• Title, Summary, Keyword: Saturation Factor

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An Iron-cored CT Design Considering Overdimensioning Factor (과단면적 계수를 고려한 철심 변류기 설계 방법)

  • Lee, J.H.;Kang, S.H.;Lee, S.J.;Kang, Y.C.;Bae, J.C.;Ahn, J.K.
    • Proceedings of the KIEE Conference
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    • pp.834-836
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    • 1998
  • Current transformer (CT) saturation may cause a variety of protective relays to malfunction. The conventional CT is designed that it can carry up to 20 times the rated current. However, the possibility of CT saturation still remains, because the fault current may have substantial amounts of ac and/or de components. This paper presents a iron-cored CT design method to prevent CT saturation. The proposed method employs the overdimensioning factor $(K_{ta})$ considering dc components contained as well as symmetrical ac components in the fault current.

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AN ANALYTICAL DC MODEL FOR HEMTS (헴트 소자의 해석적 직류 모델)

  • Kim, Yeong-Min
    • ETRI Journal
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    • v.11 no.2
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    • pp.109-119
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    • 1989
  • Based on the 2-dimensional charge-control simulation[4], a purely analytical model for MODFET's is proposed. In this model, proper treatment of the diffusion effect in the 2-DEG transport due to the gradual channel opening along the 2-DEG channel was made to explain the enhanced mobility and increased thershold voltage. The channel thickness and gate capacitance are experssed as functions of gate vlotage including subthreshold characteristics of the MODFET's analytically. By introducing the finite channel opening and an effective channel-length modulation, the slope of the saturation region of the I-V curves was modeled. The smooth transition of the I-V curves from linear-to-saturation region of the I-V curves was possible using the continuous Troffimenkoff-type of field-dependent mobility. Furthermore, a correction factor f was introduced to account for the finite transtition section forming between the GCA and the saturated section. This factor removes the large discrepanicies in the saturation region fo the I-V curves presicted by existing 1-dimensional models. The fitting parameters chosen in our model were found to be predictable and vary over relatively small range of values.

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An Investigation of Induction Motor Saturation under Voltage Fluctuation Conditions

  • Ghaseminezhad, Morteza;Doroudi, Aref;Hosseinian, Seyed Hossein;Jalilian, Alireza
    • Journal of Magnetics
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    • v.22 no.2
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    • pp.306-314
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    • 2017
  • Nowadays power quality effects on induction motors have gained significant attention due to wide application of these motors in industry. The impact of grid voltage fluctuations on the induction motor behavior is one of the important issues to be studied by power engineers. The degree of iron saturation is a paramount factor affecting induction motors performance. This paper investigates the effects of voltage fluctuations on motor magnetic saturation based on the harmonic content of airgap flux density by finite element method (FEM). It is clarified that the saturation harmonics under normal range of voltage fluctuations have not changed significantly with respect to pure sinusoidal conditions. Experimental results on a 1.1 kW, 380 V, 50 Hz, 2 pole induction motor are employed to validate the accuracy of the simulation results.

Analysis of Slope Stability Considering the Saturation Depth Ratio by Rainfall Infiltration in Unsaturated Soil (불포화토 내 강우침투에 따른 포화깊이비를 고려한 사면안정해석)

  • Chae, Byung-Gon;Park, Kyu-Bo;Park, Hyuck-Jin;Choi, Jung-Hae;Kim, Man-Il
    • The Journal of Engineering Geology
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    • v.22 no.3
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    • pp.343-351
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    • 2012
  • This study proposes a modified equation to calculate the factor of safety for an infinite slope considering the saturation depth ratio as a new variable calculated from rainfall infiltration into unsaturated soil. For the proposed equation, this study introduces the concepts of the saturation depth ratio and subsurface flow depth. Analysis of the factor of safety for an infinite slope is conducted by the sequential calculation of the effective upslope contributing area, subsurface flow depth, and the saturation depth ratio based on quasi-dynamic wetness index theory. The calculation process makes it possible to understand changes in the factor of safety and the infiltration behavior of individual rainfall events. This study analyzes stability changes in an infinite slope, considering the saturation depth ratio of soil, based on the proposed equation and the results of soil column tests performed by Park et al. (2011 a). The analysis results show that changes in the factor of safety are dependent on the saturation depth ratio, which reflects the rainfall infiltration into unsaturated weathered gneiss soil. Under continuous rainfall with intensities of 20 and 50 mm/h, the time taken for the factor of safety to decrease to less than 1.3 was 2.86-5.38 hours and 1.34-2.92 hours, respectively; in the case of repeated rainfall events, the time taken was between 3.27 and 5.61 hours. The results demonstrate that it is possible to understand changes in the factor of safety for an infinite slope dependent on the saturation depth ratio.

Analysis of Saturation Flow Rate on Interrupted Flow During Rainfall (강우시 단속류 포화교통류율 변화 분석)

  • Kim, Bongseok;Roh, Chang-Gyun;Son, Bongsoo
    • Journal of Korean Society of Transportation
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    • v.33 no.1
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    • pp.90-99
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    • 2015
  • The climate of Korea has clear rainy and dry season due to seasonal wind. In general, The rainy season in Korea is from early summer through to early fall. And precipitation accounted for more than half of the total annual rainfall in this period. This study is aiming to analysis of variation in saturation flow rate at signalized intersection during rainfall. The range of spatial is urban signalized intersections in Seoul and temporal is rainfall or ideal condition in daylight. Traffic data are collected through CCTV of Seoul Metropolitan Police Agency, and on-site video recordings directly. Weather condition data are collected from the Korea Meteorological Administration. In addition, the value of saturation headway and saturation flow rate, in rainfall condition, are derived through video frame analysis. As a results of analysis, decrease of saturation flow rate and increase of saturation headway during rainfall were confirmed by comparison with non-rainfall. The higher rainfall rate is, the more decreased saturation flow rate at the intersections. Rainfall rate is divided three area by the results of statistical test, and saturation flow rate decrease 7%, 17%, 21%, respectively.

