• 한국수학교육학회지시리즈E:수학교육논문집
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• 제36권4호
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• pp.627-644
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• 2022

본 연구에서는 아르키메데스의 삽입방법에 기반한 다양한 각의 삼등분 도구들을 조사하고, 일부 도구들을 제작하여 특징을 비교하였다. 이를 통해, 삼등분 도구의 제작 및 활용에서 사용의 편이성, 삼등분되는 각의 임의성, 구조의 간결성 등의 요소를 고려해야 한다는 것을 알았다. 기술한 요소들을 고려하여, 수학교실에서 활용할 수 있는 각의 삼등분 도구로 Veprtskii가 1888년에 제안한 도구에 주목하였다. 본 연구에서는 Veprtskii가 제안한 방법을 개선하여 나무젓가락과 철끈을 이용하여 각의 삼등분 도구를 제작하였다. 이때, 제작된 도구는 첫째, 다른 삼등분 도구에 비해 부품의 개수가 적고, 구조나 제작도 간단하였고, 둘째 사용 방법도 편리하며, 셋째 특정한 각이 아닌 임의의 각의 삼등분을 나타내며, 넷째 제작 비용이 저렴하고 제작 과정도 간단했다. 이 도구는 수학교실에서 삼각형의 외각의 성질, 이등변삼각형의 성질과 관련된 탐구 활동에서 폭넓게 활용될 수 있을 것으로 기대된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.79-79
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• 2009

Samples of Ta-doped in $In_2O_3-ZnO-SnO_2$(IZTO) with a doping level up to 4wt% were sintered at $1600^{\circ}C$ in $O_2$. The crystal phase of the samples was identified by an X-ray diffraction experiment. apparent density and porosity with sintered temperature from $1500^{\circ}C$ to $1640^{\circ}C$ are mesured by archimedes method. For each sample, the specific resistivity was determined. samples of sintered at $1600^{\circ}C$ had the highest density and lowest porousity and The Ta 0.25-wt%-doped IZTO ceramics had the lowest resistivity.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2016년도 제54차 하계학술대회논문집 24권2호
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• pp.167-168
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• 2016

본 논문에서는 스마트폰을 이용하여 수학을 공부할 수 있는 지오지브라의 활용 방안을 제안하였다. 특히 원 및 원기둥 등 도형의 면적 계산 개념을 제안한 아르키메데스의 사고를 지오지브라를 활용하여 할 수 있는 구체적인 자료를 개발하였다. 이러한 자료를 통해 학생들은 도형의 면적을 구하는 공식을 암기하기 않고 스스로 이해하면서 아르키메데스가 제안한 불가불량의 개념을 통해 다양한 도형의 면적과 체적을 구하는 방법을 이해할 수 있을 것이다. 특히 수학을 어려워하는 학생들에게 머릿속으로 사고하기 어려운 내용을 컴퓨터라는 도구를 활용하여 이해할 수 있도록 하였다는 점에서 의미가 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.643-648
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• 2001

The direct simulation Monte Carlo(DSMC) method is applied to investigate steady and unsteady flow fields of a single-stage disk-type drag pump. Two different kinds of pumps are considered: the first one is a rotor-rotor combination, and the second one is a rotor-stator combination. The pumping channels are cut on a rotor and stator. The rotor and stator have 10 Archimedes' spiral blades, respectively. In the present DSMC method, the variable hard sphere model is used as a molecular model, and the no time counter method is employed as a collision sampling technique. For simulation of diatomic gas flows, the Borgnakke-Larsen phenomenological model is adopted to redistribute the translational and internal energies. The DSMC results are in good agreement with the experimental data.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.807-812
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• 2001

The effects of casing shapes on the interaction of the impeller and volute in a small-size turbo-compressor are investigated. Numerical analysis is conducted for the compressor with circular and single volute casings from inlet to discharge nozzle. In order to predict the flow pattern inside the entire impeller, vaneless diffuser, and casing, calculations with a multiple frame of reference method between the rotating and stationery parts of the domain are carried out. For incompressible turbulent flow fields, the continuity and three-dimensional time-averaged Navier-Stokes equations are employed. To predict the performance of two types of casings, the static pressure and loss coefficients are obtained with various flow rates. Also, static pressure distributions around casings are studied for different casing shapes, which are very important to predict the distribution of radial load.

• 한국레이저가공학회지
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• 제6권1호
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• pp.9-16
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• 2003

Micromachining using the DPSS 3rd Harmonic Laser (355nm) has outstanding advantages as a UV source in comparison with Excimer lasers in various aspects such as maintenance cost, maskless machining, high repetition rate and so on. It also has the greater absorptivity of many materials in contrast to other IR sources. In this paper, the process for micro-drilling of blind hole in Cu/PI/Cu substrate with the DPSS UV laser and the scanning device is investigated by the experimental methods. It is known that there is a large gap between the ablation threshold of copper and that of PI. We use the Archimedes spiral path for the blind hole with different energy densities to ablate the different material. Finally, the blind via hole of diameter 100$\mu\textrm{m}$ and 50$\mu\textrm{m}$ was drilled.

• 대한수학회보
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• 제52권2호
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• pp.571-579
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• 2015

Archimedes showed that the area between a parabola and any chord AB on the parabola is four thirds of the area of triangle ${\Delta}ABP$, where P is the point on the parabola at which the tangent is parallel to the chord AB. Recently, this property of parabolas was proved to be a characteristic property of parabolas. With the aid of this characterization of parabolas, using centroid of triangles associated with a curve we present two conditions which are necessary and sufficient for a strictly locally convex curve in the plane to be a parabola.

• 방사성폐기물학회지
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• 제15권2호
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• pp.117-124
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• 2017

Densities of molten salt mixtures of eutectic LiCl-KCl with $UCl_3$, $CeCl_3$, or $LaCl_3$ at various concentrations (up to 13 wt%) were measured using a liquid surface displacement probe. Linear relationships between the mixture density and the concentration of the added salt were observed. For $LaCl_3$ and $CeCl_3$, the measured densities were significantly higher than those previously reported from Archimedes' method. In the case of $LiCl-KCl-UCl_3$, the data fit the ideal mixture density model very well. For the other salts, the measured densities exceeded the ideal model prediction by about 2%.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 춘계학술대회 논문집
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• pp.291-298
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• 2004

The observations of rapid motion of bubbles under water for approximately 50 ms or less in high-magnetic fields of 10 T have been carried out successfully for the first time. The observation system constructed is composed of a high-speed video camera, a telescope, a cryostat with a split-type superconducting magnet, a light source, a mirror and a transparent sample cell. Using this system, the influence of magnetic field on the path and shape of single bubbles of O$_2$ (paramagnetism) and N$_2$ (diamagnetism) has been examined carefully. Experimental values describing the path are in good agreement with theoretical values calculated on the basis of the magneto-Archimedes effect, despite the effect of magnetism on the bubble. However, no effect of magnetism on the shape of the bubble is observed. In addition, the influence of magnetic field on drag coefficient of the bubble is discussed.

• Carbon letters
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• 제13권3호
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• pp.151-156
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• 2012

This study considered the effect of the heat treatment temperature on the compressive strength of coal powder compacts affected by density, porosity, and crystallinity. Coal powder compacts were made by pressing of milled coal powder and were heat treated at 200, 400, 600, 800, and $1000^{\circ}C$. The density and porosity of the heat treated specimens at each temperature were measured using the Archimedes method and changes in crystallinity were analyzed using Raman spectroscopy. Increases in compressive strength at $600^{\circ}C$ or higher temperatures were proportionally related to increases in the density and the degree of crystallinity.