• Advances in materials Research
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• v.5 no.4
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• pp.279-298
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• 2016

Present disquisition proposes an analytical solution method for exploring the buckling characteristics of porous magneto-electro-elastic functionally graded (MEE-FG) plates with various boundary conditions for the first time. Magneto electro mechanical properties of FGM plate are supposed to change through the thickness direction of plate. The rule of power-law is modified to consider influence of porosity according to two types of distribution namely even and uneven. Pores possibly occur inside FGMs due the result of technical problems that lead to creation of micro-voids in these materials. The variation of pores along the thickness direction influences the mechanical and physical properties. Four-variable tangential-exponential refined theory is employed to derive the governing equations and boundary conditions of porous FGM plate under magneto-electrical field via Hamilton's principle. An analytical solution procedure is exploited to achieve the non-dimensional buckling load of porous FG plate exposed to magneto-electrical field with various boundary condition. A parametric study is led to assess the efficacy of material graduation exponent, coefficient of porosity, porosity distribution, magnetic potential, electric voltage, boundary conditions, aspect ratio and side-to-thickness ratio on the non-dimensional buckling load of the plate made of magneto electro elastic FG materials with porosities. It is concluded that these parameters play remarkable roles on the dynamic behavior of porous MEE-FG plates. The results for simpler states are confirmed with known data in the literature. Presented numerical results can serve as benchmarks for future analyses of MEE-FG plates with porosity phases.

• Journal of Oral Medicine and Pain
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• v.40 no.4
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• pp.146-154
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• 2015

Purpose: The purpose of present study was to develop a method for assessing the chronological age of Korean adults based on the relationship between age and size of pulp cavity using dental radiographs of mandibular first molars. Methods: A total of 325 dental radiographs of Korean adults with known age and gender were selected for the study (199 males and 126 females) which were taken in the period between January 2009 and June 2014 at the Pusan National University Dental Hospital. The measurements were carried out on both orthopantomographs (OPGs) and intraoral periapical radiographs of mandibular first molar and the following ratios were calculated: pulp chamber floor height ratio (F/L), pulp chamber ceiling height ratio (R/L), and pulp chamber depth ratio (D/L). Results: The ratios of measurements on intraoral periapical images of mandible first molar generally produce more reliable data than the measurements on OPGs. The pulp chamber floor height ratio and pulp chamber thickness ratio showed significant correlation with age, whereas the pulp chamber ceiling height ratios showed weak correlation with age. It was found that the best correlations between the ratios and age were found for pulp chamber thickness ratios (r=-0.731 to -0.751). The multiple regression models were derived using 3 ratios that were significantly correlated with age. The determination coefficients ($R^2$) of the models ranged from 0.556 to 0.596. Conclusions: Our results indicate that the pulp chamber thickness and pulp chamber floor height in mandibular first molar are an age-dependent variable in adults which can be used to estimate age with reasonable accuracy. The higher image quality of dental radiographs will probably narrow the age estimation error and improve dental age estimation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.353-360
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• 2014

The model ice is created at KRISO (Korea Research Institute for Ships and Ocean Engineering) ice basin where model ship is tested to obtain the necessary data in order to design the ice breaking vessels and ocean structures operating in the northern pole sea area. Through the model ship test, ice breaking, clearing, ice-ship and ice-propeller interaction behavior can be obtained. Since mechanical properties of ice plate are required for the model test, some tests are performed to obtain the properties in this paper. First, ultrasonic devide is used to measure the thickness of the model ice plate and the results show the possibility of using ultrasonic method, yet more sophisticated device or special sensors are required to measure the ice thickness completely. And the defection of ice plate is measured using LVDT to compute the characteristic length of ice plate on the fluid, which is used to get the effective Young's modulus of model ice.

