• Journal of Sensor Science and Technology
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• v.29 no.5
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• pp.354-359
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• 2020

The high vacuum hermetic sealing technique ensures excellent performance of MEMS resonators. For the high vacuum hermetic sealing, the customization of anodic bonding equipment was conducted for the glass/Si/glass triple-stack anodic bonding process. Figure 1 presents the schematic of the MEMS resonator with triple-stack high-vacuum anodic bonding. The anodic bonding process for vacuum sealing was performed with the chamber pressure lower than 5 × 10^-6 mbar, the piston pressure of 5 kN, and the applied voltage was 1 kV. The process temperature during anodic bonding was 400 ℃. To maintain the vacuum condition of the glass cavity, a getter material, such as a titanium thin film, was deposited. The getter materials was active at the 400 ℃ during the anodic bonding process. To read out the electrical signals from the Si resonator, a vertical feed-through was applied by using through glass via (TGV) which is formed by sandblasting technique of cap glass wafer. The aluminum electrodes was conformally deposited on the via-hole structure of cap glass. The TGV process provides reliable electrical interconnection between Si resonator and aluminum electrodes on the cap glass without leakage or electrical disconnection through the TGV. The fabricated MEMS resonator with proposed vacuum packaging using three-layer anodic bonding process has resonance frequency and quality factor of about 16 kHz and more than 40,000, respectively.

• Journal of the Korean Vacuum Society
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• v.21 no.6
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• pp.287-294
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• 2012

In the high vacuum condition of the space, outgassing from any assembly of satellite can contaminate satellites, especially second surface mirror and optical lens, it cause satellite to fail in own missions. Therefore, all unit shall be check for compatibility with vacuum using CVCM (Collected Volatile Condensable Material) and TML (Total Mass Loss) in advance. CVCM and TML of the PZT-5 piezoelectric ceramic vibrator has less than 0.1% and 1.0% respectively. Also, it has less than 500 $ng/cm^2/hr$ of Thermoelectric Quartz Crystal Microbalance for vacuum bake-out test using high temperature(more than $80^{\circ}C$) and high vacuum (less than $5.0{\times}10^{-3}$ Pa). Thus, piezoelectric ceramic vibrator may be employed in the vacuum environments. Finally, it can be confirmed that the characteristics change of the piezoelectric ceramic vibrator is less than 1% under vacuum environments.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.30-30
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• 2000

당사는 각종 진공 장비를 개발/제작한 경험을 바탕으로 25년 동안 진공 산업 발전에 기여하여 왔으며 자체 기술로 HIGH VACUUM 응용시스템 설계 및 제작하고 있다. 이와 함께 3D CAD를 이용한 consulting 및 Modeling 분석을 수행하여, 자체 기술로 설계 및 제작 판매하고 있다. Vacuum System은 In-line System (ITO, SiO2, Cr Tio2, Ag, Al 등), Roll to Roll(Web) Sputtering system (ITO, SiO2, Ar, Metal 등), 유기 EL 박막 진공 증착 장치, PECVD System, Evaporator 시스템 등을 제작 공급하고 있다. 현재 Roll to Roll(Web) Sputtering System은 Dual Cathode를 사용하는 방식으로 개발중에 있으며, 평판 디스플레이용 대면적 Glass를 위한 In-line Sputtering System을 같이 개발하고 있다.

• Journal of the Korean Vacuum Society
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• v.16 no.4
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• pp.235-243
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• 2007

Nowadays, in our country, large vacuum chambers for huge experimental facilities such as the tokamak fusion device, high power neural beam test stand, and space simulator have been constructed. In such a vacuum chamber of very large size, it is quite complicate to check on leakage quantitatively, while the probability of a leak is relatively high. To investigate the feasibility of applying reliably a helium leak detection to the huge vacuum chambers, and to find a reasonable methodology of choosing an optimum set-up for leak detection, several virtual constructions of the leak detection system have been analyzed by calculating the pressure distribution in the system and the helium level in the sensor part.

