• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.53-56
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• 2002

본 논문은 2채널 스피커를 사용하여 청취자에게 보다 입체적인 음향 효과를 제시하기 위하여 크로스토크현상을 제거하고 청취자의 보다 자유로운 청취를 위해 최적 청취영역 확대를 위한 실험과 시스템 구현에 관한 것이다. 정면에 위치한 두 스피커로부터 교차경로인 크로스토크를 제거하기 위해 음질의 왜곡을 최소화하는 자유음장 모델을 이용하여 구현한 트랜스오럴 필터 사용하였고 최적 청취영역의 확대를 위해 스피커는 BPF(Band Pass Filter)를 이용하여 저주파와 고주파를 분리하여 각각 재생할 수 있는 스피커를 구성하였으며 저주파 영역은 제외하고 중고주파 영역을 이용하였으며 기존 크로스토크제거 시스템을 사용하여 고정된 한 점의 청취영역에서 좌${\cdot}$우로 5Cm씩 이동하au 100Cm까지 측정한 결과 30Cm, 55Cm, 75Cm, 90Cm, 100Cm에서 크로스토크제거됨을 알 수 있는 음의 분리도가 5dB이상 나타났다. 실험 결과 얻어진 각 지점들로부터 자유음장 모델을 이용하여 트랜스오럴 필터링 하였으며 각각의 간섭현상을 막기 위해 주파수 영역에서 심리음향에 기초한 1/3-Octave Band Pass Filter를 사용하여 음질 보상을 실시하였다. 음원을 제작하여 기존의 2채널 시스템에서 제시하는 음원을 각각의 위치의 음원과 비교하여 음질 평가를 실시하였으며 기존의 트랜스오럴 필터와 비교평가를 실시하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.11
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• pp.1078-1088
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• 2010

In order to analyze the quantitative characteristics of acoustic streaming, experimental setup of 3-D stereoscopic PIV(particle imaging velocimetry) was designed and quantitative ultrasonic flow fields in the gap between the ultrasonic vibrator and heat source were measured. Utilizing acoustic streaming induced by ultrasonic vibration, surface temperature drop of cooling object was also measured. The study on smart cooling method by acoustic streaming induced by ultrasonic vibration was performed due to the empirical relations of flow pattern, average flow velocity, different gaps, and enhancement on cooling rates in the gap. Average velocity fields and maximum acoustic streaming velocity in the open gap between the stationary cylindrical heat source and ultrasonic vibrator were experimentally measured at no vibration, resonance, and non-resonance. It was clearly observed that the enhancement of cooling rates existed owing to the acoustic air flow in the gap at resonance and non-resonance induced by ultrasonic vibration. The ultrasonic wave propagating into air in the gap creates steady-state secondary eddy called acoustic streaming which enhances heat transfer from the heat source to encompassing air. The intensity of the acoustic streaming induced by ultrasonic vibration experimentally depended upon the gap between the heat source and ultrasonic vibrator. The ultrasonic vibration at resonance caused the increase of the acoustic streaming velocity and convective heat transfer augmentation when the flow fields by 3D stereoscopic PIV and temperature drop of the heat source were measured experimentally. The acoustic streaming velocity of air enhancement on cooling rates in the gap is maximal when the gap agrees with the multiples of half wavelength of the ultrasonic wave, which is specifically 12 mm.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.572-574
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• 2014

Researches on three-dimensional multimedia has been performed actively in recent years. Virtual sound technology corresponding to virtual image should be provided to implement 3D multimedia with high quality. Head-related transfer function (HRTF) plays a key role in this research area. HRTFs measured in changing azimuth, elevation, and distance for each and every subject is necessary for ideal solution. However, it is practically impossible to measure all subjects' HRTFs, so various HRTF databases have been built by many researchers. Because HRTF displays quite different aspects from subject to subject, HRTF of dummy head has been used for generic usage. However, mannequin's HRTF showed much worse performance comparing with individual case so this solution should be improved. From previous work, standardization of HRTF based on tensor-singular value decomposition method has been proposed. For effective extraction of standard HRTF, three different decomposition methods are compared in this paper.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.1078-1080
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• 2013

본 논문에서는 5.1 채널 입체 음향 오디오 신호를 2채널의 헤드폰으로 재생하기 위해 사용하는 HRTF(Head-related transfer funcion) DB를 다룬다. 다양한 HRTF DB의 사례를 분석하고, 이를 통해서 더 나은 HRTF DB를 설계 한다. 기존의 HRTF DB에 Audio Meta data를 이용하여 파일의 정보를 저장하고, 이를 DB에 저장함으로써 Meta data를 비교 검색하고 저장함으로써 편의성을 높인다. 또한 기존의 HRTF DB들이 오래 되고 현재의 시스템에 맞지 않기 때문에 이를 현재의 시스템에 맞게 Converting하고 UI를 3D로 구현함으로써 UX를 높이고 직관성을 개선함으로써 사용자 접근성을 높인다. 이를 통해서 HRTF DB의 범용성을 개선하고 관련 연구에 효율적으로 사용할 수 있게 될 것이다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.4
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• pp.282-288
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• 2014

