• The Research Journal of the Costume Culture
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• v.20 no.4
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• pp.475-484
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• 2012

The purpose of this study is to help to prevent daily noises by measuring the noise absorption coefficient of the non-woven fabrics and wallpapers which are commonly used in lining and noise absorption coefficient of lining curtain. Seven types of fiber materials for the interior decoration, one non-woven fabric for the wallpaper linings, and two types of textiles for curtain linings are used as the experimental materials in this study. The noise absorption coefficient of the noise absorbents were measured by using impedance tube. And the thermal transmittance were measured by using thermal transmittance tester. The results of this study are as follows; Observing the noise absorption efficiency of each experimental materials, the combination of fiber materials and linings, the noise absorption efficiency of cotton, polyester and silk were similar and for the experimental materials of flax, rayon, acrylic and nylon were resulted the similar noise absorption efficiency. The result of combination of fiber material and black fabric was highest among the combined linings. For the combination of fiber material and non-woven fabric, double layers of non-woven fabric resulted slightly higher noise absorption coefficient result than single layer of non-woven fabric. The thermal transmittance and the sound absorbents of experimental materials were affected by the thickness, density and layer of air of the experimental materials.

• Journal of Sensor Science and Technology
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• v.19 no.1
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• pp.43-51
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• 2010

In this study, wearable ECG measurement system was implemented for health monitoring during daily life. A wearable belt-type ECG electrode worn around the chest by measuring the real-time ECG is produced in order to minimize the inconvenience in wearing. The measured ECG signal is transmitted via an ultra low power consumption wireless data communications unit to personal computer using Zigbee-compatible wireless sensor node. The ECG monitoring program is developed at end user which is personal computer. The measured ECG contains many noises mainly due to motion artifacts. For ECG signal processing, adaptive filtering process is proposed which can reduce motion artifacts efficiently and accurately than digital filter. The experimental results show that a reliable performance with high quality ECG signal can be achieved using this wearable ECG monitoring system.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.1
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• pp.112-118
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• 2012

In daily life, there are many information broadcasting by using voice information systems. If surrounding noises are mixed with the information signals, the clarity of the signal become down graded too much to understand. Surrounding noises are not uniformed, but very irregular signals always changing. Therefore, it is very hard to control the output signals along with the irregular signals. This paper suggests a method to change the level of the voice information adapting to the surround noise in the white noise environment. The surround noise level is measured by subtracting the stored output voice signal from the voice signal degraded by the noise. The noise is used to estimation of SNR. And, the method to change the output level of voice signal adapting to the noise level. The suggested adaptive voice information system has the advantage to improve listeners' speech perception and to use amplifier's energy effectively.

• Korean Journal of Environmental Biology
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• v.27 no.4
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• pp.375-383
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• 2009

The aims of this study were wintering individuals, usage of foraging sites, potential food availability, daily activity and disturbance factors of White-naped Cranes Grus vipio on the wintering site, Han-river estuary, Goyang and Gimpo city, Korea. We want to provide basic data to conserve the cranes. Maxium population was identified 162 individuals at the middle of February in the river side and mud flat of this study area. Spring migration for breeding was started at the first week of March and finished for two weeks later. White-naped Cranes were used four feeding sites in winter; agricultural area in Hongdopyong, Yihwa-dong, Pyong-dong and Songpo-dong. Expected carrying capacity (ECC) was 334 days (121~909 days). White-naped Cranes departed from roosting site to feeding site at every morning for foraging. If they were disturbed by some factors at feeding sites, they moved to mud flat in the Han river to forage and take a rest. Daily activity was consisted of six category; feeding, alert, locomotion, preening, comfort, social and other behaviors. Feeding was the highest portion among behaviors in the wintering area. Feeding, alert, locomotion and preening in daily activities significantly differed among feeding sites. We watched total 348 times of disturbances in the wintering sites. Artificial disturbances were vehicles, humans, bicycles and motorcycles. Natural disturbances were noises, animals and others. Disturbances in all wintering sites were highest in Yihwa-dong (134 times) and followed by Hongdopyong (109 times), Songpo-dong (64 times) and then Pyong-dong (44 times). And artificial disturbances (228 times) were more than natural disturbances (120 times). Especially, vehicle was one of the most checked factor in the wintering area.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2E
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• pp.71-80
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• 2002

This paper suggests the Cardioid beamforming algorithm of the doublet sensors employing DIFAR (directional frequency analysis and recording) sensor signals in the frequency domain. The algorithm enables target bearing estimation using the signals from directional sensors. The algorithm verifies its applicability by successfully estimating bearings of a target projecting ten narrow-band signals in shallow water. The estimated bearings agree very well with those from GPS (global positioning system) data. Assuming the bearings from GPS data to be real values, the estimation errors are analyzed statistically. The histogram of estimation errors in each frequency have Gaussian shape, the mean and standard deviation dropping in the ranges -1.1°∼ 6.7°and 13.3∼43.6°, respectively. Estimation errors are caused by SNR (signal to noise ratio) degradation due to propagation loss between the source and receiver, daily fluctuating geo-magnetic fields, and non-stationary background noises. If multiple DIFAR systems are employed, in addition to bearing, range information could be estimated and finally localization or tracking of a target is possible.

