• Structural Engineering and Mechanics
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• v.61 no.4
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• pp.497-510
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• 2017

A framed structure may be composed of two sub-structures, which are linked by a hinged joint. One sub-structure is the primary system and the other is the secondary system. The primary system, which is subjected to the periodic external load, can give rise to an auto-parametric resonance of the second system. Considering the geometric-stiffness effect produced by the axially internal force, the element equation of motion is derived by the extended Hamilton's principle. The element equations are then assembled into the global non-homogeneous Mathieu-Hill equations. The Newmark's method is introduced to solve the time-history responses of the non-homogeneous Mathieu-Hill equations. The energy-growth exponent/coefficient (EGE/EGC) and a finite-time Lyapunov exponent (FLE) are proposed for determining the auto-parametric instability boundaries of the structural system. The auto-parametric instabilities are numerically analyzed for the two frames. The influence of relative stiffness between the primary and secondary systems on the auto-parametric instability boundaries is investigated. A phenomenon of the "auto-parametric internal resonance" (the auto-parametric resonance of the second system induced by a normal resonance of the primary system) is predicted through the two numerical examples. The risk of auto-parametric internal resonance is emphasized. An auto-parametric resonance experiment of a ${\Gamma}$-shaped frame is conducted for verifying the theoretical predictions and present calculation method.

• Journal of the Korea Furniture Society
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• v.14 no.2
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• pp.87-96
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• 2003

This study explores aesthetics and materials used in domestic and international hanger designs from 1850 to 2003. At the second half of the nineteenth century, most hangers were handmade and made of wood and metal. At the first half of the twentieth century, such diverse materials as paper, plastics, and leather began to use other than such typical materials as wood and metal at the previous decades. However, from the second half of the twentieth century the use of different types of plastics led to artistic abnormal shapes within typical triangular types. Moreover, this study also examines hangers by its functions: primary, portable, and multi-functional types.

• Korean Journal of Mathematics
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• v.26 no.4
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• pp.675-681
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• 2018

In the paper, by virtue of techniques in combinatorial analysis, the authors simplify three families of nonlinear ordinary differential equations in terms of the Stirling numbers of the first kind and establish a new family of nonlinear ordinary differential equations in terms of the Stirling numbers of the second kind.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.167-174
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• 2008

Mandibular first molar and primary molars usually have two roots, on the mesial and distal sides. Occasionally, these molars have an extra root located in the distolingual aspect. Prevalence of the 3-rooted first permanent molar shows ethnic variation, ranging from about 3% in Caucasian to about 20% in Mongoloid group, which includes Chinese, Japanese, Eskimo, American and Canadian Indians. The frequency of the mandibular molar with three roots decreases in the order of the first permanent molar, the second primary molar, and the first primary molar. If the mandibular first or second primary molar has an additional distolingual root, the adjacent molars, including the first permanent molar, posterior to it also may have it. Coronal morphologic change can occur in the mandibular first primary molars with three roots: the crown had more triangular-shape compared to the one with two roots, possibly affected by the presence of additional distolingual root. Clinically, exact diagnosis and treatment should be taken with those teeth for pulp canal treatment, extraction, and SS Cr.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5B
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• pp.469-479
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• 2006

In order to investigate characteristics of the primary flow and the secondary currents in meandering channels, the laboratory experiments were conducted in S-curved channels with angle of bend, $150^{\circ}$, and sinuosity of 1.52. The experimental conditions was decided varying average depth and velocity. Under these experimental conditions, spatial variations of the secondary currents in multiple bends were observed. The experimental results revealed that the distribution of primary flow in straight section is symmetric without respect to the experimental condition and the maximum velocity line of the primary flow occurs along the shortest path in experimental channel, supporting the result of previous works. The secondary currents in second bend became more developed than those in first bend. Particularly, the outer bank cell developed distinctively and the secondary current intensity was low at the straight section and high at the bends, periodically. Also, the secondary current intensity at the bends was as twice to three times as that at the straight section, and has its maximum value at the second bend. The turbulent flow characteristics of meandering channel was investigated with turbulent intensity of the primary flow and Reynolds shear stress. It was observed that the turbulent intensity is increasing when the velocity deviation of the primary flow is large whereas Reynolds shear stress increases when both the velocity deviation of the primary flow and the secondary current are large.

