• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.197-200
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• 2010

In some cases it is important to be able to measure not only the total sound intensity on a panel surface in a vehicle cabin, but also the components of that intensity due to sound radiation and due to absorption from the incident field. For example, these intensity components may be needed for calibration of energy flow models of the cabin noise. A robust method based on surface absorption coefficient measurement is presented in his paper.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.9 s.90
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• pp.819-826
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• 2004

A multi-step optimum strategy for the selection of the locations and directions of strain gauges is proposed in this paper to capture at best the modal response of blade in a series of modes on fan blades. It is consist of three steps including two pass reduction step, genetic algorithm and fine optimization to find the locations-directions of strain gauges. The optimization is based upon the maximum signal-to-noise ratio(SNR) of measured strain values with respect to the inherent system measurement noise, the mispositioning of the gauge in location and gauge failure. Optimal gauge positions for a fan blade is analyzed to prove the effectiveness of the multi-step optimum methodology and to investigate the effects of the considering parameters such as the mispositioning level, the probability of gauge failure, and the number of gauges on the optimal strain gauge position.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.12
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• pp.649-654
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• 2003

The simplest method for measuring output currents of the three phase inverters is to measure them with three current sensors such as hall sensors. This method requires at least two current sensors, and these types of sensors are somewhat expensive. More economical method is measuring DC link current with a simple shunt resistor, then, reconstructing output current using the DC link current value and the switching status. However, in low speed region, the measurement becomes difficult and even impossible due to the requirement of minimum switching duration for A/D conversion. These problems can be overcome by limitation of switching duration. Limitation of switching, however, causes voltage and current distortion. Owing to compensation, distortion can be effectively suppressed. However these increase acoustic noise due to increment of current ripple. In this paper, a current measurement method is proposed, which can reduce minimum switching duration resulting in reduction of acoustic noise. The validity of proposed method is confirmed through experiment.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.12
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• pp.1176-1181
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• 2010

This paper proposes three positioning algorithms using TOA measurements: 1) The well-known linearization method using Taylor series, 2) a modified Savarese method considering measurement noise, which does not need linearization, and 3) a modified Bancroft method where TOA measurements instead of pseudorange measurements are considered. Furthermore, through an error analysis, for Savarese method, divergence of altitude is anticipated if the transmitters are located at the same height. To prevent height divergence, the Savarese method is modified again for receivers which assumed moving on the even plane. Error analysis also shows the relationship between Bancroft and Savarese method. From the analysis it is expected that the performance of Savarese method is worse than Bancroft method because of error amplification during difference operation. Experiments using real TOA measurement from the time difference of ultra sound and RF validate the proposed methods and show that analysis is correct.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.6
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• pp.631-634
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• 2014

We propose a measurement state feedback controller for a class of nonlinear systems that have uncertain nonlinearity and sensor noise. The new design method based on the matrix inequality approach solves the measurement feedback control problem of a class of nonlinear systems. As a result, the proposed methods using a matrix inequality approach has the flexibility to apply the controller. In addition, the sensor noise can be attenuated for more generalized systems containing uncertain nonlinearities.

• Journal of Sensor Science and Technology
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• v.13 no.1
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• pp.1-11
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• 2004

Due to various types of errors added to dynamic weight measurement data, proper methods to reduce measurement errors are required to produce reliable weights. To cope with parasitic types of errors in real systems, information provided by the various sensors is utilized and combined in such a way to reduce the measurement errors of load cells. In addition to four channels of load cells from a trailer, an accelerometer is used to obtain the information to compensate the error induced from vertical movement of the vehicle due to the variation of ground level. A model trailer system is run to verify the effectiveness of the proposed method to reduce noise of dynamic weight measurements. Experiments show that the processed error magnitudes of less than 20 g can be obtained for 10 Kg experimental loads.

• Journal of the Korean Society of Safety
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• v.34 no.4
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• pp.95-102
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• 2019

The purpose of this study is to investigate the correlation between aluminum form work and noise-induced deafness by conducting special health examination on construction aluminum worker and noise measurement at the workplace. All the 11 aluminum form workers were diagnosed with noise-induced deafness after holding a special health examination. The workers have not had any previous history of noise-induced deafness which indicates that aluminum form work is related to noise-induced deafness disease. The impact noise of 120 dB(A)~125 dB(A), which exceeds the regulations of industrial safety and health act, was found during the dismantling rather than installation when noise measurement was made at the aluminum workplace. The aluminum form workers could permanently lose the hearing sense if they are exposed to this impact noise. This study is to suggest the method to prevent noise-induced deafness for aluminum form workers by firstly giving out hearing protection equipment at the construction site and secondly installing rubber mat, soundproof panel as well as changing the noise-lowering technique.

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.4
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• pp.174-183
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• 2021

This study aims to suggest a method to provide a real-time noise map based on cloud using Amazon AWS. Acquiring environmental noise information, an Android app was developed to collect data on noise level, location, and measurement time of campus in Inha Technical College as a study area. Noise measurement information is transmitted to the AWS Cloud and managed, and the noise information collected through Amazon Quick Site is displayed in charts and maps. Finally, a web-based noise contour map and the results mapped to buildings were visualized with a Google map for users to search for the current environmental noise distribution. The real-time noise map presented as a result of this study is expected to be helpful for noise status and reduction policies.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.167-169
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• 2014

Spray combustion has been used in many industrial fields, for instance, such as diesel engines, gas turbines and industrial furnaces, and furthermore various measurement techniques have been applied to elucidate the phenomenon of spray combustion. In order to measure simultaneously the droplet velocity and the droplet size of spray, Phase Doppler Anemometry (PDA) was frequently used in spray combustion. However, the measurement error is occurred due to existence of flame, which is considered as influencing the precision of measurement. Therefore, the purpose of this study is experimentally to conduct the systematic evaluation on the measurement error when PDA measurement is applied to combustion field.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.808-813
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• 2011

There are hundreds of thousands call center workers wearing acoustic device. However, researches and noise exposure measurements on the noise transmitted from acoustic devices have seldom been performed due to the difficulty of measurement and to the absence of the measuring method in Korea. The aim of this study is to set up management measures to protect hearing loss on the call operator by acquiring measurement data of noise transmitted from the headset Noise exposure measurements of 17 operators were performed in 7 call centers and Head and Torso Simulator method in compliance with the ISO Standard 11904-2 was used for the measurement of noise transmitted from the headset Sound pressure levels(SPL) transmitted from the headset were 73.2~86 dB(A). The operator exposed to the highest SPL set up his volume control at 9 which was the highest volume level. The volume control level, adjustable from 1 to 9, could be identified 12 out of 17 operators and the range of volume levels was 4.5~9. As a result of Pearson Correlation Analysis, the correlation between volume level and SPL transmitted from the headset showed high relation as significance at the 0.672 level(p<0.05). To protect hearing loss of call center operators, it is more practical and effective measure to limit the volume level below the noise exposure level, i.e. 85 dB(A), rather than to carry out noise monitoring considering cost-effective aspect.