• Title/Summary/Keyword: Single-core

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The Influence of Drawing Parameters on Sausaging and Critical Current of Bi-2223/Ag HTS Wires. (Bi-2223/Ag 고온 초전도 선재의 임계전류 및 소세징에 미치는 인발 조건의 영향)

  • 하홍수;오상수;하동우;김상철;권영길;류강식
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.11a
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    • pp.488-491
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    • 2000
  • Bi-2223/Ag superconducting wires have been mainly prepared by a powder-in-tube method. The drawing and the rolling are main processes to increase the core density and wire length. In the fabrication of long wire, especially, the drawing should be precisely controlled to assure the filament homogeneity. In this paper, the influences of drawing die angle, bearing length and reduction ratio on the sausaging and the critical current density of the wire are investigated. Single cored and multi-filamentary wires are fabricated by PIT method with different conditions. The core densities and sausaging in the wires are investigated and are discussed regarding their relationship to the I$_{c}$. It was made clear that the geometry of drawing die is sensitively dependent on the sausaging. The improvement of I$_{c}$ was achieved by reducing the die angle and high core density.ity.

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3D Hierarchical Heterostructure of TiO2 Nanorod/Carbon Layer/NiMn-Layered Double Hydroxide Nanosheet

  • Zhao, Wei;Jung, Hyunsung
    • Journal of Surface Science and Engineering
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    • v.51 no.6
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    • pp.365-371
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    • 2018
  • 1D core-shell nanostructures have attracted great attention due to their enhanced physical and chemical properties. Specifically, oriented single-crystalline $TiO_2$ nanorods or nanowires on a transparent conductive substrate would be more desirable as the building core backbone. However, a facile approach to produce such structure-based hybrids is highly demanded. In this study, a three-step hydrothermal method was developed to grow NiMn-layered double hydroxide-decorated $TiO_2$/carbon core-shell nanorod arrays on transparent conductive fluorine-doped tin oxide (FTO) substrates. XRD, SEM, TEM, XPS and Raman were used to analyze the obtained samples. The in-situ fabricated hybrid nanostructured materials are expected to be applicable for photoelectrode working in water splitting.

Whole-core analysis of Watts bar benchmark with three-dimensional MOC code STREAM3D

  • Murat Serdar Aygul;Wonkyeong Kim;Deokjung Lee
    • Nuclear Engineering and Technology
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    • v.56 no.8
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    • pp.3255-3267
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    • 2024
  • This paper presents a high-fidelity simulation of the Organization for Economic Co-operation and Development (OECD) Nuclear Energy Agency (NEA) 3D whole-core Watts Bar benchmark using the UNIST in-house STREAM3D (Steady State and Transient Reactor Analysis code with Method of Characteristics) neutronic code. The benchmark encompasses various whole-core exercises, including single physics problems, multiphysics simulations, and depletion problems. When comparing parameters during the zero-power physics tests, including ITC, DBW, CRW, and criticality tests, STREAM3D results indicate a strong agreement with the measured data and KENO-VI. The comparison with the MC21/CTF code in 3D HFP BOC condition demonstrated strong agreement, with only a 0.42% difference in the normalized radial power distribution, a 0.38 K difference in the RMS of the assembly coolant exit temperature, and a mere 4 ppm difference in CBC.

An ICF-Core Sets for Children and Youth With Cerebral Palsy Based Approach From a Physical Therapist Perspective: A Single Case Study (물리치료사의 관점에서 뇌성마비 아동과 청소년을 위한 ICF-Core Set을 기반으로 한 접근법의 효과: 단일 사례 연구)

  • Kim, Jeong-hui;Kim, Tae-ho
    • Physical Therapy Korea
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    • v.23 no.1
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    • pp.55-64
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    • 2016
  • Background: The International Classification of Functioning, Disability, and Health-core set (ICF-core set) for children and youth (CY) with cerebral palsy (CP) provides a useful conceptual framework and a guide for health care planning and measuring the changes brought by interventions across a multitude of dimensions from body functions to personal activities, social participation, and environmental factors for them. Objects: This single case study was reported to illustrate the use of a goal directed approach in applying the ICF-core set for CY with CP from a physical therapist perspective. Methods: An eleven year old boy with spastic CP, Gross Motor Function Classification System (GMFCS) level V, and his mother participated in an evaluation of his functioning state. The intervention goal was set through an interview using the ICF-core set, Canadian Occupational Performance Measure (COPM) and Goal Attainment Scale (GAS). Physical therapy was carried out on an outpatient basis using a goal directed approach for 30 min, 1 time/week during 12 weeks and the boy's gross motor function was assessed using the Gross Motor Function Measure (GMFM)-66 version (item set 2) before and after the intervention. Results: As measured by the boy's mother, the COPM score showed a meaningful clinical change (performance=mean 3.5, satisfaction=mean 2.5) and the T-score of GAS changed 34.4 after the goal directed approach. The GMFM-66 (item set 2) score changed from 31.8 to 38.7 and evaluation using the ICF-core set displayed improvement in 6 items of activity level between before and after the intervention. Conclusion: The ICF-core set for CY with CP is useful for understanding the overall functioning of CY with this condition and provides an opportunity to share and integrate information and opinions from different disciplines. We consider it as a useful tool in the universal language for the therapy and education of CY with CP.

