• ETRI Journal
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• 제26권5호
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• pp.432-436
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• 2004

In this paper, we propose the modified uniformly most powerful (UMP) belief-propagation (BP)-based decoding algorithm which utilizes multiplicative and additive factors to diminish the errors introduced by the approximation of the soft values given by a previously proposed UMP BP-based algorithm. This modified UMP BP-based algorithm shows better performance than that of the normalized UMP BP-based algorithm, i.e., it has an error performance closer to BP than that of the normalized UMP BP-based algorithm on the additive white Gaussian noise channel for low density parity check codes. Also, this algorithm has the same complexity in its implementation as the normalized UMP BP-based algorithm.

• 천문학회보
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• 제44권1호
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• pp.68.2-68.2
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• 2019

Chemical abundance ratios of ultra metal-poor (UMP; [Fe/H] < -4.0) stars can provide important constraints on the early chemical enrichment of the Milky Way (MW), associated with the nucleosynthesis processes that occurred during the evolution of their progenitors, which are presumably the first generation of stars. Despite their importance, only about thirty UMP stars have been discovered thus far. In an effort to identify such stars additionally, we selected UMP candidates from low-resolution (R ~ 2000) spectra from the Sloan Digital Sky Survey and Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST), and obtained with Gemini/GRACES high-resolution (R ~ 40,000) spectra of 15 UMP candidates. In this study, we present the results of the chemical abundance analysis of the UMP candidates. Furthermore, we compare the abundance patterns of our UMP stars with those of various metal-poor stars from literature to understand the early chemical evolution of the MW.

• 대한임베디드공학회논문지
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• 제4권4호
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• pp.195-200
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• 2009

As 4G mobile communication systems require high transmission rates with reliability, the need for efficient error correcting code is increasing. In this paper, a novel LDPC (Low Density Parity Check) decoder is introduced. The LDPC code is one of the most popular error correcting codes. In order to improve performance of the LDPC decoder, we use SNR (Signal-to-Noise Ratio) estimation results to adjust coefficients of modified UMP-BP (Uniformly Most Probable Belief Propagation) algorithm which is one of widely-used LDPC decoding algorithms. An advantage of Modified UMP-BP is that it is amenable to implement in hardware. We generate the optimal values by simulation for various SNRs and coefficients, and the values are stored in a look-up table. The proposed decoder decides coefficients of the modified UMP-BP based on SNR information. The simulation results show that the BER (Bit Error Rate) performance of the proposed LDPC decoder is better than an LDPC decoder using a conventional modified UMP-BP.

• 한국음향학회지
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• 제26권1호
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• pp.16-24
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• 2007

음성검출기는 이동 통신이나 음성신호처리 등에 매우 중요한 기법으로 사용된다. 일반적인 음성검출방식은 통계적인 모델을 기반으로 하여 likelihood ratio test (LRT)를 하게 된다. 그리고 이 값을 임계값과 비교하여 음성인지 아닌지 판단하게 된다. 본 논문에서는 가우시안 (Gaussian) 분포를 기반으로 하고 uniformly most powerful (UMP) 테스트를 이용하여 새로운 음성검출기법을 제안한다. 새로운 음성검출기법의 결정규칙은 기존 LRT에 기반하여 UMP 테스트를 통해 식을 유도하였다. UMP 테스트를 이용하면, 입력음성에 대한 절대값의 확률 분포를 Rayleigh 분포 형태로 얻을 수 있으며, 이 분포에 따라 최종적으로 음성검출을 하게 된다. 이 새로운 방식의 음성검출기는 기존의 방식에서 필요한 a priori signal-to-noise ratio (SNR) 값을 구하지 않고도 음성 유무를 판단할 수 있다는 장점이 있다. 실제로 다양한 음성검출에 대한 성능 평가결과, 제안된 기법이 기존 방식에 비해 우수한 성능을 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제15권3호
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• pp.573-578
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• 2005

