• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.684-691
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• 2001

In this paper, the BER performance of OFDM/M-ary PSK systems is analyzed with considering carrier-frequency offset and TCM technique, which encodes and modulations simultaneously, is adopted to OFDWM-ary PSK systems for compensation of performance degradation according to carrier-frequency offset. As a result of analysis, the error performance of OFDM/M-ary PSK systems is degraded as the frequency offset is increased. And the frequency offset should be below 0.025 in order to achieve $BER= 10^{-3}$ with $E_b/N_o$ of 10 dB. Especially, when the TCM technique is adopted to OFDM/M-ary PSK systems, the performance improvement of about 4 dB is obtained in terms of $E_b/N_o$.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.640-643
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• 2013

차량용 블랙박스는 영상, 음성 및 자동차의 주행정보를 저장하는 매체로서 저장되는 데이터를 통해 차량 접촉사고 시 운전자의 과실여부를 판단할 수 있는 중요한 장치로 최근 자동차 시장에서 많은 주목을 받고 있다. 그러나 현재 차량용 블랙박스는 단순히 주행 데이터를 저장만 하고 있어 법적인 근거 자료로 활용되기 위해서는 데이터에 대한 무결성 보장을 제공하는 기능이 없는 상황이다. 블랙박스에 저장된 데이터는 공격자에 의해 위, 변조될 위험이 존재함으로 본 논문에서는 보다 안전한 환경에서의 무결성 보장을 위해 클라우드 컴퓨팅 환경에서의 무결성을 제공하는 시스템을 설계 한다.

• Phonetics and Speech Sciences
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• v.15 no.3
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• pp.59-67
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• 2023

This study aimed to propose an appropriate evaluation method for the perceived level of speech disfluency based on sound prolongation (i.e., increased duration of segments). To this end, 34 Korean-speaking adults (9 males, 25 females, average age: 32.9 yrs.) participated as raters in this study. The participants listened to sentences containing a total of 25 stimuli with the Korean voiceless fricative /s/ extended by 80-ms increments up to 2,000 ms (i.e., 285 ms, 365 ms., ..., 2,125 ms, 2,205 ms), and evaluated them using an equal-appearing interval scale (EAI, 1-7 points, where 1 represents "normal" and 7 represents "severe"). Subsequently, based on the interval-scale results, the sentence stimuli with the prolonged voiceless fricative corresponding to the mild-to-moderate level (rated as 4 points) were selected as the reference modulus for direct magnitude estimation (DME). After scatter plots were created for the two evaluation results, the relationship between the two measured mean values was analyzed using a curve estimation method for the observed data with the highest R²-value to determine whether a linear or curvilinear approximation fit the data better. A curvilinear relationship between the two evaluation results was indicated, suggesting that DME is a more appropriate evaluation method than the EAI scale for assessing the perceived level of disfluency based on sound prolongation.

• Journal of Aerospace System Engineering
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• v.14 no.5
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• pp.122-129
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• 2020

Surion is required to install radios (U/VHF-AM, VHF-FM) capable of omni-directional communication. Therefore, this paper demonstrates the antenna performance test for the installation of the Surion communication antenna and the selection of optimal location. A simulation pattern analysis was performed employing the antenna, and a coupling test was performed by creating a new evaluation criterion. In addition, the results of the pattern flight test conducted at the previously suggested 1:20 turn and separation distance ratio were observed to be normal. However, the occurrence of voice cutoff was noted in the long-distance flight test. Therefore, in this paper, 1:300 (15 NM) is proposed as a new optimal ratio for predicting the long-distance flight test results in advance. Finally, the effectiveness of the proposed evaluation criteria was verified through long-distance flight tests. Consequently, it is expected to reduce the development schedule and cost by reducing the trial and error of the performance test for the Surion model. Also, the results of this study are expected to be used as standards for the installation of communication antenna and quality tests for other helicopters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.4
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• pp.545-551
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• 1998

The Radio communication by existing SSB, VHF, etc. in a coast station and a base station for military affairs is still used to a very important the device of information delivery or transmitting and receiving by the remote controller to using to the exclusive cable for a equipment established at a long distance. When a number of consumer to connected and operated by a number of transceiver is essential for a circuit controller of ICS, in KOREA, is devoted by import to considerable quantity because of to be delayed development of this field. This Paper has been realized to optimal algorithm and designing of a circuit connection controller by multi-processor to pre-stage for the development of ICS. The H/W is composed able to remote control to circuit connector with the several slave processor and a processor for master, and this has taken possible through without any obstacle to communication circuits of a control signal by FSK system. The S/W make possible monitoring for communication condition of other circuits by means of a serial communication system by the multi-processing. This paper has been studied for connecting to a circuits wished to rapidly and precisely by the full application to a interrupt technique. A technique to control by remote to a number of transceiver is a way increasing to application for a frequency resource of the limited MF/SF, VHF and the existing radio communication technique. According to, this paper will achieve to be the reduction of energy & equipment and multiplicity of information delivery in the general communication and disposal to rapid and exact for the important communication as distress, urgency and safety on the sea.

• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.343-349
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• 2004

Electroglottograph(EGG) is a signal recorded from the vocal cord vibration by measuring electrical impedance across the vocal folds through the neck skin. The purpose of this study was to develop EGG system and to evaluate possibility for the application on speech analysis and laryngeal disease diagnosis. EGG system was composed of two pairs of ring electrodes, tuned amplifier, phase sensitive detector, low pass filter, and auto-gain controller. It was designed to extract electric impedance after detecting by amplitude modulation method with 2.7MHz carrier signal. Extracted signals were transmitted through line-in of PC sound card, sampled and quantized. Closed Quotient(CQ), Speed Quotient(SQ), Speed Index(SI), fundamental frequency of vocal cord vibration(F0), pitch variability of vocal fold vibration (Jitter), and peak-to-peak amplitude variability of vocal fold vibration(Shimmer) were analyzed as EGG parameters. Experimental results were as follows: the faster vocal fold vibration, the higher values in CQ parameter and the lower values in SQ and SI parameters. EGG and speech signals had the same fundamental frequency. CQ, SQ, and SI were significantly different between normal subjects and patients with laryngeal cancer. These results suggest that it is possible to implement portable EGG system to monitor the function of vocal cord and to test functional changes of the glottis.

• Tuberculosis and Respiratory Diseases
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• v.43 no.3
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• pp.359-366
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• 1996

Background : Eosinophilic leukocytes are prominent cellular participants in the pathogenesis of allergic disease and asthma. Chemotaxis is still a very useful method in evaluating the response of human eosinophil to novel modulators. Degranulated mast cells and activated T lymphocytes are responsible for the pathophysiology of asthma and tryptase is one of most important proteases released after activation of mast cells. The purpose of this study was to investigate the actions of trypsin and chymotrypsin on eosinophils in terms of chemotaxis and activation. Method : Eosinophils were isolated by negative immunoselection from the peripheral blood of atopic donors. Chemotaxis was studied by using micro-Boyden chambers and ECP release was assayed by fluoroimmunoassay. Results : Eosinophil showed a chemotactic response to trypsin. Maximal chemotactic response was with $1000{\mu}g/ml$ trypsin ($56.52{\pm}14.50$/HPF) which was comparable to PAP. But chymotrypsin showed no significant chemotactic response to eosinophils. Trypsin at the concentration of 10, 100, $1000{\mu}g/ml$ induced secretion of ECP, which at the concentration of $10{\mu}g/ml$ represented about 2.7 times of the spontaneous rate of release. Soybean protease inhibitor reduced trypsin induced ECP release. Conclusion : Trypsin can induce chemotactic response to eosinophils and activation of eosinophils that can induce secretion of ECP. On the contrary, chymotrypsin showed no direct effect on eosinophils. We propose a role of trypsin on the chemotaxis and activation of eosinophils.

• Phonetics and Speech Sciences
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• v.14 no.2
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• pp.67-76
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• 2022

This study aimed to examine Korean listeners' mode of perceiving sound duration as prolongation, whether dichotomous or continuous. Thirty-five Korean participants (17 men and 18 women) listened to the Korean segment /s/, which was lengthened by 0-980ms in 20-ms increments. Then, the participants were asked to rate each version of the sound based on a rating of one to 100 (the closer to 100, the more disfluent). To examine whether listeners perceived durational variations for the fricative segment dichotomously or continuously, a curve was estimated using the best-fitting regression model for the observed data with the highest adjusted R-squared value. The mode of perceiving durational variations for the segment was continuous (or gradient) rather than discontinuous (or dichotomous). No gender difference was found in the mode of perceiving prolongation. However, there was a significant gender difference in that men rated the most disfluent sounds higher than women. The findings of this study were further discussed in relation to the existing literature, and clinical implications for the assessment of stuttering were presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1A
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• pp.19-27
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• 2011

WiBro is a wireless mobile communication system which supports a high data rate and high mobility in anywhere and anytime. Although WiBro system provides multimedia service including data, audio and video services, customers require better service quality in WiBro system. But, many researches have theoretically evaluated the performance of WiBro system without systematic studies by simulation. Therefore, in this paper, we evaluate a performance of WiBro system using OPNET simulator. We analyze system performance according to various modulation and coding schemes, and propose Adaptive Modulation and Coding (AMC) profile to support quality of services for user requirements. Also we evaluate the performance of WiBro system using AMC and Hybrid-Automatic Repeat Request (H-ARQ) technologies, and confirm that the proposed AMC profile can be applied to WiBro system with high performance.

• Journal of IKEEE
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• v.15 no.1
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• pp.15-22
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• 2011

In order to performing the joint operation of Korean army efficiently, informations about surveillance, reconnaissance, and situation awareness need to be possessed jointly. In the first development phase (basis type) of the Korean joint tactical data link system (JTDLS-K), essential tactical information and recognized situation are owned among platforms in common by using existing wireless terminals. In the second development phase (completion type) of the JTDLS-K, a JTDLS which can perform network centric warfare (NCW) will be developed in due consideration of technology development of the basis type and common technology maturity degree. This is a joint battlefield system that can show fighting power simultaneous and polysynthetically through providing command and control messages effectively to each platform, which is participating in the joint and combined operations. In this paper, the development of JTDLS-K with a common data processor based on common link integration processing (CLIP) is described. From the test results of the system presented in this paper, it is demonstrated that quadrature phase shift keying (QPSK) signals can be applied to the system.