• Journal of Oral Medicine and Pain
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• v.35 no.1
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• pp.49-59
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• 2010

The purpose of this study was to investigate short-term masticatory muscle reactions in response to simulated noise and music sound. Hypothesis of this study was that loud noise would cause increased stiffness and decreased elasticity of the masticatory muscles compared to low level of noise or identical sound level of music. Fifteen male volunteers were recruited for the study. The sound levels of noise and music used here were 60 dB and 100 dB. The experiment comprised 4 sessions, Session 1 with 100 dB of noise for the 1st day of experiment: Session 2 with 100 dB of music for the $2^{nd}$ day: Session 3 with 60 dB of noise for the $3^{rd}$ day: Session 4 with 60 dB of music for the $4^{th}$ day. Stiffness and elasticity on the anterior temporalis and superficial masseter muscles were measured with tactile sensor before and 2, 4 and 6 minutes after exposure of sound. The study indicated that, in short-term exposure of sound, there was no significant difference between noise and music at both 60 and 100 dB of sound level, but that there were partially significant differences between 60 and 100 dB of sound level regardless of sound type. This suggest that high level of sounds like 100 dB used in this study, in spite of short term exposure of several minutes, would lead to masticatory muscle contraction, especially in the masseter muscles.

• Korea-Australia Rheology Journal
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• v.21 no.4
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• pp.269-280
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• 2009

The drop formation dynamics of a shear thinning, elastic, yield stress ($\tau_o$) fluid (Carbopol 980 (poly(acrylic acid)) dispersions) in silicone oil has been investigated in a flow-focusing microfluidic channel. The rheological character of each solution investigated varied from Netwonian-like through to highly non-Newtonian and was varied by changing the degree of neutralization along the poly (acrylic acid) backbone. We have observed that the drop size of these non-Newtonian fluids (regardless of the degree of neutralisation) showed bimodal behaviour. At first we observed increases in drop size with increasing viscosity ratio (viscosity ratio=viscosity of dispersed phase (DP)/viscosity of continuous phase (CP)) at low flowrates of the continuous phases, and thereafter, decreasing drop sizes as the flow rate of the CP increases past a critical value. Only at the onset of pinching and during the high extensional deformation during pinch-off of a drop are any differences in the non-Newtonian characteristics of these fluids, that is extents of shear thinning, elasticity and yield stress ($\tau_o$), apparent. Changes in these break-off dynamics resulted in the observed differences in the number and size distribution of secondary drops during pinch-off for both fluid classes, Newtonian-like and non-Newtonian fluids. In the case of the Newtonian-like drops, a secondary drop was generated by the onset of necking and breakup at both ends of the filament, akin to end-pinching behavior. This pinch-off behavior was observed to be unaffected by changes in viscosity ratio, over the range explored. Meanwhile, in the case of the non-Newtonian solutions, discrete differences in behaviour were observed, believed to be attributable to each of the non-Newtonian properties of shear thinning, elasticity and yield stress. The presence of a yield stress ($\tau_o$), when coupled with slow flow rates or low viscosities of the CP, reduced the drop size compared to the Newtonian-like Carbopol dispersions of much lower viscosity. The presence of shear thinning resulted in a rapid necking event post onset, a decrease in primary droplet size and, in some cases, an increase in the rate of drop production. The presence of elasticity during the extensional flow imposed by the necking event allowed for the extended maintenance of the filament, as observed previously for dilute solutions of linear polymers during drop break-up.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.87-96
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• 1968

As the raw material of fish paste, the experiment on shark meats was conducted from July to December 1967 at the Fisheries Research and Development Agency, Pusan, Korea. The result and the conclusion obtained by the experiment are as follows. 1. Much salt-soluble protein was found in the shark meat comparing with to the other fish. 2. Deodorization of shark meat, using less than $0.05\%$ of acetic acid was most preferable for the elasticity and flexibility of its product. 3. Keeping raw material at low temperature was necessary in maintaining its elasticity. 4. In setting shark fish paste, keeping the raw material at $35-40^{\circ}C$ for 40-70 minutes was the most desirable condition. 5. The best temperature and the duration of heating were 40-60 minutes at $89-90^{\circ}C$, Meanwhile, heating at high temperature was preferable for the storage for a long period, but the elasticity and quality has decreased a little accordingly. 6. For the increase of its palatability, adding $30\%$ of yellow corvenia meat or $20\%$ sea eel meat were more preferable. 7. Pre ervation of the product for 20 days at $20^{\circ}C$ or 50 days at $5^{\circ}C$ was possible by adding $0.2\%$ potassium sorbinate to the product as antiseptic.