Pyrimidine nucleotide N-ribosidase (pyrimidine 5'-nucleotide phosphoribo(deoxyribo)hydrolase/pyrimidine 5'-nucleotide nucleosidase, EC 3.2.2.10) catalyzes the breakdown of pyrimidine 5'-nucleotide into pyrimidine base and ribose(deoxyribo)-5-phosphate. However, detailed characteristics of the enzyme have not yet been reported. The enzyme was purified to homogeneity 327.9-fold with an overall yield of $6.1\%$ from Pseudomonas oleovorans ATCC 8062. The enzyme catalyzed cytidine monophosphate (CMP) and uridine monophosphate (UMP), but not adenosine monophosphate (AMP) and guanosine monophosphate (GMP). The enzyme optimally metabolized CMP at pH 6.0 and UMP at around 8.5, and the optimum temperature for the overall enzyme reaction was found to be $37^{\circ}C$. The $K_m$ values of the enzyme for CMP (at pH 6.0) and UMP (at pH 8.5) were 1.6 mM and 1.1 mM, respectively. AMP, deoxyCMP, and deoxyUMP were very effective inhibitors of the reaction. Double-reciprocal plots obtained in the absence and in the presence of AMP revealed that this inhibitory effect was of the mixed competitive type with respect to the breakdown of CMP and of the noncompetitive type with respect to the breakdown of UMP. In the presence of AMP, the enzyme followed sigmoid kinetics with respect to each substrate.

• Communications for Statistical Applications and Methods
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• 제6권1호
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• pp.293-303
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• 1999

When test outcomes of units are dichotomous and he infection rate is small group testing is more efficient that noe-to-one testing in estimating the true p and classifying units as infected or not. In this paper two-sided hypothesis testing and confidence intervals are derived based on the UMP(uniformly most powerful) unbiased test. The UMP unbiased approach is compared with Thompson's and Bhattacharyya et al.'s approaches by computing the length of confidence intervals and capture probabilities and shown to have a number of desirable properties. Unequal allocation one of advantages of the proposed approach is also mentioned.

• 천문학회보
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• 제42권2호
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• pp.87.1-87.1
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• 2017

We present preliminary results of elemental abundances of six ultra-metal poor (UMP; [Fe/H] < -4.0) stars derived from high-resolution spectra obtained by Gemini/GRACES. The UMP candidates were selected for the high-resolution follow-up from the low-resolution spectra of Sloan Digital Sky Survey (SDSS). We investigate possible progenitors of the UMP objects by comparing the measured abundance patterns with yields that various supernova models predict. Our results can provide stringent constraints on the mass range of the first generation of stars, which are the progenitors of the UMP objects.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1321-1327
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• 2006

This paper presents the calculation of unbalanced magnetic pull (UMP) that causes rotor misalignment in induction motor. The excessive noise and vibration will be occurred by means of rotor misalignment. Angular misalignment of rotor will produce air-gap permeance wave which is function of axial and circumferential coordinate. In this paper, the UMP is calculated using permeance and magneto motive force (MMF) in the case of static and dynamic misalignment. Based on the percentage of misalignment, the result shows that the UMP and magnetic pressure are increased according to the increasing of misalignment. The UMP is occurred not only in It frequency component but also the others.

• 천문학회보
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• 제44권2호
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• pp.50.1-50.1
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• 2019

Ultra Metal-Poor (UMP; [Fe/H] < -4.0) stars are thought to be true second generation of stars. Thus, the chemistry and kinematics of these stars serve as powerful tools to understand the early evolution of the Milky Way (MW). However, only about 40 of these stars have been discovered thus far. To increase the number of these stars, we selected UMP candidates from low-resolution spectra (R ~ 2000) of the Sloan Digital Sky Survey (SDSS) and Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST), and performed high-resolution (R ~ 40,000) spectroscopic follow-ups with Gemini/GARACES. In this study, we present chemical and kinematic properties of the observed UMP candidates, and infer the nature of their progenitors to trace the chemical enrichment history of the MW.

• 한국통신학회:학술대회논문집
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• 한국통신학회 2004년도 추계종합학술대회 논문 초록집
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• pp.134-134
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• 2004