• Journal of Technologic Dentistry
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• v.40 no.1
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• pp.41-47
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• 2018

Purpose: The purpose of this study was to analyze the biomechanical properties of the dental implants on the supporting bone using three-dimensional finite element method when three different abutment materials were applied to the implant system. Methods: Three different dental implant models were fabricated by applying Ti, PEEK, and CRE-PEEK (60% carbon-reinforced PEEK) to abutment material. The abutment and connecting screw from the fixture was applied with a tightening torque of 20 Ncm. And then, total loads of 150 N were applied in an $30^{\circ}oblique$ direction (to the vertical). The structural stability of dental implants on the supporting bone was analyzed using Von Mises stress and principal stress values. Results: The maximum tensile stress of the cortical bone was highest at 12.6 MPa in the PEEK abutment (Model-B). Ti abutment (Model-A) and CRE-PEEK abutment (Model-C) showed similar stress distributions (10.6 and 10.3 MPa, respectively). And the maximum compressive principal stress was similar in all models. The Von Mises stress value delivered to the bone around the implant was highest at 16.5 MPa in Model-B. On the other hand, Model-A and C showed similar stress distributions (14.0 and 13.8 MPa, respectively). In addition, the maximum equivalent stress applied to the abutment was highest at 629.8 MPa in Model-A. The stress distribution in Model-C was 573.9 MPa. Whereas, Model-B showed the lowest value at 165.6 MPa. Conclusion : The dental implant supporting bone system using PEEK material seems to have the possibility of supporting bone fracture. It was found that the CRE-PEEK abutment can reduce the elastic deformation and reduce the stress value of the interfacial bone.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.2
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• pp.242-247
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• 1987

Electrophysical phenomena at the silicon semiconductor-electrolyte solution interfaces were analyzed based on the zeta potential of the electrical double layer and microelectrophoresis. The suspensions were composed of the p or n-type silicon particles suspended in the KCI or pH buffer solutions. The approximate diameter of the prepared and sampled sioicon semiconductor pardticles was 1.5\ulcorner. The sign of the zeta poetntials of the p and n-type silicon particles in the KCl and pH buffer solution was positive. A range of electrophoretic mobilities of the p and n-type silicons in the KCl solutions was 5.5-8.9x10**-4 cm\ulcornerV-sec and 4.2-7.9x10**-4cm\ulcornerV-sec, respectively. The range of zeta potentials corresponding to the electrophoretic mobilities is 70.4-114.0mV nad 53.9-101.2mV, respectively. On the other hand, a range of electrophoretic mobilities of the p and n-type silicons in the pH buffer solutions was 1.1x10**-4-2.2x10**-3cm\ulcornerV-sec and 0-2.1x10**-3cm\ulcornerV-sec, respectively. The range of zeta potentials corresponding to the electrophoretic mobilities is 14.1-281.6mV and 0-268.8mV, respectively. The zeta potentials and electrical double layers of the doped silicon semiconductors are decisively influenced by the positively charged ions in the solutions. The maximum values of the zeta potentials in the KCl solutions appeared at a concentration of about 10-\ulcorner. The isoelectric point of the n-type silicon semiconductors appeared at about a pH 7. The effect of the space charge of the doped silicon semiconductors can be neglected compare with the effect of the surface charge.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.9
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• pp.863-872
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• 2005

It is important to control indoor environment for influence on health and comfort of occupants in large-sized discount stores. On the other hand large-sized discount stores have a large number of visitors, vestibules, open spaces, high energy consumption and increasing of outside air intake. This study aims to offer the design data of building services system that can save energy and control environment through field measurement selecting two large-sized discount stores. Indoor environment factors such as temperature, relative humidity, air velocity and concentrations of $CO_2$, CO gas and TSP were measured and evaluated. In each case of $CO_2$, and CO gas, its maximum values were 2,800 ppm and 20 ppm. So proper strategy for the indoor air quality is indispensable in this type of building. Dry bulb temperature varies from $18^{\circ}C$ to $28^{\circ}C$ according to a measuring point and time. From this results, it is inferred these buildings had excessive equipment capacity. In terms of economical and environmental points, these data will be utilized to the design of HVAC system of retail facilities.

• YAKHAK HOEJI
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• v.25 no.3
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• pp.89-99
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• 1981

