• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.109-113
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• 2004

In case while modulation index (M) is more than 0.7, the spectrum of motor voltage and current of a conventional two-phase SRP scheme are not reduced considerably. To solve the problems of a conventional two-phase SRP, this paper proposes a two-phase SRP(DZSRP) with double zero vector mode which zero vector is selected as V(111) in case of M $\geq$ 0.7, and zero vector is selected as V(000) if M < 0.7. For the validity of the proposed method, a 16 bit micro-controller C167 was used and the experiments were conducted with the 1.5kw induction motor under load condition. And the experimental results show that the switching noise spectrum for all the M are spread to a wide band area. Also the switching noise and conducted noise are discussed.

• ETRI Journal
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• 제37권4호
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• pp.647-656
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• 2015

This paper proposes a single-RF MIMO receiver that adopts a beam-switching antenna (BSA) instead of a conventional array antenna. The beauty of the proposed single-RF MIMO receiver with BSA is that it can be deployed in a very small physical space while achieving a full spatial multiplexing gain. Our analysis has revealed that the use of a BSA inevitably results in the spectrum spreading effect at the RF output, which in turn causes an SNR decrease and adjacent channel interference (ACI). Two novel receiver techniques are proposed to mitigate the issues of redundant sub-band suppression and ACI avoidance. Numerical analysis results verify the performance improvement from the proposed receiver techniques.

• 한국통신학회논문지
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• 제22권4호
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• pp.761-770
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• 1997

Narrowband signals can be treated like a single tone interference at the receiver which demodulates wideband signals spectrum overlaid at the same frequency band. In this paper, the single tone interference is effectively suppressed by the use of a multicarrier DPSK direct-sequence(DS) spread spectrum(SS) with maximal-ratio(MR) combining instead of notch filter, which is hard to implement. A noncoherent DPSK system is considered because it is more realizable and does not require any complicate phase tracking, compared with a single carrier system subject to a constraint system bandwidth, and their performance comparisons are validated through simulation. We also propose a suboptimal-ratio(SR) combining which yields uniform and tight low bound on the performance of the MR combining, and then system parameters re optimized by theoretically evaluating the low bound, since an exact analysis appears intractable.

• 대한전자공학회논문지
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• 제23권4호
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• pp.529-534
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• 1986

A holographic iverse filter has been used for optical image deblurring by modeling the PSF(point spread function)of blurred system. This paper presents the optical image restoration of an accidentally blurred photograph by using a simgle inverse filter which is obtained from a blurrec PSF by analyzing the Fourier spectrum of the supposely defocused photograph itself. The filter, a positive transparency having gamma of 2, has amplitude and phase informations simulatneously.

• Journal of Animal Science and Technology
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• 제57권1호
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• pp.2.1-2.5
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• 2015

Among the main intimidation to the sheep and goat population, PPR outbreaks are causing huge losses especially in endemic areas. During recent times, six outbreaks of PPR were confirmed at semi-organized goat farms/herds in various regions of Punjab province and Islamabad capital territory (ICT), Pakistan. The disease started after introduction of new animals at these farms with no history of previous PPR vaccination. The clinical signs appeared affecting respiratory and enteric systems and spread quickly. Disease caused mortality of 10-20% and morbidity of 20-40% within a time period of four weeks. Morbidity and mortality rates were 30.38% (86/283) and 15.55% (44/283), respectively. Three treatment regimes were executed to demonstrate the role of vaccination during outbreak at these farms. First was to use only the broad spectrum antibiotics (Penicillin & Streptomycin and/or Trimethoprim and Sulfadiazine) at two farms (Texilla and Attock). Second treatment regime was to use the same broad spectrum antibiotic along with extensive fluid therapy (Farms at ICT-1 and ICT-2). The third regime was to use of broad spectrum antibiotic plus fluid therapy along with vaccinating the herd against PPR during first week of outbreak (ICT-3 and ICT-4). The third scheme of treatment gave the better results as there was no mortality in third week post-outbreak. Therefore, it is suggested to give proper importance to PPR vaccination along with conventional symptomatic treatment when dealing the PPR outbreaks in endemic disease conditions.

• 한국정보통신학회논문지
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• 제16권8호
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• pp.1686-1692
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• 2012

확산수열(spreading sequence)은 다중 반송파 대역확산(multi-carrier spectrum) 통신시스템과 CDMA와 같은 무선통신에서 중요한 역할을 한다. 이러한 통신 시스템에서 낮은 상호상관관계를 갖는 확산수열은 다중접속 충돌을 최소화하고, 시스템의 보안수준을 가능한 높일 수 있다. 수열을 설계하는 데 있어 상호상관관계를 분석한는 것을 반드시 필요한 절차이다. 상호상관관계를 분석하기 위해서는 많은 계산 시간이 요구된다. 본 논문에서는 비선형 이진수열의 상호상관관계를 실제적으로 계산하는 과정에서 부분체를 이용하여 효과적으로 구하는 방법을 제안한다.

• Journal of Communications and Networks
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• 제5권4호
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• pp.290-302
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• 2003

Ultra wide band (UWB) radio has recently attracted increased attention due to its expected unlicensed operation, and potential to provide very high data rates at relatively short ranges. In this article we briefly describe some main candidate multiple access and modulation schemes for UWB communications, followed with their power spectral density calculation and properties. We also present some illustrative capacity results, and provide a discussion of the impact of network topology on multiple access capacity.

• 전자통신동향분석
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• 제12권6호통권48호
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• pp.1-14
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• 1997

본 글에서는 일반적인 무선 LAN 기술과 사용 주파수 대역에 대해서 간략히 기술하였고, 특히, 스펙트럼 확산방식을 사용하는 무선 LAN의 규제항목을 DS방식과 FH방식으로 구분하여 IEEE 802.11 표준(안)을 중심으로 두 방식을 비교하였다. 그리고 무선 LAN과 관련된 제외국 표준(안) 및 관련 법규(ETS 300 328 표준(안), IEEE 802.11 표준(안), FCC Part 15.247, 일본 RCR-33A 등)를 국내 무선 LAN 기술기준과 비교하여 새로운 기술기준 항목을 도출하였다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1993년도 학술논문발표회 논문집 제12권 1호
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• pp.276-279
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• 1993

이 논문에서는 페이딩이 있는 채널에서 충격성 잡음이 있을 때 부호 상관 수신기를 쓰는 DS/SSMA 시스템의 성능을 분석하였다. 좀 더 자세히 말하면, 확산 수열이 짧을 때에는 직접 계산으로, 확산 수열이 길 때에는 근사식으로 부호 상관 수신기를 쓰는 DS/SSMA 시스템의 비트 오류 발생 확률을 얻었다. 이를 통해 사용자가 한 사람일때에는 이 시스템의 성능이 신호대 잡음비의 변화에 크게 영향을 받지 않는다는 것을 보였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅲ
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• pp.1487-1490
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• 2003

This paper shows the watermarking system that inserts copyright holder's logo in music file. In other words, a sound file is able to have an image information like a logo or letters. The watermarking system converts a sound file into an image file using spectrogram. In the spectrogram domain, a logo is inserted using spread spectrum. The proposed technique shows that the verification of copyright is better than the method using PN-Sequence.