• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.359-362
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• 2005

Road traffic noise level and railway noise level are important factors on apartment inhabitant's comforts. The measurement methods which noted by Ministry of Construction & Transportation(MOCT) and Ministry of Environment(ME) are used for measurement of exterior noise at apartment houses. But these methods are out of date because the height of apartment houses have increased dramatically and owing to the sampling methods of the measurement time interval, rating values are induced differently due to sampling methods. In this study, the sound level of each floor of apartment houses is measured and compared. And rating value due to sampling methods are compared. As a result, the KS outline of 'Field Measurement of Exterior Noise at Apartment Housess' is suggested.

• Safety and Health at Work
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• v.12 no.2
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• pp.230-237
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• 2021

Background: Noise-induced hearing loss is a well-known occupational disease that affects many fish harvesters from many fisheries worldwide, whose risk factor is prolonged exposure to hazardous noise levels. To date, academic research activities and regulatory bodies have not provided any comparative analysis among the existing methods to assess noise exposure levels of fish harvesters. This paper provides a comparison of four relevant assessment methods of noise exposure, examining the results of a measurement campaign performed onboard small fishing vessels from Newfoundland and Labrador. Methods: We traveled onboard 11 vessels engaged in multiple fisheries from Newfoundland and Labrador and performed extensive noise exposure surveys using the simplified International Maritime Organization method, the full-day measurement method, and the two methods provided by ISO 9612:2009, the task-based method and job-based method (JBM). Results: The results showed that the four methods yield similar values when the noise components are dominated by the engine and auxiliaries (steady-state sources); when noise components are dominated by the fishing gear, task-based method and the simplified International Maritime Organization method estimates are less accurate than JBM, using full-day measurements as baseline. Conclusion: The JBM better assesses noise exposure in small-scale fisheries, where noise exposure has significant variance and uncertainties on the exposure levels are higher.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.480-483
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• 2007

Recently, many apartment houses were built in nearby road and railway. Road traffic noise level and railroad traffic noise level are important factors on apartment houses inhabitant's acoustic comforts. The measurement methods which noted by Ministry of Construction & Transportation, Ministry of Environment and Korean Industrial Standard are used for measurement of exterior noise at apartment houses. The purpose of this study compare the noise level characteristic by the measuring methods and evaluating methods. The results show that road traffic noise in the daytime appeared by not greatly noise level difference by the measuring method and evaluating methods. But railroad traffic noise appeared by greatly the noise level difference by the equivalent noise level(1hour) and continuous time.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.424-432
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• 2000

The revision was provided for the method of A-weighted sound pressure measurement for fans and blowers, in which the newly developed measurement techniques were applied to KS B 6361. This revision includes the sound power methods for radiated sound from the body, the in-duct measurement method, and the correction method for flow noise upon measuring microphone, etc.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.6 s.99
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• pp.738-748
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• 2005

The ship radiated noise level fluctuates by the difference of interference and reverberation according to measurement methods and environmental conditions. These phenomena cause error of the source level estimation even in the same environment conditions. This paper describes a quantitative analysis and a reduction method for an error value to the source level estimation in spatial and temporal interference environment. The design criteria of the radiated noise measurement array composed of omni-directional hydrophones and the source level accuracy in the deep water range are given. The source level accuracy in the shallow water range is also derived based on the statistical model of the multiple reflection paths. The results are verified using the water tank experiment and the sea trial.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.255-260
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• 2006

