• Journal of the Korean Vacuum Society
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• v.20 no.1
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• pp.30-34
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• 2011

We investigated the structural, electrical and optical characteristics of thin films with ITO deposited by a low temperature RF reactive magnetron sputtering. The deposited thin films were annealed for 2 hours at various temperatures of $50^{\circ}C$, $100^{\circ}C$, $150^{\circ}C$, $200^{\circ}C$ and $250^{\circ}C$ and were analyzed by using X-ray diffractometer, scanning electron microscopy and 4 point probe. The films annealed at temperatures higher than $150^{\circ}C$ were found to be crystallized and their electrical resistance were decreased from $40{\Omega}cm$to $18{\Omega}cm$. The optical transmittance of the film annealed at $150^{\circ}C$ was increased by over 87% in the 450 nm ~ 900 nm wavelength range. Our results indicate that the films with ITO deposited at even a low temperature can show better optical and electrical properties through a proper heat treatment.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.89-92
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• 2004

방송과 통신의 융합, 방송서비스의 다양화와 더불어 방송의 디지털화는 기존의 아날로그 방식에 비해 고화질 및 고음질의 방송 서비스 제공 및 타 매체와의 호환성 그리고 다양한 부가 서비스의 제공 등에 있어서 많은 이전을 제공할 수 있다. 또한, 디지털방송 방식은 기존 아날로그 방식의 이동수신 문제점을 해결하고자 디지털 오디오 방송(DAB: Digital Audio Broadcasting)에 멀티미디어 서비스를 .제공하는 디지털 멀티미디어 방송(DMB: Digital Multimedia Broadcasting)을 제안하였다. 지상파 DMB 방송은 유럽의 Eureka-147 방식의 DAB를 기반으로 하며 디지털 라디오방송과 함께 오디오 외에도 다양한 멀티미디어를 전송하고, 콘텐츠에 대화형 기능을 포함하는 서비스 형태를 목표로 하고 있다. 현재 지상파 DMB 서비스에서는 기본적인 AV 서비스를 위해 비디오는 AVC, 오디오는 BSAC에 대해 규정하고 있다. 또한 AV 규격 외에 대화형 서비스를 제공하기 위한 보조 데이터로서 장면기술 데이터와 그래픽 데이터를 지원하고 있다. 따라서 본 논문에서는 지상파 DMB를 이용한 대화형 서비스를 제공하기 위해 요구되는 초기 객체 정보, 객체 정보, 장면 구성 정보를 바이너리 형태로 생성해 주는 MPEG-4 바이너리 컨버터를 설계하고 구현하였다.

• Journal of Broadcast Engineering
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• v.8 no.4
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• pp.465-472
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• 2003

In this paper we propose the structure of MPEG-4 multimedia player platform for Terrestrial Digital Multimedia Broadcasting (DMB) Service. Korea will launch DMB service at next 2004 you based on Eureka-147 Digital Audio Broadcasting (DAB) Service System. This new mobile multimedia broadcasting services provide not only high quality digital audio broadcasting services, but also various multimedia data broadcasting services including high quality video. For the sake of MPEG-4 Systems technologies, it will provide an interactive service to users in the near future. Therefore it terminal shall have various functionalities as well as playing audio-visual contents. However there is no precedence standard for such mobile interactive multimedia broadcasting system. Therefore it is very import to provide the multimedia player platform of DMB service for accelerating the development process of commercial terminal and providing a direction of next DMB terminal structure.

• Journal of Broadcast Engineering
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• v.8 no.3
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• pp.250-258
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• 2003

Recently, the transition from conventional analog broadcasting to digital broadcasting has been proceeding as a result of the advance in digital multimedia broadcasting technique. In radio broadcasting, Eureka-147 DAB(Digital Audio Broadcasting) was decided as the standard system of digital radio broadcasting in Korea. In addition to CD quality audio, a variety of data services and excellent performance in mobile reception can be served by DAB, and DAB was evolved into DMB(Digital Multimedia Broadcasting) in Korea for the purpose of emphasizing moving picture multimedia service by DAB. In case of digital broadcasting, it is absolutely essential to measure the BER(Bit Error Rate) in the received signal in order to evaluate the coverage obtained by a transmitter and the quality of the received signal. In this paper, we propose efficient subchannel data structure and BER measurement algorithm. and then verify it by laboratory experiments. With a proposed method, the synchronization for BER measurement is easily obtained and especially the exact results can be obtained by classifying the lost bits which are included in the reception-failed CIFs(Common Interleaved Frame) into errors. This makes the proposed BER measurement system especially appropriate to DMB in which the frequent changes in channel status caused by mobile reception environment exist.

• The Journal of the Korea Contents Association
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• v.17 no.6
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• pp.39-54
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• 2017

This study started from the consciousness that the community media practice studies have been confined to the traditional terrestrial broadcasting. The following research results and implications were obtained by analyzing Daedeok-valley Radio's case to elucidate characteristics of online-based community media and content production and distribution characteristics neglected in previous researches. First, online community media activities are civic/citizen media activities that capture the value of local communities, and this locality is realized through media content production and its online distribution. Second, contents of online community media link members of the community, and individuals become nodes, interacting both online and offline. Therefore, online-based citizen media activities can be utilized effectively as a means to enhance civic participation and to achieve the locality of community in online and offline spaces depending on strategies for online contents production and distribution. Utilizing online infrastructures for media content creation and distribution in Korea demonstrates potential opportunities of local online media to be considered as niche media that can increase its own sustainability.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.185.1-185.1
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• 2015

