• Restorative Dentistry and Endodontics
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• v.25 no.3
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• pp.381-389
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• 2000

Lateral condensation with gutta-percha and sealer has been shown to provide an excellent apical seal; however, the lateral condensation technique has demonstrated less favorable apical leakage results in curved canals when compared with straight canals. Placement of endodontic spreaders to within 1 to 2mm of the root canal working length has been advocated for optimum gutta-percha obturation. Due to their stiffness, stainless-steel(SS) spreaders will often fail to achieve this position in curved canals. Newly marketed nickel-titanium(NT) spreaders may offer an advantage in this regard due to the increased flexibility of these instruments. The purpose of this study was to evaluate the effect of NT finger spreader on the sealing ability in lateral condensation technique, compared with conventional SS finger spreader. Twenty four standardized resin models simulating curved canals(30 degree) were randomly placed into 2 groups and instrumented to a #30 master apical file size with Ni-Ti Profile .04 taper series using step down technique. Each groups was obturated with standardized gutta-percha cone by standard lateral condensation technique using SS finger spreader, NT finger spreader. And then, each model was sectioned horizontally with microtome at 1, 2, 3, 4, 5mm levels from the apex. At each of 5 levels, ratio of the area of gutta-percha was obtained by calculating the area of gutta-percha to the total area of the canal. The data collected were then analyzed statistically using a t test for independent samples. The results as follows ; 1. The total mean ratio of area of gutta-percha was 89.20${\pm}$7.00(%) for SS spreader group. 92.20${\pm}$5.17(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). 2. At 3mm level, the mean ratio of area of gutta-percha was 88.32${\pm}$5.41(%) for SS spreader group, 95.25${\pm}$2.60(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). At 1,2,4mm levels, NT spreader group showed greater mean ratio of area of gutta-percha than SS spreader group, too. But there was no statistically significant difference. 3. At 5mm level, the mean ratio of area of gutta-percha was 91.83${\pm}$3.42(%) for SS spreader group, 87.91${\pm}$3.68(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). This study concluded that the NT spreader demonstrated somewhat favorable apical sealing effect than SS spreader in prepared curved canals. The clinical use of NT spreaders may enhance our ability to create better apical seals in curved canals, but further studies in this area will help clarify some of the remaining areas with which practitioners are concerned, such as compaction forces exerted by NT spreaders.

• Journal of Korea Water Resources Association
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• v.45 no.4
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• pp.349-360
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• 2012

A horizontally curvilinear non-hydrostatic free surface model that was applicable to three-dimensional viscous flows was developed. The proposed model employed a top-layer equation to close kinematic free-surface boundary condition, and an isotropic k-${\varepsilon}$ model to close turbulence viscosity in the Reynolds averaged Navier-Stokes equation. The model solved the governing equations with a fractional step method, which solved intermediate velocities in the advection-diffusion step, and corrects these provisional velocities by accounting for source terms including pressure gradient and gravity acceleration. Numerical applications were implemented to the wind-driven currents in a two-dimensional closed basin, the flow in a steep-sided trench, and the flow in a strongly-curved channel accounting for secondary current by the centrifugal force. Through the numerical simulations, the model showed its capability that were in good agreement with experimental data with respect to free surface elevation, velocity, and turbulence characteristics.

• The Journal of Korea Robotics Society
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• v.10 no.3
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• pp.146-153
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• 2015

In order to contain as much information as possible in a single image, a wide FOV(Field-Of-View) imaging system is required. The catadioptric imaging system with hyperbolic cylinder mirror can acquire over 180 degree horizontal FOV realtime panorama image by using a conventional camera. Because the hyperbolic cylinder mirror has a curved surface in horizontal axis, the original image acquired from the imaging system has the geometrical distortion, which requires the image processing algorithm for reconstruction. In this paper, the image reconstruction algorithms for two cases are studied: (1) to obtain an image with uniform angular resolution and (2) to obtain horizontally rectilinear image. The image acquisition model of the hyperbolic cylinder mirror imaging system is analyzed by the geometrical optics and the image reconstruction algorithms are proposed based on the image acquisition model. To show the validity of the proposed algorithms, experiments are carried out and presented in this paper. The experimental results show that the reconstructed images have a uniform angular resolution and a rectilinear form in horizontal axis, which are natural to human.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.3
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• pp.18-31
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• 1999

