• Title/Summary/Keyword: Over-load

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Latching Current Limiter for Satellite (위성 탑재용 래칭 전류 리미터)

  • Kim, Du-Il;Kim, Hee-Jun;Han, Sang-Chul
    • Proceedings of the KIEE Conference
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    • 2005.07b
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    • pp.1368-1370
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    • 2005
  • Satellite is operated only with internal battery when separated from rocket. Internal battery is charged only from SAR(solar Array Regulator), solar cell. So battery will be exhausted and purpose of satellite will be failed if load module is out of order or short. This paper proposed real time current limiter which operated by telemetry of outer processor. This current limiter operates by control signal simultaneously cuts off over current by self over current sensing circuit. So it can reduce waste of battery energy and over load of outer processor.

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Overturning Resistance of Plain Concrete Piers in OSPG Railroad Bridges

  • Rhee, In-Kyu;Park, Joo-Nam;Choi, Eun-Soo
    • International Journal of Railway
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    • v.3 no.1
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    • pp.1-6
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    • 2010
  • The steel plate-girder bridges with concrete gravity piers have possibilities of overturning by lateral inertial force which can be reproduced by sudden earthquake attack. This paper explores an overturning mechanism of existing concrete gravity pier onto the sandy soil in the event of lateral push-over load by in-situ experimental observation. The in-situ push-over experiment for pier with earth anchors between spread footing and rock beds exhibits a reasonable enhancement of ductility against overturning. In unanchored system, a flexural crack at cold joint of concrete pier is not developed because of the over-turning of the pier. This leads a global instability (rotation) of pier-footing system with relatively low stresses in pier itself. While a lateral load is persistently increased in anchored system, the successive flexural cracking failure at cold joint is observed even after the local shear failure of soil due to redistribution of stress equilibrium between soil and pier structure as long as a tensile action of anchor cable is active.

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A QoS Provisioning Based on Load Balancing for Hand-over in OFDMA System (OFDMA 시스템에서 핸드오버를 위한 부하제어 기반의 QoS 제공 방안)

  • Lee, Jong-Chan;Lee, Moon-Ho
    • Journal of the Korea Society of Computer and Information
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    • v.18 no.2
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    • pp.59-68
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    • 2013
  • Efficient resource management and hand-over schemes are necessary to maintain consistent QoS because it may be severely defected by some delay and information loss during hand-over in LTE-Advanced networks. This paper proposes a resource management scheme based on the load control to support consistent QoS for heterogeneous services during hand-over in OFDMA based systems. Various multimedia services with different requirements for resource are able to be serviced simultaneously because service continuity can be provided by our proposed scheme. Simulation results show that it provides better performances than the conventional one with the measure of hand-over failure rate and packet loss rate.

Finite Element Analysis of Cracted Structural Steel Member (균열을 가진 강구조부재의 한계하중에 대한 유한요소해석)

  • 박용걸
    • Computational Structural Engineering
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    • v.8 no.1
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    • pp.123-126
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    • 1995
  • The purpose of the analysis is the numerical simulation of structures strained to the limit loads. The finite element calculations and experiments with cracked structures have been carried out yielding over limit strains between 10% and 15% by single peak load. Load versus displacement-diagrams and J-diagrams up to the limit load are calculated. By this way the influence of geometric parameters may be assessed in the post yield region. It is proposed to use such calculations to correlate experiments carried out with small specimens to experiments simulating the true dimensions of the design structure.

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A Study on the Behavior Character of Roadbed in High-Speed Railway Slab Tract (고속전철 슬레브궤도에서의 노반거동 특성에 관한 연구)

  • 조용권;이성혁;황선근
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.11a
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    • pp.319-326
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    • 2000
  • It is investigated character of the dynamic behavior at over excavation zone of roadbed using crushed stone instead of lean concrete. It is considered that behavior of roadbed using PENTAGON-3D and Baber's equation. Typical load of sine wave type using impact factor is compared to moving load system to examine relationship in using PENTAGON-3D case. Variations of this paper are material properties of roadbed, train velocity, subgrade bearing capacity. Using variations, safety of roadbed is estimated by dynamic behavior character.

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A Study on the Optimal Var Planning Considering Uncertainties of Loads (부하의 불확실성을 고려한 최적 Var배분 앨고리즘에 관한 연구)

  • 송길영;이희영
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.41 no.4
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    • pp.346-354
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    • 1992
  • In the power-system, the active and reactive power levels of load bus randomly vary over days, months, and years which are stochastic in nature. This paper presents an algorithm for optimal Var planning considering the uncertainties of loads. The optimization problem is solved by a stochastic linear programming technique which can handle stochastic constraints to evaluate optimal Var requirement at load bus to maintain the voltage profile which results in probabilistic density function by stochastic Load Flow analysis within admissible range. The effectiveness of the proposed algorithm has been verified by the test on the IEEE-30 bus system.

