• International Journal of Concrete Structures and Materials
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• 제3권2호
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• pp.119-126
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• 2009

This paper provides a brief summary of the performance of an innovative slip hardening twisted steel fiber in comparison with other fibers including straight steel smooth fiber, high strength steel hooked fiber, SPECTRA (high molecular weight polyethylene) fiber and PVA fiber. First the pull-out of a single fiber is compared under static loading conditions, and slip rate-sensitivity is evaluated. The unique large slip capacity of T-fiber during pullout is based on its untwisting fiber pullout mechanism, which leads to high equivalent bond strength and composites with high ductility. Due to this large slip capacity a smaller amount of T-fibers is needed to obtain strain hardening tensile behavior of fiber reinforced cementitious composites. Second, the performance of different composites using T-fibers and other fibers subjected to tensile and flexural loadings is described and compared. Third, strain rate effect on the behavior of composites reinforced with different types and amounts of fibers is presented to clarify the potential application of HPFRCC for seismic, impact and blast loadings.

• 대한수학회보
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• 제57권1호
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• pp.1-30
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• 2020

In this paper, we classify all twisted torus knots which are middle/hyper doubly Seifert. By the definition of middle/hyper doubly Seifert knots, these knots admit Dehn surgery yielding either Seifert-fibered spaces or graph manifolds at a surface slope. We show that middle/hyper doubly Seifert twisted torus knots admit the latter, that is, non-Seifert-fibered graph manifolds whose decomposing pieces consist of two Seifert-fibered spaces over the disk with two exceptional fibers.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권2호
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• pp.55-62
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• 2005

The optical CT was developed to use twisted fibers for 170 kV GIS. The fiber sensor optimized on the optical CT was wound 3 turns and twisted 4 times per a turn at the pipe with a diameter of 130 mm. The measurement error for the linearity which was satisfied the criterion of 'IEC Class-1.0' was less than ± 0.44 % at the transmission type and ± 0.82 % at the reflection type to 2,000 A. At a low current to 200 A, the measurement error was ± 0.69% at the transmission type and ± 1.38 % at the reflection type.

• 대한수학회보
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• 제53권1호
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• pp.273-301
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• 2016

In this paper, we classify all twisted torus knots which are doubly middle Seifert-fibered. Also we show that all of these knots possibly except a few admit Dehn surgery producing a non-Seifert-fibered graph manifold which consists of two Seifert-fibered spaces over the disk with two exceptional fibers, glued together along their boundaries. This provides another infinite family of knots in $S^3$ admitting Dehn surgery yielding such manifolds as done in [5].

• 호남수학학술지
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• 제40권3호
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• pp.591-600
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• 2018

In [4] Miyazaki and Motegi constructed one family of knots in $S^3$ which admits Dehn surgery producing a Seifert-fibered space over $S^2$ with four exceptional fibers. On the other hand, in [3] using doubly hyper Seifert twisted torus knots, the author constructed six families of knots in $S^3$ which admit Dehn surgery yielding a Seifert-fibered space over $S^2$ with four exceptional fibers. It is questioned in [3] whether or not the family of the knots constructed in [4] belongs to one of the six families of the knots in [3]. In this paper, we give the positive answer for this question.

• 대한수학회보
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• 제52권1호
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• pp.313-321
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• 2015

In this paper, we construct infinite families of knots in $S^3$ which admit Dehn surgery producing a Seifert-fibered space over $S^2$ with four exceptional fibers. Also we show that these knots are turned out to be satellite knots, which supports the conjecture that no hyperbolic knot in $S^3$ admits a Seifert-fibered space over $S^2$ with four exceptional fibers as Dehn surgery.