This study was performed to investigate the contamination level of heavy metals in freshwater flshes. The samples of 92 cases were collected at 7 areas located on HanRiver from November to December in 1980. Contents of heavy metals: cadmium, lead, copper, chromium and zinc were analyzed by atomic absorption spectrophotometry. The results were as follows: 1. Generally mean value of the heavy metal contents of fishes collected on lower parts of Han River were higher than those of upper parts. 2. In the cadmium contents, the highest value was $20.52{\pm}5.10$ ppb in Carassius auratus, and the values at Hannam and Noryangjin area were higher than those at other parts on Han River. 3. In the lead contents, the highest was $0.29{\pm}0.03ppm$ in Carassius auratus and that in Parasilurus asotus was the lowest $0.12{\pm}0.02ppm$ Mean contents of lead in the samples of Hannam and Haengjue area were higher than those of other area 4. In the copper contents, the highest value was $3.13{\pm}0.34ppm$ in Carassius auratus and the contents of fishes of Haengjue area was higher than those of any other area. It was significant among the species, but not among the collecting areas in copper contents. 5. In the chromium contents, the highest was $1.16{\pm}0.12ppm$ in Carassius auratus and that in Parasilurus asotus was the lowest $0.21{\pm}0.01ppm$ The contents of samples of Hannam and Noryangjin area were also higher than those of other area. 6. In the zinc contents, that in Arassius auratus was the highest value with $14.06{\pm}1.13ppm$ and that in Parasilurus asotus was the lowest $4.79{\pm}0.53ppm$. On the other hand, it was significant among the species and collecting areas. 7. Accumulation of heavy metals in freshwater fishes is tended to increase with growth.

• Korean Journal of Crystallography
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• v.11 no.3
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• pp.162-166
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• 2000

KD₂PO₄ single crystals were grown from D₂O with reagent KH₂PO₄ and the crystal structure was determined by X-ray and neutron diffraction methods. The crystals are tetragonal at room temperature, I42d, with lattice parameters of a=7.4633(7), c=6.9785(5) Å and Z=4. Intensity data were collected on an Enraf-nonius CAD4 diffractometer with a graphite monochromated MoK/sub α/ radiation (λ=0.7107Å) and on the neutron four circle single crystal diffractometer with Ge(331) monochromated neutron beam (λ=0.997Å). The structure was refined by full-matrix least-square to final R and wR values of 0.030 and 0.072, respectively, for 204 observed reflections with I>2σ(I) by X-ray diffraction and to final R=0.041 and wR=0.096 for 144 observed relfecdtions by neutron diffraction. The O…O distance of 2.516(4)Å obtained by X-ray diffraction is the same as that of 2.515(4)Å by neutron diffraction. On the other hand, the O-D/H distance of 0.84(4)Å by X-ray diffraction is considerably shorter than 1.029(7) Åby neutron diffraction. Hydrogen and deuterium can be readily distinguished by neutrons. In this crystal 66% of H-positions were substituted by D and the rest 34% occupied by H. The phase transition temperature of DKDP obtained with deuteration levels is f193K. This value agrees fairly well with the result of DSC measurement. The nuclear density distribution by neutron diffraction provides an observation of the disordered state of D/H in KD₂PO₄ at room temperature.

• International Journal of Knowledge Content Development & Technology
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• v.7 no.1
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• pp.57-78
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• 2017

There are several statistical classification algorithms available for land use/land cover classification. However, each has a certain bias or compromise. Some methods like the parallel piped approach in supervised classification, cannot classify continuous regions within a feature. On the other hand, while unsupervised classification method takes maximum advantage of spectral variability in an image, the maximally separable clusters in spectral space may not do much for our perception of important classes in a given study area. In this research, the output of an ANN algorithm was compared with the Possibilistic c-Means an improvement of the fuzzy c-Means on both moderate resolutions Landsat8 and a high resolution Formosat 2 images. The Formosat 2 image comes with an 8m spectral resolution on the multispectral data. This multispectral image data was resampled to 10m in order to maintain a uniform ratio of 1:3 against Landsat 8 image. Six classes were chosen for analysis including: Dense forest, eucalyptus, water, grassland, wheat and riverine sand. Using a standard false color composite (FCC), the six features reflected differently in the infrared region with wheat producing the brightest pixel values. Signature collection per class was therefore easily obtained for all classifications. The output of both ANN and FCM, were analyzed separately for accuracy and an error matrix generated to assess the quality and accuracy of the classification algorithms. When you compare the results of the two methods on a per-class-basis, ANN had a crisper output compared to PCM which yielded clusters with pixels especially on the moderate resolution Landsat 8 imagery.

• The Research Journal of the Costume Culture
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• v.17 no.6
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• pp.1141-1154
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• 2009

As a preliminary research of body characteristics analysis of Korean obese woman, this study aims to select optimal obesity judgment tools for reliable sampling of obese subjects from 2,425 female measurement data out of 2004 Size Korea project's raw data. From previous researches related to obesity, 7 obesity judgment tools were chosen. 2007 obesity rate(26.3%) of Korean female adults was refered in selecting optimal obesity judgment criteria in the study. The results are as follows. Firstly, it was verified that BMI was the most suitable in judging and sampling the obese subjects by the percentile analysis. R$\ddot{o}$hrer index was also reliable in grouping the obese subjects from a population. Secondly, it was concluded that the obesity ratios of relative weight 120 and higher group, R$\ddot{o}$hrer index 1.6 and higher group and waist girth 80cm and higher group were the most similar to obesity rate of Korean female adults by 2007 National Health & Nutrition Survey. Thirdly, 30 direct measurements, age, 2 drop values and 6 ratios of 7 groups by the obesity judgment tools showed the significance each other at p<0.001 level. On the other hand, "bust point to bust point" and "waist to hip length" measurements didn't show the significant differences among 7 groups. Conclusively, 4 to 5 satisfactions out of 7 obesity judgment criteria were adequate and sufficient in sampling the obese subjects. If it is needed the strict criteria for judging the obesity, 5 satisfactions and higher group will be the best choice as the obese subjects. However 4 satisfactions and higher group generally, will be adequate for sampling of the obese subjects.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.577-582
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• 2007

