• Title/Summary/Keyword: well loss

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Evaluation of Low or High Permeability of Fractured Rock using Well Head Losses from Step-Drawdown Tests (단계양수시험으로부터 우물수두손실 항을 이용한 단열의 고.저 투수성 평가)

  • Kim, Byung-Woo;Kim, Hyoung-Soo;Kim, Geon-Young;Koh, Yong-Kwon
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.10 no.1
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    • pp.1-11
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    • 2012
  • The equation of the step-drawdown test "$s_w=BQ+CQ^p$" written by Rorabaugh (1953) is suitable for drawdown increased non-linearly in the fractured rocks. It was found that value of root mean square error (RMSE) between observed and calculated drawdowns was very low. The calculated $C$ (well head loss coefficient) and $P$ (well head loss exponent) value of well head losses ($CQ^p$) ranged $3.689{\times}10^{-19}{\sim}5.825{\times}10^{-7}$ and 3.459~8.290, respectively. It appeared that the deeper depth in pumping well the larger drawdowns due to pumping rate increase. The well head loss in the fractured rocks, unlike that in porous media, is affected by properties of fractures (fractures of aperture, spacing, and connection) around pumping well. The $C$ and $P$ value in the well head loss is very important to interpret turbulence interval and properties of high or low permeability of fractured rock. As a result, regression analysis of $C$ and $P$ value in the well head losses identified the relationship of turbulence interval and hydraulic properties. The relationship between $C$ and $P$ value turned out very useful to interpret hydraulic properties of the fractured rocks.

The Influence of Parallel Magnetic Field on Magnetization Loss in a Bi-2223 Tape (수평자계가 Bi-2223테이프의 자화손실에 미치는 영향)

  • 한형주;류경우;최병주
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2001.02a
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    • pp.185-188
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    • 2001
  • Magnetization loss of a Bi-2223 tape in magnetic fields parallel to the tape surface was measured by a magnetization method. The results indicate that the magnetization loss is hysteretic because the measured loss agrees well with calculated one from a critical state model. In the full field penetration case the magnetization loss increases with the frequency but in the partial field penetration case the influence of the frequency is opposite.

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Round-robin Test on AC Losses in a Technical High-Tc Superconducting Tape (실용고온초전도테이프의 교류손실에 대한 Round-robin테스트)

  • 류경우;최병주;황시돌
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.53 no.7
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    • pp.437-443
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    • 2004
  • In this work the AC loss measurement setup based on an iron core background magnet, not used in a conventional one, has been successfully developed. To prove its validity, a round-robin test for the same Bi-2223 tape sample among three institutes has been done. The results show that the self-field and magnetization losses from the developed setup well agree with the losses measured at two other institutes of Korea Basic Science Institute and Yokohama National University. The measured magnetization losses for parallel or perpendicular fields can be well predicted from the slab model or the strip model for a filamentary region. However the magnetization losses for longitudinal fields can be rather predicted by the slab model for a decoupled filament. The self-field losses are well explained by the Norris ellipse model.

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

  • Shinnaka, Shinji
    • Proceedings of the KIPE Conference
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    • 1998.10a
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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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Does Loss-Leader Pricing Work in Online Shopping Malls?

  • Yeum Dai-Sung;Chae Myungsin;Kim Ji-Young
    • Management Science and Financial Engineering
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    • v.11 no.3
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    • pp.95-107
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    • 2005
  • As online shopping malls have emerged as a substantial shopping channel, they have used various sales promotion strategies to acquire new customers. Most of these strategies have been applied by offline malls for years. One, loss-leader pricing, is a type of promotional pricing in which stores sell well known products below their marginal cost, in order to attract customers and induce them to purchase more goods through impulse buying. This strategy is based on the expectation that customers will factor transaction costs into their purchasing decisions. However, its application to online malls fails to recognize that transaction costs are lower online, and that customers will behave differently as a result. Our study predicts that loss-leader pricing will not work online because online malls entail lower searching and moving costs than offline malls The study examines the effectiveness of loss-leader pricing with empirical data from a survey as well as log data from a Korean online shopping mall. The results show that while loss-leader pricing does attract customers to online shopping malls, it encourages cherry-picking rather than impulse purchases of regular-price goods.

