• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.975-984
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• 2022

Since a linear transducer has an area of interest equal to the length of the transducer, the area of interest can be expanded using the virtual convex function installed in the device.However, it was thought that the change in the direction of the ultrasonic sound velocity according to the change in the visual area of interest would affect the image quality, so this was objectively confirmed. For this study, image evaluation and SNR·CNR of the phantom for ultrasound quality control were measured. As a result, in the phantom image evaluation, both images were able to identify structures in functional resolution, grayscale, and dynamic range. However, it was confirmed that the standard image was excellent in the reproducibility of the size and shape of the structure. As a result of SNR·CNR evaluation, SNR·CNR of most trapezoidal images was low, except for structures at specific locations. In addition, through the statistical analysis graph, it was further confirmed that the SNR and CNR for each depth decreased as the size of the cystic structure decreased. Through this study, it was confirmed that the use of the function has the advantage of providing a wide visual area of interest, but it has an effect on the image quality. Therefore, when using the virtual convex function, it is judged that the examiner should use it in an appropriate situation and conduct various studies to acquire high-quality images and to improve the understanding and proficiency of the equipment.

• Archives of design research
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• v.16 no.4
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• pp.121-128
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• 2003

This is the research to find out which one is the best for using manual among the 3 kinds of methods such as 'Text manual' and 'Animation I' and 'Animation II' which is made by Virtual Realities. Three kinds of methods have been experimented respectively. The manual for 'Animation I' adopt the motion video with basis sound and the additional comment and sound is added on the 'Animation II'. Every 3 manual has been studied and estimated by T-test and additional subjective estimation respectively, and the conclusions are as follows. The 1st answer is that 'Animation manual' is more easier than 'text manual', and the 2nd answer is that 'Animation II' is easier than 'Animation I'. Through post-interview and test, It is known that the animation manuals, which has been showing the multimedia, is more attractive than text manual.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.4
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• pp.201-207
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• 2013

Voice Recognition technique has been developed and it has been actively applied to various information devices such as smart phones and car navigation system. But the basic research technique related the speech recognition is based on research results in English. Since the lip sync producing generally requires tedious hand work of animators and it serious affects the animation producing cost and development period to get a high quality lip animation. In this research, a real time processed automatic lip sync algorithm for virtual characters in digital contents is studied by considering Korean vocal sound system. This suggested algorithm contributes to produce a natural lip animation with the lower producing cost and the shorter development period.

• Journal of Broadcast Engineering
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• v.10 no.1 s.26
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• pp.22-30
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• 2005

We implement an interactive 3D audio broadcasting terminal which synthesizes an audio scene according to the request of a user. Audio scene structure is described by the MPEG-4 AudioBIFS specifications. The user updates scene attributes and the terminal synthesizes the corresponding sound images in the 3D space. The terminal supports the MPEG-4 Audio top nodes and some visual nodes. Instead of using sensor nodes and route elements, we predefine node type-specific user interfaces to support BIFS commands for field replacement. We employ sound spatialization, directivity/shape modeling, and reverberation effects for 3D audio rendering and realistic feedback to user inputs. We also introduce a virtual concert program as an application scenario of the interactive broadcasting terminal.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.8
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• pp.1035-1044
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• 2010

Head-related transfer function (HRTF) is an acoustic transfer function from a sound source to the ear canal entrance position. HRTFs are very important information in the construction of virtual sound fields. HRTFs also vary for different individuals. In this study, characteristics of HRTF for an average Korean are investigated numerically by comparing with the HRTF for a standard Knowles Electronics Manikin for Acoustic Research (KEMAR). A boundary element (BE) model for an adult Korean is developed using the computerized tomography (CT) data in order to investigate the variation in HRTFs for different individuals. The boundary conditions of the BE model are identified by comparing the numerical results with the experimental results. The numerical model shows that accurate HRTFs can be calculated efficiently over full audible frequency range for individuals.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.1
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• pp.28-36
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• 2018

