• Title/Summary/Keyword: co-simulation

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[ $CO_2$ ] Recovery from LNG-fired Flue Gas Using a Multi-staged Pilot-scale Membrane Plant (파일럿규모의 다단계 막분리 공정을 통한 LNG 연소 배가스로부터 이산화탄소의 회수연구)

  • Kim, Jeong-Hoon;Choi, Seung-Hak;Kim, Beom-Sik;Lee, Soo-Bok;Lee, Yong-Taek
    • Membrane Journal
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    • v.17 no.3
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    • pp.197-209
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    • 2007
  • In this study, a multi-staged pilot-scale membrane plant was constructed and operated for the separation of $CO_2$ from LNG-fired boiler flue gas of 1,000 $Nm^3/day$. The target purity and recovery ratio of $CO_2$ required for the pilot plant were 99% and 90%, respectively. For this purpose, we previously developed the asymmetric polyethersulfone hollow fibers and evaluated the effects of operating pressure and feed concentration of $CO_2$ on separation performance[1,2]. The permeation data obtained were also analyzed in relation with the numerical simulation data using counter-current flow model[3,4]. Based on these results, we designed and prepared the demonstration plant consisting of dehumidification process and four-staged membrane process. The operation results using this plant were compared with the numerical simulation results on multi-staged membrane process. The experimental results matched well with the numerical simulation data. The concentration and the recovery ratio of $CO_2$ in the final stage permeate stream were ranged from $95{\sim}99%$ and $70{\sim}95%$, respectively, depending on the operating conditions. This study demonstrated the applicability of the membrane-based pilot plant for $CO_2$ recovery from flue gas.

Absorbtion Spectroscopy, Molecular Dynamics Calculations, and Multivariate Curve Resolution on the Phthalocyanine Aggregation

  • Ajloo, Davood;Ghadamgahi, Maryam;Shaheri, Freshte;Zarei, Kobra
    • Bulletin of the Korean Chemical Society
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    • v.35 no.5
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    • pp.1440-1448
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    • 2014
  • Co(II)-tetrasulfonated phthalocyanine (CoTSP) is known to be aggregated to dimer at high concentration levels in water. A study on the aggregation of CoTSP using multivariate curve resolution analysis of the visible absorbance spectra over a concentration range of 30, 40 and 50 ${\mu}M$ in the presence of dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), acetonitrile (AN) and ethanol (EtOH) in the concentration range of 0 to 3.57 M is conducted. A hard modeling-based multivariate curve resolution method was applied to determine the dissociation constants of the CoTSP aggregates at various temperatures ranging from 25, 45 and $65^{\circ}C$ and in the presence of various co-solvents. Dissociation constant for aggregation was increased and then decrease by temperature and concentration of phthalocyanine, respectively. Utilizing the vant Hoff relation, the enthalpy and entropy of the dissociation equilibriums were calculated. For the dissociation of both aggregates, the enthalpy and entropy changes were positive and negative, respectively. Molecular dynamics simulation of cosolvent effect on CoTSP aggregation was done to confirm spectroscopy results. Results of radial distribution function (RDF), root mean square deviation (RMSD) and distance curves confirmed more effect of polar solvent to decrease monomer formation.

Effect of octadecylamine concentration on adsorption on carbon steel surface

  • Liu, Canshuai;Lin, Genxian;Sun, Yun;Lu, Jundong;Fang, Jun;Yu, Chun;Chi, Lisheng;Sun, Ke
    • Nuclear Engineering and Technology
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    • v.52 no.10
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    • pp.2394-2401
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    • 2020
  • Octadecylamine is an effective film-forming amine that protects carbon steel from corrosion. In the present study, the effect of octadecylamine concentration on adsorption on a carbon steel surface was investigated in anaerobic alkaline solution by using SEM/EDS, TEM and the Materials Studio simulation techniques. TEM morphology observation and EDS elemental detection determine the thicknesses of octadecylamine film on a carbon steel surface, which are confirmed by the in-situ electrochemical impedance spectroscopy measurement and resistance calculation. The Materials Studio simulation reveals the number of octadecylamine film layers at different concentrations. Results obtained in this study indicate that adsorption of octadecylamine film on carbon steel proceeds with the multi-layer adsorption mechanism.

EMI Prediction of Slew-Rate Controlled I/O Buffers by Full-Wave and Circuit Co-Simulation

  • Kim, Namkyoung;Hwang, Jisoo;Kim, SoYoung
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.14 no.4
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    • pp.471-477
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    • 2014
  • In this paper, a modeling and co-simulation methodology is proposed to predict the radiated electromagnetic interference (EMI) from on-chip switching I/O buffers. The output waveforms of I/O buffers are simulated including the on-chip I/O buffer circuit and the RC extracted on-chip interconnect netlist, package, and printed circuit board (PCB). In order to accurately estimate the EMI, a full-wave 3D simulation is performed including the measurement environment. The simulation results are compared with near-field electromagnetic scan results and far-field measurements from an anechoic chamber, and the sources of emission peaks were analyzed. For accurate far-field EMI simulation, PCB power trace models considering IC switching current paths and external power cable models must be considered for accurate EMI prediction. With the proposed EMI simulation model and flow, the electromagnetic compatibility can be tested even before the IC is fabricated.

