• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.273-274
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• 2007

영상 신호에서 Dynamic Range는 이미지가 포함하고 있는 휘도의 최소 레벨과 최대 레벨의 비이다. 이미지 촬상 장치가 표현할 수 있는 Dynamic Range는 한정되어 있기 때문에 한정된 범위를 벗어나는 영역에 대해서는 이미지의 왜곡 혹은 손실이 발생한다. 본 논문에서는 Line별로 다른 Integration Time을 적용하는 방법으로 영상의 계조 표현 범위를 넓게 향상시켜 Wide Dynamic Range를 갖는 영상을 얻는 방법을 기술한다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.5
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• pp.338-345
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• 2002

The study presents a new testing and analysis method for brake judder on vehicle. For the identification of the excitation mechanism of a brake judder, it is necessary to measure the dynamic brake disc geometry during braking on vehicle. The non-contact sensor system was used to monitor the brake disc geometry. Brake torque variation (BTV) caused by disc thickness variation (DTV) is the primary excitation for brake judder. The mechanical effects generating BTV are linked not only to initial manufacturing tolerances but also to uneven wear. Therefore, the brake disc geometry should be strictly managed to initial condition. The aim of this study has been to measure the dynamic DTV and runout on vehicle and analyze the influence of test parameters on brake judder and compare the disc component with vehicle matching about the DTV Profile. As a result of this study, The amplitude of brake judder is proportional to vehicle speed and fluid pressure fluctuation on braking. The major sources of brake judder are directly related to disc thickness variation and side runout variation of corner assembly (disc, hub. bearing).

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.207-215
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• 2011

Due to the increasing availability and popularity of digital television (DTV), the numbers of TV channels and programs that can be selected by consumers are also increasing rapidly. Therefore, searching for interesting channels and program via remote controls or channel guide maps can be frustrating and slow. In this paper, in order to better satisfy consumers, we propose a dynamic channel surfing scheme that reduces the channel seek distance in DTV. The proposed scheme dynamically rearranges the channel sequences according to the channel currently being watched to reduce the channel seek distance. The results of a simulation experiment demonstrate that the proposed dynamic channel surfing scheme reduces the channel seek distance for DTV channel navigation when up-down channel selection interfaces are used.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.235-236
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• 2007

CCD(Charge-Coupled Device) 혹은 CMOS (Complementary Metal Oxide Semiconductor)와 같은 소자를 이용하여 빛을 전기적 신호인 Image로 재구성하는 촬상소자(Color Capture Device)는 촬영환경이 어두워지면 Dynamic Range가 작아지고, Noise가 상대적으로 심해진다[1][2]. 본 논문에서는 촬영 환경이 어두울 때, Resolution을 Preserving하는 Pixel Pitch가 큰 촬상 소자와 Motion Blur를 억제하는 Exposure Time이 긴 촬상 소자의 조합을 신호처리로 구현하여, 신호의 Power를 향상시켜 Dynamic Range를 키우고 Noise의 Boost-up을 억제하여 SNR(Signal to Noise Ratio)을 향상시키는 방식으로, 촬상 장치의 감도를 향상시켜 화질을 개선하는 방법을 제안한다.

• Journal of Broadcast Engineering
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• v.15 no.4
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• pp.555-562
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• 2010

After starting digital terrestrial broadcasting, there have been a number oftrials to provide new services like data broadcasting on a spare bandwidth of a DTV channel. Recently, the Push-VOD service, which provides A/V contents on that bandwidth, gets more attention and is being standardized as NRT(Non-Real-Time) by ATSC. However, it is highly probable that the contents transmitted in this way contain many errors due to the DTV receiving environment. Thus, in order to improve the reliability of transmission, the contents should be transmitted repeatedly several times, considering the unidirectional property of DTV terrestrial network. In this paper, we propose a method to calculate the optimal number of repetitions to transmit each contents in a way that minimizes the number of errors occured, when trying to transmit several contents to the receiver in a restricted time, using Markov-chain modeling and dynamic programming approach.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.646-653
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• 2007

