• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.144-149
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• 2005

In this paper, insulations characteristics by temperature changes($+30{\sim}-40[^{\circ}C]$) of $SF_6$ gas in the experimental chamber were studied. From this result, The breakdown characteristics classify the vapor stage of $SF_6$ according the Paschen's law, the gas & liquid coexisted stage of voltage value increases & much deviation and the VB low stage as the interior of chamber gets filled with mixture of $SF_6$ that are not liquefacted and remaining air which couldn't be ventilated. In addition the ability of insulation of liquid $SF_6$ was higher than that of the highly pressurized $SF_6$ gas. In this research, we want to provide the base data on designing insulation of high-temperature superconductor and the cryogenic equipments by investigating the insulation characteristics of $SF_6$.

• Membrane Journal
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• v.15 no.1
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• pp.22-33
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• 2005

Asymmetric PVDF membranes were prepared by the phase inversion from casting solutions containing PVDF, NMP as solvent and 1,4-dioxane, DGDE, acetone, or GBL as additives by immersing them in water. The effects of various additives on the casting solution properties, permeation properties, and membrane structures were investigated. Low miscibility of 1,4-dioxane, DGDE and acetone with the coagulant (water) compared with NMP resulted in reducing the membrane pore size. When DGDE is used as an additive, the pore size was reduced because of its incipient sharp interface formation in the water. GBL increased membrane pore size because of its polarity compared to that of NMP. The PVDF membranes with various pore sizes could be obtained by controlling the amount of additive. The effect of mixed solvent (aqueous and non-aqueous solution) on permeation through membrane was investigated. Not only solution viscosity but surface tension affected solvent permeation.

• Membrane Journal
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• v.25 no.6
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• pp.547-557
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• 2015

In this study, we synthesized polyimide with high carbon dioxide gas transport property using 2,2-bis(3,4-carboxylphenyl) hexafluoropropane, 2,3,5,6-tetramethyl-1,4-phenylenediamine and poly(ethylene glycol) bis(3-aminopropyl) terminated and then we calculated solubility parameter of synthesized polymer and non-solvent phase separation coefficient to determine proper solvent for preparation of asymmetric membrane, also we measured the viscosity of the polymer solution to check polymer contents in membrane solution and prepare asymmetric membrane with $LiNO_3$ additives. The morphology and gas separation property of membrane prepared by phase separation method was confirmed using Field Emission Scanning Electron Microsope and the single gas permeation measurement apparatus. We confirmed that the carbon dioxide permeance of the membrane increased and the selectivity showed little change with decreasing of the volatile solvent contents.

• Membrane Journal
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• v.22 no.1
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• pp.62-71
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• 2012

In this study, for preparation of gas separation membrane with high permeability, hydroxy polyimide was synthesized using 6FDA and APAF. Synthesis of HPI was confirmed by H-NMR and FT-IR, thermal property of membrane was characterized by Differential scanning calorimetric (DSC) and thermogravimetric analyzer (TGA). Especially, the synthesized HPI can possible to search conversion to PBO at $450^{\circ}C$. To obtain the membrane having high permeability, ternary system consist of polymer, solvent and non-solvent additive was introduced, asymmetric HPI flat sheet membrane was prepared by phase inversion method. Finally, the change of morphology with each component was observed through FE-SEM.

• Membrane Journal
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• v.33 no.3
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• pp.110-126
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• 2023

In this review, the approaches, properties, and elements involved in the formation of polymeric membranes for various materials are discussed. The present research emphasizes the proficiency in several membrane formation processes such phase inversion, interfacial polymerization, stretching, track etching, and electrospinning. Additionally, the obstacles and applicability of various application manufacturing processes are addressed. Various polymeric membranes are reviewed with regard to significant surface properties such as surface roughness, surface tension, surface charge and surface functional group. Additional enhancements of popular membrane formation processes like phase inversion and interfacial polymerization are required to ensure advancements in membrane efficiency. Analysing the possibilities of modern manufacturing practices like track etching and electrospinning is also crucial.

• Tuberculosis and Respiratory Diseases
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• v.46 no.4
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• pp.489-499
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• 1999

