's form. Simulation works for reference tracking, disturbance rejecting and noise rejecting performances show the feasibility of using the proposed method.

이온화식연기감지기의 사용기간에 따른 응답특성 연구 (A Study on the Response Characteristics Depending on Service Life of Ionization Smoke Detector)

  • 백원돈;김시국;옥경재;이춘하;지승욱
    • 한국화재소방학회논문지
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    • 제22권4호
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    • pp.61-64
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    • 2008
  • 본 논문은 이온화식연기감지기의 사용기간에 따른 응답특성 연구로서 소방대상물에 설치되어 환경의 영향을 받은 5년 이상된 이온화식연기감지기 360개를 시료로 사용하였다. 사용기간에 따른 이온화식연기감지기의 응답특성을 평가하기 위한 실험방법은 '감지기의 형식승인 및 검정기술기준(KOFEIS 0301)'에서 정한 기준에 따라 작동 및 부작동 실험을 실시하였다. 실험결과 사용기간이 오래될수록 이온화식연기감지기의 응답특성이 현저하게 저하되는 것을 확인할 수 있었다. 따라서 일정기간이 경과된 이온화식연기감지기는 조기화재감지를 위해 교체되는 것이 바람직할 것으로 사료된다.

발포제 종류에 따른 페놀 폼의 물성 연구 (Effect of Blowing Agents on Properties of Phenolic Foam)

  • 장서윤;김상범
    • 한국가스학회지
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    • 제20권2호
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    • pp.30-34
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    • 2016
  • 본 연구에서는 LNG나 LPG등과 같은 초저온용 단열재로 사용되는 폴리우레탄 폼을 대체하기 위한 연구의 일환으로 레졸형 페놀수지를 사용하여 페놀 폼을 합성하였다. 페놀 수지 발포 폼을 합성하기 위해 HCFC-141b, HFC-365mfc와 HFC-227fa의 혼합물, n-pentane, cyclopentane, n-hexane 및 cyclohexane을 발포제로 사용하여 발포제에 따른 페놀수지 폼의 물성변화를 고찰하였다. 발포제로 cyclohexane을 사용하였을때 가장 우수한 단열성능과 압축강도를 나타내었으며 동일한 발포제를 사용하여 합성한 폴리우레탄 폼과의 내열성을 비교한 결과 폴리우레탄 폼에 비해 매우 우수한 내열성을 나타내었다.

비용 최소화를 위한 플래어 시스템의 배관 서포트 타입 최적설계 (Optimal Determination of Pipe Support Types in Flare System for Minimizing Support Cost)

  • 박정민;박창현;김태수;최동훈
    • 대한조선학회논문집
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    • 제48권4호
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    • pp.325-329
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    • 2011
  • Floating, production, storage and offloading (FPSO) is a production facility that refines and saves the drilled crude oil from a drilling facility in the ocean. The flare system in the FPSO is a major part of the pressure relieving system for hydrocarbon processing plants. The flare system consists of a number of pipes and complicated connection systems. Decision of pipe support types is important since the load on the support and the stress in the pipe are influenced by the pipe support type. In this study, we optimally determined the pipe support types that minimized the support cost while satisfying the design constraints on maximum support load, maximum nozzle load and maximum pipe stress ratio. Performance indices included in the design constraints for a specified design were evaluated by pipe structural analysis using CAESAR II. Since pipe support types were all discrete design variables, an evolutionary algorithm (EA) was used as an optimizer. We successfully obtained the optimal solution that reduced the support cost by 27.2% compared to the initial support cost while all the design requirements were satisfied.