• 한국통신학회논문지
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• 제31권7C호
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• pp.691-699
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• 2006

VoIP(Voice over Internet Pratocol)와 같은 IP 네트워크망에서는 패킷 지연, 지터, 패킷 손실 등의 이유로 QoS(Quality of Service)를 보장받지 못하기 때문에, 패킷 손실을 은닉하는 방법에 대한 연구는 필수적이다. IP망에서 사용되는 대부분의 저전송률 음성부호화기는 자체적으로 패킷 손실 은닉(PLC: Packet Loss Concealment) 알고리즘을 사용하고 있지만, 예측 기법에 기반한 양자화 특성상 패킷 손실 이후에도 에러가 전파되는 문제가 있다. 또한, 손실된 패킷의 음성신호 특성을 고려하지 않고 과거 파라미터값을 반복시키는 기존 PLC 방법은 그 구현은 쉽지만 천이구간에서의 합성신호의 음질이 심각히 저하된다. 본 논문에서는 패킷 손실 환경에서 랩신호 특성에 따른 에러전파 영향을 정량적으로 분석하고 그 결과를 토대로 보간법 기반의 새로운 PLC 알고리즘을 제안한다. 제안한 알고리즘은 파라미터별로 음성신호의 특성을 고려해 선택적으로 보간법을 적용하고, 예측 필터의 메모리를 효과적으로 갱신한다. 성능평가 결과, 제안한 알고리즘은 VoIP에서 널리 사용되는 G.729 의 기존 PLC 알고리즘에 비해 다양한 FER 환경에서 성능이 향상되었다.

• 한국통신학회논문지
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• 제36권2A호
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• pp.172-178
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• 2011

본 논문은 차세대 유럽형 디지털 지상파 시스템으로 알려진 DVB-T2 시스템의 BICM(Bit Interleaved Coded and Modualtion) 모듈의 FER(frame error rate) 및 BER (bit error rate)성능을 전산 실험을 통해 분석하였다. AWGN 채널, flat 페이딩 Rayleigh 채널 및 15% erasure 채널에서 ETSI EN 302 555 표준에 따라 제작된 full 시뮬레이터를 통해 실험을 하였으며, 수신 모듈은 디매퍼가 LDPC 채널 디코더로부터 전달되는 apriori 정보를 이용하여 LLR(log likelihood ratio) 값을 계산하는 iterative demapping decoder (IDD) 기술을 적용하였다. 또한 DVB-T2 시스템에서 선택적으로 사용할 수 있는 성상회전(rotated constellation) 기술의 성능도 비교하였다. 실험 결과 flat 페이딩 Rayleigh 채널에서 성상회전을 사용할 경우, 사용하지 않은 시스템에 비해서 $FER=10^{-4}$에서 약 0.5dB 정도의 Eb/No[dB]의 이득을 얻을 수 있으며, 성상회전과 IDD를 동시에 적용할 경우, 1.2 dB 정도의 Eb/No[dB]의 이득을 얻을 수 있음을 확인할 수 있었다. 또 15% erasure가 있는 채널에서는 성상회전을 적용할 때 $BER=10^{-4}$ 지점에서 대략 5dB 정도의 Eb/No[dB]의 이득을 얻을 수 있으며, IDD를 적용할 경우 추가적인 3dB의 이득이 있음을 확인할 수 있었다.

• 한방비만학회지
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• 제15권1호
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• pp.9-23
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• 2015

Objectives: This study was investigated the improvement effects of Pakistani Ephedra herba-containing Gangji-hwan-1, 2, 3 (Di-fatty; DF-1, 2, 3), Chinese Ephedra herba-containing Gangjihwan-4 (DF-4) and combination of DF-1 and Gamisoche-hwan (GSH) on obesity in a high fat diet-fed obese mouse model. Methods: Eight-week-old C57BL/6N mice were divided into seven groups: a normal lean group given a standard diet, an obese control group given a high fat diet, and DF-1, 2, 3, 4, and DF-1+GSH groups given a high fat diet with DF-1, 2, 3, 4 (40, 80, 160, 80 mg/kg), and DF-1+ GSH (80 mg/kg), respectively. After 8 weeks of treatment, body weight gain, feeding efficiency ratio (FER), blood lipid markers, liver histology, and fat weight and histology were examined. Results: Body weight gain was significantly decreased in DF and DF-1+GSH groups compared with control. The extent of decreases was eminent in DF-1+GSH group. FER and circulating concentration of leptin were decreased in DF and DF-1+GSH groups compared with control. Circulating concentrations of triglyceride, glucose and insulin were decreased in DF and DF-1+GSH groups compared with control. The size of adipocytes were decreased by DF and DF-1+GSH groups compared with control, whereas the adipocyte number per unit area was increased by them, suggesting that DF and DF-1+GSH groups decreased the number of large adipocytes. Conclusions: In conclusion, these results suggest that DF and DF-1+GSH groups decrease FER, plasma leptin concentration, blood anti-obesity biomarkers and fat mass, improves body weight gain. In addition, these effects were more effective in DF-1+GSH combination group than in DF-1, 2, 3, 4 groups.

