• 한국통신학회논문지
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• 제35권6C호
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• pp.516-522
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• 2010

본 논문에서는 중국향 휴대이동방송인 CMMB(China multimedia mobile broadcasting)를 위한 소수배 주파수 동기와 정수배 주파수 오차 추정 알고리듬을 제안한다. 제안한 소수배 주파수 동기 알고리듬은 CMMB의 프레임 구조에 가장 적합하도록 전치부호를 활용하여 매 CMMB 심볼마다 추정이 가능하다. 또한 제안된 정수배 주파수 알고리듬은 CMMB 동기 신호를 이용하여 매 프레임마다 추정 한다. 제안 알고리듬은 시간 오프셋이 존재할 때에도 소수배와 정수배 주파수 오프셋을 정확히 추정할 수 있으며 다중 경로 상황에서도 우수한 성능을 보인다.

• 조명전기설비학회논문지
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• 제29권8호
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• pp.23-31
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• 2015

This paper proposes an advanced distance relaying based on the DC offset removal filter to minimize the effects of DC offset on a double circuit transmission line. The proposed DC offset removal filter uses only one cycle of data for phasor extraction computation, which does not need to preset the time constant of the DC offset component. This proposed distance relaying uses not only the residual current of the faulted circuit but also mutual current of the healthy adjacent circuit. A series of off-line test results using ATP simulation data show the effectiveness of the an advanced distance relaying.

• 공학기술논문지
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• 제7권3호
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• pp.131-135
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• 2014

In this paper was proposed a flux offset-type fault current limiter as means of reducing fault currents. To secure the operation reliability of a flux offset-type fault current limiter, constructed a simulation system to analyze its operation characteristics by generating a double line-to-line fault. According to the test results, the system performed stably without any impedance. However, when an accident occurred, the flux-offset of magnetic was not occurred. Because of this, any impedance occurred at circuit. It was confirmed that the impedance was low and fast to limit the fault current. At this time, the fault current limited rate was about 95%.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.455-456
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• 2008

New CMOS ROM cell is reported in this paper, distinguished from conventional ones in that it can be re-programmed by multi-times. It uses the comparator offset as the physical storage quantity and the MOSFET FN stress effect for offset programming. It demands very low offset for read, and works well in very low voltage. It can become a promising ROM solution for various SoC systems.

• 대한전자공학회논문지TC
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• 제47권10호
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• pp.1-7
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• 2010

본 논문에서는 정합필터 기반의 IEEE 802.15.4a chirp spread spectrum (CSS)을 위한 새로운 주파수 오프셋 추정 알고리즘을 제안한다. 기존의 주파수 오프셋 추정 알고리즘은 연속되는 동일한 심볼 간의 차등 위상을 계산함으로서 주파수 오프셋을 추정하였다. 하지만 CSS는 긴 십볼 구간과 가드 구간을 포함하고 있어 기존의 방법으로 주파수 오프셋을 추정하였을 경우 위상 모호성이 발생한다. 특히 정합필터 기반 수신기 구조에서 위상 모호성을 해결하지 않는다면 주파수 오프셋에 의한 정현파 간섭 현상으로 정합필터의 성능이 감소하게 된다. 따라서 본 논문에서는 위상 모호성을 해결하기 위해 정수부와 소수부 주파수 오프셋 추정을 분할화 하여 주파수 오프셋을 추정하는 새로운 알고리즘을 제안한다. 제안하는 알고리즘은 sub-chirp 간 정합필터 결과의 차등 위상을 계산 한 결과와 기존의 심볼 간 차등 위상 정보를 이용하여 정수부 주파수 오프셋을 추정하여 위상 모호성을 제거 한 후, 심볼 간 차등위상 정보를 통하여 소수부 주파수 오프셋을 추정한다. 시뮬레이션 결과 제안하는 알고리즘은 정수부 주파수 오프셋 추정을 통해 위상 모호성 문제를 해결할 수 있음을 확인하였고 위상 모호성 이 발생하지 않는 경우에서도 기존의 알고리즘과 거의 통일한 성능을 보임을 확인하였다.

