• 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.

• The Journal of the Acoustical Society of Korea
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• v.28 no.2
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• pp.96-106
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• 2009

In this paper, correlation between the headphone's acoustical characteristics and the subjective preferences is analyzed, and a possibility of predicting the subjective preferences using the acoustical characteristics is investigated, The headphone's acoustical characteristics include the total harmonic distortions, the variation of the frequency response which were measured by separate channel and the inter-aural correlation coefficients, Those characteristics were measured in a noise-free anechoic chamber, using a head and torso simulator, The subjective preferences were scored in terms of loudness, clearness, spaciousness, fullness and overall impression, In the subjective listening test, 12 subjects were participated who have plentiful listening experiences, The programs include 5 kinds of musics; korean popular song, pop song, light music, male-voice and classic, The 8 models of the headphones were employed, including 4 closed-type circumaural headphones, 2 open-type supraaural headphones and 2 intra-concha headphones, A significant test was carred on the results from the subjective test, using a two-way ANOVA test, The correlation coefficients between the acoustical parameters and the subjective preferences were computed, Experimental results showed that the variation of the magnitude of frequency response measured from a right channel revealed higher correlation with the subjective preferences. Whereas the inter-aural correlation coefficients have very low correlation coefficients.

• The Journal of the Acoustical Society of Korea
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• v.27 no.7
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• pp.333-341
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• 2008

In this paper, a new interpolation model for the head related transfer function (HRTF) was proposed. In the method herein, we assume that the impulse response of the HRTF for each azimuth angle is given by linear interpolation of the time-delayed neighboring impulse responses of HRTFs. The time delay of the HRTF for each azimuth angle is given by sum of the sound wave propagation time from the ears to the sound source, which can be estimated by using azimuth angle, the physical shape of the underlying head and the distance between the head and sound source, and the refinement time yielding the minimum mean square error. Moreover, in the proposed model, the interpolation intervals were not fixed but varied, which were determined by minimizing the total number of HRTFs while the synthesized signals have no perceptual difference from the original signals in terms of sound location. To validate the usefulness of the proposed interpolation model, the proposed model was applied to the several HRTFs that were obtained from one dummy-head and three human heads. We used the HRTFs that have 5 degree azimuth angle resolution at 0 degree elevation (horizontal plane). The experimental results showed that using only $30\sim40%$ of the original HRTFs were sufficient for producing the signals that have no audible differences from the original ones in terms of sound location.

• Journal of Broadcast Engineering
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• v.26 no.4
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• pp.453-462
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• 2021

A lot of license plate data is required for car number recognition. License plate data needs to be balanced from past license plates to the latest license plates. However, it is difficult to obtain data from the actual past license plate to the latest ones. In order to solve this problem, a license plate recognition study through deep learning is being conducted by creating a synthetic license plates. Since the synthetic data have differences from real data, and various data augmentation techniques are used to solve these problems. Existing data augmentation simply used methods such as brightness, rotation, affine transformation, blur, and noise. In this paper, we apply a style transformation method that transforms synthetic data into real-world data styles with data augmentation methods. In addition, real license plate data are noisy when it is captured from a distance and under the dark environment. If we simply recognize characters with input data, chances of misrecognition are high. To improve character recognition, in this paper, we applied the DeblurGANv2 method as a quality improvement method for character recognition, increasing the accuracy of license plate recognition. The method of deep learning for license plate detection and license plate number recognition used YOLO-V5. To determine the performance of the synthetic license plate data, we construct a test set by collecting our own secured license plates. License plate detection without style conversion recorded 0.614 mAP. As a result of applying the style transformation, we confirm that the license plate detection performance was improved by recording 0.679mAP. In addition, the successul detection rate without image enhancement was 0.872, and the detection rate was 0.915 after image enhancement, confirming that the performance improved.

• International journal of advanced smart convergence
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• v.6 no.2
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• pp.59-64
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• 2017

There are three sorts of voices of female vocalists: soprano, mezzo-soprano, and contralto according to the transliteration. Among them, the soprano has the highest vocal range. Since the voice is generated through the human vocal tract based on the voice generation model, it is greatly influenced by the vocal tract. The structure of vocal organs differs from person to person, and the formants characteristic of vocalization differ accordingly. The formant characteristic refers to a characteristic in which a specific frequency band appears distinctly due to resonance occurring in each vocal tract in the vocal process. Formant characteristics include personality that occurs in the throat, jaw, lips, and teeth, as well as phonological properties of phonemes. The first formant is the throat, the second formant is the jaw, the third formant and the fourth formant are caused by the resonance phenomenon in the lips and the teeth. Among them, pronunciation is influenced not only by phonological information but also by jaws, lips and teeth. When the mouth is small or the jaw is stiff when pronouncing, pronunciation becomes unclear. Therefore, the higher the accuracy of the pronunciation characteristics, the more clearly the formant characteristics appear in the grammar spectrum. However, many soprano singers can not open their mouths because their jaws, lips, teeth, and facial muscles are rigid to maintain high tones when singing, which makes the pronunciation unclear and thus the formant characteristics become unclear. In this paper, in order to confirm the accuracy of the pronunciation characteristics of soprano singers, the experimental group was selected as the soprano singers A, B, C, D, E of Korea and analyzed the grammar spectrum and conducted the MOS test for pronunciation recognition. As a result, soprano singer B showed a clear recognition from F1 to F5 and MOS test result showed the highest recognition rate with 4.6 points. Soprano singers A, C, and D appear from F1 to F3, but it was difficult to find formants above 2kHz. Finally, the soprano singer E had difficulty in finding the formant as a whole, and MOS test showed the lowest recognition rate at 2.1 points. Therefore, we confirmed that the soprano singer B, which exhibits the most distinct formant characteristics in the grammar spectrum, has the best pronunciation accuracy.

