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5G 이동통신 기반 재난 방송의 수신 성능 향상을 위한 부가 서비스 기법
장석진(Sekchin Chang) 한국방송·미디어공학회 2021 방송공학회논문지 Vol.26 No.2
The emergency alert broadcast service based on cellular communications is defined as CBS. However, the CBS just supports a limited text message, which might be unavailable to foreigners, who are unfamiliar with local characters. The CBS protocol relies on a broadcast mechanism. Such a broadcast technology exhibits that the number of outage users significantly increases under poor channel conditions. In this paper, we present a supplementary service technology for 5G CBS, which considerably enhances the accessibility of foreigners and illiterate persons, and the receiver performance. For the enhanced receiver performance, the proposed supplementary service approach effectively exploits the device-based geo-targeting capability that the 5G CBS can afford to offer.
이동통신 기반의 재난경보 방송을 위한 동기식 협력통신 방식
장석진(Sekchin Chang) 한국방송·미디어공학회 2014 방송공학회논문지 Vol.19 No.2
The CBS methodology has been utilized in order to make a rapid broadcast of emergency alert based on cellular systems. We present a synchronous cooperative communication method for the CBS. Especially, we suggest a synchronization scheme and a data recovery approach for high-rate cooperative communications. For the high-rate transfer of emergency alert, the cyclic prefix is added to the preamble for the synchronization. For the data recovery, the Alamouti technique is utilized on frequency domain, which is similar to SC-FDE. The simulation results confirm that our proposed scheme is very suitable for the CBS.
장석진(Chang, Sekchin),최성종(Choi, Sung Jong) 한국방송·미디어공학회 2011 한국방송공학회 학술발표대회 논문집 Vol.2011 No.7
최근 IT 기술의 발전으로 TV, DMB, 이동통신망 등을 이용한 효율적인 재난문자방송 서비스가 국내외에서 관심을 받고 있다. 특히. 이동통신망은 지역단위 전송이 가능하기 때문에 지진, 해일 등의 심각한 재난이 예상되는 지역에 신속한 경보 서비스를 가능하게 해준다. 국내에서는 이미 2G 이동통신망을 이용하여 대국민 재난문자방송 서비스를 실시하였다. 그러나 국내외적으로 3G/4G 이동통신망 서비스가 본격화 되었으며, 이에 맞는 재난문자방송 서비스가 필요한 실정이다. 이에 본 논문에서는 이동통신망을 이용한 재난문자방송 서비스인 CBS의 국내외 동향과 표준안 등을 소개하며, 국내 CBS의 향후 나아갈 방향을 제시하고자 한다.
5G 이동통신 용 재난경보 방송의 메시지 구조를 이용한 이미지 정보 및 URL 표출기법
장석진(Sekchin Chang) 한국방송·미디어공학회 2021 방송공학회논문지 Vol.26 No.5
Current cellular systems rely on a CBS protocol for emergency alert broadcast services. However, the CBS protocol just specifies the delivery of a limited text message. Therefore, foreigners, who are unfamiliar with local characters, may have some difficulties in understanding the received CBS text message. The CBS protocol also reveals a distinct restriction in delivering abundant information because of a limited number of text characters. In order to overcome the weak points of the current CBS protocol, we propose a display method of image information and URL on the screens of mobile terminals for the received CBS text message in this paper. The presented approach effectively utilizes the message structure of CBS for 5G cellular systems.
RF433 무선 센서 네트워크와 ARDUINO-YUN 기반의 게이트웨이를 활용한 전력관리 IoT 시스템
최은석,심재용,장석진,Choi, Eun-Seok,Shim, Jae-Ryong,Chang, Sekchin 한국정보통신학회 2017 한국정보통신학회논문지 Vol.21 No.5
현재 산업 분야 전반에 걸쳐 다양한 IoT 기술들이 연구되고 있으며 이 기술들을 효과적으로 적용하는 중이다. 그러나 IoT 대부분의 연구들은 센서 디바이스, 게이트웨이, 네트워크 서버, 그리고 어플리케이션 서버로 연결되는 복잡한 구조에 의존한다. 물론 유연성과 확장성 측면에서 이들은 분명한 장점이 있다. 문제는 이와 같은 복잡한 구성은 구현상의 어려움과 추가적인 비용을 초래하기 때문에 소규모 네트워크 환경의 산업 분야에서 IoT 도입을 저해하는 결과로 나타나고 있다. 따라서, 본 논문에서는 소규모/저비용의 IoT 환경이 필요한 산업분야에 적용 가능한 시스템 구조를 제안 한다. 또한 RF433 기반의 무선 센서 네트워크, 아두이노 윤 기반의 게이트웨이, APM (Apache, PHP, MySQL)을 적용한 어플리케이션 서버를 구현하고 이들 간의 효율적인 전력관리 방안을 제시한다. These days, research has been made for a variety of internet of things (IoT) technologies over industrial fields. The current research trend includes the effective adoption of the IoT technologies. But, most IoT researches assume a relatively complicated structure, which consists of sensor devices, gateway, network server, and application server. Of course, the structure has distinct merits in the aspects of flexibility and expandability. However, the complicated structure causes the system implementation overhead including high-cost implementation, and hinders the practical usage of IoT in the industry areas, which require a small-size network. In this paper, we propose a novel IoT system architecture, which guarantees the small-size network and the low-cost implementation. Also, we implement the infrastructure, which includes the RF433-based sensor network, the ARDUINO-YUN based gateway, and the application server using Apache/PHP/MySQL (APM) package. Finally, we present the effective power management scheme among these components.
무선 OFDM 시스템에서 다이버시티를 이용한 효율적인 주파수 옵셋 추정
김준영(Joon Young Kim),장석진(Sekchin Chang) 대한전기학회 2006 정보 및 제어 심포지엄 논문집 Vol.2006 No.1
This paper presents an efficient frequency offset (FO) estimation algorithm for the orthogonal frequency division multiplexing (OFDM) based wireless local area networks (WLANs). The packet preamble imformation is utilized on the high rate WLAN standards adopted by the IEEE 802.11a. We present FO estimation schemes using diversity. In the simulation results, we prove that the presented schemes can improve the estimation performance compared with the convolutional scheme.
이동통신 기반의 재난경보 방송 재전송을 위한 무선인지 기법
송미화(Mihwa Song),장석진(Sekchin Chang) 한국방송·미디어공학회 2014 방송공학회논문지 Vol.19 No.3
The CBS methodology has been standardized in order to make a rapid broadcast of emergency alert message for cellular users. However, the standard does not specify a retransmission request mechanism in the case that the users fail in receiving the alert message. Therefore, we propose a retransmission request scheme based on cognitive radio for the CBS technology in this letter. The simulation results confirm that our proposed scheme is very suitable for the retransmission method in CBS-based emergency alert broadcast systems.
송미화(Mihwa Song),장석진(Sekchin Chang),이용태(Yongtae Lee) 한국방송·미디어공학회 2015 방송공학회논문지 Vol.20 No.3
The CBS functionality is defined for emergency alert service in cellular systems. Previously, a cooperative communication technique was proposed for more reliable CBS functionality. However, the relays for cooperative communications may fail in receiving emergency message, which may cause a critical latency. Therefore, we propose a novel cooperative communication technology in this letter, which incudes additional T-DMB functionality in relays. Analytical and empirical evaluations confirm that the proposed method is very suitable for rapid emergency alert broadcast.