• The Journal of the Acoustical Society of Korea
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• v.32 no.4
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• pp.294-300
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• 2013

In this paper, we present performance analysis results of parametric array communication system in terms of theoretical BER and channel capacity of MIMO in underwater AWGN channel by using simplified SNR of difference frequency. The SNR of the difference frequency is calculated by using transmission loss, noise level, and source level of difference frequency in which nonlinear effect is considered. By assuming primary frequencies as 210 kHz and 190 kHz, difference frequency as 20 kHz, transducer diameter as 0.1 m, and noise level as 50 dB and the requested BER as $10^{-4}$, we obtain parametric array communication range gains over the communication system using primary frequency of 59.11 km in fresh water and 5 km in sea water, respectively. Also we obtain range gains of 38.84 km and 46.38 km in fresh water, and 3.88 km and 4.38 km in sea water when we use SISO and $2{\times}2$ MIMO parametric array communications for the channel capacity of 10 bps/Hz.

• Journal of the Korea Convergence Society
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• v.8 no.1
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• pp.1-6
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• 2017

In this paper, we propose a new method for a correlative phase comparison direction finding(DF) which detects the arrival direction of radio waves by data fusing the calculated phase difference and the measured phase difference between the antennas when the radio waves are incident on the circular array antenna composed of 7 antennas respectively. The correlation type phase comparison method uses a uniform circular array(UCA) and a linear array method. The phase difference data calculated formally and the phase difference data measured in the test environment are fused with a correlation function, therefore, it is superior to the currently used phase comparison direction detection method. When the signal-to-noise ratio (SNR) of the received signal is 20dB and the inter-antenna distance to the wavelength of the received signal($L/{\lambda}$) is 0.5, the accuracy of the correlative DF is $1.7^{\circ}$ while measurement phase comparison's is larger than $2.5^{\circ}$, It can be used for electromagnetic signal monitoring and military direction detection.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6C
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• pp.465-474
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• 2005

In this paper, a directional reconstruction of lost block in image over noisy channel is presented. DCT coefficients or pixel values in the lost blocks are recovered by using the linear interpolation with available neighboring blocks that are adaptively selected by the directional measure that are composed of the DDC (Difference of DC opposite blocks)and SAC(Similarity of AC opposite blocks) between opposite blocks around lost blocks. The proposed directional recovery method is effective for the strong edge and texture regions because we do not make use of the fixed 4-neighboring blocks but exploit the varying neighboring blocks adaptively by the directional information in the local image. In this paper, we describe the novel directional measure(CDS: Combination of DDC and SAC) composed of the DDC and the SAC and select the usable block to recover the lost block with the directional measure. The proposed method shows about 0.6dB PSNR improvement in average compared to the conventional methods.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.449-454
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• 2020

We propose an improved de-interlacing method that converts the interlaced images into the progressive images by one field. In the first, Inter-pixel values are calculated by applying Newton's forward difference, backward difference interpolation from upper and lower 5 pixel values. Using inter-pixel values obtained from upper and lower 5 pixel values, it makes more accurate a direction estimate by applying the correlation between upper and lower pixel. If an edge direction is determined from the correlation, a missing pixel value is calculated into the average of upper and lower pixel obtained from predicted direction of edge. From simulation results, it is shown that the proposed method improves subjective image quality at edge region and objective image quality at 0.2~0.3dB as quantitative calculation result of PSNR, compared to previous various de-interlacing methods.

• Journal of Environmental Health Sciences
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• v.17 no.2
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• pp.67-77
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• 1991

The purpose of this study was to investigate the psychosomatic health status of printers. The 77 printers and 24 control group were analysed about salary, drinking, smoking, education, sex, marriage, age and working age by the THI (Todai Health Index) questionaire. THI was modified from CMI(Cornell Medical Index) and developed by Tokyo University Research Team in Japan. The resuts obtained were summarized as follows. 1. The printers, who get more salary showed high score about mental conplaints, especially, mental irritability(j), nervusness (E), lie Scale(L), aggressiveness(F) and irregualr life(G) and lower salary showed generally high score about physical complaints, especially, mouth and anus (D), digestive symptom(C) multiple subjective symptom(I). 2. According to the printers drinking amount shows the difference, eg nondrinker scored higher on mouth and anus(D), 90mg/week drinker scored higher on multiple subjective symptom(I), digestive symptom(C), depression(K), nervousness(E), and irregular life(G), 91~179mg/week drinker scored higher on impulsiveness(H), mental irritability(J), 270~359mg/week drinker scored higher on respiratory(A), lie scale (L) and aggressiveness (F). 3. The nonsmoker scored high level on mouth and anus(D), mental irritability(J). The previous smoker scored on multiple symptom(I), eyes and skin(B), digestive(C), lie scale(L), and depression(K). The present smoker scored on respiratory(A), impulsivehess(H), aggressiveness(F), nervousness(E), and irregular life(G). 4. According to the printers working age showed almost high score about subjective symptoms on 1~3 year. 5. Men printers high scored on respiratory(A). lie scale(L), aggressiveness(F), women printers scored about mental complaints, especially, impulsiveness(H), mental irritability(J), depression (K), nervousness (E). 6. According to the printers age showed high scored about, below 20 years were lie scale(L). aggressiveness(F), irregular life(G) 21~30years were multiple subjective symptom(I) respiratory (A), eyes and skin(B), mouth and anus(D), impulsiveness(H), mental irritability(J), depression (K), nervousness(E), and over 41 years were digestive(C). 7. Married printers scored high level on eyes and skin(B), digestive(C) and impulsivehess(H), and single printers on respiratory(A), mouth and anus(D), lie scale(L), mental irritability(J). 8. According to education shows the difference, eg high school scored higher on eyes and skin (B), mental irritability(J), depression(K), nervousness(E), collage and over scored higher on multiple subjective symptom(I ), respiratory (A), mouth and anus (D), lie scale (L), aggressiveness (F), irregular life (G), and middle school scored high on digestive (C), impulsiveness (H).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.408-416
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• 2010

