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        검색결과 31

        3.
        2021.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Meta-heuristic algorithms have been developed to efficiently solve difficult problems and obtain a global optimal solution. A common feature mimics phenomenon occurring in nature and reliably improves the solution through repetition. And at the same time, the probability is used to deviate from the regional optimal solution and approach the global optimal solution. This study compares the algorithm created based on the above common points with existed SA and HS to show advantages in time and accuracy of results. Existing algorithms have problems of low accuracy, high memory, long runtime, and ignorance. In a two-variable polynomial, the existing algorithms show that the memory increases and the accuracy decrease. In order to improve the accuracy, the new algorithm increases the number of initial inputs and increases the efficiency of the search by introducing a direction using vectors. And, in order to solve the optimization problem, the results of the last experiment were learned to show the learning effect in the next experiment. The new algorithm found a solution in a short time under the experimental conditions of long iteration counts using a two-variable polynomial and showed high accuracy. And, it shows that the learning effect is effective in repeated experiments.
        4,000원
        7.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        One of the most performed action in daily life is standing up from sitting position. As the population of the world is aging at the high rates, people may face problems with reduced muscle strength as well as psychological changes. This can lead elderly people having difficulties with standing up from chair. Now, with the aging trend worldwide, products are being developed that can support the lives of the elderly. This study examines the distribution of hip pressure in relation to the seating positions of the standing assistance seats under development to prevent standing up accidents in older adults. The currently developing standing assistant chair designed to tilt to a maximum angle of 25 degrees. At over 25°, design considers that older people are at risk of thrown back out of that force and that the forces exerted on their arms and legs can be a significant burden to older people. By considering danger of higher than 25° for older people which is experimented in the basis of static capturing approach in previous papers, it is experimented people with age group of 20~60 on 0° to 25° tilting angle on the basis of dynamic capturing method in order to pick convenient angle of inclination. Moreover, tried to find the optimum angle by comparing the hip pressure distribution when seated at the edge of the seat and at the center of the seat with the pressure distribution sensor.
        4,000원
        14.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Gravitational interactions — mergers and y-by encounters — between galaxies play a key role as the drivers of their evolution. Here we perform a cosmological N-body simulation using the tree-particle-mesh code GOTPM, and attempt to separate out the effects of mergers and y-bys between dark matter halos. Once close pair halos are identified by the halo finding algorithm PSB, they are classified into mergers (E12 < 0) and y-by encounters (E12 > 0) based on the total energy (E12) between two halos. The y-by and merger fractions as functions of redshift, halo masses, and ambient environments are calculated and the result shows the following: (1) Among Milky-way sized halos (0:33-2:0 X 1012h-1M⊙), 5:37±0:03% have experienced major y-bys and 7.98±0.04% have undergone major mergers since z ~ 1; (2) Among dwarf halos (0:1 - 0.33 X 1012h-1M⊙), 6.42 ± 0.02% went through major y-bys and 9.51 ± 0.03% experienced major mergers since z ~ 1; (3) Milky-way sized halos in the cluster environment experienced fly-bys (mergers) 4-11(1.5 - 1.7) times more frequently than those in the field since z ~ 1; and (4) Approaching z = 0, the y-by fraction decreases sharply with the merger fraction remaining constant, implying that the empirical pair/merger fractions (that decrease from z ~ 1) are in fact driven by the fly-bys, not by the mergers themselves.
        3,000원
        19.
        2012.12 구독 인증기관 무료, 개인회원 유료
        To evaluate the acute to chronic effects of crude oil exposure on hematological and blood biochemical toxicities, Sprague-Dawley rats were given oral doses of 0, 50, or 100 mg/kg BW/day of Iranian heavy crude oil for a period of four weeks. In the acute phase of exposure (one day after four weeks of oil treatment), decreases in weight of thymus, serum level of interferon gamma (IFN-γ), superoxide dismutase (SOD), and catalase activities in liver or kidney, and increase in weight of adrenal gland occurred after oral administration of crude oil. In body weight, histopathological examination, hematological and blood biochemical analyses in the acute phase of exposure, no significant differences were observed among the experimental groups. In the subchronic and chronic phase of exposure (two months and six months after four weeks of oil treatment), the changes of biomarkers were normalized, except the indicators of oxidative stress. Our findings showed that the bioassay on the indicators of oxidative stress is a sensitive method for determining exposure to crude oil in rats.
        4,000원
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