• Journal of the Korean Vacuum Society
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• v.19 no.4
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• pp.287-292
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• 2010

We have investigated the effects of oxygen flow ratios on the structural, morphological, and optical properties of AlN thin films grown by using radio-frequency reactive magnetron sputtering. The AlN thin films were deposited at $300^{\circ}C$ of substrate temperature, and the reactive gas were supplied with both nitrogen and oxygen. The oxygen flow ratio was varied by controlling the amount of oxygen with respect to the total mixed gases, 0%, 10%, 15%, 20%, 25%, and 30%. The structural, morphological, and optical properties of the deposited AlN thin films were examined by using X-ray diffractometer, scanning electron microscopy, and ultraviolet-visible spectrophotometer. The AlN thin film grown at 10% of oxygen flow ratio indicated an average transmittance of 91.3% in the wavelength range of 350~1,100 nm and an optical band gap of 4.30 eV. The experimental results suggest that AlN thin films can be deposited optionally by varying the oxygen flow ratio.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.95-103
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• 2015

The Korea terrestrial broadcasting has TV and Radio, DMB. The TV broadcasting was converted from the analogue method to the digital method at the end of 2012. However the radio broadcasting is still in analogue method. The introduction of digital radio technology will bring many benefits such as high-quality of sound, various additional services and increase of efficiency in frequency utilization. In many countries, the radio broadcasting is been servicing in digital method. The discussion was begun on this year for the introduction of digital radio technology in Korea. So, to prepare against introduction of DAB system among digital radio technology, this paper proposes channel allocation method for each local radio broadcasting and the composition of national SFN, and proves the proposed method through the interference analysis.

• Information and Communications Magazine
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• v.25 no.6
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• pp.48-51
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• 2008

우리나라는 Eureka-147 방식의 디지털 라디오를 이동 멀티미디어로 확장하기로 하고 지상파 DMB로 불리는 비디오규격을 개발하였다. 지상파 DMB의 국제표준화를 위해 우리나라가 2004년 3월에 시스템 개요와 필드 테스트 결과를 ITU-R에 기고함에 따라 ITU-R 내에서 본격적인 이동 멀티미디어 표준화 논의가 시작되었고 우리나라 지상파 DMB 외에 일본의 ISDB-T, 노키아의 DVB-H와 퀄컴의 FLO 등을 대상으로 이동 멀티미디어 시스템 표준으로 개발하게 되었다. 3년여에 걸쳐 각 국간의 첨예한 이해관계에 의한 의견충돌과 합의를 거쳐 표준안이 작성되었으며, 표준화 방식은 휴대수신용으로 한정하고 각 시스템들을 알파벳에 따른 멀티미디어 시스템으로 명명하였다. 우리나라 지상파 DMB는 유럽 진출을 염두에 두고 디지털 음성방식 A인 Eureka-147 과의 호환성을 강조하기 위해 멀티미디어 시스템 A로 이름을 붙이기로 하였다. 지난 4월에 열린 ITU-R SG 6 회의에서 이동 멀티미디어의 표준화를 최종적으로 결정되었고 이후 회원국의 동의회신 절차를 거쳐 2007년 12월에 지상파 DMB가 ITU에서 휴대이동방송 시스템 중 하나로서 승인되었다.

• Trans-
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• v.1
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• pp.117-139
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• 2016

Radio, the first broadcasting medium in history, is also the first mobile medium that meets the currently mobile ecology based on mobile communications network. As a result, it is easily approachable to consumers, can easily engage individual consumers, and its program contents have a huge appealing power to individual listeners, allowing it to form intimacy with audiences at the closest distance. However, the listening rating of radio has decreased greatly because it has experienced various changes by many other competitive media such as TV and internet and it has been influenced by relative constant hypothesis. Also, radio now faces a bigger competition due to the emergence of smartphone. In this circumstance, radio showed movements to evolve into a digital radio that presents improved sound, strengthened reception power, and increased number of channels, but it suddenly changed to DMB and portable multimedia DMB is having huge problems in its marketability due to smartphone. Yet, the listening rating of analogue radio broadcasting that remained unchanged was 13.99% in 2014, an increase by 47% from 2011, and the percentage of listeners under the age of 18 increased by 2.4 times from 2011 to 2014, which was a unique and interesting phenomenon. Accordingly, this paper compared the characteristics of internet and radio that have the traits of daily life, information, individuality, participatory, adventurousness, alternative media, expertise, and sound media. The paper then examined the listening method of radio, in which the direct groundwave antenna reception through a vehicular device is the most common form during the use of transportation means. Finally, it sought to investigate the future of radio based on the understanding of the increase in radio listening ratings, especially by comparing it to the characteristics of smart generation that focus on smartphone and the internet The study results demonstrated that entertainment and amusements are attempting at changes while they used to be obtained selectively by the smart generation from fragmentary information. In addition, radio is expected to become an influential medium in the future through its advantages of 'selected information' and reliability. However, considering such possibilities, radio needs to build the expertise and reliability of broadcasting contents much more at the same time as its digitalization, and it will be able to have its own competitiveness by focusing on various experiences and cultural exposures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5007-5014
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• 2010

