• Proceedings of the Korean Vacuum Society Conference
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• 1996.06a
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• pp.67-67
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• 1996

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.325-330
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• 2001

One of the principal components of the KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak structure is the vacuum vessel, which acts as the high vacuum boundary for the plasma and also provides the structural support for internal components. Hyundai Heavy Industries Inc. has performed the engineering design of the vacuum vessel. Here the overall configuration of the KSTAR vacuum vessel was briefly described and then the design methodology and the analysis results were presented. The vacuum vessel consists of double walls, several ports, leaf spring style supports. Double walls are separated by reinforcing ribs and filled with baking/shielding water. The overall external dimensions of the main body are 3.39 m high, 1.11 m inner radius, 2.99 m outer radius, and made of SA240-316LN. The vacuum vessel was designed to be capable of achieving the base pressure of $1\times10^{-8}$ Torr, and also to be structurally capable of sustaining the vacuum pressure, the electromagnetic and thermal loads during plasma disruption and bakeout, respectively. The vacuum vessel will be baked out maximum $150^{\circ}C$ by hot pressurized water through the channels formed between double walls and the reinforcing ribs. A 3-D temperature distribution and the resulting thermal loads in the vessel were calculated during bakeout. It was found that the vacuum vessel and its supports were structurally rigid based on the thermal stress analysis. The maximum electromagnetic loads on the vacuum vessel induced by eddy and halo currents resulting from the engineering plasma radial and vertical disruption scenarios have been estimated. The stress analyses have been performed based on these electromagnetic loads and the resulting stresses at he critical locations of the vacuum vessel were within the allowable stresses.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.164-172
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• 2001

We measured the pumpdown curves of an A5083 vacuum chamber and analyzed the outgassing in terms of desorption energies of water. The outgassing curves follow a ~$t^{-1.15}$ behavior before bakeout, which can be described by the first-order desorption of water molecules in the oxide layer. Analysis of the curves reveals that there exist several adsorption sites on the surface for water in the pressure range of ~$10^{-5}\;-\;10^{ -8}$Torr. Measurements utilizing the throughput method show that the room temperature outgassing rate is ~1{\times}10^{-13}$ Torr $\ell$/s $\textrm{cm}^2$ after 24 - h bakeout at $100^{\circ}C$.

• Journal of the Korean housing association
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• v.17 no.4
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• pp.111-117
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• 2006

The harmfulness of HCHO and VOCs from construction material and furniture has been increased gradually. It must be need to prevent pollution materials' accumulation indoor effectively and to remove very small amount of harmful pollution materials in various plans, because these kinds of pollution materials greatly affect human body, Therefore, this study is focused to find out the improvements of Indoor Air Quality in execution of natural ventilation and bakeout to reduce indoor chemical pollution materials or not. After effects of indoor air quality by natural ventilation and bake-out being examined, it is follows the conclusion. As for the density change of TVOC and Toluene according to time lapse, in case the middle and high-story areas have bake-out, the density increased once, but it showed the gradual decrease after bake-out was stopped, and it was shown that it exceeded the standards recommended for newly built apartment. The bake-out is effective to discharge the HCHO and TVOC from the construction material and the furniture, and the natural ventilation is effective remove the indoor pollution materials.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.247-254
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• 2000

The base pressure of vacuum vessel of the KSTAR (Korea Superconducting Tokamak Advanced Research) Tokamak is to be a ultra high vacuum, $10^{-6}{\sim}10^{-7}Pa$, to produce clean plasma with low impurity containments. For this purpose, the KSTAR vacuum vessel and plasma facing components need to be baked up to at least $250^{\circ}C,\;350^{\circ}C$ respectively, within 24 hours by hot nitrogen gas from a separate baking/cooling line system to remove impurities from the plasma-material interaction surfaces before plasma operation. Here by applying the implicit numerical method to the heat balance equations of the system, overall temperature distributions of the KSTAR vacuum vessel and plasma facing components are obtained during the whole baking process. The model for 2-dimensional baking analysis are segmented into 9 imaginary sectors corresponding to each plasma facing component and has up-down symmetry. Under the resulting combined loads including dead weight, baking gas pressure, vacuum pressure and thermal loads, thermal stresses in the vacuum vessel during bakeout are calculated by using the ANSYS code. It is found that the vacuum vessel and its supports are structurally rigid based on the thermal stress analyses.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.5
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• pp.468-476
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• 2005

The purpose of this study is to investigate actual air quality in newly-constructed multi-family houses and to improve Indoor Air Quality (IAQ). The field measurement was conducted in four different newly-constructed multi-family house complexes in Seoul and one existing multi-family house complex in Kyong-gi province. The result of the measurement shows that indoor concentrations of Formaldehyde and TVOC in newly-constructed multi-family houses are much higher than the foreign standards. To establish a proper process for reducing indoor air pollutants, various experiments have been conducted; application of natural materials, bake-out practice, closure of all openings without ventilation, and use of mechanical ventilation system. The result indicates that three practices (natural materials, bakeout, mechanical ventilation) can reduce the level of indoor air pollutants almost in half during the experiments. However, each practice has its limitation and is insufficient to satisfy IAQ standards. Therefore, the study proposes a proper reduction process of indoor air pollutants which combines four different practices in time sequence.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.6
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• pp.468-476
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• 2006

The paper deals with the numerical analysis of contaminants emission from the material affected by temperature variation in floor heating system. Considering mass transfer and heat transfer theories, a computer program for the analysis of VOCs emission was made. To demonstrate the accuracy of the numerical solution, the prediction results and the measured data were compared. Using this program, emission rates of the materials in the bakeout space and the no bake-out space were compared to estimate the variation of emission rate.

• Land and Housing Review
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• v.4 no.4
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• pp.417-424
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• 2013

The purpose of this study was to investigate the characteristics of the indoor air quality by season. The surveyed houses were 48 new apartment complex in 2012 across the country. The houses were carried out the bakeout before the test. The measuring method was "Indoor air quality testing standards process" and the measured items were formaldehyde, benzene, toluene, ethylbenzene, xylene, styrene average emissions. All the items were more emitting during the summer. From June to September the average concentration of formaldehyde emission was higher than other seasons. The average emissions of benzene concentrations in all seasons were released in small quantities. Average emissions of toluene and ethylbenzene concentration from April to August showed slightly higher emissions. Xylene and styrene concentration showed the highest emissions at April, but without large deviations throughout the year.