• ETRI Journal
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• 제45권5호
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• pp.899-909
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• 2023

In mobile communication, the most exploratory technology of fifth generation is massive multiple input multiple output (MIMO). The minimum mean square error and zero forcing based linear detectors are used in multiuser detection for MIMO single-carrier frequency division multiple access (SCFDMA). When the received signal is detected and regularization sequence is joined in the equalization of spectral null amplification, these schemes experience an error performance and the signal detection assesses an inversion of a matrix computation that grows into complexity. Ordered successive interference cancelation (OSIC) detection is considered for MIMO SC-FDMA, which uses a posteriori information to eradicate these problems in a realistic environment. To cancel the interference, sorting is preferred based on signal-to-noise ratio and log-likelihood ratio. The distinctiveness of the methodology is to predict the symbol with the lowest error probability. The proposed work is compared with the existing methods, and simulation results prove that the defined algorithm outperforms conventional detection methods and accomplishes better performance with lower complication.

• 한국전자파학회논문지
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• 제26권11호
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• pp.999-1011
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• 2015

전자전(Electronic Warfare) 상황에서 레이다는 재머에 의해 전파교란공격(ECM: Electronic Counter Measures)을 받게 된다. Linear-FM 신호는 도플러 특성이 우수하고, 신호의 구현이 용이하여 레이다에서 주로 사용되어 왔지만, 반복된 패턴에 의해 피탐 확률이 높고, 신호 특성변수 추정이 가능하여 기만재밍에 취약하다. 최근 제안된 APCN(Advanced Pulse Compression Noise) 신호는 랜덤 진폭과 랜덤 위상코드로 이루어진 신호로서, 저피탐 성능이 우수한 신호이다. 하지만, APCN 신호를 비롯한 일반적인 위상코드 신호는 도플러 특성이 좋지 않으므로, 주파수 천이에 의해 신호수신 성능이 저하될 수 있다. 따라서 본 논문에서는 도플러 특성을 개선하기 위한 방안으로 랜덤 위상천이 및 부호율 천이(RPCR: Random Phase and Code Rate transition) 레이다 신호 파형을 제안하고, 도플러 성능과 저피탐 성능을 분석하였다. Ambiguity 함수를 이용하여 부호율 천이에 의한 도플러 특성 개선을 제시하며, WHT(Wigner-Hough Transform)을 이용한 신호 특성 변수 추정 실험을 통해 RPCR 신호의 저피탐 성능을 분석하고, 전파교란대응책(ECCM: Electronic Counter Counter Measures)으로의 가능성을 확인한다.

• 한국통신학회논문지
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• 제40권5호
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• pp.924-930
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• 2015

본 논문에서는 잡음 환경에서 적은 연산량으로 소형 음향기기의 음질 향상을 위한 새로운 저연산 이득 제어 알고리즘을 제안한다. 대표적인 소형 음향기기인 보청기의 이득 제어 알고리즘은 입력 신호를 잡음 제거 한 후 이 신호의 파워를 기준으로 광역동범위압축 (wide dynamic range compression, WDRC)을 하기 때문에 불필요한 신호까지 증폭된다. 제안된 이득 제어 알고리즘은 음성 검출기 (voice activity detection, VAD)의 결과를 이용하여 음성의 존재 유/무에 따라 적응적으로 이득을 제어한다. 성능 평가를 위해 제안된 알고리즘은 VAD를 적용하지 않은 알고리즘과 정상 및 비정상 잡음환경에서 다양한 조건을 부과하여 비교하였으며, 실험결과 제안된 알고리즘이 전체 성능 및 잡음 구간에서 향상된 결과를 보였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.782-787
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• 2004

Internet Engineering Task Force (IETF) has been considering the deployment of the Random Early Detection (RED) in order to avoid the increasing of packet loss rates which caused by an exponential increase in network traffic and buffer overflow. Although RED mechanism can prevent buffer overflow and hence reduce an average values of packet loss rates, but this technique is ineffective in preventing the consecutive drop in the high traffic condition. Moreover, it increases a probability and average number of consecutive dropped packet in the low traffic condition (named as "uncritical condition"). RED mechanism effects to TCP congestion control that build up the consecutive of the unnecessary transmission rate reducing; lead to low utilization on the link and consequently degrade the network performance. To overcome these problems, we have proposed a new mechanism, named as Extended Drop slope RED (ExRED) mechanism, by modifying the traditional RED. The numerical and simulation results show that our proposed mechanism reduces a drop probability in the uncritical condition.

