• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.11 no.2
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• pp.102-110
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• 2001

To establish an accurate asbestos analysis method for workplace samples, chrysotile, amosite, crocidolite, tremolite, actinolite, and anthophyllite asbestos fibers were analyzed for their morphology, atomic content and electron diffraction patterns. The morphology of asbestos fiber was evaluated in $10,000{\times}$ magnification. The atomic contents was analyzed by X-ray analyzer (TEM-EDX). Asbestos fibers were further assessed using electron diffraction (ED) patterns to provide an additional criterion for classifying the asbestos fibers. Twenty asbestos fibers were initially randomly selected for morphological evaluation; based on an aspect ratio (length : diameter = 3:1). Then the fibers were determined for their EDX spectrums and ED patterns. Our results showed that only chrysotile fiber has a hollow tube structure to be distinguished from other asbestos fibers. Although asbestos fibers had similar morphology, they had different EDX spectrums and ED patterns. Our results on the atomic content of asbestos fibers were very similar to those of other researchers, but amosite and crocidolite had a little difference in atomic content compared with the results from other researchers. The difference may be due to the difference in equipment or asbestos sample selection. A study on asbestos samples from biological specimens to establish a criterion for determining occupational asbestos exposed diseases should be done in the near future.

• Journal of the Korea Concrete Institute
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• v.26 no.1
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• pp.63-70
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• 2014

This experimental study was intended to improve the compressive strength of multi-walled CNT reinforced cementitious composites with efficiency. The variables considered are the degree of sonication, the amount of surfactant, the replacement ratio of silica fume, etc. Optical microscope informed that fiber dispersion of CNT was improved with the increase of sonication time, and the compressive strength was proved to be enhanced as the degree of sonication increased. When superplasticizer as a surfactant had SP/CNT ratio of 4~6, the best improvement in strength was obtained. Silica fume was shown to produce the highest compressive strength at 10% replacement. Microstructure of CNT composites was also analyzed; XRD and SEM results indicated that CNT addition hardly changed hydration products and microstructure, and MIP analysis found the reduction of total porosity as well as the increase of nano-pores with the size of tens of nm instead of the decrease of pore distribution in the region of around 10 ${\mu}m$ and 100 nm. The results of microstructure analysis explains that the strength improvement is closely related to physical contribution rather than chemical influence by adding CNT.

• Journal of the Korea Concrete Institute
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• v.19 no.6
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• pp.795-802
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• 2007

Recently, various strengthening methods using carbon fiber sheets (CFS) have been developed for the rehabilitation of structures and applied to the concrete member. However, still research need arises in order to verify the structural capacity of RC member which experienced bond loss between concrete and CFS after strengthening. This is because previous research has focused on the development of design process and evaluation of structural capacity only for retrofit. The appearance of this loss may be initiated at just after retrofit construction. And it will be more serious when the layer number of CFS increases. In order to minimize above mistake in retrofit design using CFS, more exact evaluation process to predict the bond loss of CFS is required. The objective of this research is to study the variation of flexural structural capacity of beam which has experienced bond loss after strengthening using CFS. Experimental and analytical study are performed and evaluation of the previous formula is conducted. Test result showed that the significant strength deterioration was not found until the bond loss of 20%. Overall structural behavior of the beams can be predicted by nonlinear sectional analysis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.12
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• pp.1988-1993
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• 2013

The aims of this study were to investigate the quality characteristics of yellow layer cake added with Sparassis crispa powder that were abundant in dietary fiber, and also to determine the most suitable amount of added S. crispa powder. Dried powder of S. crispa containing 61.8 g/100 g insoluble dietary fiber was added to the cake batter in Baker's percentage of 1%, 2%, 4%, and 8%. Cake batter containing 1% and 2% S. crispa powder showed similar pH, specific gravity, and viscosity values to the batter without S. crispa powder (control). As the amount of added S. crispa power increased, the volume, specific volume, baking loss, and brightness (for both crust and crumb) of the cake containing the powder tended to decrease. A greater amount of added S. crispa powder resulted in a decrease in hardness, gumminess, and chewiness of the cake containing the powder and also reduced the changes in hardness of the cake during 8 days of storage. The sensory analysis showed that cake containing 2% S. crispa had several desirable kinds of sensory attributes, such as color, flavor, taste, and texture compared to the control; whereas an addition of more than 2% S. crispa deteriorated the sensory quality of the cake. These results suggest that the most suitable amount of added S. crispa powder for preparing yellow layer cake was 2% in Baker's percentage.

