• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.11
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• pp.918-926
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• 2012

In 3D video transmission, a depth map being used for depth image based rendering (DIBR) is generally compressed by reducing resolution for coding efficiency. Errors in resolution reduction are recovered by an appropriate up-sampling method after decoding. However, most previous works only focus on up-sampling techniques to reduce errors. In this paper, we propose a novel down-sampling technique of depth map that applies different down-sampling rates on moving objects and background in order to enhance human perceptual quality. Experimental results demonstrate that the proposed scheme provides both higher visual quality and peak signal-to-noise ratio (PSNR). Also, our method is compatible with other up-sampling techniques.

• The Journal of Korean Society for School & Community Health Education
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• v.9 no.2
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• pp.81-90
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• 2008

Objectives: Since 80% of the information we get from the environment comes in through our eyes (Anshel JR, 1999), uncorrected visual problems negatively affect children's educational process and perceptual development. The objectives of this study were: 1st, to document the prevalence of learning related vision problem in primary school children. 2nd, to compare responses of children with those of parents on visual symptoms. Lastly, to determine if there is an association between visual symptoms and academic performance. Methods: We administered visual-symptom quality of life questionnaire developed by Oklahoma College of Optometry in Vision Development to 1031 primary school children and their parent. Visual symptoms responded by children and their parents were compared using Independent Sample t-test and the relation between visual symptoms and academic performance were calculated using Pearson Correlation tests. Results and Conclusions: The number of children who need further professional evaluation, that is visual-symptom scores were ${\geq}20$, reported by children(25%) was greater than that reported by parents(16%). And visual-symptom scores reported by children were significantly higher than those reported by parents in every grade(p<0.01, p<0.001). Visual symptoms reported by both children and parents were found to be inversely correlated to academic performance in every academic area and most of their correlations were statistically significant(p<0.05). Therefore, children with more visual-symptom reported by both group had negative effects on children's academic performance.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.4
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• pp.121-130
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• 2004

In the application requiring the interoperability of different networks such as VoIP and wireless communication system, two speech codecs must work together with the structure of cascaded connection, tandem. Tandem has several problems such as long delay, high complexity and quality degradation due to twice complete encoding/decoding process. Transcoding is one of the best solutions to solve these problems. Transcoding algorithm is varied with the structure of source and target coder. In this paper, transcoding algorithm including the LSP conversion, the pitch estimation and new perceptual weighting filter for reducing complexity and improving qualify is proposed. These algorithms are applied to the pair of AMR md G.723.1. By employing the proposed algorithms in the transcoder, the complexity is reduced by about 20%-58% and quality is improved compared to tandem.

• The Journal of the Acoustical Society of Korea
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• v.39 no.2
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• pp.113-119
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• 2020

Motor noise is a major concern in order to improve perceptual feeling of car interior sound due to increased motor usage in passenger cars. The purpose of this study is to propose factors that can represent the acoustic performance of motor noise according to the change of load. To this end, at first, it is shown that power spectrum and total loudness are not fit for noise performance, and then, PN_B, partial loudness related to the brush friction component, and PN_R, partial loudness related to the torque ripple component are investigated as factors representing motor noise. The performance curve of motor noise using PN_B and PN_R is proposed to identify trends of motor noise according to the loads. The curve could be a guide for the noise control, the selection of motor, and the improvement of a system.

• The Journal of the Acoustical Society of Korea
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• v.19 no.4
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• pp.58-68
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• 2000

This paper proposes a sinusoidal modeling of polyphonic audio signals. Sinusoidal modeling which has been applied well to speech and monophonic signals cannot be applied directly to polyphonic signals because a window size for sinusoidal analysis cannot be determined over the entire signal. In addition, for high quality synthesized signal transient parts like attacks should be preserved which determines timbre of musical instrument. In this paper, a multiresolution filter bank is designed which splits the input signal into six octave-spaced subbands without aliasing and sinusoidal modeling is applied to each subband signal. To alleviate smearing of transients in sinusoidal modeling a dynamic segmentation method is applied to subbands which determines the analysis-synthesis frame size adaptively to fit time-frequency characteristics of the subband signal. The improved dynamic segmentation is proposed which shows better performance about transients and reduced computation. For various polyphonic audio signals the result of simulation shows the suggested sinusoidal modeling can model polyphonic audio signals without loss of perceptual quality.

• The KIPS Transactions:PartD
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• v.17D no.6
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• pp.471-480
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• 2010

The purpose of this study is to explore determinants which affect the significant increase in the user acceptance of smart phone. This study also analyzes the effect of each variable on the actual acceptance by empirical methods. In this study, first, the system quality and the service quality are defined as independent variables based on developed IS success model of DeLone & McLean(2003). Second, we proposed the research model by providing trust and perceptual immersion as intermediate variables, and user satisfaction and actual use as dependent variables by the proceeding research for accepting information technology and new service. Third, the statistical analysis is conducted by surveying to 200 smart phone users for verifying a validity of research models and hypotheses. As a result, almost hypotheses are accepted in confidence interval except for the hypothesis between security and trust variable.

