• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.10
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• pp.72-82
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• 1999

The error diffusion algorithm is excellent for reproducing continuous gray-scale images to bianry images and also has good edge characteristics. However, it is well known that artifacts with objectionable patterns can occur in the halftoned images. On the other hand, a halftone algorithm using blue noise mask has been proposed. where the halftoning is achieved by a pixelwise comparison of gray-scale image with an array, the blue noise mask. It doesn't have pattern artifacts, but the halftoned image looks unclear because the quantization errors are not feedbacked compared to the error diffusion. In this paper, edge enhanced error diffusion which dithers the threshold with the blue noise mask is proposed. We show that the proposed algorithm can produce unstructured and edge enhanced halftone images. This algorithm is analyzed by the concept of an equivalent input image. The performace of the proposed algorithm is compared with that of the conventional halftoning by measuring the radially averaged power spectrum and edge correlation.

• Journal of the Optical Society of Korea
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• v.10 no.2
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• pp.86-90
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• 2006

The external feedback effect on the relative intensity noise (RIN) characteristics of blue InAlGaN laser diode has been analyzed taking into account the spontaneous emission noise and the injection current for the high frequency modulation. A Langevin diffusion model was exploited to characterize its relative intensity noise. The simulation parameters were quantitatively evaluated from the optical gain properties of the InAlGaN multiple quantum well active regions by using the multiband Hamiltonian for the strained wurtzite crystals. The extracted parameters were then applied to the rate equations taking into account the external feedback and the high frequency modulation current. The RIN characteristics were investigated to optimize the low frequency laser diode noise characteristics.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.1
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• pp.7-12
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• 2000

A new speech enhancement algorithm for speech corrupted by slowly varying additive colored noise is suggested based on a state-space signal model. Due to the FIR structure and the unimportance of long-term past information, the receding horizon (RH) FIR filter known to be a best linear unbiased estimation (BLUE) filter is utilized in order to obtain noise-suppressed speech signal. As a special case of the colored noise problem, the suggested approach is generalized to perform the single blind signal separation of two speech signals. It is shown that the exact speech signal is obtained when an incoming speech signal is noise-free.

• Journal of the Korea Safety Management & Science
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• v.7 no.2
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• pp.57-64
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• 2005

Prescribed according to the occupational safety and health low noise measurement method was changed to personal sampling in the method to measure an area noise. Such method had the limit which did not evaluated characteristic of sound of occurrence and the place of origin. This study was peformed to establish an engineering remedy of the work-place noise. The subject was a vibration control process of the place of business in Pusan. A simulation program applied for an engineering improvement of the work-place noise. The results were as follows: 1. An noise occurrence level of the work-place before improvement was $88^{\sim}97dB(A)$, We applied an improvement method to be established and were expected to $80^{\sim}l19dB(A)$, 2. The level of the noise-distribution to appear in the place of origin of the work-place before improvement was $90^{\sim}93dB(A)$ but, We executed the simulation after applied an engineering remedy and predicted $80^{\sim}85dB(A)$. A result of the simulation blue part was changed mostly into the dark blue color. The results suggest that simulation program establishes an engineering remedy and is useful to the case to apply.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.4
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• pp.227-236
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• 2003

This paper proposes a modified jointly-blue noise mask (MJBNM) method using the S-CIELAB color measure as digital color halftoning method. Based on an investigation of the relation between the pattern visibility and the chromatic error, of a blue noise pattern, a halftoning method is proposed that reduces the chromatic error, while preserving a high quality blue noise pattern. Accordingly, to reduce the chrominance error, the low-pass filtered error and S-CIELAB chrominance error are both considered during the mask generation procedure and calculated for single and combined patterns. Using the calculated low-pass filtered error, the patterns are then updated by either adding or removing dots from the multiple binary patterns. Finally, the pattern exhibiting the lower S-CIELAB chrominance error is selected. Experimental results demonstrated that the proposed algorithm can produce a visually pleasing half toned image with a lower chrominance error than the JBNM method.

• Journal of Wellbeing Management and Applied Psychology
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• v.5 no.4
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• pp.19-31
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• 2022

Purpose: This study was conducted to identify indoor air quality in various living spaces using sensors that can measure noise, vibration, fine dust, and odor in real time and to propose optimal indoor air quality maintenance management using Internet of Things(IoT). Research design, data and methodology: Using real-time sensors to monitor physical factors and environmental air pollutants that affect the comfort of the residential environment, Noise, Vibration, Atmospheric Pressure, Blue Light, Formaldehyde, Hydrogen Sulfide, Illumination, Temperature, Ozone, PM10, Aldehyde, Amine, LVOCs and TVOCs were measured. It were measured every 1 seconds from 4 offices and 4 stores on a small scale from November 2018 to January 2019. Results: The difference between illuminance and blue light for each measuring point was found to depend on lighting time, and the ratio of blue light in total illumination was 0.358 ~ 0.393. Formaldehyde and hydrogen sulphide were found to be higher than those that temporarily attract people in an indoor office space that is constantly active, requiring office air ventilation. The noise was found to be 50dB higher than the office WHO recommendation noise level of 35 ~ 40dB. The most important factors for indoor environmental quality were temperature> humidity> illumination> blue light in turn. Conclusions: Various factors that determine the comfort of indoor living space can be measured with real-time sensors. Further, it is judged that the use of IoT can help maintain indoor air quality comfortably.

