• Title, Summary, Keyword: equilibrium process

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Chemical Equilibrium Modeling for Magnetite-Packed Crevice Chemistry in a Nuclear Steam Generator

  • Bahn, Chi-Bum;Rhee, In-Hyoung;Hwang, Il-Soon;Park, Byung-Gi
    • Bulletin of the Korean Chemical Society
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    • v.26 no.11
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    • pp.1783-1789
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    • 2005
  • Modeling of a steam generator crevice in a nuclear power system needs to take into account both thermalhydraulic and chemical phenomena. As a first step towards developing a reliable model, a chemical equilibrium model was developed to predict chemical speciation in a magnetite-packed crevice by adopting the “tableau” method. The model was benchmarked with the available experimental data and the maximum deviation did not exceed two orders of magnitude. The developed model was applied to predict the chemical speciation in a magnetite-packed crevice. It was predicted that caustic environment was developed by the concentration of NaOH and the dissolution of magnetite. The model indicated that the dominant aqueous species of iron in the caustic crevice was $FeO_2\;^-$. The increase of electrochemical corrosion potential observed in the experiment was rationalized by the decrease of dissolved hydrogen concentration due to a boiling process. It was predicted that under the deaerated condition magnetite was oxidized to hematite.

Development of limit equilibrium method as optimization in slope stability analysis

  • Mendjel, D.;Messast, S.
    • Structural Engineering and Mechanics
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    • v.41 no.3
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    • pp.339-348
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    • 2012
  • The slope stability analysis is usually done using the methods of calculation to rupture. The problem lies in determining the critical failure surface and the corresponding factor of safety (FOS). To evaluate the slope stability by a method of limit equilibrium, there are linear and nonlinear methods. The linear methods are direct methods of calculation of FOS but nonlinear methods require an iterative process. The nonlinear simplified Bishop method's is popular because it can quickly calculate FOS for different slopes. This paper concerns the use of inverse analysis by genetic algorithm (GA) to find out the factor of safety for the slopes using the Bishop simplified method. The analysis is formulated to solve the nonlinear equilibrium equation and find the critical failure surface and the corresponding safety factor. The results obtained by this approach compared with those available in literature illustrate the effectiveness of this inverse method.

Condensation processes in transonic two-phase flows of saturated humid air using a small-disturbance model (미교란 모델을 이용한 포화 습공기 천음속 2상 유동에서의 응축현상)

  • Lee, Jang-Chang;Zvi Rusak
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.6
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    • pp.23-29
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    • 2003
  • Transonic two-phase flow of Saturated humid air, in which relative humidity is 100%, with various condensation processes around thin airfoils is investigated. The study uses an extended transonic small-disturbance(TSD) model of Rusak and Lee [11, 12] which includes effects of heat addition to the flow due to condensation. Two possible limit types of condensation processes are considered. In the nonequilibrium and homogeneous process, the condensate mass fraction is calculated according to classical nucleation and droplet growth rate models. In the equilibrium process, the condensate mass fraction is calculated by assuming an isentropic process. The flow and condensation equations are solved numerical1y by iterative computations. Results under same upstream conditions describe the flow structure, field of condensate, and pressure distribution on airfoil's surfaces. It is found that flow characteristics, such as position and strength of shock waves and airfoil’s pressure distribution, are different for the two condensation processes. Yet, in each case, heat addition as a result of condensation causes significant changes in flow behavior and affects the aerodynamic performance of airfoils.

Thermodynamic analysis of the deposition process of SiC/C functionally gradient materials by CVD technique (CVD법을 이용한 SiC/C경사기능재료 증착공정의 열역학적 해석)

  • 박진호;이준호;신희섭;김유택
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.12 no.2
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    • pp.101-109
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    • 2002
  • A complex chemical equilibrium analysis was performed to study the hot-wall CVD process of the SiC/C functionally gradient materials (FGM). Thermochemical calculations of the Si-C-H-Cl system were carried out, and the effects of process variables(deposition temperature, reactor pressure, C/[Si+C] and H/[Si+C] ratios in the source gas) on the composition of deposited layers and the deposition yield were investigated. The CVD phase diagrams of the SiC/C FGM deposition were obtained, and the optimum process windows were estimated from the results.

