• Title/Summary/Keyword: Power-Law Model

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COLOR GRADIENTS WITHIN GLOBULAR CLUSTERS: RESTRICED NUMERICAL SIMULATION

  • Sohn, Young-Jong;Chun, Mun-Suk
    • Journal of Astronomy and Space Sciences
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    • v.14 no.1
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    • pp.1-17
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    • 1997
  • The results of a restricted numerical simulation for the color gradients within globular clusters have been presented. The standard luminosity function of M3 and Salperter's initial mass functions were used to generate model clusters as a fundamental population. Color gradients with the sample clusters for both King and power law cusp models of surface brightness distributions are discussed in the case of using the standard luminosity function. The dependence of color gradients on several parameters for the simulations with Salpter's initial mass functions, such as slope of initial mass functions, cluster ages, metallicities, concentration parameters of King model, and slopes of power law, are also discussed. No significant radial color gradients are shown to the sample clusters which are regenerated by a random number generation technique with various parameters in both of King and power law cusp models of surface brightness distributions. Dynamical mass segregation and stellar evolution of horizontal branch stars and blue stragglers should be included for the general case of model simulations to show the observed radial color gradients within globular clusters.

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Direct Energy Method of Power System Stability Analysis and its Application by using Energy Conservation Law (에너지보존법칙을 이용한 전력계통 안정도 직접 해석법에서의 응용)

  • Lee, Yong-Hoon;Cho, Byoung-Hoon;Ryu, Heon-Su;Moon, Young-Hyun
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.10
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    • pp.1207-1214
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    • 1999
  • Many papers have recently been presented to develop energy functions for power systems. However, earlier studies adopted case-by-case approaches, which failed to give a general approach to deal with various kinds of generator models. In this paper, two useful theorems are developed regarding the integral relationships of the generator power versus its phasor current and voltage. By using the proposed theorems, an exact energy conservation law can be derived from the complex integral. The proposed energy conservation law, which is free of the generator model, can be utilized to develop energy functions for various kinds of generator models including the speed governors and exciters. An illustrative example is given for a multimachine system with the Eq' model of generator. This thesis also shows a possibility of more accurate and fast stability analysis by using the proposed Energy Conservation Law.

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Energy Conservation Law and its application for Direct Energy method of Power System Stability (에너지 보존법칙과 전력계통 안정도 직접 해석법에서의 응용)

  • Moon, Young-Hyun;Lee, Yong-Hoon;Cho, Byoung-Hoon;Ryu, Heon-Su;Choi, Byoung-Kon
    • Proceedings of the KIEE Conference
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    • 1998.11a
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    • pp.263-268
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    • 1998
  • Many papers have recently been presented to develop energy functions for power systems. However, earlier studies adopted case-by-case approaches, which failed to give a general approach to deal with various kinds of generator models. In this paper, two useful theorems are developed regarding the integral relationships of the generator power versus its phasor current and voltage. By using the proposed theorems, an exact energy conservation law can be derived from the complex integral. The proposed energy conservation law, which is free of the generator model, can be utilized to develop energy functions for various kinds of generator models including the speed governors, and exciters. An illustrative example is given for a multimachine system with the Eq' model of generator. This thesis also shows a possibility of more accurate and fast stability analysis by using the proposed Energy Conservation Law.

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Reactor Sizing for Hydrogen Production from Ethane over Ni Catalyst (니켈 촉매 상에서 에탄으로부터 수소생산을 위한 반응기 사이징)

  • Seong, Minjun;Lee, Kyungeun;Cho, Jung-Ho;Lee, Young-Chul;Jeon, Jong-Ki
    • Clean Technology
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    • v.19 no.1
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    • pp.51-58
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    • 2013
  • In this study, kinetics data was obtained for steam reforming reaction of ethane over the nickel catalyst. The variables of steam reforming reaction were reaction temperature, partial pressure of ethane, and mole ratio of steam and ethane. Parameters for the power rate law kinetic model and the Langmuir-Hinshelwood model were obtained from the kinetic data. Also, sizing of steam reforming reactor was performed by using PRO/II simulator. For the steam reforming reaction of ethane, Langmuir-Hinshelwood model determining the reaction rate by the surface reaction was better suited than a simple power rate law kinetic model. On water-gas-shift reaction, power rate law kinetic model was well fitted to the kinetic data. Reactor size can be calculated for production of hydrogen through PRO/II simulation.

