• Title/Summary/Keyword: Iron core

검색결과 434건 처리시간 0.031초

Impoundments Increase Potential for Phosphorus Retention and Remobilization in an Urban Stream

  • Vo, Nguyen Xuan Que;Doan, Tuan Van;Kang, Hojeong
    • Environmental Engineering Research
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    • 제19권2호
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    • pp.175-184
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    • 2014
  • Weirs are conventional structures that control water level and velocity in streams to facilitate water resource management. Despite many weirs built in streams, there is little information how weirs change hydrology regime and how that translates to sediment and phosphorus (P) responses. This study evaluated the influence of weirs on P retention and mobilization in an urban tributary of the Han River in Korea. Total P concentrations in sediments upstream of weirs were higher than the downstream site, mainly due to the increase of potentially available fractions (labile P and aluminum- and iron-bound P) (p < 0.05). Equilibrium phosphorus concentrations ($EPC_o$) were lower than soluble reactive phosphorus (SRP) concentrations of stream waters, but there was an increasing trend of sediment $EPC_o$ upstream of weirs compared to the downstream site (p < 0.001) indicating a greater potential for P release upstream of weirs. Sediment core incubation showed that SRP release rates upstream of weirs were higher than the downstream site under anoxic conditions of the water column (p < 0.01), but not under oxic conditions. SRP release rates under anoxic conditions were greater than that measured under oxic conditions. Un-neutral pH and increased temperature could also enhance SRP release rates upstream of weirs. We conclude that weirs can increase P retention within stream sediments and potentially promote significant P releases into waters, which in turn cause eutrophication.

Simulation of the Reduction of Force Ripples of the Permanent Magnet Linear Synchronous Motor

  • Chung, Koon-Seok;Zhu, Yu-Wu;Lee, In-Jae;Lee, Kwon-Soon;Cho, Yun-Hyun
    • Journal of Electrical Engineering and Technology
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    • 제2권2호
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    • pp.208-215
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    • 2007
  • The significant drawback of the permanent magnet linear synchronous motor (PMLSM) is force ripples, which are generated by the distortion of the stator flux linkage distributions, cogging forces caused by the interaction of the permanent magnet and the iron core and the end effects. This will deteriorate the performance of the drive system in high precision applications. The PMLSM and its parasitic effects are analyzed and modeled using the complex state-variable approach. To minimize the force ripple and realize the high precision control, the components of force ripples are extracted first and then compensated by injecting the instantaneous current to counteract the force ripples. And this method of the PMLSM system is realized by the field oriented control method. In order to verify the validity of this proposed method, the system simulations are carried out and the results are analyzed. The effectiveness of the proposed force ripples reduction method can be seen according to the comparison between the compensation and non-compensation cases.

일체화된 삼성자속구속형 고온초전도 전류제한기의 퀜치특성에 관한 연구 (A Study on Quench Characteristics of HTSC Element in Integrated Three-phase Flux-lock Type Superconducting Fault Current Limiter)

  • 두승규;두호익;박충렬;최병환;김민주;김용진;한병성
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2007년도 추계학술대회 논문집
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    • pp.233-234
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    • 2007
  • We investigated the quench characteristics in integrated three-phase flux-lock type superconducting fault current limiter (SFCL), which consisted of three-phase flux-lock reactor wound on one iron core with the same turn's ratio between coil 1 and coil 2 for each single phase. To study the quench characteristics of the SFCL, the experiments was performed on various fault type such as the single line-to-ground fault, the double line-to-ground fault, the triple line-to-ground fault. From the experimental results, the generated point of element resistances was different on various fault type.

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사고전류 변화에 따른 일체화된 삼상자속구속형 고온초전도 사고전류제한기의 사고전류 제한 특성 분석 (Analysis of Fault Current Limiting Characteristics According to Variation of Fault Current level in Integrated Three-Phase Flux-Lock Type Superconducting Fault Current Limiting)

  • 한병성;박충렬;두호익;최효상
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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    • pp.39-40
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    • 2007
  • The analysis of fault current limiting characteristics according to variation of fault current level in the integrated three-phase flux-lock type superconducting fault current limiter (SFCL), which consisted of three-phase flux-lock reactor wound on an iron core with the same turn's ratio between coil 1 and coil 2 for each single phase, was performed. To analyze the current limiting characteristics of this integrated three-phase flux-lock type SFCL, the short circuit experiments was carried out the various three-phase faults such as the single line-to-ground fault, the double line-to-ground fault, the triple line-to-ground fault. From the experimental results, the fault current limiting characteristic was improved according to increase of fault current level.