Multiple Installment Load Distribution Algorithm for Data Sets (균일한 길이 데이터 집합의 분할분배방식)

  • Kim, Hee-Won;Kim, Hyoung Joong;Lee, Jung-Moon
    • Journal of Industrial Technology
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    • v.15
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    • pp.33-40
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    • 1995
  • This paper presents a new method for load distribution in a single-level tree network equipped with front-end processors. This method focuses on effective data distribution over a number of processors minimize job processing time. Optimal multiple installment load distribution algorithm is presented. Minimum number of processors that maximizes efficiency is decided theoretically.

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An Evaluation of Tensile Characteristics of the Stress Aging Heat-treated SM45C Steel by Acoustic Emissions (음향방출법에 의한 SM45C 응력시효 처리재의 인장특성 평가)

  • Rhee, Zhang-Kyu;Park, Bog-Nam
    • Proceedings of the Safety Management and Science Conference
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    • 2009.04a
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    • pp.413-421
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    • 2009
  • This paper investigates tensile characteristics of the stress aging heat-treated SM45C steel which are aging temperature at $250^{\circ}C$, $300^{\circ}C$, aging time at 1, 3 hours, and applied load at 300, 400N conditions by using acoustic emission. Most suitable aging condition was aging temperature $300^{\circ}C$, aging time 1 hour, and aging applied load 300N. And increased yield load 28.3% than non-treatment specimen in this condition. AE energy in elastic limit increased about 16.7 times than non-treatment specimen. When aging time is 3 hours, yield load decreased than other conditions that possibility is high to have itself defect on inside the specimen or coarse grain size precipitation is different in happened over-aging phenomenon. Especially, in case of $300^{\circ}C$, 3 hours and 400N condition appeared AE energy in elastic limit fairly high about 30 times than non-treatment specimen. This is considered by emit a lot of energies when material causes plastic deformation because the ductility increases on specimen by over-aging phenomenon.

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The transient analysis for choosing the optimal SCR ratings of AC3 utilization category testing equipment used for electrical durability test for magnetic switch (IEC60947-4에 따른 전자개폐기 전기적 수명시험설비의 과도현상을 고려한 SCR최적 정격선정에 대한 연구)

  • Ryu Haeng Soo;Kim Kab Dong;Han Gyu Hwan
    • Proceedings of the KIEE Conference
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    • summer
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    • pp.354-356
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    • 2004
  • This paper is the transient analysis for choosing the optimal SCR ratings of AC3 utilization category testing equipment(AC3 TE) used for electrical durability test for magnetic switch according to IEC60947-4 Annex B by utilizing EMTP -ATPDraw. Magnetic contactor closes and opens the motor load with ON/OFF switch of electronic contactor. It is also used for protecting and controlling the load. Magnetic contactor detects the over-current flow in the load with a over-current relay and disconnects the load by opening its control power. The key cost of AC3 TE is the SCR ratings. The more decreases SCR ratings, the more decreased the cost is, but it is impossible to ensure the reliability. On the other hand, the more increases SCR ratings, the more increased the cost is. Thereupon, in this paper after the testing circuit is simulated by using EMTP-ATPDraw the SCR ratings will be applied in order to guarantee the testing reliability of PT&T(Power Testing and Technology institute in LG Industrial Systems Co.,Ltd.).

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Energy Saving Potentials of Dedicated Outdoor Air System in a High-rise Apartment Building (외기전담 시스템 기반 초고층 공동주택 중앙 환기시스템의 에너지 절감효과 분석)

  • Kim, Min-Hwi;Kim, Jin-Hyo;Kwon, Oh-Hyun;Jeong, Jae-Weon
    • 한국태양에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.291-296
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    • 2009
  • This paper investigates the energy saving potentials of a dedicated outdoor air system (DOAS) applied to a highrise apartment building. As for a typical $132-m^2$ apartment unit, two different HVAC systems; centralized DOAS-Ceiling Radiant Cooling Panel and decentralized Energy Recovery Ventilator-Packaged Air Conditioner were installed. Transient behavior and control characteristics of each system were modeled numerically using a commercial equation solver program, and annual cooling coil load and heating load reduction potentials were compared. The research shows that DOAS-Ceiling Radiant Cooling Panel system can reduce the cooling coil load over 21% annually compared with the current Energy Recovery Ventilator-Packaged Air Conditioner pair. In addition, over 40% of annual ventilation heating load can be reduced by use of DOAS.

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