• Journal of Korean Medicine Rehabilitation
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• v.25 no.4
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• pp.123-137
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• 2015

Objectives The aim of this clinical study was to find out the changes of vital sign, body composition, skin status before and after combined spa-exercise therapy in participants of middle-aged women. Methods In this study 24 participants of middle-aged women went through 12 weeks of combined spa-exercise therapy. Each week vital sign, body composition, skin status were measured before exercise, which consisted of warming-up, whole body exercise and final exercises bathing in spa ($32{\sim}36^{\circ}C$). Results 1. The average of systolic blood pressure significantly decreased from $126.38{\pm}19.33mmHg$ to $120.46{\pm}11.18mmHg$ after 11 weeks of spa-exercise therapy (p<0.05). 2. The average of moisture of skin significantly increased from $36.83{\pm}3.18$ to $44.21{\pm}7.43$ after 11 weeks of spa-exercise therapy (p<0.05). 3. The average of elasticity of skin significantly increased from $59.75{\pm}3.50$ to $62.63{\pm}2.29$ after 11 weeks of spa-exercise therapy (p<0.05). 4. The average of diastolic blood pressure, pulse, et cetera. didn't significantly change after spa-exercise therapy. Conclusions The results showed that 12 weeks of spa-exercise therapy had significant effect on reducing systolic blood pressure, increasing moisture, elasticity of skin in participants of middle-aged women, which means spa-exercise therapy may be used as a treatment on high blood pressure and cutaneous diseases. Further studies are anticipated to find out other various effects of spa-exercise therapy.

• Restorative Dentistry and Endodontics
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• v.31 no.4
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• pp.290-299
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• 2006

Objectives: The purpose of this study is to evaluate the effect of ethylene glycol analogs on modulus of elasticity and ultimate tensile strength of moist, demineralized dentin matrix. Methods: Dentin disks 0.5 mrn thick were prepared from mid-coronal dentin of extracted. unerupted, human third molars. 'I' beam and hour-glass shaped specimens were prepared from the disks, the ends protected with nail varnish and the central regions completely demineralized in 0.5M EDTA for 5 days. Ultimate tensile stress (UTS) and low strain modulus of elasticity (E) were determined with specimens immersed for 60 min in distilled water $(H_{2}O)$, ethylene glycol $(HO-CH_{2}-CH_{2}-OH)$, 2-methoxyethanol $(H_{3}CO-CH_{2}-CH_{2}-OH)$, and 1,2-dimethoxyethane $(H_{3}CO-CH_{2}-CH_{3}-OCH_{3})$ prior to testing in those same media. Modulus of elasticity was measured on the same specimens in a repeated measures experimental design. The results were analyzed with a one-way ANOVA on ranks, followed by Dunn's test at ${\alpha}\;=\;0.05$. Regression analysis examined the relationship between UTS or E and hoy's solubility parameter for hydrogen bonding $({\delta}_{h})$ of each solvent. Results: The UTS of demineralized dentin in water, ethylene glycol, 2-methoxyethanol, and 1,2-dimethoxyethane was 24 (3), 30 (5), 37 (6), and 45 (6) MPa, ${\times}$ (SD) N = 10. Low strain E for the same media were 16 (13), 23 (14), 52 (24), and 62 (22) MPa. Regression analysis of UTS vs ${\delta}_{h}$ revealed a significant $(p\;<\;0.0001,\;r\;=\;-0.99,\;R^{2}\;=\;0.98)$ inverse, exponential relationship. A similar inverse relationship was obtained between low strain E vs ${\delta}_{h}\;(p\;<\;0.0005,\;r\;=\;-0.93,\;R^{2}\;=\;0.86)$. Significance: The tensile properties of demineralized dentin are dependent upon the hydrogen bonding ability of polar solvents $({\delta}_{h})$. Solvents with low ${\delta}_{h}$ values may permit new interpeptide H-bonding in collagen that increases its tensile properties. Solvents with high ${\delta}_{h}$ values prevent the development of these new interpeptide H-bonds.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.4
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• pp.468-475
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• 2019

An end-line flame arrester allows free venting in combination with flame protection for vertical vent applications. End-line flame arresters are employed in various fields, especially in shipping. In flame arresters, springs are essential parts because the spring load and the spring's elasticity determine the hood opening moment. In addition, the spring has to work under a high-temperature condition because of the burning gas flame. Therefore, it is necessary to analyze the mechanical load and elasticity of the spring when the flame starts to appear. Based on simulations of the working process of a specific end-line flame arrester, a thermal and structural analysis of the spring is performed. A three-dimensional model of a burned spring is built using computational fluid dynamics (CFD) simulation. Results of the CFD analysis are input into a finite element method simulation to analyze the spring structure. The research team focused on three cases of spring loads: 43, 93, and 56 kg, correspondingly, at 150 mm of spring deflection. Consequently, the spring load was reduced by 10 kg after 5 min under a $1,000^{\circ}C$ heat condition. The simulation results can be used to predict and estimate the spring's load and elasticity at the burning time variation. Moreover, the obtained outcome can provide the industry with references to optimize the design of the spring as well as that of the flame arrester.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.4
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• pp.355-364
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• 2023