The research deals with external space Seowon(lecture hall) dedicated to education and memorial rises in Sangju area of Choson Dynasty. Characteristics of Seowon as follow; 1. Seowon of Sangju area were built from the middle of 17C to the beginning of 18C. Ideological background of building functioning were grafted into the belief in the three God governing Childbirth, the theory of feng-shui(wind-and water-magic) which is in close connection with the principles of yin and yang, and confucianism and the philosophy of lao-tze and chung-tze. The formation of space were horizontally arrangement and vertical arrangement as the first-learning and then-ancestor shrine of Youngnam provinces. 2. Background and factors of site selection were applied geographical feature, tried to connect owner home town. 3. The shape of path of flow were simple of vertical and curved composition, were continued, were stabilized through composition of human scale's space by reasonable internal. A case of Sangju area, D/H ratio of the front area of buildings and courts was as follows. D/H=1>Hyangkyo> houses on the river>temples>lecture halls. D/H ratio ot the backside areas is as follows. D/H=1>Hyangkyo>houses on the river>lecture halls. 4. Inner garden were planted deciduous than evergreen trees with Lagerstroemia indica. Enclosed dominant trees were planted by Pinus densiflora, Querces seuata.construct GEM strain, and examined for the expression and functional stability in microcosms.

• Journal of the Korean housing association
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• v.20 no.4
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• pp.1-9
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• 2009

In this study, an examination and an analysis are carried out on the forms and components of the access spaces of hotel entrances from the front gate of five star hotels in Jejudo, Korea. The results of the study are as follows. In terms of the arrangement of the hotel, city hotels with a relatively narrow site area are influenced by site shape, while resort hotels with a relatively wide site area are affected by the environment. However, the location of the front gate was determined by the access road from the outside. Therefore, forms of access space are related to the front gate, which is governed by the access road, and to the entrance, which is determined by the hotel arrangement. If the front gate is in line with the hotel entrance, a straight line and the hotel are arranged vertically to the front gate(side arrangement) or the hotel is arranged horizontally to the front gate, but if the entrance is not in line with the front gate, it appears as a curved shape. However, those who use their own cars have a variety of choices for access route depending on the location of the parking lot.

• Journal of Korean Society of Steel Construction
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• v.22 no.5
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• pp.465-475
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• 2010

In the horizontally curved bridges, girders are subjected to the combined action of vertical bending and torsion due to their curvatures without any eccentric loads. As subjected to bending and torsion, the ultimate strength of steel/concrete composite box girders are limited by the diagonal tensile stress in the deck concrete induced by the St. Venant torsion. To determine the ultimate strength of composite box girders in bending and torsion and their interactions, this study conducted a 3-dimensional FEA and classical strength of materials investigation. Using ABAQUS, the FEA fully utilized advanced nonlinear analysis techniques simulating material/geometrical nonlinearity and post-cracking behaviors. The ultimate strength from numerical data were compared with theoretically derived values. Concurrent compressive stresses in the concrete deck improve the shear-resisting capacity of concrete, thereby resulting in an increased torsional resistance of the composite box girder in positive bending. The proposed interaction equation is very simple yet it provides a rational lower bound in determining the ultimate strength of concrete/steel composite box girders.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.5
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• pp.762-769
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• 2009

A canoe is one of the most popular boats in leisure on the water. Generally canoe has been built by good wooden strips. And canoe built by FRP is used for business recently. But by the users' demands for good quality and the restriction to environmental pollution the wooden canoes are required for personal and canoe building business. The modern wooden canoes were built by the strip construction method are used typically. However it is not suitable for the mass productivity requires effective resource operations and managements of men, materials, times, and price. On this paper the new construction method, called the piling-up laminated construction method, is studied to building a canoe using the piling-up with the laminated wooden plates gives more productivity than the others. First a canoe with various curved surfaces is designed from 3D design system. And the hull of canoe model is divided horizontally to generating the laminated plates that will be converting real wooden plates available from the market and will be routed by the manufacturing machine. After the simulating and analyzing of piling-up with the laminated plates, the canoe is building with less times, less men, less resources, and lower price than other method, avoid of the requirements of additional building tools. On the next paper the constructing of a real canoe using the manufactured wooden plates will be studied.

