• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.212-212
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• 2000

This study was performed to construct a hot strip speed measuring system and check over whether the measured speed can be used for improving the mass flow of the head-end part of a hot strip in the 7-stand finishing mill. Because the mass flow in hot rolling mill affects the looper operation and the thickness and width control of a strip, accurate measurement of strip speed ie important. The measured speed was compared with the roll speeds of No. 6 and No.7 stand to check the performance of the system and analyzed to find how to apply the speed. As a result, it is shown that the accuracy of the system is enough, strip thickness error can be reduced by -275∼+200$\mu\textrm{m}$ using the measured speed and the existing FSU model has low accuracy for predicting forward slip rate. A neural network was developed to calculate forward slip rate instead of FSU model. The test result of the neural network shows that the neural network is more accurate than the FSU model.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.89-94
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• 2006

The tire delivering power generated from engine to the ground pulls a vehicle to move. Radius of tires is changeable due to elasticity that depends on the speed of vehicle and traction force. The main objectives on this study are real time measurement of dynamic radius and slip ratio according to the speed and traction force. The dynamic radius is proportional to speed and traction force. According to measurement, the dynamic radius is increased about 3mm under 100km/h compared to stop. It is also increased about 1.5mm when a traction force is supplied as much as 4kN compared to no load state at low speed. There is no strong relationship between slip ratio and vehicle speed. The slip ratio is measured up to 4% under WOT at first stage gear. Through this research, the method of measuring dynamic radius and slip ratio is set up and is expected to be applied to the measurement of traction force in chassis dynamometer or accelerating and climbing ability.

• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.1
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• pp.42-48
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• 2008

The architecture of WSN based Vehicle Speed Measurement System is presented in this paper from Telematics Sensor Network(TSN) to Management System. To verify the feasibility of the system, we implemented the vehicle speed measurement system and evaluated the accuracy of velocity measured by the system in our testbed, an old highway located near Kyungbu highway. The system performed over 95% of accuracy at 80kmph from the measurement. In addition, the battery life time of the sensor node was evaluated by simulation analysis with real measured current consumption profiles. Assuming the maximum average daily traffic in 2005, the battery life time is expected to be over 1.6 year from the simulation result.

• Journal of the Korean Solar Energy Society
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• v.31 no.3
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• pp.1-7
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• 2011

In the performance test for wind turbines of medium and large, The reference met-mast should be installed for measurement reference wind speed as IEC 61400-12-1 standards and design of booms for mounted an anemometer must be considered exactly. Boom-mounted cup anemometer are influenced by flow distortion of the mast and the boom. Therefore design of booms must be important so that flow distortion due to booms should be kept below 0.5%. But, in some cases at size of met-mast structure, the distance of boom from mast is longer then measurement of wind speed is impossible because of oscillation of boom-mounted anemometer. In this paper, We measured a wind speed at several point from mast and boom and we analyzed the error of wind speed at each point of measurement. Also, we will suggest a correction method using the data curve fitting about errors of wind speed between each point of mounted anemometer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8C
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• pp.1104-1112
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• 2004

In this paper, we establish measurement methods of vibration frequency for three-dimensional behavior measurement of large-scale structure using laser and high-speed CCD camera. We project the diode laser having a smaller fluctuation on the object plane attached to the structure and measure the displacement of the structure using a precise relative measurement algorithm. When we use high-speed(120 frames/sec) CCD camera, we can measure the vibration frequency having the uncertainty within 0.5% by taking FFT on the displacement, from 0Hz to 40Hz. And we also confirm the reliability and economical string of the suggested measurement method of vibration frequency of the structure by showing the accuracy of displacement measurement using laser is comparable to that of relative positioning methods using GPS.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1324-1335
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• 2016