Background: The patient with bronchiectasis may have obstructive ventilatory impairment combined with mild restrictive ventilatory impairment due to fibrosis of surrounding lung parenchyme and pleural adhesions caused by chronic recurrent pulmonary infections. Since hyperinflation or emphysematous change can be occured in bronchiectasis, pulmonary functions such as lung volumes and diffusing capacity may also vary with associated emphysema. Methods: For the evaluation of lung volumes and diffusing capacity in bronchiectasis with respect to the anatomic types and severity of bronchiectasis, a total of 40 cases comprising 24 cases of tubular, and 16 cystic type of bronchiectasis were analyzed retrospectively. Correlation between lung functions and extent of bronchiectasis or associated emphysema detected in HRCT were also evaluated. Results: Vital capacity(VC) tended to decrease in cystic type than in tubular type. As the severity of bronchiectasis became serious, the VC were significantly reduced, whereas the total lung capacity(TLC), residual volume(RV) and its ratio to the total lung capacity(RV/TLC) had no significant difference. Lung clearance index(LCI) was significantly increased in cystic type than in tubular type, whereas the slope of phase III in single breath nitrogen curve($\triangle$N2/L) was not significantly changed regard to the type and severity of bronchiectasis. DLCO and DLCO/VA reflecting diffusing capacity were significantly decreased in cystic type and also as the severity of bronchiectasis became serious. The correlation coefficient of VC, DLCO and LCI with the extent of bronchiectasis were -0.322, -0.339 and 0.487, respectively, whereas other parameters were not significantly correlated with the extent of bronchiectasis. VC and DLCO correlated negatively with the extent of emphysema while RV, RV/TLC, LCI and $\triangle$N2/L correlated positively. Conclusion: These findings suggest that the reduction of VC and diffusing capacity or uneven distribution of inspired gas in bronchiectasis are related to both the extent of bronchiectasis and associated emphysema while increased residual volume be related to the extent of associated emphysema alone.

• Journal of Sasang Constitutional Medicine
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• v.10 no.1
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• pp.101-142
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• 1998

1. Objects The base of classification of Sasang Constitution was the different congenital formation of organs such as lungs, spleen, liver, kidneys, and it was expanded from the viscera region of lungs, spleen, liver, kidneys to the body shape of trunk. The researched about body shape of Sasang Constitution have had points of issues which derived by measurement with hands. But this study was measured the characteristics of body shape putting in importance of anatomical position with the computerized 3-Dimension scanner, which minimized the errors of measurement, and it was abled the cubic measurement such as volume, area of cross section as well as round length. 2. Materials & Method The examinee was healthy male 40 persons and female 20 persons from 20's to 40's, who was diagnosed by the specialist of Sasang Constitutional Medicine. The body shape was measured round length, area of cross section, and volume of 31 anatomical points and the 25 hypothesis with the Rapid 3D Color Scanner Model 3030 RGB/PS. And the characteristics of each constitution's body shape was derived. 3. Results & Concousion In female, Taeumin had the largest trunk and Soeumin had the smallest trunk compared to other constitution, but Soyangin had only the smallest neck. Soeumin has the smallest round length of nipple and the $CV_{12}$, and Soyangin has the smallest breadth of ASIS. Soyangin had the smallest volume from thyroid bone to the highest points of armpits and from sternum to nipple. Taeumin had the largest volume from sternum to the $CV_{12}$ and from sternum to xiphoid process. In male, Taeumin had the largest trunk and Soeumin had the smallest trunk from the level of thyroid bone to ASIS. Soyangin has the longest distance and Soeumin has the shortest distance from nipple to the lowest of breast. Taeumin had the largest volume of trunk and Soeumin had the smallest volume of trunk. In the ration of four-Cho, Taeumin had the longest distance from the highest points of armpits to nipple and Soyangin had the shortest distance of that. Soyangin had the smallest ratio of the height of upper middle cho. Soeumin had the smallest ratio from the $CV_{12}$ to navel among trunk. In the correlation among the four Cho, Taeumin had the negative correlation between the Upper-Cho and the Lower-Middle-Cho significantly.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.165-172
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• 1997

CRT용 고전압 형광체인 ZnS를 저전압용에 적용하기 위해 ZnS 분말표면에 졸-겔법으로 SnO$_2$코팅조건을 연구하였다. Sn의 코팅량은 Sn/ZnS=0.02~0.07 범위에서 변화시켰으며, 코팅된 ZnS분말의 열처리는 450~90$0^{\circ}C$/2hr 범위에서 수행하였다. Sn/ZnS=0.035일 때 최적의 코팅이 이루어졌으며, 과도한 열처리는 ZnS에서 ZnO로 상전이가 발생하므로 500~$600^{\circ}C$ 정도가 안전한 조건임이 규명되었다. Sn량이 증가할수록 코팅된 ZnS의 형광강도는 감소하였으나 저전압 형광특성은 향상될 수 있는 가능성을 보여주었다.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.287-288
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• 2003

Polyurethane(PU) materials have been generally used in the automobile, paint, furniture, adhesive, and textile industries. The use of Waterborne PU was motivated form the environmental point of view, i.e. reduction of solvent emissions into the atmosphere(volatile organic compounds, VOC)[1]. Generally speaking, phase change materials (PCM) have the capability of absorbing or releasing thermal energy to reduce or eliminate heat transfer at the temperature range of the particular temperature stabilizing material[2]. (omitted)

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.824-829
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• 2011

EMS-type Maglev vehicle maintains constant levitation air-gap between electromagnet and guideway by using gap sensor. The other words, when Maglev vehicles levitating over the guideway, mass of the vehicle effects through 1st (electromagnetic air-gap control) and 2nd (air-spring) suspension to grider. Resonace between electromagnetic suspension and grider could be occurred, which causes instability and poor ridecomfort. This paper is to test the dymanic interaction between levitation air-gap and switching system grider that has less mass and high natural frequencies than other type of general girders.