A study on the calibration of an X-band HPS(Hongik Polarimetric Scatterometer) system for ground-based operation is presented in this paper. In order to calibrate the scatterometer system, the degree of its distortions are analyzed by comparison between theoretical- and measured-values using the theoretically well-known calibration targets such as a metal sphere, a trihedral corner reflector(CR) and a metal cylinder. The calibration works in the field conditions depend on the precise and stable measurements of those calibration target. we present a measurement technique, so-called, an automatic 2-D target-scanning technique, using the incidence-angle(${\xi}-$ and ${\phi}-$ directions) control of HPS system. Then, we used STCT(Single-Target Calibration Technique) and GCT(General Calibration Technique) to calibrate a distortion of the scatterometer system, and measured the polarimetric RCS(Radar Cross Section) and phase-difference of a trihedral-CR as a test-target to verify the accuracy of the calibration technique. Then, three different types(i.e., 10, 20, 30 cm) of trihedral-CR were used. we obtained the error ranges about ${\pm}1.0$dB, ${\pm}0.5$ dB in a polarimetric RCS and about $-20^{\circ}{\sim}0^{\circ}$ and ${\pm}5^{\circ}$ in the co-polarized phase-difference by using the GCT and STCT, respectively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.8 s.101
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• pp.904-910
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• 2005

A 7-point verbal noise annoyance scale for residential noises was developed in this study. An auditory experiment using major residential noises such as air-borne, bathroom drainage, and traffic noises was conducted to develop a noise annoyance scale for rating residential noises and allowable limit of them. The modifiers used in the scales were selected according to the method proposed by ICBEN(international commission on the biological effect of noise) Team 6. Results showed that the intensity of the selected words in the 7-point noise annoyance scale was highly correlated with noise levels. and that the intensity difference between each pair of successive levels in the 7-point annoyance scale was almost identical. The allowable limit of residential noise was also investigated in the auditory experiment and that of airborne, drainage and traffic noises were 42.3 dB(A), 41.0 dB(A) and 42.7 dB(A), respectively.

• Journal of KSNVE
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• v.7 no.1
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• pp.117-125
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• 1997

The aim of this research is to measure the damage caused by the vibrations of passing trains. In order to determine the vibration levels of the trains, twelve points along the Honam, Cholla and Kyungjun lines were chose. There are two goals to be achieved from the data gathered. The first is to determine whether or not the trains are operating under governmentally determined levels. The second goal is to establish countermeasure in order to minimize the effects of the vibrations on the people who live near the train lines. A vibration level meter was used to measure the vibration levels at all twelve points at times when no trains were travelling and at times when trains were travelling. As a result, it was found that Saemaeulho and Mugunghwaho, had a higher vibration level of 2 - 3 dB than Pidulgiho and freight trans. There were no relationship between speed and vibration level. The vibration levels did change according to capacity and size of the engine. In such cases there was a difference of 2 - 7 dB. Where vibration proof ditches were in place, the vibration level were decreased by 3 - 6 dB. The practical decreases in vibration levels was similar to the theoretical decreases.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.173-181
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• 2002

Generally the one of serious problems in Voice Activity Detection (VAD) is speech region detection in noise environment. Therefore, this paper propose the new method using energy, lsp varation. As a result of processing time and speech quality of the proposed algorithm, the processing time is reduced due to the accurate detection of inactive period, and there is almot no difference in the subjective quality test. As a result of bit rate, proposed algorithm measures the number of VAD=1 and the result shows predominant reduction of bit rate as SNR of noisy speech is low (about 5∼10 dB).

• KIEAE Journal
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• v.15 no.2
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• pp.61-67
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• 2015

Purpose: The balcony in the apartment is important space not only as a fire escape but also as a buffer for heat and sound insulation. However, with the legalization of balcony expansion for residential apartments in Korea in 2006, many households have eliminated the balcony space altogether to increase the inner space, often without sufficient consideration for the effects on the indoor environment. This study examined the sound insulation performance of exterior-facing windows in enclosed balconies and the changes in the indoor acoustic environment due to expansion to provide a basis for appropriate balcony expansion. The apartments for the field test were chosen where two balcony types can be compared, and the sound insulation performance for the eighteen balcony windows was measured. The windows installed were typical double window with thickness 16 mm or 22 mm. Measurements of the weighted standard sound pressure level difference showed a decrease of about 3 dB in sound insulation performance due to expansion. For common exterior noise levels of 70-85 dB(A), the indoor noise level can exceed 45 dB(A), the limit level regulated in Korea. However, it was found that the sound insulation performance of the window and the quality of the construction have more influence on indoor noise levels than balcony expansion itself.