The Powers and Interim Measures of the Arbitral Tribunal in International Commercial Arbitration (국제상사중재에서 중재판정부의 권한과 임시적 처분에 관한 연구)

  • Lee, Kang-Bin
    • Journal of Arbitration Studies
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    • v.18 no.2
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    • pp.103-127
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    • 2008
  • This paper is to research the powers and interim measures of the arbitral tribunal in the arbitral proceedings of the international commercial arbitration under arbitration legislation and arbitration rules including the UNCITRAL Model Law and Arbitration Rules. The powers of the arbitral tribunal may be found within the arbitration agreement or any arbitration rules chosen by the parties, or the chosen procedural law. The power of the arbitral tribunal to decide its own jurisdiction is one of the fundamental principles of international commercial arbitration. It is a power which is now found in nearly all modern arbitration and rules of arbitration. Where an arbitral tribunal has been appointed then it will usually have the power to proceed with the arbitration in the event that a party fails to appear. It cannot force a party to attend but it may sanction the failure. While the arbitral tribunal can direct the parties to attend and give evidence the arbitral tribunal has no power to compel a party to give evidence. The arbitral tribunal may continue the arbitration in the absence of the party or its failure to submit evidence and make an award on the evidence before it. Under most of arbitration legislation and arbitration rules, the arbitral tribunal has the power to appoint experts and obtain expert evidence. The power to order a party to disclose documents in its possession is a power given to the arbitral tribunal by many national laws and by most arbitration rules. The arbitral tribunal cannot, however, compel disclosure and in the case where a party refuses to disclosure documents then the sanctions that the arbitral tribunal can impose must be ascertained from the applicable rules or the relevant procedural law. A number of arbitration rules and national laws allow for the arbitral tribunal to correct errors within the award. Most of arbitration legislation and arbitration rules permit the arbitral tribunal to grant orders for interim measure of protection. Article 17(1) of the Revised UNCITRAL Model Law of 2006 states: Unless otherwise agreed by the parties, the arbitral tribunal may, at the request of a party, grant interim measures. Interim measures of protection usually take such forms as (1) conservatory measures intended to prevent irreparable damage and maintain the status quo; (2) conservatory measures intended to preserve evidence or assets. Orders for interim measures by the arbitral tribunal are not self-enforcing. However, the arbitral tribunal must have the powers necessary to make interim measures effective. The Article 17 B of the Revised UNCITRAL Model Law of 2006 provides applications for preliminary orders and conditions for granting preliminary orders. And the Article 17 H provides recognition of enforcement of interim measures. In conclusion, the revised articles with regard to interim measures of the UNCITRAL Model Law of 2006 would contribute significantly to the security of the effectiveness of interim measures in international commercial arbitration. Therefore, Korean Arbitration Law and Arbitration Rules would be desirable to admit such revised articles with regard interim measures.

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Effects of Geometry and Operating Fluid on the Expansion Behavior of Liquid-Solid Fluidized Beds

  • Mohsen Mozafari-Shamsi;Alireza Malooze;Mohammad Sefid;Mostafa Soroor;Ehsan Mehrabi Gohari
    • Korean Chemical Engineering Research
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    • v.61 no.2
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    • pp.312-321
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    • 2023
  • Fluidized beds have been widely used in industrial applications, which in most of them, the operating fluid is non-Newtonian. In this study, the combination of the lattice Boltzmann method (LBM) and the smoothed profile method has been developed for non-Newtonian power-law fluids. The validation of the obtained model were investigated by experimental correlations. This model has been used for numerical studying of changing the operating fluid and geometrical parameters on the expansion behavior in liquid-solid beds with both Newtonian and non-Newtonian fluids. Investigations were performed for seven different geometries, one Newtonian, and two non-Newtonian fluids. The power-law index was in the range of 0.8 to 1, and the results for the Newtonian fluidized beds show more porosity than the non-Newtonian ones. Furthermore, increasing the power-law index resulted in enhancing the bed porosity. On the other hand, bed porosity was decreased by increasing the initial bed height and the density of the solid particles. Finally, the porosity ratio in the bed was decreased by increasing the solid particle diameter.

