• 제목/요약/키워드: Multimedia message

검색결과 271건 처리시간 0.022초

다중 언폴딩 기법을 이용한 SHA-1 해쉬 알고리즘 고속 구현 (Implementation of High-Throughput SHA-1 Hash Algorithm using Multiple Unfolding Technique)

  • 이은희;이제훈;장영조;조경록
    • 대한전자공학회논문지SD
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    • 제47권4호
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    • pp.41-49
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    • 2010
  • 본 논문은 다중 언폴딩 기법을 이용한 고속 SHA-1 해쉬 알고리즘 구현 방법을 제시하였다. 제안된 SHA-1 해쉬 구조는 알고리즘의 반복적인 단계 연산을 언폴딩한 후 연산의 순서를 재 배열하고, 임계경로에 포함된 연산의 일부를 이전 단계에서 선행연산하여 임계경로의 길이를 줄였다. 제안된 SHA-1 해쉬 구조는 최대 118 MHz의 동작주파수에서 5.9 Gbps 처리량을 나타낸다. 이는 기존의 SHA-1 보다 전송량이 26% 증가하였고, 회로 크기가 32% 감소하는 결과를 얻었다. 또한 이 논문에서는 여러 개의 SHA-1 모듈을 시스템 레벨에서 병렬로 연결하여 여러 개의 SHA-1을 다중 처리하여 고속화를 할 수 있는 모델을 제안했다. 이 모델은 하나의 SHA-1을 사용하는 것보다 빠르게 데이터를 처리할 수 있고 입력되는 데이터의 최소한의 지연으로 처리 가능하다. 제안된 모델은 입력되는 데이터가 지연 없이 처리 되도록 하기 위해 필요로 하는 SHA-1의 FPGA 수를 구할 수도 있다. 고속화된 SHA-1은 압축된 메시지에 유용하게 사용될 수 있고 모바일 통신이나 인터넷 서비스 등의 강한 보안에 널리 이용가능하다.

효율적인 자바언어 학습을 위한 인터넷기반 자율학습시스템의 구현 (An Internet-based Self-Learning Educational System for Efficient Learning of Java Language)

  • 김동식;이동엽
    • 공학교육연구
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    • 제8권1호
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    • pp.71-83
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    • 2005
  • 본 논문에서는 자바 언어를 학습하는데 있어 효율성을 증가시키기 위해 인터넷 기반 자율학습시스템이 제안되었다. 제안된 자율학습시스템은 JWP(Java Web Player)라고 불리며 Java Web Start 기술을 활용하여 웹상에서 실행이 가능한 자바 애플리케이션 프로그램이다. 또한 본 논문에서는 컴퓨터 언어를 학습하는데 있어 3가지 중요한 일련의 과정인 개념학습과정, 프로그래밍 실습과정, 그리고 학습 성취도 평가과정을 Java Web Start 기술을 이용하여 JWP에 통합하였다. 제안된 시스템은 학습과정을 교육공학적인 측면에서 멀티미디어 요소를 강화하였기 때문에 학습자가 흥미를 가지고 자발적으로 학습을 할 수 있도록 설계되었다. 더욱이 JWP 에는 효율적인 자바 언어 학습을 위해 학습내용에 대한 설명이 음성으로 출력되며, 이때 이와 관련된 이미지와 텍스트들이 동기화되어 동시에 화면에 표시된다. 더욱이 소스파일의 코딩, 에디팅, 실행 그리고 디버깅 등을 쉽게 할 수 있는 컴파일러가 삽입되어 있어 편리한 자바 언어 실습환경을 제공한다. 마지막으로 각 단원별 돌발퀴즈와 마무리 테스트를 통하여 학습자가 자신의 학습상황을 체크하여 반복학습을 할 수 있도록 유도하였다.