• YAKHAK HOEJI
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• v.36 no.3
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• pp.212-219
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• 1992

Although oral route is the most convenient route for drug administration, the short and variable transit of drug through GI tract restricts the sustained drug absorption after oral administration. Thus, for sustained absorption of drugs, it is desirable to prolong the GI transit time by retaining the dosage forms in the stomach. In this study, the enzyme-digestible swelling hydrogel was synthesized by heating the mixed solution of N-vinyl-2-pyrrolidone[monomer], acrylated albumin[crosslinking agent] and proxyphylline[drug] at $65^{\circ}C$ for 10 hours in the cylindrical test tube. The resultant hydrogel tablet (diameter; 0.77 cm, thickness; 0.47 cm) was designed to swell in the gastric fluid after oral administration to such a size that passing through the pylorus could be inhibited during the drug release. After releasing drug, the hydrogel was expected to be degraded by pepsin, an enzyme in the stomach, and eventually solubilized. Actually, the hydrogel synthesized in the study swelled to a size larger than the diameter of the pylorus ($1.3{\pm}0.7$ cm) and slowly digested in the presence of pepsin. Drug release from the hydrogel was prolonged up to about 12 hours. The swelling kinetics was dependent on albumin acrylation time, drug content and gel thickness. Particularly the gel thickness was the most important factor that influences on drug release. By adjusting these factors, the albumin-crosslinked hydrogel was expected to be retained in the stomach for up to 60 hours and used as a potential platform of drugs for long-term GI absorption.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.7
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• pp.414-423
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• 2016

In the present study, the $CuN_x-Cu-CuN_x$ layer the partial pressure ratio Cu metal of Ar and $N_2$ gas using a DC magnetron sputtering device, was generated by the In-situ method. $CuN_x$ layer was able to obtain a surface reflectance reduction effect from the advantages of the process and the external light. $CuN_x$ layer is gas partial pressure, DC the Power, the deposition time variable transmittance in response to the thickness and partial pressure ratio, the reflectance was measured. $Ar:N_2$ gas ratio 10:10(sccm), DC power 0.35 A, was derived Deposition time 90 sec optimum conditions. Thus, according to the optimal thickness and the composition ratio was derived surface reflectance of 20.75%. In addition, to derive the value of ${\Delta}$ Ra surface roughness of 0.467. It was derived $CuN_x$ band-gap energy of about 2.2 eV. Thus, to ensure a thickness and process conditions can be absorbed to maximize the light in a wavelength band in the visible light region. As a result, the implementation of the $12k{\Omega}$ base line resistance of using the Cu metal. This is, 5 inch Metal mesh TSP(L/S: $4/270{\mu}m$) is in the range of the reference operation.

• International Journal of Oral Biology
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• v.40 no.4
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• pp.175-182
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• 2015

Previous studies suggested that myelinated axons innervating rat molar pulps undergo morphological changes in their peripheral course. However, little information is available on the morphological feature of the parent axons at the site of origin. We therefore investigated the size of the myelinated parent axons and their morphological features at the proximal sensory root of the trigeminal ganglion by horseradish peroxidase (HRP) injection into rat upper molar pulps and subsequent light and electron microscopy. A total of 248 HRP-labeled myelinated axons investigated were highly variable in the size. Fiber area, fiber diameter, axon area (axoplasm area), axon diameter (axoplasm diameter), and myelin thickness were $11.32{\pm}8.36{\mu}m^2(0.80{\sim}53.17{\mu}m^2)$, $3.99{\pm}1.53{\mu}m(1.08{\sim}9.26{\mu}m)$, $8.70{\pm}6.30{\mu}m^2(0.70{\sim}41.83{\mu}m^2)$, $3.13{\pm}1.13{\mu}m(0.94{\sim}7.20{\mu}m)$ and $0.43{\pm}0.23{\mu}m(0.07{\sim}1.06{\mu}m)$, respectively. The g-ratio (axon diameter / fiber diameter) of the labeled axons was $0.79{\pm}0.05$ (0.61~0.91). Axon diameter was highly correlated with myelin thickness (correlation coefficients, r=0.83) but little correlated with g-ratio (r=-0.33) of individual myelinated parent axons. These results indicate that myelin thickness of the myelinated parent axons innervating rat molar pulps increase with increasing axon diameter, thus maintaining a constant g-ratio.

• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.493-501
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• 2007

Recently, in the domestic amount of materials,curtailment and economic efficiency security by purpose, tapered beam application is achieved, but the architectural design technology of today based on the material non-linear method does not consider solutions to problems such as brittle fracture. So, geometric non-linear evaluation thatincludes initial deformation, width-thickness ratio, web stiffener and unbraced length is required. Therefore, in this study, we used ANSYS, a proven finite elementanalysis program,and material and geometric non-linear analysis to study existing and completed tapered H-section as deep beam's analysis model. Main parameters include the width-thickness ratio of web, stiffener, and flange brace, with the experimental result obtained by main variable buckling and limit strength evaluation. We made certain that a large width-thickness ratio of the web decreases the buckling strength and short unbraced web significantly improves ductility.

