Earticle

인터넷TV 서비스 활성화로 인하여 아날로그 방송에서 디지털 방송으로 전환이 급속히 이루어지고 있으며, 인터넷TV는 서비스 특성상 네트워크, 채널 결합 신호방식(CAS, channel associated signaling) 등과 연동하여 서비스를 제공하고 있다. 이로 인해 IPTV 방송은 아날로그 방송에 비해 영상 지연현상 및 채널 전환 시간이 더 소요되며, 인터넷TV 서비스 사업자 및 STB(Set-Top Box) 제조업체에서는 채널전환 시간 최적화가 중요한 요소가 부각되고있다. 본 논문에서는 인터넷TV 실시간 방송 서비스에서의 채널전환 시간을 자동으로 측정하는 방법을 제시하고, 수동으로 측정한 채널 전환 측정 결과와 비교함으로써 제안 방법의 효과를 제시한다.

The transition from analog broadcasting to digital broadcasting is being made rapidly due to the activation of IPTV, and IPTV is providing service by linking with network and channel associated signaling(CAS). Therefore IPTV broadcasting has image delays and takes more time in channel transition, compared to analog broadcasting. Optimization in channel transition time is spotlighted as a critical factor for service licensees and set-top box (STB) manufacture industries. This paper proposes the method for automatically measuring the channel transition time in IPTV live broadcasting service, and compares with the result of manually measured channel transition time to show the effect of the proposed method.

디지털 압축 기술로 인한 방송 대역폭 증가 효과와 방송수신기의 영상처리기술 발달에 따라 디지털방송에 멀티 뷰 기능을 활용하는 연구 및 응용 개발이 진행되고 있다. 디지털방송에서의 멀티 뷰 기능은 시청자에게 서너 개의 방송프 로그램 영상을 동시에 시청할 수 있게 하거나 스포츠 방송의 경우 멀티 앵글 영상을 제공하여 원하는 시점에서 경기를 감상할 수 있도록 하는데 주로 응용되고 있는데 백 수십 개의 방송프로그램을 제공하고 있는 근래의 디지털방송 양상 을 반영하고 데이터서비스의 다양한 멀티 뷰 활용을 지원하는 통합적인 멀티 뷰 영상 지원 방법이 존재하지 않고 있다. 이 에, 본 논문은 디지털방송 사업자가 운영하는 모든 방송프로그램 영상들을 포함하는 멀티 뷰 영상을 구성하고 이를 데이터서비스가 활용할 수 있도록 DVB 표준에 정합되는 멀티 뷰 영상 활용 정보를 구성하고 전송하는 방식, 그리고 데이터서비스가 멀티 뷰 영상을 자신의 기능으로 수월하게 활용할 수 있도록 방송수신기의 미들웨어를 확장하는 방법 을 제안한다.

The development of the digital compression technology and the broadcasting receiver’s processing power make it possible to apply a multi-view function to the broadcasting services. The multi-view function is usually utilized to provide simultaneously several programs to viewers or to implement a multi-angle service of a sports program that allows a viewer to choose a video of his/her prefer viewpoint. The paper proposes an integrated method for utilizing a multi-view function in the digital broadcasting environment in which more than 100 programs are on air and there may be various data services which want to use multi-view video clips. For the purpose, a method of composing and transmitting multi-view videos and related information has been devised and a Java API to utilize the rapid editing function of a decoding chip-set has been implemented to clip, resize, and display parts of the multi-view videos.

실감미디어에 대한 시청자의 욕구가 증가하고 초고화질 방송을 위한 기술적 노력의 결과로 UHD(Ultra-High Definition) 방송시장의개시를 위한 움직임이 가속화되고 있다. 케이블 방송은 2013년 UHD 시범방송에 이어 2014년 4월 UHD 방송 상용화를 계획하고있다. 지상파 방송도 전송 규격에 대한 다양한 검토를 진행하며 2013년 2차례 실험방송을 실시하는 등 기술적 준비를 진행하고 있는상황이다. 하지만 아직 주파수 대역과 대역폭 등이 결정되지 않는 등 본격적인 서비스를 위해 해결할 과제가 남아있다. 이러한 배경에서 UHD 방송의 성공적인 개시와 방송시장의 활성화를 위해 본 논문은 차세대 지상파 방송을 위한 효율적인 주파수 운용 방안에대해 논의한다. 압축 부호기술과 채널 부호기술의 부호율 및 변조방식 등에 대한 고려를 통해 차세대 방송서비스를 위해 요구되는데이터 전송률을 검토하고, 시스템의 요구 대역폭을 제시한다. 또한 전국을 9개의 권역으로 나누고 SFN(Single FrequencyNetwork)망을 활용하여 4개의 주파수 군을 배분하는 안을 제시하였으며, 현재 사용하고 있는 지상파 디지털 주파수 대역을 재배치하여 지상파 UHD방송을 활성화하는 방안에 대해 제시한다.

