• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.4
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• pp.1351-1372
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• 2022

A self-organizing multiple unmanned aerial vehicles (multi-UAVs) deployment based on virtual forces has a difficulty in ensuring the quality-of-experience (QoE) of users because of the difference between the assumed center for users in a hotspot and an actual center for users in the hotspot. This discrepancy is aggravated in a non-uniform and mobile user distribution. To address this problem, we propose a new density based virtual force (D-VF) multi-UAVs deployment algorithm which employs a mean opinion score (MOS) as a metric of QoE. Because MOS is based on signal-to-noise ratio (SNR), a sum of users' MOS is a good metric not only to secure a wide service area but to enhance the link quality between multi-UAVs and users. The proposed algorithm improves users' QoE by combining virtual forces with a random search force for the exploration of finding multi-UAVs' positions which maximize the sum of users' MOS. In simulation results, the proposed deployment algorithm shows the convergence of the multi-UAVs into the position of maximizing MOS. Therefore, the proposed algorithm outperforms the conventional virtual force-based deployment scheme in terms of QoE for non-uniform user distribution scenarios.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.6
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• pp.509-516
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• 1991

In this paper, we propose on objective evaluation model of telephone transmission qulity in order to estimate a satisfaction score regarding speech quality in a relephone network. As the degradantion factors of telephone transmission quality, this model takes into account transmission loss, noise, distortion, talker echo and sidetone. A performance index[PI] is introduced for five psychological factors affecting telephone speech qualty, and a Mean Opinion Score(MOS) is estimated from the sum of all Pis. The simulation results indicate theat the MOS obtained from the objective evaluation model is in good agreement with that of subjective evaluation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.750-752
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• 2010

MANET has some interest as a wireless mobile network supporting node mobility and having no additional infrastructure. Speed of mobile node on MANET is various from just slow speed of human's walk to vehicle's moving speed. In this study, VoIP performance of MANET is evaluated in the view of speed of mobile node. VoIP performance is studied on walking speed, vehicle speed and higher speed on MANET. PDR(Packet Delivery Ratio), MOS(Mean Opinion Score) are used as performance parameters.

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.177-184
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• 2007

In this paper, we compared two subjective assessment methods DSCQS(Double Stimulus Continuous Quality Scale method) and ACR(Absolute Category Rating). These methods are widely used in order to evaluate video quality for multimedia application. We performed subjective quality tests using DSCQS and ACR methods. The subjective scores obtained by the DSCQS and ACR methods show that these methods are highly correlated in terms of MOS(Mean Opinion Score) and have slightly lower correlation in terms of DMOS(Difference Mean Opinion Score). The results indicate that ACR method is an effective subjective quality assessment method, which shows compatible performance with DSCQS method and can evaluate a larger number of video sequences.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.5
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• pp.11-19
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• 2007

This paper presents an objective video quality evaluation method for digital mobile video. The proposed method is to objectify subjective quality by extracting edge region feature metric and blockiness effect. To evaluate performance of proposed algorithm, we carried out subjective video qualify test with the DSCQS method and obtained mean opinion score(MOS) values for CIF/QCIF 140 video clips. We compared error of proposed method with that of existing. The experiment results show that the proposed method has 25% higher performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.795-797
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• 2009

Voice over Internet Protocol(VoIP) service becomes more and more popular nowadays. As such, it is developed over many kinds of network models, especially wireless networks. Mean Opinion Score(MOS) computes the QoS of VoIP service which should be supported by robust network environment. However, MANET is not stable enough to supply high MOS values for VoIP service. In this paper, VoIP service over MANET is simulated using ns-2(Network Simulation 2). In oder to get different MOS values in the results, we differentiate between network environments by adjusting the parameters of MANET.Through comparing the results we can know how to improve the QoS.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.11
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• pp.1599-1605
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• 2015

