• Title, Summary, Keyword: persistent

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The design, construction and operational characteristics of the superconducting persistent current switch (초전도 영구전류스위치의 설계. 제작 및 특성시험)

  • 오윤상;이상진;최경달;류강식;고태국
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.45 no.2
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    • pp.193-198
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    • 1996
  • Low power superconducting persistent current switch(PCS) for the superconducting magnet systems in the persistent mode was developed and its experimental results were analyzed when the system was charged or discharged. The multifilament NbTi wire with Cu matrix was used for the PCS. The constructed NbTi superconducting switch with superconducting magnet system operated successfully. It also operated on-off switching action with good stabilization. The maximum operating current in persistent mode was 60A (at 1T). In persistent current mode, the decay of the persistent current at 60A was observed. Its decay was 3.55% in 60 min. It is possible to make the persistent current switch with the better decaying of persistent current if some problems for joint resistance are solved.

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A Type 1 Persistent Proatlantal Artery Originating from the External Carotid Artery Detected by Computed Tomographic Angiography

  • Choi, Yunsuk;Chung, Sang Bong;Kim, Myoung Soo
    • Journal of Cerebrovascular and Endovascular Neurosurgery
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    • v.20 no.4
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    • pp.231-234
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    • 2018
  • A persistent proatlantal artery (PA) is rare. We report a type 1 persistent PA originating from the right external carotid artery (ECA). A 78-year-old woman presented with dizziness. Computed tomographic (CT) angiography showed a persistent PA originating from the right ECA. This persistent PA did not pass through the atlas transverse foramen. The extracranial segment of this artery in the atlas transverse process level had a more lateral position than a normal left vertebral artery. CT angiography well demonstrated the relationship with bony structures and the course of this persistent PA. This anomalous artery in our patient presented as an incidental finding. Surgeon should recognize a persistent PA when performing carotid endarterectomy or ligation of the ECA for avoidance of complication.

Chain Recurrence in Persistent Dynamical Systems

  • Chi, Dong Pyo;Koo, Ki-Shik;Lee, Keon-Hee;Park, Jong-Suh
    • Journal of the Chungcheong Mathematical Society
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    • v.3 no.1
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    • pp.1-11
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    • 1990
  • The purpose of this paper is to study the chain recurrent sets under persistent dynamical systems, and give a necessary condition for a persistent dynamical system to be topologically stable. Moreover, we show that the various recurrent sets depend continuously on persistent dynamical system.

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Fabrication method of persistent mode superconducting coils using tailored coated conductor (영구전류모드 운전을 위한 coated conductor의 가공 및 자석 제조)

  • Lee, Hee-Gyoun;Kim, Jae-Geun;Lee, Sun-Wang;Kim, Woo-Seok;Lee, Seung-Wook;Choi, Kyung-Dal;Hong, Gye-Won;Ko, Tae-Kuk
    • Progress in Superconductivity
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    • v.7 no.2
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    • pp.167-173
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    • 2006
  • Coated conductors suitable for the fabrication of persistent mode high $T_c$ magnets are suggested and the fabrication method of persistent mode magnets using coated conductor are demonstrated. Persistent current was observed in a small piece of coated conductor. Closed loop of coated conductor with a diameter of around 1 em was successfully prepared and was cooled with a magnetic field of about 500 Gauss in order to induce supercurrent. Coated conductor with a $I_c$ of 100 A/cm-width was used for the preparation of closed loop of coated conductor. Persistent current was confirmed by measuring the magnetic field generated from closed loop of coated conductor by using Gauss meter. Magnetic field of 4.4 Gauss was detected from the supercurrent of closed loop of coated conductor. It shows that superconducting joint of coated conductor is not a prerequisite for the construction of persistent mode magnets. It is thought that this work opens the possibility to use coated conductor for the construction of persistent mode high $T_c$ magnets for MRI, NMR and magnetic separation applications.

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Dynamic CSMA Protocol Based on the Network Status (네트워크 상태에 따른 동적 CSMA 프로토콜)

  • Lee, Wang-Jong;Rhee, Seung-Hyong
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.7 no.2
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    • pp.70-80
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    • 2008
  • CSMA(Carrier Sense Multiple Access) is a media access control protocol when nodes use a shared channel. To reduce the probability of collision and increase the performance, the station lust checks the state of the channel. In this paper, we study the performance improvement method based on p-persistent strategy. The p-persistent method reduces the chance of collision and improves the efficiency. However, a probability p and the number of station affect the performance. This paper proposes a dynamic CSMA multiple access based on the network status. If the possibility of collision is low, the station increases the probability p to improve the performance. In the opposite case, the station decreases the probability p. Our simulation results show that the proposed scheme outperforms any methods of CSMA multiple access according to the current persistent strategy.