• Korean journal of communication and information
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• v.79
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• pp.140-164
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• 2016

What is an appropriate length of an article in the mobile era producing new tastes of contents combining computing and mobile communication? Is it still valid to have a lengthy article as high level journalism even in the mobile era? Is there any possibility to have a short article combination to give us readability and the amount of information? This study aims to find some answers to these questions. The length of articles were controlled with a field experiment; from an article of 346 syllables(including spaces between syllables) which does not need finger scrolling on a mobile phone to articles of 633, 1033, 1368 syllables(including spaces between syllables) which frequently appear in newspapers and broadcasting news program. All the main themes were same for 4 articles which have different length. Three hundred and eighty four students viewed one of the 4 articles through mobile phone or newspaper. Each participant checked their preference and evaluated quality on the article, were asked to recall contents of the article. In newspaper group, articles with 346 or 1033 syllables were highly evaluated. Mobile group seemed to prefer articles of 346 or 633 syllables. In conclusion, we need to consider various strategies shortening the length of an article into 346 or 633 syllables as a basic format to meet the neEds of mobile era.

• Korean journal of communication and information
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• v.79
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• pp.7-39
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• 2016

Journalism and Mass Communication as an academic field is believed more politicized one than pure literature and natural science. With the growth of the media, there follows additional opportunities for media scholars to take a part in politics as well. Few attention was given to understand the status and mechanism of political intervention either as advisers or decision makers though. This study attempts thus to fill this vacuum. For this, first of all, it examines a various types of laws related to media politics. Total number of 164 scholars who participated in 12 councils and commissions were analyzed on the following step. Research shows that there are patterns which favor Seoul National University, U.S. trained Ph. D and geographic preference to the capital. Neither academic excellence nor commitment to public interest appear to have impact on taking those positions. Taking into account media's expansion into politics, it is inevitable for media scholars to take responsibility not only in policy making but in taking leadership. Accordingly, the question of necessity is not who but how as much as manner. The authors hope this study will be a valuable opportunity to establish a kind of ethical standards in media politics.

• Journal of Internet Computing and Services
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• v.12 no.4
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• pp.61-71
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• 2011

The Smart Network Project is planned for achieving the Internet advanced country by adjusting the Government Future Internet Development as a national agenda. The future Internet is defined as diverse alternative technology and services that can provide optimal services for individual characteristic and situation in anywhere, anytime throughout convergence of communication, broadcasting, and computing to solve the current limitation of the Internet. This paper is to analyze the economic effects of the smart network build-up. For the economic effect analysis, we reclassified the smart network industry classification system and re-drew up 2011 Inter-industry Relations Table by using the Inter-industry Relations Table issued by the Bank of Korea and the RAS techniques. And we analyzed the economic effects that can be drawn from the investment of the smart network industry. As a result, the gross production inductive effect which appears with the economic effect of the smart network establishment project from 2011 to 2015 came out to be about 72 trillion 808.2 billion KW, added value inductive effect of 44 trillion 192.9 billion KW and the employment inductive effect of the job creation of about 412 thousands people. Afterward, it is anticipated that the smart network build-up project to contribute to the improvement of Koreans' daily life. Moreover, this research will be used as a valued basic material in the pursuit of the future network projects.

• Korean journal of communication and information
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• v.35
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• pp.114-146
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• 2006

Now, Korea-U.S.A Free Trade Agreement talk is underway in Korea. In FTA talks, the issues on audio-visual sector including screen quota, opening of broadcasting and telecommunication to the U.S.A. are becoming a hot potato. Globalization has been speed up by mass media and telecommunications. Cultures are no longer bounded by specific place but, through the migration of persons and the electronic flows of information, ideas and images, transgress established boundaries. So issues and debates have to be focused on global culture and cultural imperialism. Some would argue global culture is the consequences of capitalist world-system, so dominance by the center should be criticized and vanished. Some would say that global culture would help recipient society's people with cultural diversify and improvement. The issues on culture and communication, particularly at international level call for our attention in light of cultural identity, homogenization and diversity. Although I criticize the cultural imperialism thesis, I suggest critical acceptance of cultural imperialism. That is the observation of complexity between internal and external dynamics. The process of cultural imperialism is not simple and unitary. It rather involves the various forces of internal dynamics along with external forces.

• Journal of KIISE:Information Networking
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• v.35 no.4
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• pp.251-267
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• 2008

In this paper, we present a distributed topology control algorithm for constructing an optimized topology having a minimal search-time in unstructured peer-to-peer network. According to the proposed algorithm, each node selects the best nodes having higher hit-ratio than other nodes as many as the number being exponentially proportional to the hit-ratio of the node itself, and then it connects to them. The ensemble behavior of the proposed algorithm is very similar to the recrystrallizing phenomenon that is observed in nature. There is a partial order relationship among the hit-ratios of most nodes of constructed topology. Therefore once query message visits a node, it has a higher hit-ratio than the node that was visited last by the message. The query message even sent from freeloader can escape to the node having high hit-ratio by one hop forwarding, and it never revisits any freeloader again. Thus the search can be completed within a limited search time. We also propose the Chain-reactive search scheme using the constructed topology. Such a controlled multicasting reduces the query messages by 43 percent compared to that of the naive Gnutella using broadcasting, while it saves the search time by 94 percent. The search success rate of the proposed scheme is 99 percent.