• Journal of Korean Society of Water and Wastewater
• /
• v.28 no.5
• /
• pp.509-516
• /
• 2014

This study describes a reasonable planning method for water meter replacement which can minimize the metering under-registration for an increasement of revenue water. The increment analysis of real water usage was used to establish a replacement plan. The meter replacement database collected from K City was used as the basis of this analysis. The database included 964 connections of domestic and non-domestic consumers that had their meter replaced by aging at 2011. The result showed that the corelation between unregistered water volume and water meter age was lower than commonly expected where the current criteria of replacement is only water meter age(8 years) excluding the meters older than 13 years. And in the analysis result of water usage for 8 years, the total amount and increment of water usage had a significant effect on unregistered water volume. However the relation was different tendency as a total volume and slope of increment. In case of total water volume was larger than 10,000, larger than 7,000 and increment of 0.0 ~ -0.3, larger than 6,000 and increment more than -0.3 were analysed to need a replacement because of metering under-registration.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.23 no.10
• /
• pp.793-797
• /
• 2010

The basic performance of the ground system is evaluated as the ground resistance by applying low frequency current below 1 kHz. However, characteristics of the ground system should be analyzed by high frequency current up to 1 MHz since transient currents having a few hundred kHz component flow during a line-to-ground fault and/or a lightning strike. This paper deals with the design and fabrication of a wideband ground impedance meter (WGIM) which measures the impedance of ground systems in ranges from 65 Hz to 1.28 MHz. Also, a noise elimination algorithm using a digital bandpass filter is proposed. The maximum error of the WGIM is 4.91% in the measurement frequency range.

• Journal of the Korean Magnetics Society
• /
• v.15 no.1
• /
• pp.48-52
• /
• 2005

This paper describes a current sensor for precision current measurement of an electronic watt-hour meter that is going to install in houses in the future. As the current sensor is based on an cored principle (the Rogowski principle) it is not subject to usual limitations of saturation and non-linearity of general current transformers. An advantage of the developed current sensor is that non-linearity error in low current range is improved and the construction can be kept simple using an air core. We present a magnetic field analysis of the sensor using a finite-element solver. We compared the measured values versus the calculated values.

• Proceedings of the KWS Conference
• /
• 2008.05a
• /
• pp.15-15
• /
• 2008

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.41 no.6
• /
• pp.505-510
• /
• 2008

To understand the oceanographic characteristics of Hupo coastal waters as regards the East Korean Warm Current and the North Korean Cold Current, current direction and velocity were investigated by deploying a current meter in Hupo coastal waters during the summer and fall of 2007. Wind data were obtained from the homepage of the Korea Meteorological Administration. Water temperature was measured using a temperature meter attached to the current meter and a mini log. During summer, a south wind prevailed, while during the fall the wind blew from the north. Cold surface waters occurred on a large scale in summer, while in the fall, warm bottom water occurred frequently. After mid-November, when the surface water was cooler than $15^{\circ}C$, there was no difference in water temperature between the surface and bottom layers.

• Journal of Mechanical Science and Technology
• /
• v.18 no.2
• /
• pp.286-293
• /
• 2004

The air fuel ratios of current gasoline engines are almost controlled by several air flow meters. When CVVT (Continuous Variable Valve Timing) is applied to a gasoline engine for higher engine performance, the MAP (Manifold Absolute Pressure) sensor is difficult to follow the instantaneous air fuel ratio due to the valve timing effect. Therefore, a HFM (Hot Film Flow Meter) is widely used for measuring intake air flow in this case. However, the HFMs are incapable of indicating to reverse flow, the oscillation of intake air flow has an negative effect on the precision of the HFM. Consequently, the various duct configurations in front of the air flow sensor affect the precision of HFM sensitivity. This paper mainly focused on the analysis of the reverse flow, flow fluctuation in throttle upstream and the geometry of intake system which influence the HFM measurement.

• Journal of Korea Multimedia Society
• /
• v.20 no.7
• /
• pp.1046-1053
• /
• 2017

We propose a design method of high accuracy power measuring device and the method of securing the reliability of the measured data. As a design method for the development of the high accuracy power measuring device, the circuit was made by reflecting the high accuracy power measuring ICs and the CT (Current Transformer). To ensure the reliability of the power meter, we requested to the watt-hour meter certified testing organization to measure the error rate, and the error rate of active power based on the "Wattmeter Technical Standard(Revision notify 2014-283)" was measure, and the error rate was confirmed to be less than 0.1%.

• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.163-165
• /
• 1999

This work presents the performance characteristic of digital watthour meter under the harmonics of voltage and current. Each waveform involved is different in magnitude phase, and THD(Total Harmonic Distortion). It is possible to generate harmonics and control those waveforms using RTDS(Real Time Digital Simulator). Tests were performed on a selected sample of three-phase digital watthour meter which is coupled with data acquisition system via RS 485/232 converter. The percentage error rate of the watthour meter is compared for both sinusoidal and nonsinusoidal cases and the results are given.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.9 no.3
• /
• pp.101-106
• /
• 2009

Although ADCP(Acoustic Doppler Current Profiler) have been introduced and utilized for flow measurements since the end of 1990's, in-situ behavior performance of ADCP at stream gauging stations has not been evaluated in Korea. The purpose of this study is for verification and application of velocity measurements using a price meter and ADCP. The verification of measured velocities was carried out in a laboratory open-channel. The differences between the two velocity values measured by a pirce meter and ADCP are within 2.1%, which means that ADCP can be used at stream gauging stations. After verification, ADCP was applied to the Maekok stream selected as a test site for application. for application. The test application was performed by comparison of velocity results measured by ADCP and a price meter. Results show that the velocity values obtained by using ADCP coincide well with those by using conventional devices with the average measurement discrepancy of 10.5%.

• Journal of Korea Water Resources Association
• /
• v.53 no.12
• /
• pp.1071-1079
• /
• 2020

For integrated water management, it is essential to secure basic data such as the amount of agricultural water intake. The river water intake through the intake weir is carried out through the agricultural irrigation canal, and a method for measuring the quantity of water intake is required to suit the characteristics of the measuring points. In this study, the accuracy of the calculated flow data was determined by applying a microwave water surface current meter. The microwave water surface current meter is a method of calculating surface velocity using doppler effect, which is mainly used in high-velocities situations such as flood. Surface velocity is difficult to represent the average velocity of the entire section at low dicharges or high wind speeds, it is considered to be low in continuous utilization throughout the year, and it is necessary to verify whether the measurement using an microwave water surface curren meter is appropriate in agricultural irrigation canal. The data measured with an microwave water surface curren meter were compared with the actual flow data to calculate the intake data in agricultural irrigation canal. In agricultural irrigation canal, the low-level discharge calculated using an microwave water surface current meter at a minimum velocity of about 0.3 m/s and a minimum discharge of about 1.0 m3/s or higher was found to have a high tendency and accuracy compared to the standard discharge, especially when the high discharge was high. Although effective results can be obtained in terms of quantity at low discharge, it is deemed that subsequent studies are needed to calculate the average discharge of the cross section at low discharge, given that the trend of data is unstable. Through this study, it is suggested that it is appropriate to calculate the amount of water intake through the microwave water surface current meter in artificial waterways with a certain discharge or higher, so it is expected to be widely distributed as a method for measuring river water intake.