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스페이서 내장형 ECT/EVT의 특성분석 (Characteristics Analysis of ECT/EVT within Epoxy Spacer)

  • 박성희;정해은;임기조;강성화;정종훈;김평중
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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    • pp.509-510
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    • 2006
  • 전류 및 전압을 측정하는 것은 오래전부터 CT(current transformer)/PT(potential transformer) 가 많이 사용되어져 왔지만, 이들은 iron core를 사용하기 때문에 포화특성이 발생하게 되어, 오차를 유발하게 된다. 이에 대한 대처 방안으로서 현재는 로고스키코일 및 분압방식을 이용한 ECT/EVT에 대한 적용이 진행이 되고 있다. ECT/EVT는 포화특성이 없고, 선형성이 매우우수하며, 소형, 경량이라는 점에서 현재 배전반의 변화 추세를 구현할 수 있는 충분한 능력을 지니고 있다. 이에 본 논문에서는 ECT/EVT를 제작하여, 특성을 분석하고자 한다. 특이점은 ECT/EVT가 EPOXY SPACER에 내장이 되어 사용이 되며, 이런 사용조건하에서의 이들의 특성이 변화 될 수 있는지를 살펴보았다. 그 결과 EPXOY 몰딩하에서도 그 선형성을 잃지 않았으며, 원하는 오차인 ${\pm}1%$에 부합되는 결과를 나타내었다.

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분리된 삼상자속구속형 전류제한기의 인덕턴스 변화에 따른 전류제한 특성 분석 (Analysis of Fault Current Limiting Characteristics According to Variation of Inductances in Separated Three-phase Flux-lock Type SFCL)

  • 두승규;두호익;김민주;박충렬;김용진;이동혁;한병성
    • 한국전기전자재료학회논문지
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    • 제22권6호
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    • pp.522-525
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    • 2009
  • We investigated the fault current characteristics of the separates three-phase flux-lock type superconducting fault current limiter(SFCL) according to the variation of inductances. The single-phase flux-lock type SFCL consists of two coils. The primary coil is wound in parallel to the secondary coil on an iron core. And superconductor is series connected on secondary coil. Superconductor is using the YBCO coated conductor. The separated three-phase flux-lock type SFCL consists of single-phase flux-phase type SFCL in each phase. To analyze the current limiting characteristics of a three-phase flux-lock type SFCL, the short circuit experiments were carried out fault such as the triple line-to-ground fault. The experimental result shows that fault current limiting characteristics of additive polarity winding was better than subtractive polarity winding and when the inductances of coil 2 was lower, resistances of YBCO CC was more generated.

A Study on the Compensation of the Inductance Parameters of Interior Permanent-Magnet Synchronous Motors Affected by the Magnet Size

  • Jang, Ik-Sang;Lee, Hyung-Woo;Kim, Won-Ho;Cho, Su-Yeon;Kim, Mi-Jung;Lee, Ki-Doek;Lee, Ju
    • Journal of Magnetics
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    • 제16권1호
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    • pp.74-76
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    • 2011
  • Interior permanent-magnet synchronous motors (IPMSMs) produce both magnetic and reluctance torques. The reluctance torque is due to the difference between the d- and q-axis inductances based on the geometric rotor structure. The steady-state performance analysis and precise control of the IPMSMs greatly depend on the accurate determination of the parameters. The three essential parameters of the IPMSMs are the armature flux linkage of the permanent magnet, the d-axis inductance, and the q-axis inductance. In the basic design step of an IPMSM, the inductance parameters are very important for determining the motor characteristics, such as the input voltage, torque, and efficiency. Thus, it is very important to accurately estimate the values of the motor inductances. The inductance parameters of IPMSMs have nonlinear characteristics along the magnet size because the iron core is saturated by the magnet and armature reaction fluxes. In this study, the inductance parameters were calculated using both the magnetic-equivalent-circuit method and the finite-element method (FEM). Then the calculated parameters were compensated by the saturation coefficient function, which was also calculated via the magnetic-equivalent-circuit method and FEM.

