• 한국통신학회논문지
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• 제24권6A호
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• pp.855-863
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• 1999

최근 들어 다양한 종류의 정보를 원하는 속도와 서비스품질(QOS)로 전송하고자 하는 Multi-Rate CDMA 시스템들에 대한 연구가 활발하다. 본 연구에서는 다양한 종류의 정보를 보내는데 있어서 쉽게 기존의 CDMA 시스템과 융화 될 수 있으며, 사용자가 요구하는 QOS와 전송 속도를 만족시킬 수 있는 Multi-Code CDMA 시스템에서 주요한 요소로 고려되고 있는 전력 증폭기의 비선형성을 고려하여 Multi-Code CDMA 시스템의 성능을 분석하였다. 분석에 사용한 비선형 증폭기의 모델링에는 다항식을 사용하였으며, 분석 결과 특히 주파수 선택적 페이딩의 경우 비선형에 의한 영향이 AWGN 채널에 비하여 훨씬 더 큼을 알 수 있었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.157-158
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• 2008

This paper examines an adaptive coding scheme for flat fading channels to maximize the average code rate of a coded system. The proposed adaptation technique is employed by using the required free distance of a rate compatible code depending on the channel realization. First, the system will calculate the required free distance based on the instantaneous channel gain. Based on this channel gain we will select a set of convolution code to optimize the code rate with a certain performance requirement. Simulation results show that our proposal can achieve a higher code rate.

• 한국통신학회논문지
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• 제39A권2호
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• pp.86-91
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• 2014

Holographic data storage (HDS) has a number of advantages, including a high transmission rate through the use of a charge coupled device array for reading two-dimensional (2D) pixel image data, and a high density capacity. HDS also has disadvantages, including 2d intersymbol interference by neighboring pixels and interpage interference by multiple pages stored in the same holographic volume. These problems can be eliminated by modulation codes. We propose a 7/9 error-correcting modulation code that exploits a Viterbi-trellis algorithm and has a code rate larger (about 0.778) than that of the conventional 6/8 balanced modulation code. We show improved performance of the bit error rate with the proposed scheme compared to that of the simple 7/9 code without the trellis scheme and the 6/8 balanced modulation code.

• 한국통신학회논문지
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• 제19권5호
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• pp.912-919
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• 1994

본 논문에서는 확대 Hamming 부호를 이용한 새로운 오류제어선로부호를 제안하고 그 성능을 분석한다. 제안된 부호는 최소 Hamming 거리가 4이므로 기본적으로 한개의 오류를 정정할 수 있고 두개의 오류를 검출한 수 있다. 또한 선로부호에 사용되는 여분의 비트를 이용하여 오류검출 능력을 증가시킬 수 있다. 결과적으로 제안된 부호는 Hamming (7.4) 부호를 이용한 기존의 오류정정선로부호에 비해 부호율은 다소 떨어지나 저주파대역에서의 스펙트럼 특성이 더 우수하며 더 적은 복호비트오율을 가진다.

• 한국통신학회논문지
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• 제39A권5호
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• pp.215-219
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• 2014

In holographic data storage (HDS), a high transmission rate is accomplished through the use of a charge coupled device array for reading two-dimensional (2D) pixel image data. Although HDS has many advantages in terms of storage capacity and data transmission rates, it also features problems, such as 2D intersymbol interference (ISI) by neighboring pixels and interpage interference (IPI) by multiple images stored in the same holographic volume. Modulation codes can be used to remove these problems. We introduce a 2D 8/9 error-correcting modulation code. The proposed modulation code exploits the trellis-coded modulation scheme, and the code rate is larger (about 0.889) than that of the conventional 6/8 balanced modulation code (an increase of approximately 13.9%). The performance of the bit error rate (BER) with the proposed scheme was improved compared with that of the 6/8 balanced modulation code and the simple 8/9 code without the trellis scheme.

