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  • Title/Summary/Keyword: fiber distribution

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Design and Fabrication of a Polarization-Independent 1 × 8 InGaAsP/InP MMI Optical Splitter (편광에 무관한 1 × 8 InGaAsP/InP 다중모드간섭 광분배기의 설계 및 제작)

  • Yu, Jae-Su;Moon, Jeong-Yi;Bae, Seong-Ju;Lee, Yong-Tak
    • Proceedings of the Optical Society of Korea Conference
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    • 2000.08a
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    • pp.28-29
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    • 2000
  • Optical power splitters and/or couplers are important components for optical signal distribution between channels both in wavelength division multiplexing(WDM) systems and photonic integrated circuits(PICs). Since polarization is usually not known after propagation in an optical fiber, passive WDM components have to be polarization insensitivity, Compared to alternatives such as directional couplers or Y-junction splitters, splitters based on multimode interference(MMI) have found a growing interest in recent yens because of their desirable characteristics, such as compact size, low excess loss, wide bandwidth, polarization independence, and relaxed fabrication tolerances(1) . These devices have been fabricated in polymers, silica, or III-V semiconductor materials. A1 × 4 MMI power splitter on InP materials that were suitable for application in the 1.55-{\mu}{\textrm}{m} region(2) . However, the fabrication process of the structure is too complicated and the photolithography tolerance is very tight. Also, a 1 × 16 InGaAsP/InP MMI power splitter with an excess loss of 2.2dB and a splitting ratio of 1.5dB was demonstrated by using deep etching(3) . The deep etching of the sidewalls through the entire guide layer of the slab waveguide resulted in a number of drawbacks(4) . (omitted)

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The Effect of Circulat Hole Size and Distribution on Strength of Braided Composite (브레이드 복합재료의 원공의 크기와 분포가 재료강도에 미치는 영향)

  • Lee, Gyeong-U;Gang, Tae-Jin
    • Korean Journal of Materials Research
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    • v.4 no.3
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    • pp.253-258
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    • 1994
  • The effect of hole size and hole-to-hole distance in the braided and laminated composite was studied in terms of tensile strength, pin bearing strength, and flexural strength of S2-glass fiber braided polyester. The tensile strength reduction with hole size was well fitted with he Whitney and Nuismer's prediction for the laminated composite. The characteristic distance was measured to be about 1.6mm for braided composite and 1.8mm for laminated one. The effect of distance between the centers of two circu lar holes on tensile strength was negligible when the distance between these two holes was larger than 4 times of the diameter of circular hole for both braided and laminated composite. The side effect was diminished when the center of hole was located 3 times farther than the diamet.er of the hole. The pin bearing strengths was decreased with the size of pin hole for both braided and laminated composite.

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A Study on Mode I Interlaminar Fracture Toughness of Hybrid Composites (하이브리드 복합재료의 모드 I 층간파괴인성치에 관한 연구)

  • 김형진;곽대원;김재동;고성위
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.39 no.4
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    • pp.262-268
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    • 2003
  • This paper describes the effect of loading rate, specimen geometries and material properties for Mode I interlaminar fracture toughness of hybrid composite by using double cantilever beam (DCB) specimen. In the range of loading rate 0.2-20mm/min, there is found to be no significant effect of loading rate with the value of critical energy release rate (G_IC). The value of GIC for variation of initial crack length are nearly similar values when material properties are CF/CF and GF/GF, however, the value of GIC/ are highest with the increasing initial crack length at CF/GF. The SEM photographs show good fiber distribution and interfacial bonding of hybrid composites when the moulding is the CF/GF

Effects of Blend Ratio and Heat Treatment on the Properties of the Electrospun Poly(ethylene terephthlate) Nonwovens

  • Kim Kwan Woo;Lee Keun Hyung;Lee Bong Seok;Ho Yo Seung;Oh Seung Jin;Kim Hak Yong
    • Fibers and Polymers
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    • v.6 no.2
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    • pp.121-126
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    • 2005
  • Semicrystalline poly(ethylene terephthalate) (cPET)/amorphous poly(ethylene terephthalate) with isophthalic acid (aPET) blends with 100/0, 75/25, 50/50, 25/75, and 0/100 by weight ratios were dissolved in a mixture of trifluoroacetic acid (TFA)/methylene chloride (MC) (50/50, v/v) and electrospun via the electrospinning technique. Solution properties such as solution viscosity, surface tension and electric conductivity were determined. The solution viscosity slightly decreased as aPET content increased, while there was no difference in surface tension with respect to aPET composition. The characteristics of the electro spun cPET/aPET blend nonwovens were investigated in terms of their morphology, pore size and gas permeability. All these measurements were carried out before and after heat treatment for various blend weight ratios. The average diameter of the fibers decreased with increasing aPET composition due to the decrease in viscosity. Also, the morphology of the electrospun cPET/aPET blend nonwovens was changed by heat treatment. The pore size and pore size distribution varied greatly from a few nanometers to a few microns. The gas permeability after heat treatment was lower than that before heat treatment because of the change of the morphology.

