• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.49-50
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• 2016

Recently in Korea, some studies on concrete that mass quantity of additives are substituted in order to respond to the government's Low Carbon Green Growth Policy are being conducted. As on of additives, FA as an industrial by-product is used in a large quantity. However, In some of the domestic FA refineries, since some quantity of concrete without passing through the refining process is released for sales for the reasons of the shortening of production time and the cost reduction, etc., it exerts a bad influence on the quality of concrete. Therefore, in this study, there was implemented an experiment on the effects of using an extreme quality of FA which is available for distributing domestically on the engineering characteristics of lean mortar. As a result, it was found that the quality of FA exerts its effect on the compression strength bigger than the flow property or the air volume.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.261-273
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• 2017

The control of the deformative behaviour of pre-stressed concrete roof elements for a satisfactory service performance is a main issue of their structural design. Slender light-weight wing-shaped roof elements, typical of the European heritage, are particularly sensitive to this problem. The paper presents the results of deformation measurements during storage and of both torsional-flexural and purely flexural load tests carried out on a full-scale 40.5 m long innovative wing-shaped roof element. An element-based simplified integral procedure that de-couples the evolution of the deflection profile with the progressive shortening of the beam is adopted to catch the experimental visco-elastic behaviour of the element and the predictions are compared with normative close-form solutions. A linear 3D fem model is developed to investigate the torsional-flexural behaviour of the member. A mechanical non-linear beam model is used to predict the purely flexural behaviour of the roof member in the pre- and post-cracking phases and to validate the loss prediction of the adopted procedure. Both experimental and numerical results highlight that the adopted analysis method is viable and sound for an accurate simulation of the service behaviour of precast roof elements.

• Journal of IKEEE
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• v.24 no.1
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• pp.127-131
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• 2020

Fuzzy C-Means(FCM) algorithm is frequently used as a representative image segmentation method using clustering. FCM divides the image space into cluster regions with similar pixel values, which requires a lot of segmentation time. In particular, the processing speed problem for analyzing various patterns of the current users of the web is more important. To solve this speed problem, this paper proposes an improved FCM (Improved FCM : IFCM) algorithm for segmenting the image into the Otsu threshold and FCM. In the proposed method, the threshold that maximizes the variance between classes of Otsu is determined, applied to the FCM, and the image is segmented. Experiments show that IFCM improves performance by shortening image segmentation time compared to conventional FCM.

• Biomedical Science Letters
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• v.24 no.3
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• pp.168-174
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• 2018

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by abdominal pain, rectal bleeding and diarrhea. Gastrodia elata Blume (GE) has been used for the treatment of various diseases including neurodegenerative diseases and inflammatory disease. However, there has been no information on whether GE regulates intestinal inflammation. The aim of this study is to elucidate whether GE can protect against dextran sulfate sodium (DSS)-induced colitis in a mouse model. The colitis mice were induced by drinking water containing 5% DSS for 7 days. Body weight, colon length and clinical score were assessed to determine the effects on colitis. The levels of inflammatory cytokines, tumor necrosis factor $(TNF)-{\alpha}$ and interleukin (IL)-6 in colitis tissue were also measured. The results showed that mice administrated with DSS showed clinical signs including weight loss and reduced colon length. GE inhibited the DSS-induced loss of body weight and shortening of colon and increased Disease activity index score. Additionally, we observed that GE suppressed the levels of $TNF-{\alpha}$ and IL-6 in DSS-treated colon tissues. Collectively, these findings provide experimental evidence that GE might be a useful therapeutic agent for patients with UC.

• Computers and Concrete
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• v.24 no.6
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• pp.513-525
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• 2019

In this work, an experimental research has been performed on Steel Fiber-Steel Reinforced Concrete (SFSRC)specimens subjected to four-point bending tests to evaluate the feasibility of mutual replacement of steel fibers and conventional reinforcement through studying failure modes, load-deflection curves, stiffness of characteristic points, stiffness degradation curves and damage analysis. The variables considered in this experiment included steel fiber volume percentage with and without conventional reinforcements (stirrups or steel fibers) with shear span depth ratios of S/D=2.5 and 3.5. Experimental results revealed that increasing the volume percentage of steel fiber decreased the creation and propagation of shear and bond cracks, just like shortening the stirrups spacing. Higher crack resistance and suturing ability of steel fiber can improve the stability of its bearing capacity. Both steel fibers and stirrups improved the stiffness and damage resistance of specimens where stirrups played an essential role and therefore, the influence of steel fibers was greatly weakened. Increasing S/D ratio also weakened the effect of steel fibers. An equation was derived to calculate the bending stiffness of SFSRC specimens, which was used to determine mid span deflection; the accuracy of the proposed equation was proved by comparing predicted and experimental results.

