• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.203-206
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• 2005

차량 진단 기능이 탑재된 원격 서버, 제어 신호 중계 기능을 가진 휴대폰용 어플리케이션, 그리고 신호 변환을 위한 converting 보드를 사용하여 기존의 차량진단기(scanner)와 동일한 기능을 가지는 원격차량진단 시스템을 제안한다. 원격 서버에서 직접 차량 진단 기능을 수행함으로써 진단 이력에 대한 자동 관리가 가능하며 다양한 부가 서비스를 연계하여 제공할 수 있다. 또한 신규 차종에 대하여 원격 서버 프로그램의 변경으로 대응이 가능하므로 기존 방식처럼 신규 차종에 대한 개별 upgrade가 필요 없다. 제안한 방식은 저가의 진단 시스템 구축이 가능하므로 영업소에서만 사용되던 차량 진단기를 개별 사용자가 사용할 수 있게 해준다. 또한 bluetooth의 Serial Port Profile을 기반으로 휴대전화기와 converting 보드간의 선을 제거함으로써 사용자가 간단하게 진단 어플리케이션이 탑재된 bluetooth handset에서 진단을 할 수 있다. 실험을 통하여 제안한 방식의 실제 환경에서 잘 동작함을 검증하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.43-44
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• 2015

LTE-Advanced system has been deployed with 2 and 4 transmission antennas (Tx) while the specification supports up to 8Tx. Due to deployment space, antenna dimension and complexity, the needs of deploying 8Tx system has not been motivated by operators. Recently, three dimensional (3D) beamforming with active antenna has attracted significant attention in the wireless industry. By incorporating 2D active array into LTE-A systems, the system offers freedom in controlling radiation on elevation and horizontal dimension. When the number of antennas increases in the form of 2D arrangement, spatial separation can be realized simultaneously in horizontal and elevation domain and vertical beam-steering can increase SINR of UEs in high floors. In this paper, we study the system operations and implementations for supporting 3D beamforming with 8Tx antennas. In our schemes, by reusing the conventional CSI feedback framework, the system can operate 2D active array without harming the backward compatibility. Evaluation results show that 3D beamforming provides capacity boosting over the conventional 2D beamforming systems while keeping same antenna structure.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2003.11a
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• pp.139-142
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• 2003

무선 네트워크에서 멀티미디어 전송을 위해 Delay를 줄이는 방법을 연구하고 이에 대한 실험적 검증을 하였다. 멀티미디어 데이터는 그 특성상 주어진 시간에 도착하지 못하는 데이터는 손실로 간주되므로 Loss에 못지 않게 Delay가 중요한 QoS 파라미터가 된다. 본 연구에서는 IEEE 802.11b를 그 환경으로 하여 멀티미디어 데이터를 트랜스코더를 이용하여 미디어 전환 후 전송 학 때 Delay를 최소화 할 수 있는 방안을 연구하였다. 무선 환경에서의 SNR을 기준으로 다양한 조건에서 패킷 사이즈와 전송 간격을 조절하여 무선 네트워크에서 Delay와 Loss가 적게 발생하는 환경을 찾아내었으며 이전 상태와 현재 상태를 비교하여 미래의 상태를 미리 예측학 수 있는 알고리즘을 개발하여 적용하였다. 이러한 연구 결과는 MPEG-4의 Video racket을 가장 효율적인 크기로 인코딩 할 수 있는 판단 근거를 만들게 해 주며, 예측 된 패킷 사이즈를 통하여 다음 전송이 이루어지기 전에 트랜스코더에게 미리 인코딩 하여 준비학 수 있도록 해서 네트워크에 적응적인 전송 방식으로 구현될 수 있는 장점이 있다.

• Journal of Broadcast Engineering
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• v.8 no.4
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• pp.392-398
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• 2003

In this paper, we propose the structure of multimedia file format based on MPEG-21 standard and the method to address a media resource within the file. The proposed multimedia file format supports the backward compatibility with MPEG-4 and the efficient addressing a media resource from a Digital Item that is XML-based MPEG-21 content. Also, the proposed multimedia file format can provide the functionality to package various types of media contents structurally and efficiently in digital broadcasting, Internet, and wireless environment. In addition, it can be a base model for multimedia file format that can be used for many different purposes such as integration and usage of metadata and multimedia contents.

• Journal of Broadcast Engineering
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• v.13 no.1
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• pp.119-127
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• 2008

Transmission of video over Internet or wireless network requires coded stream capable of adapting to dynamic network conditions instantly. To meet this requirement, various scalable video coding schemes have been developed, among which the Scalable Video Coding (SVC) extension of the H.264/AVC is the most recent one. In comparison with the scalable profiles of previous video coding standards, the SVC achieves significant improvement on coding efficiency performance. For adapting to dynamic network bandwidth, the SVC employs inter-layer switching between different temporal, spatial or/and fidelity layers, which is currently supported with instantaneous decoding refresh (IDR) access unit. However, for real-time adaptability, the SVC has to frequently employ the IDR picture, which dramatically decreases the coding efficiency. Therefore, an extension of SP picture from the AVC to the SVC for an efficient inter-layer switching is investigated and presented in this paper. Simulations regarding the adaptability to dynamic network bandwidth are implemented. Results of experiment show that the SP picture added SVC provides an average 1.2 dB PSNR enhancement over the current SVC while providing similar adaptive functionality.

