• ALGAE
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• 제31권4호
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• pp.303-315
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• 2016

Compsopogon specimens collected in China were examined based on morphology and DNA sequences. Five molecular markers from different genome compartments including rbcL, COI, 18S rDNA, psbA, and UPA were identified and used to construct a phylogenetic relationship. Phylogenetic analyses indicated that two different morphological types from China clustered into an independent clade with Compsopogon specimens when compared to other global samples. The Compsopogon clade exhibited robust support values, revealing the affiliation of the samples to Compsopogon caeruleus. Although the samples were distributed in a close geographical area, unexpected sequence divergences between the Chinese samples implied that they were introduced by different dispersal events and from varied origins. It was speculated that Compsopogon originated in North America, a portion of the Laurentia landmass situated in the Rodinia supercontinent at approximately 573.89-1,701.50 million years ago during the Proterozoic era.Although Compsopogonhad evolved for a rather long time, genetic conservation had limited its variability and rate of evolution, resulting in the current monospecific global distribution. Additional global specimens and sequence information were required to increase our understanding of the evolutionary history of this ancient red algal lineage.

• International Journal of Aeronautical and Space Sciences
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• 제3권1호
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• pp.74-85
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• 2002

The numerical experiment has been conducted to investigate the unsteady shock wave reflecting phenomena. The cell-vertex finite-volume, Roe's upwind flux difference splitting method with unstructured grid is implemented to solve unsteady Euler equations. The $4^{th}$-order Runge-Kutta method is applied for time integration. A linear reconstruction of the flux vector using the least-square method is applied to obtain the $2^{nd}$-order accuracy for the spatial derivatives. For a better resolution of the shock wave and slipline, the dynamic grid adaptation technique is adopted. The new concept of grid adaptation technique, which is much simpler than that of conventional techniques, is introduced for the current study. Three error indicators (divergence and curl of velocity, and gradient of density) are used for the grid adaptation procedure. Considering the quality of the solution and the numerical efficiency, the grid adaptation procedure was updated up to $2^{nd}$ level at every 20 time steps. For the convenience of comparison with other experimental and analytical results, the case of interaction between the straight incoming shock wave and a sharp wedge is simulated for various flow conditions. The numerical results show good agreement with other experimental and analytical results, in the shock wave reflecting structure, slipline, and the trajectory of the triple points. Some critical cases show disagreement with the analytical results, but these cases also have been proven to show hysteresis phenomena.

• 한국정보기술학회논문지
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• 제16권11호
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• pp.97-103
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• 2018

본 논문에서는 시변 최적 FIR 필터를 이용한 전력 신호의 고조파 검출 방법을 제안한다. 잡음이 고려된 전력 신호에 대해 고조파의 진폭과 위상각의 변화량이 확률적 정보로 고려된 시변 상태 방정식 모델에 대해 시변 최적 FIR 필터를 설계하여 고조파 성분을 검출한다. 제안한 검출 방법에 사용된 시변 FIR 필터는 유한 구간의 정보만을 사용하고 어떠한 초기 조건도 사용하지 않도록 설계되어 칼만 필터 기반의 검출 방법의 오차 누적에 따른 검출 성능 저하나 발산 문제를 해결할 수 있다. 또한 FIR 구조의 필터 사용을 통해 칼만 필터 대비 불확실성에 대해 보다 강인한 검출이 가능하다. 시변 최적 FIR 필터의 사용을 통해 시불변 최적 FIR 필터 기반 고조파 검출 방법 대비 보다 일반적인 해를 제공한다. 제안하는 검출 방법의 우수성을 검증하기 위해 시변 칼만 필터 및 적응 칼만 필터 기반 고조파 검출 방법과의 비교 시뮬레이션을 수행한다.