• Macromolecular Research
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• v.14 no.3
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• pp.383-386
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• 2006

High temperature size exclusion chromatography (SEC) has been used widely for the characterization of crystalline polymers, for which high temperature operation above the polymer melting temperature is required to dissolve the polymers. However, this high temperature operation has many advantages in SEC separation in addition to merely increasing polymer solubility. At high temperature the eluent viscosity decreases, which in turn decreases the column backpressure and increases the diffusivity of the analytes. Therefore, many reports on the high temperature operation of high performance liquid chromatography (HPLC) have focused on shortening the analysis time and enhancing the resolution. However, the application of high temperature SEC analysis to exploit the merits of high temperature operation is scarce. In this article, therefore, we report on a new apparatus design for high temperature SEC.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.9
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• pp.513-518
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• 2009

The building HVAC systems generally have very different qualities of performance and durability with the superintendent's interest in or capability of management and maintenance of them. The poor management of these systems finally lead to the shortening of the life expectancy and result in the increase of operating cost and energy consumption due to their low efficiencies. So it is necessary to develop tools to maintain adequately and to operate efficiently various building service equipments in order to cope with actively the global environment problems and energy crises. In this study the LCC based calculation program and package were developed, which could be used for analyses of the economic performance and determination of the reasonable maintenance time and methods of building HVAC systems.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.8
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• pp.661-668
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• 2016

Oil deflector prevents oil leakage that occurs in thermoelectric power plant at operating lubricant facilities. Vibration of rotating rotor-induced wear of aluminum tooth in existing oil deflector leads to oil leakage as well as life shortening of the tooth. In this study, an advanced oil deflector was developed for shock absorption and prevention of wear by decreasing clearance (from 0.5 mm to 0.2 mm) between rotor and tooth to minimize oil leakage, and by replacing 2 aluminum teeth in outmost of the oil deflector with hi-performance seal made of engineering plastic. The CFD results were compared between advanced vs. existing oil deflector to determine the amount of oil loss. Structural safety was verified through impact analyses according to the three kinds of engineering plastics, considering cost efficiency, and optimal material of hi-performance seal was chosen.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.2
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• pp.64-73
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• 1997

Canned type household circulating pump in the country almost depends on the act of imports, however it has disadvantage of low efficiency because an airgap of between rotor and stator is large and when the boiler is not used in a period of summer, a can and a rotor become adhered each other. Accordingly the pump is impossible to drive the initial state, and a lifetime of the pump gets shortening. To overcome these defects a electronic circulating pump by axial air-gap type brushless motor which is completely depart from the general idea for the conventional pump is developed. This paper is verified through experiments that the developed pump has good performance for reduction of size and noise, reo trenchment of cost, and improvement of efficiency in comparison with the conventional pump.

• Design & Manufacturing
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• v.9 no.2
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• pp.1-5
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• 2015

Recently, as small-sized display products such as mobile phones and digital cameras have become lighter and smaller, the size of electric signal delivery part, connector for the mobile display products, also, needs to become smaller, so high-density integration like shortening the distance between signal delivery media, conductors is necessary. With the micro and high-density integration of the connector, it is necessary to maintain contact to a certain degree for keeping intensity and delivering electric signal smoothly to prevent a defect with a specific impact. Accordingly, this study carried out a structural analysis according to the operating mechanisms of 0.16CHP Class Bottom Contact FPC Connector and 0.24CHP Class BTB Connector mostly used in small-sized mobile display products such as mobile phones and digital cameras. As a result of the analysis, both connectors had lower than 997MPa, yield strength of connector material C5240-XSH, so it is judged that permanent plastic deformation would not occur, and that a contact force between the connector and FPC film occurs to a certain degree, so that there would not be any defect in electric signal delivery.