A variational formulation for plane elasticity problems is derived based on an isogeometric approach. The isogeometric analysis is an emerging methodology such that the basis functions in analysis domain arc generated directly from NURBS (Non-Uniform Rational B-Splines) geometry. Thus. the solution space can be represented in terms of the same functions to represent the geometry. The coefficients of basis functions or the control variables play the role of degrees-of-freedom. Furthermore, due to h-. p-, and k-refinement schemes, the high order geometric features can be described exactly and easily without tedious re-meshing process. The isogeometric sensitivity analysis method enables us to analyze arbitrarily shaped structures without re-meshing. Also, it provides a precise construction method of finite element model to exactly represent geometry using B-spline base functions in CAD geometric modeling. To obtain precise shape sensitivity, the normal and curvature of boundary should be taken into account in the shape sensitivity expressions. However, in conventional finite element methods, the normal information is inaccurate and the curvature is generally missing due to the use of linear interpolation functions. A continuum-based adjoint sensitivity analysis method using the isogeometric approach is derived for the plane elasticity problems. The conventional shape optimization using the finite element method has some difficulties in the parameterization of boundary. In isogeometric analysis, however, the geometric properties arc already embedded in the B-spline shape functions and control points. The perturbation of control points in isogeometric analysis automatically results in shape changes. Using the conventional finite clement method, the inter-element continuity of the design space is not guaranteed so that the normal vector and curvature arc not accurate enough. On tile other hand, in isogeometric analysis, these values arc continuous over the whole design space so that accurate shape sensitivity can be obtained. Through numerical examples, the developed isogeometric sensitivity analysis method is verified to show excellent agreement with finite difference sensitivity.

• Journal of the Korean Dietetic Association
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• v.19 no.1
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• pp.14-24
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• 2013

The purpose of this study was to estimate the prevalence of hypertension, and to assess the risk factors associated with hypertension in elderly (over 65 years old) Koreans, using data from the 4th Korean National Health & Nutrition Examination Survey (the 4th KNHANES), 2007~2009. A total of 1,887 participants were analyzed for assessing the risk factors after excluding those who took hypertension medicines or underwent diet therapy (hypertension perceivers). On the other hand, in analyzing prevalence, a total of 3,526 people were analyzed, including hypertension perceivers. Hypertension was more frequently found in female (64.1%) and urban (62.0%) groups compared to male (55.6%) and rural (57.4%) groups. The mean age of the hypertensive group was significantly higher than that of normal group. The mean values of total cholesterol levels were also significantly higher in the hypertensive group, while body weight, waist circumference, fasting blood glucose, hemoglobin, hematocrit, LDL-cholesterol, and HDL-cholesterol were not. Multiple logistic regression showed that smoking was significantly related to the prevalence of hypertension, but alcohol drinking, stress, obesity, hypercholesterolemia, hypertriglyceridemia, diabetes, anemia, and nutrient intakes were not. The results of this study does not support clear relations of hypertension with chronic diseases including obesity, hyperlipidemia, anemia, and diabetes as well as nutrient intakes among a Korean elderly population. A prospective long-term research study is needed to establish the effects of these factors on hypertension.

• Journal of the Korean Dietetic Association
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• v.23 no.4
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• pp.337-349
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• 2017

This study evaluated the quality characteristics of jelly prepared with different levels (0%, 5%, 10%, 15%, 20%, and 25%) of wild carrot (WC, Daucus carota L.) juice as a care food for the elderly. The lightness, redness, yellowness, and delta (${\Delta}$) values of the jelly (Control, WCJ5, WCJ10, WCJ15, WCJ20, and WCJ25) decreased with increasing amounts of wild carrot juice added. The mechanical properties, such as hardness, springiness, chewiness, and gumminess, of the jelly were decreased with increasing amounts of wild carrot juice added. The total polyphenol and total flavonoid contents of the jelly increased with increasing amounts of wild carrot juice added. The DPPH radical scavenging activity ($IC_{50}$) also increased with increasing amounts of wild carrot juice added. The ${\alpha}$-glucosidase inhibitory effects of wild carrot (WC) and WCJ25 were 71% and 54.4%, respectively, compared to the positive control (acarbose). The lipase inhibitory effects of WC and WCJ25 were 44.2% and 14.4%, respectively, compared to the positive control group (orlistat). On the other hand, the sensory evaluation score was the best at WCJ20, which contained 20% wild carrot juice. In conclusion, WCJ20 or WCJ25 is expected to be a care food for the elderly with respect to texture as well as the antioxidant and enzymatic activity (${\alpha}$-glucosidase inhibitory and lipase inhibitory activities).