• Korean Journal of Agricultural Science
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• v.46 no.3
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• pp.461-469
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• 2019

The aim of this study was to analyze the contribution of carcass traits (backfat thickness, eye muscle area, carcass weight and marbling score) and the season at slaughter to the price (auction and market) using squared semi-partial correlation. The season at slaughter (summer expressed as season_2, autumn as season_3, and winter as season_4) were added into the estimation as dummy variables, and spring was set as a default variable. In this study, the carcass grades of 22,298 Hanwoo steers slaughtered from 2012 to 2017 were used to performmultiple regression analysis. The rankings of the contribution of the carcass traits and the seasons at slaughter to the auction prices were in the order of marbling score (68.63%), season_4 (11.88%), backfat thickness (10.45%), eye muscle area (6.11%), season_3 (2.19%), season_2 (0.45%) and carcass weight (0.28%). (R-square of the regression = 0.4101). The rankings of the contribution to the total prices were in the order of carcass weight (51.74%), marbling score (32.12%), season_4 (6.04%), backfat thickness (5.54%), eye muscle area (3.22%), season_3 (1.14%), and season_2 (0.19%). (R-Square of the regression = 0.6486). As a result, season_3 and season_4 had a negative effect on the auction price and total price. Because of seasonal event such as Korean Thanksgiving Day and Korean New Year's Day on season_3 and season_4, much supply was needed to meet the high demand. Thus, the seasonal effect at slaughter could be another factor to be cosideredin when considering of slaughter or breeding.

• PNF and Movement
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• v.19 no.1
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• pp.127-135
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• 2021

Purpose: The purpose of this study was to determine the effect of the side-bridge exercise on the thicknesses of the external and internal obliques, the transverse abdominis, and the erector spinae, which are some of the trunk muscles of healthy adult males and females. Methods: There were 30 subjects divided into two groups with 15 subjects in the modified side-bridge exercise group and 15 subjects in the bridge exercise group. The changes in each variable were analyzed before the exercise, after three weeks, and after six weeks of exercise using a two-way repeated analysis of variance. The significance level was set at 0.05. When there was any interaction between the time of measurement and each group, a paired t-test was conducted to find the difference within groups and an independent-sample t-test was conducted to find the difference between groups. The significance level for both tests was set at 0.01. Results: There was a significant difference in the external and internal obliques and the erector spinae according to changes over time and the interactions between the time and groups (p < 0.05). However, there was a significant difference in the transverse abdominis only according to the interaction between the length of times (p < 0.05). Conclusion: The study results indicated that the modified side-bridge exercise significantly increased the thickness of the external and internal obliques and the erector spinae. This suggests the usability of the exercise in lumbar stabilization exercises in future studies and clinical fields.

• Advances in aircraft and spacecraft science
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• v.9 no.3
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• pp.169-193
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• 2022

By the present paper, both experimental and analytical models have been proposed to study the vibration behavior of partially bio-sourced sandwich panel with orthogonally stiffened core. For a variable mass fraction of Alfa fibers from 5% to 15%, impregnated in a Medapoxy STR resin, this panel were manufactured by molding the orthogonally stiffened core then attached it with both skins. Using simply supported boundary conditions, a free vibration test was carried out using an impact hammer for predicting the natural frequencies, the mode shapes and the damping coefficient versus the fibers content. In addition, an analytical model based on the Higher order Shear Deformation Theory (HSDT) was developed to predict natural frequencies and the mode shapes according to Navier's solution. From the experimental test, we have found that the frequency increases with the increase in the mass fraction of the fibers until 10%. Beyond this fraction, the frequencies give relatively lower values. For the analytical model, variation of the natural frequencies increased considerably with side-to-thickness ratio (a/H) and equivalent thickness of the core to thickness of the face (h_s/h). We concluded that, the vibration behavior was significantly influenced by geometrical and mechanical properties of the partially bio-sourced sandwich panel.