• 제목/요약/키워드: and system dynamics

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Comparisons of functional brain mappings in sensory and affective aspects following taste stimulation (미각자극에 따른 감각 및 감성적 미각정보 처리과정의 기능적 매핑 비교)

  • Lee, Kyung Hee
    • Science of Emotion and Sensibility
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    • v.15 no.4
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    • pp.585-592
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    • 2012
  • Food is crucial for the nutrition and survival of humans. Taste system is one of the fundamental senses. Taste cells detect and respond to five basic taste modalities (sweet, bitter, salty, sour, and umami). However, the cortical processing of taste sensation is much less understood. Recently, there were many efforts to observe the brain activation in response to taste stimulation using functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), and optical imaging. These different techniques do not provide directly comparable data each other, but the complementary investigations with those techniques allowed the description and understanding of the sequence of events with the dynamics of the spatiotemporal pattern of activation in the brain in response to taste stimulation. The purpose of this study is the understanding of the brain activities to taste stimuli in sensory and affective aspects and the reviewing of the recent research of the gustotopic map by functional brain mapping.

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Evaluation of wind loads and wind induced responses of a super-tall building by large eddy simulation

  • Lu, C.L.;Li, Q.S.;Huang, S.H.;Tuan, Alex Y.;Zhi, L.H.;Su, Sheng-chung
    • Wind and Structures
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    • v.23 no.4
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    • pp.313-350
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    • 2016
  • Taipei 101 Tower, which has 101 stories with height of 508 m, is located in Taipei where typhoons and earthquakes commonly occur. It is currently the second tallest building in the world. Therefore, the dynamic performance of the super-tall building under strong wind actions requires particular attentions. In this study, Large Eddy Simulation (LES) integrated with a new inflow turbulence generator and a new sub-grid scale (SGS) model was conducted to simulate the wind loads on the super-tall building. Three-dimensional finite element model of Taipei 101 Tower was established and used to evaluate the wind-induced responses of the high-rise structure based on the simulated wind forces. The numerical results were found to be consistent with those measured from a vibration monitoring system installed in the building. Furthermore, the equivalent static wind loads on the building, which were computed by the time-domain and frequency-domain analysis, respectively, were in satisfactory agreement with available wind tunnel testing results. It has been demonstrated through the validation studies that the numerical framework presented in this paper, including the recommended SGS model, the inflow turbulence generation technique and associated numerical treatments, is a useful tool for evaluation of the wind loads and wind-induced responses of tall buildings.

A Study on Forecasting Model based Weighted Moving Average for Cable TV Advertising Market (가중이동평균법을 이용한 케이블TV 광고시장에 대한 예측모형 개발)

  • Cho, Jae Hyung;Kim, Ho Young
    • The Journal of Information Systems
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    • v.25 no.2
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    • pp.153-171
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    • 2016
  • Purpose This study suggests the development of forecasting model for local cable TV advertisement. In order to verify the expected effect of the suggestion, using the causal loop map of System Dynamics, the factors affecting the prospects of cable TV commercial market were divided into 5 groups. Then targeting 97 people involved in the cable TV commercial market in Busan, Ulsan, and Gyeongnam, a survey was conducted on their perception of the current status of local advertisement market and future prospect. Design/methodology/approach The analysis of the collected data shows that workers in advertising and advertisers perceive the influence of cable TV as an advertising media to be high, while clearly understanding the problems of cable TV commercial market. Based on this the effects on the prospects of cable TV commercial market were analyzed and a forecasting method called Weighted Moving Average was applied. In order to improve accuracy of the added value of Weighted Moving Average, the 5 factors were divided into qualitative factors and quantitative factors, and using Multi-attribute Decision Making method, all the factors were normalized and weighting factors were deduced. The result of simulating the prospects of cable TV commercial market using Weighted Moving Average, both qualitative and quantitative factors showed downward turn in the market prospect for the following 10 years. Findings The result reflects generally negative perception of advertisement viewers about the prospects of cable TV commercial market. Compared to the previous studies on domestic cable TV commercials that focused on policy suggestions and surveys on perception of current status, this study has its significance in that it used scientific method and simulation for verification.

