• 제목/요약/키워드: DHC

검색결과 88건 처리시간 0.038초

다중 자기부상 시스템의 분산형 $H_{\infty}$ 제어 (Decentralized $H_{\infty}$ Control of Multiple Magnetic Levitation System)

  • 김종문;이상혁;최영규
    • 대한전기학회논문지:시스템및제어부문D
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    • 제54권12호
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    • pp.689-697
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    • 2005

  • In this paper, an application of a decentralized $H_{\infty}$ controller(DHC) to multiple controlled-permanent magnet(CMAG) magnetic levitation(Maglev) systems is presented. The designed DHC using two Riccati equations iteratively has simpler structure and needs less computational loads than conventional centralized $H_{\infty}$ controller. A target plant is a hybrid-type CMAG system with permanent magnet and coil, and its mathematical model is firstly derived to design the DHC. To implement the designed algorithm, a real Maglev vehicle system including digital controller, chopper, sensor, etc., is manufactured. To compare the performances of the DHC method with an observer-based state feedback control(OSFC), the input tracking and disturbance rejection characteristics are experimentally tested. As performance indices(PI), integral of squared error(ISE), integral of absolute error(IAE), integral of time multiplied by absolute error(ITAE) and integral of time multiplied by squared error(ITSE) are used. From the experimental results, it can be seen that the input tracking and disturbance rejection performances of the DHC are better than those of the conventional controller.

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가스터빈 복합발전의 기동특성을 고려한 열거래 기반 지역 냉난방 시스템의 최적 운영 모델 (Optimal Operation Model of Heat Trade based District Heating and Cooling System Considering Start-up Characteristic of Combined Cycle Generation)

  • 김종우;이지혜;김학만
    • 전기학회논문지
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    • 제62권11호
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    • pp.1610-1616
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    • 2013

  • Recently, district heating and cooling (DHC) systems based on combined cycle generation (CCG) providers are increasing in Korea. Since characteristics of combined heat and power (CHP) generators and heat demands of providers, heat trading between DHC providers based on the economic viewpoint is required; the heat trading has been doing. In this paper, a mathematical model for optimal operation based on heat trading between DHC providers is proposed. Especially, start-up characteristic of CCG is included. The operation model is established by mixed integer linear programming (MILP).

  • https://doi.org/10.5370/KIEE.2013.62.11.1610 인용 PDF KSCI KPUBS HTML

Improvement of delayed hydride cracking assessment of PWR spent fuel during dry storage

  • Hong, Jong-Dae;Yang, Yong-Sik;Kook, Donghak
    • Nuclear Engineering and Technology
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    • 제52권3호
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    • pp.614-620
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    • 2020

  • In a previous study, delayed hydride cracking (DHC) assessment of pressurized water reactor (PWR) spent fuel during dry storage using the threshold stress intensity factor (KIH) was performed. However, there were a few limitations in the analysis of the cladding properties, such as oxide thickness and mechanical properties. In this study, those models were modified to include test data for irradiated materials, and the cladding creep model was introduced to improve the reliability of the DHC assessment. In this study, DHC susceptibility of PWR spent fuel during dry storage depending on the axial elevation was evaluated with the improved assessment methodology. In addition, the sensitivity of affecting parameters such as fuel burnup, hydride thickness, and crack aspect ratio are presented.

  • https://doi.org/10.1016/j.net.2019.07.036 인용 PDF KSCI

Effect of Hydride Reorientation on Delayed Hydride Cracking In Zr-2.5Nb Tubes

  • Yun Yeo Bum;Kim Young Suk;Im Kyung Soo;Cheong Yong Moo;Kim Sung Soo
    • Nuclear Engineering and Technology
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    • 제35권6호
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    • pp.529-536
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    • 2003

  • The objective of this study is to investigate the reorientation of hydrides with applied stress intensity factor, the peak temperature and the time when to apply the stress intensity factor in a Zr-2.5Nb pressure tube during its thermal cycle treatment. Cantilever beam (CB) specimens with a notch of 0.5 mm in depth made from the Zr-2.5Nb tube were subjected to electrolytic hydrogen charging to contain 60 ppm H and then to a thermal cycle involving heating to the peak temperature of either 310 or $380^{\circ}C$, holding there for 50 h and then cooling to the test temperature of $250^{\circ}C$. The stress intensity factor of either 6.13 or $18.4\;MPa\sqrt{m}$ was applied at the beginning of the thermal cycle, at the end of the hold at the peak temperatures and after cooling to the test temperature, respectively. The reorientation of hydrides in the Zr-2.5Nb tube was enhanced with the increased peak temperature and applied stress intensity factor. Furthermore, when the CB specimens were subjected to $18.4\;MPa\sqrt{m}$ from the beginning of the thermal cycle, the reoriented hydrides occurred almost all over the Zr-2.5Nb tube, surprisingly suppressing the growth of a DHC crack. In contrast, when the CB specimens were subjected to the stress intensity factor at the test temperature, little reorientation of hydrides was observed except the notch region, leading the Zr-2.5Nb to grow a large DHC crack. Based on the correlation between the reorientation of hydrides and the DHC crack growth, a governing factor for DHC is discussed along with the feasibility of the Kim's DHC model.

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