Monte Carlo Simulation of MR Damper Landing Gear Taxiing Mode under Nonstationary Random Excitation

  • Lee, Hyo-Sang;Jang, Dae-Sung;Hwang, Jai-Hyuk
    • Journal of Aerospace System Engineering
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    • v.14 no.4
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    • pp.10-17
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    • 2020
  • When an aircraft is taxiing, excitation force is applied according to the shape of the road surface. The sprung mass acceleration caused by the excitation of the road surface negatively affects the feeling of boarding. This paper addresses the verification process of the semi-active control method applied to improve the feeling of boarding. The Magneto-Rheological damper landing gear model is employed alongside the control method. It is a Oleo-Pneumatic damper filled with a fluid having the characteristics of increasing yield stress when subjected to a magnetic field. The control method involves verifying Skyhook Control Type2 developed by Skyhook control. The Sinozuka white noise model that considers runway characteristics was employed for the road surface in the simulation. The runway road surface obtained through this model has stochastic characteristics, so the dynamic characteristics were analyzed by applying Monte-Carlo simulation. A dynamic analysis was conducted by co-simulating the landing gear model made by RecurDyn and the control method designed by Simulink. Simulation results show that the Skyhook Control Type2 method has the best control effect in the low speed range compared to the passive type (without control) and skyhook control.

Impact of MJS treatment and artificial freezing on ground temperature variation: A case study

  • Jiling, Zhao;Ping, Yang;Lin, Li;Junqing, Feng;Zipeng, Zhou
    • Geomechanics and Engineering
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    • v.32 no.3
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    • pp.293-305
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    • 2023
  • To ensure the safety of underground infrastructures, ground can sometimes be first treated by cement slurry and then stabilized using artificial ground freezing (AGF) technique before excavation. The hydration heat produced by cement slurry increases the soil temperature before freezing and results in an extension of the active freezing time (AFT), especially when the Metro Jet System (MJS) treatment is adopted due to a high cement-soil ratio. In this paper, by taking advantage of an on-going project, a case study was performed to evaluate the influence of MJS and AGF on the ground temperature variation through on-site measurement and numerical simulation. Both on-site measurement and simulation results reveal that MJS resulted in a significant increase in the soil temperature after treatment. The ground temperature gradually decreases and then stabilized after completion of MJS. The initiation of AGF resulted in a quick decrease in ground temperature. The ground temperature then slowly decreased and stabilized at later freezing. A slight difference in ground temperature exists between the on-site measurements and simulation results due to limitations of numerical simulation. For the AGF system, numerical simulation is still strongly recommended because it is proven to be cost-effective for predicting the ground temperature variation with reasonable accuracy.

Reflective Twist Nematic Liquid Crystal Display For High Reflectance.

  • Son, Ock-Soo;Park, Young-Il;Beak, Do-Hyoen;Son, Gon;Suh, Dong-Hea
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.292-294
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    • 2008
  • We have developed new reflective LCD for Mixed twist nematic LC mode with high quality image. We have found out an optimal twist angle of LC and optical film's axis by simulation. Also we measured electro-optic characteristics for new design panel. As a result, high reflectance and wide viewing angle characteristics were achieved.

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An Analysis of Hydrologic Changes in Daechung Dam Basin using GCM Simulation Results due to Global Warming (GCM 결과를 이용한 지구온난화에 따른 대청댐 유역의 수문환경 분석)

  • An, Jae-Hyeon;Yu, Cheol-Sang;Yun, Yong-Nam
    • Journal of Korea Water Resources Association
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    • v.34 no.4
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    • pp.335-345
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    • 2001
  • The objective of this research is to analyze the hydrological environment changes in Daechung Dam Basin due to the global warming. GCM simulation results are used to predict the possible changes in precipitation and temperature. The changes of potential evapotranspiration, soil moisture and runoff due to the changes of precipitation and temperature are analyzed using a conceptual water balance model. From the simulation results using the water balance model for lx$CO_2$ and 2x$CO_2$ situations, it has been found that the runoff would decrease in Winter, but increase in Summer and Fall due to the global warming. Therefore, it is predicted that the frequency of drought and flood occurrences in Daechung Dam Basin would be increased in 2x$CO_2$ condition.

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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.

Decision-Making System of UAV for ISR Mission Level Autonomy (감시정찰 임무 자율화를 위한 무인기의 의사결정 시스템)

  • Uhm, Taewon;Lee, Jang-Woo;Kim, Gyeong-Tae;Yang, Seung-Gu;Kim, Joo-Young;Kim, Jae-Kyung;Kim, Seungkeun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.10
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    • pp.829-839
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    • 2021
  • Autonomous system for UAVs has a capability to decide an appropriate current action to achieve the goal based on the ultimate mission goal, context of mission, and the current state of the UAV. We propose a decision-making system that has an ability to operate ISR mission autonomously under the realistic limitation such as low altitude operation with high risk of terrain collision, a set of way points without change of visit sequence not allowed, and position uncertainties of the objects for the mission. The proposed decision-making system is loaded to a Hardware-In-the-loop Simulation environment, then tested and verified using three representative scenarios with a realistic mission environment. The flight trajectories of the UAV and selected actions via the proposed decision-making system are presented as the simulation results with discussion.