Layout optimization of wireless sensor networks for structural health monitoring

  • Jalsan, Khash-Erdene;Soman, Rohan N.;Flouri, Kallirroi;Kyriakides, Marios A.;Feltrin, Glauco;Onoufriou, Toula
    • Smart Structures and Systems
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    • v.14 no.1
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    • pp.39-54
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    • 2014
  • Node layout optimization of structural wireless systems is investigated as a means to prolong the network lifetime without, if possible, compromising information quality of the measurement data. The trade-off between these antagonistic objectives is studied within a multi-objective layout optimization framework. A Genetic Algorithm is adopted to obtain a set of Pareto-optimal solutions from which the end user can select the final layout. The information quality of the measurement data collected from a heterogeneous WSN is quantified from the placement quality indicators of strain and acceleration sensors. The network lifetime or equivalently the network energy consumption is estimated through WSN simulation that provides realistic results by capturing the dynamics of the wireless communication protocols. A layout optimization study of a monitoring system on the Great Belt Bridge is conducted to evaluate the proposed approach. The placement quality of strain gauges and accelerometers is obtained as a ratio of the Modal Clarity Index and Mode Shape Expansion values that are computed from a Finite Element model of the monitored bridge. To estimate the energy consumption of the WSN platform in a realistic scenario, we use a discrete-event simulator with stochastic communication models. Finally, we compare the optimization results with those obtained in a previous work where the network energy consumption is obtained via deterministic communication models.

Mathematical Modelling and Chaotic Behavior Analysis of Cyber Addiction (사이버 중독의 수학적 모델링과 비선형 거동 해석)

  • Kim, Myung-Mi;Bae, Young-Chul
    • Journal of the Korean Institute of Intelligent Systems
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    • v.24 no.3
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    • pp.245-250
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    • 2014
  • Addiction can be largely divided into two categories. One is called medium addiction in which medium itself causes an addiction. Another is called cause addiction that brings addiction through combination of sensitive self and latent personal action. The medium addiction involves addiction phenomena directly caused by illegal drugs, alcohol and various other chemicals. The cause addiction is dependent on personal sensitivities as a sensitive problem of personal and includes cyber addictions such as shopping, work, game, internet, TV, and gambling. In this paper we propose two-dimensional addiction model that are equivalent to using an R-L-C series circuit of Electrical circuit and a Spring-Damper-mass of mechanical system. We also organize a Duffing equation that is added a nonlinear term in the proposed two-dimensional addiction model. We represent periodic motion and chaotic motion as time series and phase portrait according to parameter's variation. We confirm that among parameters chaotic motion had addicted state and periodic motion caused by change in control coefficient had pre-addiction state.

Low-Load/Low-Eccentricity Performance Improvement Designs for Hydro Power Application of Cylindrical Turbine Guide Bearings - Introduction of Pad Leading-Edge Tapers (수력 원통형 터빈 가이드 베어링의 저부하/저편심 성능향상 설계 - 패드 선단 테이퍼의 도입)

  • Lee, An Sung;Jang, Sun-Yong
    • Tribology and Lubricants
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    • v.33 no.2
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    • pp.65-70
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    • 2017
  • In vertical hydro/hydraulic power turbine-generator applications, traditionally, cylindrical turbine guide bearings (TGBs) are widely used to provide turbine runner shafts with smooth rotation guides and supports. All existing cylindrical TGBs with simple plain pads have drawbacks such as having no pressure generation and film stiffness at the no-load condition and in addition, at the low-load/low-eccentricity condition, having very low film stiffness values and lacking design credibility in the stiffness values themselves. In this paper, in order to fundamentally improve the low-load/low-eccentricity performance of conventional cylindrical TGBs and thus enhance their design-application availability and usefulness, we propose to introduce a rotation-directional leading-edge taper to each partitioned pad, i.e., a pad leading-edge taper. We perform a design analysis of lubrication performance on $4-Pad{\times}4-Row$ cylindrical TGBs to verify an engineering/technical usefulness of the proposed pad leading-edge taper. Analysis results show that by introducing the leading-edge taper to each pad of the cylindrical TGB one can expect a constant high average direct stiffness with a high degree of design credibility, regardless of load value, even at the low-load/low-eccentricity condition and also control the average direct stiffness value by exploring the taper height as a design parameter. Therefore, we conclude that the proposed pad leading-edge tapers are greatly effective in more accurately predicting and controlling rotordynamic characteristics of vertical hydro-power turbine-generator rotor-bearing systems to which cylindrical TGBs are applied.

Analysis of Large-Amplitude Ship Motions Using a Cartesian-Gridbased Computational Method (직교격자 기반 수치기법을 이용한 선박의 대변위 운동해석)

  • Yang, Kyung-Kyu;Nam, Bo-Woo;Lee, Jae-Hoon;Kim, Yonghwan
    • Journal of the Society of Naval Architects of Korea
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    • v.49 no.6
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    • pp.461-468
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    • 2012
  • In this study, a Cartesian-grid method based on finite volume approach is applied to simulate the ship motions in large amplitude waves. Fractional step method is applied for pressure-velocity coupling and TVD limiter is used to interpolate the cell face value for the discretization of convective term. Water, air, and solid phases are identified by using the concept of volume-fraction function for each phase. In order to capture the interface between air and water, the tangent of hyperbola for interface capturing (THINC) scheme is used with weighed line interface calculation (WLIC) method which considers multidimensional information. The volume fraction of solid body embedded in the Cartesian grid system is calculated using a level-set based algorithm, and the body boundary condition is imposed by a volume weighted formula. Numerical simulations for the two-dimensional barge type model and Wigley hull in linear waves have been carried out to validate the newly developed code. To demonstrate the applicability for highly nonlinear wave-body interactions such as green water on the deck, numerical analysis on the large-amplitude motion of S175 containership is conducted and all computational results are compared with experimental data.