Recently n Korea, the House of Commons and terrestrial broadcasting facilities integrated with FM radio and the satellite compulsory was amended to transfer MATV(Master Antenna Television) adjusted by SMATV(Satellite Master Antenna Television). While the SMATV was accepted by default in most other countries, our county did not accept it as the default for broadcast. Because domestic cable and satellite television service providers are conflicts with their interest. bAs a result, the hybrid amplifier for SMATV technology development and volume production for the state is insufficient. Therefore, terrestrial television broadcast bands (54 ~ 806Mhz) and FM radio broadcast band (88 ~ 108Mhz) band satellite with (950 ~ 2150Mhz) to amplify the development of a broadband amplifier with subsequent resolution of problems is also presented in this study.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.4
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• pp.51-62
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• 2012

According to the Lighthill and Whitham's shock wave model, a shock wave exists even in a homogeneous speed condition. They referred this wave as unobservable- analogous to a radio wave that cannot be seen. Recent research has attempted to identify how such a counterintuitive conclusion results from the Lighthill and Whitham's shock wave model, and derive a new asymptotical shock wave model. The asymptotical model showed that the shock wave in a homogenous speed traffic stream is identical to the ambient vehicle speed. Thus, no radio wave-like shock wave exists. However, performance tests of the asymptotical model using numerical values have not yet been performed. We investigated the new asymptotical model by examining the implications of the new model, and tested it using numerical values based on a test scenario. Our investigation showed that the only difference between both models is in the third term of the equations, and that this difference has a crucial role in the model output. Incorporation of model parameter${\alpha}$ is another distinctive feature of the asymptotical model. This parameter makes the asymptotical model more flexible. In addition, due to various choices of ${\alpha}$ values, model calibration to accommodate various traffic flow situations is achievable. In Lighthill and Whitham's model, this is not possible. Our numerical test results showed that the new model yields significantly different outputs: the predicted shock wave speeds of the asymptotical model tend to lean toward the downstream direction in most cases compared to the shock wave speeds of Lighthill and Whitham's model for the same test environment. Statistical tests of significance also indicate that the outputs of the new model are significantly different than the corresponding outputs of Lighthill and Whitham's model.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1429-1434
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• 2003

A number of dust particles are intruded into ODD(Optical disk drive) due to the flow caused by disk rotation and are adhered to a lens or disk surface. The space between the disk and the lens is being reduced. Someone indicates the problems of this drive that are relatively small data storing capacity and slow access time. In recent, the problems of this optical disk drive mentioned above are being solved by adding the speed of the disk's revolution, making the actuator high-speed or light, and making the beam spot size smaller than making the space narrow between disk and lens. These particle contamination affects seriously RF Signal, readout signal in an ODD. Especially, the affected parts by a particle contamination in an ODD's readout signal are objective lens and media.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.160-160
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• 2012

라디오파 마그네트론 스퍼터링 방법을 사용하여 유리 기판 위에 Eu 이온이 도핑된 $BaWO_4$ 박막을 성장 시킨 후에 온도 범위 $400{\sim}550^{\circ}C$에서 급속 열처리를 수행하였다. 박막의 결정 구조와 표면 형상은 각각 x-선 회절법과 주사전사현미경으로 조사였다. 급속 열처리 온도에 관계없이 모든 적색 형광체 박막은 622 nm에 피크를 갖는 적색 발광을 나타내었고, 열처리 온도가 $400^{\circ}C$에서 $550^{\circ}C$로 증가함에 따라 적색 발광 스펙트럼의 세기는 감소하는 경향을 보였다.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.305-310
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• 2008

Wireless telecommunication frequency band becomes wider with the development of modern telecommunication technology, and highly integrated semiconductors are applied more at high speed tain system. RFI susceptibilities of the integrated power semiconductors in high speed train system influence much on the system safety. RFI susceptibility standards and measurement methods in high speed train system at wireless telecommunication frequency band is surveyed in this research.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.85-87
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• 2004

We fabricated flexible thermoradiotherapy probes to alternated combination with Interstitial hyperthermia and Brachyradiotherapy thermoradiotherapy probe was coated by gold plate on polyethylene brachytherapy probe. When Agar phantom was heated 15 minute with 30 W radiofrequency power, temperature increased as 5oC for polyethylene probe and 20oC for gold coated polyethylene probe. We observed that the 1 cm square array would heat a volume with a 1.25 cm radius circular field cross section to therapeutic temperatures (90% relative SAR using Tm) and the 2 cm square array with a 1.75 cm radius rectangular field with central inhomogeneity. With 2 cm long electrode implants, we observed that the 1 cm square array would heat a 3 cm long sagittal section to therapeutic temperature (90% relative SAR using Tm). The histopathological changes associated with RF heating of normal canine brains have been correlated with thermal distributions. RF needle electrode heating was applied for 50 min to generate tissue temperatures of 43${\circ}$C. We obtained a quarter of the heated tissue material immediately after heating and sacrificed at intervals from 7${\sim}$30 days. The acute stage was demonstrated by liquefactive necrosis, pyknosis of neuronal element in the gray matter. Mild gliosis occurring around the necrosis was demonstrated in the last sacrificed (days30)canine brain.