• Journal of Broadcast Engineering
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• v.10 no.4 s.29
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• pp.587-598
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• 2005

KBS and ETRI have co-developed an advanced DOCR(Digital On Channel Repeater) which has an equalization and pre-distortion function and can be operated properly under lower isolation of reception and transmission antennas. Field tests of the DOCR were performed twice in Suwon area in 2004 and 2005. This paper summarizes the characteristics of the DOCR system and field test results in Suwon. The changes in DOCR coverage according to the different generations of ATSC DTV receivers were also analyzed. Basic concept to apply the DOCR system in DTV broadcasting networks in Korea is suggested through test results.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.253-257
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• 2004

디지털 TV 방송이 본격적으로 보급됨에 따라 2004 년 후반부터 각 방송사들은 디지털 방송네트워크의 설계를 위해 본격적인 전계강도 실측을 실시하고 있다. DTV 신호 측정에는, 가장 기준이 되는 전계강도 측정기를 비롯하여 DTV 복조기(demodulator), 각종 셋톱박스, 위성항법장치(GPS)를 이용한 지형정보시스템(GIS) 등 많은 장비가 필요하고 측정항목도 다양하여, 한 지역을 측정하는데 많은 시간이 소요될 뿐 아니라 측정자의 숙련도에 따라 측정결과의 정확도와 신뢰도가 떨어질 수 있다. 본 논문에서는 이러한 문제들을 해결하기 위해 다양한 계측장비와 운용장비의 제어를 체계적으로 관리하고 측정절차를 일반화하며 측정결과 데이터를 데이터베이스화하여 측정결과를 용이하게 파악할 수 있는 통합 측정 시스템을 제안한다. 또한, 본 시스템은 측정 뿐 아니라 지형정보시스템과 전계강도 예측시스템을 도입하여 측정지점 주변의 수신환경 분석 및 최적 수신위치의 검색정보 등을 제공하며, 다량의 측정결과에 대한 다양한 분석이 가능하여 커버리지 분석 및 송신 네트워크의 설계 등에 활용될 수 있다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.11a
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• pp.28-31
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• 2017

지상파 방송 3사(KBS/MBC/SBS) 수도권 본방송 파라미터와 동일하게 설정한 제주테크노파크 100W 실험국에서 ATSC 3.0 신호를 발사한 뒤, 제주시내 일대를 이동하면서 양시청 여부는 물론 실측값을 수집하였다. 결론적으로, 현재 전송파라미터 구성으로 송수신 정합에 이상 없이, 기술적인 관점에서 수도권 모바일HD 본방송이 가능함을 검증하였고, 커버리지 산출에 필수적인 물리계층 성능 지표인 ESR5에 대한 기준값, 즉 변조오류율(MER) 기준으로 11.3dB, 수신 신호 세기(Level) 기준으로 -85.0dBm 정도임을 도출하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.199-200
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• 2017

In order to meet the international performance requirements for eLoran testbed operation, it is necessary to measure ASF (Additional Secondary Factor) of vessel's route as well as differential correction and the provision using differential Loran (dLoran) station operation. According to HEA (Harbor Entrance and Approach) performance of the IMO, the position accuracy should be within 10meters. Therefore this paper presents the possibility to meet the position accuracy of the IMO HEA through simulation results.

• Journal of Broadcast Engineering
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• v.12 no.1 s.34
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• pp.11-27
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• 2007

T-DMB(Terrestrial-Digital Multimedia Broadcasting) for portable and mobile broadcasting service was officially launched in the metropolitan area of Korea in December 2005. The development of interactive data services and the expansion of T-DMB network have been now progressed, and the regional T-DMB broadcasters will be selected in the near future. Although it is important to evaluate service area and reduce a fringe area for optimizing RF coverage of T-DMB, there was no professional system to support those works, and therefore lots of resources in budget, manpower and time were required. The measurement considering characteristics of SFN(Single Frequency Network) is essential in the implementation of T-DMB network which needs to control synchronization, spacing and output power of transmitters. In addition, mobile measurement, enough measured parameters for many-sided analysis of reception quality, efficient management of enormous measured data and representation of measured results on the electronic map are also important in evaluating service area. In this paper, we derived requirements for a new measurement system in T-DMB by considering the above details, and we proposed and developed an integrated measurement and analysis system. The developed system was applied to the implementation of T-DMB network of KBS and field tests, and it proved its efficiency and accuracy in result.

• KIPS Transactions on Software and Data Engineering
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• v.5 no.12
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• pp.653-662
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• 2016

This paper describes a test case generation algorithm for Simulink/Stateflow models based on the Rapidly exploring Random Tree (RRT) algorithm that has been successfully applied to path finding. An important factor influencing the performance of the RRT algorithm is the metric used for calculating the distance between the nodes in the RRT space. Since a test case for a Simulink/Stateflow (SL/SF) model is an input sequence to check a specific condition (called a test target in this paper) at a specific status of the model, it is necessary to drive the model to the status before checking the condition. A status maps to a node of the RRT. It is usually necessary to check various conditions at a specific status. For example, when the specific status represents an SL/SF model state from which multiple transitions are made, we must check multiple conditions to measure the transition coverage. We propose a unique distance calculation metric, based on the observation that the test targets are gathered around some specific status such as an SL/SF state, named key nodes in this paper. The proposed metric increases the probability that an RRT is extended from key nodes by imposing penalties to non-key nodes. A test case generation algorithm utilizing the proposed metric is proposed. Three models of Electrical Control Units (ECUs) embedded in a commercial vehicle are used for the performance evaluation. The performances are evaluated in terms of penalties and compared with those of the algorithm using a typical RRT algorithm.

• Journal of Broadcast Engineering
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• v.9 no.4 s.25
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• pp.411-423
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• 2004

In Korea, Eureka-147 DAB (Digital Audio Broadcasting) temporarily decided as the standard system for digital audio broadcasting was evolved into DMB (Digital Multimedia Broadcasting) to complement the technical vulnerability in mobile reception of terrestrial DTV. According to introducing video service in T-DMB (Terrestrial DMB), 'Terrestrial DMB Experimental Broadcasting for Video Service', a national project of the MIC (Ministry of Information and Communication), was done for verifying the possibility of video service via T-DMB. The main objective of the project is computing the effective field strength and coverage for making a plan to build T-DMB broadcasting network and developing transmitting and receiving equipment. In case of digital broadcasting, it is absolutely essential to measure BER (Bit Error Rate) and electric field strength in order to evaluate coverage and quality of received signal. In this paper, we implement an integrated mobile measurement system for T-DMB. For this purpose, we propose efficient data structure and algorithm for BER measurement. By adding GPS (Global Positioning System) and electric field strength measurement parts into BER measurement part, we complete the integrated mobile measurement system, and then verify it by experiments and field tests. The developed system was used in a national project, 'Terrestrial DMB Experimental Broadcasting for Video Service' and measurement results will be used as fundamental data for building T-DMB broadcasting network.