• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.324-329
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• 1999

This study is performed to evaluate an elastic properties of rice straw ash concrete . The following conclusions are drawn ; The ultrasonic pulse velocity is in the range of 4.084 ∼4.336㎧, which has showed abuot the same compared to that of the normal cement concrete. The highest ultrasonic pulse velocity is showed by 5% rice straw ash filled reice straw ash concrete. The dynamic and static modulus of elasticity i sin the range of 294 ${\times}$103 ∼ 347 ${\times}$103 and 266${\times}$ 103 ∼347${\times}$ 103 kgf/$\textrm{cm}^2$ , respectively. It is showed about the same compared to that of the normla cement concrete. The poisson's number of rice straw ash concrete is less than that of the normal cement concrete . The stress-strain curve of concrete which is contained rice straw ash within 10% appear slowly and over 10% appear almost straightly.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.3
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• pp.107-113
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• 2000

This study is performed to examine the physical and mechanical properties of concrete with fly ash. Test results show that the unit weights of concrete with fly ash are decreased 1-3% and the highest strength is achieved by 10% filled fly ash concrete with it is increased 7% than that of the normal cement concrete. the ultrasonic pulse velocity is in the range of 3.705~4.204m/s and the dynamic and static modulus of elasticity is in the range of 271$\times$103 ~289$\times$103kgf/cm2 and 208$\times$103 ~262$\times$103kgf/cm2 respectively. The acid-resistance is increased with increase of the content of fly ash. It is 1.2 times of the normal cement concrete by 10% filled fly ash concrete and 1.7 times by 30% filled fly ash concrete respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.281-284
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• 2004

The most important reason of using of ultra high strength concrete in super tall building is that ultra high strength concrete can reduce the section of members and control side sway effectively. However, the practical utilization of ultra high strength concrete is dependent not only on the production techniques, but also the overall preparation including proper code provisions, construction technique. The purpose of this study is to evaluate of mechanical properties of UHSC, such as modulus of elasticity, stress-strain behavior, modulus of rupture and tensile splitting strength. It is similar to normal or high strength concrete but necessary to discern the difference between normal or high strength concrete and ultra high strength concrete and modify existed equations. And in this study another important factor is to discern the difference according to member size, curing method in ultra high strength concrete experimentally.

• Advances in nano research
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• v.16 no.3
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• pp.303-311
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• 2024

This paper conducts a thorough economic evaluation of integrating nanoparticles into concrete structures within the construction industry, aiming to elevate the material properties of concrete. Employing the Halpin-Tsai micromechanics theory for deriving the effective material properties of the nanocomposite concrete structure, the research investigates the nuanced impact of nanoparticles on various mechanical properties, including the modulus of elasticity, compressive strength, and their indirect effects on the percentage of reinforcement. Implementing the Euler theory to formulate the governing equation based on Hamilton's principle, the study delves into the pricing dynamics of nanoparticles and their influence on the overall cost structure of concrete structures. Notably, the findings reveal that a measured increase in the volume percentage of nanoparticles, up to 1%, results in a remarkable 78% improvement in elastic modulus and a substantial 142% reduction in armature percentage. Remarkably, from an economic perspective, the incremental cost associated with the integration of nanoparticles is relatively modest (around $1 per ton of concrete), considering the substantial enhancements in mechanical properties achieved.

• Review of Culture and Economy
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• v.19 no.2
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• pp.29-50
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• 2016

