• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.33-33
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• 1999

The design of a vacuum pumping system for the KOMAC (Korea Multipurpose Accelerator Complex) RFQ(Radio-Frequency Quadrupole) linac is described. [Fig] Resulted from the lost proton beam, gas streaming from the LEBT (Low Energy Beam Transport) and out-gassing from the surfaces of the RFQ cavity and vacuum plumbing, the total gas load will be on the order of 7.2$\times$10-4 Torr-liters/sec, consisting mainly of hydrogen. The system designed to pump on a continual basis with redundancy to ensure that the minimal operating vacuum level of 1.0$\times$10-6 Torr is maintained even under abnormal conditions. Details of the design, performance analysis and the preliminary test results of the cryogenic pumps are presented.

• International journal of advanced smart convergence
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• v.7 no.4
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• pp.84-91
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• 2018

In this paper, we simulated three different HV systems and analyzed of each vacuum characteristics by VacCAD modelling. In each of modelled vacuum systems, selection of chamber materials, combination of rough pump with high vacuum pump and conductance of roughing line (diameter and length) were proposed as system variables. In the modelling of chamber materials, the pumping times to ultimate pressures of different chamber materials (stainless steel, aluminum) were compared by the variations of chamber volume. In this model, the effects of outgassing dependent on the chamber materials was also simulated and aluminum was estimated to optimum chamber materials. It was also obtained that modelling of vane and roots pump with diffusion pump and diameter, length of $50{\times}250$ [mm]roughing line were characterized as optimum variables to reach the ultimate pressure of 10E-7 [mbar] most effectively. Optimum design factors for vacuum characteristics of modelled vacuum system were achieved by VacCAD simulations. Feasibility of VacCAD as vacuum simulator was verified and applications of VacCAD expected to be increased to fields in vacuum needed.

• Applied Science and Convergence Technology
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• v.23 no.6
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• pp.309-316
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• 2014

A large particle accelerator requires an ultrahigh vacuum (UHV) system of average pressure under $1{\times}10^{-7}$ Pa for mitigating the impact of beam scattering from the residual gas molecules. The surface inside the beam ducts should be controlled with an extremely low thermal outgassing rate under $1{\times}10^{-9}Pa{\cdot}m^3/(s{\cdot}m^2)$ for the sake of the insufficient pumping speed. To fulfil the requirements, the aluminum alloys were adopted as the materials of the beam ducts for large accelerator that thanks to the good features of higher thermal conductivity, non-radioactivity, non-magnetism, precise machining capability, et al. To put the aluminum into the large accelerator vacuum systems, several key technologies have been developed will be introduced. The concepts contain the precise computer numerical control (CNC) machining process for the large aluminum ducts and parts in pure alcohol and in an oil-free environment, surface cleaning with ozonized water, stringent welding process control manually or automatically to form a large sector of aluminum ducts, ex-situ baking process to reach UHV and sealed for transportation and installation, UHV pumping with the sputtering ion pumps and the non-evaporable getters (NEG), et al. The developed UHV technologies have been applied to the 3 GeV Taiwan Photon Source (TPS) and revealed good results as the expectation. The problems of leakage encountered during the assembling were most associated with the vacuum baking which result in the consequent trouble shootings and more times of baking. Then the installation of the well-sealed UHV systems is recommended.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1658-1665
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• 1989

Reactor design considerations over several critical parameters for a planar type reactive ion etcher are given. The etch uniformity is taken as a principal design constraint. The characteristics of economicaly available vacuum pumping system are taken as practical design constraints. A set of theoretical conditions on the chamber geometry and on the gas delivery and vacuum system, that satisfy the design constraints, are derived from basic properties of RF glow discharge and gas dynamics. The theoretical results are applied to decide design parameters of a practical single-wafer-per-chamber planar type reactive ion etching machine.

• International journal of advanced smart convergence
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• v.11 no.4
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• pp.88-95
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• 2022

Vacuum simulation is associated with the prediction and calculation of how materials, pumps and systems will perform using mathematical equations. In this investigation, three different high vacuum systems were simulated and estimated with each vacuum characteristics by VacTran simulator. In each of modelled vacuum systems, selection of gas loads into vessel, combination of rough and high vacuum pumps and dimension of conductance elements were proposed as system variables. In pump station model, the pumping speed to pressures by the combination of root pump was analyzed under the variations of vessel volume. In this study, the effects of outgassing dependent on vessel materials was also simulated and aluminum vessel was estimated to optimum materials. It was obtained from the modelling with diffusion pump that the diameter, length of 50×250[mm]roughing line was characterized as optimum variables to reach the ultimate pressure of 10E-7[torr]. Optimum design factors for vacuum characteristics of modelled vacuum system were achieved by VacTran simulator. Feasibility of VacTran as vacuum simulator was verified and applications of VacTran in high tech process expected to be increased.

• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.516-520
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• 2010

Parametric study has been conducted to calculate the capacity of vacuum pump system that will be used to maintain the pressure of the tube structure under atmosphere level. Recently many railroad researchers pay attention to the tube train system as one of the super high speed transportation system. To achieve the super high speed, the inside of tube system should be maintained at low pressure level. In the low pressure environment, it is well known that air resistance of train is drastically decreased. Vacuum pump system will be used to make low pressure state for tube structure, exhaust the leakage air and supplement additional vacuum pumping. As results of these studies, we get the lump capacity of vacuum pump for various parameters. These results can be applied to analyze the effects of the reduction of air resistance.

• Journal of the Korean Vacuum Society
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• v.2 no.4
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• pp.480-485
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• 1993

Factros considered building the magnetron sputtering system for TFT LCD (thin film transistor liquid crystal display0 metallization were thin film thichnes uniformity, temperature uniformity and the pressure gradient of sputtering gas flow in vacuum chamber, base pressure, and the stability fo the carrier moving . The system was consisted of a deposition chamber, a pre-heating chamber, a RF-precleaning chamber and a load/unload lock chamber. The system was designed to handle a substrate with dimension of 400$\times$400mm. The temperautre uniformity of a heater table developed showed $250 ^{\circ}C\pm$5% accuracyon the substrate glass. A base pressure of 1.8 $\times$10-7 torr was obtained after 24 hours pumping with a cryo pump. After an aluminum target was installed in a sputtering source and the film wa sdeposited on the glass, the uniformity, reflectivity and sheet resistance of the deposited film were measured.

• Vacuum Magazine
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• v.4 no.1
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• pp.16-23
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• 2017

Recently, KSTAR, Korea's superconducting fusion energy research and development device, has succeeded in driving the high performance plasma for 70 seconds for the first time in the world. Continuous plasma operation technology is an essential factor for commercialization of fusion energy power generation. Therefore, this achievement is expected to play a major role in the research of fusion technology required for future fusion power plants. In order to operate the KSTAR, the discharge process in which the neutral gas is turned into the plasma should be preceded in the start-up (breakdown) phase of tokamak operation. This process essentially involves the vacuum environment in the tokamak device. KSTAR has successfully operated a vacuum pumping system to achieve the target level of the vacuum environment through a high temperature baking operation, a discharge cleaning process and boronization.

• Vacuum Magazine
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• v.2 no.4
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• pp.39-46
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• 2015

After stepping into a new field of vacuum 30 years ago, our company has grown up steadily as a specialized vacuum industry, and now we can provide vacuum devices covering most of the pressure range. We are planning to put out high level dry pump like a multistage Roots pump on the market in the near future. Procedures of technology development for designing, fabricating, and testing the multistage Roots pump of 600 L/min class will be briefly reported. Core items of the technical development on the multistage Roots pump are as follows; elaborated profile design of 3-lobe rotors using an involute curve, optimization of rotor dimensions, especially for clearances and rotor width, considering the pumping speed, compression ratio and heat load, and establishment of a standardized test system. At present, the multistage Roots pump is about to come into commercialization.

• Geomechanics and Engineering
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• v.19 no.5
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• pp.447-462
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• 2019

The vacuum preloading method has been used in many countries for ground improvement and land reclamation works. A sand cushion is required as a horizontal drainage channel for conventional vacuum preloading. In terms of the dredged-fill foundation soil, the treatment effect of the conventional vacuum preloading method is poor, particularly in Tianjin, China, where a shortage of sand exists. To solve this problem, straight-line vacuum preloading without sand is widely adopted in engineering practice to improve the foundation soil. Based on the engineering properties of dredged fill in Lingang City, Tianjin, this paper presents field instrumentation in five sections and analyzes the effect of a prefabricated vertical drain (PVD) layout and a vacuum pumping method on the soft soil ground treatment. Through the arrangement of pore water pressure gauges, settlement marks and vane shear tests, the settlement, pore water pressure and subsoil bearing capacity are analyzed to evaluate the effect of the ground treatment. This study demonstrates that straight-line vacuum preloading without sand can be suitable for areas with a high water content. Furthermore, the consolidation settlement and consolidation degree system is developed based on the grey model to predict the consolidation settlement and consolidation degree under vacuum preloading; the validity of the system is also verified.