• Journal of Communications and Networks
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• 제5권1호
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• pp.25-32
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• 2003

4G mobile communication system requires the throughput of 10-100Mbps. Adaptive modulated OFDM system is promising technique for increasing the throughput. In the pilot symbol assisted high-speed packet transmission system, the data symbol duration is generally considered to be small compared to the coherence time. However, OFDM symbol duration is longer than the symbol duration of a single carrier system, so that the packet duration of the pilot symbol assisted high speed packet transmission system is long. In this case, the change of channel conditions is too fast to be accurately estimated by channel estimator at the receiver in high Doppler frequency, so that many errors occur during demodulation, especially with the data symbols at the end of each packet. In this paper, we consider the BER at various instantaneous $E_b/N_o$ that includes the demodulation errors in high Doppler frequency. When the coherence time is ten times longer than the duration of a single packet, the channel can be closely approximated as an AWGN channel. Otherwise, the approximation breaks down and the above-mentioned errors that occur during demodulation must be taken into consideration. In this paper, we propose the pilot symbol assisted high speed packet transmission system based on adaptive OFDM using a novel lookup table to consider the demodulated errors and evaluate the throughput performance.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.755-757
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• 2009

Since the research of advanced terrestrial digital multimedia broadcasting system is still in progress, and in our previous paper, in which we introduced how to combine one conventional transmitted symbol with two additional bits to form a new symbol transmission, the bit error performance of LP bits is not realizable, because even we implemented the turbo code to protect the LP bits transmission, to obtain a certain good bit error probability, the value of $E_b/N_0$ cost highly. In this paper, we modified the composition of low-priority symbol and high-priority symbol, and through the system presented in previous paper we get a better simulation result of the LP symbol transmission.

• 디지털산업정보학회논문지
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• 제6권3호
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• pp.211-219
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• 2010

This paper designs the dynamic symbol automatic trading system in Korean option market. This system is based on Multichart program which is convenient and efficient system trading tool. But the Multichart has an important restriction which has only one constant symbol per chart. This restriction causes very useful strategies impossible. The proposed design uses global variables, signal chart selection and position order exchange. So an automatic trading system with dynamic symbol works on Multichart program. To verify the proposed system, BS(Buythensell)-SB(Sellthenbuy) strategies are tested which uses the change of open-interest of stock index futures within a day. These strategies buy both call and put option in ATM at start candle and liquidate all at 12 o'clock and then sell both call and put option in ATM at 12 o'clock and also liquidate all at 14:40. From 23 March 2009 to 31 May 2010, 301-trading days, is adopted for experiment. As a result, the average daily profit rate of this simple strategies riches 1.09%. This profit rate is up to eight times of commision price which is 0.15 % per option trade. If the method which raises the profitable rate of wining trade or lower commission than 0.15% is found, these strategies make fascinated lossless trading system which is based on the proposed dynamic symbol automatic trading system.

• 한국전자파학회논문지
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• 제19권4호
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• pp.461-469
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• 2008

본 논문은 MIMO OFDM 시스템에 적용 가능한 하이브리드 심볼 옵셋 추정 알고리즘을 제안한다. MIMO OFDM 시스템은 다중 송수신 안테나 시스템이므로 종래의 단일 송수신 안테나 시스템에 적용되는 알고리즘과는 다르게 다중 수신 안테나 시스템에서 사용하는 결합 기법을 고려하여 사용할 수 있다. 따라서 본 논문에서는 MIMO OFDM 시스템과 같은 다중 수신 안테나 시스템에서 적용 가능한 심볼 옵셋 추정 알고리즘을 제안하고, MIMO 시스템 환경에서 모의 실험하였으며, ISI가 심한 채널의 경우에는 제안하는 동일 이득 결합 상관 관계 알고리즘이 종래의 이른 심볼 옵셋 추정 알고리즘보다 이상적인 샘플 위치를 찾는 성능이 1.8배 우수함을 제시하였다.