• Proceedings of the Safety Management and Science Conference
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• 2005.05a
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• pp.273-278
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• 2005

Prescribed according to the occupational safety and health low noise measurement method was changed to personal sampling in the method to measure an area noise. Such method had the limit which did not evaluated characteristic of sound of occurrence and the place of origin. This study was performed to establish an engineering remedy of the work-place noise. The subject was a vibration control process of the place of business in Pusan. A simulation program applied for an engineering improvement of the work-place noise. The results were as follows: 1. An noise occurrence level of the work-place before improvement was $88^{\sim}97dB(A)$, We applied an improvement method to be established and were expected to $80^{\sim}119dB(A)$. 2. The level of the noise-distribution to appear in the place of origin of the work-place before improvement was $90^{\sim}93dB(A)$ but, We executed the simulation after applied an engineering remedy and predicted $80^{\sim}85dB(A)$. A result of the simulation blue part was changed mostly into the dark blue color. The results suggest that simulation program establishes an engineering remedy and is useful to the case to apply.

• Journal of Preventive Medicine and Public Health
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• v.26 no.4 s.44
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• pp.565-573
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• 1993

Noise is not only affecting the ear and the auditory cortex locally, but its influence is widely spread throughout the brain structures, e. g., the reticular formation, the brain stem nuclei or the subcortical forebrain area. Hence, any of the organism's activities can be hindered or stimulated by noise. High noise is a stressor and the catecholamine level can be used both as a stress marker and as an indicator of modified sympathetic nervous system activity. Several recent studies have found that the urinary excretion of catecholamines is increased due to high noise intensity, especially unexpectedly high and long lasting noise. The present study was conducted in order to examine the effects of noise stress on urinary excretion of ctecholamines in rats and humans. Rats were exposed to 90 dB noise for 10, 30, and 60 minutes, 3 and 12 hours. 24 hour . urinary samples were collected and the catecholamones were extracted by alumina and analyzed by HPLC-ECD. Catecholamine levels increased with time of exposure up to 60 minutes : norepinephrine concentration at 60 min of noise=1.038 ng/ml, epinephrine=0.636 ng/ml. Urine catecholamines of blue collar workers exposed to 90 dB of noise at the work place were collected between 2 and 4 p.m. and compared to that of white collar workers exposed to 70 dB. Mean norepinephrine level of the blue collar workers was 0.89 ng/ml (${\pm}0.25$), epinephrine 0.24ng/m1 (${\pm}0.09$), and that of the white collar workers 0.48 ng/ml (${\pm}0.12$), epinephrine 0.19 ng/ml(${\pm}0.05$). It was concluded that noise acts as a stressor and increases the catecholamine levels in both rats and humans.

• ETRI Journal
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• v.34 no.4
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• pp.511-517
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• 2012

The best linear unbiased estimator (BLUE) is most suitable for practical application and can be determined with knowledge of only the first and second moments of the probability density function. Although the BLUE is an existing algorithm, it is still largely unexplored and has not yet been applied to channel estimation in amplify and forward (AF)-based wireless relay networks (WRNs). In this paper, a BLUE-based algorithm is proposed to estimate the overall channel impulse response between the source and destination of AF strategy-based WRNs. Theoretical mean square error (MSE) performance for the BLUE is derived to show the accuracy of the proposed channel estimation algorithm. In addition, the Cram$\acute{e}$r-Rao lower bound (CRLB) is derived to validate the MSE performance. The proposed BLUE channel estimation algorithm approaches the CRLB as the length of the training sequence and number of relays increases. Further, the BLUE performs better than the linear minimum MSE estimator due to the minimum variance characteristic exhibited by the BLUE, which happens to be a function of signal-to-noise ratio.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.377.1-377
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• 2002

Recently, an optical disc system has been proposed using blue laser diode, high NA objective lens and groove only disc structure. A new method is needed to readout CD and DVD in the blue system. In order to readout CD and DVD in HD-DVD system, we adopted dual-lenses actuator in consideration of optical utilization efficiency, optical performance and insurance of sufficient W.D (working distance). (omitted)