Three-dimensional multimedia industry such as 3D TV, movie and broadcast has been developed vividly. For generating 3D contents with high quality, virtual auditory display, so called VAD, is being researched to offer more realistic experience to listeners. When people render VAD using headphones or two speakers, head-related transfer function(HRTF) plays a key role. The best solution is measuring all individuals' HRTFs, but it is hard to measure all listeners' HRTFs. To overcome this difficulty, many research groups have tried to construct their own measurement system and to build HRTF databases. However, some of them have not enough subjects or spatial resolution and they are mainly focused on Caucasian. There exists difference between Korean and Caucasian in a view of physical features. In other words, if Koreans hear three-dimensional sound rendered by HRTF database based on Caucasian, performance might be hindered. To verify this possibility and remedy the drawbacks, construction of new HRTF database aimed at Korean is needed. Therefore, our laboratory built HRTF measurement system which can measure HRTF of three-dimensional space with dense spatial resolution. With this system, 55 Korean males and 45 females' HRTFs were measured and Korean HRTF database was built based on these data.

• The Transactions of the Korea Information Processing Society
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• v.3 no.1
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• pp.95-106
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• 1996

The most fundamental difference between general three dimensional computer graphics technology and virtual reality technology lies in the degree of realism as we feel, and thus the virtual reality method heavily relies on such tolls as data gloves, 3D auditory system to enhance human perception and recognition. Although these tolls are valid for such purpose, more essential ingredient. This paper provides further realism by modeling active interactions between the objects inside scenes. For this purpose, this paper proposes and implements a field model where the virtual reality space is treated as a physical field defined on the characteristic radius of stimulus and sense corresponding to the individual object. In the field model, the rule of cause and effect as an essential feature of the realism can be interpreted simply as an energy exchange between objects and consequently, variation on the radius information together with behavioral logic alone can build the virtual environment where each object can react to other objects actively and controllably.

• Journal of Broadcast Engineering
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• v.22 no.6
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• pp.829-849
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• 2017

Due to the large-scale TV display, the convergence of broadcasting and broadband, and the advancement of signal compression and transmission technology, terrestrial digital broadcasting has evolved into UHD broadcasting capable of providing simultaneous broadcasting of fixed UHD and mobile HD. The Korean standard for terrestrial UHDTV broadcasting is based on ATSC 3.0, the broadcasting standard of North America. The terrestrial UHDTV broadcasting standard chose that as a new AV codec standard, HEVC video codec which can compress with higher efficiency compared to AVC, and MPEG-H 3D audio codec for realistic audio. Also, DASH and MMT are adopted as transmission format instead of MPEG-2 TS to support broadband as well as broadcasting network, and in order to provide 4K UHD/mobile HD service simultaneously ROUTE multiplexing technology is applied. In this paper, we propose an audio/video encoder, which is required to provide HDR/WCG supported high quality video service, 10.2 channel/4 object supporting stereo sound service, fixed UHD and mobile HD simultaneous broadcasting service based on ATSC3.0, also we implemented the ATSC 3.0 LDM system for ROUTE/DASH packager, multiplexing system and physical layer transmission/reception, and verified the service ability by applying it to real time broadcast environment.

• 한국체육학회지인문사회과학편
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• v.54 no.4
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• pp.363-372
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• 2015

The purpose of this study was to suggest marketing plan to improve and promote screen baseball utilization, applying Importance-Performance Analysis (IPA) incorporating marketing mix 4Cs; Customer value, Convenience, Cost, and Communication. A convenience sample was made up of 267 users in screen baseball clubs located in metropolitan area. Evidence on validity and reliability of the data was obtained through exploratory factor analysis and internal consistency analysis. Frequency analysis and paired sample t-test for the difference verification of IPA were conducted also in SPSS version 21.0 with .05 of significance level. The main results of the study were as follows. First, there were partially significant differences between importance and satisfaction regarding the sub-categories of Customer value and Convenience. Second, there were all significant differences between importance and satisfaction regarding the sub-categories of Cost and Communication. Third, as the results regarding IPA, quadrant I indicating 'Keep up Good Work' included healthy use of leisure time, improvement of self-achievement, accessibility, communication between service user and provider, etc. Fourth, quadrant II indicating 'Concentrate Here' included diversification of screen baseball program, cost regarding facility use, etc. Fifth, quadrant III indicating 'Low Priority' included interpersonal relationship, subsidiary facilities, cost of food and beverage, etc. Lastly, quadrant IV indicating 'Possible Overkill' included improvement of physical health and life satisfaction and rules and procedures of screen baseball.