• The Journal of the Acoustical Society of Korea
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• v.31 no.2
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• pp.93-99
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• 2012

For speech coding, a vocal tract is modeled using Linear Predictive Coding (LPC) coefficients. The LPC coefficients are typically transformed to Line Spectral Frequency (LSF) parameters which are advantageous for linear interpolation and quantization. If multidimensional LSF data are quantized directly using Vector-Quantization (VQ), high rate-distortion performance can be obtained by fully utilizing intra-frame correlation. In practice, since this direct VQ system cannot be used due to high computational complexity and memory requirement, Split VQ (SVQ) is used where a multidimensional vector is split into multilple sub-vectors for quantization. The LSF parameters also have high inter-frame correlation, and thus Predictive SVQ (PSVQ) is utilized. PSVQ provides better rate-distortion performance than SVQ. In this paper, to implement the optimal predictors in PSVQ for voice storage devices, we propose Multi-Frame AR-model based SVQ (MF-AR-SVQ) that considers the inter-frame correlations with multiple previous frames. Compared with conventional PSVQ, the proposed MF-AR-SVQ provides 1 bit gain in terms of spectral distortion without significant increase in complexity and memory requirement.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.1-8
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• 2011

Power Line Communication (PLC: Power Line Communication) to propagate the current power lines are in every household of the existing infrastructure is the most extensive network configuration. In addition, the cost required for network configuration, the advantage of almost zero for the investors and is sufficient to attract the attention of operators. The PLC is supply power to power lines used the voice and data communication technologies put it on KHz ~ tens of hundreds of high-frequency signal MHz. But because uses power lines as existing wireless communications systems will occurs interference. The notch filters of a common way to eliminate the interference are used. In this paper, a dynamic high-performance notch filter applying CIC filter performance was verified through MATLAB and was implemented using a TI's TMS320C6416T DSP board.

• Korean Journal of Optics and Photonics
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• v.23 no.5
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• pp.217-221
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• 2012

In this paper, we have fabricated by means of the "Micro-Block Stacking (MBS)" method the 8 pin mini DIL integrated Triplexer, which can transmit CATV and voice/data at the same time in a single fiber. Our MBS technique is a novel scheme of compact optical module packaging which secures precision positioning of the components on the optical beam path by prefixed stacks of ceramic blocks. The subassembly in which a laser diode, two receiver photodiodes, two WDM filters, and four micro lenses are integrated is only $5.40mm{\times}2.15mm{\times}1.05mm$ in size. As the Triplexer is aligned to the single mode fiber, the transmitter power of -14.5 dBm and the receiver sensitivities of 0.83 A/W, 0.73 A/W for 1550 nm, 1490 nm, respectively are obtained.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.16 no.1
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• pp.10-14
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• 2005

Background and Objectives : Vowels are characterized on the basis of formant patterns. The first formant(F1) is determined by high-low placement of the tongue, and the second formant (F2) by front-back placement of the tongue. The fundamental frequency(F0) of a soprano often exceed the normal frequency of the first formant. And the vocal intensity is boosted when F0 is high and a harmonic coincides with a formant. This is called a formant tuning. Experienced singers thus learned how to tune their formants over a resonable range by lowering the tongue to maximize their vocal intensity. So, the current study aimed to identify the formant tuning in one experienced soprano by comparing the first formants of vowel [i] in three different voice production : speech, ascending scale, and vocalize. Materials and Method : All voices recordings of vowel [i] in speech, ascending scale (from F4 note to A4 note), and vocalize(:Ridente la calam") were made with digital audio tape-corder in a sound treated room. And the captured data were analyzed by the long term average(LTA) power spectrum using the FFT algorithm of the Computerized Speech Lab(CSL, Kay elementrics, Model, 4300B). Results : Although the first formant of vowel [i] in speech was 238Hz, those of ascending scale [i] were 377Hz, 405Hz, 453Hz respectively in F4(349z), G4(392Hz), A4(440Hz) note, and 722Hz, 820Hz, 918Hz respectively in F5 (698Hz), G5(784Hz), A5(880Hz) note. In vocalize, first formants of [i] were 380Hz, 398Hz, 453Hz respectively in F4, G4, A4 note, and 720Hz, 821Hz, 890Hz respectively in F5, G5, A5 note. Conclusion : These results showed that the first formant of ascending scale and vocalize sustained higher frequency than fundamental frequency in high pitch. This finding implicates that the formant tuning of vowel [i] in ascending scale was also noted in vocalize.