• Journal of Yeungnam Medical Science
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• v.27 no.2
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• pp.98-104
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• 2010

Primary anterior mediastinal neoplasms comprise a diverse group of tumors and account for 50% of all mediastinal masses. Thymic epithelial neoplasm are most common and classified into thymoma, invasive thymoma, and thymic carcinoma. Neuroendocrine differentiation of thymic epithelial neoplasm are rare malignancies. Germ cell tumor (GCT) is second most common anterior mediastinal tumor and most of them are mature cystic teratoma. Malignant mediastinal GCT are rare than benign. Primary thoracic lymphoma is rare than thoracic involvement of systemic lymphoma and most common location of primary thoracic lymphoma is anterior mediastinum. The clinical and radiologic appearance of the most common masses are reviewed.

• Advances in pediatric surgery
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• v.11 no.1
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• pp.34-39
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• 2005

Two cases of primary torsion of the greater omentum were described. The first patient was a 5-year-old boy who was admitted to the hospital because of severe abdominal pain for 1 day. The The clinical features were similar to perforated acute appendicitis. Laparotomy revealed a normal appendix and the greater omentum twisted around its pedicle. The second patient was a 7-year-old girl admitted to the hospital because of abdominal pain in right lower quadrant for 2 days. The clinical features? were that of acute appendicitis. Laparotomy revealed a normal appendix and primary torsion of greater omentum around its pedicle. In both cases, resection of twisted omentum and incidental appendectomy were done. The microscopic findings in two cases consisted of congestion and vascular hemorrhage. Both patients recovered uneventfully. Torsion of the greater omentum, therefore, may be added to the entities to consider in the differential diagnosis of acute appendicitis.

• Fashion & Textile Research Journal
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• v.4 no.2
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• pp.163-168
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• 2002

For the purpose of investigating the factor of foot and calf growth of primary-school children who are fast-growing during this period a group of the 1st graders of primary-school had been the subject of this measurement in 1995 and there after they became the subject again in 1997, 1999 when they were the 3th, 5th graders measurement was carried out in 30 items including status and weight and marthin-type measure and foot-print were used for this measurement as the result, stature is correlated with height items and length items of foot and calf weight is correlated with width and circumference items of foot and calf angle of the first toe showed the highest growth like 3rd graders, heel circumference had rapidly grown rather than in the part of foot circumference in the factor analysis df foot measurement of 10-year, the first, second factors, appeared the size of shoes, in case of 12-year the first factor with status appeared the size of shoes.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2407-2410
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• 2003

In this paper, we propose a new stereoscopic video conversion methodology that converts two-dimensional (2-D) MPEG-4 video to stereoscopic video. In MPEG-4, each Image is composed of background object and primary object. In the first step of the conversion methodology, the camera motion type is determined for stereo Image generation. In the second step, the object-based stereo image generation is carried out. The background object makes use of a current image and a delayed image for its stereo image generation. On the other hand, the primary object uses a current image and its horizontally-shifted version to avoid the possible vertical parallax that could happen. Furthermore, URFA(Uncovered Region Filling Algorithm) is applied in the uncovered region which might be created after the stereo image generation of a primary object. In our experiment, show MPEG-4 test video and its stereoscopic video based upon out proposed methodology and analyze Its results.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.43-46
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• 2012

The oxygen concentration of primary oxidizer is decided under 10% due to flammable risk. It can be a spontaneous combustion inside burner or tube if the excess oxygen is added to primary oxidizer in Oxy-PC burner. In this case, the rest oxygen which can not be injected to primary oxidizer should be injected to another port. If added it to a second oxidizer, the ignition is unstable at outlet of burner. Accordingly an extra lancing port is needed to insert into the burner unlike other common air mode. And the flame formation and combustion characteristic differ from lancing port position. Therefore we observed flame formation which has stable combustion characteristic according to the shape and position of lancing port.