Numerical Study on the Effects of Combination of Blade Number for Shaft Forces and Moments of Contra-Rotating Propeller (상반회전 프로펠러의 날개수 조합에 따른 축기진력 연구)

  • Paik, Kwang-Jun;Lee, Jinsuk;Lee, Taegu;Hoshino, Tetsuji;Park, Hyung-Gil;Seo, Jongsoo
    • Journal of the Society of Naval Architects of Korea
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    • v.50 no.5
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    • pp.282-290
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    • 2013
  • The effects of the combination of blade number for forward and after propeller on the propeller shaft forces of a contra-rotating propeller (CRP) system are presented in the paper. The research is performed through the numerical simulations based on the Reynolds-Averaged Navier-Stokes equations (RANS). The simulation results of the present method in open water condition are validated comparing with the experimental data as well as the other numerical simulation results based on the potential method for 4-0-4 CRP (3686+3687A) and 4-0-5 CRP (3686+3849) of DTNSRDC. Two sets of CRP are designed and simulated to study the effect of the combination of blade number in behind-hull condition. One set consists of 3-blade and 4-blade, while the other is 4-blade and 4-blade. A full hull body submerged under the free surface is modeled in the computational domain to simulate directly the wake field of the ship at the propeller plane. From the simulation results, the fluctuations of axial force and moment are dominant in the case of same blade numbers for forward and after propellers, whereas the fluctuations of horizontal and vertical forces and moments are very large in the case of different blade numbers.

A Study on the Valuation of a Supply Chain Considering Management Efficiency and Environmental Effect (운영 효율성과 환경 영향을 고려한 공급사슬 평가에 관한 연구)

  • Kim, Ji-Yeon;Kim, Hae-Joong;Shin, Ki-Tae;Park, Jin-Woo
    • Journal of the Korea Society for Simulation
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    • v.16 no.3
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    • pp.29-38
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    • 2007
  • Recently, the deepening of the environment and accompanying concerns produce various environmental regulations. For example, EPR(Extended Producer Responsibility) is emphasized in many countries such as USA and Europe. According to this, the construction of a reverse supply chain is under compulsion. A diversity of parts can be controlled by a government or enterprises in the construction and management of a reverse supply chain and the effect to the environment is changed according to the policy. Therefore, it is essential to understand the effects of regulations or policies of a government and enterprises on a supply chain. The object of this research is to develop a means to assess the management efficiency and the environmental effect over a whole supply chain and show the effects of various reverse supply chain construction policies on a supply chain. This model can be utilized to establish appropriate policies by understanding the change in the management efficiency and the environmental effect according to the reverse supply chain construction and management method.

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A CFD Analysis on Heat Transfer of High Temperature Steam through Interface with Superheater and SOEC for Hydrogen Production (SOEC에 과열기의 고온 스팀을 공급하는 Interface의 열전달에 관한 전산해석)

  • BYUN, HYUN SEUNG;HAN, DANBEE;PARK, SEONGRYONG;CHO, CHONGPYO;BAEK, YOUNGSOON
    • Journal of Hydrogen and New Energy
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    • v.31 no.2
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    • pp.169-176
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    • 2020
  • There is a growing interest in hydrogen energy utilization since an alternative energy development has been demanded due to the depletion of fossil fuels. Hydrogen is produced by the reforming reaction of natural gas and biogas, and the electrolysis of water. An solid oxide electrolyte cell (SOEC) is reversible system that generates hydrogen by electrolyzing the superheated steam or producing the electricity from a fuel cell by hydrogen. If the water can be converted into steam by waste heat from other processes it is more efficient for high-temperature electrolysis to convert steam directly. The reasons are based upon the more favorable thermodynamic and electrochemical kinetic conditions for the reaction. In the present study, steam at over 180℃ and 3.4 bars generated from a boiler were converted into superheated steam at over 700℃ and 3 bars using a cylindrical steam superheater as well as the waste heat of the exhaust gas at 900℃ from a solid refuse fuel combustor. Superheated steam at over 700℃ was then supplied to a high-temperature SOEC to increase the hydrogen production efficiency of water electrolysis. Computational fluid dynamics (CFD) analysis was conducted on the effects of the number of 90° elbow connector for piping, insulation types and insulation layers of pipe on the exit temperature using a commercial Fluent simulator. For two pre-heater injection method of steam inlet and ceramic wool insulation of 100 mm thickness, the highest inlet temperature of SOEC was 744℃ at 5.9 bar.