• The Journal of the Acoustical Society of Korea
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• v.29 no.7
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• pp.458-467
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• 2010

In this paper, a new audio reproduction system was developed in which the cross-talk signals would be reasonably cancelled at an arbitrary listener position. To adaptively remove the cross-talk signals according to the listener's position, a method of tracking the listener position was employed. This was achieved using the two microphones, where the listener direction was estimated using the time-delay between the two signals from the two microphones, respectively. Moreover, room reverberation effects were taken into consideration where linear prediction analysis was involved. To remove the cross-talk signals at the left-and right-ears, the paths between the sources and the ears were represented using the KEMAR head-related transfer functions (HRTFs) which were measured from the artificial dummy head. To evaluate the usefulness of the proposed listener tracking system, the performance of cross-talk cancellation was evaluated at the estimated listener positions. The performance was evaluated in terms of the channel separation ration (CSR), a -10 dB of CSR was experimentally achieved although the listener positions were more or less deviated. A real-time system was implemented using a floating-point digital signal processor (DSP). It was confirmed that the average errors of the listener direction was 5 degree and the subjects indicated that 80 % of the stimuli was perceived as the correct directions.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.150-157
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• 2009

In this paper, we propose a person tracking based multi-channel audio panning system for multi-view broadcasting services. Multi-view broadcasting is to render the video sequences that are captured from a set of cameras based on different viewpoints, and multi-channel audio panning techniques are necessary for audio rendering in these services. In order to apply such a realistic audio technique to this multi-view broadcasting service, person tracking techniques which are to estimate the position of users are also necessary. For these reasons, proposed methods are composed of two parts. The first part is a person tracking method by using ultrasonic satellites and receiver. We could obtain user's coordinates of high resolution and short duration about 10 mm and 150 ms. The second part is MPEG Surround parameter-based multi-channel audio panning method. It is a method to obtain panned multi-channel audio by controlling the MPEG Surround spatial parameters. A MUSHRA test is conducted to objectively evaluate the perceptual quality and measure localization performance using a dummy head. From the experiments, it is shown that the proposed method provides better perceptual quality and localization performance than the conventional parameter-based audio panning method. In addition, we implement the prototype of person tracking based multi-view broadcasting system by integrating proposed methods with multi-view display system.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.1
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• pp.17-25
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• 2012

Purpose: Recently, a three dimensional approach to hard and soft tissues of the maxillofacial area has been widely used. This study was to evaluate the reproducibility and accuracy of a stereocamera compared to actual measurement methods using a digital caliper and digitizer. Methods: The stereoscopies of 7 head dummies with different sizes and shapes were obtained using a Di3D system (Dimensional Imaging, Glasgow, UK) after marking reference points on facial areas. From the obtained stereoscopy, 10 measurements representing the width, height and depth of each of the facial sections of the dummy were measured twice using a three dimensional reverse engineering software program (RapidForm$^{TM}$ 2006, Inus, Seoul, Korea). The x, y, and z coordinates of each of the three dimensional measurements were obtained and distances between two points were calculated. All procedures were repeated twice. The actual measurement method was performed twice, directly on dummies, using a digital caliper and values were compared with the previously determined values. Results: The results were as follows. In the ANOVA analysis, there were no significant statistical differences among the three measurement methods. In the Bonferroni analysis, with adjustments applied for multiple comparisons, there was no difference between actual measurement methods using a digitizer and a digital caliper. However, there was some difference between using a stereocamera and actual measurement methods using a digitizer and a digital caliper in values of $Ex_{Rt}-Ex_{Lt}$, $En_{Rt}-En_{Lt}$, $Ala_{Rt}-Ala_{Lt}$, $Ch_{Rt}-Ch_{Lt}$, G-Pg', $Ala_{Rt}$-Prn, $Ala_{Rt}$-Prn. The mean value for technical error in measurement (TEM) in Di3D (0.98 mm) was slightly higher than for a digital caliper (0.17 mm) and a digitizer (0.30 mm). In an intraclass correlation coefficient (ICC) there were no significant differences among the three measurement methods, but the Di3D system with the stereocamera showed relatively lower reproducibility compared to actual measurement methods using a digitizer and a digital caliper. Conclusion: These results indicate that some complementary measures may be needed to improve accuracy and reproducibility in the Di3D system with stereocamera.