Lips have a unique desquamation process and moisturizing properties that are structurally different from ordinary skin. In particular, the turnover cycle of the stratum corneum is fast and the outermost stratum corneum is thin, so the amount of keratin is relatively high, and there are no skin appendages, so it is very vulnerable to maintaining moisture. In this study, we set three targets for lip care : stratum corneum, moisture, and barrier, and aimed to identify the potential of three target-specific ingredients for lips improvement. We confirmed the exfoliating, moisturizing, and barrier improvement efficacy of three target-specific ingredients which also have mild exfoliating effect. Specifically, we verified that Bacillus clausii extract improved skin exfoliation, gluconolactone improved skin moisture retention, and serine reinforced skin barrier function. To test the in vivo efficacy of the complex composed of three target-specific ingredients on the human lips, the lip balm manufactured with non-irritating range of concentration was applied, and we confirmed that it was effective in improving lip exfoliation·moisturizing·elasticity·wrinkles. Consequently, it was confirmed that the beauty and health indicators of the lips could be improved through the exfoliation-moisturization-barrier care of the lips and these ingredients were applied to LG H&H LIPCERIN products.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.5
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• pp.939-951
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• 2002

We propose a new multiscale Galerkin method based on interpolation wavelets for two-dimensional Poisson's and plane elasticity problems. The major contributions of the present work are: 1) full multiresolution numerical analysis is carried out, 2) general boundaries are handled by a fictitious domain method without using a penalty term or the Lagrange multiplier, 3) no special integration rule is necessary unlike in the (bi-)orthogonal wavelet-based methods, and 4) an efficient adaptive scheme is easy to incorporate. Several benchmark-type problems are considered to show the effectiveness and the potentials of the present approach. is 1-2m/s and impact deformation of the electrode depends on the strain rate at that velocity, the dynamic behavior of the sinter-forged Cu-Cr is a key to investigate the impact characteristics of the electrodes. The dynamic response of the material at the high strain rate is obtained from the split Hopkinson pressure bar test using disc-type specimens. Experimental results from both quasi-static and dynamic compressive tests are Interpolated to construct the Johnson-Cook model as the constitutive relation that should be applied to simulation of the dynamic behavior of the electrodes. The impact characteristics of a vacuum interrupter are investigated with computer simulations by changing the value of five parameters such as the initial velocity of a movable electrode, the added mass of a movable electrode, the wipe spring constant, initial offset of a wipe spring and the virtual fixed spring constant.

• Journal of the Korean Society of Safety
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• v.27 no.2
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• pp.49-56
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• 2012

If cement can be manufactured with industrial byproducts such as granulated blast furnace slag, phosphogypsum, and waste lime instead of clinker, there would be many advantages, including maximum use of these industrial byproducts for high value-added resources, conservation of natural resources and energy by omitting the use of clinker, minimized environmental pollution problems caused by CO2 discharge, and reduction of the production cost. By this reason, in this study, mechanical behavior tests of non-burnt cement concrete were performed, and elasticity modulus and stress-strain relationship of non-burnt cement concrete were proposed. 6 test members were manufactured and tested according to reinforcement ratio and concrete compressive strength. By the test results, there was no difference between ordinary concrete and non-burnt cement concrete of flexural behavior. In order to verify the proposed non-burnt cement concrete model, nonlinear analytical model was derived by using strain compatibility method. By the results of comparison between test results, ordinary concrete model and proposed model, The proposed model well predicted the flexural behavior of non-burnt cement concrete.

• Journal of the Korea Institute of Building Construction
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• v.12 no.1
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• pp.115-121
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• 2012

If cement could be manufactured with industrial byproducts such as granulated blast furnace slag, phosphogypsum, and waste lime rather than clinker, there would be many advantages, including the maximization of the use of these industrial byproducts for high value-added resources, the conservation of natural resources and energy by omitting the use of clinker, the minimization of environmental pollution problems caused by $CO_2$ discharge, and the reduction of the production cost. For this reason, in this study, mechanical behavior tests of non-sintered cement concrete were performed, and elasticity modulus and stress-strain relationship of non-sintered cement concrete were proposed. Nine test members were manufactured and tested according to reinforcement ratio and concrete compressive strength. According to the test results, there was no difference between general cement concrete and non-sintered cement concrete in terms of flexure and shear behavior.