• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1327-1329
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• 2000

The thyristor among the power-semi-conductor elements, which has large current capacity and high voltage, is used widely nowadays. When the thyristor was being used to the long time, this element may be able to arise the system trip caused by changing the characteristic and dropping the performance. Therefore, it would be necessary to analyze the characteristic of element to maintain the stable operation of the system. In oder to analyze this characteristic, it would be need to test forward direction, reverse direction and leakage current by supplying the half-sine wave voltage. Among these testing, transient current condition is generated from the testing of leakage current. This transient current may be the main factor of the error in the precise measurement of leakage current. Therefore, this paper analyzes the relationship between supply voltage and transient current in measuring leakage current of the SCR, and then suggests the condition and cause of transient current as appearing the leakage current in the testing the leakage current.

• Smart Structures and Systems
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• v.25 no.3
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• pp.323-335
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• 2020

Magnetorheological elastomer (MRE), a smart material, is an innovative material for base isolation system. It has magnetorheological (MR) effect that can control the stiffness in real-time. In this paper, a new hybrid base isolation system combining two electromagnetic closed circuits and the roller bearing is proposed. In the proposed system, the roller part can support the vertical load. Thus, the MRE part is free from the vertical load and can exhibit the maximum MR effect. The MRE magnetic loop is constructed in the free space of the roller bearing and forms a strong magnetic field. To demonstrate the performance of the proposed hybrid base isolation system, dynamic characteristic tests and performance evaluation were carried out. Dynamic characteristic tests were performed under the extensive range of strain of the MRE and the change of the applied current. Performance evaluation was carried out using the hybrid simulation under five earthquakes (i.e., El Centro, Kobe, Hachinohe, Northridge, and Loma Prieta). Especially, semi-active fuzzy control algorithm was applied and compared with passive type. From the performance evaluation, the comparison shows that the new hybrid base isolation system using fuzzy control algorithm is superior to passive type in reducing the acceleration and displacement responses of a target structure.

• Korean Journal of Radiology
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• v.23 no.1
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• pp.112-123
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• 2022

Objective: To investigate the relationship between ¹⁸F-FDG PET/CT semi-quantitative parameters and the International Association for the Study of Lung Cancer, American Thoracic Society/European Respiratory Society (IASLC/ATS/ERS) histopathologic classification, including histological subtypes, proliferation activity, and somatic mutations. Materials and Methods: This retrospective study included 419 patients (150 males, 269 females; median age, 59.0 years; age range, 23.0-84.0 years) who had undergone surgical removal of stage IA-IIIA lung adenocarcinoma and had preoperative PET/CT data of lung tumors. The maximum standardized uptake values (SUVmax), background-subtracted volume (BSV), and background-subtracted lesion activity (BSL) derived from PET/CT were measured. The IASLC/ATS/ERS subtypes, Ki67 score, and epidermal growth factor/anaplastic lymphoma kinase (EGFR/ALK) mutation status were evaluated. The PET/CT semi-quantitative parameters were compared between the tumor subtypes using the Mann-Whitney U test or the Kruskal-Wallis test. The optimum cutoff values of the PET/CT semi-quantitative parameters for distinguishing the IASLC/ATS/ERS subtypes were calculated using receiver operating characteristic curve analysis. The correlation between the PET/CT semi-quantitative parameters and pathological parameters was analyzed using Spearman's correlation. Statistical significance was set at p < 0.05. Results: SUVmax, BSV, and BSL values were significantly higher in invasive adenocarcinoma (IA) than in minimally IA (MIA), and the values were higher in MIA than in adenocarcinoma in situ (AIS) (all p < 0.05). Remarkably, an SUVmax of 0.90 and a BSL of 3.62 were shown to be the optimal cutoff values for differentiating MIA from AIS, manifesting as pure ground-glass nodules with 100% sensitivity and specificity. Metabolic-volumetric parameters (BSV and BSL) were better potential independent factors than metabolic parameters (SUVmax) in differentiating growth patterns. SUVmax and BSL, rather than BSV, were strongly or moderately correlated with Ki67 in most subtypes, except for the micropapillary and solid predominant groups. PET/CT parameters were not correlated with EGFR/ALK mutation status. Conclusion: As noninvasive surrogates, preoperative PET/CT semi-quantitative parameters could imply IASLC/ATS/ERS subtypes and Ki67 index and thus may contribute to improved management of precise surgery and postoperative adjuvant therapy.

• Journal of the Korean Applied Science and Technology
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• v.26 no.1
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• pp.51-59
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• 2009

Natural Artemisia extraction was extracted from Artemisia component using diethyl ether as a solvent, and we tested various pharmacetical and chemical characteristics of this extract. Characteristic experiments to use natural Artemisia extract tested antimicrobial experiment using microbe in pharmacetical material, and tested dye experiment using fiber in chemical material. From the result of characteristics experiment, some conclusions are obtained as follow. From the result of extraction experiment, it obtained about 10.4%-Artemisia extraction ratio as semi-solid state, and after dried in freezing from Artemisia extract of semi-solid state, it obtained about 10%-Artemisia extraction ratio as solid state of dark blue-green color. From result of antimicrobial experiment of Artemisia extract, number of staphylococcus aureus (ATCC-01) and aspergillus niger (ATCC-02) in microbe decreased more and more according to time passage. This phenomenon showed that Artemisia extract influences to antimicrobial effect. From the result of dye experiment of Artemisia extract, it appeared in direction of dark blue-green color after dyed to use cotton and silk with fiber to control in pH 7.5. Specially the result which confirmed dye of fiber with optical electron microscope (OEM), we could know that it appears darker silk than cotton.

