• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권4호
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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.

• 한국통신학회논문지
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• 제16권6호
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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.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.750-752
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• 2010

MANET은 노드간의 이동성을 지원하고 추가의 인프라가 필요 없는 무선 이동 네트워크로 관심을 받고 있다. MANET의 노드 이동속도는 보행속도에서 차량이동속도에 이르기까지 다양하다. 본 연구에서는 MANET에서 VoIP 성능을 노드 이동속도 측면에서 분석해본다. 노드의 이동속도를 보행속도, 차량속도 및 고속이동으로 분류하여 VoIP 성능을 분석한다. 성능 파라메타로는 PDR(Packet Delivery Ratio), MOS(Mean Opinion Score)를 사용했다.

• 방송공학회논문지
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• 제12권2호
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• pp.177-184
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• 2007

본 논문에서는 멀티미디어 응용을 위한 동영상의 주관적 품질평가방법으로 널리 사용되는 DSCQS(Double Stimulus Continuous Quality Scale method) 및 ACR(Absolute Category Rating)방법을 비교분석하였다. 두 가지 방법을 비교 실험한 결과 MOS (Mean Opinion Score) 값의 경우 DSCQS와 ACR의 평가치가 매우 높은 상관도를 보이는 것을 확인할 수 있었다. 또한 DMOS (Difference Mean Opinion Score)값의 경우에는 DSCQS와 ACR 방법이 MOS 값의 경우보다 약간 낮은 정도의 상관도를 보였다. 이 같은 결과는 ACR 방식이 DSCQS에 필적하는 성능을 제공하며 많은 수의 영상을 평가 할 수 있는 효율적인 주관적 품질평가 방법임을 보여주고 있다.

• 대한전자공학회논문지SP
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• 제44권5호
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• pp.11-19
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• 2007

본 논문은 디지털 모바일 비디오에 대한 객관적 화질 평가 방법을 제안한다. 본 논문에서 제시한 방법은 경계 영역 특징과 블로킹 효과를 측정하는 주요 인자를 제안하고, 영상 전체의 열화 정도를 반영하여 주관적 화질을 객관화 하였다. 제안한 알고리듬의 성능 평가를 위해서 CIF/QCIF 140개 비디오에 대하여 Double-Stimulus Continuous Quality Scale(DSCQS) 방법의 주관적 화질 평가를 실시하여, Mean Opinion Score(MOS) 값을 얻었다. MOS 결과를 기존 방법의 결과와 제안한 방법의 결과와 비교하여 에러를 분석한 결과, 기존의 방법에 비해 제안한 알고리듬의 성능이 약 25%이상 향상되었음을 보였다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.795-797
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• 2009

Voice over IP(VoIP) 서비스가 많이 사용함에 따라 각종 Network Model 기반의 VoIP 서비스 기술이 제시 되어 있다. VoIP 서비스에 대한 품질 평가 척도인 Mean Opinion Score(MOS)[1]가 보장하려면 안정된 Network 환경을 지원해야 한다. 하지만 Mobile Ad-Hoc Network(MANET) 기반의 VoIP 서비스인 VoMANET은 MANET의 불안정성이 가져온 Packet Loss와 Delay 때문에 좋은 MOS를 얻을 수가 없다. 본 논문에서는 NS-2(Network Simulation-2)[2]를 이용하여 VoMANET을 분석하였다. 그리고 Network Topology 크기와 노드의 밀도를 조절하여 받은 다른 결과를 참조하고 VoMANET 성능의 개선 방안을 제시한다.

• Asian-Australasian Journal of Animal Sciences
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• 제28권11호
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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.

• 전기학회논문지
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• 제58권4호
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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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• 제2권2호
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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.

• 한국정보통신학회논문지
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• 제14권5호
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• pp.1109-1116
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• 2010

본 논문에서는 시뮬레이션을 사용하여 MANET(Mobile Ad-hoc Network)에서 VoIP(Voice over Internet Protocol) 트래픽의 전송성능을 측정 분석하였으며, 이를 토대로 VoIP 구현 조건을 제시하였다. 시뮬레이션에는 NS(Network Simulator)-2를 기반으로 한 VoIP 시뮬레이터를 구현하여 사용하였으며, 시뮬레이션에 사용한 VoIP 트래픽은 G.711, G.723.1 G.726-32, G.729A, GSM.AMR, iLBC 규격을 기준으로 생성하였다. 이 트래픽을 $670{\times}670m$ 50노드 규모의 MANET 환경에서 전송하고, VoIP 전송 성능으로 MOS(Mean Opinion Score), 네트워크 지연, 패킷손실율, 전송대역을 측정하였다. 측정결과에 대한 정규화분석을 통하여 VoIP 서비스 품질 조건을 충족하는 VoIP 연결수가 15이하임을 확인하였다.