• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권12호
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• pp.5015-5027
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• 2015

Transceiver optimization in multiple input multiple output (MIMO) cognitive systems is studied in this paper. The joint transceiver beamformer design is introduced to minimize the transmit power at secondary base station (SBS) while simultaneously controlling the interference to primary users (PUs) and satisfying the secondary users (SUs) signal-to-interference-plus-noise ratio (SINR) based on the convex optimization method. Due to the limited cooperation between SBS and PUs, the channel state information (CSI) usually cannot be obtained perfectly at the SBS in cognitive system. In this study, both perfect and imperfect CSI scenarios are considered in the beamformer design, and the proposed method is robust to CSI error. Numerical results validate the effectiveness of the proposed algorithm.

• Journal of Korea Trade
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• 제26권7호
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• pp.43-58
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• 2022

Purpose - Based on the telecommunication service trade data of China, Japan, and South Korea from 2009 to 2019, this paper compares and analyzes the international competitiveness of the three countries' telecommunication service trade, and finds the existing problems in China through the comparison, so as to make reasonable planning and industrial development strategy, and find away to catch up. Design/methodology - The comparative analysis method was used to compare and analyze the international competitiveness of telecommunication service trade among China, Japan, and South Korea from the three aspects of market share, trade surplus, and export proportion represented by MS, TC, G-L, RCA, and CA. Findings - The international competitiveness of telecommunication service trade among China, Japan, and South Korea does not have competitive advantages. China is larger than Japan and South Korea, but only close to average globally, and its share of trade in telecommunications services is lower than Japan and South Korea's. Originality/value - This paper tries to explore international competitiveness in the field of telecommunication service trade, and through the comparison of five indicators to find problems in China, so as to put forward countermeasures to improve the international competitiveness of China's telecommunication service trade, and lay a foundation for subsequent research on the source factors of international competitiveness.

• Journal of electromagnetic engineering and science
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• 제16권3호
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• pp.143-149
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• 2016

This work presents a method used for designing a broadband class-E power amplifier that combines the two techniques of a nonlinear shunt capacitance and a low quality factor of a series resonator. The nonlinear shunt capacitance theory accurately extracts the value of class-E components. In addition, the quality factor of the series resonator was considered to obtain a wide bandwidth for the power amplifiers. The purpose of using this method was to produce a simple topology and a high efficiency, which are two outstanding features of a class-E power amplifier. The experimental results show that a design was created using from a 130 to 180 MHz frequency with a bandwidth of 32% and a peak measured power added efficiency of 84.8%. This prototype uses an MRF282SR1 MOSFET transistor at a 3-W output power level. Furthermore, a summary of the experimental results compared with other high-efficiency articles is provided to validate the advantages of this method.

• 한국음향학회지
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• 제34권1호
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• pp.82-91
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• 2015

본 논문에서는 음성 채널을 통해 데이터를 전송하기 위한 데이터 모뎀의 코드북 설계 방법에 대해 기술하였다. 제안한 코드북 설계 방법은 minimax 최적화 기법을 이용하여 탐색 공간에 분포하는 심볼들 중 최대 중첩을 갖는 심볼들의 중첩을 최소화하도록 하는 방법이다. 제안한 방법에 따라 설계된 코드북을 적용한 데이터 전송 시스템을 제시하였으며, 모의 실험과 실제 이동통신망 적용 실험을 통해 제안한 방법의 성능을 평가하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.219-219
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• 2010

In a past, the method in which it used the fluorescent material or it analyzes a gene was used in order to detect the Alzheimer's disease. However, in this paper, the magnetic bead is used in order to detect the Alzheimer's disease. The 'magnetic bead used in this paper is able to make the amyloid-beta and the selective binding known as cause of the Alzheimer's disease.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.679-682
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• 1999

This paper proposes the LSF or LSP that is the method of using to transfer the speech parameters after processed the speech to LPC, which is digital coding transferring efficiently, for the best quality and the lowest bit rate of parameters. The new revised transform algorithm between LSF and LPC coefficients is proposed. The proposed algorithm eliminates all multiplications, computes fewer operations, and reduces memory buffer sizes.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2006년도 가을 학술발표논문집 Vol.33 No.2 (D)
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• pp.699-704
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• 2006

무선 센서 네트워크는 소형의 무선 센서노드들로 구성된 네트워크이다. 무선으로 구성된 센서 네트워크는 사물과 환경의 변화를 감지하여 싱크로 전송하게 된다. 무선 센서 네트워크에서 센서노드는 무선으로 데이터를 전송할 때 가장 많은 에너지를 소모한다. 한정된 에너지 자원을 효율적으로 사용하기 위해서는 데이터 전송에 이용하는 라디오모듈의 사용을 최소화하여 네트워크 전체의 데이터 전송량을 감소시켜야 한다. 본 논문에서 제안하는 시스템은 에너지 소모를 줄이기 위해 DPCM, 웨이블릿, 양자화, 가변 길이 부호화를 사용하여 전송되는 데이터의 양을 줄여 라디오모듈을 통한 데이터 전송 횟수를 줄였고, 결과적으로 센서 네트워크의 트래픽을 감소시켜 에너지 소모를 줄였다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2005년도 하계학술대회
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• pp.255-258
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• 2005

광케이블의 분기나 이전 공사 시 광케이블을 적확히 식별할 필요성이 있다. 현재의 광케이블 식별 방법은 인력당김에 의한 원시적인 방법이나 전자기 유도를 이용하는 방법 등이 사용되고 있으나 인력과 시간이 많이 소모되고 식별 가능한 거리에도 한계가 있다. 본 논문에서 제시하는 광케이블 식별 방법은 맨홀 등에서의 현장 작업자가 식별코자 하는 광케이블을 두드리는 등의 교란을 가하고, 이러한 교란을 광섬유 간섭계를 통하여 추출하여 다시 현장의 작업자에게 통신 수단을 통하여 전송하여 줌으로써 작업자가 직접 자신이 가한 교란 신호와 추출된 신호간의 일치 여부를 판단함으로써 광케이블을 식별할 수 있도록 하는 것이다. 이 방법에 따르면, 원격지의 현장에서도 수월하게 광케이블을 대조할 수 있어서 광케이블 절단 작업 시 오절단을 사전에 예방할 수 있다.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1600-1604
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• 2017

A new Complex Image Method based on Genetic Algorithm (GA) is proposed to calculate the Green's functions of CPW (coplanar waveguide)-type microwave components and antennas. The closed-forms of the spectral-domain integrals are obtained by the GA, avoiding the conventional procedures of the tedious linear algebra and the sampling conditions sensitive to the complex-variable sampling paths adopted in the Prony's and GPOF methods. The proposed method is compared with the numerical Sommerfeld Integral, which results in good agreement.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.257-258
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• 2007

In real-time video communications, the large fluctuation of bits generated from contiguous frames may lead to the buffer oveflow and the delay of transmitting video data. This paper proposes a method that the bits generated from each frame may be in the range of specified fluctuation. The method uses a scene change detector and ignores the time information of detected frames. The experimental results indicate that our scheme achieves average PSNR gain of 2.0dB over TMN8.