• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.359-359
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• 2011

Many research applications in basic sciences and biology such as protein crystallography require hard x-rays in the range of 3-20 keV with high brightness. A medium energy storage ring as PLS-II with a beam energy of 3 GeV can meet such high photon energies. In-vacuum undulators (IVU) with a period length of 20 mm and a peak field of 0.97 T are used in the PLS-II ring to produce such X-rays in the fundamental or higher harmonics. Due to the many poles and high fields, insertion devices like wigglers and undulators have a significant impact on the stability of the electron beam with potential degradation of beam quality and life time. Therefore, nonlinear fields must be determined by measurement and evaluated as to their impact on beam stability. Specifically, transverse field roll-off can be a serious detriment to injection in top-up mode and must be corrected. We use magnetic field measurement data to evaluated beam stability by tracking particles using an explicit symplectic integrator in both, transverse and longitudinal planes.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1996년도 제11회 학술발표회 논문개요집
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• pp.68-68
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• 1996

• Journal of Mechanical Science and Technology
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• 제16권9호
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• pp.1065-1071
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• 2002

The friction and wear behaviors of magnetron sputtered MoS$_2$ films were investigated through the use of a pin and disk type tester. The experiments were performed for two kinds of specimens (ground (Ra 0.5 $\mu\textrm{m}$) and polished (Ra 0.01 $\mu\textrm{m}$) substrates) under the following operating condifions : linear sliding velocities in the range of 22～66 mm/s (3 types), normal loads varying from 9.8～29.4 N(3 types) and atmospheric conditions of air, medium and high vacuum (3types). Silicon nitride pin was used as the lower specimen and magnetron sputtered MoS$_2$ on bearing steel disk was used as the upper specimen. The results showed that low friction property of the MoS$_2$ films could be identified in high vacuum and the specific wear rate in air was much higher than that in medium and high vacuum due to severe oxidation. It was found that the main wear mechanism in air was oxidation whereas in high vacuum accumulation of plastic flow and adhesion, were the main causes of wear.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1795-1797
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• 2001

This machine is a high-vacuum exhaust sealing device which makes the inside of PDP element in high vacuum state, blows inactive gases into it and finally seals it. This machine consists of vacuuming parts, heating parts and exhausting parts. Applying the energy saving technology, this machine improves the temperature uniformity of vacuuming and heating parts.

• 반도체디스플레이기술학회지
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• 제1권1호
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• pp.41-45
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• 2002

In modem manufacturing, new applations and technologies demand smaller, and functional devices to replace large systems. As miniaturization becomes a necessity, many companies are interested in small pumps for use in creating ultra-high vacuum, but past efforts to develop such systems have failed due to problems with vibration, stress, heat and power consumption. This paper shows analysis-based design techniques for high vacuum turbomolecular pump by finite element analysis.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권5호
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• pp.632-639
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• 2014

Mechanical stress and the vacuum level are the two main factors dominating the quality factor of a resonator operated in the vacuum range 1 mTorr to 10 Torr. This means that if the quality factor of a resonator is very insensitive to the mechanical stress in the vacuum range, it is sensitive to mainly the ambient vacuum level. In this paper, a wafer-level packaged MEMS resonator with a highly vacuum-sensitive quality factor is presented. The proposed device is characterized by a package with out-of-plane symmetry and a suspending structure with only a single anchor. Out-of-plane symmetry helps prevent deformation of the packaged device due to thermal mismatch, and a single-clamped structure facilitates constraint-free displacement. As a result, the proposed device is very insensitive to mechanical stress and is sensitive to mainly the ambient vacuum level. The average quality factors of the devices packaged under pressures of 50, 100, and 200 mTorr were 4987, 3415, and 2127, respectively. The results demonstrated the high controllability of the quality factor by vacuum adjustment. The mechanical robustness of the quality factor was confirmed by comparing the quality factors before and after high-temperature storage. Furthermore, through more than 50 days of monitoring, the stability of the quality factor was also certified.

• 한국정밀공학회지
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• 제26권3호
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• pp.88-97
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• 2009

The vacuum die casting techniques can diminish the porosity of products and provide better surface appearance by the ordinary high pressure die casting process. The vacuum system can also reduce the cold laps in the die casting process and minimize the overflow pockets of the die. The vacuum system does not need high pressures to die cast compared to the ordinary die casting process, and so enables die casting of large parts for a given machine size. Parts made by the vacuum system have higher strength and more elongation than parts made by the ordinary die casting systems. In this paper, we designed and produced the Magnesium seat frames using the vacuum die casting processes. The new Magnesium seat frame was designed to satisfy safety regulations. Some safety test procedures of the seat frame were simulated by the finite element method. We obtained 10% weight reduction by design modification of seat frames compared to the current model. Flow simulations were carried out to minimize the trial and error in producing the parts. The die casted parts using vacuum systems resulted in better mechanical characteristics and no defects compared to those without vacuum systems.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.361-364
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• 2009

마이크로 인공위성에 적용가능한 마이크로 추력기를 개발하기 위해서는 우주환경을 모사할 수 있는 진공설비가 요구된다. 본 논문에서는 $10^{-5}\;torr$의 진공도를 목표로 정하고 진공설비를 구축하였고, $100{\sim}120\;km$의 고도를 모사한다. 장치 선정 및 실제 장치 구축 후 진공도 성능 실험을 수행하였고 저진공 펌프를 작동시켜 누센펌프의 멤브레인에 따른 특성연구를 진행하였다. 또한 향후 열진공챔버로의 전환을 위한 계획을 서술하였다.

• 한국진공학회지
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• 제2권4호
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• pp.520-524
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• 1993

• 한국진공학회:학술대회논문집
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• 한국진공학회 1996년도 제10회 학술발표회 논문개요집
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• pp.80-80
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• 1996