• Journal of radiological science and technology
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• v.45 no.4
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• pp.299-304
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• 2022

This study uses the 'S-align' function to present a reference value of the X-ray tube angle for the realization of an image similar to that of the chest PA image during chest AP radiography. This study targeted dummy phantom and used a 17"×17" DR image receptor. The irradiation conditions were 110 kVp, 160 mA, 50 ms, and the distance between the central X-ray and the image receptor was set to 180 cm and 110 cm, respectively. The end of the catheter was placed at the 11th thoracic height to indicate the nasogastric tube. In the case of lung apex length measurement, the mean value of measurement was 30.53±0.47 in PA. T 0°, TCA 5~25°, TCE 5~15° were 21.07±0.29, 27.60±0.21, 34.13±0.44, 39.86±0.31, 45.96±0.61 mm, 54.13±0.37 mm, 16.16±0.46 mm, 9.81±0.35 mm, 2.75±0.30 mm, respectively. For the depth of the catheter end, the average value measured at PA was 6.70±0.31 mm. T 0°, TCA 5~25°, TCE 5~15° were 15.72±0.38 mm, 24.10±0.50 mm, 29.24±0.86 mm, 34.35±0.35 mm, 41.06±1.08 mm, 48.07±0.38 mm, 12.85±0.25 mm, 7.92±0.36 mm, 3.01±0.39 mm, respectively. The length of the lung apex was similar to that of chest PA when the angle of incidence was adjusted from 5° to 10° in the leg direction, and the depth of the catheter tip was most similar when the X-ray tube angle was incident at 10° in the head direction. Therefore, To change the X-ray tube angle according to the purpose of the examination during the chest AP radiography using 'S-align' function is considered necessary.

• Journal of Nutrition and Health
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• v.57 no.1
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• pp.153-169
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• 2024

Purpose: The main goal of this study was to identify the impact of coronavirus disease 2019 (COVID-19) on grocery purchases (i.e., fresh and processed foods by grain, vegetable, fruit, seafood, and meat categories) in Korea. To understand the specific impact of COVID-19, the study period was divided into 3 segments: PRE-COVID-19, INTER-COVID-19, and POST-COVID-19. Methods: We used the microdata of household income and expenditure from Statistics Korea (KOSTAT), representing households across the country. The data comprised monthly grocery expenditure data from January 2019 to September 2022. First, we compared the PRE-COVID-19 period to INTER-COVID-19 and then INTER-COVID-19 to POST-COVID-19 and used multiple regression analysis. The covariates used were the gender and age of the head of the household, the household's monthly income, the number of family members, the price index, and the month (dummy variable). Results: The expenditures on all grocery categories except fresh fruit increased from PRE-COVID-19 to INTER-COVID-19. From INTER-COVID-19 to POST-COVID-19, almost all grocery category spending declined, with processed meat being the only exception. Most purchases of protein sources, increased during INTER-COVID-19 compared to PRE-COVID-19, while ham/sausage/bacon for meat protein, fish cakes and canned seafood for seafood protein, and soy milk for plant-based protein did not decrease during POST-COVID-19 compared to INTER-COVID-19. Conclusion: These results show an overall increase in in-home grocery expenditure during COVID-19 due to an increase in eating at home, followed by a decrease in this expenditure in the POST-COVID-19 period. Among the trends, the protein and highly processed convenience food categories did not see a decline in spending during the POST-COVID-19 period, which is a reflection of the preferences of consumers in the post-COVID-19 period.