• 대한산업공학회지
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• 제27권3호
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• pp.305-314
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• 2001

In this paper, we construct an automatic evaluation system of psychological feeling for corporate identity (CI) symbol mark based on a fuzzy neural network technique. The system is modelled by trainable fuzzy inference rules with several input variables (qualitative and quantitative design components of CI symbol mark) and a single output variable (consumer's feeling). The back propagation learning algorithm, which is a conventional learning method of multilayer feedforward neural networks, is used for parameter identification of the fuzzy inference system. The learning ability to train data and the generalization ability to test data are evaluated for the proposed evaluation system by computer simulations.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.398-402
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• 2008

Cyclic prefix (CP) is one of the most important technique to OFDM system and is reducing inter-symbol interference (ISI) effects in high speed wireless mobile communication system. At the time varying channel condition, however, fixed CP length is not only increasing power consumption but also reducing data transmission rate. So in this paper, we propose the system that has adaptive CP length for high speed data transmission system. We don't control CP length of every symbol but adjust symbol interval depending on channel condition to CP reconstruction.

• 한국전자파학회지:전자파기술
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• 제4권3호
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• pp.54-62
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• 1993

이 논문에서는 다중 TCM (Multiple Trellis-Coded Modulation, MTCM)을 적용하여 변조 시스템의 성능 을 향상 시컨 트렐리스 부호화된 8DPSK를 구성하고 그 성능을 분석한다. 또한 BER(Bit Error Rate)의 향상 을 위해 다중 심볼 차동 검파 방식을 적용한다. 모탤링한 채덜은 디지틀 위성 이동 통신 채널인 라이시안 페이 딩(Rician fading) 채널이다. 디코딩 방볍은 비터비 알고리듬을 사용하며, 연집 에러에의한 비터비 디코더의 에러 전파를 막기위해 인터리빙을 사용한다. 컴퓨터 시율레이션올 통하여 다중 TCM파 다중 심벌 차동 겁파를 적용한 트렐리스 부호화된 8DPSK는 동일한 대역폭 효율을 갖는 부호화되지 않은 차동 변조 방식보다 향상된 성능을 보임을 알 수 있다. 또한 페이딩 환경에서는 인터리빙 방법이 성능 향상에 중요함을 알 수 있다.

• 한국콘텐츠학회논문지
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• 제6권8호
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• pp.1-7
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• 2006

본 논문에서는 휴대인터넷 단말기의 전력소모를 최소화하여 Wibro 서비스를 제공받은 단말기의 사용시간을 증가시킬 수 있는 방안을 제안한다. 이에 Wibro 시스템의 전력소비량을 분석하였고 분석된 결과를 바탕으로 전력소모량을 감소시킬 수 있는 방안을 제시하였다. 제안된 시스템은 Symbol의 pilot수를 제어하여 단말기의 전력소모를 개선하는 방법으로 시뮬레이션을 통하여 성능을 분석하였다. 성능분석결과 제안된 방식을 사용하면 pilot수를 일정하게 보내는 기존의 시스템에 비하여 Symbol 당 pilot 수가 10% 감소하면 0.48dBm, 20% 감소하면 0.95dBm의 CINR을 감소시켜 단말기의 전력소비량을 감소시킬 수 있는 것으로 분석되었다.

• 한국의류학회지
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• 제33권8호
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• pp.1241-1252
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• 2009

This study is on the internal and external characteristics along with the phenomena of dress and ornaments expressed in them by analyzing Re-orienting Fashion (which is a system of signs and symbols) based on the theories of semiology in the search for the Korean identity by examining a Re-orienting Fashion that is being reinterpreted. Re-orienting Fashion performs the role of signs that act in the spread of Oriental culture through the globalization of traditional dress and ornaments in the Orient. It also has a meaning that converts the world of fashion to a new direction. When analyzing the system of signs and symbols in Re-orienting Fashion (based on the theories of semiology) the conclusions are that an eclectic symbol system has been formed by the combination of the pursuit of modernization in traditional dress and ornaments with post-modernism. A nature-friendly symbol system has been shaped as a natural silhouette in terms of the combination with Eastern philosophy that searches for a harmony with nature according to ecological trends. The ideal of a symbol system means the introduction of design elements in traditional dress and ornaments of the East as a rejection of Western civilization and as an alternative to the fixed pattern of the West.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.2059-2062
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• 2002

For detection of digitally modulated signals, the receiver must be provide with accurate carrier phase and symbol timing estimates. So far, tots of algorithms have been suggested for those purposes. In general, a interpolation filter with TED(Timing Error Detection) like Gardner algorithm is popularly used for symbol timing estimate of digital communication receiver. Apart from the performance point of view, a multiplicative operation of any interpolation filter limits the symbol rate of the system. Hence, we suggest a new symbol timing estimate algorithm for high speed burst-mode fixed wireless communication system and analyze its performance in the AWGN channel.