• Advances in nano research
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• v.16 no.6
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• pp.565-577
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• 2024

Vibration investigation of fluid-filled functionally graded cylindrical shells with ring supports is studied here. Shell motion equations are framed first order shell theory due to Sander. These equations are partial differential equations which are usually solved by approximate technique. Robust and efficient techniques are favored to get precise results. Employment of the Rayleigh-Ritz procedure gives birth to the shell frequency equation. Use of acoustic wave equation is done to incorporate the sound pressure produced in a fluid. Hankel's functions of second kind designate the fluid influence. Mathematically the integral form of the Langrange energy functional is converted into a set of three partial differential equations. A cylindrical shell is immersed in a fluid which is a non-viscous one. These shells are stiffened by rings in the tangential direction. For isotropic materials, the physical properties are same everywhere where the laminated and functionally graded materials, they vary from point to point. Here the shell material has been taken as functionally graded material. After these, ring supports are located at various positions along the axial direction round the shell circumferential direction. The influence of the ring supports is investigated at various positions. Effect of ring supports with empty and fluid-filled shell is presented using the Rayleigh - Ritz method with simply supported condition. The frequency behavior is investigated with empty and fluid-filled cylindrical shell with ring supports versus circumferential wave number and axial wave number. Also the variations have been plotted against the locations of ring supports for length-to-radius and height-to-radius ratio. Moreover, frequency pattern is found for the various position of ring supports for empty and fluid-filled cylindrical shell. The frequency first increases and gain maximum value in the midway of the shell length and then lowers down. It is found that due to inducting the fluid term frequency result down than that of empty cylinder. It is also exhibited that the effect of frequencies is investigated by varying the surfaces with stainless steel and nickel as a constituent material. To generate the fundamental natural frequencies and for better accuracy and effectiveness, the computer software MATLAB is used.

• Journal of Applied Biological Chemistry
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• v.58 no.2
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• pp.145-151
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• 2015

Corn fiber protein (CFP) was extracted from corn wet-milling by-product, corn fiber. CFP films containing various plasticizers and cross-linking agents were prepared and their mechanical properties were determined. Among the plasticizers and cross-linking agents used in this study, the CFP film containing 2 g fructose and 0.03% cinnamaldehyde had the most appropriate physical property. In addition, the CFP films containing green tea extract (GTE) were prepared by incorporating different amounts (0, 0.5, 1.0, 1.5%) of GTE into the film-forming solution. Tensile strength, film solubility, and opacity of the CFP films increased with the addition of GTE, whereas elongation and water vapor permeability of the CFP/GTE films decreased compared to those of the control. The antioxidant activity of the CFP/GTE film was determined in terms of 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity. As a result, antioxidant activity of the films increased with increasing GTE concentration. Furthermore, antimicrobial activity against Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus increased with increasing GTE concentration. These results indicate that the incorporation of GTE could enhance antioxidant and antimicrobial activities of the CFP films.

• The Journal of the Korea Contents Association
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• v.10 no.5
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• pp.416-421
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• 2010

The KISTI (Korea Institute of Science and Technology Information) began to produce the Korean human information called Visible Korean and Digital Korean since 2000 because there was no human information in Korea which could represent the physical characteristics of Korean human body. The Visible Korean consists of CT, MR, sectioned and segmented images of Korean human body. We obtained the serially sectioned images by grinding the Korean cadaver in horizontal direction and segmented these images by outlining the inner organs of human. We have produced the sectioned images of Korean male whole body, male head, and female pelvis in2008. The segmentation and 3D reconstruction of these images are now in proceeding. The Digital Korean consists of CT images of about 100 Korean cadavers. These CT images were segmented by individual bone, reconstructed to produce the 3D bone models and the skin surface model was also added. The mechanical properties of individual bones were obtained by measuring the property of individual bone sample. We have distributed these Korean human informations to users in domestic and abroad. About 70 institutes in domestic, and 20 institutes in abroad have used our data in research use and nearly 160 proceedings and articles were published since 2001. We think these human informations have a role of medical information infrastructure that could be used in the field of medical education, biomechanics, virtual reality etc.