• 지구물리와물리탐사
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• 제24권4호
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• pp.164-170
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• 2021

주파수 및 시간영역 유도분극 탐사는 지하 매질의 분광 정보를 포함하고 있다. 분광 특성의 분석은 주로 주파수영역 유도분극 탐사에서 연구되어 왔으나, 근래에 시간영역 유도분극에서도 연구가 활발하게 이루어지고 있다. 이 연구에서는 반무한 균질 공간을 가정하고 측정된 2차 전위 및 전기비저항으로부터 Cole-Cole 변수를 추정하는 역산법을 개발하였다. 충전성, 완화시간 및 주파수 승수로 구성되는 Cole-Cole 변수들은 비독립적이기 때문에 통상적인 비선형 역산을 적용할 경우 느린 수렴속도, 적정 초기 모델 설정의 어려움, 지역 극소점, 발산 위험 등의 다양한 문제점이 발생한다. 이 연구에서는 격자 탐색법을 도입하여 참 모델에 근접한 초기 모델을 설정하는 효과적인 역산법을 개발하였다. 마지막으로 다양한 역산 실험을 통하여 개발된 역산법의 타당성을 검증하였다.

• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2690-2697
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• 2024

With advancements in machine learning technologies, artificial neural networks (ANNs) are being widely used to improve the performance of gamma-ray spectroscopy based on NaI(Tl) scintillation detectors. Typically, the performance of ANNs is evaluated using test datasets composed of actual spectra. However, the generation of such test datasets encompassing a wide range of actual spectra representing various scenarios often proves inefficient and time-consuming. Thus, instead of measuring actual spectra, we generated virtual spectra with diverse spectral features by sampling from categorical distribution functions derived from the base spectra of six radioactive isotopes: ⁵⁴Mn, ⁵⁷Co, ⁶⁰Co, ¹³⁴Cs, ¹³⁷Cs, and ²⁴¹Am. For practical applications, we determined the optimum counting time (OCT) as the point at which the change in the Kullback-Leibler divergence (ΔKLDV) values between the synthetic spectra used for training the ANN and the virtual spectra approaches zero. The accuracies of the actual spectra were significantly improved when measured up to their respective OCTs. The outcomes demonstrated that the proposed method can effectively determine the OCTs for gamma-ray spectroscopy based on ANNs without the need to measure actual spectra.

• 한국컴퓨터정보학회논문지
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• 제20권4호
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• pp.25-32
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• 2015

유전자 알고리즘은 초기 해 집합을 대상으로 해 집합의 평가와 유전자 연산자의 적용, 자연 선택 등의 과정을 반복하여 최적 해를 찾는 탐색 알고리즘이다. 유전자 알고리즘을 설계할 때 사용한 선택 전략, 세대교체 방법, 유전자 연산자 등은 유전자 알고리즘의 탐색 효율성에 영향을 준다. 본 논문에서는 시간 제약이 있는 상황에서의 로봇 경로 탐색을 위해 기존의 유전자 알고리즘보다 빠르게 수렴하는 유전자 알고리즘을 제안한다. 로봇 경로 탐색 시 긴급한 상황에서 유전자 알고리즘은 연산을 위한 충분한 시간을 확보하지 못 하게 되고, 이는 최종적으로 찾아낸 경로의 질을 떨어뜨린다. 제안하는 알고리즘은 빠른 수렴을 위한 선택 전략, 세대교체 방법을 사용하였으며, 유전자 연산자로는 전통적인 교차, 돌연변이 외에 경로의 길이를 줄이기 위한 단축 연산자를 추가로 사용하였다. 이를 통해 제안하는 알고리즘은 적은 세대 수에도 빠르게 짧은 경로를 찾아낸다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2641-2647
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• 2003

Conventional DLLs estimate the delay times of satellite signals individually and feed back these measurements to the VCO independently. But VDLL estimates delay times and user position directly and then estimate the feedback term for VCO using the estimated position changes. In this process, input measurements are treated as vectors and these vectors are used for navigation. First advantage of VDLL is that noise is reduced in all of the tracking channels making them less likely to enter the nonlinear region and fall below threshold. Second is that VDLL can operate successfully when the conventional independent parallel DLL approach fails completely. It means that VDLL receiver can get enough total signal power to track successfully to obtain accurate position estimates under the same conditions where the signal strength from each individual satellite is so low or week that none of the individual scalar DLL can remain in lock when operating independently. To operate VDLL successfully, it needs to know the initial user dynamics and position and prevents total system from the divergence. The suggested integration method is to use the inertial navigation system to provide initial dynamics for VDLL and to maintain total system stable. We designed the GPS/INS integrated navigation system. This new type of integrated system contained the vector pseudorange format generation block, VDLL signal processing block, position estimation block and the conversion block from position change to delay time feedback term aided by INS.

• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1418-1422
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• 2006

In this work the construction of a novel poly(vinyl chloride) membrane sensor based on 2,2'-dianiline disulfide (DADS) as a neutral carrier, o-nitrophenyloctyl ether (NPOE) as a plasticizer and sodium tetraphenyl borate (NaTPB) as an anionic site with unique selectivity towards Tm(III) ions is reported. The electrode has a linear dynamic range between $1.0\;{\times}\;10^{-6}$ and $1.0\;{\times}\;10^{-2}$ M, with a nice Nernstian slope of 19.5 ${\pm}$ 0.3 mV per decade and a detection limit of $4.0\;{\times}\;10^{-7}$ M at the pH range of 4.8-8.5. It has a very fast response time (<15 s) in the whole concentration range, and can be used for at least 4 weeks without any considerable divergence in the electrode potentials. The proposed sensor revealed comparatively good selectivity with respect to most common metal ions, and especially lanthanide ions. It was used as an indicator electrode in the potentiometric titration of Tm(III) ions with EDTA and in direct determination of concentration of Tm(III) ions in binary mixtures. It was also applied in determination of fluoride ions in mouth wash preparations.

• Asian-Australasian Journal of Animal Sciences
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• 제19권11호
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• pp.1556-1560
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• 2006

Six breeds of riverine buffalo viz. Murrah, Mehsana, Jaffrabadi, Nagpuri, Nili-Ravi and Bhadawari were characterized using FAO-recommended cattle specific microsatellite markers. Among the total of twenty microsatellite markers screened to explore genomic variability of six buffalo breeds, only ten were polymorphic in nature. Four out of ten polymorphic microsatellite loci were rated as informative. The numbers of alleles detected ranged from 2 to 7, with a mean of $5.5{\pm}0.07$ per microsatellite marker. The most polymorphic marker was BM1818 with a total of 7 alleles present at this locus. One breed specific marker was found in each of Mehsana (BM1818) and Bhadawari (ILSTS030) and four were found in Jaffarabadi (BM1818, ILSTS030, ILSTS054 and ILSTS011). Genetic distance (Ds) between the Mehsana and Bhadawari breed was the maximum (0.29), followed by Murrah and Mehsana (0.27), and Nili-Ravi and Bhadawari (0.26). The lowest Ds was found between the Jaffrabadi and Nagpuri breeds which was only 0.05. The highest divergence time of 1318 years was established between Mehsana and Bhadawari breeds whereas it was found to be lowest (272 years) between the Jaffrabadi and Nagpuri breeds.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.33-38
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• 2001

Bifurcation of unstable symmetric flow patterns to stable asymmetric ones in laminar sudden-expansion flow has been numerically investigated. Computations were carried out for an expansion ratio of 3 and over a range of the flow Reynolds numbers by using numerical methods of second-order time accuracy and a fractional-step method that guarantees divergence-free flowfields at all times. The critical Reynolds number above which bifurcation of pitchfork type to asymmetric flow pattern takes place is lower in a flow with a higher expansion ratio, in agreement with the previously reported results. The bifurcation diagrams show that the bifurcation takes place at a Reynolds number, $Re_c = 86.3$, higher than the value that has been reported. The lower critical Reynolds number may be due to deficiencies in their computations which employed SIMPLE-type relaxation methods rather than the initial-value approach of the present study. Characteristics of the flow development during the transition to asymmetric stable flow have been investigated by using spectral analysis of the velocity signals obtained by the simulations.