• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.185-188
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• 2008

This paper introduces the Bootstrap method for statistical analysis of noise and vibration spectrum in aeronautic and space fields. Generally, all components of a launch vehicle and its payloads are subjected to high intensive noise and vibration environment during the lift-off phase and the ascent phase through Mach =1 and Max Q. In order to verify their survivabilities against these severe vibroacoustic environments during qualification tests and acceptance tests, it is most important to estimate the proper upper limits of the environmental condition. Although NASA has typically utilized the Normal Tolerance Limit method in deriving these levels, the reference[1] says that the Bootstrap can be also an alternative method to estimate the maximum expected environments. In this paper, a general procedure of the Bootstrap method is summarized, and it is applied to analyze acceleration power spectral density functions, which were measured during acoustic test on the upper stage of KSLV-I.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.11
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• pp.890-896
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• 2003

It is said that the goal of the design of good acoustical environment is at first the reduction of undesirable sounds. and in addition the introduction of desirable sounds by which our minds are soothed. The task of creating the desirable sounds leads to the realization of a comfortable acoustic environment and the design of soundscape. It may be an important starting point of soundscape design to select suitable sounds for the target spaces. because each space has a different surrounding condition and requires a special ambient sound. This paper aims to survey preference of the environmental sounds suitable for the public spaces in urban areas such as parks. bus terminals. 35 kinds of natural sounds are. rated by 26 pairs of adjectives. The results of psycho-acoustic experiments are as follows. 1. The proper adjectives for expressing the environmental sounds are classified into 6 groups of comfort, pleasure, fullness. variety, distinctness. and naturalness. 2. Bird singing. murmuring of a stream, artificial sounds. singing of insects and animals are the affirmative rank of preference. 3. Green musics consisted of music and natural sounds are preferred to the pure natural sounds. 4. Sound level relative to background noise causes various preferences to natural sounds in public spaces.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1010-1013
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• 2003

It is said that the goal of the design of good acoustical environment is at first the reduction of undesirable sounds, and in addition the introduction of desirable sounds by which our minds are soothed. The task of creating the desirable sounds leads to the realization of a comfortable acoustic environment and the design of soundscape. It may be an important starting point of soundscape design to select suitable sounds for the target spaces, because each space has a different surrounding condition and requires a special ambient sound. This paper aims to survey preference of the environmental sounds suitable for the public spaces in urban areas such as parks, bus terminals. 35 kinds of natural sounds are rated by 26 pairs of adjectives. The results of psycho-acoustic experiments are as follows. 1. The proper adjectives for expressing the environmental sounds are classified into 6 groups of comfort, pleasure, fullness, variety, distinctness, naturalness. 2. Bird singing, murmuring of a stream, artificial sounds, singing of insects and animals are the affirmative order of preference. 3. Green musics consisted of music and natural sounds are preferred to the pure natural sounds. 4. Sound level relative to background noise causes various preferences to natural sounds in public spaces.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2006.11a
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• pp.281-286
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• 2006

In case of Korea, immovable property like location, land prise or investment value is more highly estimated than quality of life of residents for performance and value of apartment house, because of limited land area or high density of population. But the high level of life has recently caused the increasing demand in better life. As there is no cases to provide the house in bulk due to the housing market condition, it is necessary to evaluate performance and value of structure, disaster prevention safety, habitability, antiquated condition of building and equipment, maintenance condition and so on that has importantly influence on resident's life quality. So, this study aims to understand the actual condition of environmental performance for the present apartment by comparing the designated apartment, which is ready to have completed in Daegu, with the mixed use residential building, which gained the best grade for green building certification system. Also by analyzing and evaluating a right to enjoy sunshine, floor impact noise etc. and indoor air quality.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.4
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• pp.991-998
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• 2010

