• 제목/요약/키워드: core loss

검색결과 1,001건 처리시간 0.157초

비정질 재료의 자기특성에 미치는 자장중 열처리의 영향 (The Effect of Field Annealing on Magnetic Properties of Amorphous Alloy)

  • 김원태;장평우;이수형
    • 한국자기학회지
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    • 제7권4호
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    • pp.180-185
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    • 1997
  • 비정질 리본으로 제조된 링 코아 시편의 자장중 열처리 조건에 따른 철손 및 보자력 등의 연자기 특성 변화를 BH loop tracer를 이용하여 최대인가자기유도 0.1 T를 유지하면서 10 kHz에서 측정하였다. 열처리 시간이 증가함에 따라 코아의 철손 및 보자력은 감소하여 최소값에 도달한 다음 다시 증가한다. 공기 중에서 열처리한 경우의 시료가 Ar 분위기에서 열처리한 시료 보다 우수한 연자기 특성을 나타낸다. 코아의 원주방향으로 자장을 인가한 경우에는 인가자장의 세기가 6 Oe 이상이어야 자장중 열처리 효과가 나타나 철손 및 보자력이 감소하였으며, 냉각시 Curie 온도근처에서의 냉각속도가 빠를 수록 철손과 보자력은 감소한다. 코아의 폭 방향으로 자장을 인가한 경우에는 보자력의 증가와 투자율의 감소 및 약간의 철손 증가가 나타났다.

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New Mathematical Models with Core Loss Factor for Control of AC Motors

  • Shinnaka, Shinji
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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    • pp.630-635
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    • 1998
  • This paper establishes in a new unified manner new mathematical models with core(iron) loss factor for two kinds of AC motors, induction and synchronous motors which are supposed to generate torque precisely or/and efficiently under vector controls. Our new models consist of three basic equations consistent with the others such as differential equation describing electromagnetic dynamics, torque equation describing torque generating mechanism, energy transmission equation describing how injected energy is wasted, saved or transmitted where all vector signals are defined in general frame of arbitrary instant angular velocity. It is clearly shown in our models that equivalent core-loss resistance can express appropriately and separately both eddy-current and hysteresis losses rather than mere vague loss. Proposed model of induction motor is the most compact in sense of the number of employed interior states and parameters. This compact model can also represent eddy-current and hysteresis losses of rotor as well as stator. For synchronous motor, saliency is taken into consideration. As well known model for cylindrical motor can be obtained directly from salient one as its special case.

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Er 첨가 황화물계 광섬유의 제조 및 분광학적 특성 (Spectroscopic Properties of Er-doped Sulfide Fiber)

  • 최용규;임동성;김경헌;박세호;허종
    • 한국세라믹학회지
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    • 제37권8호
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    • pp.781-786
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    • 2000
  • An Er-doped sulfide fiber was drawn, and its spectroscopic properties were analyzed. Compositions of a 1000 ppmwt Er3+-doped core and an undoped clad were Ge30-Ga1-Asg-S61 and Ge30-As8-S62, in at.%, respectively. Refractive index of the core composition was approximately 0.01 high than that of the clad. In order to enhance the mechanical stability as well as to prevent infiltration of impurity ions such as OH-, an UV-curable polymer was used for the coating. The optical loss of a fiber formed directly from a polymer coated core rod without cladding was ∼15 dB/m at 1.06$\mu\textrm{m}$. In the case of a fiber with core/clad structure, the optical loss was so high that the stimulated emission of erbium fluorescence was not evident. It is believed that presence of inhomogeneous core/clad interface and crystalline aggregates precipitated in the clad region were responsible for the high optical loss. On the other hand, fluorescence characteristics of Er3+ embedded in the core region were more or loss deteriorate compared to fiber preform, which is attributed to the redistribution of the Er ions along with the partial crystallization of the core glass during the fiberization process.

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토로이드형 공심 초전도 변압기의 특성 (CHARACTERISTICS OF A SUPERCONDUCTING AIR-CORE TRANSFORMER OF TOROIDAL SHAP)

  • 최경달;한송엽
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1991년도 하계학술대회 논문집
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    • pp.27-30
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    • 1991
  • With the recent development of high performance AC superconducting wire of very small ac loss and large current carrying capacity, the possibility of superconducting air core transformer is being studied. The air core transformer has merits of no iron loss, no insulation to the core and no harmonics. But the air core transformer has large exciting current and low magnetic coupling factor. To increase the coupling factor, the transformer of toroidal shape is proposed and designed. (10KVA, 110/220V) Compared with air core transformer of solenoidal shape, the performance is improved. The exciting current occupies about 22% of the rated current.

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비대칭 U - 코어 고정자 구조를 가진 새로운 2상 영구자석 동기전동기의 특성해석 (Characteristic Analysis of A Novel Two-Phase Permanent Magnet Synchronous Motor with Asymmetric U-core Stator Structure)

  • 조비;;권병일
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2011년도 제42회 하계학술대회
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    • pp.1089-1090
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    • 2011
  • This paper presents a novel two-phase two-pole permanent magnet synchronous motor (PMSM) with asymmetric U-core stator structure. The construction and parameters of the novel two-phase U-core PMSM are compared with a conventional U-core single-phase PMSM (SPMSM). Then transient characteristics such as torque, back-emf, and power loss of the both PMSMs are analyzed by using 3-D Finite Element Method (FEM). Under the same condition of rated input current, synchronous speed, similar dimensions and volume, FE results show that the two-phase PMSM with U-core stator has significantly less torque ripple than single-phase U-core PMSM, with similar power loss and efficiency.

