• 제목/요약/키워드: effective-medium model

검색결과 304건 처리시간 0.033초

초고온성 고세균 Thermococcus onnurineus의 개미산으로부터 바이오수소 생산을 위한 통계적 배지 최적화 (Statistical Optimization of Medium for Formate-driven Bio-hydrogen Production by the Hyperthermophilic Archaeon, Thermococus onnurineus)

  • 이성목;김태완;이현숙;이정현;강성균
    • Ocean and Polar Research
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    • 제39권4호
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    • pp.269-277
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    • 2017
  • Medium compositions for the hyperthermophilic archaeon, Thermococcus onnurineus NA1 was statistically optimized to enhance formate-driven hydrogen ($H_2$) production by using response surface methodology. From the Plackett-Burman design-based experiment, it was confirmed that among the minor components of medium such as KCl, $MgSO_4$, $NH_4Cl$, Cystein-HCl, trace elements, Fe-EDTA and $CaCl_2$, the trace elements were screened as the only positively effective components with respect to $H_2$ production. Subsequently, the optimal concentrations of the trace elements and the major components of a medium such as NaCl, yeast extract and sodium formate were determined from the five-level central composite design (CCD)-based experiment. The resulting quadratic model predicted the maximum $H_2$ production of 46.6 mmol/L in serum bottle and it was validated experimentally using the optimal medium initially supplemented with 26.70 g/L of NaCl, 9.81 g/L of sodium formate, 3.50 g/L of yeast extract and 4.59 mL/L of trace elements. From the duplicate batch cultivations in the fermentor using the optimized medium, the a maximum $H_2$ production rate up to 71.8 mmol/L/h could be obtained, which was a 65% enhanced value compared with that obtained using the control medium, showing the high efficiency of the optimized medium.

기포층 음향 삽입손실 연구: 기포커튼과 에어마스커 (Acoustic insertion loss by a bubble layer for the application to air bubble curtain and air masker)

  • 박철수;정소원;김건도;문일성;임근태
    • 한국음향학회지
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    • 제39권4호
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    • pp.227-236
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    • 2020
  • 해양구조물의 파일링 소음을 줄이기 위한 기포커튼과 선체 진동에 의한 수중방사소음 차단을 위한 에어마스커에 대하여 각각의 삽입손실 해석해를 유도하였다. 해석해를 구하기 위해 기포커튼과 에어마스커를 각각 '유체-기포층-유체' 그리고 '진공-평판-유체-기포층-유체'의 단순 모델로 가정하였고, 각 모델에서 해당 기포층을 복소수 형태의 파수와 임피던스로 규정된 유효매질로 치환하였다. 수치 모의를 통해 기포의 분포, 기포율, 그리고 기포층의 두께에 따른 삽입손실의 특성을 살펴보았다.

친환경농식품 가공업체의 경영계획 수립을 위한 다목표 수리계획모형의 적용 방안 (Applying Multi-objective Mathematical Programming Model for Business Planning of Eco-friendly Agrifood Processing Enterprise in Korea)

  • 조완형
    • 한국유기농업학회지
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    • 제26권2호
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    • pp.181-202
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    • 2018
  • Most of eco-friendly agrifood processing enterprises in Korean rural area are small and medium-sized business. For this reason, it's hard for eco-friendly agrifood processing enterprises to neither analyze business performance for efficient business management nor establish their own business plan for rational decision-making. Therefore it's necessary to design effective mathematical programming model and to make practical application which can support rational management decision-making ensuring the stable business activity of eco-friendly agrifood processing enterprises. Accordingly this paper focuses on the designing and its application of multi-objective mathematical programming model using goal programming to support rational decision-making of eco-friendly agrifood processing enterprise. Hansalimanseongmachum Food Inc. which runs soy bean processing business making tofu based on regional-based soybean farms around Anseong City will be the specific case to apply multi-objective mathematical programming model in practice. And it will suggest measures to support rational management decision-making of other eco-friendly agrifood processing enterprises.