This paper is to apply an individual travel cost method(TCM) to estimate demand functions for cultural services enjoyed by visiting 3 branches of the National Museum of Modern and Contemporary Art located in the Seoul Metropolitan area. This paper extends the standard TCM by incorporating opportunity costs of leisure time and two different data generating process - 398 respondents from an on-site survey and 600 respondents from a general household survey. Negative binomial models reflecting the non-negative integer nature of visiting frequency with over-dispersed variance were best fitted for demand functions, in which residents of Seoul metropolitan area surveyed from on the site exhibited higher visitation demand for the national art museum. Price elasticity and income elasticity differed by respondents' residency. Price elasticity of long distance visitors (-0.21) was more inelastic from those of Seoul residents (-0.34 ~ -0.5). Moreover, regional residents outside of Seoul area seemed to consider that services from the national art museum is a normal good with income elasticity of 0.5, whereas the Seoul residents seemed to perceive it to be an inferior good with income elasticity of -0.05.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.2
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• pp.169-176
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• 2023

In this study, stem cells were extracted from the callus derived from the aloe cambium, and the antioxidant activity and effect of skin elasticity improvement were assessed. The aloe cambium-derived stem cell extract, AloStem and callus showed the survival rate of each 98.27% and 71.31%. In the results of the DPPH antioxidant activity of AloStem and aloe extract, it was confirmed that the antioxidant effect of AloStem was more than twice that of Aloe extract. AloStem did not affect the cytotoxicity of normal human dermal fibroblasts (NHDF) cells up to 0.25% concentration. Also, AloStem increased elastin, COL1A1 and HAS2 mRNA expression levels dose-dependently. Furthermore, to examine lifting effect of skin elasticity using a sheet mask containing AloStem, 21 adult men and women applied the sheet mask in the face, once a day for 2 weeks. As a result, after 2 weeks the skin length was 116.75 ± 5.58 mm before the use of the sheet mask, but after 2 weeks of use, it was confirmed that 0.59% increased to 117.44 ± 5.17 mm. Thus, we concluded that the sheet mask containing AloStem can help the lifting effect of skin elasticity.

• The Journal of Internal Korean Medicine
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• v.28 no.3
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• pp.544-559
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• 2007

Objectives : This study was designed to evaluate the anti-diabetes and vasoelasticity effects of Mori Folium and Aurantii Fructus in streptozotocin-induced type II diabetes mellitus model. Methods : The anti-diabetic effect of Mori Folium and Aurantii Fructus on rats induced with diabetes by streptozotocin was investigated through analyses of changes in body weight, blood glucose, urine volume of rats, viability of human umbilical vein endothelial cells(HUVECs), and elasticity of descending thoracic aorta in rats. The subjects in this study were divided into four groups(n=15): a normal group without any treatment (Con), a normal group with Mori Folium and Aurantii Fructus treatment(Con+P), a diabetes group induced by streptozotocin(STZ), and a Mori Folium and Aurantii Fructus treatment group under diabetes induced by streptozotocin(STZ+P). Rats were administered streptozotocin to induce diabetes. Results : The study showed that Mori Folium and Aurantii Fructus significantly reduced highly increased blood glucose levels(p<0.01) and prevented the diabetic rats from weight loss(p<0.01) and polyurea(p<0.05), Mori Folium and Aurantii Fructus also recovered decreased viability of HUVECs(p<0.01) and damaged elasticity of aorta induced by the streptozotocin (p<0.01). Conclusions: It was concluded from the results that Mori Folium and Aurantii Fructus have a distinct anti-diabetes effect and they also prevent damage of blood vessel induced by diabetes. resulting in prevention of cardiovascular diseases ascribed to diabetes.

• Archives of Craniofacial Surgery
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• v.15 no.1
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• pp.14-21
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• 2014