Increasing demand for realistic media and improvement of transmission and device techniques accelerate ultra-highdefinition (UHD) service realization. In Korea, the cable TV broadcasting companies are planning to commercialize in Apr. 2014. For the terrestrial TV broadcasting service, technical issues are considered for the specification of UHD broadcastingsystem. However, the frequency bands and the system bandwidth for the terrestrial UHD broadcasting system have not beendecided. In this paper, we propose required spectrum bandwidth for the next-generation terrestrial broadcasting serviceconsidering source coding, error correcting codes and modulation techniques. Also, we propose frequency management planfor terrestrial UHD broadcasting system in which we divide all parts of the country into 9 frequency zones and allocate 4frequency band to each frequency zone considering single frequency network (SFN).

For the purpose of the Network in the home for multimedia service is one of the solution for delivery, processing, management and reuse of information. Home networking information devices in the home are required connection through wired and wireless network without time and location limitation. Normally, Home network system has been evolved using wired and wireless technologies to meet the technological requirement and installation cost. Home network system should be considered some kind of elements like multi physical layer and protocol support, security of QoS, transmission speed for multimedia service, easy to use at the existing premise and scalability.

Broadcasting system in the world has been changing rapidly analog into digital and most of the countries have plan to shutdown the analog system. Digital system has a high efficiency of bandwidth because it can easily do data compression. Service is being diversified and increased requirements of the data quality. In this reason data protection from hacker is most important for contents and data delivery system. In the broadcasting field, we called CAS system widely adopted for encryption and decryption of data and contents. Also, digital stream should be stored in the terminal for easy playback at once. DVR(Digital Video Recorder) is one of the important components of the broadcasting and IPTV terminals.

최근 STB 보급이 증가하면서 제품 출하 전 품질검사의 중요성이 부각되고 있다. 본 논문에서는 STB 영상 신호의 다채널 동시 입력을 통한 품질검사 자동화를 지원하기 위한 방법을 제안한다. 제안 방법은 먼저 색상 정보와 LDP 코드를 결합한 CeLDP를 이용하여 안정적인 비디오 샷 경계 검출 후 영상의 중앙 스캔라인을 이용한 핑거프린 트를 추출하여 입력 비디오 채널 간 동기화를 수행한다. 제안하는 방법은 기존 샷 검출 방법과 비교를 통해 더욱 강인한 샷 경계 검출 성능을 보이는 것을 확인하였으며, 실제 환경에 적용한 실험을 통해 STB 품질검사 시 필요한 다채널 입력 간 동기화를 위한 신뢰성 확보 및 실시간 품질검사가 가능함을 입증하였다. 또, 제안된 방법을 바탕으로 향후 대규모 품질검사 방법을 연구하여 보다 효과적인 품질검사 체계를 제안하고자 한다.

Recently, the importance of pre-shipment quality inspection has been emphasized due to the increase of STB supply. In this paper, we propose a method to support automation of quality inspection through simultaneous multi-channel input of STB video signal. The proposed method extracts a fingerprint using the center scan line of the image after stable video shot boundary detection using CeLDP combining color information and LDP code and performs synchronization between input video channels. The proposed method shows stronger shot boundary detection performance than the conventional shot detection method. Through the experiments applied to the real environment, it is possible to secure reliability and real-time quality check for synchronization between multi-channel inputs required for STB quality inspection. Also, based on the proposed method, we intend to study a large-scale quality inspection method in the future and propose a more effective quality inspection system.