A Proposal for a Seismic Design Process for a Passive Control Structural System Based on the Energy Equilibrium Equation

  • Oh, Sang-Hoon;Shin, Seung-Hoon
    • International journal of steel structures
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    • v.17 no.4
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    • pp.1285-1316
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    • 2017
  • A systematic design method for actualizing a passive control structure that can effectively exert its capabilities to minimize damage from an earthquake has yet to be presented. In particular, a clear method for placing EDDs that can improve seismic capability under earthquake delivery has yet to be presented, causing the dependence on the design of placing the damper after repetitive response analysis and trial and error work directly. However, in order to obtain seismic capability that the designer intends, the designer needs to be able to predict optimum placement of the damper prior to response analysis and determine the design result to be reliable. This study aims to suggest a design process of passive control structure, which includes design and placement of the damper for obtaining the seismic capability of the passive control structure as intended by the designer. Also, dynamic response analysis was conducted on structures designed using the design process suggested in this study to confirm whether the seismic capability intended by the design has been achieved, verifying the validity of the design process.

A Study on the Equilibrium Theory of Business Administration Organization (경영조직의 균형이론에 관한 연구 -"바아나이드" 및 "마취-사이몬"의 이론을 중심으로-)

  • 이경희
    • The Journal of Fisheries Business Administration
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    • v.9 no.1
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    • pp.29-46
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    • 1978
  • The Equilibrium Theory is one of the key theories on the study of maintenance and continuance of organization. A contributor or participant of the business organization has been given the needed incucements and motivated to join in business. To keep this situation balanced is, so-called, the organization equilibrium. C. I. Barnard was the first to research this, and that J. G. March and H. A. Simon advanced it. Modern organization theory is not only the equilibrium theory but continuance theory of organization. That is, the continuance of business administration organization relies on the willingness to cooperate with which the participants in business try to devote themselves to business. The organization itself is not only combined with its members and assets but a kind of behaviour system which every member makes an effort to contribute. On a view of dynamics, organization remains, prospers and deceases in process of its formation, disorganization and reformation. But taking consideration into going concern, it is necessary that we should plan to strike a balance of business administration organization. We can write down the proposition of this theory as follows: The continuance and growth of organization=inducements contribution The basic idea of this theory was established by C. I. Barnard. But it implied many problems such as incorrect statistical measures and the defects of objectivity. These problems were more or less rearranged and improved by so-called March-Simon's equilibrium theory. Especially March-Simon's general models of organization equilibrium are a great success in this field. In the future, these problems mentioned above will be a challenge to workers in this field how we shall diminish the defects to the minimum and how perfectly we can progress it.

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Chemical Reacting Flow Analysis of the 30 tonf - class KARl LRE Nozzle (KARI 30톤급 액체로켓엔진 노즐 유동 화학 반응 해석)

  • Lee, Dae-Sung;Kang, Ki-Ha;Cho, Duck-Rae;Choi, J.Y.;Choi, H.S.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.105-109
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    • 2007
  • Three methods of nozzle flow analysis, frozen-equilibrium, shifting-equilibrium and non-equilibrium approaches, were used to rocket nozzle flow, those were coupled with the methods of computational fluid dynamics code. For a design of high temperature rocket nozzle, chemical equilibrium analysis which shares the same numerical characteristics with frozen flow analysis can be an efficient design tool for predicting maximum thermodynamic performance of the nozzle. In this study, shifting-equilibrium flow analysis was carried out for the 30 $ton_f$-class KARl liquid rocket engine nozzle together with frozen flow. The performance evaluation based on the 30 $ton_f$-class KARl LRE nozzle flow analyses will provide an understanding of the thermochemical process in the nozzle and performances of nozzle.