IT서비스의 품질평가 모델 : 이동통신 서비스의 품질 구성요소를 중심으로 (A Study on the Evaluation Model of IT Service Quality: concentrated on the Quality Components in Mobile Communication Service)

  • 심종섭
    • 산학경영연구
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    • 제17권2호
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    • pp.203-228
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    • 2004
  • 이 논문은 IT서비스의 품질평가 모델을 개발하는 것을 목적으로 한다. 접근방법은 이동통신 서비스(휴대폰)의 품질평가 요소들을 중심으로 조사연구를 하였다. 오늘날 이동통신 서비스 산업은 날로 발전하고 있고 소비자 역시 새로운 제품품질에 대한 욕구가 다양화되고 있어 다기능, 다매체서비스, 고속데이터 전달서비스 등 다양한 부가서비스의 새로운 경쟁시대에 직면하고 있다. 이 연구에서 얻어진 결과는 이동통신 서비스의 전반적인 품질 결정요인으로 (1) 통화품질, (2) 휴대폰단말기, (3) 지원서비스, (4) 부가서비스, (5) 지원시설 및 설비, (6) 비용이 유의한 영향을 미치고 있고, 이동통신 서비스의 본원적 기능인 통화품질에 추가하여 휴대폰 단말기와 부가서비스들이 중요한 영향을 미치는 것으로 나타났다. 한편 휴대폰 단말기와 부가서비스 요소는 이동통신 서비스의 전반적 품질결정에 직접적으로 영향을 미칠 뿐만 아니라, 고객만족에도 직접적으로 영향을 미치는 요소로 확인되었다. 이는 소비자들이 직접 휴대하고 이용하는 단말기와 부가서비스가 매우 중요하다는 사실을 다시 한 번 확인해주는 것으로 보인다.

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영상 처리를 이용하여 주변 환경 센서를 관리하기 위한 유비쿼터스 홈 네트워크 시스템 (A Ubiquitous Home Network System for Managing Environment-Information Sensors using Image Processing)

  • 홍성화;정석용
    • 한국산학기술학회논문지
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    • 제11권3호
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    • pp.931-942
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    • 2010
  • 홈 네트워크는 사용자에게 많은 정보서비스를 제공하여 준다. 특히, 다양한 센서 데이터를 활용함으로써 그 서비스의 종류와 질을 풍부하게 한다. 하지만 홈네트워크는 현재 멀티미디어 서비스에 집중함으로써 그 서비스의 활용폭을 스스로 제한하고 있는 실정이다. 특히 댁내 통신망에 집중함으로써 실내의 여러 가전기기를 제어하는 데는 많은 성과를 얻고 있으나 실외의 여러 기기를 제어하는 데는 큰 성과가 나오지 않고 있다. 실외의 여러 기기는 실내의 가전기기와 다르게 특정 기능을 강조하는 형태로 구성되는 경우가 많기 때문에 여러 기능을 가진 센서보다는 한 두가지 기능을 가진 센서를 활용하여 시스템을 구성하면 되기 때문에 실내에서 센서 노드를 사용하는 것보다 훨씬 경제성도 높다고 할 수 있다. 본 논문에서는 현재 가장 많은 사용 목적을 가진 여러 가지 기능 중 동작 센서를 선택하여 이를 활용할 시스템으로 주차장 관리 시스템을 선택하여 이를 홈 네트워크에 접목하여 구현하여 보았다.

학습자 참여를 유도하기 위한 얼굴인식 기반 지능형 e-Learning 시스템 (Intelligence e-Learning System Supporting Participation of Students based on Face Recognition)

  • 배경율;정진우;민승욱
    • 지능정보연구
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    • 제13권2호
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    • pp.43-53
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    • 2007
  • e-Learning 시스템은 원격지에 위치하여 학습자의 원격교육 및 멀티미디어 교육을 지원할 수 있는 차세대 교육 기술로 주목받고 있다. 그러나 학습자가 원격지에 위치하기 때문에 학습일탈 여부나 다수의 학습자에 대한 확인이 어려운 문제점을 안고 있어 이러한 문제점들에 대처하기 위하여 실시간 동영상 전달을 통한 학습자의 감시나 실시간 메시지 교환과 같은 대안들이 시도되고 있다. 반면에 이러한 대안들은 학습자의 인권 침해 소지와 다중 사용자의 영상 전달이라는 측면에서 시스템에 커다란 비용을 초래하게 되며, 수시로 전달되는 메시지는 학습의 효과를 반감시킬 수 있다. 따라서 학습자의 상태를 실시간으로 확인하는 동시에 시스템의 비용을 줄일 수 있는 방안으로 얼굴인식기술 기반의 지능형 시스템을 제안하고자 한다. 웹 상에서 이뤄지는 얼굴인식 기반 지능형 e-Learning 시스템은 학습자가 지속적으로 교육에 집중하는 동안 학습자의 얼굴을 이용해 학습일탈 여부를 확인하고, 확인된 학습자의 얼굴 영상은 중앙에서 학습자를 지도하는 교수에게 통보하게 된다. 본 시스템의 실험을 위하여 20명의 학습자와 1명의 교수가 각각 원격지에 위치한 PC를 사용하여 얼굴 등록 및 인식에 참여하였으며, 학습자의 일탈 방지 및 인식 성공을 위한 주의력 향상의 결과를 얻을 수 있었다.