The experimental results of the model tests for the twin propeller cavitation noise are presented. The model test was carried out by means of procedure of noise measurement followed by the signal processing and full-scale extrapolation. In order to convert the measured sound pressure level into the sound source level, transfer function measurements for three conditions were performed according to the combination of locations and number of virtual sources. White noise and LFM signal were used as a source signals to examine the influence of the input signal. For the twin propellers, 5 transfer functions were defined and the results were discussed. Cavitation noise measurement tests were performed similarly to the transfer function measurement test. Noise source localization analysis was performed to confirm the test effectiveness. It was confirmed that the source level of the twin propeller can be estimated reliably by using transfer function corrections. Finally, the model test results were converted into full-scale by applying the ITTC '87 model-ship scaling raw, and the validity of the model test was confirmed by comparison with the full-scale measurement result.

• Journal of Broadcast Engineering
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• v.24 no.6
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• pp.1002-1012
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• 2019

360VR content requires short latency, such as immediate response to viewers' viewport changes and high quality video delivery. It is necessary to consider efficient transmission that guarantees the QoE(Quality of Experience) of the 360VR contents with limited bandwidth. Several research has been introduced to reduce overall bandwidth consumption by predicting a user's viewport and allocating different bit rates to the area corresponding to the viewport. In this paper, we propose novel viewport prediction scheme that uses sound source location information of 360VR contents as auditory recognition information along with visual recognition information. Also, we propose efficient transmission algorithm by allocating a bit rate properly based on improved viewport prediction. The proposed scheme improves the accuracy of the viewport prediction and provides high quality videos to tiles corresponding to the user's viewpoint within the limited bandwidth.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2125-2130
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• 2016

In this paper, we researched the excellency of 3D graphic nursery contents which is developed by mobile AR technology. AR technology has currently people's attention because of the potential to be core contents of future ICT industry. We applied AR nursery contents for kid's subtitle language selection in Korean, Chinese and English education. The original fairy tale consisted of 6~8 scenes for the 3D contents production, and was adapted and translated. Dubbing was dubbed by the native speaker using the standard pronunciation, and the effect sound was edited separately to fit the scene. After composing a scenario, constructing a 3D model, constructing a interaction, constructing a sound effect, and creating content metadata, the Unity 3D game engine is executed to create a project and describe it as a script. It provides a fun and informative tradition of fairy tales with abundant content that incorporates ICT technology, accepting advanced technology-based education, and having opportunities to perceive software in daily life.

• The Journal of the Acoustical Society of Korea
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• v.41 no.6
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• pp.713-722
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• 2022

In this paper, the flow performance and aero-acoustic noise generated by the target centrifugal fan system were investigated numerically and experimentally. Also, the numerical method for Computational Aero-Acoustics were evaluated by comparing each method. To analyze the performance of the centrifugal fan experimentally, the acoustic power level was measured in the semi-anechoic chamber using microphones, and the active frequency range for the noise performance was identified and that frequency range was applied for Computational Aero-Acoustics (CAA) techniques as sampling frequency. Then, Navier-Stokes equation and the Ffowcs Williams&Hawking equations were used to analyze the flow and sound power numerically, respectively, and a virtual acoustic radiation plane was designed and used for the implementation of the sound field. The accuracy and numerical characteristics of the numerical methods were validated by comparing simulated acoustic power levels with acoustic power levels measured.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.90-99
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• 2003

Java applets are downloaded from web server through internet and executed in Java Virtual Machine of clients' browser. Before execution of java applets, JVM checks bytecode program with bytecode verifier and performs runtime tests with interpreter. However, these tests will not protect against undesirable runtime behavior of java applets, such as denial of service attack, email forging attack, URL spoofing attack, and annoying sound attack. In order to protect malicious applets, a technique used in this paper is java bytecode modification. This technique is used to restrict applet behavior or insert code appropriate to profiling or other monitoring efforts. Java byte modification is divided into two general forms, class-level modification involving subclassing non-final classes and method-level modification used when control over objects from final classes or interface. This paper showed that malicious applets are controlled by java bytecode modification using proxy server. This implementation does not require any changes in the web sever, JVM or web browser.