Development of a simplified equivalent braced frame model for steel plate shear wall systems

  • Chatterjee, Arghya Kamal;Bhowmick, Anjan;Bagchi, Ashutosh
    • Steel and Composite Structures
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    • 제18권3호
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    • pp.711-737
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    • 2015
  • Steel Plate Shear Walls (SPSWs) have been accepted widely as an effective lateral load resisting system. For seismic performance evaluation of a multi-story building with SPSWs, detailed finite element models or a strip model can be used to represent the SPSW components. However, such models often require significant effort for tall or medium height buildings. In order to simplify the analysis process, discrete elements for the framing members can be used. This paper presents development of a simplified equivalent braced model to study the behavior of the SPSWs. The proposed model is expected to facilitate a simplification to the structural modeling of large buildings with SPSWs in order to evaluate the seismic performance using regular structural analysis tools. It is observed that the proposed model can capture the global behavior of the structures quite accurately and potentially aid in the performance-based seismic design of SPSW buildings.

CFD를 이용한 중형 경비정의 속도성능 평가 (A Study on the Speed Performance of a Medium Patrol Boat using CFD)

  • 박동우
    • 한국항해항만학회지
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    • 제38권6호
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    • pp.585-591
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    • 2014
  • 본 논문의 주 목적은 프루드 수가 0.5 이상인 중형 경비정의 속도성능을 모형시험 이전에 CFD 결과를 바탕으로 기존의 모형시험자료를 활용하였다. 모형시험 이전에 CFD를 이용하여 선속 별로 추정된 제동마력이 주어진 엔진마력을 만족하는지를 평가 하였다. 대상선박은 선미가 서로 다른 두 가지 선형을 선정하였다. 점성 유동장 계산은 상용 CFD 코드인 STAR-CCM+를 사용하였으며, 자유수면과 자세 변화(동적 트림)를 모두 고려하였다. 알몸 선체의 저항 값은 CFD를 이용하여 추정되었다. 점성 유동 해석을 통해 두 가지 선형의 자유수면 파형, 압력분포, 한계유선 그리고 프로펠러 면에서의 속도분포를 비교하였다. 점성 유동 해석 결과를 바탕으로 두 가지 선형에 대한 유효마력 즉, 저항성능을 평가하였다. 부가물 부착에 따른 저항 증가량과 준추진효율 계수(ETAD, ${\eta}_D$)는 모형시험 자료를 활용하였다. 중형 경비정과 같은 고속선박에 관한 속도성능 추정법이 CFD와 기존 시험자료를 이용하여 개발되었다.

매체 속성 평가에 따른 매체가치 비교 연구: 매체 광고 영향력 지수(MAIX: Media Advertising Impact Index) 개발을 중심으로 (A Study of Perception of Media Characteristics: Focused on Developing MAIX(Media Advertising Impact Index) model)

  • 이희준;조창환
    • 광고학연구
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    • 제27권3호
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    • pp.113-139
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    • 2016
  • 본 연구는 지금까지의 미디어 믹스 관련한 이론적 논의를 바탕으로 기존의 정량적 효용성이라는 하나의 잣대를 서로 상이한 매체에 일률적으로 적용하는 매체 전략이 아닌, 매체별가치 인식에 바탕을 둔 정성적 비교 평가에 의한 방안을 제시하였다. 이를 위해 학계 및 업계의 전문가를 대상으로 주요 광고 매체의 가치에 대한 설문조사를 실시했다. 구체적 분석의 대상이 된 매체는 TV, 라디오, 신문, 잡지, 인터넷, 모바일, 옥외매체, 디지털 사이니지였다. 본 연구의 결과, 첫째, 광고 매체가 지닌 영향력을 평가하는데 있어 가장 중요한 지표는 매체에 대한 몰입의 가능성, 수용자 도달률, 행동 타겟팅 가능성으로 조사됐다. 둘째, 인터넷은 매체별 속성 평가가 반영되어 합산된 매체 광고 영향력 지수(MAIX)에 의거할 때 가장 높은 평가를 받는 매체로 인식됐다. 셋째, 전문가들의 매체별 영향력 평가는 평가 지표별로 상이하였는데, 일례로 TV는 수용자 도달률과 몰입 가능성이 높은 매체인 반면에, 행동 타겟팅에 보다 적합한 매체는 모바일 및 인터넷이었다. 본 연구는 차별화된 매체 속성 인식에 대한 파악을 통해 매체별 경쟁력을 부여하는 미디어 믹스 전략을 수립하기 위한 이론적 근거를 제공했다는 데 의의가 있다.