나노탄소물질을 함유하는 알루미늄기지 복합소재 개발 (Development of Aluminum Matrix Composites Containing Nano-carbon Materials)

  • 김정준;김대영;최현주
    • 한국분말재료학회지
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    • 제28권3호
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    • pp.253-258
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    • 2021
  • There is increasing demand for the development of a new material with high strength, high stiffness, and good electrical conductivity that can be used for high-voltage direct current cables. In this study, we develop aluminum-based composites containing C60 fullerenes, carbon nanotubes, or graphene using a powder metallurgical route and evaluate their strength, stiffness, coefficient of thermal expansion, and electrical conductivity. By optimizing the process conditions, a material with a tensile strength of 800 MPa, an elastic modulus of 90 GPa, and an electrical conductivity of 40% IACS is obtained, which may replace iron-core cables. Furthermore, by designing the type and volume fraction of the reinforcement, a material with a tensile strength of 380 MPa, elastic modulus of 80 GPa, and electrical conductivity of 54% IACS is obtained, which may compete with AA 6201 aluminum alloys for use in all-aluminum conductor cables.

MPS eutectic reaction model development for severe accident phenomenon simulation

  • Zhu, Yingzi;Xiong, Jinbiao;Yang, Yanhua
    • Nuclear Engineering and Technology
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    • 제53권3호
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    • pp.833-841
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    • 2021
  • During the postulated severe accident of nuclear reactor, eutectic reaction leads to low-temperature melting of fuel cladding and early failure of core structure. In order to model eutectic melting with the moving particle semi-implicit (MPS) method, the eutectic reaction model is developed to simulate the eutectic reaction phenomenon. The coupling of mass diffusion and phase diagram is applied to calculate the eutectic reaction with the uniform temperature. A heat transfer formula is proposed based on the phase diagram to handle the heat release or absorption during the process of eutectic reaction, and it can combine with mass diffusion and phase diagram to describe the eutectic reaction with temperature variation. The heat transfer formula is verified by the one-dimensional melting simulations and the predicted interface position agrees well with the theoretical solution. In order to verify the eutectic reaction models, the eutectic reaction of uranium and iron in two semi-infinite domains is simulated, and the profile of solid thickness decrease over time follows the parabolic law. The modified MPS method is applied to calculate Transient Reactor Test Facility (TREAT) experiment, the penetration rate in the simulations are agreeable with the experiment results. In addition, a hypothetical case based on the TREAT experiment is also conducted to validate the eutectic reaction with temperature variation, the results present continuity with the simulations of TREAT experiment. Thus the improved method is proved to be capable of simulating the eutectic reaction in the severe accident.

The treatment of coolant wastewater of rolling plate process by High Gradient Magnetic Separation

  • Kim, Tae-Hyung;Ha, Dong-Woo;Kwon, Jun-Mo;Sohn, Myung-Hwan;Baik, Seung-Kyu;Oh, Sang-Soo;Ko, Rock-Kil;Kim, Ho-Sup;Kim, Young-Hun;Park, Seong-Kuk
    • 한국초전도ㆍ저온공학회논문지
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    • 제11권4호
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    • pp.8-11
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    • 2009
  • This study introduced wastewater treatment method by High Gradient Magnetic Separation (HGMS). HGMS treatment was high efficient method for various industrial wastewaters. The system is currently research state, but we have surveyed commercialize the technology for industry. In rolling plate process, coolant wastewater was recycled by sedimentation and sand filter system. It needs several large reservoirs and long time to remove suspended solid (SS) like metal fines and iron oxide in hot rolling plate making process. If removing rate of suspended solid in rolling coolant wastewater is improved by using HGMS system, the productivity of working process can be increased and the area of reservoir can be reduced. We manufactured high temperature superconducting HGMS system that had a purpose to treatment of coolant wastewater in rolling plate process. We fabricated the prototypes of magnetic matrix filter consisting of stainless steel 430 mesh, which is a core component in the magnetic separation system, In our basic preliminary experiment using HGMS system, it has been clear that the fine paramagnetic particles in the coolant wastewater obtained from rolling plate process of POSCO can be separated with high efficiency.