• 대한수학회지
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• 제39권2호
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• pp.319-330
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• 2002

The method of quasilinearization generates a monotone iteration scheme whose iterates converge quadratically to a unique solution of the problem at hand. In this paper, we apply the method to two families of three-point boundary value problems for second order ordinary differential equations: Linear boundary conditions and nonlinear boundary conditions are addressed independently. For linear boundary conditions, an appropriate Green\`s function is constructed. Fer nonlinear boundary conditions, we show that these nonlinearities can be addressed similarly to the nonlinearities in the differential equation.

• 한국컴퓨터정보학회논문지
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• 제6권2호
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• pp.34-40
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• 2001

본 논문에서는 Choudhary의 선분추적 방식의 교착상태 탐지 알고리즘을 소개한다. 그리고 이 알고리즘이 교착상태를 탐지하지 못하는 4가지 경우를 예를 들어 보여주고, 이 문제점을 해결한 새로운 알고리즘을 제시하고 있다.

• 한국잠사학회:학술대회논문집
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• 한국잠사학회 2003년도 International Symposium of Silkworm/Insect Biotechnology and Annual Meeting of Korea Society of Sericultural Science
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• pp.34-38
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• 2003

The silk fibre Produced by the larvae of the lepidopter of the Bombyx mori species is no doubt one of the most precious raw materials employed in manufacturing textile products. The present report, however, deals with silk not as a traditional textile fibre, but as a starting material fer biomedical applications. In recent years, the unique chemical and mechanical properties of silk have made this protein polymer highly attractive for innovative applications, which mainly focus on the development of devices for biomedical uses. (omitted)

• 한국초전도ㆍ저온공학회논문지
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• 제5권1호
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• pp.1-12
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• 2003

In this paper we present a brief description and summary results of each of our recent activities in three areas, all devoted to NMR and MRI superconducting magnet technologies: 1) development of a high-field LTS / HTS NMR magnet; 2) development of a novel digital flux injector for slightly resistive NMR magnets; and 3) a proposal fer a low-cost MRI magnet system based on $MgB_2$ composite and an innovative cryogenic design / operation concept.

• 한국통계학회:학술대회논문집
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• 한국통계학회 2000년도 추계학술발표회 논문집
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• pp.13-15
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• 2000

In this paper, we deal with the asymptotic properties of the regression quantile estimators in the nonlinear time series regression model. For the sinusodial model which frequently appears fer a time series analysis, we study the strong consistency and asymptotic normality of regression quantile ostinators.

• Korean Journal of Mathematics
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• 제20권2호
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• pp.185-191
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• 2012

Let D be an integral domain and SF(D) be the set of star operations of finite type on D. We show that if ${\mid}SF(D){\mid}$ < ${\infty}$, then every maximal ideal of D is a $t$-ideal. We give an example of integrally closed quasi-local domains D in which the maximal ideal is divisorial (so a $t$-ideal) but ${\mid}SF(D){\mid}={\infty}$. We also study the integrally closed domains D with ${\mid}SF(D){\mid}{\leq}2$.

• 자원리싸이클링
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• 제11권5호
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• pp.11-15
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• 2002

China is a large country fer the production of magnetic materials because of its cheap price and abundant raw materials. The total yield of ferrite occupies about 20% fraction in the market of the world. In this report, the characteristics and the yield of the ferrite magnet produced in China were displayed. Also the distribution of manufacturers and research institutes and the Chinas 10th five-year-plan on the magnetic materials were reviewed.