전공 영어강의 만족도 및 학습효과 인식에 영향을 미치는 변인에 관한 연구 (Variables Affecting on Learners' Satisfaction and Effects of EMI)

  • 진성희;김학일
    • 공학교육연구
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    • 제16권3호
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    • pp.10-19
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    • 2013
  • Recently, Korean universities have increased the number of English Medium Instruction (EMI) lectures in order to allow students to gain both specialized knowledge and enhanced English ability. Previous researches on effective EMI lectures have focused on exploring the effects of learners' cognitive and affective characteristics on learning outcomes. Whereas the input variables of learning have been investigated as predicting variables of effects in EMI lectures, there has been a few research for investigating process variables to yield learning outcomes. The purpose of this study is to analyze the structural relationships among variables affecting on learner satisfaction and effects. The participants are 209 engineering students from various majors. Independent variables are defined as English motivation, English competency, and English confidence, a mediated variable is Cognitive engagement, and dependent variables are Learning satisfaction and Educational effect perception. The results show that the relationships are statistically significant: learners' English competency & English confidence ${\rightarrow}$ Cognitive engagement ${\rightarrow}$ Learning satisfaction ${\rightarrow}$ Educational effect perception. Especially, the structural model confirms that the effect of learners' English confidence on Learning satisfaction and Educational effect perception is mediated by the level of learners' Cognitive engagement. Further, the implication for effective EMI lectures is discussed based on the observed research results.

Failure mechanisms in coupled poro-plastic medium

  • Hadzalic, Emina;Ibrahimbegovic, Adnan;Nikolic, Mijo
    • Coupled systems mechanics
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    • 제7권1호
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    • pp.43-59
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    • 2018
  • The presence of the pore fluid strongly influences the reponse of the soil subjected to external loading and in many cases increases the risk of final failure. In this paper, we propose the use of a discrete beam lattice model with the aim to investigate the coupling effects of the solid and fluid phase on the response and failure mechanisms in the saturated soil. The discrete cohesive link lattice model used in this paper, is based on inelastic Timoshenko beam finite elements with enhanced kinematics in axial and transverse direction. The coupling equations for the soil-pore fluid interaction are derived from Terzaghi's principle of effective stresses, Biot's porous media theory and Darcy's law for fluid flow through porous media. The application of the model in soil mechanics is illustrated through several numerical simulations.

Analysis of transport properties of SLS polysilicon TFTs

  • Fortunato, G.;Bonfiglietti, A.;Valletta, A.;Mariucci, L.;Rapisarda, M.;Brotherton, S.D.
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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    • pp.513-518
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    • 2006
  • An investigation of the transport properties of polysilicon TFTs, using sequential laterally solidified, SLS, material, is presented. This material has a location controlled distribution of grain boundaries, GBs, which makes it particularly useful for the analysis of their influence on the performance of polysilicon TFTs, and to address the issue of the role of spatially localised trapping states. The experimental results were analyzed by using numerical simulations, and the effective medium approximation was compared with a discrete grain model.

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WDM 망에서의 다중 링 설계 알고리즘 연구 (Multi-ring Design Algorithm for Survivable WDM Networks)

  • 정지복
    • 경영과학
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    • 제26권3호
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    • pp.1-9
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    • 2009
  • In this paper, we present mathematical models for the ring covering problems arising in the design of multi-ring WDM networks. Also, we present efficient algorithms to solve the suggested models. By the computational experiment, our model can solve the medium-sized networks efficiently and shows better performance than the existing heuristic method. Although we propose an efficient method for the column generation procedure, branching rule that does not destroy the column generation structure is unsolved. Further research is required to develop an effective branching rule.