• 제목/요약/키워드: Multimedia Broadcasting

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4K-UHD 비디오 시청환경 특성분석을 위한 주관적 화질평가 분석 (Analysis on Subjective Image Quality Assessments for 4K-UHD Video Viewing Environments)

  • 박인경;하광성;김문철;조숙희;최진수
    • 방송공학회논문지
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    • 제15권4호
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    • pp.563-581
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    • 2010
  • 본 논문에서는 초고해상도(UHD: Ultra High Definition) 영상의 방송 서비스를 위한 UHD 영상의 주관적 화질 평가를 수행하고 이에 따른 화질평가 결과를 분석하였다. TV, 인터넷, 개인 미디어 기기들의 보급으로 인해 영상 콘텐츠의 소비가 늘어나고 있으며 이와 더불어 고화질 영상에 대한 수요 또한 증가하고 있다. 현재 HD급($1920{\times}1080$) 영상이 DTV, DVD, 디지털 캠코더, 감시 비디오 및 기타 멀티미디어 기기 등을 통하여 다양한 형태로 소비되고 있으며, 최근에는 이러한 HD 해상도를 넘어 4K-UHD($3840{\times}2160$) 해상도의 디지털 시네마 콘텐츠가 활발히 제작되고 있고, 멀티미디어 시장에서도 이를 지원하는 카메라, 빔 프로젝터, 디스플레이 등의 기기가 출시되기 시작하였으며, 곧 방송${\times}$통신 환경에서도 4K-UHD 비디오 서비스가 출현할 것으로 예상된다. 이에 본 논문에서는 UHD TV 서비스 도입 시에 UHD 비디오의 시청환경 및 신호규격을 결정하는데 도움을 주기 위해 4K-UHD 영상에 대해 공간 해상도, 컬러포맷, 프레임률, 압축률을 포함한 4 가지 항목에 대한 주관적 화질 평가 실험을 수행하였다. 평가 결과, HD 해상도 대비 UHD 해상도의 영상에 대해 더 높은 주관적 화질 평가 결과를 보였으며, 컬러포맷이 YUV444인 4K-UHD 영상이 YUV422, YUV420인 4K-UHD 영상들 보다 화질이 더 높은 주관적 평가를 받았고, YUV422와 YUV420 4K-UHD 영상 간의 화질 비교에서는 주관적 평가 차이는 미미한 것으로 나타났다. 프레임률에 있어서는 60fps의 4K-UHD 영상이 30fps의 4K-UHD 영상보다 움직임이 많은 영상일수록 더 높은 주관적 화질 평가 결과를 보였으며, HD 영상에 대한 비트심도 비교에서는 10bit인 영상과 8bit인 영상 간의 주관적 화질 평가차이는 매우 작은 것으로 나타났다. 마지막으로 복${\times}$부호화된 4K-UHD 영상의 PSNR이 높을수록 높은 주관적 화질평가를 받았으며 시청거리가 멀어질수록 부호화에 의한 화질 열화를 인지하는 능력이 떨어지면서 PSNR이 낮은 영상도 화질이 양호한 것으로 평가되는 경향이 있었다.