• The Journal of Korean Physical Therapy
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• v.4 no.1
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• pp.59-67
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• 1992

This study was carried out by using questionnaires with 230 lumbago patients who visited the general hospitals, orthopedic clinics, neurosurgery clinics and physical treatment centers in Taequ. Korea for one month from December 20, 1991 to January 20, 1992. The result of this study is summarized as follows. 1. 203 patients consisted of 113 males and 90 females, while 65 patients were was which was the highest percentage. 2. The relation between their occupational properties and lumbago indicated that there was significant relation in their total employed period, job hours, monthly average incomes(P<0.01), job satisfaction, working posture, mental stress(P<0.01), excessive usage of bark during working, lifting of heavy thing and serious noises. 3. The relation between social properties and lunbago showed that there was a remarkable relation in their introspective character(P<0.05). daily average riding hour(P<0.05), smoking(P<0.01), drinking(P<0.01) and insufficient physical exercise. 4. The relation between the clinical properties and lunbago indicated that the lumbago was mainly caused by lifting the heavy thing, which was continued fur three months or longer. And, it was shown that they consider the lumbago as one of serious diseases. In addition. they positively evaluated their physical treatment. Therefore, it is required to accomplish the comprehensive treatment of this lumbago on the basis of the educational contents centering around its prevention by performing more suitable health education.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.2
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• pp.169-184
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• 2002

In order to extract bearing information from the directional sensors of DIFAR(directional frequency analysis and recording) that is a kind of passive sonobuoy, the cardioid beamforming algorithm applicable to DIFAR system was studied in the frequency domain. the algorithm uses narrow-band signals propagated though the media from the acoustic sources such as ship machineries. The proposed algorithm is expected to give signal to noise ratio of 6dB when it uses the maximum response axis(MRA) among the Cardioid beams. The estimated bearings agree very well with those from GPS data. Assuming the bearings from GPS data to be real values, the estimation errors are analyzed statistically. The histogram of estimation errors in each frequency have Gaussian shape, the mean and standard deviation dropping in the ranges -1.1~$6.7^{\circ}$ and 13.3~$43.6^{\circ}$, respectively. Estimation errors are caused by SMR degradation due to propagation loss between the source and receiver, daily fluctuating geo-magnetic fields, and non-stationary background noises. If multiple DIFAR systems are employed, in addition to bearing, range information could be estimated and finally localization or tracking of a target is possible.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.227-229
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• 2021

The modern society is advancing from the analog era to the digital imaging era, and in line with the trend of this era, various imaging devices such as exploration robots, medical equipment, and CCTV are helping our daily life a lot. However, noises caused by various causes in digital images not only cause image deterioration, but also deteriorate and deteriorate image quality. A typical noise is AWGN, and types of filters to remove it include an average filter, a median filter, and an alpha-trimmed average filter, but these filters have a disadvantage in that they show somewhat inadequate noise reduction performance in the high frequency region. Therefore, in this paper, a modified spatial division average filter based on standard deviation is proposed to effectively reduce AWGN existing in the high frequency region of the image.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1020-1022
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• 2001

because the output of solar cell is direct, it is necessary to install D/A converter system for A.C load, and in case of driving utility line system, it is possible to drive system relation when the system supplies sinusodal current ant voltage having unit power factor. As the characteristics of the soar cell output the is influenced by dailysunight charge, for more electric power it is essential to control the direction toward the san so that the driving point of solar cell can always operate near maximum output point. PWM modulation device among electric power converters must have stable modulation at anytime when it includes noise-factors such as noise-wave and noises on electric voltage wave, a synchronous signal system. In dealing with synchronous signal for control and control signal by microprocessor, it is necessary to compensate it because there is time difference between sample paint and carrier wave. On this papers, single phase PWM current type invertor controled the solar cell having typical voltage dropping character has optimun short current in short, reduces D.C reactance, composes controller for modulation and keeps lower harmonic and high power factor keeping maximum output of solar cell according daily sunlight charge variation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.111-115
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• 2014

Power line communications can be utilized to build up the data transmission network wherever the electricity is available. This type of communication system could provide a basis for the network construction in many application areas which include the smart grid and home networks. On the other hand the power line communication is vulnerable to various types of interferences and noises. Also, its channel characteristics are constantly changing depending on the type and the amount of electrical loads connected to the network. Especially, the usage of DC power supply has been increased due to the explosive expansion of smart devices in our daily lives which result in the increased level of interferences on the power line channel. In this paper, the effect of the operation of the DC power supplies on the channel characteristics and the data transmission performance is analyzed through the experiments.