• 대한전자공학회논문지
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• 제21권1호
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• pp.71-78
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• 1984

본 논문에서는 ADPCM 시스템의 noisy channel에서의 성능 개선을 위한 새로운 방법을 제시하였다. 이 방법은 robust quantiser를 사용하면서 주기적으로 maximum step sixte를 수신측에 보내준다. 또한 수신측 버퍼에서는 MSB 에러검출·수정을 행한다. Noisy channel 상태에서 실제의 음성에 대해 컴퓨터 시뮬레이션한 결과 제안된 시스템의 성능은 원래의 ADPCM의 성능보다 크게 향상되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.84-86
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• 2006

An informed watermarking algorithm is proposed in this work that aids in concealing packet loss errors in video communications. This watermark-based error concealment(WEC) method embeds a low resolution version of the video frame inside itself as watermark data. At the receiver, the extracted watermark is used as a reference for error concealment. The proposed DCT-based algorithm has features of informed watermarking in order to minimize the distortion of the host frame. At the encoder, a predictive feedback loop Is employed which helps to adjusts the strength of the scale factor Furthermore, some of the modified coefficients of the DCT signal are virtually free from distortion by employing bit- sign adaptivity. The performance of the detector is Qualitatively analyzed for error concealment applications where full-frame DCT embedding proved to be more advantageous.

• The Journal of the Acoustical Society of Korea
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• 제15권3E호
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• pp.13-18
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• 1996

A real-time identifier for the nonstationary time-varying signals and systems was implemented using a low cost DSP (digital signal processing) chip. The identifier is comprised of I/O units, a central processing unit, a control unit and its supporting software. In order t estimate the system accurately and to reduce quantization error during arithmetic operation, the firmware was programmed with 64-bit extended precision arithmetic. The performance of the identifier was verified by comparing with the simulation results. The implemented real-time identifier has negligible quantization errors and its real-time processing capability crresponds to 0.6kHz for the nonstationary AR (autoregressive) model with n=4 and m=1.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2006년도 한국컴퓨터종합학술대회 논문집 Vol.33 No.1 (A)
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• pp.340-342
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• 2006

기존의 멀티미디어 통신 프로토콜은 무선 네트워크 환경에서의 많은 오류에 대한 고려를 하지 않기 때문에 데이터의 손실이 커지고 신뢰성이 보장하기 위한 방법의 사용으로 인해 오버헤드가 커지는 문제가 있다. 3G-324M 프로토콜은 이러한 무선 네트워크 환경에서 멀티미디어 통신 시 사용되는 프로토콜이다. 하지만 오류 발생이 기변적으로 변하는 상황에 대해서 적절칩 대처하지 못하는 단점이 있다. 본 논문에서는 기존의 3G-324M 프로토콜을 확장하여, 무선 네트워크라는 오류 발생이 많은 상황에서 이러한 단점을 적절히 대처할 수 있는 프로토콜 설계 요소 및 그와 관련된 구현 방법에 관해 논한다. 제안한 방법을 검증하기 위해 프로토콜에 수신된 데이터의 오류를 예측하는 모듈을 추가해 오류 발생 정도를 예측하고 송신하는 데이터를 이러한 상황에 적절하게 대처해 송신할 수 있도록 하였고 그에 따른 테스트 결과를 살펴본다.

• 대한수학교육학회지:학교수학
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• 제1권2호
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• pp.571-588
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• 1999

Our mathematical curriculum has been revised frequently compared to another countries. The frequent revisions may mean that the current curriculum is not so complete in the selected contents of each grade levels. The idea is partially supported by the fact that the didactics of mathematics has both hypothesis-deductive and hypothesis-constructive property. Investigating the items which are used in TIMSS study and based on the relatively common curriculums of 40 more countries, the styles of them are a bit different from those of our textbooks of primary and secondary school. Hence, we consider that the construction and implementation of our mathematical curriculum may be a large scale of experiment for the improved curriculum carried by the nation. Additionally, we propose less compulsive curriculum than the current for minimizing the possible trial and errors.

• 한국통신학회논문지
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• 제22권7호
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• pp.1477-1486
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• 1997

Conventioally the decoding methods and the design of coset codes for burst synchronization and error detection have been based on the concept that slips occuring to the right or to the left with respect to a reference timing are corrected. In this paper we newly approach to the design of coset codes relying on the condition that only a single code word can exists in an observation interval, which provides an extentended view on the conventional approach. A theorem concerning the condition is presented. A combined burst synchronization and error detection system with maximum slip correction capability have been devised based on the theorem and a detection method is falsely accepted in the presented of channel errors. The false acceptance probabilities of the system are derived and its performance is analyzed through computer computation using the derived results.

• 반도체디스플레이기술학회지
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• 제19권3호
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• pp.112-117
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• 2020

NAND flash memory is a non-volatile memory that retains stored data even without power supply. Internal memory used as a data storage device and solid-state drive (SSD) is used in portable devices such as smartphones and digital cameras. However, NAND flash memory carries the risk of electric shock, which can cause errors during read/write operations, so use error correction codes to ensure reliability. It efficiently recovers bad block information, which is a defect in NAND flash memory. BBT (Bad Block Table) is configured to manage data to increase stability, and as a result of experimenting with the error correction code algorithm, the bit error rate per page unit of 4Mbytes memory was on average 0ppm, and 100ppm without error correction code. Through the error correction code algorithm, data stability and reliability can be improved.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.49-50
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• 2006

Digital satellite systems are usually integrated with terrestrial systems to provide various services, and in these cases they should satisfy the performance objectives defined by the terrestrial systems. Recommendation ITU-R S.1062 specifies the performance of digital satellite systems. The performance objectives were given in terms of bit error probability divided by the average number of errors per burst versus percentage of time. This paper presents theoretical method to estimate performance measure of digital satellite systems defined in Recommendation ITU-R S.1062. We show performance estimation results of duo-binary Turbo codes, and verify them by comparing to the simulation results.

• 한국전자파학회논문지
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• 제12권3호
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• pp.470-477
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• 2001

Multucarrier code-division multiple access(MC-CDMA) is one of the promising technique for high capacity wireless communication. Hower the carrier phase error and frequency offest cause the performance degradation of MC-CDMA due to the inter-carrier interference. In this work, downlink performance of the partially coherent MC-CDMA is analytically derived in Rayleigh fading channels. The bit error rate sensitivity by combining method, Maxiaml ratio combining (MRC)and Equal gain combining(EGC), is compared as functions of phase errors. multi-user interference, and received signal-to-noise ratio. The results show that the susceptibility for the performance degradation of EGc and MRC is negligible for loop SNR's of above 15 dB and above 10 dB, respectivtely.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.458-461
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• 2000

Variable length codes are often used in entropy coding, but are very vulnerable in noisy environments. Reversible variable length codes, however, muse possible to decode instantaneously in both forward and backward directions, so that more usable data can be retrieved when bit errors occur via transmission. Furthermore, partial decodability is desirable to introduce in the reversible variable length code because ROI (Region Of Interest) decoding function is sometimes required in recent image information systems such as the medical imaging, the digital museum and so on. In this paper, we propose a partially decodable and reversible variable length code by modifying Golomb-Rice code.