• The Journal of Engineering Geology
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• v.2 no.1
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• pp.58-69
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• 1992

Change in atmospheric pressure produce sizable fluctuafions in wells penetrafing confined aquifers. The relationship is inverse; that is, increases in atmospheric pressure produce decreases in water levels, and conversely. When atmospheric pressure changes are expressed in terms of a column of water, the raflo of water level change to pressure change expresses the barometric efficiency of an aquifer. In the study area, aquifers are developed in the fractures, joints, bedding planes and occasionally in solufion cavities of marl interbeds. The barometric efficiency of the aquifer varies from 8 to 90%, indicating that Confined, Unconfined and Semi-Confined condifions exist locally. The barometric efficiency is characteristic of the aquifer itself and observed in the field is inversely proportional to specific storage or the storage coefficient. It is remalned in question to derive the relationship between B.E. and S.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.263-268
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• 2008

Building Integrated PV(BIPV) is one of the best fascinating PV application technologies. To apply PV module in building, various factors should be reflected such as installation position, shading, temperature, and so on. Especially a temperature should be considered, for it affects both electrical efficiency of a PV module and heating/cooling load in a building. This study investigates a semitransparent PV module that is designed as finished material for windows. Therefore it needs to considerate about the optical characteristics of the transparent module. It reports the effect of thermal and optical characteristics of the PV module on generation performance. The study was performed by measuring sun spectrum and luminance through the PV modules and by monitoring the temperature and experiment. The results showed that 1 degree temperature rise reduced about 0.48% of output power.

• Journal of Korean Society of Steel Construction
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• v.8 no.3 s.28
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• pp.127-137
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• 1996

Connections as basic elements and an integrated part of a steel frame has an effect on the frame's performance. Conventional analysis and design techniques are based on either idealized fixed or pinned conditions. In fact, the use of rigid or pinned connection model in steel frame analysis serves the purpose of simplifying the analysis and design processes, but all connections used in current pratice possess stiffness and transfer moment which fall between the extreme cases of fully rigid and ideally pinned. To predict the behavior of the semi-rigid steel frames, it is necessary to predict the moment-rotation behavior of the beam-to-column connections. In this research, prediction equation for moment-rotation behavior of the beam-to-column connection is suggested and the effect of design parameters has investigated. Prediction model, in a nondimensional form shows the moment-rotation characteristic for connections. It is composed of the curve fitting power function using standardization constant K and 4 parameter $KM_o$, ${\theta}_0$, b, n based on the pretest result about moment-rotation behavior of connection.

• Journal of the Korean Applied Science and Technology
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• v.26 no.3
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• pp.341-349
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• 2009

Natural grape extraction was extracted from grape component using diethyl ether as a solvent, and we tested various pharmaceutical and chemical characteristics of this extract. Characteristic experiments to use natural grape extract tested antimicrobial experiment using microbe in pharmaceutical material, and tested dye experiment using fiber in chemical material. From the result of characteristics experiment, some conclusions are obtained as follow. From the result of characteristics experiment, it obtained about 7.5%-grape extraction ratio as semi-solid state, and after dried in freezing from grape extract of semi-solid state, it obtained about 10%-grape extraction ratio as solid state of dark purple color. From result of antimicrobial experiment of grape extract, number of staphylococcus aureus (KCMC-01) and aspergillus niger (KCMC-02) in microbe decreased more and more according to time passage. This phenomenon showed that grape extract influences to antimicrobial effect. From the result of dye experiment of grape extract, it appeared in direction of dark purple color after dyed to use cotton and silk with fiber to control in pH 7.5. Specially the result which confirmed dye of fiber with optical electron microscope(OEM), we could know that it appears darker silk than cotton.

• Journal of the Korean Home Economics Association
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• v.46 no.8
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• pp.17-26
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• 2008

The purpose of this study was to identify the aesthetic characteristics of modern fashion design use with a particular focus on transparency, and to help create future vision and feature. As part of the methodology for this study, I examined the concept of transparency, its characteristics and how it was expressed through art, architecture and other designs using literature research. Furthermore, I performed justifiable analysis on modern fashion design which used transparency from the 1990s till present. The following concepts were deciphered from information: Firstly, the concept of purity was highlighted. The emphasis here was to enhance the body's natural beauty with simple silhouettes that do not restrict its curves, using light materials such as clear vinyl, semi-clear materials or thin chiffon. Secondly, to express sensuality by exposing the body's curves with tight wrapping using clear materials, or with indirect and symbolic see-through techniques using contrasting clear, semi-clear and opaque materials. Thirdly, to express futurism through cyber and electronic images using high tech or shiny materials such as metal or holograms. Mechanical movements or effects of light are also used. Fourthly, to express playful characteristic by promoting surprises and disharmony that contradict with traditional techniques. This is carried out by intentionally exaggerating certain portions of clothes through disorder elements or confusion, and unsymmetrical shapes which destruct the human body's normal form.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.649-652
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• 2005

It is reported that semi-solid forming process takes many advantages over the conventional forming process, such as long die lift, good mechanical properties and energy saves. Rheology material has a thixotropic, pseudo-plastic and shear-thinning characteristic. Therefore, general plastic or fluid dynamic analysis is not suitable for the behavior of rheology material. So it is difficult for a numerical simulation of the rheology process to be performed because complicated processes such as the filling to include the state of the free surface and solidification in the phase transformation must be considered. Moreover, it is important to predict the deformation behavior for optimization of net shape forging process with semi-solid materials and to control liquid segregation for mechanical properties of materials. In this study, so, molecular dynamics simulation was performed for the control of liquid segregation in compression experiment as a part of study on analysis of rheology forming process.