본 연구는 개인화 클라우드 기반의 임베디드 STB(Set-Up Box) 적용을 통한 교육서비스 체계에 대한 연구로서 서버측에서는 개인화 클라우드 기반의 교육서비스 지원을 위한 서 비스 모델을 설계하고, 클라이언트 영역에서는 임베디드 STB를 기반으로 개인화 교육 콘 텐츠를 맞춤형으로 지원받아 IPTV 및 프로젝터를 통한 디스플레이가 가능하도록 지원하 는 교육용 제어보드를 개발하였다. 그리고 초중고 영어교실 및 방과후 수업에 적용이 가 능한 개인화 서비스 모델을 완성하고자 연구를 하였다. 또한 향후 이 서비스모델을 적용 하여 교사용 도우미 로봇에 제어용 보드로 활용이 가능하도록 확장성을 부여하고자 연구 하였다.

On the server side, the system for the education service of personalized cloud-based embedded STB (Set-Up Box) through the application of research as a research, design and support for the education service of personalized cloud-based service model based on the STB embedded in the client areapersonalized educational content received via IPTV and projector display customized support possible to support the educational development control board. School English classes and after-school classes in the personalized service model that can be applied to complete the study. Teacher assistant robot, the future service model by applying research to be used as the control board to grant scalability.

최근에 IPTV(Internet Protocol TV) 셋톱박스의 보조기억장치의 성능과 저전력을 위한 연구가 많이 수행 되고 있다. IPTV를 위한 셋톱박스의 구성품인 하드디스크는 멀티미디어 데이터를 저장하고 저장된 데이터를 재생한다. 하지만 하드디스크는 기계적인 특성으로 인하여 전력 소모 문제 및 성능 저하 문제 등이 있다. 본 논문에서는 IPTV 환경에서 하드디스크와 플래시 메모리를 혼합한 하이브리드 저장 시스템을 구성 하여 멀티미디어 데이터의 n-프레임을 플래시 메모리로 선반입 하는 새로운 방법을 제안한다. 이 방법을 통해 하드디스크의 대기시간을 줄이고 전력 사용을 최적화 할 수 있다. 실험을 통해 제안한 방법이 기존 방법과 비교하여 20.69%의 평균응답시간을 개선하고 전력소모를 28.14% 감소시킴을 확인 하였다.

최근에 IPTV(Internet Protocol TV) 셋톱박스의 보조기억장치의 성능과 저전력을 위한 연구가 많이 수행 되고 있다. IPTV를 위한 셋톱박스의 구성품인 하드디스크는 멀티미디어 데이터를 저장하고 저장된 데이터를 재생한다. 하지만 하드디스크는 기계적인 특성으로 인하여 전력 소모 문제 및 성능 저하 문제 등이 있다. 본 논문에서는 IPTV 환경에서 하드디스크와 플래시 메모리를 혼합한 하이브리드 저장 시스템을 구성 하여 멀티미디어 데이터의 n-프레임을 플래시 메모리로 선반입 하는 새로운 방법을 제안한다. 이 방법을 통해 하드디스크의 대기시간을 줄이고 전력 사용을 최적화 할 수 있다. 실험을 통해 제안한 방법이 기존 방법과 비교하여 20.69%의 평균응답시간을 개선하고 전력소모를 28.14% 감소시킴을 확인 하였다.

The use of CBN tool material has been greatil increased because of the superior metal cutting performance for the machining of hardened steels. This paper presents some experimental results on the ball endmilling of hardened steels. Three different hardnesses of STB-11 workpieces were machined using CBN ball endmills, and the machining charteristics including cutting forces, tool wear, and surface roughness of machined surface were compared. It has been found that the CBN ball endmill works better in the machining of harder workpieces. The microscopic examination explains that this unusual phenomenon is cause by the difference of microstructure of each workpieces.

It has been very important in various industry fields to improve the fatigue strength characteristics of bearings such as bearing life, fatigue limit, etc., because such poor properties could result in shortening the machinery life as well as in decreasing the accuracy. However, no successful heat treatment criterion seems to be available at present. In this study, the effect of the $170^{\circ}C\times120min$ tempering cycles repeated after $380^{\circ}C\times80min$ oil quenching for $800^{\circ}C$ spheroidizing-annealed bearing steel (STB2) as base metal on the $120^{\circ}C$ high temperature rotary bending fatigue strength characteristics were investigated, including the effects on hardness, Charpy impact value and micro-structure, in order to seek for the best heat treatment condition finally. The important results obtained are as follows : 1) The optimal cycle of tempering so that the fatigue strength .sigma. could become the highest was the 4th cycle. And it is confirmed that this $\sigma_{F}$ is about 6 times more increased than that of base metal, and about 1.3 times more increased than the case of the 1 cycle tempered. 2) As a result of the investigation for the effects of tempering cycles on hardness, the hardness at the tempering number of 2 thru 5 cyles was not decreased severely ; only about 10% decrease from those of the quenched and 1 cycle tempered case. Such hardness is equivalent to $H_{R}$/C61-62 with no bad effect on anti-abrasion of bearing steel. 3) In the case of 2 thru 5 cycle tempering as well as 1 cycle tempering, the impact value was not so improved comparing with the case of quenching, but an increase of 5 to 10% could be expected at least. 4) It was experimentally confirmed that the control of the mechanical properties improvement such as fatigue strength and fatigue life for bearing steels could be possible by the number of tempering cycles.