• The KIPS Transactions:PartC
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• v.15C no.4
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• pp.263-272
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• 2008

Recently, WiBro has been developed to efficiently support real-time broadcasting with wireless system. MBS (Multicast Broadcast Service) based on WiBro has numerous applications such as DMB. Since the current MBS uses only common channel managed by scheduling, it cannot effectively support many users at the same time. This paper proposes a new counting scheme with which the channel mode can be properly switched between common channel and dedicated channel. It thus allows efficient use of limited radio resource in WiBro for the MBS.

• Journal of Broadcast Engineering
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• v.24 no.4
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• pp.613-622
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• 2019

A differential codebook design method using wireless channel's temporal correlation is proposed over closed loop multiple-input single-output (MISO) system. The single layer codewords in a codebook are selected among a set of phase elements. In the conventional codeword selection rule, codewords are assumed to be on a spherical cap and sine formula was used. In this paper, however, a new method using Pythagoras formula is employed to simplify computational complexity. Also, an adaptive differential codebook selection is adopted to enhance performance. Monte-Carlo simulations demonstrate that the proposed codebook is superior to the conventional ones.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.655-657
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• 2014

In this paper, a lego-type Ultra High Definition(UHD) media platform for cloud service have been proposed. The platform offers you a cloud service, which is freely able to share your UHD media in indoor and outdoor environment. Also, if various media products using the next-generation wireless communication(802.11ac and LTE Broadcast etc.) and proposed platform are utilized, everyone can develop easily because it is the lego-type. Therefore, the platform are expected to lead development of new market and invent industry since it can be applied to various businesses models.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.273-276
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• 2021

기존의 중계 시스템은 유선 기반으로 방송 중계차와 케이블 등이 필요하여 시간과 비용, 장소의 제약과 같은 여러 한계점을 가지고 있었다. 하지만 무선 중계 기술의 발전으로 무선 카메라만 있으면 긴급재난 현장이나 중계차가 들어갈 수 없는 지역에서도 중계가 가능하게 되면서 중계방송의 제한 범위가 좁아지고 있다. 따라서 본 논문에서는 시간과 장소의 제약 없이 방송을 송출할 수 있는 5G 무선 중계 시스템을 분석한다. 분석한 시스템은 5G 모뎀이 장착된 MNG 장비를 이용해 UHD와 4K 신호를 무선으로 처리하여 초저지연·초고화질로 송출한다. 또한 현존하는 멀티뷰 기술을 접목시켜 시청자들이 원하는 서비스를 제공한다.

• Journal of Intelligence and Information Systems
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• v.28 no.1
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• pp.45-68
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• 2022

The central and local governments of the Republic of Korea provided information necessary for disaster response through wireless emergency alerts (WEAs) in order to overcome the pandemic situation in which COVID-19 rapidly spreads. Among all channels for delivering disaster information, wireless emergency alert is the most efficient, and since it adopts the CBS(Cell Broadcast Service) method that broadcasts directly to the mobile phone, it has the advantage of being able to easily access disaster information through the mobile phone without the effort of searching. In this study, the characteristics of wireless emergency alerts sent to Seoul during the past year and one month (January 2020 to January 2021) were derived through various text mining methodologies, and various types of information contained in wireless emergency alerts were analyzed. In addition, it was confirmed through the population mobility by age in the districts of Seoul that what kind of influence it had on the movement behavior of people. After going through the process of classifying key words and information included in each character, text analysis was performed so that individual sent characters can be used as an analysis unit by applying a document cluster analysis technique based on the included words. The number of WEAs sent to the Seoul has grown dramatically since the spread of Covid-19. In January 2020, only 10 WEAs were sent to the Seoul, but the number of the WEAs increased 5 times in March, and 7.7 times over the previous months. Since the basic, regional local government were authorized to send wireless emergency alerts independently, the sending behavior of related to wireless emergency alerts are different for each local government. Although most of the basic local governments increased the transmission of WEAs as the number of confirmed cases of Covid-19 increases, the trend of the increase in WEAs according to the increase in the number of confirmed cases of Covid-19 was different by region. By using structured econometric model, the effect of disaster information included in wireless emergency alerts on population mobility was measured by dividing it into baseline effect and accumulating effect. Six types of disaster information, including date, order, online URL, symptom, location, normative guidance, were identified in WEAs and analyzed through econometric modelling. It was confirmed that the types of information that significantly change population mobility by age are different. Population mobility of people in their 60s and 70s decreased when wireless emergency alerts included information related to date and order. As date and order information is appeared in WEAs when they intend to give information about Covid-19 confirmed cases, these results show that the population mobility of higher ages decreased as they reacted to the messages reporting of confirmed cases of Covid-19. Online information (URL) decreased the population mobility of in their 20s, and information related to symptoms reduced the population mobility of people in their 30s. On the other hand, it was confirmed that normative words that including the meaning of encouraging compliance with quarantine policies did not cause significant changes in the population mobility of all ages. This means that only meaningful information which is useful for disaster response should be included in the wireless emergency alerts. Repeated sending of wireless emergency alerts reduces the magnitude of the impact of disaster information on population mobility. It proves indirectly that under the prolonged pandemic, people started to feel tired of getting repetitive WEAs with similar content and started to react less. In order to effectively use WEAs for quarantine and overcoming disaster situations, it is necessary to reduce the fatigue of the people who receive WEA by sending them only in necessary situations, and to raise awareness of WEAs.