Capacity and Saturation Flow Rate of Permissive Left-Turn Lane: in case for the Exclusive Use of Permissive Left-Turn Movements (비보호(非保護) 좌회전(左回轉)의 간격수락(間隔受諾)과 용량(容量) 및 보정계수(補整係數)에 관한 연구)

  • Do, Cheol Ung
    • Journal of The Korean Society of Civil Engineers
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    • v.14 no.6
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    • pp.1273-1279
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    • 1994
  • There are 3 cases that only permissive left-turn(PLT) vehicles use the possible lane for PLT. In these cases, left turn and through movements can not be included in the same lane group, hence saturation flow rate and left turn adjustment factor of PLT are obtained separately from through movement. In capacity analysis procedures at signalized intersection with PLT phasing, PLT capacity should be known to discriminate among 3 cases stated above. The capacity is directly used not only to get saturation flow rate and left turn adjustment factor, but as a threshold for the feasibility of PLT control. This study calculated through field data the critical gap and minimum headway of left turn which affect the PLT capacity. The capacity was obtained by using theoretical models, which consequently could be used to calculate the saturation flow rate and left turn adjustment factor.

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Design of an Adaptive Noise Canceller for the Motion Artifact Removal of a Pulse Oximetry Signal (펄스 옥시미터의 동잡음 제거 필터 설계)

  • Kim, Do-Young;Kim, Ill-Hwan
    • Journal of Industrial Technology
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    • v.26 no.A
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    • pp.89-93
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    • 2006
  • Pulse oximetry, which monitors non-invasively the oxygen saturation in blood, is influenced by patient's respiration, movement or a factor of an environment. Specially, it's difficult to measure a PPG (Photoplethsmography) signal from the moving patient because of the motion artifact. Accordingly, it is required to extract the pure PPG signal from the PPG signal to measure oxygen saturation. In this paper, we propose an adaptive noise canceller to improve the performance of motion artifact removal. Then we design a hardware system for real time monitoring of the oxygen saturation. The proposed algorithm estimates the slope of transition rate between two different wavelength signals.

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Estimation of Saturation Depth by Reflecting Water-redistribution Phenomena at a Natural Slope (수분 재분포를 고려한 강우 침투 시 자연 사면에서의 포화깊이 산정)

  • Kim, Woong-Ku;Chang, Pyoung-Wuck;Cha, Kyung-Seob
    • Journal of The Korean Society of Agricultural Engineers
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    • v.48 no.1
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    • pp.71-79
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    • 2006
  • In Korea, most landslides occurred during the rainy season and had a shallow failure plane parallel to the slope. For these types of rainfall-induced failures, the most important factor triggering slope unstability is decrease in the matric suction of unsaturated soils with increasing saturation depth by rainfall infiltration. The saturation depth was readily estimated using modified Green-Ampt model proposed by Chu et al. (Chu Model) at present. But Chu Model involves some problems for application, because water-redistribution phenomena were not effected. So the modified Chu Model (MCGAM) which reflect water redistribution phono mens was developed. The results showed that the MCGAM had a better agreement with measured volumetric water contents than existing Chu Model.

Color Image Saturation enhancement algorithm using CIE $L^{\ast}U^{\ast}V^{\ast}$ color space (CIE $L^{\ast}U^{\ast}V^{\ast}$를 이용한 컬러 이미지 Saturation 향상 알고리즘)

  • Jo, Young-Sim;Cho, Hwa-Hyun;Choi, Myung-Ryul
    • Proceedings of the IEEK Conference
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    • pp.371-374
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    • 2005
  • A novel Color Image Saturation enhancement method to strengthen video images without producing oversaturated or color contour artifacts is proposed in this paper. Based on the luminance information, the relations between luminance levels and maximum chrominance vectors in each subcolor are generated for each pixel, so that the upper bound of the allowed saturation factor for a pixel can be derived, and much vivid video image can be achieved

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Estimation of Bus Saturation Flow Rates at Signalized Intersections Including Exclusive Median Bus Lanes (중앙버스전용차로가 설치된 신호교차로에서의 버스 포화교통류율 산정에 관한 연구)

  • Cho, Hanseon;Lee, Jae-Joon
    • Journal of Korean Society of Transportation
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    • v.31 no.3
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    • pp.65-73
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    • 2013
  • Exclusive median bus lanes were installed to mitigate congestions on urban traffic networks. However, capacity analysis of signalized intersections having exclusive median bus lanes have not been provided in current capacity analysis process(analyses). This study aims to develop a method of capacity analysis for lane groups consisting of only buses at the signalized intersections having exclusive median bus lanes. Finding basic saturation flow rates for buses is critical since the operational characteristics between automobiles and buses are fairly different. A total of 8 intersections in Seoul were chosen as study sites. Saturation headways, distances between bus-stop and stopline, and grades of each approach were measured at the sites. It was found that the basic saturation headway and the basic saturation flow rate of buses were 3.27 s/veh and 1,100pc/h/ln, respectively. Adjustment factor for upstream bus-stop locations was estimated with 0.50 and 0.75 when the distances between bus-stop and stopline are 20m and 70m, respectively. This study explains that bus saturation flow rates are decreased in half if the bus stop locates within 20 meters from stop lines.