• 제어로봇시스템학회논문지
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• 제18권3호
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• pp.230-236
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• 2012

Shielding the air-gap magnetic field of the electrodynamic wheel below a conductive plate and opening the shielding plate partially, a thrust force and a normal force generate on the conductive plate at the open area. But, as only the variable controlling both forces is a rotating speed of the electrodynamic wheel, it is very difficult to control the forces independently by the speed. So, we discuss a novel method controlling the forces effectively through manipulating a size of the open area. The independent control is made possible by virtue of the feature that the relative ratio between both forces is irrelevant to an air-gap length and determined uniquely for a specific rotating speed of the wheel. Therefore, the rotating speed and the size of open area become new control variables. The feasibility of the method is verified experimentally. Specially, the controllable magnetic forces are used in a noncontact conveyance of the conductive plate.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.120-127
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• 1998

This paper deals with the dynamic responses of the multi-span continuous bridge with longitudinal shear keys. It is motivated by a need to understand the effects of longitudinal shear keys which may be used for the reduction of the longitudinal seismic force in continuous bridges. The results show that (1) The force reduction of fixed pier is proportional to the ratio of gap size and elastic maximum displacement of the bridges without shear keys ; (2) The thermal movement has little effect on the response of the continuous bridges with shear keys. Also the simplified equation is proposed to calculate the maximum response of the continuous bridges with longitudinal shear keys. The equation requires only the elastic analysis results of the bridge and the gap size between superstructure and shear keys.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.601-604
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• 1993

The effect of an insulator inserted along the axis of a red-to-plane gap on an ion flow field in $SF_6$ gas is investigated experimentally in the pressure region where a proceeding corona discharge exists. Without the insulator, the calculated electric field on the plane electrode agrees fairly well with the measured one. With the insulator, the ion flow field characteirstics may be attributed to the change in the electric field distribution by the accumulated charge, the increase in the ratio of the dielectric strength in gas gap to that along the insulator surface with the gas pressure, and the thermal diffusion of ions near the insulator.

• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1331-1335
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• 2011

We report the results of the characterization of Cu oxide thin films deposited by radio frequency (r.f.) magnetron sputtering at different annealing temperatures. The deposited Cu oxide thin films were investigated by scanning electron microscopy, spectroscopic ellipsometry, X-ray diffraction, atomic force microscopy, Xray photoelectron spectroscopy, and contact angle measurements. The thickness of the films was about 180 nm and the monoclinic CuO phase was detected. The $CuO_2$ and $Cu(OH)_2$ phases were grown as amorphous phase and the ratio of the three phases were independent on the annealing temperature. The surface of Cu oxide films changed from hydrophilic to hydrophobic as the annealing temperature increased. This phenomenon is due to the increase of the surface roughness. The direct optical band gap was also obtained and laid in the range between 2.36 and 3.06 eV.

• Journal of Information Display
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• 제2권4호
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• pp.39-45
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• 2001

The voltage controlled ramp(VCR) waveform has recently been introduced in the reset period prior to addressing for plasma display. However, this method results in the oscillation of the gap voltage when the ramp rate is increased so as to reduce reset period. In this paper a current controlled ramp(CCR) waveform method in the reset period is suggested. This method can suppress the oscillation of gap voltage under the condition of shorter ramp time. Moreover, the reset time can be reduced by about 30 % compared with the VCR method under the same background luminance.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.60-61
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• 2020

In this study, the recycled fine aggregates produced from the waste concrete by using Jaw crusher depending on crushing gap of Jaw crusher were studied to offer a solution for recycled fine aggregate for concrete. The results of the experiment showed that the factors that influence grading and water absorption ratio, density and grain shape were significantly characterized by the generation of the particulate matter and the crushing shape of the aggregate.

• 공업화학
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• 제18권5호
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• pp.438-443
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• 2007

본 연구에서는 티타늄 산화막을 상온에서 HCP (hollow cathode plasma) 반응기에 의하여 증착하였다. HCP 반응기에 대한 시뮬레이션 결과, 전극에서의 열 발생에 관계없이 기판 표면에서의 온도분포는 일정하였다. 그리고 전극과의 거리가 증가하면서 기판 표면에서의 유체는 일정한 것으로 나타났으며, 표면 조도는 거리에 따라 감소하였다. 출력이 증가할수록 산소의 조성은 증가하는 것으로 나타났으며, 출력이 240 watt와 반응 거리가 3 cm에서 Ti와 O의 비율이 1 : 2에 가깝게 결합이 이루어졌다.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.1118-1124
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• 2023

Experimental study on the fluidelastic instability (FEI) of a curved tube bundle in single phase downward cross flow is investigated for the design qualification and analysis input preparation of helical coiled steam generator tubing. A 6×9 normal square curved tube array with equal and different vertical/horizontal pitch-to-diameter ratio was under-tested up to 6 m/s in term of gap flow velocity to measure the critical velocity for FEI. The critical velocity for FEI was measured at the turning point from the vibration amplitude plot along the gap flow velocity. Our test results were compared with straight tube results and published data in the design guideline. The applicability of the current design guidelines to a curved tube bundle is also assessed. We found that introducing frequency difference in a curved tube array increases the critical velocity for fluidelastic instability.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.598-603
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• 2003

A CFD analysis has been performed to investigate turbulent heat transfer in a triangular rod bundle with a pitch-to-diameter ratio(P/D) of 1.06. Anisotropic turbulence models predicted the turbulence-driven secondary flow in the triangular subchannel and the distributions of time mean velocity and temperature showing significantly improved agreement with the measurements over the linear standard ${\kappa}-{\varepsilon}$. The anisotropic turbulence models predicted turbulence structure in large flow region fairly well but could not predict the very high turbulent intensity of azimuthal velocity observed in narrow flow region(gap).

• 한국진공학회지
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• 제4권S1호
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• pp.130-137
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• 1995

Deopsition of thermal quality SiO2 using a high density plasma ECR CVD process has been demonstrated to give void and seam free gap fill of high aspect ratio metallization structures with a simple oxygen-silane chemistry. This is achieved by continuous sputter etching of the film during the deposition process. A two-step process is utilized to deposit a composite layer for higher manufacturing efficiency. The first step, which has a deposition rate of approximately 0.5 $\mu$m/min., is used to provide complete gap fill between the metal lines. The second step, which has a deposition rate of up to 1.5 $\mu$m/min., is used to deposit a total thickness of 2.0$\mu$m for the intermetal dielectric film. The topography of this composite film is very compatible with subsequent chemicl mechanical polishing(CMP) planarization processing.