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        검색결과 49

        2.
        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
        4.
        2021.03 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        Developments in cancer therapies and diagnostic techniques have improved the long-term survival of cancer patients. Certain cancer treatments, such as radiotherapy, often harm normal tissue as well as the specifically targeted cancer cells. High doses of radiation induce bone loss. This study investigated the effects of pentoxifylline (PTX) on radiation-induced bone loss in C3H/HeN mice. C3H/HeN mice were divided into sham and irradiation (3 Gy, gamma-ray, IR) groups. The irradiated mice were treated for 12 weeks with vehicle, PTX (p.o.) or PTX (s.c.). Grip strength, uterus weight, serum alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) level were measured. Tibiae were analyzed using micro-computed tomography. There were no significant differences in the degree of grip strength, body weight and uterine weight between IR group and PTX-treated group. Treatment of PTX significantly preserved trabecular bone volume, trabecular number, trabecular separation and bone mineral density of proximal tibia metaphysic. The administration of PTX lowered serum TRAP in IR mice, suggesting that PTX can reduce the bone resorptive rate in mice. Our experimental data support the protective role of PTX against bone loss in irradiated mice. Based on the findings of this study, development of PTXbased treatments is anticipated to address bone loss after radiotherapy. Prospective dose escalation studies are required to determine the appropriate dosage of PTX.
        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
        11.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We present our estimate of pole shift caused by the recent 31 largest earthquakes of magnitude over 8.0. After reviewing theory of perturbation in the Earth’s rotation, each co-seismic as well as post-seismic pole shifts by the earthquakes are acquired and illustrated. A total co-seismic excitation due to these earthquakes is (x1, x2)=(−3.35, 5.89) milliarcsec, which increased about twice the initial estimation when the post-seismic deformation is considered. The single largest co-seismic excitation by 2011 Japan earthquake was (x1, x2)=(−2.06, 2.36) milliarcsec, which corresponds to 9.7 cm pole shift on the surface of the Earth.
        4,000원
        13.
        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
        15.
        2014.02 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        17.
        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
        19.
        2012.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, I calculate the past and future dynamical states of the Earth-Moon system by using modified Lambeck’s formulae. I find that the ocean tidal effect must have been smaller in the past compared to its present amount. Even though the Moon is already in the spin-orbit synchronous rotational state, my calculation suggest that it will not be in geostationary rotational state in the next billion years or so. This is due to the associated Earth’s obliquity increase and slow retardation of Earth’s spin and lunar orbital angular velocities. I also attempt to calculate the precessional period of the Earth in the future. To avoid uncertainties in the time scale, the future state is described by using the Earth-Moon distance ratio as independent parameter. Effects due to solar tidal dissipation are included in all calculations.
        4,000원
        20.
        2011.10 구독 인증기관·개인회원 무료
        A total of 5,000 ethanolic and methanolic extracts of different plant species from 23 nations including Costa Rica, Vietnam, Philippines, India, South Africa, Pakistan and Peru were evaluated for their larvicidal activities against Aedes aegypti, the major vector of dangue, dangue hemorhagic fever and yellow fever. The larval mortalities were observed 24h after treating the larvae to the extracts. At 500 ppm, 179 extracts showed >80% larval mortality in the 24h exposure. Among the extracts tested, the highest larval mortality was observed in the extracts of Piper guianense, Piper nigrum, Piper mocropodum, Piper sem-immersum, Piper magen and Piper pubicatulum. The LC50 value of extract P. guianense, P. nigrum, P. mocropodum, P. sem-immersum, P. magen and P. pubicatulum were 8.84, 11.48, 8.84, 13.86, 9.48 and 10.12 ppm against Ae. aegypti. It is suggested that P. guianense, P. nigrum, P. mocropodum, P. sem-immersum, P. magen and P. pubicatulum can be developed as potent larvicidal agents against Ae. aegypti.
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