• Title/Summary/Keyword: Effective power

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Experimental study on the estimating effective horse power of a bottom trawl ship (저층 트롤선의 유효마력 산정에 관한 실험적 연구)

  • Wang, Woo-Kyung
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.41 no.3
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    • pp.227-233
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    • 2005
  • In order to estimate the effective horse power(EHP) in towing net of a bottom trawl ship, the ship's resistance was calculated by using a series data of Yamagata and Wigley formula. Also the effective horse power for a ship(EHPs) was estimated versus the ship speed in sailing and the propulsive efficiency was calculated with the brake horse power and the effective horse power. Then the effective horse power for a ship and a trawl net were estimated in the application of the propulsive efficiency in towing net. The total effective horse power($EHP_T$) was average 187.6kW and the effective horse power for a 1.awl net($EHP_n$) was average 176.7kW at a smooth sea state in towing net. The ratio of $EHP_n$ to $EHP_T$ was about 94.0% and the value was higher slightly than was already informed at a smooth sea state. The power for keeping up a townet speed was required more about 20% of a maximum continuous power at a rather rough sea state than a smooth sea state. In the future, if the residual resistance is considered with a sea state, $EHP_n$ will be estimated more correctly Also the data of EHP estimated by this method will be used as the basic data to design a trawl net.

Investigation on Effective Operational Temperature of HTS Cable System considering Critical Current and AC loss

  • Kim, Tae-Min;Yim, Seong-Woo;Sohn, Song-Ho;Lim, Ji-Hyun;Han, Sang-Chul;Ryu, Kyung-Woo;Yang, Hyung-Suk
    • KEPCO Journal on Electric Power and Energy
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    • v.2 no.2
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    • pp.307-310
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    • 2016
  • The operational cost for maintaining the superconductivity of high-temperature superconducting (HTS) cables needs to be reduced for feasible operation. It depends on factors such as AC loss and heat transfer from the outside. Effective operation requires design optimization and suitable operational conditions. Generally, it is known that critical currents increase and AC losses decrease as the operational temperature of liquid nitrogen ($LN_2$) is lowered. However, the cryo-cooler consumes more power to lower the temperature. To determine the effective operational temperature of the HTS cable while considering the critical current and AC loss, critical currents of the HTS cable conductor were measured under various temperature conditions using sub-cooled $LN_2$ by Stirling cryo-cooler. Next, AC losses were measured under the same conditions and their variations were analyzed. We used the results to select suitable operating conditions while considering the cryo-cooler's power consumption. We then recommended the effective operating temperature for the HTS cable system installed in an actual power grid in KEPCO's 154/22.9 kV transformer substation.

Spectral Efficiency 0f Symmetric Balance Incomplete Block Design Codes (Symmetric Balance Incomplete Block Design Code의 Spectral Efficiency)

  • Jhee, Yoon Kyoo
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.1
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    • pp.117-123
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    • 2013
  • By calculating the spectral efficiency of symmetric balance incomplete block design(BIBD) codes satisfying BER=$10^{-9}$, it can be found that ideal BIBD code design with m=2 and various q's is effective when effective power is high($P_{sr}=-10$ dBm). But BIBD code design with q > 2 and various m's can be effective when effective power is low($P_{sr}=-25$ dBm).

Dispersion Managed Optical Transmission Links with Optimized Optical Phase Conjugator

  • Lee, Seong-Real
    • Journal of information and communication convergence engineering
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    • v.7 no.3
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    • pp.372-376
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    • 2009
  • In this paper, new and simple optical transmission link with fixed dispersion management (DM) scheme, i.e., pre(post) compensation and residual dispersion per span (RDPS) are fixed to net residual dispersion (NRD) = 0 ps/nm, and optical phase conjugator (OPC) having optimal position depending on launch power in WDM transmission system is proposed. Also, effective launch power range of WDM channels resulting 1 dB eye opening penalty (EOP) is induced as a function of OPC position. First, it is confirmed that, for applying DM into WDM transmission link fixed pre(post)compensation and RDPS, which are independence on exact system parameters except launch power, sufficiently are used in WDM links, but OPC with optimal position is needed for effective compensating impairments of WDM channels. And, it is confirmed that effective launch power is broader in case of RDPS = 100 ps/nm than in RDPS = 50 ps/nm. But, it is shown that the best OPC position offset is -0.6 km from a point of view of power window, which is defined as difference between maximum and minimum effective launch power.

A Study on measurement for effective isotropic radiated power based power management of the base stations (등가등방성복사전력 기반의 기지국 출력 관리를 위한 측정 연구)

  • Lim, Jae-Choon;Kim, Jong-Heon;Moon, Sung-Won;Lee, Young-Hwan
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.10 no.6
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    • pp.118-125
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    • 2011
  • In this paper, a WCDMA experimental base station is constructed for power management of mobile communication base station and effective isotropic radiated power is determined by using received power of pilot channel measured on the line-of sight. The measurement system was constructed by a experimental base station and a measurement receiver and the common pilot channel (CPICH) power of the base station was measured. Effective isotropic radiated power (EIRP) of the base station obtained by the measurement value considering correction factor for the errors represented the difference of 0.5 dB compared to the established EIRP of the base station.