• Fashion & Textile Research Journal
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• v.24 no.4
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• pp.372-385
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• 2022

In this study, the patterns expressed on nineteenth-century blue and white porcelain among Joseon white porcelain were selected as the material for the development of the car seat fabric design. It was intended to be applied to car seat design by incorporating Korea's own traditional patterns to fit modern sensibility. First, seven pieces of nineteenth-century blue and white porcelain were selected through the literature, and motifs were produced using adobe illustrator, a computer graphic program. Seven car seat fabric designs were developed according to the construction method and development method of the produced motif. Work 1 was designed to elicit a soft and feminine atmosphere using the peony pattern shown in Table 1-1. Work 2 aimed to express a luxurious atmosphere using the image of the mountain expressed in Table 1-2 as a design material. Works 3 was designed by freely arranging the letters of luck expressed in Table 1-3 to form a free and dynamic image. Work 4 was intended to express a stable and rhythmic atmosphere by horizontally arranging the images of the gently curved wings, tail, and rhythmical tail feathers of the phoenix expressed in Table 1-4. Work 5 was designed in a vertical arrangement using the patterns and silhouettes of the tiger's back expressed in Table 1-5. Work 6 was designed using the wave pattern expressed in Table 1-6 to replicate the rhythmic atmosphere. Work 7 was designed using the images of rocks, waves, and the sun in Table 1-7 to express a calm and antique atmosphere.

• Restorative Dentistry and Endodontics
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• v.31 no.2
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• pp.96-102
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• 2006

There are various factors affecting the fracture of NiTi rotary files. This study was performed to evaluate the effect of cross sectional area, pecking motion and pecking distance on the cyclic fatigue fracture of different NiTi files. Five different NiTi $files-Profile^{(R)}$ (Maillefer, Ballaigue, Switzerland), $ProTaper^{TM}$(Maillefer, Ballaigue, Switzerland), $K3^{(R)}$ (SybronEndo. Orange, CA) , Hero $642^{(R)}$ (Micro-mega, Besancon, France), Hero $Shaper^{(R)}$ (Micro-mega, Besancon, France)-were used. Each file was embedded in temporary resin, sectioned horizontally and observed with scanning electron microscope. The ratio of cross-sectional area to the circumscribed circle was calculated. Special device was fabricated to simulate the cyclic fatigue fracture of NiTi file in the curved canal,. On this device, NiTi files were rotated (300rpm) with different pecking distances (3 mm or 6 mm) and with different motions (static motion or dynamic pecking motion) . Time until fracture occurs was measured. The results demonstrated that cross-sectional area didn't have any effect on the time of file fracture. Among the files, $Profile^{(R)}$ took the longest time to be fractured. Between the pecking motions, dynamic motion took the longer time to be fractured than static motion. There was no significant difference between the pecking distances with dynamic motion, however with static motion, the longer time was taken at 3mm distance. In this study, we could suggest that dynamic pecking motion would lengthen the time for NiTi file to be fractured from cyclic fatigue.

• Korean Journal of Plant Resources
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• v.37 no.1
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• pp.22-34
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• 2024

Recently, in several regions of Korea, we discovered the occurrence of Sagina micropetala Rauschert and S. procumbens L. All the plants of the genus Sagina growing in Korea are 5-merous and belong to the sect. Spergella. However, the two taxa we discovered belong to the sect. Saginella and are 4-merous. In addition, morphological characteristics such as sepals during the fruiting season and seeds were significantly different from those of species of the genus Sagina that occur in Korea. To clearly identify these species, we compared and observed their primary morphological characteristics using illustrated books and literature. Morphologically, S. micropetala exhibits the following traits: pubescence along the leaf margin, horizontally spreading sepals with red margins, and convex protrusions on the seed surface. In contrast, S. procumbens can be distinguished by its pedicels, which are curved during the flowering season and erect during the fruiting season. This plant also has broadly ovate sepals with white or yellowish-green margins, and flat seed surface protrusions. In terms of molecular analyses, 19 samples of Sagina were divided into two clades (S. micropetala and S. procumbens), confirming the taxonomic identity of the Sagina spp.