• 제목/요약/키워드: power-law model

검색결과 644건 처리시간 0.029초

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

  • 이용훈;조병훈;류헌수;문영현
    • 대한전기학회논문지:전력기술부문A
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    • 제48권10호
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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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에너지 보존법칙과 전력계통 안정도 직접 해석법에서의 응용 (Energy Conservation Law and its application for Direct Energy method of Power System Stability)

  • 문영훈;이용훈;조병훈;류헌수;최병곤
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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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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COLOR GRADIENTS WITHIN GLOBULAR CLUSTERS: RESTRICED NUMERICAL SIMULATION

  • Sohn, Young-Jong;Chun, Mun-Suk
    • Journal of Astronomy and Space Sciences
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    • 제14권1호
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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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니켈 촉매 상에서 에탄으로부터 수소생산을 위한 반응기 사이징 (Reactor Sizing for Hydrogen Production from Ethane over Ni Catalyst)

  • 성민준;이경은;조정호;이영철;전종기
    • 청정기술
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    • 제19권1호
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    • pp.51-58
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    • 2013
  • 니켈 촉매 상에서 에탄의 수증기 개질 반응과 수성가스 전환반응 반응에 대한 반응속도 데이터를 얻기 위하여 반응온도와 반응물의 분압을 변화시키면서 반응 실험을 수행하였다. 반응속도 데이터를 사용하여 거듭제곱 속도식 모델(power law kinetic model)과 랭미어-힌쉘우드 모델(Langmuir-Hinshelwood model)의 매개변수를 구하였다. 또한 반응 속도 모델식을 적용하여 PRO/II를 이용한 공정 모사를 통해서 에탄의 수증기 개질 반응기 사이징(sizing)을 수행하였다. 에탄을 반응물로 하여 수증기 개질 반응을 수행한 결과, 단순한 거듭제곱 속도식 모델보다 표면반응에 의하여 반응속도가 결정되는 랭미어-힌쉘우드 모델이 보다 적합하였고, 수성가스 전환반응에 대한 반응속도식은 거듭제곱 속도식 모델이 적합함을 보였다. PRO/II 시뮬레이션을 통해서 수소 생산량에 필요한 반응기의 크기를 결정할 수 있었다.

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

  • 이강빈
    • 한국중재학회지:중재연구
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    • 제18권2호
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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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    • 제61권2호
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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.

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

  • 양훈철;김기태
    • 대한기계학회논문집A
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    • 제28권7호
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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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    • 제37권5호
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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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    • 제53권9호
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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.

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

  • 유병욱
    • 무역상무연구
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    • 제76권
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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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