Constitutive Models for Final Stage Densification of Powder Compacts with Power-Law Creep Deformation (Power-law 크리프 변형을 따르는 분말 성형체의 말기 치밀화 모델)

  • Yang, Hoon-Chul;Kim, Ki-Tae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.7
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    • pp.930-939
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    • 2004
  • Constitutive models for final stage densification of metal powder compacts with power-law creep deformation were investigated. The constitutive models were implemented into a finite element program (ABAQUS) by using user subroutine CREEP and, from FEM results, useful densification curves were obtained when hydrostatic and uniaxial stress were applied to the powder compacts at various pressures and temperatures. Because the densification behavior varied as the constitutive models, the equivalent stress surface on each constitutive equation was investigated to analyze the difference of densification behavior.

Effect of power law index for vibration of armchair and zigzag single walled carbon nanotubes

  • Khadimallah, Mohamed Amine;Hussain, Muzamal
    • Steel and Composite Structures
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    • v.37 no.5
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    • pp.621-632
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    • 2020
  • This research deals with the study of vibrational behavior of armchair and zigzag single-walled carbon nanotubes invoking extended Love shell theory. The effects of different physical and material parameters on the fundamental frequencies are investigated. By using volume fraction for power law index, the fundamental natural frequency spectra for two forms of single-walled carbon nanotubes are calculated. The influence of frequencies against length-to-diameter ratios with varying power law index are investigated in detail for these tubes. To discretize the governing equation in eigen-value form, wave propagation approach is developed. Complex exponential functions have been used and the axial model depends on boundary condition that has been described at the edges of carbon nanotubes to calculate the axial modal dependence. Computer software MATLAB is utilized for the frequencies of single-walled carbon nanotubes and current results shows a good stability with comparison of other studies.

A practical power law creep modeling of alloy 690 SG tube materials

  • Lee, Bong-Sang;Kim, Jong-Min;Kwon, June-Yeop;Choi, Kwon-Jae;Kim, Min-Chul
    • Nuclear Engineering and Technology
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    • v.53 no.9
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    • pp.2953-2959
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    • 2021
  • A new practical modeling of the Norton's power law creep is proposed and implemented to analyze the high temperature behaviors of Alloy 690 SG tube material. In the model, both the stress exponent n and the rate constant B are simply treated as the temperature dependent parameters. Based on the two-step optimization procedure, the temperature function of the rate constant B(T) was determined for the data set of each B value after fixing the stress exponent n value by using the prior optimized function at each temperature. This procedure could significantly reduce the numerical errors when using the power law creep equations. Based on the better description of the steady-state creep rates, the experimental rupture times could also be well predicted by using the Monkman-Grant relationship. Furthermore, the difference in tensile strengths at high temperatures could be very well estimated by assuming the imaginary creep stress related to the given strain rate after correcting the temperature effects on the elastic modulus.

A Study on the Interim Measures by Arbitral Tribunal in International Commercial Arbitration -Focus on the Korean Revised Arbitration Law and UNCITRAL Model Law - (국제상사중재에서 중재판정부에 의한 임시적 처분에 관한 고찰 -우리나라 개정 중재법과 UNCITRAL 모델중재법을 중심으로-)

  • YU, Byoung-Uk
    • THE INTERNATIONAL COMMERCE & LAW REVIEW
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    • v.76
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    • pp.21-47
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    • 2017
  • Interim measures by an arbitral tribunal aim to protect the parties' rights before or during arbitral proceedings for avoiding frustration of the final award in international commercial disputes. Even though decisions of the interim measure are expected to be performed by parties directly during the arbitral processing, it is not easy to be provided by the arbitral tribunals cause of lack the power to enforce their decisions directly against the parties. Particular court supports mechanism for enforcement directly to assistance to arbitral tribunal's decisions. Decisions on interim measures are provisional. Even though the arbitration is ongoing to request interim measure directly to the arbitral tribunal, relevant courts are able to ensure effective relief cause by the difficulty of limited rights of the arbitral tribunal. In this time both revised Korean Arbitration Act in 2016 and UNCITRAL 2006 revised Model Law are complemented to attach articles for recognition and enforcement of interim measures by arbitral tribunal during the arbitration processing. It could be possible to enforcement of decisions of interim measures by arbitral tribunal on the revised arbitration law. In this paper it is considered the problems and alternatives on related applicable articles and articles of recognition and enforcement for the interim measures by arbitral tribunal under the revised UNCITRAL Model law and Korean Arbitration Act.

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