• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.1 s.53
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• pp.169-178
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• 2009

Ring-type steel fibers (RSFs) of the closed circular shape, have different resistance mechanisms other than straight steel fibers. RSFs also maintain the same value of the orientation factor for the plane enclosed by the fiber ring perimeter. In this research, comparative studies were performed for the panels reinforced with RSFs and with straight steel fibers of $15kg/m^3$ and $30kg/m^3$, respectively. Resisting mechanisms of RSFs were identified and higher toughness indices were experimentally observed for the concrete panels reinforced with RSFs than with straight steel fibers. Orientation factor for the RSF was suggested. It was found that RSFs were more effective in increasing toughness for the panel specimens with relatively thinner thickness than beam specimens.

• Korean Journal of Mathematics
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• v.24 no.4
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• pp.737-750
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• 2016

In this note we describe some classes of rings in relation to Abelian property of factorizations by nilradicals and Jacobson radical. The ring theoretical structures are investigated for various sorts of such factor rings which occur in the process.

• Journal of the Korean Professional Engineers Association
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• v.33 no.5
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• pp.38-44
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• 2000

High Quality is requested by Consumers more and more, Accordingly, the Quality of Yarns should be followed to satisfy the Desire of Consumers. Therefore, Yarn Hairiness, which has effects on Touch, Handle, iud Dyeing, is one of important factor. In order to reduce Yarn Hairiness, various tests were made in Spinning process and the following Spinning conditions can be suggested. -. The Speed should be as lower as possible. -. Using proper Tension Disc on Winding process. -. Using Colletor on Ring Spinning process. -. Using proper Ring and Traveller :n Ring Spinning process To get the best results, continuous Trial tests should be carried-on.

• The Pure and Applied Mathematics
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• v.30 no.4
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• pp.377-395
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• 2023

The purpose of this paper is to consider the abstract theory of hypernear rings. In this regard, we derive the isomorphism theorems for hypernear rings as well as Chinese Remainder theorem. Our results can be considered as a generalization for the cases of Krasner hyperrings, near rings and rings.

• Communications of the Korean Mathematical Society
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• v.38 no.1
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• pp.97-112
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• 2023

In this paper, we introduce and study the u-S-weak global dimension u-S-w.gl.dim(R) of a commutative ring R for some multiplicative subset S of R. Moreover, the u-S-weak global dimensions of factor rings and polynomial rings are investigated.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.2
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• pp.111-118
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• 1984

On the basis of plasticity theory for porous metal, an analysis of ring compression is carried out, employing the upper bound approach. The plastic flowability and the neutral radius of porous metal ring are calculated and deformation characteristics of power forging are obtained from this result. The experiments on ring compression are carried out for sintered iron porous metal with various relative densities under various friction conditions. A good agreement is observed between the shapes of the calculated curves and the experimental results from the ring compression test. The friction factor for powder metal forming can be determined not only from the relationship between reduction in height and reduction in internal diameter but independently from the relationship between reduction in height and relative density, if the initial relative density is known.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.75-80
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• 2014

In previous study, make an attempt to estimate exhaust valve seat and seat-ring wear acceleration factor for engine durability test with measuring and consideration of wear mechanism. But found abnormal initial wear rate in exhaust valve seat-ring. And have to improve exhaust valve seat-ring wear rate for reliability reason, because next GDI/Turbo engine is based on this engine and GDI/Turbo engine have higher combustion pressure and higher thermal load. In this study, Trying to find the cause of abnormal wear factor, improve valve-train durability by change specification & design of parts and verify variant parts for improving durability of valve-train. And then I would like to propose a design guide line of valve-train system in a reliability point of view, besides make a complement of previous study.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1337-1339
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• 1998

The trench termination scheme is introduced for high voltage devices. The curvature of the depletion region at field limiting ring is critical factor to determine the breakdown voltage. The smooth curvature of the depletion junction alleviate the electric field crowding effect around this region. In the trench field limiting ring, the radius of the depletion region is smaller than conventional field limiting ring, but the distance between every trench is spaced small enough to punchthrough before initiation of local breakdown. The trench field limiting ring on silicon can ne formed by RIE followed by oxidation on side wall surface of the trench, and polysilicon filling. The combined termination of this trench floating field ring and field plate have been designed and analyzed. The breakdown simulation by 2-dimensional TCAD shows that the cylindrical junction breakdown voltage for substrate doping might be 99 percent of the ideal breakdwon voltage for substrate doping concentration of $3\times10^{14}cm^{-3}$ with about $100{\mu}m$ of lateral termination width.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.869-872
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• 2007

In this study, in order to develop low temperature sintering ultrasonic nozzle, single-layer and multilayer ring-type piezoelectric actuators were manufactured using PMN-PNN-PZT ceramics, And then the electrical properties were investigated. A ring-type piezoelectric actuator was modeled by ATILA program using finite element method(FEM). The piezoelectric actuator dimension was $\Phi26.5$ (outer diameter), $\Phi12$ (inner diameter), 3.5 mm (thickness). By FEM analysis, resonant and anti-resonant frequencies were appeared as 56.7 kHz and 61.5 kHz. The displacement increased with the increases of the number of layer. Based on the result, ring-type multilayer piezoelectric actuators were manufactured at low co-firing temperature of $940^{\circ}C$. The resonant resistance decreased with the increases of the number of layer. And also, the capacitance increased with the increases of the number of layer. The mechanical quality factor (Qm) decreased with the increases of the number of layer.

• The Korean Journal of Ecology
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• v.10 no.3
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• pp.151-159
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• 1987

Relationships between soil factors and the growth of annual ring of Pinus densiflora grown on stony mountain were investigated at two sites of the different parent rocks: the one was formed by granite at Mt. Gwanag, Seoul and the other feldspar porphyry at Mt. Bipa, Daegu. The growth of annual ring was influenced by the physical factors of soil, such as soil depth, field caacity and water content of soil, rather than by the KDICical factors, such as total nitrogen, potassium, and calcium of soil. Of the soil factors affecting the growth of annual ring, soil depth, field capacity, water content of soil and organic matter closely interrelated with each other. All of these factors influenced water content of soil which might affect the water potential of Pinus densiflora leaves. In fact, the leaf water potential, affecting as the main factor for the growth of annual ring, of the pine grown in a deep soil was higher than that of the pine in a shallow soil.