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Effects of Foodservice Franchise's Online Advertising and E-WOM on Trust, Commitment and Loyalty

  • AHN, Sung-Man;YANG, Jae-Jang
    • 한국프랜차이즈경영연구
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    • 제12권2호
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    • pp.7-21
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    • 2021
  • Purpose: One of the characteristics of service companies such as foodservice franchise is that it is easy to imitate, so many brands can imitate the menu that is popular with consumers. Therefore, foodservice franchise company should develop a brand that customers can identify from other brands in order differentiate it from its competitors. In order make the foodservice franchise company identifiable from other brands, it is possible through communication with customers. Therefore, this study proposes a new research model to analyze customer loyalty through online advertising and online word of mouth trust and immersion. Online was provided to customers through a mixture of advertisements and word of mouth, but previous studies have only considered online advertisements or online word of mouth. In addition, we want to verify the difference according to gender, which is an important variable in researching the online information processing behavior of customers. Research design, data, and methodology: The questionnaire of this study was surveyed on 20 years of age or older who have visited the restaurant franchise store within the last 3 months among the foodservice franchise companies operating SNS. During the survey period, 400 surveys were surveyed for a total of 20 days from April 1 to April 20, 2020. Result: The research results are as follows. First, in this study, the effect of online advertisement and online word of mouth on trust and immersion was studied. Second, this study verified the social influence theory in online advertising and online word of mouth. Third, the effect of online advertising and online word of mouth on loyalty according to gender was verified. Fourth, compared to existing advertisements, online advertisements are suitable for marketing by foodservice franchise companies because they can interact with consumers, modify advertisements immediately, execute extensive advertisements at low cost, segment the market, and measure advertisement effectiveness. The recent online expansion has been expanded to mobile-based, allowing foodservice franchisees to provide new communication services such as SMS (Short Message Service), multimedia messaging services, and location-based services. Fifth, a foodservice franchise company can increase brand awareness through online marketing or induce the use of offline stores. Sixth, franchisor can grow into a sustainable company only when they use resources efficiently. Conclusions: Trust is important in foodservice franchise information. This trust has a significant impact on customer commitment and loyalty.

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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미술교육에 있어서 시각적 미디어를 통한 조형교육에 관한 연구 (Visual Media Education in Visual Arts Education)

