• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.4
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• pp.220-230
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• 2006

Fracture behavior of a monolithic PZT and a plate-type piezoelectric composite actuator (PCA) has been investigated under a bending load at three points by an acoustic emission (AE) monitoring. AE signal from a monolithic PZT at the maximum bending load shows the characteristics of high amplitude and long duration with a low frequency band of $100{\sim}230kHz$ which is confirmed by fast Fourier transform (FFT). For a PCA, it is concluded that AE signals with high amplitude over 80dB and low dominant frequency band of $170{\sim}223kHz$ emitted in the stage I are due to the brittle fracture in the PZT layer and the delamination between the PZT layer and the adjacent fiber composite layer. Based on the above analysis of AE behavior and damage observations with an optical microscopy and a scanning electron microscopy, AE characteristics related to fracture behavior of asymmetrically laminated PCA have been elucidated.

• Textile Coloration and Finishing
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• v.8 no.3
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• pp.8-15
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• 1996

Three pieces of cotton fabrics used for this study were exhumed in the Mt.Moo Deung near Kwang Ju in 1965. The fabrics were remains of Jang Heung Lim Si-the nephew's wife of General Kim Deok Ryeong. It was reported that Jang Heung Lim Si died in 1615. The cotton fabrics were classified into three, A, B and C, according to their color. The fabric A was inherent color of cotton, the fabric B was that of light brown and the fabric C was that of dark brown. The physical and chemical characteristics of the cotton fabrics were examined. In the meantime the construction of cotton fabrics and traditional dyeing of Yi dynasty were studied through various records. The results were as follows: 1. According to electromicroscopic examination, the lumen in the cotton fiber had not been developed enough, therefore the quality of cotton at that time was supposed to be not so excellent. 2. The results of chemical analysis indicated that: (1) While the copper number of the cotton fabric A was similar to that of bleached cotton, that of the fabric C was extremely high. (2) The amount of methylene blue absorption was much more than that of normal cotton. (3) The content of cellulose was less than that of normal cotton. (4) The degree of polymerization was less than that of normal cotton. From the results mentioned above, it was concluded that the cotton fabrics were oxidized slowly in the closed lime coffin for a long period of time. From this process of oxidization and deterioration, the degree of polymerization was decreased through depolymerization, and carboxyl groups were produced by the oxidization at reducing end groups. 3. It was confirmed that the cotton fabric C was dyed by the juice of immature persimmon. Thus, it was inferred that the large amount of copper number of cotton fabric C was derived from phenolic OH groups of tannins having high reducing properties in persimmon.

• Journal of Nutrition and Health
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• v.45 no.5
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• pp.462-469
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• 2012

We investigated dietary effects of prickly pear cactus (Opuntina ficus-indica) on plasma lipids, platelet aggregation (PA), hemolysis, plasma TBARS and liver enzymes. Twenty eight volunteer diving women in Jeju island had daily 20 g cactus tea containing 27% prickly pear cactus (PPC) powder for 4 weeks, and data for the study subjects were analyzed, on the basis of diagnostic criteria for blood pressure (BP)(${\geq}$ 140/90 mmHg), plasma cholesterol (${\geq}$ 200 mg/dL) and triglyceride (${\geq}$ 150 mg/dL). The subjects with higher BP had higher plasma total cholesterol (TC) and triglyceride (TG) concentrations than those with normal BP. Those with higher TC also had higher TG. Subjects with normal BP or normal TC had higher initial slope of PA than their higher counterpart in BP and TC. PPC intake decreased plasma TG in those with higher BP. PPC intake significantly decreased the elevated initial slope in groups with normal BP, TC, and TG. Hemolysis after PPC intake decreased significantly in all the subjects and plasma TBARS decreased in the subjects with higher plasma TC and higher TG. Glutamic-oxaloacetic transaminase (GOT) significantly increased and total bilirubin significantly decreased in all the subjects after PPC intake. The present study with diving women showed that beneficial effects of short term intake of prickly pear cactus might differ depending on the subject conditions in term of blood pressure, and plasma lipids. However, long term usage of prickly pear cactus may provide preventive effects of cardiovascular diseases to all the population, presumably by hypolipidemic, antithrombotic, and antioxidant actions of its bioactive flavonoids and soluble fiber.