• Journal of Biosystems Engineering
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• v.28 no.6
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• pp.525-530
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• 2003

This study was carried out to develop a vacuum nozzle seeder for the automation of large seeds sowing of fruit vegetables and rootstocks. Moreover, the seeding efficiency was examined to find the optimum operating condition considering high precision seeding. The important operating factors for high seeding rate were typically nozzle diameter and absorbing vacuum pressure. The optimum nozzle diameters were found 1.5, 1.5 and 2.0 mm for Chambak, Tuktozwa and Hukjong while the optimum vacuum pressures were 8.0㎪, 10.6㎪ and 5.3㎪, respectively. Under the optimum operating condition, the results indicated that the maximum seeding rates were 97.6％, 98.8％ and 97.6％ respectively for Chambak Tuktozwa and Hukjong. The vibrating acceleration of the hopper did not make any significant effects on the seeding rate when the vacuum pressure reached 8.0㎪ and the sowing rate became higher with lighter seed. As the seed became heavier, the larger diameter of nozzle was recommended 1.5mm of the nozzle diameter was found to be applied for the experimental seeds. The vacuum pressure was also found 8.0㎪ - 13.3㎪ at that time.

• Journal of the Korean Vacuum Society
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• v.4 no.2
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• pp.135-141
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• 1995

Spinning Rotor Gauge(SRG)를 전달표준기(transfer standard gauge)로 사용하여 한국표준과학연구원(KRISS)의 고진공표준과 이태리 표준연구소인 IMGC(Istituto 야 Metrologia Gustavo Colonnetti)고진공표준의 국제비교를 실시하였다. 그 방법은 SRG의 accommodation coefficient(s)를 각 연구실의 고진공표준기로 측정하여 그 결과를 비교하였다. 이 결과 두 기관에서 교정한 SRG 볼의 $\sigma$값의 평균차이는 0.696%로서 양국의 고진공표준은 오차범위내에서 일치하는 것으로 나타났다.

• Journal of the Korean Chemical Society
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• v.11 no.1
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• pp.17-21
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• 1967

For utilization of Bunker-C residual oil produced at KOCO., the auther tested the properties of vacuum fraction and blown asphalt, and as the result of it, (1) Vacuum fraction had so broad range of viscosity and high flash point that could be produced all kind of lublicating oil, but had to be dewaxed for high pour point, (2) Urea dewaxing was suitable to lighter fraction but not to heavier fraction, so, for heavier fraction, solvent dewaxing was needed. (3) Blown asphalt produced from vacuum residue had uniform relation between softening point and penetration in spite of broad change of blowing condition and adding of catalyst.

• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.195-200
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• 2017

A mobile lab kart for plasma training is developed with a high vacuum pumping system, vacuum gauges and a glass discharge tube powered by a high voltage transformer connected to a household 60 Hz line. A numerical model is developed by using a commercial multiphysics software package, CFD-ACE+ to analyze the experimental data. Simulations for argon and nitrogen were carried out to provide fundamental discharge characteristics. Variations of the kart configuration were demonstrated: a glass tube with three electric probes, optical emission spectrometer attachment and infra red thermal imaging system to give more detailed analysis of the discharge characteristics.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.70.1-70.1
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• 2015

The facility for RAON superconducting heavy-ion accelerator at a beam power of up to 400 kW will be produced rare isotopes with two electron cyclotron resonance (ECR) ion sources. Highly charged ions generated by the ECR ion source will be injected to a superconducting LINAC to accelerate them up to 200 MeV/u. During the acceleration of the heavy ions, a good vacuum system is required to avoid beam loss due to interaction with residual gases. Therefore ultra-high vacuum (UHV) is required to (i) limit beam losses, (ii) keep the radiation induced within safe levels, and (iii) prevent contamination of superconducting cavities by residual gas. In this work, a RAON vacuum design for all the accelerator system will be presented along with Monte Carlo simulation of vacuum levels in order to validate the vacuum hardware configuration, which is needed to meet the baseline requirements.

• Journal of the Korean Vacuum Society
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• v.8 no.4A
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• pp.391-396
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• 1999

KSTAR vacuum vessel mockup was fabricated by Korea Heavy Industries. The fabrication technology chosen for the mockup is introduced and assessed in this paper. KSTAR vacuum vessel is a huge vacuum chamber of 52 cubic meters never built in this country. Through the experiency of the KSTAR mockup fabrication, welding methods for obtaining both ultra high vacuum and structural integrity of the large vacuum chamber are extracted. The fabrication and assembly techniques for the complicated structure composed of reinforced ribs, double walls and various ports are also developed. A nondestructive test on the welding spot was performed and the results show that no major leaks violating the criterion were found. The one of the main objectives of the mockup fabrication is to measure the dimensions of the structure before and after fabrication, which plays an important role in the fabrication and the assembly. By assaying the problems occurred during mockup fabrication, the KSTAR mockup will provide the techniques for the fabrication of the main vacuum vessel.