  • 박지숙
    • 조형예술학연구
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    • 제7권
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    • pp.64-104
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    • 2005
  • Visual media transmits image and information reproduced in large quantities, such as a photography, film, television, video, advertisement, or computer image. Correspondence to the students' reception and recognition of culture in the future. arrangements for the field of studies of visual culture. 'Visual Culture' implies cultural phenomena of visual images via visual media, which includes not only the categories of traditional arts like a painting, sculpture, print, or design, but the performance arts including a fashion show or parade of carnival, and the mass and electronic media like a photography, film, television, video, advertisement, cartoon, animation, or computer image. In the world of visual media, Image' functions as an essential medium of communication. Therefore, people call the culture of today fra of Image Culture', which has been converted from an alphabet convergence era to an image convergence one. Image, via visual media, has become a dominant means for communication in large part of human life, so we can designate an Image' as a typical aspect of visual culture today. Image, as an essential medium of communication, plays an important role in contemporary society. The one way is the conversion of analogue image like an actual picture, photograph, or film into digital one through the digitalization of digital camera or scanner as 'an analogue/digital commutator'. The other is a way of process with a computer drawing, or modeling of objects. It is appropriate to the production of pictorial and surreal images. Digital images, produced by the other, can be divided into the form of Pixel' and form of Vector'. Vector is a line linking the point of departure to the point of end, which organizes informations. Computer stores each line's standard location and correlative locations to one another Digital image shows for more 'Perfectness' than any other visual media. Digital image has been evolving in the diverse aspects, such as a production of geometrical or organic image compositing, interactive art, multimedia art, or web art, which has been applied a computer as an extended trot of painting. Someone often interprets digitalized copy with endless reproduction of original even as an extension of a print. Visual af is no longer a simple activity of representation by a painter or sculptor, but now is intimately associated with a matter of application of media. There is some problem in images via visual media. First, the image via media doesn't reflect a reality as it is, but reflects an artificial manipulated world, that is, a virtual reality. Second, the introduction of digital effect and the development of image processing technology have enhanced a spectacle of destructive and violent scenes. Third, a child intends to recognize the interactive images of computer game and virtual reality as a reality, or truth. Education needs not only to point out an ill effect of mass media and prevent the younger generation from being damaged by it, but also to offer a knowledge and know-how to cope actively with social, cultural circumstances. Visual media education is one of these essential methods for the contemporary and future human being in the overflowing of image informations. The fosterage of 'Visual Literacy' can be considered as a very purpose of visual media education. This is a way to lead an individual to the discerning, active consumer and producer of visual media in life as far as possible. The elements of 'Visual Literacy' can be divided into a faculty of recognition related to the visual media, a faculty of critical reception, a faculty of appropriate application, a faculty of active work and a faculty of creative modeling, which are promoted at the same time by the education of 'visual literacy'. In conclusion, the education of 'Visual Literacy' guides students to comprehend and discriminate the visual image media carefully, or receive them critically, apply them properly, or produce them creatively and voluntarily. Moreover, it leads to an artistic activity by means of new media. This education can be approached and enhanced by the connection and integration with real life. Visual arts and education of them play an important role in the digital era depended on visual communications via image information. Visual me야a of day functions as an essential element both in daily life and in arts. Students can soundly understand visual phenomena of today by means of visual media, and apply it as an expression tool of life culture as well. A new recognition and valuation visual image and media education is required to cultivate the capability of active, upright dealing with the changes of history of civilization. 1) Visual media education helps to cultivate a sensibility for images, which reacts to and deals with the circumstances. 2) It helps students to comprehend the contemporary arts and culture via new media. 3) It supplies a chance of students' experiencing a visual modeling by means of new media. 4) There are educational opportunities of images with temporality and spaciality, and therefore a discerning person becomes to increase. 5) The modeling activity via new media leads students to be continuously interested in the school and production of plastic arts. 6) It raises the ability of visual communications dealing with image information society. 7) An education of digital image is significant in respect of cultivation of man of talent for the future society of image information as well. To correspond to the changing and developing social, cultural circumstances, and the form and recognition of students' reception of them, visual arts education must arrange the field of studying on a new visual culture. Besides, a program needs to be developed, which is in more systematic and active level in relation to visual media education. Educational contents should be extended to the media for visual images, that is, photography, film, television, video, computer graphic, animation, music video, computer game and multimedia. Every media must be separately approached, because they maintain the modes and peculiarities of their own according to the conveyance form of message. The concrete and systematic method of teaching and the quality of education must be researched and developed, centering around the development of a course of study. Teacher's foundational capability of teaching should be cultivated for the visual media education. In this case, it must be paid attention to the fact that a technological level of media is considered as a secondary. Because school education doesn't intend to train expert and skillful producers, but intends to lay stress on the essential aesthetic one with visual media under the social and cultural context, in respect of a consumer including a man of culture.

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RSA의 오일러 함수 𝜙(n) 해독 2kβ 알고리즘 (A 2kβ Algorithm for Euler function 𝜙(n) Decryption of RSA)