• Journal of Nutrition and Health
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• v.50 no.3
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• pp.203-216
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• 2017

Purpose: This literature review was performed to assess the effect of raisins on human health. Methods: A review of Medline was conducted using the keywords: 'raisins, raisins and health, raisins and cardiovascular disease (CVD), raisins and cancer, raisins and diabetes, raisins and fiber, raisins and colon health, raisins and antioxidants, raisins and inflammation, raisins and dental caries'. The reference lists from previous review articles on raisins and human health and the California Raisin Marketing Board files were reviewed for additional studies. Results: Raisins have one of the highest polyphenolic content and antioxidant ORAC levels compared to other traditional dried fruits. Many of the polyphenols in raisins are well assimilated and bioavailable. Raisin consumption reduces low density lipoprotein (LDL) cholesterol, blood pressure and blood sugar, when compared to equal caloric carbohydrate snacks and is associated with a reduced risk of CVD. The anti-inflammatory and cancer chemopreventive effects of raisins are mixed. Raisin consumption reduces intestinal transit time and positively affects gut microbiota. Raisins produce sustained energy during long term athletic competitions equal to traditional sports energy gels, shots and jelly beans. Raisins produce a non-cariogenic oral environment and do not fit the American Academy of Pediatrics criteria to be considered a choking hazard. Conclusions: Based on the review of literature, consumption of raisins provide numerous health benefits for promoting general wellness and in the prevention of many chronic diseases including: CVD, type 2 diabetes mellitus (T2DM) gastrointestinal diseases, and dental caries.

• Steel and Composite Structures
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• v.29 no.4
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• pp.527-544
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• 2018

The paper presents the study on a change in modal parameters and structural stiffness of cable-stayed Fiberline Bridge made entirely of Glass Fiber Reinforced Polymer (GFRP) composite used for 20 years in the fjord area of Kolding, Denmark. Due to this specific location the bridge structure was subjected to natural aging in harsh environmental conditions. The flexural properties of the pultruded GFRP profiles acquired from the analyzed footbridge in 1997 and 2012 were determined through three-point bending tests. It was found that the Young's modulus increased by approximately 9%. Moreover, the influence of the temperature on the storage and loss modulus of GFRP material acquired from the Fiberline Bridge was studied by the dynamic mechanical analysis. The good thermal stability in potential real temperatures was found. The natural vibration frequencies and mode shapes of the bridge for its original state were evaluated through the application of the Finite Element (FE) method. The initial FE model was created using the real geometrical and material data obtained from both the design data and flexural test results performed in 1997 for the intact composite GFRP material. Full scale experimental investigations of the free-decay response under human jumping for the experimental state were carried out applying accelerometers. Seven natural frequencies, corresponding mode shapes and damping ratios were identified. The numerical and experimental results were compared. Based on the difference in the fundamental natural frequency it was again confirmed that the structural stiffness of the bridge increased by about 9% after 20 years of service life. Data collected from this study were used to validate the assumed FE model. It can be concluded that the updated FE model accurately reproduces the dynamic behavior of the bridge and can be used as a proper baseline model for the long-term monitoring to evaluate the overall structural response under service loads. The obtained results provided a relevant data for the structural health monitoring of all-GFRP bridge.

• Polymer(Korea)
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• v.34 no.4
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• pp.321-325
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• 2010

Fibroin is a biopolymer available in large quantity from silk fiber and has a long history of use as a suture proving biocompatibility. In this report, fibroin microspheres has been fabricated for biomaterial applications. W/O emulsion of regenerated fibroin droplets in a continuous phase of decane with mixed surfactants was dried to facilitate fibroin gelation and the condensed fibroin microspheres were harvested. The ratio of mixed surfactants and their proportions to decane were determined to prepare a stable W/O emulsion. A spherical form of fibroin gels was obtained from the W/O emulsion agitated at 600 rpm. Scanning electron microscopy revealed that number average sizes of the fibroin microspheres were 21.6 and 8.5 ${\mu}m$ when dried under ambient conditions or under vacuum, respectively. Tomography of the spheres revealed that their internal structures are packed or hollowed. Hollow and hemispherical forms of microspheres were also prepared by using porogen.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.641-659
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• 2010

Structural Health Monitoring (SHM) gradually becomes a technique for ensuring the health and safety of civil infrastructures and is also an important approach for the research of the damage accumulation and disaster evolving characteristics of civil infrastructures. It is attracting prodigious research interests and the active development interests of scientists and engineers because a great number of civil infrastructures are planned and built every year in mainland China. In a SHM system the sheer number of accompanying wires, fiber optic cables, and other physical transmission medium is usually prohibitive, particularly for such structures as offshore platforms and long-span structures. Fortunately, with recent advances in technologies in sensing, wireless communication, and micro electro mechanical systems (MEMS), wireless sensor technique has been developing rapidly and is being used gradually in the SHM of civil engineering structures. In this paper, some recent advances in the research, development, and implementation of wireless sensors for the SHM of civil infrastructures in mainland China, especially in Dalian University of Technology (DUT) and Harbin Institute of Technology (HIT), are introduced. Firstly, a kind of wireless digital acceleration sensors for structural global monitoring is designed and validated in an offshore structure model. Secondly, wireless inclination sensor systems based on Frequency-hopping techniques are developed and applied successfully to swing monitoring of large-scale hook structures. Thirdly, wireless acquisition systems integrating with different sensing materials, such as Polyvinylidene Fluoride(PVDF), strain gauge, piezoresistive stress/strain sensors fabricated by using the nickel powder-filled cement-based composite, are proposed for structural local monitoring, and validating the characteristics of the above materials. Finally, solutions to the key problem of finite energy for wireless sensors networks are discussed, with future works also being introduced, for example, the wireless sensor networks powered by corrosion signal for corrosion monitoring and rapid diagnosis for large structures.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.595-618
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• 2010