본 연구에서는 라디오파 마그네트론 스퍼터링 방법을 사용하여 증착 온도를 변화시켜면서 Eu 이온이 도핑된 MgMoO4 적색 형광체 박막을 사파이어 기판 상부에 성장하였다. 타겟은 고상반응법을 사용하여 직접 제작하였다. 형광체 박막의 구조, 표면, 광학적 특성은 X-선 회절장치, 주사전자현미경, 투과도 및 광여기발광 측정장치를 사용하여 측정하였다, 증착 온도는 100, 200, 300, $400^{\circ}C$이었으며, 증착 후 $870^{\circ}C$에서 열처리 공정을 실행하였다. 이와 더불어, $400^{\circ}C$에서 증착한 박막을 다양한 온도 $770-920^{\circ}C$에서 열처리를 수행하여 각각의 특성을 분석하였다. 증착 온도 $200^{\circ}C$에서 성장한 박막의 경우에 614 nm에 피크를 갖는 주 적색 발광 피크가 관측되었으며, 열처리 온도를 달리한 박막의 경우에는 $920^{\circ}C$에서 가장 강한 발광 피크가 나타났다. UV-VIS 분광광도계를 사용하여 박막의 투과도와 흡광도를 측정하였으며, Tauc의 모델을 사용하여 밴드갭 에너지를 계산하였다. 증착 온도 변화에 따라 성장된 박막의 투과도는 평균 82% 이상 이었으며 밴드갭 에너지는 4.1 eV이었다. 박막의 결정 구조는 단사정계임을 확인하였다. 특히, 결정 입자, 발광 피크의 세기와 투과도의 상관 관계를 조사하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.184.2-184.2
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• 2015

최근에 적색 발광체를 개발하고자 무기물 모체에 다양한 활성제 이온을 주입하는 연구가 상당한 관심을 끌고 있다. 본 연구에서는 발광 효율이 높은 적색 형광체 박막을 제조하고자 활성제 이온 $Eu^{3+}$가 도핑된 $CaMoO_4:Eu^{3+}$를 라디오파 마그네트론 스퍼터링을 사용하여 증착하였다. 두 종류의 박막을 성장하였는데, 한 종류는 증착 온도 ($100-400^{\circ}C$)를 달리하여 성장한 후 $570^{\circ}C$에서 열처리를 실시하였고, 다른 한 종류는 동일한 온도 $300^{\circ}C$에서 증착한 후에 열처리 온도(420, 470, 520, $570^{\circ}C$)를 변화시켜 제조하였다. 증착 온도와 열처리 온도에 따른 적색 형광체 박막의 흡광과 발광 특성, 결정 구조, 입자의 크기와 표면 형상, 밴드갭 에너지의 크기를 조사하였다. 열처리 온도에 따른 적색 형광체 박막의 경우에, 파장 308 nm로 여기 시켰을 때 발광 세기가 가장 강한 616 nm의 주 피크를 방출하는 적색 스펙트럼이 나타났으며, 열처리 온도가 증가함에 따라 적색 발광 스펙트럼의 세기는 증가하는 경향을 보였다. 증착 온도 변화에 따른 형광체 박막의 경우에, 272 nm로 여기 시켰을 때 614 nm의 적색 발광 피크를 확인 할 수 있었다. 모든 박막의 결정 구조는 정방정계이었다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.1
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• pp.66-71
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• 2004

Airborne contaminant particles are intruded into optical disk drive(ODD) due to the flow caused by disk rotation and can be adhered to objective lens, which causes read/write errors. Such a phenomenon can be a serious problem for high-density storage devices. The purpose of this paper is to understand the effect of particle contamination of objective lens in a CD-ROM drive on laser diode power and photo diode RF signal. The measurements of laser power and readout RF signal were carried out by using a laser power meter and a time interval analyzer, respectively. The parameters for estimating a readout-signal' distortion were its jitter and amplitude. Alumina(Al$_2$O$_3$) particles were used as test dust particles. The results show that the failure for data access happened as the degree of lens contamination was greater than 20％.

• Journal of the Korean institute of surface engineering
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• v.41 no.4
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• pp.129-133
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• 2008

Nitrogen and aluminum codoped ZnO(NAZO) thin films were grown on glass substrates with changing the nitrogen flow ratio by radio-frequency magnetron sputtering. The structural, optical, and electrical properties of the NAZO films were investigated. The surface morphologies and the structural properties of the thin films were analyzed by using the X-ray diffraction and scanning electron microscopy. The NAZO thin film, deposited at nitrogen flow ratio of 0%, showed a strongly c-axis preferred orientation and the lowest resistivity of $3.2{\times}10^{-3}{\Omega}cm$. The intensity of ZnO(002) diffraction peak was decreased gradually with increasing the nitrogen flow ratio. The optical properties of the films were measured by UV-VIS spectrophotometer and the optical transmittances for all the samples were found to be an average 90% in the visible range. Based on the transmittance value, the optical bandgap energy for the NAZO thin film deposited at nitrogen flow ratio of 0% was determined to be 3.46 eV. As for the electrical properties, the carrier concentration and the hall mobility were decreased, but the electrical resistivity was increased as the nitrogen flow ratio was increased.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.343-350
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• 2003

Circularly polarized-dual band antenna for GPS(Global Positioning System) and satellite radio system is developed and measured. Both circular polarization and overall antenna dimension reduction are achieved by placing a partially filled high-permittivity substrate under radiating edges. The bandwidth is also improved by choosing an optimal geometric configuration with a partially filled high permittivity substrate. The proposed antenna can be installed on moving vehicles or ships.