Effective Impulse Impedances of Deeply Driven Grounding Electrodes

  • Lee, Bok-Hee;Jeong, Dong-Cheol;Lee, Su-Bong;Chang, Keun-Chul
    • KIEE International Transactions on Electrophysics and Applications
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    • v.4C no.5
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    • pp.207-214
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    • 2004
  • This paper presents the characteristics of transient and effective impulse impedances for deeply driven grounding electrodes used in soil with high resistivity or in downtown areas. The laboratory test associated with the time domain performance of grounding piles subjected to a lightning stroke current has been carried out using an actual-sized model grounding system. The ground impedances of the deeply driven ground rods and grounding pile under impulse currents showed inductive characteristics, and the effective impulse ground impedance owing to the inductive component is higher than the power frequency ground impedance. Both power frequency ground impedance and effective impulse ground impedance decrease upon increasing the length of the model grounding electrodes. Furthermore, the effective impulse ground impedances of the deeply driven grounding electrodes are significantly amplified in impulse currents with a rapid rise time. The reduction of the power frequency ground impedance is decisive to improve the impulse impedance characteristics of grounding systems.

A Study on State Analysis of Substation Using PMU (PMU를 이용한 변전소 상태 해석에 관한 연구)

  • Tae-Hee Kim;Kyung-Min Lee;Cheol-Won Park;Dong-Hoon Jeon;Dae-Yoon Kwon;Yong-Sung Choi
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.37 no.3
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    • pp.304-308
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    • 2024
  • In this paper, in order to analyze the PMU data of the accident section, we collected the raw data of a total of 35 PMU installed at the Yeonggwang substation and tried to find a way to analyze the data, and analyzed the data using Excel format and formula. As a result, the three-phase voltage and current data of the PMU were calculated using formulas in Excel and interpreted as effective and reactive power, and it was possible to check the effective and reactive power of the accident section through the graph to see why it was different from before the accident. As a result, it was confirmed that each power was greatly reduced in the graph of the effective and reactive power of the accident section, and it was confirmed that the loss occurred as the power of the accident section was greatly reduced.

Three-Phase Hybrid Shunt Filters for Power Quality Improvement

  • Bhuvaneswari, G.;G.Nair, Manjula
    • Journal of Power Electronics
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    • v.7 no.3
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    • pp.257-264
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    • 2007
  • Active power filters can be cost-effective for use in practical systems with the insertion of a few passive elements in shunt or series configuration. The resulting hybrid filters can be designed to provide dominant lower order harmonic elimination and reactive power support by the passive elements so that the burden on the active filter counterpart is reduced. In this paper, the rate reduction in the shunt active filter is estimated when it is connected in parallel with suitable passive tuned harmonic filters. The active filtering system is based on an appropriate control scheme. The simulation and the experimental results of the shunt active filter, along with the estimated value of reduction in rating, show that the hybrid shunt filtering system is quite effective in compensating for the harmonics and reactive power, in addition to being cost-effective.

Calculation of Generator Reactive Reserve Considering Network Configuration (전력계통 구조를 고려한 발전기 무효예비력 산정)

  • Seo, Sang-Soo;Kim, Dae-Jeong;Choi, Yoon-Hyuk;Lee, Byong-Jun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.4
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    • pp.711-716
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    • 2011
  • This paper defines a generator reactive reserve considering power system network. Conventional generator reserve is calculated by the difference between the maximum reactive power output of generator and the current reactive power of generator. However, all generators could not affect on the whole power system. Thus, the effective generators should be selected by sensitivity analysis. The sensitivity depends on network configuration is the relation between generator reactive power outputs and reactive power loads. Using the sensitivity, the effective generator reactive reserve can be calculated.

Effective Capacity Calculation of the Electrical Energy Storage providing the Primary Frequency Control Service based on the Contribution to the Frequency Response of Power Systems (전력계통 주파수응답 기여도 기반의 전기저장장치 주파수추종서비스 유효용량 산정)

  • Lim, Hyeon Ok;Choi, Woo Yeong;Gwon, Han Na;Kook, Kyung Soo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.11
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    • pp.1561-1567
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    • 2017
  • This paper calculates the effective capacity of EES providing the primary frequency control service based on its contribution to the frequency response of the power system. The amount of governor response from conventional generators which can be replaced by the primary frequency control from EES keeping the frequency response of the power system is defined as the effective capacity. The proposed method for calculating the effective capacity of EES is verified through case studies employing Korean power system. Furthermore, the application of the effective capacity of EES to power system operation is also discussed.