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Numerical Study of Chemical Reaction for Liquid Rocket Propellant Using Equilibrium Constant (평형상수를 이용한 액체로켓 추진제의 화학반응 수치연구)

  • Jang, Yo Han;Lee, Kyun Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.4
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    • pp.333-342
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    • 2016
  • Liquid rocket propulsion is a system that produces required thrust for satellites and space launch vehicles by using chemical reactions of a liquid fuel and a liquid oxidizer. Monomethylhydrazine/dinitrogen tetroxide, liquid hydrogen/liquid oxygen and RP-1/liquid oxygen are typical combinations of liquid propellants commonly used for the liquid rocket propulsion system. The objective of the present study is to investigate useful design and performance data of liquid rocket engine by conducting a numerical analysis of thermochemical reactions of liquid rocket propellants. For this, final products and chemical compositions of three liquid propellant combinations are calculated using equilibrium constants of major elementary equilibrium reactions when reactants remain in chemical equilibrium state after combustion process. In addition, flame temperature and specific impulse are estimated.

Network Attack and Defense Game Theory Based on Bayes-Nash Equilibrium

  • Liu, Liang;Huang, Cheng;Fang, Yong;Wang, Zhenxue
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.10
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    • pp.5260-5275
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    • 2019
  • In the process of constructing the traditional offensive and defensive game theory model, these are some shortages for considering the dynamic change of security risk problem. By analysing the critical indicators of the incomplete information game theory model, incomplete information attack and defense game theory model and the mathematical engineering method for solving Bayes-Nash equilibrium, the risk-averse income function for information assets is summarized as the problem of maximising the return of the equilibrium point. To obtain the functional relationship between the optimal strategy combination of the offense and defense and the information asset security probability and risk probability. At the same time, the offensive and defensive examples are used to visually analyse and demonstrate the incomplete information game and the Harsanyi conversion method. First, the incomplete information game and the Harsanyi conversion problem is discussed through the attack and defense examples and using the game tree. Then the strategy expression of incomplete information static game and the engineering mathematics method of Bayes-Nash equilibrium are given. After that, it focuses on the offensive and defensive game problem of unsafe information network based on risk aversion. The problem of attack and defense is obtained by the issue of maximizing utility, and then the Bayes-Nash equilibrium of offense and defense game is carried out around the security risk of assets. Finally, the application model in network security penetration and defense is analyzed by designing a simulation example of attack and defense penetration. The analysis results show that the constructed income function model is feasible and practical.

Equilibrium and kinetic studies of an electro-assisted lithium recovery system using lithium manganese oxide adsorbent material

  • Lee, Dong-Hee;Ryu, Taegong;Shin, Junho;Kim, Young Ho
    • Carbon letters
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    • v.28
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    • pp.87-95
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    • 2018
  • This study examined the influence of operating parameters on the electrosorptive recovery system of lithium ions from aqueous solutions using a spinel-type lithium manganese oxide adsorbent electrode and investigated the electrosorption kinetics and isotherms. The results revealed that the electrosorption data of lithium ions from the lithium containing aqueous solution were well-fitted to the Langmuir isotherm at electrical potentials lower than -0.4 V and to the Freundlich isotherm at electrical potentials higher than -0.4 V. This result may due to the formation of a thicker electrical double layer on the surface of the electrode at higher electrical potentials. The results showed that the electrosorption reached equilibrium within 200 min under an electrical potential of -1.0 V, and the pseudo-second-order kinetic model was correlated with the experimental data. Moreover, the adsorption of lithium ions was dependent on pH and temperature, and the results indicate that higher pH values and lower temperatures are more suitable for the electrosorptive adsorption of lithium ions from aqueous solutions. Thermodynamic results showed that the calculated activation energy of $22.61kJ\;mol^{-1}$ during the electrosorption of lithium ions onto the adsorbent electrode was primarily controlled by a physical adsorption process. The recovery of adsorbed lithium ions from the adsorbent electrode reached the desorption equilibrium within 200 min under reverse electrical potential of 3.5 V.