• 기술혁신학회지
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• 제1권3호
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• pp.386-401
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• 1998

Videophone service was developed and marketed by AT&T in the late 1960s and early 1970s. The market did not respond to the service offering, and the service was withdrawn. However, Videophone returned in the late 1980s and early 1990s. Due to the technological advance, establishment of ITU standards and fall of videophone price, many analysts are very optimistic about videophone market. But on the other hand, some analysts anticipate that recent videophone will only replicate the past with the same results: namely, market failure. First, this article reviews the history of videophone service, the recent development trend and reasons for its market failure. Second, this article reviews prospects for videophone service. Finally authors examine some of the technological and service features that might shift the value of videophone service.

• 정보처리학회논문지D
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• 제16D권2호
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• pp.281-294
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• 2009

본 연구는 TAM(Technology Acceptance Model)를 이용하여 모바일 영상통화서비스의 지속적인 사용에 영향을 미치는 요인들을 분석하였다. SPSS 12.0을 이용한 데이터 분석 결과는 인지된 유용성, 인지된 사용용이성, 영상통화 품질, 집중, 주변인의 영상통화 이용정도가 지속적인 모바일 영상통화서비스 이용에 유의한 영향을 미치는 것으로 나타났다. 그러나 조절효과로서 주변인의 영상전화기 보유와 이용 정도, 요금, 품질, 프라이버시와 지속적 이용간의 관계는 모두 유의하지 않는 것으로 나타났다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.617-618
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• 2008

The paper describes the design and implementation of full-software videophone module for Korean Government's Ubiquitous Robotic Companion project 2007. The project shows the commercial feasibility of video service, particularly videophone service with 3G WCDMA cellular mobile phone.

• 정보와 통신
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• 제11권8호
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• pp.60-77
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• 1994

This paper presents a survey of video coding schemes which use wavelet transform for the videophone on very low bit rate commun ication chan nel( ego 10 Kbps Public Service Telephone Network). Firstly, we introduce the standardization efforts to make the low bit rate videophone architecture and the typical application of low bit rate video coding scheme. Secondly, we summarize the several requirements on videophone, delay, encoder/decoder complexity, low bitrate, and progressive transmission capability. Third, we review the basic theory of wavelet transform without much mathematics. We compare the wavelet transform with short-time fourier transform and subband filters. Fourth, we summarize the video coding schemes proposed so far, and evaluate them with Ule requirements. Lastly, we conclude with fu¬ture research directions.

• 한국통신학회논문지
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• 제25권12B호
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• pp.2109-2119
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• 2000

In this paper, the Packet CDMA Reservation ALOHA protocol is proposed to support the multi-traffic services such as voice and videophone services with handoff calls, high-rate data and low-rate data services efficiently on the multi-rate transmission in uplink cellular systems. The frame structure, composed of the access slot and the transmission slot, and the proposed access permission probability based on the estimated number of contending users for each service are presented to reduce MAI. The assured priority to the voice and the videophone handoff calls is given through higher access permission probability. And through the proposed code assignment scheme, the voice service can be provided without the voice packet dropping probability in the CDMA/PRMA protocols. The code reservation is allowed to the voice and the videophone services. The low-rate data service uses the available codes during the silent periods of voice calls and the remaining codes in the codes assigned to the voice service to utilize codes efficiently. The high-rate data service uses the assigned codes to the high-rate data service and the remaining codes in the codes assigned to the videophone service. Using the Markov-chain subsystem model for each service including the handoff calls in uplink cellular systems, the steady-state performances are simulated and analyzed. After a round of tests for the examples, through the proposed code assignment scheme and the access permission probability, the Packet CDMA Reservation ALOHA protocol can guarantee the priority and the constant QoS for the handoff calls even at large number of contending users. Also, the data services are integrated efficiently on the multi-rate transmission.

• 로봇학회논문지
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• 제6권2호
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• pp.147-155
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• 2011

This paper presents an edutainment robot for young children. The edutainment robot called 'Mon-e' has developed by the Central R&D Laboratory at KT. The main services of the Mon-E robot are autonomous moving service, object card and story book telling service and videophone service. The RFID technology was introduced for easy interface to young children. The face of Mon-E robot is mounted with an RFID reader. The RFID tag is pasted on story book and object card. If you approach a book or an object card to the face of Mon-E, the Mon-E robot recognizes the identified code and plays its service. In autonomous moving, if the Mon-E robot meets obstacles, it moves back and turns left or right or half rotation. In videophone service, if young children approach an RFID card to the Mon-E, the Mon-E can make a call to the specific number, which is contained in the RFID card. The developed Mon-E robot has tested in real world environment and is evaluated young children and their parents. In the result of evaluation, the feeling of satisfaction was high to main services of Mon-E robot.

• 전자공학회논문지A
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• 제33A권5호
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• pp.155-164
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• 1996

The architecture of a programmable video codec IC is described that employs multiple vector processors in a single chip. The vector processors operate in parallel and communicate with one another through on-chip shared memories. A single scalar control processor schedules each vector processor independently to achieve real-tiem video coding with special vector instructions. With programmable interconnection buses, the proposed architecture performs multi-processing of tasks and data in video coding. Therefore, it can provide good parallelism as well as good programmability. especially, it can operate multithread video coding, which processes several independent image sequences simultaneously. We explain its scheduling, multithred video coding, and vector processor architectures. We implemented a prototype video codec with a 0.8um CMOS cell-based technology for the multi-standard videophone. This codec can execute video encoding and decoding simultaneously for the QCIF image at a frame rate of 30Hz.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.453-456
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• 2000

This paper describes IMT-2000 Testbed System which consists of ATM based IMT-2000 exchange(A-lMX), RNC simulator, HLR simulator, SCP simulator, B-ISDN subscriber simulator and MS simulator. Simulators were developed to verify the mobile functions and basic services of IMT-2000 like Videophone, VoD(Video on Demand), and Internet access. UPT(Universal Personal Telecommunication) service could be adapted well to this testbed system. Until the entire network elements are developed fully, this testbed system can be used to prove new services in IMT-2000 network.

• 한국정보처리학회논문지
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• 제7권7호
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• pp.2041-2049
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• 2000

A various multimedia application services are developed wiht techniques of high speed networks and computer. Especially the videoconference system is important and useful in a remote discussion with multiple users. A vidoconferencing system in local area network used in corporation and university is useful and important. A standardization for it should be showed in ITU. Recommendation H.323 describes terminals, equipment, and services for videoconference over communication networks which do not provide a guaranteed Quality of Services for videoconference over communication networks which do not provide a guaranteed Quality of Service. In this paper, we introduce ITU-T H.323 which is the standardization over internet, and show a multipoint videoconferencing system and peer to peer videophone system using the ITU-T H.323.

• 한국통신학회논문지
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• 제31권3C
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• pp.245-249
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• 2006

일반적으로 H.264/AVC 압축 표준의 CAVLC 복원 기법에 있어서 많은 횟수의 메모리 액세스가 요구되어진다. 그런데 이것은 상당한 전력 소모를 가져오기 때문에 DMB 및 비디오폰 서비스에 있어서 큰 문제가 된다. 이러한 문제를 해결하기 위하여 본 논문에서는 효율적인 run_before 복원 방식을 제안한다. 제안 방식에서는 산술 연산으로 구성된 FSM 기법을 토대로 하여 복호화시에 야기되는 메모리 액세스가 제거된다. 모의 실험 결과는 제안 방식에 의하여 화질의 손실이 발생하지 많으며 시스템 Power가 절약됨을 보여준다.