This article explores the speed regulation problem of permanent magnet synchronous motor (PMSM) systems subjected to unknown time-varying disturbances. A continuous sliding mode control (CSMC) technique is introduced for the speed loop to enhance the robustness of PMSM systems and eliminate the chattering phenomenon caused by high-frequency switch function in the conventional control law. However, the high control gain of the CSMC law in the presence of strong disturbances leads to large steady-state speed fluctuations for PMSM systems. In many application fields, PMSM systems are affected by time-varying disturbances instead of constant disturbances. For example, electric bicycles are usually affected by changing environmental disturbances, including wind speeds, road conditions, etc. These disturbances may be in the form of constant, ramp, and parabolic disturbances. Hence, a generalized proportional integral (GPI) observer is employed to estimate these types of disturbances. Then, the disturbance estimation method and the aforementioned CSMC method are combined to establish a composite sliding mode control method called the CSMC+GPI method for the speed loop of PMSM systems. Contrary to the conventional sliding mode control technique, the proposed method completely eliminates the chattering phenomenon caused by the switching function in the conventional control law. Moreover, a small control gain for the CSMC+GPI method is chosen by feed-forwarding estimated values to the speed controller. Hence, the steady-state speed fluctuations are small. The effectiveness of the proposed control scheme is verified by simulation and experimental result.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.18-18
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• 2010

Methods of the characteristics evaluation of turbo-molecular pumps (TMP) are well-defined in the international measurement standards such as ISO, PNEUROP, DIN, JIS, and AVS. The Vacuum Center in the Korea Research Institute of Standards and Science has recently designed, constructed, and established the integrated characteristics evaluation system of TMPs based on the international documents by continuously pursuing and acquiring the reliable international credibility through measurement perfection. The measurement of TMP pumping speed is normally performed with the throughput and orifice methods dependent on the mass flow regions. However, in the UHV range of the molecular flow region, the high uncertainties of the gauges, mass flow rates, and conductance are too critical to precisely accumulate reliable data. With UHV gauges of uncertainties less than 15% and a calculated conductance of the orifice, about 35% of pumping speed uncertainties are experimentally derived in the pressure range of less than $10^{-6}$ mbar. In order to solve the uncertainty problems of pumping speeds in the UHV range, we introduced an SRG with 1% accuracy and a constant volume flow meter (CVFM) to measure the finite mass flow rates down to $10^{-3}$ mbar-L/s with 3% uncertainty for the throughput method. In this way we have performed the measurement of pumping speed down to less than $10^{-6}$ mbar with an uncertainty of 6% for a 1000 L/s TMP. In this article we suggest that the CVFM has an ability to measure the conductance of the orifice experimentally with flowing the known mass through the orifice chambers, so that we may overcome the discontinuity problem encountering during introducing two measurement methods in one pumping speed evaluation sequence.

• International Journal of High-Rise Buildings
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• v.8 no.4
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• pp.313-324
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• 2019

This paper presents the analysis of wind speeds data measured on top of three neighboring high-rise buildings close to a beach in Xiamen city, China, during Typhoon "Usagi" 2013. Wind tunnel simulation was carried out to validate the field measurement results. Turbulence intensity, turbulence integral scale, power spectrum and cross correlation of recorded wind speed were studied in details. The low frequency trend component of the typhoon speed was also discussed. The field measurement results show turbulence intensity has strong dependence to the wind speed, upwind terrain and even the relative location to the Typhoon center. The low frequency fluctuation could severely affect the characteristics of wind. Cross correlation of the measured wind speeds on different buildings also showed some dependence on the upwind terrain roughness. After typhoon made landfall, the spatial correlation of wind speeds became weak with the coherence attenuating quickly in frequency domain.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1404-1407
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• 2004

An electric railway system is composed of high-tech subsystems, among which main electric equipments such as transformers, converter and traction motors are critical components determining the performance of rolling stock. We developed a measurement system for on-line test and evaluation of performances of Korean High Speed Train. The measurement system is composed of software part and hardware part. Perfect interface between multi-users is possible. A new method to measure temperature was applied to the measurement system. By using the system, measurement and evaluation for the performance of electric equipments in Korean High Speed Train was conducted during test running.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1128-1133
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• 2006

The most important thing to secure safety and reliability of railway vehicles is to verify performance characteristics of equipments, and related companies or research institutes had many efforts to verify performances and functions of equipments synthetically and efficiently. KHST(Korean High Speed Train) has been developed by KRRI (Korea Railroad Research Institute). An electric railway system is composed of high-tech subsystems, among which main electric equipment such as transformers and converter are critical components determining the performance of rolling stock. We developed a measurement system for on-line test and evaluation of performances of KHST. The measurement system is composed of software part and hardware part. Perfect interface between multi-users is possible. A new method to measure temperature was applied to the ]measurement system. By using the system, fault diagnosis and performance evaluation of electric equipment in Korean High Speed Train was conducted during test running.