• Analytical Science and Technology
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• v.15 no.1
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• pp.72-79
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• 2002

Di-(2-ethylhexyl)phthalate (DEHP) may be released from plasticized poly(vinyl chloride) (PVC) articles. In the cases of various methods for the quantitative analysis of migrating DEHP, there are much differences in migrating quantity according to the experimental methods. It is therefore important to make the comparison and analysis between these two results. A study of DEHP migration from blood and infusion bags has been carried out in different methods to evaluate the amount of DEHP migration using gas chromatograph and UV-vis spectrophotometry. Five PVC bags were cut into plane sheets in size of $40{\times}10{\times}0.4mm$, then were immersed in extraction solvent for an hour to release DEHP. It was determined by a gas chromatograph that $23.2{\sim}70.9{\mu}g/mL$ of DEHP was extracted. While extraction solvent was injected into PVC bags which were then placed for an hour to leach DEHP out. It was checked by a UV-vis spectrophotometer that the concentration of DEHP in extraction solvent was $24.8{\sim}41.3{\mu}g/mL$. Two results show different values according to the extraction conditions and experimental methods and the gas chromatographic results were converted into UV-vis spectroscopic results on condition that DEHP would be extracted equally per unit time and unit contact area. It was concluded that DEHP migrating amounts are approximately equal in two analytical methods.

• Journal of the Korean Applied Science and Technology
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• v.29 no.3
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• pp.402-411
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• 2012

Natural Bokbunja is used as a material of oriental medicine which it obtains from Rubus or Raspberry. Natural Bokbunja Rubus has natural odor and taste, natural color, and pharmaceutical & chemical characteristics. This experiment tested antimicrobial experiment against microbe and dye experiment against fiber using natural Bokbunja extract. Some conclusions from this characteristics experiment were obtained as follow. The result of antimicrobial experiment could know that ATCC-001(staphylococcus aureus) does not show nearly from 72hrs after cultivation test and ATCC-002(aspergillus niger) shows to propagate continuously according to passage of time. Also, the result of dye experiment could know that cotton and silk using alum mordant($Al_2(SO_4)_3{\cdot}13-14H_2O$) against fiber shows in direction of light beige color. The result of instrument analysis ascertained inorganic components of K(221.100ppm), Mg(17.920ppm), Ca(5.129ppm), Na(2.940ppm), Si(0.638ppm) etc from Bokbunja with ICP/OES, and ascertained organic components of boric acic(1.711), silane(2.142), pyrazole(3.481), propyl isothiocyanate(2.565), furfurole(11.521) etc from Bokbunja with GC/MSD.

• Journal of Adhesion and Interface
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• v.21 no.3
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• pp.81-85
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• 2020

Shaving dust is a collagen fiber that is the leather waste occurred for thickness adjustment during the natural leather manufacturing process, and causes problems such as an environmental contamination because of a chromium (Cr) contained when it comes to reclaiming process. Various studies applying the shaving dust are currently being conducted in many countries across the world with an initiative by the EU. Of those applications, the bonded leather is being highlighted as a substitute for natural leather. Since the bonded leather, however, uses latex as a binder, accordingly it entails a high weight and a poor ventilation, which are deemed as disadvantages due to its dense internal tissues compared to other synthetic leathers. To address such disadvantages, this study employed the thermally expandable micro sphere to improve its air permeability and light weight by alleviating the internal structure. This is a study on the manufacturing of light bonded leather using the shaving dusts. In the study, the shaving dusts were forced to foam under 100~120℃ considering the heat resistance of collagen fiber after applying the thermally expandable micro sphere, and then the tendency was analyzed. In the analysis results, the most excellent foaming rate was exhibited when the shaving dusts were treated under 120℃ for 8 minutes and the variation of internal structure according to a foaming was observed through SEM analysis for the cross-section of the bonded leather.

