• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.667-670
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• 2005

본 논문은 100um와 80um의 텅스텐 와이어를 이용하여 세라믹(Ceramic)기판에 홀(Hole)을 뚫어 텅스텐 와이어를 수직으로 세우는 방식으로 수직형의 마이크로 스프링을 제작하였다. 마이크로 스프링의 설계를 위해 제한된 실험 결과와 신경회로망을 이용하여 텅스텐 와이어의 두께와 높이, 쉬프트(Shift)의 양을 변화시키면서 장력(Tension force)을 모델링하였고 제작을 통해 검증하였다. 이는 기존의 수평형 프로브카드의 한계를 대체할 수 있는 수직형 프로브카드의 핵심 모듈로서 멀티다이(Multi Die) 뿐만 아니라 범핑(Bumping)타입의 칩 테스트도 가능하다.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.5
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• pp.617-623
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• 2003

In the present study, the characteristics of upward bubble flow were experimentally investigated in a liquid bath. The velocity of upward bubble flow was calculated for two different experimental conditions：1) bubble flow without kinetic energy 2) bubble flow with kinetic energy. Bubble flow without kinetic energy starts to undergo the effect of buoyancy l0cm away from the nozzle. Whereas. kinetic energy is dominant before 30 cm away from the nozzle in bubble flow but after this point kinetic energy and inertial force are applied on bubble flow at the same time In addition, as the flow rate increases the maximum velocity point moves to the nozzle. The velocity Profiles near free surface is extremely irregular due to surface flow. Gas volume fraction is high near the nozzle due to gas concentration. but decreases with the increasement of axial position. Gas volume fraction does not vary after the axial position, z=60 in spite of the increasement of flow.

• Journal of Mechanical Science and Technology
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• v.14 no.8
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• pp.891-899
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• 2000

The flame speed may be decomposed into the burning speed and the flame transport speed. The flame transport speed is affected considerably by the flow direction, variation rate of flow direction, and flow speed in the combustion chamber. Especially, the flow direction and the variation rate of flow direction at the spark plug location during the ignition period have an important effect on the ignition process and the early flame propagation process. We measured the flow direction component and the variation rate of flow direction with a hot wire probe at the spark plug location. It was shown that the representative flow direction of ignition period is the right-vertical direction of crank shaft and it was used to investigate the variation rate of flow direction.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.411-416
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• 1993

In order to achieve computer-oriented control and automation of manufacturing processec, a distributed NC (DNC_) system was developed for FMS under the Windows environment. The DNC system consists of conventional DNC, PMC interface and tool management modules. Real-time system conditon monitoring and control fuctions required for machine tools and machining processes were accomplished by developing a PMC interface module called MMC board. Tool condition monitoring and management was performed by the developed tool management module composed of a tool setting probe and softwares. Performance of the DNC system was confirmed on the horizontal and the vertical type machining center equipped with FANUC OMC for the large amount of experiments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.2899-2908
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• 2000

Methodology of volumetric error identification is presented to improve the accuracy of NC machine tools by using a reference artifact and a touch trigger probe. Homogeneous transformation matrix and kinematic chain are used for modeling the geometric and thermal errors of a three-axis vertical machining center. The reference artifact is designed and fabricated to identify the model parameters by machine tool metrology. Parameters in the error model are able to be identified and updated by direct measurement of the reference artifact on the machine tool under the actual conditions which include the thermal interactions of error sources. The proposed method can speed up and simplify volumetric error identification processes.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.228-232
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• 2003

It has recently been shown that the instability of thin film of a nanoscale can be used in the processes of building nano-size structures, which have potential practical importance in nanotechnology. Molecular dynamics simulation is conducted to probe the thin fluid film of a nano-size and its dynamic behavior during destabilization and structure formation. Non-continuum characteristics are shown in the properties like pressure tensor, viscosity, and thermal conductivity. The thermocapillary force induces a slow growth of long waves in the scale considered. A long-range interaction with the solid wall induces vertical structures, whose formation time and space between neighbors are proportional to the strength of the interaction.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.279-279
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• 2012

In order to estimate the average migration lengths of $H_3O^+$ ions in amorphous ice, we conducted experiments of reactive ion scattering (RIS), low energy sputtering (LES), and reflection absorption IR spectroscopy (RAIRS) with an ultra-high vacuum (UHV) chamber. Dopped water-ice films were grown on the clean surface of Ru single crystal and analyzed with RIS, LES and RAIRS methods. The population changes of probe molecules, which were buried at a controlled distance from the surface, were monitored by those methods so that we can mesure the migration efficiencies. From the measured efficiencies, we evaluated the average migration lengths. This result is expected to give the information about the dynamics of proton in water-ice film.

• Journal of Surface Science and Engineering
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• v.32 no.2
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• pp.83-92
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• 1999

GaN etching was performed using planar inductively coupled $Cl_2$-based plasmas and the effects of main process parameters on the characteristics of the plasmas and their relations to GaN etch rates were studied. Also, the GaN etch mechanism was investigated using a Langmuir probe and optical emission spectroscopy (OES) during the etching, and X-ray photoelectron spectroscopy (XPS) of the etched surfaces. The GaN etch rates increased with the increase of chlorine radical density and ion energy, and a vertical etch profile haying the etch rate close to 4000 $\AA$/min could be obtained. The addition of 10% Ar to $Cl_2$ gas increased the GaN etch rate and the addition of Ar (more than 20%) and HBr generally reduced the GaN etch rate. The GaN etch rate appeared to be more affected by the chemical reaction between Cl radicals and GaN compared to the physical sputtering itself under the sufficient ion bombardments to break GaN bonds.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.4
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• pp.505-514
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• 1998

Flow pattern of air-water two phase flow depends on the conditions of pressure void fraction and channel geometry. We classify the flow pattern by measuring the output signal of the conductivity probe. under the classified flow pattern we mount a visualization equipment on the test section and take pictures. We vary the concentration of pure solvent and polymer to measure local void fraction. We know that the maximum point position of local void fraction distribution move from the center of the pipe to the wall of the pipe as JSL increase when JSA is constant in two phase flow. But we find that the maximum point position of local void friction move from the wal of the pipe to the center of the pipe when polymer concentration increase.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.161-164
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• 2000

Currently, Atomic Force Microscope(AFM) has been widely used to measure the surface topography of a sample by detecting interaction force between atoms on the sample and extremely sharp probe tip. The vertical resolution of AFM is mainly determined by external vibration noise. The resolution of AFM shows different values for the different environment, thus it is necessary to determine relationship between the criteria and the resolution of AFM regardless of environment. In this paper, we discuss the allowable level of floor vibration for AFM equipment at given resolution. The vibration criteria can be used as reference data to design mechanical structure and to analyze the structural dynamics of AFM equipment.