This study was performed to evaluate repeated-dose toxicities of STB-HO-BM in Sprague-Dawley rats. STB-HO-BM was administered orally to rats at dose levels of 0, 100, 300 and 1,000 mg/kg/day for 13 weeks. In recent study, there were no dose related changes in mortality, clinical signs, body weight changes, food and water consumption, opthalmoscopy, organ weights, urine analysis, hematological findings, and biochemical examination of all animals treated with STB-HO-BM. Gross and histopathological findings revealed no evidence of specific toxicity related to STB-HO-BM. These results suggest that the oral no observed adverse effect level (NOAEL) of STB-HO-BM may be over 1,000 mg/kg in rats.

The acute toxicity of STB-HO-BM was evaluated in Sprague Dawley (SS) rats and beagle dogs. STB-HO-BM was administered orally to rats at dose levels of 0 and 2,000mg/kg/day and to dogs at dose levels of 0, 500, 1,000 and 2,000 mg/kg/day. In these experiments, there were no death and clinical changes which were related to STB-HO-BM administration. In addition, there were no significant changes between control and treated groups in body weights and autopsy findings. In conclusion, the administration of STB-HO-BM 2,000 mg/kg in SD rats and up to 2,000mg/kg in beagle dogs was proved to be safe, and it is thought that STB-HO-BM may not show any toxicity in its clinical use.

We have investigated the genotoxicity of STB-HO-BM using in vitro and in vivo system such as Ames reverse mutation test, chromosomal aberration test and micronucleus test. in Ames reverse mutation test, STB-HO-BM treatment at the dose range up to 5,000 ug/plate did not induce mutagenicity in Salmonella typhimurium TA98, TA100, TA102, TA1535, TA 1537 and in Escherichia coli WP2 uvrA with and without metabolic activation. Any significant aberration wasn't observed in chinese hamster lung (CHL) fibroblast cells treated with STB-HO-BM at the concentration of 12.5, 2.5, 5 mg/ml both in the absense and presence of metabolic activation system. In mouse micrnucleus test, no significant increase in the occurrence of micronucleated polychromatic erythrocytes was observed in ICR male mice orally administered with STB-HO-BM at the doses of 0.5, 1.0, 2.0 g/kg. These results indicate that STB-HO-BM has no mutagenic potential under the condition in this study.

The present study was undertaken to investigate the dry wear mechanism of the alumina ceramics in the purity variation for the wear of STB2. The wear test was carried out under different experimental condition various sliding speed, contact pressure and sliding distance. According as the alumina purity increased, wear volume of the STB2 decreased and minimum value of wear volume was over to high speed side. According as the sliding speed and sliding distance increased, friction coefficient decreased owing to drop of the shear strength, it decresed largely owing to decreased of elastic modulus and thermal conductivity with decrease in alumina purity. Indicative of minimum, value of wear volume, low speed side was abrasive wear, high speed side was wear of heat softening. The friction surface of ceramics protacted by oxide was transfer from STB2.

With the development of the industry, bearings that require higher durability and efficiency are required, and various methods to reduce friction and wear of bearings are being studied. In this study, a wear test was conducted for STB2, a bearing steel material, by machining a micro-line pattern on the race surface of the bearing by machining. The pattern pitch of the specimens was processed to 40㎛, 80㎛, and 150㎛, and the coefficient of friction characteristics were investigated for the unpatterned specimen and the specimen with a DLC thin film deposited on the surface. As a result of the wear test, the pattern pitch showed the smallest coefficient of friction at 40㎛, and it was confirmed that the smaller the pattern pitch, the better the tribology characteristics.