Perceptional Change of a New Product, DMB Phone

  • Kim, Ju-Young;Ko, Deok-Im
    • 마케팅과학연구
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    • 제18권3호
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    • pp.59-88
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    • 2008
  • Digital Convergence means integration between industry, technology, and contents, and in marketing, it usually comes with creation of new types of product and service under the base of digital technology as digitalization progress in electro-communication industries including telecommunication, home appliance, and computer industries. One can see digital convergence not only in instruments such as PC, AV appliances, cellular phone, but also in contents, network, service that are required in production, modification, distribution, re-production of information. Convergence in contents started around 1990. Convergence in network and service begins as broadcasting and telecommunication integrates and DMB(digital multimedia broadcasting), born in May, 2005 is the symbolic icon in this trend. There are some positive and negative expectations about DMB. The reason why two opposite expectations exist is that DMB does not come out from customer's need but from technology development. Therefore, customers might have hard time to interpret the real meaning of DMB. Time is quite critical to a high tech product, like DMB because another product with same function from different technology can replace the existing product within short period of time. If DMB does not positioning well to customer's mind quickly, another products like Wibro, IPTV, or HSPDA could replace it before it even spreads out. Therefore, positioning strategy is critical for success of DMB product. To make correct positioning strategy, one needs to understand how consumer interprets DMB and how consumer's interpretation can be changed via communication strategy. In this study, we try to investigate how consumer perceives a new product, like DMB and how AD strategy change consumer's perception. More specifically, the paper segment consumers into sub-groups based on their DMB perceptions and compare their characteristics in order to understand how they perceive DMB. And, expose them different printed ADs that have messages guiding consumer think DMB in specific ways, either cellular phone or personal TV. Research Question 1: Segment consumers according to perceptions about DMB and compare characteristics of segmentations. Research Question 2: Compare perceptions about DMB after AD that induces categorization of DMB in direction for each segment. If one understand and predict a direction in which consumer perceive a new product, firm can select target customers easily. We segment consumers according to their perception and analyze characteristics in order to find some variables that can influence perceptions, like prior experience, usage, or habit. And then, marketing people can use this variables to identify target customers and predict their perceptions. If one knows how customer's perception is changed via AD message, communication strategy could be constructed properly. Specially, information from segmented customers helps to develop efficient AD strategy for segment who has prior perception. Research framework consists of two measurements and one treatment, O1 X O2. First observation is for collecting information about consumer's perception and their characteristics. Based on first observation, the paper segment consumers into two groups, one group perceives DMB similar to Cellular phone and the other group perceives DMB similar to TV. And compare characteristics of two segments in order to find reason why they perceive DMB differently. Next, we expose two kinds of AD to subjects. One AD describes DMB as Cellular phone and the other Ad describes DMB as personal TV. When two ADs are exposed to subjects, consumers don't know their prior perception of DMB, in other words, which subject belongs 'similar-to-Cellular phone' segment or 'similar-to-TV' segment? However, we analyze the AD's effect differently for each segment. In research design, final observation is for investigating AD effect. Perception before AD is compared with perception after AD. Comparisons are made for each segment and for each AD. For the segment who perceives DMB similar to TV, AD that describes DMB as cellular phone could change the prior perception. And AD that describes DMB as personal TV, could enforce the prior perception. For data collection, subjects are selected from undergraduate students because they have basic knowledge about most digital equipments and have open attitude about a new product and media. Total number of subjects is 240. In order to measure perception about DMB, we use indirect measurement, comparison with other similar digital products. To select similar digital products, we pre-survey students and then finally select PDA, Car-TV, Cellular Phone, MP3 player, TV, and PSP. Quasi experiment is done at several classes under instructor's allowance. After brief introduction, prior knowledge, awareness, and usage about DMB as well as other digital instruments is asked and their similarities and perceived characteristics are measured. And then, two kinds of manipulated color-printed AD are distributed and similarities and perceived characteristics for DMB are re-measured. Finally purchase intension, AD attitude, manipulation check, and demographic variables are asked. Subjects are given small gift for participation. Stimuli are color-printed advertising. Their actual size is A4 and made after several pre-test from AD professionals and students. As results, consumers are segmented into two subgroups based on their perceptions of DMB. Similarity measure between DMB and cellular phone and similarity measure between DMB and TV are used to classify consumers. If subject whose first measure is less than the second measure, she is classified into segment A and segment A is characterized as they perceive DMB like TV. Otherwise, they are classified as segment B, who perceives DMB like cellular phone. Discriminant analysis on these groups with their characteristics of usage and attitude shows that Segment A knows much about DMB and uses a lot of digital instrument. Segment B, who thinks DMB as cellular phone doesn't know well about DMB and not familiar with other digital instruments. So, consumers with higher knowledge perceive DMB similar to TV because launching DMB advertising lead consumer think DMB as TV. Consumers with less interest on digital products don't know well about DMB AD and then think DMB as cellular phone. In order to investigate perceptions of DMB as well as other digital instruments, we apply Proxscal analysis, Multidimensional Scaling technique at SPSS statistical package. At first step, subjects are presented 21 pairs of 7 digital instruments and evaluate similarity judgments on 7 point scale. And for each segment, their similarity judgments are averaged and similarity matrix is made. Secondly, Proxscal analysis of segment A and B are done. At third stage, get similarity judgment between DMB and other digital instruments after AD exposure. Lastly, similarity judgments of group A-1, A-2, B-1, and B-2 are named as 'after DMB' and put them into matrix made at the first stage. Then apply Proxscal analysis on these matrixes and check the positional difference of DMB and after DMB. The results show that map of segment A, who perceives DMB similar as TV, shows that DMB position closer to TV than to Cellular phone as expected. Map of segment B, who perceive DMB similar as cellular phone shows that DMB position closer to Cellular phone than to TV as expected. Stress value and R-square is acceptable. And, change results after stimuli, manipulated Advertising show that AD makes DMB perception bent toward Cellular phone when Cellular phone-like AD is exposed, and that DMB positioning move towards Car-TV which is more personalized one when TV-like AD is exposed. It is true for both segment, A and B, consistently. Furthermore, the paper apply correspondence analysis to the same data and find almost the same results. The paper answers two main research questions. The first one is that perception about a new product is made mainly from prior experience. And the second one is that AD is effective in changing and enforcing perception. In addition to above, we extend perception change to purchase intention. Purchase intention is high when AD enforces original perception. AD that shows DMB like TV makes worst intention. This paper has limitations and issues to be pursed in near future. Methodologically, current methodology can't provide statistical test on the perceptual change, since classical MDS models, like Proxscal and correspondence analysis are not probability models. So, a new probability MDS model for testing hypothesis about configuration needs to be developed. Next, advertising message needs to be developed more rigorously from theoretical and managerial perspective. Also experimental procedure could be improved for more realistic data collection. For example, web-based experiment and real product stimuli and multimedia presentation could be employed. Or, one can display products together in simulated shop. In addition, demand and social desirability threats of internal validity could influence on the results. In order to handle the threats, results of the model-intended advertising and other "pseudo" advertising could be compared. Furthermore, one can try various level of innovativeness in order to check whether it make any different results (cf. Moon 2006). In addition, if one can create hypothetical product that is really innovative and new for research, it helps to make a vacant impression status and then to study how to form impression in more rigorous way.