• Korean journal of food and cookery science
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• v.26 no.6
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• pp.707-716
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• 2010

Germinated brown rice is a useful material that contains natural nutrients and biologically active substances. This study was conducted to develop a optimal composite recipe for functional germinated brown rice cookie with added spinach (spinacia oleracea L) powder and with high preference in all age groups. The experimental design utilized herein was based on the Central composite design methodology of response surface, which included 16 experimental points, including 2 replicates for spinach, sugar, and butter. The physical, mechanical, and sensory properties of the test were measured, and these values were applied to the mathematical models. A canonical form and perturbation plot showed the influence of each ingredient on the mixed final product. The results of spread ratio decreased significantly with increases in spinach powder, sugar, and butter(p<0.01). L value shows that lightness decreased significantly with an increase in sugar(p<0.05), but the a and b values were not significant. Sensory evaluation found significant values for color(p<0.05), flavor(p<0.05), texture(p<0.05) and overall quality(p<0.05) in the predicted model. The optimum formulation by the numerical and graphical methods was calculated as follows: spinach powder 3 g, sugar 35.5 g butter 54.4 g.

• Membrane Journal
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• v.31 no.6
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• pp.371-383
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• 2021

Anion exchange membranes have been used for water electrolysis, which can produce hydrogen, and fuel cells, which can generate electrical energy using hydrogen fuel. Anion exchange membranes operate based on hydroxide ion (OH^-) conduction under alkaline conditions. However, since the anion exchange membrane shows relatively low ion conductivity and alkaline stability, there is still a limit to its commercialization in water electrolysis and fuel cells. To address these issues, it is important to develop novel anion exchange membrane materials by rationally designing a polymer structure. In particular, the polymer structure and synthetic method need to be controlled. By doing so, for polymers, the physical properties, ionic conductivity, and alkaline stability can be maintained. Among many anion exchange membranes, poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is commercially available and easily accessible. In addition, the PPO has relatively high mechanical and chemical stability compared to other polymers. In this review, we introduce the recent development strategy and characteristics of PPO-based polymer materials used in anion exchange membranes.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.102-108
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• 2010

The internal structure of a river embankment must be delineated as part of investigations to evaluate its safety. Geophysical methods can be most effective means for that purpose, if they are used together with geotechnical methods such as the cone penetration test (CPT) and drilling. Since the dyke body and subsoil in general consist of material with a wide range of grain size, the properties and stratification of the soil must be accurately estimated to predict the mechanical stability and water infiltration in the river embankment. The strength and water content of the levee soil are also parameters required for such prediction. These parameters are usually estimated from CPT data, drilled core samples and laboratory tests. In this study we attempt to utilise geophysical data to estimate these parameters more effectively for very long river embankments. S-wave velocity and resistivity of the levee soils obtained with geophysical surveys are used to classify the soils. The classification is based on a physical soil model, called the unconsolidated sand model. Using this model, a soil profile along the river embankment is constructed from S-wave velocity and resistivity profiles. The soil profile thus obtained has been verified by geotechnical logs, which proves its usefulness for investigation of a river embankment.

• Journal of the Korean Wood Science and Technology
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• v.45 no.6
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• pp.836-845
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• 2017

Gravimetric method is usually used to evaluate air-dry density, which is governing physical or mechanical properties of wood. Although it had high evaluation accuracy, the method is time consuming process. Thus, this study was conducted to estimate air-dry density of wood with high accuracy by using polychromatic X-ray and digital detector as alternative of gravimetric method. To quantify polychromatic X-ray projection for evaluating air-dry density, Lambert-Beer's law with the integral value of probability function was used. The integral value was used as weighting factor in the law, and it was determined by conducting simple test at various penetration depths and tube voltage. Mass attenuation coefficient (MAC) of wood also calculated by investigating polychromatic X-ray projection according to species, penetration depth and tube voltage. The species had not an effect on change of MAC. Finally, an air-dry density of wood was estimated by applying the integral value, MAC and Lambert-Beer's law to polychromatic X-ray projection. As an example, the relation of the integral value (${\alpha}$) according to penetration depth (t, cm) at tube voltage of 35 kV was ${\alpha}=-0.00091t{\times}0.0184$ while the regression of the MAC (${\mu}$, $cm^2/g$) was ${\mu}=0.5414{\exp}(-0.0734t)$. When calculation of root mean squared error (RMSE) was performed to check the estimation accuracy, RMSE at 35, 45 and 55 kV was 0.010, 0.013 and $0.009g/cm^3$, respectively. However, partial RMSE in relation to air-dry density was varied according to tube voltage. The partial RMSE below air-dry density of $0.41g/cm^3$ was $0.008g/cm^3$ when tube voltage of 35 kV was used. Meanwhile, the partial RMSE above air-dry density of $0.41g/cm^3$ decreased as tube voltage increased. It was conclude that the accuracy of estimation with polychromatic X-ray and digital detector was quite high if the integral value and MAC of wood were determined precisely or a condition of examination was chosen properly. It was seemed that the estimation of air-dry density by using polychromatic X-ray system can supplant the gravimetric method.

