• Journal of Broadcast Engineering
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• v.10 no.2
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• pp.166-173
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• 2005

In this paper, we propose a mobile channel estimation algorithm using matching pursuit algorithm for orthogonal frequency division multiplexing (OFDM) systems. Least square (LS) algorithm, which is used as a conventional channel estimation algorithm for OFDM systems, has error probability of channel estimation affected by effects of noise. By estimating the channel of sparse type, the proposed algorithm reduces effects of noise during time intervals that multi-path signal doesn't exist. The proposed algorithm estimates a mobile receivingchannel using pilot information transmitted consequently. We compare performance of the proposed algorithm with the LS algorithm by measuring symbol error rate with 64QAM under a mobile multi-path fading channel model.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.229-232
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• 2005

현재 디지털방송 서비스가 확대되고 있는 시점에서 방송콘텐츠 보호에 대한 중요성이 날로 부각되고 있다. 이에 MPEG-2 IPMP는 디지털방송 서비스를 제공받아 소비하는 방송 단말로부터 방송콘텐츠를 불법적으로 사용할 수 없도록 보호할 수 있게 정의하고 있는 대표적인 국제 표준 규격이다. IPMP 규격을 기반으로 한 방송 단말을 구현함에 있어 보호된 방송콘텐츠를 IPMP 툴로 처리하여 소비하게 되는데 만약 방송 단말에 IPMP 툴이 없다면 방송되고 있는 MPEG-2 전송스트림이나 원격지에서 필요한 IPMP 툴을 다운로드 받아 방송 단말에 업데이트를 시켜야 한다. 이때 방송 단말에서 위와 같은 기능이 구현되기 위해서는 구체적인 소프트웨어 설계 방식을 통해 다양한 플랫폼에 대해 구현된 기능에 대한 재사용성이나 호환성을 확보하는 것이 효율적이다. 하지만 점차적으로 복잡해지고 다양해지는 멀티미디어 기기들의 기능들을 위해 탑재되는 소프트웨어 역시 복잡해지고 있어 그 재사용성이나 호환성이 떨어지고 있는 실정이다. 본 논문에서는 이러한 소프트웨어의 재사용성이나 호환성을 최대한 보장할 수 있도록 현재 MPEG(ISO/IEC JTC1/SC29/WG11)에서 표준화가 진행 중인 MPEG Multimedia Middleware(M3W) 규격을 기반으로 한 소프트웨어 설계 방식을 살펴보고, 디지털방송 단말에서 IPMP 툴 업데이트 기능이 효율적으로 설계되고 구현될 수 있는 소프트웨어 구조를 제안하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.73-76
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• 2005

한국방송(KBS)은 전자통신연구원(ETRI)과 공동으로 송수신 안테나의 낮은 분리도(isolation)하에서도 운용이 용이하며 중계기 내부의 왜곡을 보상할 수 있는 DOCR(Digital On-Channel Repeater)을 개발하였다. 개발된 DOCR의 성능과 서비스 커버리지를 측정하기 위하여 수원 지역에서 2004년과 2005년 두 차례의 필드테스트를 공동으로 실시하였다. 본 논문에서는 개발된 DOCR시스템에 대하여 그 특징을 설명하고 수원 지역에서 실시된 필드테스트 결과를 분석한다. 또한, 다양한 세대의 ATSC 수신기를 측정에 사용함으로써 수신기 성능에 따른 DOCR 서비스 커버리지의 변화를 측정하였다. 측정결과에는 DOCR의 사용에 따른 수신성공률, 수신마진, 수신용이성(수신가능각도)등이 포함되며 측정 지역의 수 년간의 테스트 결과를 종합하여 서비스 범위내의 수신성능을 분석한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.239-244
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• 2006

최근 인터넷에서 많은 관심을 보이고 있는 개인 미디어(UCC;User Created, Contents, VC2;Viewer Created Contents, 이하 UCC-사용자가 직접 제작한 미디어 콘텐츠를 불특정 다수에게 제공하는 서비스) 중에 비디오/오디오 콘텐츠를 영상 콘텐츠의 기본적인 매체라 할 수 있는 TV상에서 직접 즐길 수 있다면 미디어의 대상과 그 미디어의 Entertainment적인 효과는 배가될 것이다. 디지털 케이블 방송에서 UCC와 같은 다양하고 많은 미디어 콘텐츠를 디지털 TV상에서 서비스를 하고자 한다면 현재의 OCAP(OpenCable Application Plat form)기반에서는 RVOD(Real Video on Demand)와 동일한 서비스 모델을 가져야 하는 부담과 UCC 제공을 위한 방송 플랫폼별 인터페이스가 필요할 것이다. 이러한 문제점을 Return Path를 통한 RTP(Real-time Transport Protocol;RFC1889)을 이용해서 기존의 VoD(Video on Demand)스트림의 대역에서 분리하고 별도의 VOD프로토콜을 구현함으로써 라이브 방송환경과 동일한 인프라의 지속적인 확장보다는 일반적인 네트워크 프로토콜을 이용하여 VoD서비스를 위한 인프라에 많은 영향을 받지 않는 서비스가 가능할 수 있을 것이다. 따라서 본 논문에서는 RTP를 위한 Set-Top-Box상의 다운로드 가능한 구조의 클래스 분석과 클라이언트 대응의 UCC Transcoding 및 전송을 위한 스트리밍 서버의 설계에 중점을 두고 경량화 된 VOD서비스 및 시스템을 설계함으로써 방송환경 하에 On-Demand서비스의 효율적인 확장성과 보다 많은 콘텐츠 등록 및 활용의 기회를 가져올 수 있을 것으로 기대한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.4
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• pp.284-290
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• 2014