• Archives of Plastic Surgery
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• 제32권4호
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• pp.543-546
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• 2005

Pulmonary embolism is a one of the major cause of postoperative death. Surgery predisposes patients to pulmonary embolism, even as late as one month after the operation. The accurate detection of pulmonary embolism remains difficult, and the differential diagnosis is extensive. The prevention of pulmonary embolism is thus of paramount importance. We report a case of pulmonary embolism after coverage of pressure sore on the left ischium on the 8th day after operation. The patient was 60 years old, a severe smoker, in the high quantity of body mass index and had hypertension. The risk factors are 60 years of age or older who were in the highest quantity of body mass index. Heavy cigarette smoking and high blood pressure are also identified as risk factors. Plastic surgeons should keep the probability of pulmonary embolism development after operation in mind. When taking history, the risk factors should be checked certainly. The immobilization may explain the probability of pulmonary embolism development. Therefore absolute bed rest or positional maintenance should be avoided. Until recently, low molecular weight heparin has been used for preoperative prophylaxis. Plastic surgeons should be concerned in low molecular weight heparin for prophylaxis of the pulmonary embolism and study the indications and effectiveness in liposuction or abdominoplasty.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.754-756
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• 2013

최근 전자전(Electronic Warfare)에서는 기존 레이더 신호와는 다른 펄스 내 변조의 특성을 가지고 있는 저피탐확률 (LPI : Low Probability Intercept) 레이더가 도입/운용되고 있는 추세이다. 이러한 LPI 레이더를 탐지하기 위하여 본 논문에서는 펄스 내 변조를 식별하는 방법을 기술한다. 특히 레이더 펄스 내 변조 형태 중, 다양한 주파수 변조 패턴을 가지고 있는 FM(Frequency Modulation) 계열의 변조 형태를 식별하는 방법과 식별에 활용되는 특징인자를 제안하는데 초점을 맞추고 있으며, 이렇게 제안된 식별 방법 및 특징인자는 MathLab을 통해 성능을 검증하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권5호
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• pp.1049-1068
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• 2011

In this paper a simple and effective call admission control (CAC) scheme is proposed for the emerging interleave-division multiple-access (IDMA) systems, supporting a variety of traffic types and offering different quality of service (QoS) requirements and priority levels. The proposed scheme is signal-to-interference-plus-noise ratio (SINR) evolution based CAC (SE-CAC). The key idea behind the scheme is to take advantage of the SINR evolution technique in the process of making admission decisions, which is developed from the effective chip-by-chip (CBC) multi-user detection (MUD) process in IDMA systems. By virtue of this semi-analytical technique, the MUD efficiency can be estimated accurately. Additionally, the computational complexity can be considerably reduced. These features make the scheme highly suitable for IDMA systems, which can combat intra-cell interference efficiently with simple CBC MUD. Analysis and simulation results show that compared to the traditional CAC scheme considering MUD efficiency as a constant, the proposed SE-CAC scheme can guarantee high power efficiency and throughput for multimedia traffic even in heavy load conditions, illustrating the high efficiency of CBC MUD. Furthermore, based on the SINR evolution, the SE-CAC can make accurate estimation of available resource considering the effect of MUD, leading to low outage probability as well as low blocking and dropping probability.

• 한국게임학회 논문지
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• 제11권2호
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• pp.13-18
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• 2011

시드마이어에 의하면 게임은 일련의 흥미로운 선택들이라고 하였다. 이는 흥미로운 선택들이 게임을 재미있게 만드는 주요 요인이란 의미이다. 본 논문에서는 게임에서 존재하는 흥미롭지 않는 선택대안을 게임플레이의 전략적 오류라 정의하고 이들 오류를 검출하는 방법을 제안하였다. 제안하는 방법은 게임이론에서 게임을 표현할 때 사용하는 보수행렬들을 검사하여, 게임플레이의 전략적 오류를 검출하는 방법이다. 이 방법은, 게임의 보수행렬들만 검사하는 경우에는, 적절한 대응전략이 없는 선택, 절대 우위 선택, 절대 열등 선택, 그리고 비슷한 보상이 이루어지는 선택들의 오류들을 검출할 수 있다. 그리고 게임의 보수행렬들과 대응하는 사용빈도율들을 함께 사용하는 경우에는, 추가적으로, 기대 보수가 매우 낮은 선택, 기대 보수가 매우 높은 선택, 사용확률이 매우 낮은 선택 그리고 사용확률이 매우 높은 선택들의 오류들을 검출할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권2호
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• pp.676-692
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• 2018

Saliency detection in neurobiology is a vehement research during the last few years, several cognitive and interactive systems are designed to simulate saliency model (an attentional mechanism, which focuses on the worthiest part in the image). In this paper, a bottom up saliency detection model is proposed by taking into account the color and luminance frequency features of RGB, CIE $L^*a^*b^*$ color space of the image. We employ low-level features of image and apply band pass filter to estimate and highlight salient region. We compute the likelihood probability by applying Bayesian framework at pixels. Experiments on two publically available datasets (MSRA and SED2) show that our saliency model performs better as compared to the ten state of the art algorithms by achieving higher precision, better recall and F-Measure.

• Journal of information and communication convergence engineering
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• 제13권4호
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• pp.241-247
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• 2015

Cognitive radio has been attracting increased attention as an effective approach to improving spectrum efficiency. One component of cognitive radio, spectrum sensing, has an important relationship with the performance of cognitive radio. In this paper, after a summary and analysis of the existing spectrum-sensing algorithms, we report that the existing eigenvalue-based semi-blind detection algorithm and blind detection algorithm have not made full use of the eigenvalues of the received signals. Applying multi-antenna systems to cognitive users, we design a variety of spectrum-sensing algorithms based on the joint distribution of the eigenvalues of the received signal. Simulation results validate that the proposed algorithms in this paper are able to detect whether the signal of the primary user exists or not with high probability of detection in an environment with a low signal-to-noise ratio. Compared with traditional algorithms, the new algorithms have the advantages of high detection performance and strong robustness