• 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.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.232-237
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• 2013

The role of the window length of time-frequency transformation is important for the audio data hiding methods utilizing phase information. In this paper, the experiments for our audio data hiding method were conducted in order to evaluate the audio quality and robustness against reverberant environment. The experimental results showed the tendency that the worse audio quality but better robustness were obtained when the lengthy window was applied. The important reason for quality degradation was pre-echo which flatters the percussive sound. The results also indicated that the wireless communication theory related to the length of time-frequency transform can be applied in the field of audio data hiding and acoustic data transmission.

• International journal of advanced smart convergence
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• v.5 no.4
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• pp.15-20
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• 2016

When a virtual sound source for 3D auditory system is reproduced by a linear loudspeaker array, listeners can perceive not only the direction of the source, but also its distance. Control over perceived distance has often been implemented via the adjustment of various acoustic parameters, such as loudness, spectrum change, and the direct-to-reverberant energy ratio; however, there is a neglected yet powerful cue to the distance of a nearby virtual sound source that can be manipulated for sources that are positioned away from the listener's median plane. This paper address the problem of generating binaural signals for moving sources in closed or in open environments. The proposed perceptual enhancement algorithm composed of three main parts is developed: propagation, reverberation and the effect of the head, torso and pinna. For propagation the effect of attenuation due to distance and molecular air-absorption is considered. Related to the interaction of sounds with the environment, especially in closed environments is reverberation. The effects of the head, torso and pinna on signals that arrive at the listener are also objectives of the consideration. The set of HRTF that have been used to simulate the virtual sound source environment for 3D auditory system. Special attention has been given to the modelling and interpolation of HRTFs for the generation of new transfer functions and definition of trajectories, definition of closed environment, etc. also be considered for their inclusion in the program to achieve realistic binaural renderings. The evaluation is implemented in MATLAB.

• Journal of Intelligence and Information Systems
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• v.14 no.3
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• pp.41-57
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• 2008

U-Publication, the Tag-Embedded publication, is one of U-Media. U-Media is defined as a media where human creates and consumes content through not only human cognitive and perceptual processes but also through the interactions between surrounding digital systems. U-Media provides information by generating, collecting, and attaching the content itself and the related information based on the interaction of the bio-systems incorporating digital information and devices embedded in humans, and surrounding objects including external digital devices. Using U-Publication, readers consume its content not only in offline but also online through a mobile RFID reader which touches and connects the URLs embedded in the RFID tags attached to it. Readers can consume the additional content though the hyperlinks attached to U-Publication and perform commercial activity as well as consumer the printed content. This paper defines the RFID-Tagged publication, proposes its related business models, and evaluates the alternative business models through a simulation study.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.18 no.1
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• pp.44-50
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• 2007

Background and Objectives: The 585-nm pulsed dye laser (PDL) has recently been adopted by otolaryngologists because of its epithelial-sparing properties. Many authors have reported the use of PDL for treatment of various vocal cord lesions. This purpose of this study is to examine the effectiveness of 585-nm PDL in the treatment of vocal polyp. Materials and Methods: Eight patients with vocal polyp were treated with 585-nm PDL from Sep. 2006 to Nov. 2006 in Yong-dong Sevrance hospital. 5 of them went through local anesthesia and 3 of them went through general anesthesia. In order to control laser fiber, flexible digital transnasal laryngoscope was applied under local anesthesia and general anesthesia using LMA, and micromanipulator was used under general anesthesia using endotracheal tube. The evaluations of vocal function was done at pre-and postoperation. Results: All patients improved in the perceptual evaluation of voice after PDL surgery. The aerodynamic study revealed that 5 of 8 patients showed improvement in maximal phonation time, and 6 of 8 showed improvement in mean airflow rate during phonation. The acoustic analysis revealed that all patients showed improvement in Jitter and Shimmer, and 7 of 8 showed improvement in noise to harmony ratio. Conclusion: This study demonstrates promising results in the efficacy of 585-nm PDL for the treatment of vocal polyps, and it illustrates a new option for vocal polyp treatment as well as the advantage of PDL surgery.