• Phonetics and Speech Sciences
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• v.10 no.4
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• pp.147-154
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• 2018

Wet voice quality (WVQ) is a characteristic that appears after swallowing. Although the concept is accepted by many clinicians worldwide, it is nevertheless ambiguous. In this study, we investigated WVQ in patients with swallowing disorders using acoustic analysis. A total of 106 patients diagnosed with penetration-aspiration by the videofluoroscopic swallowing study (VFSS) were recruited. A voice recording of vowel /a/ was conducted before and after the VFSS, and an acoustic analysis was then performed using PRAAT. Voice after VFSS was used for a perceptual judgment and divided into two groups: the Wet group (48 patients) and the Non-wet group (58 patients). At the post-VFSS stage, the two groups displayed significant differences in many acoustic parameters including F0_SD, Jitter, RAP, Shimmer, APQ, HNR, NHR, FUF, DVB, and CPP. The parameter affecting judging wetness resulted into Jitter and NHR by the logistic regression test. At the pre-VFSS stage, the two groups differed significantly in many acoustic parameters including Intensity, Jitter, RAP, Shimmer, NHR, FUF, DVB, and CPP. Both pre-and post-VFSS, the mean values of all significant parameters, except Intensity, HNR, and CPP, were higher in the Wet group. According to pre-and post-VFSS, the two groups displayed interactions in many parameters (Intensity, F0_SD, Jitter, RAP, Shimmer, APQ, HNR, NHR, FUF, DVB, and CPP). In particular, Intensity increased in both groups after the VFSS, although the increase in the Non-wet group was greater. Based on these results, it was conjectured that the WVQ after swallowing resulted from the secretion effect of the mucous membrane due to the dry laryngeal characteristic of elderly patients, rather than aspiration resulting in food on the vocal cords.

• Phonetics and Speech Sciences
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• v.10 no.4
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• pp.155-161
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• 2018

The purpose of this study was to evaluate the efficacy of a multiple voice therapy technique ($SKMVTT^{(R)}$) using laughter for the treatment of various benign vocal fold lesions. To achieve this, 23 female patients diagnosed with vocal nodules, vocal polyp, and muscle tension dysphonia through videostroboscopy were enrolled in vocal hygiene and $SKMVTT^{(R)}$. All of the patients were treated once a week for 4 to 12 sessions. The GRBAS scale was used to confirm the changes in voice quality before and after the treatment. Acoustic analysis was performed to evaluate jitter, shimmer, NHR, fundamental frequency variation, amplitude variation, PFR, and dB range. Videostroboscopy was performed to confirm the changes in the laryngeal features before and after the treatment. After the $SKMVTT^{(R)}$, the results of the perceptual evaluation demonstrated that the G, R, and B scales significantly improved. An acoustic evaluation also demonstrated that jitter, shimmer, NHR, vAm, vFo, PFR, and dB range also significantly improved after the $SKMVTT^{(R)}$. In comparison to the videostroboscopic findings, the size of the vocal nodules and vocal polyp decreased or disappeared after the treatment. In addition, the size of the cuneiform tubercles decreased, the length of the aryepiglottic folds became longer, and the laryngeal findings of the supraglottic compressions improved after the $SKMVTT^{(R)}$. These results suggest that the $SKMVTT^{(R)}$ is effective in improving the vocal quality of patients with benign vocal fold lesions. In conclusion, it seems that laughter and inspiratory phonation suppressed abnormal laryngeal elevation and lowered laryngeal height, which seems to have the effect of improving hyperfunctional phonation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5229-5237
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• 2012

Occupational therapist is required for patient-centered approaches to actively seek the perspectives of patients and their families in clinical settings. The purpose of this study was to investigate the current trends and to suggest future-oriented view of examination and assessment used by neurological occupational therapist in clinical settings. Sixty-six occupational therapists who work in persons with neurological disorders participated in this study. The survey was measured from Seoul and GyeongGi by means of E-mail about commonly used assessment tools and selecting considerations. The participants were 66 neurological occupational therapists. The number of patients by one day was from 10 to 14 persons, and the length of time for initial evaluation was 20-40 minutes per one patient, and reexamination periods was every 1 month or as functional changes were detected. The using tool was not limited only neurological tools, and choice consideration was the reliability and validity of clinical measures. The most frequently used tools for adults were: JHFT for motor function in upper extremity, MMSE-K for cognitive perceptual assessment, MBI for daily activity assessment, and COPM for occupational performance. The most frequently used tools for child were: MVPT for cognitive perceptual assessment and Wee-FIM for daily activity assessment. The results of this study suggest that it is necessary to integrate and associate patient-report, care-giver report, and results of performance-based assessment for estimating plan of care more quality.

• The Journal of the Acoustical Society of Korea
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• v.25 no.8
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• pp.383-388
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• 2006

This Paper presents a novel approach to single channel microphone speech enhancement in noisy environments. Widely used noise reduction techniques based on the spectral subtraction are generally expressed as a spectral gam depending on the signal-to-noise ratio (SNR). The well-known decision-directed(DD) estimator of Ephraim and Malah efficiently reduces musical noise under the background noise conditions, but generates the delay of the a prioiri SNR because the DD weights the speech spectrum component of the Previous frame in the speech signal. Therefore, the noise suppression gain which is affected by the delay of the a priori SNR, which is estimated by the DD matches the previous frame rather than the current one, so after noise suppression. this degrades the noise reduction performance during speech transient periods. We propose a computationally simple but effective speech enhancement technique based on the sigmoid type function for the weight Parameter of the DD. The proposed approach solves the delay problem about the main parameter, the a priori SNR of the DD while maintaining the benefits of the DD. Performances of the proposed enhancement algorithm are evaluated by ITU-T p.862 Perceptual Evaluation of Speech duality (PESQ). the Mean Opinion Score (MOS) and the speech spectrogram under various noise environments and yields better results compared with the fixed weight parameter of the DD.