• Journal of Communications and Networks
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• 제8권2호
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• pp.234-240
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• 2006

We study the dynamic burst assembly based on traffic prediction and offset and delay differentiation in optical burst switching network. To improve existing burst assembly mechanism and build an adaptive flexible optical burst switching network, an approach called quality of service (QoS) based adaptive dynamic assembly (QADA) is proposed in this paper. QADA method takes into account current arrival traffic in prediction time adequately and performs adaptive dynamic assembly in limited burst assembly time (BAT) range. By the simulation of burst length error, the QADA method is proved better than the existing method and can achieve the small enough predictive error for real scenarios. Then the different dynamic ranges of BAT for four traffic classes are introduced to make delay differentiation. According to the limitation of BAT range, the burst assembly is classified into one-dimension limit and two-dimension limit. We draw a comparison between one-dimension and two-dimension limit with different prediction time under QoS based offset time and find that the one-dimensional approach offers better network performance, while the two-dimensional approach provides strict inter-class differentiation. Furthermore, the final simulation results in our network condition show that QADA can execute adaptive flexible burst assembly with dynamic BAT and achieve a latency reduction, delay fairness, and offset time QoS guarantee for different traffic classes.

• 한국정밀공학회지
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• 제30권6호
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• pp.578-583
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• 2013

The lighting devices using organic light emitting diodes (OLEDs) are actively researched because of the various advantages such as high power efficiency and 2-dimensitonal lighting emitting. To commercialize those OLED lighting devices, the manufacturing cost must be downed to comparable price with conventional light sources. Here, we demonstrate a reverse gravure-offset or gravure off-set printed metal electrode for the auxiliary electrode for OLED lighting devices. For the fabricated OLED's auxiliary electrode, we used Ag nano-paste and printed metal grid structure with a line width and spacing of several ten and hundred micrometer by using gravure-offset printing. In the end the printing metal grid pattern are successfully achieved by optimization of various experimental conditions such as printing pressure, printing speed and printing delay time.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권2호
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• pp.601-617
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• 2014

In digital radio broadcasting systems, long delays are incurred in service start time when tuning to a particular frequency because several synchronization steps, such as symbol timing synchronization, frame synchronization, and carrier frequency offset and sampling frequency offset compensation are necessary. Therefore, the operation of the synchronization blocks causes delays ranging from several hundred milliseconds to a few seconds until the start of the radio service after frequency tuning. Furthermore, if spectrum inversed signals are transmitted in digital radio broadcasting systems, the receivers are unable to decode them, even though most receivers can demodulate the spectral inversed signals in analog radio broadcasting systems. Accordingly, fast synchronization techniques and a method for spectral inversion detection are required in digital radio broadcasting systems that are to replace the analog radio systems. This paper presents a joint detection method of frame, integer carrier frequency offset, and spectrum inversion for DRM Plus digital broadcasting systems. The proposed scheme can detect the frame and determine whether the signal is normal or spectral inversed without any carrier frequency offset and sampling frequency offset compensation, enabling fast frame synchronization. The proposed method shows outstanding performance in environments where symbol timing offsets and sampling frequency offsets exist.

• 한국소음진동공학회논문집
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• 제18권9호
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• pp.905-912
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• 2008

Notion sickness is well known to be caused by long time exposure to the very low frequency motion in the multiple axes of human body Since the vestibular system for the perception of low frequency motion is located in the head, accurate measurement of 6 degree of freedom head motion is of great importance. In this study, the measurement system consisting of a safety helmet and 9 translational accelerometers was constructed for the estimation of 3 translational and 3 rotational motions of human head. Since estimation errors of 3 rotational components can be significantly magnified even by small offset of the sensitivity axis from the geometric center of an accelerometer, accurate measurement of sensitivity axis must be preceded. The method for accurate estimation of the offset was proposed, and the effect of offset on the estimation of angular acceleration was investigated.

• 한국통신학회논문지
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• 제37C권10호
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• pp.894-900
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• 2012

실내 무선측위 시스템은 정확한 태그 위치를 측정하기 위하여 비콘의 거리 정보를 사용한다. 시스템은 비콘과 태그 사이의 거리를 추정하기 위해서, 독립적인 클럭 오프셋을 포함하는 각 비콘에 도착하는 태그 펄스의 시간 정보를 계산한다. 이러한 클럭 오프셋은 비콘의 측위와 위치 추정 성능에 심각한 영향을 미친다. 본 논문에서는 이러한 문제를 해결할 수 있는 클럭 오프셋 보정 기법을 제안한다. 제안하는 기법의 성능을 검증하기 위해여 랜덤하게 -1,000ppm~1,000ppm 사이의 클럭 오프셋을 가지는 상황에서 측위 실험을 진행하였으며, 모의실험 결과를 통하여 제안하는 기법이 클럭 오프셋 문제를 효율적으로 해결할 수 있음을 확인하였다.