Background: There are several options for replacement of the dermal layer in fullthickness skin defects. In this study, we present the surgical outcomes of reconstruction using acellular dermal substitutes by means of objective and subjective scar assessment tools. Methods: We retrospectively reviewed the medical records of 78 patients who had undergone autologous split-thickness skin graft with or without concomitant acellular dermal matrix (CGDerm or AlloDerm) graft. We examined graft survival rate and evaluated postoperative functional skin values. Individual comparisons were performed between the area of skin graft and the surrounding normal skin. Nine months after surgery, we compared the skin qualities of CGDerm graft group (n=25), AlloDerm graft group (n=8) with skin graft only group (n=23) each other using the objective and subjective measurements. Results: The average of graft survival rate was 93% for CGDerm group, 92% for AlloDerm group and 86% for skin graft only group. Comparing CGDerm grafted skin to the surrounding normal skin, mean elasticity, hydration, and skin barrier values were 87%, 86%, and 82%, respectively. AlloDerm grafted skin values were 84%, 85%, and 84%, respectively. There were no statistical differences between the CGDerm and AlloDerm groups with regard to graft survival rate and skin functional analysis values. However, both groups showed more improvement of skin quality than skin graft only group. Conclusion: The new dermal substitute (CGDerm) demonstrated comparable results with regard to elasticity, humidification, and skin barrier effect when compared with conventional dermal substitute (AlloDerm).

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.6
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• pp.83-95
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• 1996

The normal cement concrete is widely used material to build the construction recently, but it has a fault to increase the dead load on account of its unit weight is large compared with strength. So, main purpose of this study was to establish the physical and mechanical properties of lightweight concrete using expanded polystyrene bead on fine aggregate and natural gravel, expanded clay and pumice stone on coarse aggregate. The test rusults of this study are summarized as follows; 1. The water-cement ratio of concrete using pumice stone was larger than that of the concrete using natural gravel and expanded clay. 2. The unit weights of concrete using pumice stone and expanded caly were shown less than 1,000g/$m^3$. 3. The compressive strengths of all types were shown less than 60kg/$cm^2$, tensile and bending strengths were shown less than l3kg/$cm^2$ and 3lkg/$cm^2$$^2$, respectively. 4. The pulse velocity of concrete was shown similar with using natural gravel and pumice stone, and shown the lowest using pumice stone. 5. The dynamic modulus of elasticity of concrete was shown considerably smaller, and shown the lowest using pumice stone. 6. The static modulus of elasticity of concrete using expanded clay and pumice stone were shown considerably smaller, and shown 22% ~29% as compared with the dynamic modulus of elasticity. 7. The stress-strain curves of concrete were shown similar, generally. And the curves were repeated at short intervals increase and decreased irregularly.

• Journal of Oral Medicine and Pain
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• v.32 no.4
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• pp.421-429
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• 2007

Some researchers suggested that tactile sensor system would be useful in evaluating masticatory muscles of TMD patients, but there were few studies on the effects of chewing with time. The aim of this study was to investigate the change of elasticity and stiffness for masseter and temporal muscles of normal subjects before, during and after gum chewing and to obtain the baseline data for further researches on the elasticity and stiffness for masticatory muscles of TMD patients. Stiffness and elasticity of their anterior temporalis and inferior masseter muscle were measured bilaterally by a tactile sensor system. Each subject was instructed to sit on a chair for evaluation of masticatory muscles. Before operating the sensor, the thickest skin area over anterior temporalis and inferior masseter muscles were selected as the points to be pressed by a tactile sensor, and marked with a pen. While the teeth of subjects were lightly contacted, the probe of the tactile sensor was placed perpendicularly over the marked point over the skin, followed by computer-controlled movement including gently pressing straight down on the muscle for a second and retracting. All subjects were instructed to chew gum (Excellent Breath, Taiyo Co., Japan) bilaterally with a velocity of 2 times per second for 40 minutes after the first measurement had been performed for the baseline data of all subjects. The measurements had been repeated during chewing with 10 minutes of interval and continued for 40 minutes with same interval after chewing. Resultantly, the decrease of elasticity and the increase of stiffness in masticatory muscles can be seen significantly within 10 minutes after chewing and those were maintained during chewing without significant change with chewing time. The elasticity of muscles was recovered within 10 minutes after stopping chewing, but the stiffness was recovered more lately than elasticity by about 10 minutes. Based on these results, it can be concluded that elasticity and stiffness of muscles would be good indicators to evaluate the masticatory muscles objectively, when more supported by further researches.