To successfully explore the moon by lunar lander, it is essential to guarantee the safe landing of lunar lander. Therefore, efficient shock absorption system of lunar lander should be designed in order to reduce landing impact force. Also, for more practical design of lunar lander, it is important to consider the effect of lunar regolith. In the line of thought, finite element model of lunar lander considering the effect of lunar regolith is developed. To reduce landing impact force, optimization of shock absorption system for lunar lander has been carried out. In optimization, sequential approximate optimization method based on meta-model is used. Through the result of optimization, it is verified that landing impact force on lunar lander can be efficiently reduced by the present optimization procedure.

• Journal of Broadcast Engineering
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• v.21 no.2
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• pp.180-191
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• 2016

When up-scaling algorithms for visible light images are applied to infrared (IR) images, they rarely work because IR images are usually blurred. In order to solve such a problem, this paper proposes an up-scaling algorithm for IR images. We employ adaptive dynamic range encoding (ADRC) as a simple classifier based on the observation that IR images have weak details. Also, since human visual systems are more sensitive to edges, our algorithm focuses on edges. Then, we add pre-processing in learning phase. As a result, we can improve visibility of IR images without increasing computational cost. Comparing with Anchored neighborhood regression (A+), the proposed algorithm provides better results. In terms of just noticeable blur, the proposed algorithm shows higher values by 0.0201 than the A+, respectively.

• Journal of Broadcast Engineering
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• v.18 no.5
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• pp.722-729
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• 2013

For low contrast images, a histogram equalization is possible to easily identify information when the intensity is concentrated in an image. Over contrast enhancement is the problem of generating an unnatural image cognitively because the focus of existing techniques was the contrast enhancement. In order to solve this problem, CLAHE method solves unnatural problems by limiting contrast using a maximum threshold. However, this method has an extra problem that concealed detail information in an image. This paper proposes a detail-map based on the multiple layers block overlapped histogram equalization in order to avoid loss of detail information. Loss of detail information has been made to minimize as combining images with limited contrast enhancement using a detail-map in each layers.

• Journal of Elementary Mathematics Education in Korea
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• v.14 no.3
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• pp.659-680
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• 2010

Under the banner "Toward Global Excellence in Teacher Education", Daegu National University of Education has strived for the single aim of excellence in pre-service and in-service for over fifty years. Specially the department of Mathematics education aims to develope students' mathematical power which is related to elementary school mathematical concepts & theories. However not a few of the students seem to have test-anxiety which is relate to teacher recruitment examination. In these view, we conclude that students must have been suffered from test anxiety. Consequently the results of the study are follow. $\cdot$ 2nd paper-pencil test of the elementary school teacher recruitment(2010) has been emphasized on statement of examinee logocal thought about all 10 subjects. $\cdot$ 3rd test of the elementary school teacher recruitment(2010) has been focused on only speaking english of examinee. Thus we conclude that these Recruitment Examination(2010) couldn't minimize the test anxiety of the students. Therefore next test of the elementary school Teacher Recruitment should contain on mathematical problem-solving in elementary school mathematics textbooks.

• Journal of Elementary Mathematics Education in Korea
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• v.23 no.3
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• pp.289-303
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• 2019

The aim of this study was to seek for the purpose of social justice of mathematics education based on the understating of a critical race perspectives. This paper is consisted of two parts. First, I analyzed literatures of mathematics education for social justice in order to understand the discussions and concerns related to the topic. Second, I used the selected tenets of critical race theory to examine mathematics education for social justice scholarship. From the analysis, I concluded the current capacity of mathematics education for social justice toward addressing race issues in a mathematics classroom.

• Journal of Science Education
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• v.34 no.1
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• pp.164-174
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• 2010

The purpose of this study was to find out taxonomic characteristics of objectives infered from questions of summative evaluation by analyzing those objectives with Bloom's revised taxonomy of educational objectives. 1,711 questions of midterm and final examinations collected from 25 middle schools were analyzed to classify objective of each question. The major findings of the study were as follows: first, from the analysis of objectives in the knowledge dimension, the assessment of factual knowledge was most prevailing(67.6%) in the biology summative evaluation. In the cognitive process dimension, memory assessment was most dominant(76.1%). Thus, the main objectives of evaluation leaned toward particular classes in the Bloom's revised taxonomy, which was different from the findings of earlier studies on the weights of evaluation areas. Second, the level of the objectives should be determined in consideration of the grade of middle schoolers, as their cognitive level improves with grade. In fact, however, there was no difference among three grades in characteristics of objective taxonomy.