A Performance Improvement of Linux TCP/IP Stack based on Flow-Level Parallelism in a Multi-Core System (멀티코어 시스템에서 흐름 수준 병렬처리에 기반한 리눅스 TCP/IP 스택의 성능 개선)

  • Kwon, Hui-Ung;Jung, Hyung-Jin;Kwak, Hu-Keun;Kim, Young-Jong;Chung, Kyu-Sik
    • The KIPS Transactions:PartA
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    • v.16A no.2
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    • pp.113-124
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    • 2009
  • With increasing multicore system, much effort has been put on the performance improvement of its application. Because multicore system has multiple processing devices in one system, its processing power increases compared to the single core system. However in many cases the advantages of multicore can not be exploited fully because the existing software and hardware were designed to be suitable for single core. When the existing software runs on multicore, its performance improvement is limited by the bottleneck of sharing resources and the inefficient use of cache memory on multicore. Therefore, according as the number of core increases, it doesn't show performance improvement and shows performance drop in the worst case. In this paper we propose a method of performance improvement of multicore system by applying Flow-Level Parallelism to the existing TCP/IP network application and operating system. The proposed method sets up the execution environment so that each core unit operates independently as much as possible in network application, TCP/IP stack on operating system, device driver, and network interface. Moreover it distributes network traffics to each core unit through L2 switch. The proposed method allows to minimize the sharing of application data, data structure, socket, device driver, and network interface between each core. Also it allows to minimize the competition among cores to take resources and increase the hit ratio of cache. We implemented the proposed methods with 8 core system and performed experiment. Experimental results show that network access speed and bandwidth increase linearly according to the number of core.

Movement Characteristics Analysis of Single Phase Transformer Winding Using Finite Element Method (유한요소법을 이용한 단상변압기권선의 운동특성해석)

  • Choi, Myoung-Jun;Kim, Hyung-Seok;Park, Il-Han
    • Proceedings of the KIEE Conference
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    • 1996.07a
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    • pp.104-106
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    • 1996
  • In this paper, the dynamic motion driven by electromagnetic force of transformer windings is modeled and its characteristics are numerically analyzed. The electromagnetic field is obtained using the 2D finite element method taking account of anisotropic property of iron core, and the electromagnetic force on the transformer winding is calculated from Lorenz's force formula using the field distribution result. The system motion equation driven by electromagnetic force and gravitational force is numerically analyzed using the 4-order Runge-Kutta algorithm. Above analyses procedure is applied to a single-phase core-type transformer to validate its algorithm.

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A Single DOF Magnetic Levitation System using Time Delay Control and Reduced-Order Observer

  • Park, Jung-Soo;Baek, Yoon-Su
    • Journal of Mechanical Science and Technology
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    • v.16 no.12
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    • pp.1643-1651
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    • 2002
  • Magnetic levitation systems are required to have a large operating range in many applications. As one method to solve this problem, Time Delay Control (TDC) is applied to a single-axis magnetic levitation system in this paper A reduced-order observer is utilized to estimate states excluding measurable states in the control law. The system consists of a square air-core solenoid and a circular permanent magnet attached on a plastic ball. Theoretical magnetic forces of the system are obtained on the basis of the location of the magnet around the solenoid. The magnetic levitation force is obtained by the experiment, and then compared with the theoretical one. As the results of the control experiments, the nonlinear controller (TDC : 1-2 ㎜) has a larger operating range than the linear controller (PD control : 1-1.4 ㎜), and is superior to linear. control in the robustness to the modeling uncertainty and the performance of the disturbance rejection.

Bridgeless Flyback PFC Rectifier Using Single Magnetic Core and Dual Output Windings

  • Shin, Jong-Won;Baek, Jong-Bok;Cho, Bo-Hyung
    • Proceedings of the KIPE Conference
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    • 2011.07a
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    • pp.145-146
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    • 2011
  • In this paper, a bridgeless flyback power factor correction (PFC) rectifier which uses single magnetic core is proposed. The proposed PFC rectifiers utilize bidirectional switch to handle both positive and negative input voltage without bridge diodes. A transformer with dual output windings enables the rectifier dispense with any additional magnetic component. The operation of the proposed flyback PFC rectifier is analyzed, and its higher efficiency than its conventional counterpart is verified by experiment.

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Thermally Stable Antireflective Coatings based on Nanoporous Organosilicate

  • Kim, Su-Han;Cho, Jin-Han;Char, Kook-Heon
    • Proceedings of the Polymer Society of Korea Conference
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    • 2006.10a
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    • pp.282-282
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    • 2006
  • Nanoporous organosilicate thin films were realized by the microphase separation of pore generating components mixed with an organosilicate matrix. The refractive index of such nanoporous organosilicate films can be tuned in the range of $1.40{\sim}1.22$. With a nanoporous single layer with n ${\sim}1.225,\;99.85\;%$ transmittance in the visible range was achieved. In order to overcome the limitation on the narrow wavelength for high transmittance imposed by single nanoporous thin films, bilayer thin films with different reflectance for each layer were prepared by inserting high refractive index layer with a refractive index of 1.447. It is demonstrated that the novel broadband antireflection coating with improved transmittance can be easily achieved by the nanoporous bilayer thin films described in present study.

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Quasi-Distributed Water Detection Sensor Based On a V-Grooved Single-Mode Optical Fiber Covered with Water-Soluble Index-Matched Medium

  • Kim, Dae Hyun;Kim, Kwang Taek
    • Journal of Sensor Science and Technology
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    • v.24 no.1
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    • pp.1-5
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    • 2015
  • The V-grooved single-mode fiber in which a surface part of the core was removed was investigated as a quasi-distributed water detection sensor. In the normal state, the V-grooved region is filled and covered with a specific RI (Refractive Index)-matched medium, and the sensor experiences minimal optical loss. As water invades the V-grooved region, the material is dissolved and removed, and a considerable optical loss occurs owing to the large RI difference between the fiber core and water. The experimental results showed the feasibility of the device as a sensor element of the quasi-distributed water detection sensor system based on general optical time domain reflectometry (OTDR).