• 한국전산유체공학회지
• /
• 제16권4호
• /
• pp.7-13
• /
• 2011

A comparative analysis of thermal models in the lattice Boltzmann method(LBM) for the simulation of laminar natural convection in a square cavity is presented. A HYBRID method, in which the thermal equation is solved by the Navier-Stokes equation method while the mass and momentum conservation are resolved by the lattice Boltzmann method, is introduced and its merits are explained. All the governing equations are discretized on a cell-centered, non-uniform grid using the finite-volume method. The convection terms are treated by a second-order central-difference scheme with a deferred correction method to ensure stability of the solutions. The HYBRID method and the double-population method are applied to the simulation of natural convection in a square cavity and the predicted results are compared with the benchmark solutions given in the literatures. The predicted results are also compared with those by the conventional Navier-Stokes equation method. In general, the present HYBRID method is as accurate as the Navier-Stokes equation method and the double-population method. The HYBRID method shows better convergence and stability than the double-population method. These observations indicate that this HYBRID method is an efficient and economic method for the simulation of incompressible fluid flow and heat transfer problem with the LBM.

• 생명과학회지
• /
• 제7권4호
• /
• pp.347-354
• /
• 1997

Some attempts were made to investigate the gentic characteristics of the brown planthopper(BPH), Nilaparvata lugens Sta${\aa}$l, biotypes. In terms of egg and nymphal periods, egg hatcgability, emergence ratio, and population change of BPH and plant damage of rice cultivars by the infestation of BPH biotypes and their hybrid progenies in field conditions. The egg and nymphal periods of the three of BPH biotypes and their hybrid progenies on Dongjinbyeo with no resistance gene were shorter than on rice cultivars with resistance gene. But the periods of biotype-2(♀) X 2(♂) (E) on Samgangbyeo with Bph-1 gene and biotype-3(♀) X 3(♂)(I) on Mirying 63 with bph-2 gene were as short as on Dongjinbyeo. The egg hatchability and emergence ratio of the three Bph biotypes and their hybrid progenies on Dongjinbyeo were higher than on the other rice cultivars, and those of E on Samgangbyeo and I on Miryang 63 were as high as on Dongjinbyeo. In rice paddy field, biotype-1(♀) X 1(♂)(A)$\sim$I infested on Dongjinbyeo, E onSamgangbyeo, and I on Miryang 63 were increased their population densities remarkably in next generation. Dongjinbyeo infested by A$\sim$I, and Myryang 63 infested by I were hopperburned at 60 days after infestation and had a damage rating of 0.9. But Samgangbyeo infested by E was no hopperburn(damage rating: 7.3) though it showed high BPH population at 60 days after infestation.

• 한국약용작물학회지
• /
• 제14권2호
• /
• pp.107-112
• /
• 2006

Two Atractylodes species, A. japonica Koidz. ex Kitam. (AJ) and A. macrocephala Koidz (AM) were used in this study. AJ population had higher amounts of Sesquiterpenoids and stronger tolerance to root rot but less vigor of root growth than AM population. Two populations (AJ and AM) were crossed to make interspecific hybrid population. A total of 98 lines propagated clonally were selected from a cross of AJ and AM, and evaluated for contents of sesquiterpenoids, atractylon (ATLN) and atractylenolide III (AT3) using high performance liquid chromatography (HPLC), and growth characters such as plant height, stem number and root weight. HPLC profiles of the hybrids were compared with those of parent plants, and it demonstrated the production of introgression hybrid by crossing between AJ and AM. Of 98 clonal lines,10 lines were selected by 10% level based on the growth vigor and tolerance to root rot, and AJM2102-51 line showed the heaviest root weight (117.1 g/plant) among them. A total of 98 hybrid lines contained on average $0.16\;{\pm}\;0.10\;mg/g$ of $AT3,\;2.00\;{\pm}\;1.37\;mg/g$ of ATLN, and $2.16\;{\pm}\;1.40\;mg/g$ of total sesquiterpenoids, showing high coefficients of variation (above 65%). Ten lines having high contents of sesquiterpenoids were selected, and AJM2101-15 had the highest amount (9.83 mg/g) of ATLN, and showed 40.8 g/plant of root weight similar to mean value (39.9 g/plant) of hybrid lines. The result showed that the introgression of both characters of vigorous growth from AM and high sesquiterpenoids content from AJ could be possible to make new hybrid lines by crossing between AJ and AM.

• Asian-Australasian Journal of Animal Sciences
• /
• 제18권5호
• /
• pp.613-619
• /
• 2005