This paper describes the application of a wireless sensor network to a 31 meter-tall medieval tower located in the city of Trento, Italy. The effort is motivated by preservation of the integrity of a set of frescoes decorating the room on the second floor, representing one of most important International Gothic artworks in Europe. The specific application demanded development of customized hardware and software. The wireless module selected as the core platform allows reliable wireless communication at low cost with a long service life. Sensors include accelerometers, deformation gauges, and thermometers. A multi-hop data collection protocol was applied in the software to improve the system's flexibility and scalability. The system has been operating since September 2008, and in recent months the data loss ratio was estimated as less than 0.01%. The data acquired so far are in agreement with the prediction resulting a priori from the 3-dimensional FEM. Based on these data a Bayesian updating procedure is employed to real-time estimate the probability of abnormal condition states. This first period of operation demonstrated the stability and reliability of the system, and its ability to recognize any possible occurrence of abnormal conditions that could jeopardize the integrity of the frescos.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.12
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• pp.149-156
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• 2019

Recently, skyscraper building and apartment fires, which were rapidly spread out from a low floor to a rooftop, have become a frequent occurrence in mass media. This fire problems have a fatal disadvantage that the exterior wall finish of the building emits toxic gas in case of fire by using dry bit method or organic insulating material. Therefore, in order to remedy these problems, many exterior wall finishing construction methods have been proposed, but the current trend is to use existing construction methods due to problems such as economy, weight, and durability. On the other hand, in countries such as Germany and Japan, ceramic sidings are used as exterior finishing material for buildings, which is environmentally friendly, excellent natural beauty, long life, easy maintenance and high-quality exterior materials. However, those ceramic sidings have still the problems such as manufacturing cost and weight problem because of boosting the sintering temperature up to 1,350℃ or more. Also, conventional CRC, MgO, FRP sidings which are composed of pulp, glass fiber and organic materials, have been reports of deformation due to ultraviolet rays, discoloration, corrosion and scattering, surface rupture, lifting and peeling. Therefore, in this study as an alternative to solve this problem, halosite nano kaolin produced in Sancheong in Korea and frit flux were used to satisfy the required properties as ceramic siding using low temperature sintering (below 1,000℃) and lightweight materials such as pearlite. This study aims to design the optimal formulation and process of materials and to study the characteristics of nano-coated ceramic siding material development and to present relevant basic data. The findings show that ceramic siding for nanocoated building materials is excellent as a natural ceramic siding building material. The fire resistance of natural minerals and nano particle refining technology satisfy the bending strength of 80kgf / cm2, the volume ratio of 2.0 and the absorption rate of less than 10.0%.

• Journal of Veterinary Science
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• v.19 no.6
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• pp.750-758
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• 2018

Influenza virus infection is a zoonosis that has great socioeconomic effects worldwide. Influenza infection induces respiratory symptoms, while the influenza virus can infect brain and leave central nervous system sequelae. As children are more vulnerable to infection, they are at risk of long-term neurological effects once their brains are infected. We previously demonstrated that functional changes in hippocampal neurons were observed in mice recovered from neonatal influenza infection. In this study, we investigated changes in myelination properties that could affect neural dysfunction. Mice were infected with the influenza virus on postnatal day 5. Tissues were harvested from recovered mice 21-days post-infection. The expression levels for myelin basic protein (MBP) were determined, and immunohistochemical staining and transmission electron microscopy were performed. Real-time polymerase chain reaction and Western blot analyses showed that mRNA and protein expressions increased in the hippocampus and cerebellum of recovered mice. Increased MBP-staining signal was observed in the recovered mouse brain. By calculating the relative thickness of myelin sheath in relation to nerve fiber diameter (G-ratio) from electron photomicrographs, an increased G-ratio was observed in both the hippocampus and cerebellum of recovered mice. Influenza infection in oligodendrocyte-enriched primary brain cell cultures showed that proinflammatory cytokines may induce MBP upregulation. These results suggested that increased MBP expression could be a compensatory change related to hypomyelination, which may underlie neural dysfunction in recovered mice. In summary, the present results demonstrate that influenza infection during the neonatal period affects myelination and further induces functional changes in influenza-recovered mouse brain.