• 한국잠사곤충학회지
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• 제41권3호
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• pp.201-204
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• 1999

The silk/paper mulberry paper was prepared by recycling of the hard twisted silk waste and its mechanical properties was investigated. The silk waste was pretreated with sodium hydroxide(0.5%) and sodium carbonate(4%) to make it easy for beating and fibrillation. The silk/paper mulberry hand sheet paper has better mechanical properties of tearing strength and air permeability compared with the traditional and modified traditional paper. Treating with alkaline solution, the hard twisted silk waste could be used for an novel composite material.

• Carbon letters
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• 제13권4호
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• pp.191-204
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• 2012

Carbon nanotubes (CNTs) have exceptional mechanical, electrical, and thermal properties compared with those of commercialized high-performance fibers. For use in the form of fabrics that can maintain such properties, individual CNTs should be held together in fibers or made into yarns twisted out of the fibers. Typical methods that are used for such purposes include (a) surfactant-based coagulation spinning, which injects a polymeric binder between CNTs to form fibers; (b) liquid-crystalline spinning, which uses the nature of CNTs to form liquid crystals under certain conditions; (c) direct spinning, which can produce CNT fibers or yarns at the same time as synthesis by introducing a carbon source into a vertical furnace; and (d) forest spinning, which draws and twists CNTs grown vertically on a substrate. However, it is difficult for those CNT fibers to express the excellent properties of individual CNTs as they are. As solutions to this problem, post-treatment processes are under development for improving the production process of CNT fibers or enhancing their properties. This paper discusses the recent methods of fabricating CNT fibers and examines some post-treatment processes for property enhancement and their applications.

• 콘크리트학회논문집
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• 제22권4호
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• pp.575-583
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• 2010

이 연구는 비틀림 강섬유(T- 섬유) 의 비틀림 횟수가 인발거동과 T- 섬유를 사용한 고성능 섬유보강 시멘트 복합재료의 인장거동에 미치는 영향을 조사하였다. T- 섬유의 여러 인자와 비틀림 횟수가 섬유의 인발거동에 미치는 영향을 해석적으로 조사하고, 최대의 인발에너지를 생성할 수 있는 비틀림 횟수를 조사하였다. 이와 더불어 T- 섬유의 인발시험과 인장시험을 수행하여, 비틀림 횟수가 고인성 섬유보강 시멘트 복합재료의 인장거동에 미치는 영향을 조사하였다. 비틀림 횟수가 6ribs/30 mm인 T(L)- 섬유와 비틀림 횟수가 18ribs/30 mm인 T(H)- 섬유를 사용하였다. T(H)- 섬유는 인발시험시 섬유의 파단되어, T(L)- 섬유보다 높은 인발응력을 유발했음에도 불구하고 낮은 총 인발에너지를 생성하였다. 이러한 인발 시험서의 결과는 인장 거동에도 분명하게 반영되었다. T(L)- 섬유를 사용한 고인성 섬유보강 시멘트 복합재료의 경우, T(H)- 섬유의 사용시보다, 우수한 변형능력과 에너지 흡수능력, 그리고 미세균열 거동을 보였다.

• Applied Microscopy
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• 제28권2호
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• pp.127-137
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• 1998

This study was observed of the skin that changed after irradiation of the ultraviolet A. All the mouse were hairless which the weight are about 25g and the ages $6\sim8$ weeks old. The mouse were divided into six groups; control, irradiated for 6 hours, 3 days, 7 days, 14 days, 21 days and 28 days. Each group was irradiated with ultraviolet that is $320nm\sim366nm$ of wavelengths. After irradiated, the skin was observed with the electron microscope and the light microscope. The results are as follow: 1) Light microscopy With following irradiation, the epidermis was not changed to most groups but at the 28 days group was thickened and deposit the melanocyte. The elastic fibers within the epidermis were thickened and twisted with following irradiation. 2) Eelectron microscopy The elastic fibers were slightly clumped at 6 hours group, mildly increased and partly aggregated in the 3 days group, branched and tangled at 7 days group, irregulated and electron density at 14 days group, sightly thickened and twisted at 21 days group, and randomly arranged, shortened, twisted, and electron density at 28 days group.