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A High Birefringent Polymer Terahertz Waveguide: Suspended Elliptical Core Fiber

  • Wang, Jingli;Chen, Heming;Shi, Weihua
    • Journal of the Optical Society of Korea
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    • 제18권5호
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    • pp.453-458
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    • 2014
  • A novel high birefringent polymer terahertz (THz) fiber with a suspended elliptical core is proposed in this paper. The introduction of an elliptical core can enhance asymmetry to realize high mode birefringence, and a large porous outer cladding effectively isolates the core-guided mode from interacting with the surrounding environment. A full-vector finite element method(FEM) is used to analyze the characteristics of the THz fiber. Simulation results show that the suspended elliptical fiber exhibits high mode birefringence on a level of $10^{-2}$ over a wide frequency range, and an extremely large mode birefringence(${\approx}0.06226$) is obtained when ellipticity is 0.2. Moreover, a suspended hollow elliptical core fiber is also discussed for the purpose of lower loss, however high mode birefringence and low relative absorption loss can not coexist in such a kind of fiber.

Neutron Spectrum Effects on TRU Recycling in Pb-Bi Cooled Fast Reactor Core

  • Kim Yong Nam;Kim Jong Kyung;Park Won Seok
    • Nuclear Engineering and Technology
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    • 제35권4호
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    • pp.336-346
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    • 2003
  • This study is intended to evaluate the dependency of TRU recycling characteristics on the neutron spectrum shift in a Pb-Bi cooled core. Considering two Pb-Bi cooled cores with the soft and the hard spectrum, respectively, various characteristics of the recycled core are carefully examined and compared with each other. Assuming very simplified fuel cycle management with the homogeneous and single region fuel loading, the burnup calculations are performed until the recycled core reached to the (quasi-) equilibrium state. The mechanism of TRU recycling toward the equilibrium is analyzed in terms of burnup reactivity and the isotopic compositions of TRU fuel. In the comparative analyses, the difference in the recycling behavior between the two cores is clarified. In addition, the basic safety characteristics of the recycled core are also discussed in terms of the Doppler coefficient, the coolant loss reactivity coefficient, and the effective delayed neutron fraction.

Gravity-Injection Core Cooling After a Loss-of-SDC Event n the YGN Units 3 & 4

  • Seul, Kwang-Woo;Bang, Young-Seok;Kim, Hho-Jung
    • Nuclear Engineering and Technology
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    • 제31권5호
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    • pp.476-485
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    • 1999
  • In order to evaluate the gravity-injection capability to maintain core cooling after a loss-of-shutdown-cooling event during shutdown operation, the plant conditions of the Yong Gwang Units 3&4 were reviewed. The six cases of possible gravity-injection paths from the refueling water tank (RWT) were identified and the thermal-hydraulic analyses were performed using the RELAP5/MOD3.2 code. The core cooling capability was significantly dependent on the gravity-injection path, the RCS opening, and the injection rate. In the cases with the pressurizer manway opening higher than the RWT water level, the coolant was held up in the pressurizer and the system pressure continued increasing after gravity-injection. The gravity injection eventually stopped due to the high system pressure and the core was uncovered. In the cases with the injection path and opening on the same leg side, the core cooling was dependent on whether the water injected from the RWT passed the core region or not. However, in the cases with the injection path and opening on the different leg side, the system was well depressurized after gravity-injection and the core boiling was successfully prevented for a long-term transient. In addition, from the sensitivity study on the gravity-injection flow rate, it was found that about 54 kg/s of injection rate was required to maintain the core cooling and the core cooling could be provided for about 10.6 hours after event with that injection rate from the RWT. Those analysis results would provide useful information to operators coping with the event.

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열확장 코어 광섬유의 구부림 손실을 이용한 광섬유형 온도 센서 (Fiber-optic Temperature Sensor Based on Bending Loss of Thermally Expanded Core Fiber)

  • 김광택;강지훈;조규정;문남일
    • 한국광학회지
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    • 제21권1호
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    • pp.12-15
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    • 2010
  • 본 논문은 바이메탈(bi-metal)에 부착된 열확장 코어 광섬유의 높은 구부림 손실 효과를 이용한 광섬유 온도 센서를 제안 및 구현하였다. 바이메탈(bi-metal plate)의 온도 변화에 의한 변형은 열확장 코어 광섬유의 구부림 손실을 발생시킨다. 실험결과 소자의 감도와 측정범위는 열확장 코어 광섬유의 구조를 조절하여 제어 될 수 있음을 보였다. 소자의 제조공정이 상세하게 기술되었다.

Microstructure and Soft Magnetic Properties of Fe-6.5 wt.%Si Sheets Fabricated by Powder Hot Rolling

  • Kim, Myung Shin;Kwon, Do Hun;Hong, Won Sik;Kim, Hwi Jun
    • 한국분말재료학회지
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    • 제24권2호
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    • pp.122-127
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    • 2017
  • Fe-6.5 wt.% Si alloys are widely known to have excellent soft magnetic properties such as high magnetic flux density, low coercivity, and low core loss at high frequency. In this work, disc-shaped preforms are prepared by spark plasma sintering at 1223 K after inert gas atomization of Fe-6.5 wt.% Si powders. Fe-6.5 wt.% Si sheets are rolled by a powder hot-rolling process without cracking, and their microstructure and soft magnetic properties are investigated. The microstructure and magnetic properties (saturation magnetization and core loss) of the hot-rolled Fe-6.5 wt.% Si sheets are examined by scanning electron microscopy, electron backscatter diffraction, vibration sample magnetometry, and AC B-H analysis. The Fe-6.5 wt.% Si sheet rolled at a total reduction ratio of 80% exhibits good soft magnetic properties such as a saturation magnetization of 1.74 T and core loss ($W_{5/1000}$) of 30.7 W/kg. This result is caused by an increase in the electrical resistivity resulting from an increased particle boundary density and the oxide layers between the primary particle boundaries.