Indigenous Yakutian cattle' adaptation to the hardest subarctic conditions makes them a valuable genetic resource for cattle breeding in the Siberian area. Since early last century, crossbreeding between native Yakutian cattle and imported Simmental and Kholmogory breeds has been widely adopted. In this study, variations at 22 polymorphic microsatellite loci in 5 populations of Yakutian, Kholmogory, Simmental, Yakutian-Kholmogory and Yakutian-Simmental cattle were analysed to estimate the genetic contribution of Yakutian cattle to the two hybrid populations. Three statistical approaches were used: the weighted least-squares (WLS) method which considers all allele frequencies; a recently developed implementation of a Markov chain Monte Carlo (MCMC) method called likelihood-based estimation of admixture (LEA); and a model-based Bayesian admixture analysis method (STRUCTURE). At population-level admixture analyses, the estimate based on the LEA was consistent with that obtained by the WLS method. Both methods showed that the genetic contribution of the indigenous Yakutian cattle in Yakutian-Kholmogory was small (9.6% by the LEA and 14.2% by the WLS method). In the Yakutian-Simmental population, the genetic contribution of the indigenous Yakutian cattle was considerably higher (62.8% by the LEA and 56.9% by the WLS method). Individual-level admixture analyses using STRUCTURE proved to be more informative than the multidimensional scaling analysis (MDSA) based on individual-based genetic distances. Of the 9 Yakutian-Simmental animals studied, 8 showed admixed origin, whereas of the 14 studied Yakutian-Kholmogory animals only 2 showed Yakutian ancestry (>5%). The mean posterior distributions of individual admixture coefficient (q) varied greatly among the samples in both hybrid populations. This study revealed a minor existing contribution of the Yakutian cattle in the Yakutian-Kholmogory hybrid population, but in the Yakutian-Simmental hybrid population, a major genetic contribution of the Yakutian cattle was seen. The results reflect the different crossbreeding patterns used in the development of the two hybrid populations. Additionally, molecular evidence for differences among individual admixture proportions was seen in both hybrid populations, resulting from the stochastic process in crossing over generations.

• Advances in Energy Research
• /
• 제6권2호
• /
• pp.145-160
• /
• 2019

The world population reaches to about 7.7 billion in 2018 from 6.2 billion in 2000. This much growth in population results in increased energy demand and increased food supply. As the conventional energy sources are limited. These may deplete soon if consumed at this rate. So, the world is switching towards the utilization of non-conventional sources of energy. Energy from sun is the best method as it can not only solve the energy issue but also helps in meeting food demand by conserving it. Greenhouses are made for the purpose of food conservation. Various types of solar dryers are developed by researchers till now and still the effort is being putted to make them more efficient. Hybrid greenhouse is also effort toward utilization of solar energy in more efficient way. The paper presents the heat and mass transfer analysis of hybrid greenhouse solar dryer developed by different researchers till now. The review helps the researcher in understanding the heat and mass transfer taking place inside the hybrid greenhouse and how it can be further improved.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 A
• /
• pp.36-38
• /
• 2004

This paper presents an application of parallel hybrid Genetic Algorithm-Tabu Search (GA-TS) algorithm to search an optimal solution of a recokiguration in distribution system. In parallel hybrid CA-TS, after CA operations, stings which are not emerged in the past population are selected in the reproduction procedure. After reproduction operation, if there are many strings which are in the past population, we add new random strings into the population, if there's no improvement for the predetermined iteration, local search procedure is executed by TS for the strings with high fitness function value. To show the usefulness of the proposed method, developed algorithm has been tested and compared on a distribution system in the reference paper.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 A
• /
• pp.446-448
• /
• 2004

This paper presents an application of parallel hybrid Genetic Algorithm-Tabu Search (GA-TS) algorithm to search an optimal solution of a service restoration in distribution system. In parallel hybrid GA-TS, after GA operations, strings which are not emerged in the past population are selected in the reproduction procedure. After reproduction operation, if there are many strings which are in the past population, we add new random strings into the population. If there's no improvement for the predetermined iteration, local search procedure is executed by f for the strings with high fitness function value. To show the usefulness of the proposed method, developed algorithm has been tested and compared on a practical distribution system in Korea.

• 인터넷정보학회논문지
• /
• 제22권1호
• /
• pp.1-11
• /
• 2021

Estimation of distribution algorithm (EDA) is a popular stochastic metaheuristic algorithm. EDA has been widely utilized in various optimization problems. However, it has been shown that the diversity of the population gradually decreases during the iterations, which makes EDA easily lead to premature convergence. This article introduces a hybrid estimation of distribution algorithm (EDA) with differential evolution (DE) based on self-adaptive strategy, namely HEDADE-SA. Firstly, an alternative probability model is used in sampling to improve population diversity. Secondly, the proposed algorithm is combined with DE, and a self-adaptive strategy is adopted to improve the convergence speed of the algorithm. Finally, twenty-five benchmark problems are conducted to verify the performance of HEDADE-SA. Experimental results indicate that HEDADE-SA is a feasible and effective algorithm.

• Journal of Electrical Engineering and Technology
• /
• 제3권2호
• /
• pp.177-183
• /
• 2008

The particle swarm optimization(PSO) has been shown to converge rapidly during the initial stages of a global search, but around global optimum, the search process becomes very slow. On the other hand, the genetic algorithm is very sensitive to the initial population. In fact, the random nature of the GA operators makes the algorithm sensitive to initial population. This dependence to the initial population is in such a manner that the algorithm may not converge if the initial population is not well selected. In this paper, we have proposed a new algorithm which combines PSO and GA in such a way that the new algorithm is more effective and efficient and can find the optimal solution more accurately and with less computational time. Optimal location of SVC using this hybrid PSO-GA algorithm is found. We have also found the optimal place of SVC using GA and PSO separately and have compared the results. It has been shown that the new algorithm is more effective and efficient. An IEEE 68 bus test system is used for simulation.

• 한국동물학회:학술대회논문집
• /
• 한국동물학회 1994년도 한국생물과학협회 학술발표대회
• /
• pp.229.2-229
• /
• 1994