Identification keys of Jeonho(Qianhu) and Asam(Eshen) (백화전호(白花前胡)와 자화전호(紫花前胡), 아삼(峨參)의 감별기준(鑑別基準))

  • Lee, Guem-San;Doh, Eui-Jeong;Jeong, Seung-Il;Kim, Hong-Jun;Lee, Jang-Chun;Oh, Seung-Eun;Ju, Young-Sung;Cho, Su-In
    • The Korea Journal of Herbology
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    • v.26 no.3
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    • pp.57-63
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    • 2011
  • Objectives : Peucedani Radix ('Jeonho' in Korean) is the root of Peucedanum praeruptorum or Angelica decursiva. However, the root of Anthriscus sylvestris has usually been distributed as Jeonho. This study was performed to determine the discriminative criteria of Jeonho, focused on distribution in Korean markets. Methods : We have determined identification keys to discriminate each Jeonho samples, through observation of external morphology of original plants, and the research of external and internal morphological features of dried Jeonho herbs. Results : Because of identical to the Korean plant name 'Jeonho', Anthrisci Radix had been came into use as a substitute of Jeonho in Korea during the time of Japanese colonial rule. The original plants of Jeonho and its substitute are discriminated with shape of leaf, leaf margin and color of stem. External morphological features of the medicinal herbs of Jeonho are different in the color of cross-sections, pellucid dot, white powder. Internal morphological points, such as fiber bundle of xylem, seconadary mudullary ray and ray of xylem were also used as discriminative criteria for Jeonho. Further details(e.g. identificaion keys) are in the article. Conclusions : We think that these discriminative criteria will be meaningful in identifying the substitutes and adulterants of Jeonho.

Comparison of Interfacial Aspects of Carbon and Glass Fibers/Epoxy Composites by Microdroplet Tests at Low and Room Temperatures (상온 및 저온에서의 탄소와 유리섬유/에폭시 복합재료의 계면특성 비교)

  • Wang, Zuo-Jia;GnidaKouong, Joel;Kim, Myung-Soo;Park, Joung-Man;Um, Moon-Kwang
    • Journal of Adhesion and Interface
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    • v.10 no.4
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    • pp.162-168
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    • 2009
  • As a preliminary study of optimum composite properties under cryogenic temperature, the comparison of interfacial properties of carbon or glass fibers reinforced epoxy composites was evaluated at ambient and intermediate low temperature, i.e., 25 and 10C by using micromechanical techniques. Under tensile and compressive loading conditions, their mechanical modulus at low temperature was higher than that atambient temperature. Interfacial shear strength (IFSS) at ambient and low temperatures was compared to each other, depending on epoxy matrix toughness and apparent modulus at the interface. The IFSS was much higher at low temperature than that at room temperature because of the increased epoxy matrix modulus. Statistical distributions of tensile strengths of glass and carbon fibers were evaluated for different temperature ranges, which is dependent upon fiber's inherent flaws and rigidity.

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The study on the TH(tyrosine hydroxylase) immunoreactive cells in forebrain of developing mongolian gerbil (발달중인 Mongolian gerbil의 전뇌에서 TH 면역반응세포의 분포에 관한 연구)

  • Lee, Kyoung-youl;park, Il-kwon;Kwon, Hyo-jung;Park, Mi-sun;Song, Chi-won;Kim, Moo-kang;Chang, Kyu-tae;Lee, Kang-iee;Kim, Won-sik;Park, Won-hark
    • Korean Journal of Veterinary Research
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    • v.41 no.2
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    • pp.147-155
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    • 2001
  • The immunocytochemical localization of tyrosine hydroxylase(TH) is examined in the developmental forebrain of mongolian gerbil in order to determine changes in the distribution and cytology of neurons. At each of the different developmental stage, including prenatal(E)14, E16, E18, E20, postnatal(P)0, P2, P4 days, mongolian gerbils were sacrificed. In E14, TH-IR cells were predominantly round or oval in shape and their processes were very short. In olfactory blub, TH-IR cells were begun to appear from E20. In the striatum, we observed only fibers of TH-IR at all ages. From E16, TH-IR perikarya and fiber were present in periventricular nucleus and paraventricular nucleus of hypothalamus. The changes from the early to the late prenatal stages of development appear to be the result of an increase in number of TH-IR perikarya and processes. These results were shown slight differences to other rodents.