This paper tries to find out how a household's purchase probability and purchase time changes as time passes. Previous studies show that a highly educated family with high income, which is usually an early adopter in a new product adoption, tends to be an early adopter of DTV. On the contrary, in the dynamic sense of diffusion, this study shows that an average household's purchase probability would become higher and its purchase time would come sooner than later, as price falls sharply. As time passes, it turns out that DTV is becoming a necessary good rather than a luxury good. Thus, in the future, either a household's popuation characteristics or information on new product are not expected to affect the probability of a household's purchasing DTV.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.2 s.332
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• pp.49-59
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• 2005

An adaptive hybrid beamformer is proposed to improve the reception performance of the advanced television system committee (ATSC) digital television (DTV) in a mobile environment. Dynamic multipaths and Doppler shifts severely degrade the reception performance of the ATSC DTV receiver. Accordingly, a hybrid beamformer, called a Capon and least mean square (CLMS) beamformer, is presented that uses direction of arrival (DOA) information and the least mean square (LMS) beamforming algorithm. The proposed CLMS algerian efficiently removes dynamic multipaths and compensates for the phase distortion caused by Doppler shifts in mobile receivers. After the CLMS beamformer is operated, the subsequent use of an equalizer removes any residual multipath effects, thereby significantly improving the performance of DTV receivers. The performances of the proposed CLMS, Capon, and LMS beamformersare compared based on computer simulations. In addition, the overall performance of the CLMS beamformer followed by an equalizer is also considered.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.281-284
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• 2004

This paper described an Enhanced-xVSB system for improving mobile/pedestrian reception performance to the ATSC DTV 8-VSB transmission standard. E-xVSB system can transmit a mixture of normal (8-VSB) stream and enhanced (robust) stream. The robust stream has a higher threshold of visibility (TOV) compared to the standard stream, and legacy receivers ignore the robust packets. Thus, Enhanced-xVSB system is fully backward compatible with a current ATSC standard. for mobile and portable reception support, E-xVSB system adopts a reduced constellation method as well as enhanced trellis-coded modulation scheme. E-xVSB system supports a variety of enhanced modulation schemes: Pseudo-2VSB, Enhanced-4VSB, modified Enhanced-8VSB and Hybrid-VSB. Proposed E-xVSB system performs well under serious dynamic multipath reception environment.

• Journal of Broadcast Engineering
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• v.10 no.1 s.26
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• pp.14-21
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• 2005

This paper described an Enhanced-xVSB system for improving mobile/pedestrian reception performance to the ATSC(Advanced Television System Committee) DTV 8-VSB transmission standard. E-xVSB system can transmit a mixture of normal (8-VSB) stream and enhanced (robust) stream. The robust stream has a higher threshold of visibility (TOV) compared to the standard stream, and legacy receivers ignore the robust packets. Thus, Enhanced-xVSB system is fully backward compatible with a current ATSC standard. For mobile and portable reception support, E-xVSB system adopts a reduced constellation methodas well as enhanced trellis-coded modulation scheme. E-xVSB system supports a variety of enhanced modulation schemes : Pseudo-2VSB, Enhanced-4VSB, modified Enhanced-8VSB and Hybrid-VSB. Proposed E-xVSB system performs well under serious dynamic multipath reception environment.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1213-1218
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• 2007

The brake judder comes from non-uniformities in the tire/wheel assembly caused by mechanical effects such as a brake torque variation (BTV). A disc thickness variation (DTV) related with the kinematic behavior of the disc was investigated a main source of BTV. In this study, a dynamic model with brake corner assembly of full vehicle using MSC.ADAMS was correlated by experiment of judder phenomenon. Judder was generated and correlated systematically by judder experiment in chassis and brake dynamometer from variation in the thickness of the disc. Also it has been found a judder transfer path and variation of the braking pressure. Through analysis of transfer function and movement of subsystem caused by BTV generation, design parameters have been found. Based on the results obtained from parameter study of suspension module, the effective design process and developed model with brake corner assembly was suggested for vibration reduction of steering wheel caused by the judder phenomenon.