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An Approach to Persistent Naming and Naming Mapping Based on OSI and IGM for Parametric CAD Model Exchanges (파라메트릭 CAD모델 교환을 위한 OSI와 IGM기반의 고유 명칭 방법과 명칭 매핑 방법)

  • Mun D.H.;Han S.H.
    • Korean Journal of Computational Design and Engineering
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    • v.9 no.3
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    • pp.226-237
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    • 2004
  • If the topology changes in the re-generation step of the history-based and feature-based CAD systems, it is difficult to identify an entity in the old model and find the same entity in the new model. This problem is known as 'persistent naming problem'. To exchange parametric CAD models, the persistent naming problem and the naming mapping problem must be solved among different CAD system, which use different naming scheme. For CAD model exchange the persistent naming has its own characteristics compare to that for CAD system development. This paper analyses previous researches and proposes a solution to the persistent naming problem for CAD model exchanges and to the naming mapping problem among different naming schemes.

Application-Adaptive Performance Improvement in Mobile Systems by Using Persistent Memory

  • Bahn, Hyokyung
    • International journal of advanced smart convergence
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    • v.8 no.1
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    • pp.9-17
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    • 2019
  • In this article, we present a performance enhancement scheme for mobile applications by adopting persistent memory. The proposed scheme supports the deadline guarantee of real-time applications like a video player, and also provides reasonable performances for non-real-time applications. To do so, we analyze the program execution path of mobile software platforms and find two sources of unpredictable time delays that make the deadline-guarantee of real-time applications difficult. The first is the irregular activation of garbage collection in flash storage and the second is the blocking and time-slice based scheduling used in mobile platforms. We resolve these two issues by adopting high performance persistent memory as the storage of real-time applications. By maintaining real-time applications and their data in persistent memory, I/O latency can become predictable because persistent memory does not need garbage collection. Also, we present a new scheduler that exclusively allocates a processor core to a real-time application. Although processor cycles can be wasted while a real-time application performs I/O, we depict that the processor utilization is not degraded significantly due to the acceleration of I/O by adopting persistent memory. Simulation experiments show that the proposed scheme improves the deadline misses of real-time applications by 90% in comparison with the legacy I/O scheme used in mobile systems.

Lived Experience of the Mother's Caring of Adult Children with Persistent Vegetative State (식물인간이 된 성인자녀를 돌보는 어머니의 체험)

  • Yang, Young-Mi;Kim, Jeung-Im
    • Korean Journal of Women Health Nursing
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    • v.23 no.4
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    • pp.287-298
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    • 2017
  • Purpose: The purpose of this study was to deepen understanding the nature of the care experience by the mothers with adult children in persistent vegetative state. Methods: Participants were 7 mothers caring for their adult children in persistent vegetative state. Data were collected individually through in-depth interviews on their lived experiences. Also texts were included as data from literary works, novels, movies, essays, and arts containing on patients with persistent vegetative state and their mothers. Data were analyzed by van Manen's phenomenological methodology. Results: The essential themes of caring experiences of the mothers were as follows. The theme in relation to lived time has shown as back to the past and caring experience related lived body has emerged as locked the body in children. The theme related lived space was getting into the swamp and the theme in lived others was derived as lonely struggle into. Conclusion: The nature of mothers' caring experiences for adult children in persistent vegetative state is summarized as 'Do not off hand of hope in a locked state'. This study suggests long-term supports are necessary for mothers to care persistent vegetative state children.

New Transient Request with Loose Ordering for Token Coherence Protocol (토큰 코히런스 프로토콜을 위한 경서열 트렌지언트 요청 처리 방법)

  • Park, Yun Kyung;Kim, Dae Young
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.54 no.10
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    • pp.615-619
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    • 2005
  • Token coherence protocol has many good reasons against snooping/directory-based protocol in terms of latency, bandwidth, and complexity. Token counting easily maintains correctness of the protocol without global ordering of request which is basis of other dominant cache coherence protocols. But this lack of global ordering causes starvation which is not happening in snooping/directory-based protocols. Token coherence protocol solves this problem by providing an emergency mechanism called persistent request. It enforces other processors in the competition (or accessing same shared memory block, to give up their tokens to feed a starving processor. However, as the number of processors grows in a system, the frequency of starvation occurrence increases. In other words, the situation where persistent request occurs becomes too frequent to be emergent. As the frequency of persistent requests increases, not only the cost of each persistent matters since it is based on broadcasting to all processors, but also the increased traffic of persistent requests will saturate the bandwidth of multiprocessor interconnection network. This paper proposes a new request mechanism that defines order of requests to reduce occurrence of persistent requests. This ordering mechanism has been designed to be decentralized since centralized mechanism in both snooping-based protocol and directory-based protocol is one of primary reasons why token coherence protocol has advantage in terms of latency and bandwidth against these two dominant Protocols.