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광대역 위성 통신/방송용 삼중 대역 이동형 안테나 시스템 설계에 관한 연구 (A Study on Mobile Antenna System Design with Tri-band Operation for Broadband Satellite Communications and DBS Reception)

  • 엄순영;정영배;손성호;윤재승;전순익
    • 한국전자파학회논문지
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    • 제17권5호
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    • pp.461-475
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    • 2006
  • 본 논문은 Ka/K 통신 대역 및 Ku 방송 대역에서 동작하는 무궁화 3호 정지 궤도 위성을 이용하여 화상 전화, 인터넷과 같은 위성 멀티미디어 및 방송 서비스를 제공하는 이동체 탑재형 안테나 시스템 설계에 관한 것이다. 앙각 방향으로 팬 빔 특성을 갖는 안테나 시스템의 방사부는 준-오프셋 이중 성형 반사판과 삼중 대역 급전기로 구성된다. 또한, 삼중 대역 급전기는 돌출 유전체 막대를 이용한 Ka/K 이중 대역 급전기 및 원형 편파기, 직교 모드 변환기 그리고 Ku 대역 원형 편파 급전 배열로 구성된다. 특히, Ka/K 이중 대역 원형 편파기는 제작이 용이한 comb 구조를 사용하여 구현되었다. Ku 대역 급전 배열은 이동시 위성을 고속으로 추적하기 위하여 전자 빔을 형성할 수 있는 $2{\times}2$ 능동 위상 배열 구조를 갖는다. 그리고, 급전 배열에서 $90^{\circ}$ 하이브리드 결합기를 이용하여 원형 편파를 생성하는 4개의 방사 소자들을 $90^{\circ}$씩 회전하여 배열함으로써 원형 편파 특성을 개선하였다. Ku 대역 전자 빔을 생성하는 4개의 빔 성형 채널은 출력에서 주 빔 채널 및 추적 빔 채널로 구분되며, 각 채널의 내부 구성 유니트들의 잡음 온도 기여도를 바탕으로 채널 잡음 온도 특성을 분석하였다. 제작된 안테나 시스템으로부터 측정된 Ka 송신 채널의 $P_{1dBc}$ 출력은 34.1 dBm 이상, K/Ku 수신 채널의 잡음 지수는 각각 2.4 dB 및 1.5 dB 이하의 전기적인 성능들을 보여주었다. 안테나 시스템은 근접 전계 측정 방법을 사용하여 삼중 대역에서의 주 편파 및 교차 편파 방사 패턴들을 측정하였다. 특히, Ku 대역의 방사 패턴 측정은 급전 배열들의 독립 여기에 의한 부분 방사 패턴들을 측정하여 각 능동 채널들의 초기 위상들을 보정한 후 이루어졌다. 안테나 시스템의 Ka/K/Ku 대역에서 측정된 안테나 이득은 각각 39.6 dBi, 37.5 dBi, 29.6 dBi 이상이었으며, 그리고 Ka 대역 송신 EIRP는 43.7 dBW 이상, K/Ku 대역 수신 감도 G/T는 각각 13.2 dB/K와 7.12 dB/K 이상의 우수한 시스템 성능들을 보여주었다.

스마트 폰 기반 Self-Tour 서비스 기술 연구 (Self-Tour Service Technology based on a Smartphone)

  • 배경율
    • 지능정보연구
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    • 제16권4호
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    • pp.147-157
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    • 2010
  • 아이폰의 등장과 함께 스마트 폰에 대한 관심이 높아지고, 통신사업자를 통해야만 가능했던 다양한 서비스가 스마트 폰을 통해서 직접 제공할 수 있는 환경이 가능해졌다. 전세계적으로 해외 관광객이 증가하면서 관광가이드 없이 자신의 노력으로 여행을 다니는 개인관광객도 증가하고 있다. 그러나 우리나라를 방문하는 외국인들이 개인적으로 여행을 즐기기에는 언어소통이나 제공되는 정보의 부족으로 어려움을 느끼고 있다. 본 연구에서는 스마트 폰이 탑재하고 있는 GPS와 WiFi 또는 3G 무선망을 통해서 사전에 설정된 관광 정보 카테고리에 따라서 관광객의 위치에 따른 관련 정보를 자동으로 제공함으로써 관광객의 편의성을 높이는 서비스 기술을 개발하였다. 개발된 서비스는 인사동을 대상으로 시험하였으며, 사용자의 선택과 같은 불편함 없이 주변정보를 제공함으로써 관광에 대한 편의성을 최대한 높였다.