Twenty Holstein calves were used to investigate the effects of mannanoligosaccharides (MOS) supplementation in the whole milk on growth performance, faecal score, faecal pH, selected faecal bacterial populations and health during the preweaning period. Healthy calves selected by clinical examination were allocated to one of the two groups (control [CG] and experimental [EG]) at 5 days old. Each group consisted of 5 male and 5 female calves. Each calf in EG was supplemented with 7 g/d of a MOS product (Celmanax) from 5 days to 56 days of age. MOS supplement was mixed with the whole milk once in the morning and administered to the calves in EG via nipple bottle, whereas the calves in CG were fed the whole milk without MOS. Calves were weaned at 56 days of age. The final body weight, average daily weight gain (ADG) and average daily feed intake (ADFI) were statistically similar (p>0.05) but were higher by 3.70%, 6.66%, and 10.97%, respectively, in MOS than in control calves. Feed efficiency (ADG/ADFI) was also similar in two calves group. While faecal scores did not differ on day 5, 7, 14, 21, 28, 42, 49, and 56 between groups, EG had a higher faecal score (p = 0.05) than CG on day 35. Faecal concentration of Lactobacillus was lower (p<0.05) in EG compared with CG. No differences (p>0.05) in faecal concentrations of Bifidobacterium, Clostridium perfringens, and Escherichia coli were found between groups. Although there were no significant differences (p>0.05) in the incidence of diarrhoea, treatment days for diarrhoea and the costs associated with diarrhoea treatments between groups, collectively, the observed reductions in treatment days and the cost of diarrhoea treatments accompanying increases in final body weight, ADG and ADFI for EG may indicate potential benefit of MOS in treatment of diarrhoea.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.4
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• pp.857-866
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• 2009

In this paper, a noise cancellation-method using microphone array for digital hearing aids is proposed. The microphone array is located around the ear of a dummy. Speech sound is generated from the forward speaker positioned in the front of the dummy and noise sound is generated from the backward speaker. The speech and noise are mixed in the air space and entered into the microphones. VAD(voice activity detector) and ANC(adaptive noise cancellation) methods were used to eliminate noise in the sound of the microphones. 10 two-syllable words and 4 sentences were used for speech signals. Babble and car interior noise were used for noise signals. The performance of the proposed algorithm was evaluated by SNR(signal-to-noise ratio) and PESQ-MOS(perceptual evaluation of speech quality-mean opinion score). In babble noise condition, SNR was improved as much as $7.963{\pm}1.3620dB\;and\;3.968{\pm}0.6659dB$ for words and sentences respectively. In the case of car interior noise, SNR was improved as $10.512{\pm}2.0665dB\;and\;6.000{\pm}1.7642dB$ for words and sentences respectively. PESQ-MOS of the babble noise was improved as much as $0.1722{\pm}0.0861$ score for words and $0.083{\pm}0.0417$ score for sentences. And PESQ-MOS of the car interior noise was improved as $0.2661{\pm}0.0335$ score and $0.040{\pm}0.0201$ score for words and sentences respectively. It is verified that the proposed algorithm has a good performance in noise cancellation of microphone array for digital hearing aids.

• Communications for Statistical Applications and Methods
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• v.2 no.2
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• pp.176-183
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• 1995

Mean opinion score (MOS) method has been used in many areas to quantify opinions of respondents not only in survey research but in evaluating the parameters of population that are not measurable of are technically hard to be measured. Histogram is an important graphical technique because of the role it plays in describing categorical data as well as quantitative. In MOS method, subjective opinions of respondents are quantified by opinion scores and the arithmetic means of opinion scores have been used to describe the interesting population. Since opinion scores are polytomous, the values of arithmetic means have little meanings. In this paper, cumulative percentage curves as a function of the means of opinion scores are derived by combining means of opinion scores and histograms. It is proposed for better interpretation to opinion scores in MOS method, one of subjective evaluation methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1109-1116
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• 2010

In this paper, some performance characteristics of VoIP(Voice over Internet Protocol) for MANET(Mobile Ad-hoc Networks) with simulation is studied and appropriate condition for implementation of VoIP service is suggested. VoIP simulator is implemented with NS(Network Simulator)-2. VoIP traffic for simulation is generated with some codecs of G.711, G.723.1, G.726-32, G.729A, GSM.AMR and iLBC. As simulation results for traffic transmission under $670{\times}670m$ 50node MANET environment, performance data for MOS(Mean Opinion Score), network delay, packet loss rate and transmission bandwidth are measured. Normalized analysis about measured results shows that maximum VoIP connection satisfying VoIP service quality condition is 15.