Safety-critical navigation systems have to provide 'reliable' position solutions, i.e., they must detect and exclude measurement or system faults and estimate the uncertainty of the solution. To obtain more accurate and reliable navigation systems, various filtering methods have been employed to reduce measurement noise level, or integrate sensors, such as global navigation satellite system/inertial navigation system (GNSS/INS) integration. Recently, particle filters have attracted attention, because they can deal with nonlinear/non-Gaussian systems. In most GNSS applications, the GNSS measurement noise is assumed to follow a Gaussian distribution, but this is not true. Therefore, we have proposed a fault detection and exclusion method using particle filters assuming non-Gaussian measurement noise. The performance of our method was contrasted with that of conventional Kalman filter methods with an assumed Gaussian noise. Since the Kalman filters presume that measurement noise follows a Gaussian distribution, they used an overbounded standard deviation to represent the measurement noise distribution, and since the overbound standard deviations were too conservative compared to the actual distributions, this degraded the integrity-monitoring performance of the filters. A simulation was performed to show the improvement in performance of our proposed particle filter method by not using the sigma overbounding. The results show that our method could detect smaller measurement biases and reduced the protection level by 30% versus the Kalman filter method based on an overbound sigma, which motivates us to use an actual noise model instead of the overbounding or improve the overbounding methods.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.9
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• pp.657-662
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• 2022

In this paper, the calculation using simulation and two measurement methods for G/T of the telemetry are analyzed. Antenna gain and noise temperature are calculated by using ICARA and Antenna Noise Temperature Calculator. System G/T were calculated by using Antenna gain/noise temperature, LNA gain/noise temperature, cable loss. The first G/T measurement method is Y-factor measurement method, which is to calculate G/T by comparing LNA noise temperature and a signal level difference when an antenna and a 50ohm termination are respectively connected to an LNA input terminal Second method is Solar calibration measurement method that is to calculate G/T by comparing noise level difference when looking at the sun and lowest level point. Finally, the accuracy was reviewed by comparing the G/T calculation results with the two measurement methods, and the optimal measurement method according to antenna performance and operating environment was presented.

• Journal of the Korean Society of Safety
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• v.31 no.2
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• pp.90-97
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• 2016

The objective of this study is to evaluate the operator's safety for the risk assessment method of impulsive noise division. Literature reviews on the basis of the impulsive noise study, the measuring methods and procedures, based on the results of the analysis process presents a risk assessment methods. In this study, analysis of the MIL-STD-1474D, B-duration graph for the peak noise level to cross the line from the measurement results is limited by the risk retracted. It is possible to determine whether there is quick can be determined whether the risk. Measurement positions measured by the microphone is installed on the risk of applying results are so located within the tolerance impulsive noise in the measurement position can interpret subjective safety is ensured. In addition, Proportional Dose technology was the proposed by the Patterson with the risk assessment method was applied to the indoor-impulsive noise. As results of this study, results for the same value of applying the technique of Proportional Dose technology results calculated by MIL-STD-1474D methods allows 1 count once increased in comparison to the result obtained.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.12
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• pp.1260-1268
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• 2009

Three methods(the stepped sine method, the statistical method(random excitation method) and the maximum-length sequence(MLS) method) for head-related transfer functions(HRTFs) are experimentally compared in view point of accuracy and efficiency. First, the stepped sine method has high signal-to-noise ratio, but low efficiency. Second, the statistical method is fast measurement speed, but weak to noise than the other methods. Finally, the MLS method shows both good efficiency and high signal-to-noise ratio, but it needs additional software or equipment such as MLS signal generator. For comparison of measurement accuracy, HRTFs of KEMAR dummy are measured for various azimuths and elevations. Error norms for magnitude and phase of HRTFs are defined and calculated for the measured HRTFs. The calculated error norms show that the methods give similar results in magnitude and phase except a little phase difference in the MLS method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.3
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• pp.236-242
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• 2002

This paper presents some advanced and supplemental methods to enhance the accuracy In case of calculating geometric divergence attenuation, attenuation by multiple screening structures, ground attenuation at unflat surfaces of sound during propagation outdoors by the methods specified in ISO 9613-2. Moreover, a calculation method for considering short-term wind effect, specified in ASJ Model-1998, is also introduced. To verity the accuracy of adopted methods, we have carried out highway traffic noise prediction and measurement at tile twelve locations appearing representative road shapes and structures, such as flat, retained cut, elevated, barrier-constructed roads. From the results, we have confirmed the predicted results show good correspondence with the measured at direct, diffracted and reflected sound fields within 30 m from the center of near side lane.