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Repair of Pre-cracked Reinforced Concrete (RC) Beams with Openings Strengthened Using FRP Sheets Under Sustained Load

  • Osman, Bashir H.;Wu, Erjun;Ji, Bohai;Abdulhameed, Suhaib S.
    • International Journal of Concrete Structures and Materials
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    • v.11 no.1
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    • pp.171-183
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    • 2017
  • Strengthening reinforced concrete (RC) beams with openings by using aramid fiber reinforcement polymers (AFRP) on the beams' surfaces offers a useful solution for upgrading concrete structures to carry heavy loads. This paper presents a repairing technique of the AFRP sheets that effectively strengthens RC beams, controls both the failure modes and the stress distribution around the beam chords and enhances the serviceability (deflection produced under working loads be sufficiently small and cracking be controlled) of pre-cracked RC beams with openings. To investigate the possible damage that was caused by the service load and to simulate the structure behavior in the site, a comprehensive experimental study was performed. Two unstrengthened control beams, four beams that were pre-cracked before the application of the AFRP sheets and one beam that was strengthened without pre-cracking were tested. Cracking was first induced, followed by repair using various orientations of AFRP sheets, and then the beams were tested to failure. This load was kept constant during the strengthening process. The results show that both the preexisting damage level and the FRP orientation have a significant effect on strengthening effectiveness and failure mode. All of the strengthened specimens exhibited higher capacities with capacity enhancements ranging from 21.8 to 66.4%, and the crack width reduced by 25.6-82.7% at failure load compared to the control beam. Finally, the authors present a comparison between the experimental results and the predictions using the ACI 440.2R-08 guidelines.

Performance of Reinforced Concrete Beams Strengthened with Bi-directional CFRP Strips (이 방향 탄소섬유 스트립을 사용하여 보강된 콘크리트 보의 거동에 대한 연구)

  • Kim, Changhyuk
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.6
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    • pp.30-36
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    • 2018
  • Researches on strengthening and rehabilitation are important since structural capacity is degraded by deterioration or damage of structural members. An effective strengthening scheme such as an externally bonded Carbon Fiber Reinforced Polymers (CFRP) can improve the structural performance of a concrete structure in a cost-effective way. Therefore, many experimental studies on strengthening methods have been widely carried out. In regards to the shear strengthening of a concrete beam, variables of the experimental studies were the amount of CFRP, the angle of the strip, the width of the strip, and the interaction between the materials. However, there are insufficient researches on bi-directional CFRP layout compared to the previous researches. In this study, a total of ten concrete beams were designed and tested to evaluate the shear strengthening effect using CFRP strips. The effectiveness of strengthening was investigated based on the shear contribution of materials, strain distribution of stirrup, and the maximum shear capacity of specimens.

Micropore Analysis and Adsorption Characteristics of Activated Carbon Fibers (활성탄소섬유의 미세기공 분석 및 흡착특성)

  • Moon, Dong-Cheul;Lee, Kwang-Ho;Kim, Chang-Soo;Kim, Do-Hyung;Kim, Mi-Ran;Shin, Chae-Ho;Park, II-Young;Nam, Seoung-Youl;Lee, Chang-Gi
    • Analytical Science and Technology
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    • v.13 no.1
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    • pp.89-95
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    • 2000
  • Three grades of activated carbon fibers (ACFs) were prepared from various precursors of plantic, synthetic, and mixed fabrics of viscose rayon and cotton. The ACFs an exhibited type I isotherms on the adsorption of nitrogen or argon. Micropore analysis revealed that the ACFs have uniform micropore size distribution in which their peak diameters were in the range of 5.6±0.3\AA. The BET surface area of ACFs up to 1600m2g1 was proportional to the adsorption capacity of iodine. The BET values of the ACFs prepared were proportional to the burn-off degree of the products.

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