• Phonetics and Speech Sciences
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• v.6 no.4
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• pp.195-203
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• 2014

The aim of this study was to investigate the effects of phonation types ([+/- aspirated], [+/- fortis]) on aerodynamic measures with Korean bilabial stops. Sixty-three healthy young adults (30 males, 33 females) participated to evaluate the VOEF (Voicing Efficiency) tasks with bilabial stop consonants /$p^h$/, /p/, /p'/ using Phonatory Aerodynamic System (PAS) Model 6600 (Kay PENTAX Corp, Lincoln Park, NJ). All VOEF measures were significantly influenced by phonation types except RANP(pitch range)(p <.01). For sound pressure, maximum SPL, mean SPL, and Mean SPL during Voicing have been shown to be significantly greatest in fortis stop /p'/ than aspirated /$p^h$/ and lenis stop /p/ (p<.001). On the other hand, mean pitch after lenis stop was significantly lower than after aspirated and fortis stops (p<.001). Peak expiratory airflow, Target airflow, and FVC (Expiratory volume) were significantly lowest in fortis stop /p'/ which might be associated with higher aerodynamic resistance while peak air pressure and mean peak air pressure during closure were significantly lower in lenis stop /p/. Additionally, AEFF (Aerodynamic efficiency) was significantly higher in fortis stop /p'/ than lenis stop /p/ as well as aspirated stop /$p^h$/ (p<.001). Thus, sound pressure, airflow parameters, and aerodynamic resistance made crucial roles in distinguishing fortis /p'/ from lenis stop /p/ and aspirated. Additionally, pitch and subglottal air pressure parameters were important aerodynamic characteristics in distinguishing lenis /p/ from fortis /p'/ and aspirated /$p^h$/. Therefore, accurate aspirated /p/ stop consonant should be elicited when collecting the airflow, intraoral pressure related data with patients with voice disorders in order to enhance the reliability and relevance or validity of aerodynamic measures using PAS.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.1
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• pp.70-80
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• 2006

The large portion of communication service areas move from a legacy wire-line voice service to mobile data service. For the purpose of satisfaction on market need, many communication systems should be installed and upgraded based on a mobile wide-band transmission facility. Recently, large part of communication service is based on internet protocol by packet switch techniques and required new technologies such as multimedia processing, QoS achievement, and mobility managememobile communication network such as IS-95A/B and CDMA2000-1X. In this paper, I analyzed the network architecture and service provision methods. in CDMA2000-1X nt. In korea, a CDMA communication technique is standardized for digital mobile communication systems. By using the analysed results, I will extract an efficient method for network evolution and a core technique for next generation mobile communication network.

• Journal of Korea Multimedia Society
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• v.11 no.1
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• pp.117-128
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• 2008

Recently, as the increase in interaction between the person and the person, the people plentifully use the business card to exchange personal information. So, the people have many business cards. Thus, the people are liable to lose the business cards and finding a wanted business card is very difficult in the huge business cards in offline. And, the people think the business card is a way, which can express individuality. So, the people want to have the business card, which has individuality. Thus, this paper proposes the card system, which is satisfied to solve many problems of the card system in offline and express individuality. The proposed business card system can produce various business cards and puts contents such as video, photo, voice into business cards via mobile devices in anywhere, anytime. Also, this business card system follows the vCard format, which is a file format standard for personal data interchange. Finally, we provide with content-based business card retrieval using video and photo inserted into business cards. Thus, this paper proposes the hybrid business card system, which is satisfied to produce business cards expressed individuality and follows the vCard format.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.6
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• pp.1065-1071
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• 2009

Satellite application services can be divided into realtime services like voice communications and non-real time services like traditional data communications. To support both types of services on the same On-Board Switching(OBS), a scheduler which depends on their service classes is required. A fixed priority scheduling policy has a starvation problem. In this paper we propose a scheduling scheme based on premium and age. Premium is a fixed value which is given to a certain class of services. Age is another parameter of the scheduling policy and it will be increased by one for every scheduling cycle. The scheme we propose chooses a packet which has the largest sum of its age and premium. Simulation results indicate that the proposed approach shows better performance in both average cell delay and std-dev of cell delay for the lower class of service. There is no staying in infinite starvation state.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.6
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• pp.903-909
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• 2018

In December 2017, the world's first LTE-R for 250km/h high-speed railway was commercialized with the opening of Wonju-Gangneung high-speed railway. LTE-R has many advantages such as voice and video call, high-speed data transmission, coverage redundancy and DU redundancy. But it requires efficient use of radio resources because of a limited bandwidth of 10MHz for UL and DL, respectively. The existing unicast scheme has limited high frequency efficiency so when the number of users increases, service is limited due to the network load, which could be a problem for LTE-R in terms of stability and reliability. On the other hand, the multicast scheme via eMBMS can provide stable service even if the number of video users is high. This paper derives the number of unicast scheme users considering the LTE-R network with LAB test and calculation result, and proposes implementation plans and considerations for eMBMS commercialization on LTE-R.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.12
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• pp.1148-1159
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• 2012

It is of great significance in the NGN - which supports a ubiquitous network environment in which users can use multiple devices and all the devices are connected to networks - to support the terminal mobility as well as service continuity. The IMS architecture, which is considered as session control layer in the NGN, exists to support a wide range of advanced new services in addition to the traditional voice and data connectivity offerings of "old" telecommunications. The recent IMS specification also defines IUT (Inter UE Session Transfer) functionality in order to support service continuity in the NGN. However, service continuity in IMS has a limitation that two terminals involved in session transfer should belong to the same user. In this paper, we proposed a new device discovery mechanism for IMS and extended UEs with a few capabilities to overcome some of IMS's limitations. We also analysed how much overhead of the proposed method in terms of signaling cost will be.