  • 이상운
    • 한국컴퓨터정보학회논문지
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    • 제19권7호
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    • pp.71-76
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    • 2014
  • 대표적인 공개키 암호방식인 RSA에 사용되는 합성수 n=pq의 큰자리 소수 p,q를 소인수분해하여 구하는 것은 사실상 불가능하다. 공개키 e와 합성수 n은 알고 개인키 d를 모를 때, ${\phi}(n)=(p-1)(q-1)=n+1-(p+q)$을 구하여 $d=e^{-1}(mod{\phi}(n))$의 역함수로 개인키 d를 해독할수 있다. 따라서 ${\phi}(n)$을 알기위해 n으로부터 p,q를 구하는 수학적 난제인 소인수분해법을 적용하고 있다. 소인수분해법에는 n/p=q의 나눗셈 시행법보다는 $a^2{\equiv}b^2(mod\;n)$, a=(p+q)/2,b=(q-p)/2의 제곱합동법이 일반적으로 적용되고 있다. 그러나 다양한 제곱합동법이 존재함에도 불구하고 아직까지도 많은 RSA 수들이 해독되지 않고 있다. 본 논문은 ${\phi}(n)$을 직접 구하는 알고리즘을 제안하였다. 제안된 알고리즘은 $2^j{\equiv}{\beta}_j(mod\;n)$, $2^{{\gamma}-1}$ < n < $2^{\gamma}$, $j={\gamma}-1,{\gamma},{\gamma}+1$에 대해 $2^k{\beta}_j{\equiv}2^i(mod\;n)$, $0{\leq}i{\leq}{\gamma}-1$, $k=1,2,{\ldots}$ 또는 $2^k{\beta}_j=2{\beta}_j$${\phi}(n)$을 구하였다. 제안된 알고리즘은 $n-10{\lfloor}{\sqrt{n}}{\rfloor}$ < ${\phi}(n){\leq}n-2{\lfloor}{\sqrt{n}}{\rfloor}$의 임의의 위치에 존재하는 ${\phi}(n)$도 약 2배 차이의 수행횟수로 찾을 수 있었다.

지상파 DMB를 이용한 클립캐스트 서비스 설계 및 구현 (Design and Implementation of Clipcast Service via Terrestrial DMB)

  • 조석현;서종수
    • 방송공학회논문지
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    • 제16권1호
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    • pp.23-32
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    • 2011
  • 본 논문에서는 지상파 DMB를 이용하여 동영상, mp3, 텍스트, 정지영상 등 파일의 일부분인 클립을 전송하고 단말기에서 수신하는 클립캐스트 서비스를 위한 시스템 설계를 제안하고 구현하였다. 지상파 DMB 클립캐스트를 위해서는 데이터 채널의 별도 할당이 필요하며 이를 위해서는 기존 대역의 재조정이 필요하다. 클립캐스트는 지상파 DMB 시청이 적은 심야시간 (03:00~04:00)에 콘텐츠를 전송하며 비디오 서비스의 비트율을 352 Kbps로 낮추고 TPEG 서비스 대역을 이용하면 320 Kbps의 비트율로 클립캐스트 전송이 가능하다. 또한 단말기의 DMB 프로그램 구동을 위해 SMS(Short Message Service) 구동 방식과 EPG(Electronic Program Guide) 구동방식을 제안하였다. 클립캐스트 서비스는 멀티미디어 객체를 전송하는 MOT 프로토콜을 이용하며 파일의 안정적인 전송을 위하여 카루젤 형태로 2번 반복하여 전송한다. 이럴 경우 1시간 동안 전송 가능한 데이터 용량은 72 Mbyte로서, 500 Kbps급의 동영상을 시청할 경우 약 20분 정도의 동영상 서비스가 가능하다. 지상파 DMB 데이터 채널로 전송되는 클립을 표출할 때에는 CMS(Content Management Server)와 통신하여 각 클립의 길이에 대한 정보를 전달받은 후, 에러 없이 전송된 파일에 대해서만 표출해 준다. 각 콘텐츠는 사용자에게 미리보기 형식으로 제공이 가능하고 해당 콘텐츠 전체를 이용하기 위해서는 해당 콘텐츠에 할당된 URL로 접속하여 과금 과정을 거친 후 콘텐츠 다운로드가 가능하게 된다. 본 논문에서는 클립캐스트 서비스를 위한 지상파 DMB 시스템 설계를 제안하고 이를 구현함으로써 MediaFLO, DVB-H 등 타 모바일 방송에서 서비스하고 있는 파일 다운로드 서비스의 구현이 가능하게 되었다. 클립캐스트 서비스를 위한 단말기의 구동으로 타 모바일 방송에서는 EPG 구동 방식만 구현한데 비해 본 시스템에서는 EPG 보다 수신 신뢰성이 높은 SMS를 이용한 구동 방식을 제안함으로써 보다 안정된 서비스 제공이 가능하게 되었다. 이에 따라 클립캐스트 서비스에서 SMS와 EPG를 같이 이용하여 단말기를 구동시키는 하이브리드 구동 방식도 가능하게 되었다.