In realization of wireless home network system using speech recognition in indoor voice recognition environment, background noise and reverberation are two main causes of digression in voice recognition system. In this study, the home network system resistant to reverberation and background noise using voice section detection method based on spectral entropy in indoor recognition environment is to be realized. Spectral subtraction can reduce the effect of reverberation and remove noise independent from voice signal by eliminating signal distorted by reverberation in spectrum. For effective spectral subtraction, the correct separation of voice section and silent section should be accompanied and for this, improvement of performance needs to be done, applying to voice section detection method based on entropy. In this study, experimental and indoor environment testing is carried out to figure out command recognition rate in indoor recognition environment. The test result shows that command recognition rate improved in static environment and reverberant room condition, using voice section detection method based on spectral entropy.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1987.04a
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• pp.191-195
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• 1987

When a 160QAM receiver in the band of spread spectrum system is interfered with a pseudo-random frequency-hopp-ing signal the interference signal has the form of the pulse amplitude probability density function. Each interfrering pulse amplitude probability density function Each interfering pulse amplitude is dependent upon theprobability density function of hopping frequency and the selectivity characteristic of 16QAM system in this paper the error rate equation of a system performance has been derived in the above condition which are interfrerence form and impulsive noise environmensts. The results of system analysis show us that the system performance is de-graded by impulsive noise and interference power, which improved as the frequency hopping bandsidth increases whit respect to receiver bandwidth

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.10
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• pp.1022-1028
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• 2006

A portable ECG sensor module and monitoring system which has the powerline noise reduction and the baseline wander removal is proposed. A small-szie ECG sensor H/W module with the 8-bits microprocessor is implemented. The ECG waveform can be inspected anytime with PDA in real time, and transmitted to the PC through wireless LAN. Portable ECG system can offer the environment that give the lasting medical service to the elderly and the long-time hospitalized patients at the wanted place, and the system can be attached to the chair, wheel chair, treadmill, elderly walker and used to monitor the health condition of man

• Proceedings of KOSOMES biannual meeting
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• 2006.05a
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• pp.207-212
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• 2006

The noise levels on board ship recognized at Europe in the early 1970s and the noise regulations on board ship began to put in a statutory form. After that, in 1982 "International Code on Noise Levels on Board Ships" adopted by IMO and it became standard to the newly built ship and remain so to this day. Especially, the ship engine room, which have huge main engine and various kinds of subsidiary machines, is under an extremely loud condition and so the worker who works in it is easy to lose his hearing. Recently, each nation regulates the allowable noise exposure time by law to protect the industrial employee from the occupational hardness of hearing. In our country, the allowable noise exposure time is regulated by the labor standard law but the international provisions regulated by IMO have been applied in case of the ship engine room. In this paper, the cabin's noise levels of cargo-passenger ships plies south-west coast line were investigated.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.3
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• pp.85-94
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• 2011

Spectrum sensing is one of the most important technologies in cognitive radio. Although many studies have considered energy detection technique as the spectrum sensing technique, noise variance in practical systems is difficult to estimate accurately. Thus, in the real system, the probability of false alarm will not be maintained constant. In this paper, with considering that the cognitive radio does not know the primary user's signal, we propose a new spectrum sensing scheme which can operate without the information of noise variance. Through simulations, we show that the proposed scheme can detect spectrum with the condition of unknown noise information and have robustness for the change of noise variance.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.2
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• pp.134-142
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• 2003

Most of the vibration and noise generating in small boats come from shipboard machinery such as main engine, generator and auxiliary machinery etc. In order to build up the comfortable environment for the crew and to reduce the ambient noise, and provide basic materials for reasoning selection application, the design under allowable vibration & noise conditions and the examination of vibration condition of the new ships, this paper researches the frequency spectrum and order analysis of vibration and noise. The obtained results are summarized as follows : Through comparing the small boat internal noise with the regulation of IMO and DNV, it revealed that the noise level of main engine room accords with the standard, and the noise of other places are beyond the values. In this paper, two boats are analyzed, which are same type, same size and power, but the main engines noise of them is different. In order to search the noise source, the noise of main engine room and relative parts are measured. The third order of measured points is dominant in frequency domain by the order analysis.