• Journal of Korea Multimedia Society
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• v.5 no.4
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• pp.405-414
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• 2002

In this paper, we propose a new objective speech quality measure using noise masking threshold for speech quality assessment of mobile telephone network environments, and verify the effectiveness of the proposed method through the experiments. For such a purpose, well known objective speech quality measures such as BSD and PSQM are first evaluated for digital mobile telephone network environments. However, these conventional methods does not have good performance under mobile networks environments compared to literary results. To be mote effective objective speech quality measure under mobile telephone environments, the proposed method employs human psychoacoustic masking effect. The DMOS, instead of MOS, is used as a subjective speech quality measure for performance evaluation. The performance comparison are carried out with speech data collected from digital mobile telephone environments. As results, the proposed measure have and average 4% higher performance, in terms of correlation, than existing objective speech quality measures such as BSD and PSQM.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.3
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• pp.409-416
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• 2022

This paper relates to the blind noise separation method of time-delayed convolutive mixed signals. Since the mixed model of acoustic signals in a closed space is multi-channel, a convolutive blind signal separation method is applied and time-delayed data samples of the two microphone input signals is used. For signal separation, the mixing coefficient is calculated using an inverse model rather than directly calculating the separation coefficient, and the coefficient update is performed by repeated calculations based on secondary statistical properties to estimate the speech signal. Many simulations were performed to verify the performance of the proposed blind signal separation. As a result of the simulation, noise separation using this method operates safely regardless of convolutive mixing, and PESQ is improved by 0.3 points compared to the general adaptive FIR filter structure.

• Progress in Medical Physics
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• v.19 no.3
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• pp.143-149
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• 2008

The aim of this study is to suggest the method for image enhancement of digital chest radiograph and evaluate clinically the quality of the resultant image. A nonlinear iterative filter was developed in order to reduce quantum noise preserving edge. Dynamic range was adjusted and adaptive image enhancement was performed based on the property of anatomic region and the degree of compatibility with neighboring pixels. The lung fields were enhanced appropriately to visualize effectively vascular tissue, bronchus and lung tissue with the desired mediastinum enhancement. Clinic evaluation was performed by three radiologists with at least 8 years experience. The anatomic regions of 11 in PA and 9 in Lateral were observed carefully in each 100 radiographs according to ITU (International Telecommunication Union) recommendation 500 protocol. The result showed the mean 3.4 between good and adequate. This means that the clinical utility of the image quality is enough. In this study, image enhancement was carried out considering image display device and human perceptual system to prevent the loss of useful anatomic information. In order to increase the diagnostic accuracy in digital radiograph, the continuous study on image enhancement is needed.

• Therapeutic Science for Rehabilitation
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• v.1 no.1
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• pp.29-38
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• 2012

Introduction : This study reviews the main areas of cognitive rehabilitation including executive dysfunction, memory dysfunction, perceptual dysfunction, attention deficit, and dysfunctions in activities of daily living in order to apply to the adaptation of occupational therapy. Body : Cognition programs based on the virtual reality are being used not only to evaluate but to train the overall components of human's cognition. Because the cognitive program is concentrating on the real environment, it is known to bring a remarkable transitional effect to the actual environment, compared to the basic computer-based evaluation and training. Applying virtual reality to the rehabilitation program can develop and advance the high technology and can result in a major effect on the innovative treatment technology. Conclusions : In this process, virtual reality is expected to be researched more in the near future. Particularly in the cognitive realm, it is imperative for researchers to pay attention to the improved transitional effect of the virtual reality toward the actual environment, rather than the already existing method of evaluations. Therefore, application of the virtual reality for the cognitive training should be researched for various types of subjects in the diverse aspects of congnitive function. Application of the virtual reality in the cognitive function has its unlimited potential, thus the rehabilitation program integrated with not only evaluation but training and education is expected extensively in the future.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.191-202
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• 2017

The purpose of this study is to develop an engineer competency model using Analytical Hierarchy Process (AHP) to improve the national technical qualification system. Korea has managed technical human resources at the government level through the operation of a national technical qualification system that certifies engineers with national certificates or technical grades by laws. However, there have been increasing concerns that the government system is separated from global standards and does not reflect an engineer's comprehensive capabilities. For these reasons, the new architecture of the system has been continuously discussed and becomes a major policy issue of the Korean government. For the development of the engineer competency model, domestic and global models were separately structured using 554 valid questionnaires with a consistency ratio (CR) of 0.1 or less. The relative importance of engineer competency factors in a domestic model was career (0.383), qualification (0.253), academic degree (0.195), and job training (0.169) whereas the order in the global model was career (0.308), global ability (0.237), job training (0.175), domestic qualification (0.147), and academic degree (0.134). The results of AHP analysis indicated that the evaluation factors and methods recognized by engineers were different from a current government model focusing on domestic qualifications. There was also perceptual difference in the importance of engineer evaluation factors between groups depending on the type of organizations and markets. This means that it is necessary to reflect the characteristics of organizations and markets when evaluating engineer competency. Based on AHP analysis and literature reviews, this paper discussed how to develop a new engineer competency index (ECI) and presented two effective index models verified by simulation test using 59,721 engineers' information. Lastly, the paper discussed major findings of our empirical research and proposed policy alternatives for the improvement of a national engineer qualification system. The paper contributes to the management of technical human resources since it provides quantitative competency models that are objectively developed by reflecting market recognition and can be effectively used by the policy makers or firms.