• Journal of Korean Society of Steel Construction
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• v.28 no.1
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• pp.23-34
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• 2016

Concrete filled steel tube system has two major advantages. First, the confinement effect of steel tube improves the compressive strength of concrete. Second, the load capacity and deformation capacity of members are improved because concrete restrains local buckling of steel tube. It does, however, involve workability problem of using stud bolts or anchor bolts to provide composite effect for larger cross-sections. While the ribs inside the columns are desirable in terms of compressive behavior, they cause the deterioration in load capacity upon in-plane deformation resulting from thermal deformation. Since the ribs are directly connected with the concrete, the deformation of the ribs accelerates concrete cracking. Thus, it is required to improve the toughness of the concrete to resist the deformation of the ribs. Welding built-up tubular square columns can secure safety in terms of fire resistance if the problem are solved. This study focuses on mixing steel fiber in the concrete to improve the ductility and toughness of the columns. In order to evaluate fire resistance performance, loaded heating test was conducted with 8 specimens. The behavior and thermal deformation capacity of the specimens were analyzed for major variables including load ratio. The reliability of heat transfer and thermal stress analysis model was verified through the comparison of the results between the test and previous study.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.6
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• pp.871-879
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• 2014

Two experiments were conducted to determine the digestible energy (DE) and metabolizable energy (ME) contents of corn gluten feed (CGF) for finishing pigs and to develop equations predicting the DE and ME content from the chemical composition of the CGF samples, as well as validate the accuracy of the prediction equations. In Exp. 1, ten CGF samples from seven provinces of China were collected and fed to 66 finishing barrows (Duroc${\times}$Landrace${\times}$Yorkshire) with an initial body weight (BW) of $51.9{\pm}5.5$ kg. The pigs were assigned to 11 diets comprising one basal diet and 10 CGF test diets with six pigs fed each diet. The basal diet contained corn (76%), dehulled soybean meal (21%) and premix (3%). The ten test diets were formulated by substituting 25% of the corn and dehulled soybean meal with CGF and contained corn (57%), dehulled soybean meal (15.75%), CGF (24.25%) and premix (3%). In Exp. 2, two additional CGF sources were collected as validation samples to test the accuracy of the prediction equations. In this experiment, 18 barrows (Duroc${\times}$Landrace${\times}$Yorkshire) with an initial BW of $61.1{\pm}4.0$ kg were randomly allotted to be fed either the basal diet or two CGF containing diets which had a similar composition as used in Exp. 1. The DE and ME of CGF ranged from 10.37 to 12.85 MJ/kg of dry matter (DM) and 9.53 to 12.49 MJ/kg of DM, respectively. Through stepwise regression analysis, several prediction equations of DE and ME were generated. The best fit equations were: DE, MJ/kg of DM = 18.30-0.13 neutral detergent fiber-0.22 ether extract, with $R^2$ = 0.95, residual standard deviation (RSD) = 0.21 and p<0.01; and ME, MJ/kg of DM = 12.82+0.11 Starch-0.26 acid detergent fiber, with $R^2$ = 0.94, RSD = 0.20 and p<0.01. These results indicate that the DE and ME content of CGF varied substantially but the DE and ME for finishing pigs can be accurately predicted from equations based on nutritional analysis.

• Composites Research
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• v.25 no.4
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• pp.98-104
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• 2012

In recent years, degenerative spinal instability has been effectively treated with a cage. However, little attention is focused on the stiffness of the cage. Recent advances in the medical implant industry have resulted in the use of medical carbon fiber reinforced polymer (CFRP) cages. The biomechanical advantages of using different cage material in terms of stability and stresses in bone graft are not fully understood. A previously validated three-dimensional, nonlinear finite element model of an intact L2-L5 segment was modified to simulate posterior interbody fusion cages made of CFRP and titanium at the L4-L5 disc with pedicle screw, to investigate the effect of cage stiffness on the biomechanics of the fused segment in the lumbar region. From the results, it could be found that the use of a CFRP cage would not only reduce stress shielding, but it might also have led to increased bony fusion.