• Korean Journal of Food Science and Technology
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• v.45 no.2
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• pp.180-190
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• 2013

The purpose of this study was to determine the optimal amount of 2 ingredients, i.e., black barley flour ($X_1$), and olive oil ($X_2$), for the production of white pan bread from black barley flour. The experiment was designed according to the central composite design of response surface methodology, which showed 10 experimental points, including 2 replicates for black barley flour and olive oil. Significant differences were found in the results of the physical and mechanical properties analysis of each sample, including weight (p<0.05), volume (p<0.01), specific loaf volume (p<0.01), color L (p<0.01), color a (p<0.001), color b (p<0.05), hardness (p<0.001), springiness (p<0.01), cohesiveness (p<0.01), gumminess (p<0.001) and chewiness (p<0.05). Significant differences in the sensory measurements were observed in color (p<0.01), appearance (p<0.01), texture (p<0.05), taste (p<0.05) and overall quality (p<0.05). The optimum formulation, which was calculated using the numerical and graphical methods, was determined to be 18.00% black barley flour and 1.80% olive oil.

• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.698-706
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• 2019

Over the last few decades, there have been a lot of efforts to develop soft actuators, which can be external stimuli-responsive and applied to the human body. In order to fabricate medical soft actuators with a dynamic precision control, the 3D crosslinked poly(acrylic acid) (PAAc)/poly(vinyl alcohol) (PVA)/poly(ethylene glycol) (PEG) hydrogels were synthesized in this study by using a radiation technique without noxious chemical additives or initiators. After irradiation, all hydrogels showed high gel fraction over 75% and the ATR-FTIR spectra indicated that PAAc/PVA/PEG hydrogels were successfully synthesized. In addition, the gel fraction, equilibrium water content, and compressive strength were measured to determine the change in physical properties of PAAc/PVA/PEG hydrogels according to the irradiation dose and content ratio of constituents. As the irradiation dose and amount of poly(ethylene glycol) diacrylate (PEGDA) increased, the PAAc/PVA/PEG hydrogels showed a high crosslinking density and mechanical strength. It was also confirmed that PAAc/PVA/PEG hydrogels responded to electrical stimulation even at a low voltage of 3 V. The bending behavior of hydrogels under an electric field can be controlled by changing the crosslinking density, ionic group content, applied voltage, and ionic strength of swelling solution.

• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.23-27
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• 2013

The risks of debris flows caused by climate change have increased significantly around the world. Recently, landslide disaster prevention technology is more focused on the failure and post-failure dynamics to mitigate the hazards in flow-prone area. In particular, we should define the soil strength and flow characteristics to estimate the debris flow mobility in the mountainous regions in Korea. To do so, we selected known ancient landslides area: Inje, Pohang and Sangju debris flows. Firstly we measured physical and mechanical properties: liquidity index and undrained shear strength by fall cone penetrometer. From the test results, we found that there is a possible relationship between liquidity index and undrained shear strength, $C_{ur}=(1.2/I_L)^{3.3}$, in the selected areas, even though they were different in geological compositions. Assuming that the yield stress is equal to the undrained shear strength at the initiation of sliding, we examined the flow characteristics of weathered soils in Korea. When liquidity index is given as 1, 1.5 and 3.0, the debris flow motion of weathered soils is compared with that of mud-rich sediments, which are known as low-activity clays. At $I_L=1$, it seems that debris flow could reach approximately 250m after 5 minutes. As liquidity index increased from 1 to 3, the debris flow propagation of weathered soils is twice than that of low-activity clays. It may be due to the fact that soil masses mixed with the ambient water and then highly fragmented during flow, thereby leading to the high mobility. The results may help to predict the debris flow propagation and to develop disaster prevention technology at similar geological settings, especially for the weathered soils, in Korea.