• 한국의료질향상학회지
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• 제12권1호
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• pp.104-112
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• 2006

Background : The necessity of unify and standardize codes used at hospital has been emphasized since OCS (Order Communicating System) was adopted. Therefore, the purpose of this study were to standardize operation code by continuous training of the ICD-9-CM code that is used as standard code in OCS program at operating room. Method : In 400 operation data, operation code entered in OCS program at operating room was compared to operation name recorded in medical record. In addition, a matching rate between input data of operation code by medical record department and computing input data of operation code in 3,710 cases was compared for each department. User operation name and operation code were matched and major diagnosis by operation department and operation name were also matched. Results : User operation name was reflected in operation classification code in detail, and operation code entered on user was registered. Input rate and matching rate of operation code were gradually improved after improvement activity. In particular, a matching rate was high at ophthalmology where operation name is segmented. Plastic surgery and orthopedics with a lot of emergency operation and comprehensive operation name show low input rates. Conclusions : As the medical field makes progress in computerlization, awareness of information exchange and sharing becomes higher. Among codes to classified medical institution, codes related to surgical operation are all different by user of hospital and department. Computerlization and standardization is essential. And when efforts of standardization continue in alliance with individual hospital and institution, initiative of preparing medical policy data at a national level will be accelerated.

• 한국통신학회논문지
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• 제23권7호
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• pp.1659-1666
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• 1998

IMT-2000 시스템을 위한 전송 방식으로 활발히 연구되고 있는 다중부호 부호분할 다원접속 시스템은, 고속 데이터를 다수의 저속데이터로 병렬변환하고 이들 변환 신호를 직교 부호를 이용하여 구분한 뒤 동시 전송하는 방법이다. 이 논문에서는 부호율 r=1/2인 길쌈 부호와 이원 직교 부호를 이용함으로써, 기존의 시스템과 동일한 데이터 전송율과 처리이득을 유지하면서도 비트오율 성능을 월등히 개선하는 새로운 방식을 제안한다. 부가성 백색 정규 잡음 채널과 다중 경로 감쇄 채널에서 최대비 결합 갈퀴 수신기를 이용하는 동기식 시스템에 대한 모의 실험을 통해서 월등한 성능 향상이 가능함을 확인하였다.

• 한국통신학회논문지
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• 제32권10C호
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• pp.942-949
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• 2007

In this paper, we propose a new rate-control scheme, called splining, to construct low-rate codes from high-rate codes by splitting rows of the parity-check matrices of LDPC codes, which can construct rate-compatible LDPC codes having good initial transmission performance. Good low-rate codes can be constructed by making the number of distinct check node degrees as small as possible after splitting. The proposed scheme achieves good cycle property, low decoding complexity, and fast convergence speed, especially compared to the puncturing. Especially, rate-compatible repeat accumulate-type LDPC (RA-Type LDPC) code is constructed using splitting, which covers the code rates from 1/3 to 4/5. Through simulation it is shown that this code outperforms other rate-compatible RA-Type LDPC codes for all rates and can be decoded conveniently and efficiently.

• 방송공학회논문지
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• 제19권2호
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• pp.268-271
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• 2014

소스 부호 왜곡 모델 및 채널 유도 왜곡 모델 기반의 기존의 FEC 부호율 결정 기법들은 일반적으로 높은 계산 복잡도와 구현 비용을 요구하는 모델 파라메터 트레이닝 과정을 요구한다. 본 논문에서는 복잡한 모델링 과정을 피하기 위해서 최적의 FEC 부호율 결정을 위한 채널 손실 한계집합을 추정하기 위한 정확한 소스-채널 결합 왜곡 모델을 제안한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권10호
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• pp.2411-2429
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• 2013

In this paper, we extend the case of information exchange error mitigation for the distributed orthogonal space-time block code (DOSTBC) for two transmit antennas to distributed quasi-orthogonal space-time block code (DQOSTBC) for four transmit antennas. A rate 1 full-diversity DQOSTBC for four transmit antennas is designed. The code matrix changes according to different information exchange error cases, so full diversity is maintained even if not all information exchange is correct. We also perform analysis of the pairwise error probability. The performance analysis indicates that the proposed rate 1 DQOSTBC outperforms rate 1/2 DOSTBC for four transmit antennas at the same transmission rate, which is confirmed by the simulation results.