A Practical Connection Admission Control Scheme in ATM Networks (ATM망에서 실용적 연결수락제어 기법)

  • Kang, Koo-Hong;Park, Sang-Jo
    • Journal of KIISE:Information Networking
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    • v.29 no.2
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    • pp.181-187
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    • 2002
  • Connection admission control(CAC), which decides whether or not to accept a new call request, is one of the most Important preventive congestion control techniques in asynchronous transfer mode(ATM) networks. To develop a practical CAC scheme, first we propose a "Modified Cell Loss Probability MP${\nu}"$, which is based on "Virtual Cell Loss Probability P${\nu}"$, taking into account mean burst duration of input traffic source and buffer size in ATM networks. MP${\nu}"$ computes more accurate cell loss probability than P${\nu}"$ without increasing computational complexity, since P${\nu}"$ is formulated simply form the maximum and the average cell rate of input traffic. P${\nu}"$ is overestimated as compared to the real cell loss probability when the mean burst duration is relatively small to the buffer capacity. Then, we Propose a CAC scheme, based on "Modified Virtual Bandwidth(MVB)" method, which may individualize the cell loss probabilities in heterogeneous traffic environments. For the proposed approach, we define the interference intensity to identify interferences between heterogeneous traffic sources and use it as well as MP${\nu}"$ to compute MVB. Our approach is well suitable for ATM networks since it provides high bandwidth utilization and guarantees simple and real time CAC computation for heterogeneous traffic environments.heterogeneous traffic environments.

Iron Loss Analysis Considering Excitation Conditions Under Alternating Magnetic Fields

  • Hong, Sun-Ki;Koh, Chang-Seop
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.3
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    • pp.33-38
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    • 2010
  • In this paper, the nature of iron loss in electrical steel during alternating field excitation is investigated more precisely. The exact definition of AC iron loss is cleared by accurately measuring the iron loss for conditions of both the sinusoidal magnetic field and sinusoidal magnetic flux density. The results of this approach to iron loss calculations in electrical steel are compared to experimentally-measured losses. In addition, an inverse hysteresis model considering eddy current loss was developed to analyze the iron loss when the input is the voltage source. With this model, the inrush current in the inductor or transformer as well as the iron loss can be calculated.

The Influence of External Magnetic Field on Transport Loss in a Bi-2223 tape (외부자계가 Bi-2223테이프의 통전손실에 미치는 영향)

  • 김창완;한형주;류경우;최병주
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2001.02a
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    • pp.169-171
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    • 2001
  • The transport loss of a Bi-2223 tape exposed to external magnetic field was investigated. The results show that the transport loss is independent on voltage lead arrangements in case the magnetization loss is compensated. An serious increase of the transport loss due to external magnetic fields is observed. The loss is described well by dynamic resistance loss in relatively high fields, but another mechanism than the dynamic resistance must be responsible for the increase of the loss in low fields. The transport loss is also dependent strongly on the orientation of the applied field.

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Accurate Transmission Loss Allocation Algorithm Based on the Virtual Transaction Strategy: Comparison of Path-integral with Discrete Integral Methods

  • Min, Kyung-Il;Moon, Young-Hyun
    • Journal of Electrical Engineering and Technology
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    • v.5 no.4
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    • pp.511-521
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    • 2010
  • This paper presents a new algorithm to determine accurate bus-wise transmission loss allocation utilizing path-integrals dictated by the transaction strategy. For any transaction strategy, the total sum of the allocated transmission losses of all buses is equal to the actual loss given by the AC power-flow calculation considering the distributed slack. In this paper, the bus-wise allocation of the transmission loss is calculated by integrating the differential loss along a path determined by the transaction strategy. The proposed algorithm is also compared with Galiana's method, which is the well-known transmission loss allocation algorithm based on integration. The performance of the proposed algorithm is evaluated by case studies carried out on the WSCC 9-bus, IEEE 14-bus, New England 39-bus, and IEEE 118-bus systems. The simulation results show that the proposed algorithm is fast and accurate with a large step size.

Study on the Power Loss of High Frequency Mn-Zn ferrites (고주파 Mn-Zn ferrites 전력손실에 대한 고찰)

  • 서정주
    • Resources Recycling
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    • v.11 no.5
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    • pp.34-38
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    • 2002
  • To minimize the size of transformer volume, the operating frequency of ferrites cores increasing. The power loss of Mn-Zn ferrites comprises hysteresis loss, eddy current loss and residual loss. In the range more then 500 KHz, the total power loss is mainly due to the residual loss. The power loss increase with the frequency 3rd power. To minimize residual loss as well as eddy current loss, the microstructure should have small grain and high density, It should be noted that as the product of resonance frequency and static permeability increase, the power loss decrease at high frequency region.