• Title/Summary/Keyword: conservation integral

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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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Evaluation of Stress Intensity Factors and T-Stress Using a Conservation Integral (보존적분을 이용한 응력강도계수와 T-응력의 계산)

  • 범현규;엄윤용
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.1
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    • pp.121-126
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    • 1994
  • A mutual integral, which has the conservation property, is applied to the problem of a crack in an isotropic elastic material. The stress intensity factors $K_{I}, K_{II}, K_{III}$ and T-stress for the problem in an infinite medium are easily obtained by using the mutual integral without solving the boundary value problem. The auxiliary solutions necessary in the proposed method are taken from the known asymptotic solutions. This method is amenable to numerical evaluation of the stress intensity factors and T-stress if the crack in a finite medium is considered.

Mode Decomposition in Three Dimensional Cracks using Mutual Integrals

  • Kim, Young-Jong
    • International Journal of Precision Engineering and Manufacturing
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    • v.1 no.2
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    • pp.14-23
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    • 2000
  • A numerical scheme is proposed to obtain the individual stress intensity factors in an axisymmetric crack and in a three dimensional mixed mode crack. The method is based on the path independence of J and M integral and mutual or two-state conservation integral , which involves two elastic fields. Some numerical example are presented to investigate the effectiveness and applicability of the method for and axisymmetric crack and a three dimensional penny shaped crack problem under mixed mode.

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Mode Decomposition of Three-Dimensional Mixed-Mode Cracks using the Solution for Penny-Shaped Crack

  • Kim, Young-Jong;Cho, Duk-Sang
    • International Journal of Precision Engineering and Manufacturing
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    • v.2 no.3
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    • pp.11-18
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    • 2001
  • A simple and convenient method of analysis for obtaining the individual stress intensity factors in a three-dimensional mixed mode crack is proposed. The procedures presented here are based on the path independence of J integral and mutual or two-state conservation integral, which involves two elastic fields. The problem is reduced to the determination of mixed mode stress intensity factor solutions in terms of conservation integrals involving known auxiliary solutions. Some numerical examples are presented to investigate the effectiveness and applicability of the method for a three-dimensional penny-shaped crack problem under mixed mode. This procedure is applicable to a three-dimensional mixed mode curved crack.

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HIGHER ORDER SINGULARITIES AND THEIR ENERGETICS IN ELASTIC-PLASTIC FRACTURE (탄소성 균열 문제에서 고차응력특이성과 에너지론)

  • Jun, In-Su;Lee, Yong-Woo;Im, Se-Young
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.384-388
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    • 2001
  • The higher order singularities[1] are systematically examined, and discussed are their complementarity relation with the nonsingular eigenfunctions and their relations to the configurational forces like J-integral and M-integral. By use of the so-called two state conservation laws(Im and Kim[2]) or interaction energy, originally proposed by Eshelby[3] and later treated by Chen and Shield[4], the intensities of the higher order singularities are calculated, and their roles in elasticplastic fracture are investigated. Numerical examples are presented for illustration.

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Experimental Study on the MIMO Control Algorithm of a Multi-Heat Pump Based on PRBS Identification Scheme (PRBS 시스템 규명 기법 적용 멀티 열펌프의 다중입출력 제어특성에 관한 실험적 연구)

  • Choi, Jong Min
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.9 no.2
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    • pp.16-24
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    • 2013
  • A multi-heat pump provides the benefits of comfort, energy conservation and easy maintenance. Recently, the multi-heat pump has been widely employed in small and medium-sized buildings. However, the control algorithm of the multi-heat pump are limited in the open literature due to complicated operating conditions. In this study, the MIMO control algorithm using integral optimum regulator was designed and the control performance of it was analyzed. In addition, system model of the control plant was developed by PRBS system identification scheme. The MIMO controller adopting the integral optimum regulator yielded satisfactory control performance results.

Design of large-scale sodium thermal-hydraulic integral effect test facility, STELLA-2

  • Lee, Jewhan;Eoh, Jaehyuk;Yoon, Jung;Son, Seok-Kwon;Kim, Hyungmo
    • Nuclear Engineering and Technology
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    • v.54 no.9
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    • pp.3551-3566
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    • 2022
  • The STELLA program was launched to support the PGSFR development in 2012 and for the 2nd stage, the STELLA-2 facility was designed to investigate the integral effect of safety systems including the comprehensive interaction among PHTS, IHTS and DHRS. In STELLA-2, the long-term transient behavior after accidents can be observed and the overall safety aspect can also be evaluated. In this paper, the basic design concept from engineering basis to specific design is described. The design was aimed to meet similarity criteria and requirements based on various non-dimensional numbers and the result satisfied the key features to explain the reasoning of safety evaluation. The result of this study was used to construct the facility and the experiment is on-going. In general, the final design meets the similarity criteria of the multidimensional physics inside the reactor pool. And also, for the conservation of natural circulation phenomena, the design meets the similarity requirements of geometry and thermo-dynamic behavior.

The Applicability Evaluation of UV Indicators in the Exhibition Environment (전시환경에 대한 자외선 지시카드 적용성 평가)

  • Lim, BoA;Shin, EunJeong;Kim, MyoungNam;Lee, SunMyung
    • 보존과학연구
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    • s.33
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    • pp.85-97
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    • 2012
  • In this study, reliability assessment was carried out on UV(ultraviolet) indicators for the application of the indicator method on cultural heritages. As a result, some UV indicators(L, K, and M) proved to be unsuitable due to their low reactivity to UV and high reactivity to RH(relative humidity). On the other hand, indicator S showed considerable color changes and fading due to UV-B and UV-C according to the integral amount of UV irradiation. Indicator S showed the most distinct reaction to UV and a remarkable applicability to exhibition light, which are used in museums. Therefore, UV indicator S is an easy and useful monitoring tool for light environment management in cultural- property conservation facilities.

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Nonlinear stability of bio-inspired composite beams with higher order shear theory

  • Nazira Mohamed;Salwa A. Mohamed;Alaa A. Abdelrhmaan;Mohamed A. Eltaher
    • Steel and Composite Structures
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    • v.46 no.6
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    • pp.759-772
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    • 2023
  • This manuscript presents a comprehensive mathematical model to investigate buckling stability and postbuckling response of bio-inspired composite beams with helicoidal orientations. The higher order shear deformation theory as well as the Timoshenko beam theories are exploited to include the shear influence. The equilibrium nonlinear integro-differential equations of helicoidal composite beams are derived in detail using the energy conservation principle. Differential integral quadrature method (DIQM) is employed to discretize the nonlinear system of differential equations and solve them via the Newton iterative method then obtain the response of helicoidal composite beam. Numerical calculations are carried out to check the validity of the present solution methodology and to quantify the effects of helicoidal rotation angle, elastic foundation constants, beam theories, geometric and material properties on buckling, postbuckling of bio-inspired helicoidal composite beams. The developed model can be employed in design and analysis of curved helicoidal composite beam used in aerospace and naval structures.