• Title/Summary/Keyword: 강선의 종류

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A Study of shear bond strength of bonded retainer according to the bonding method and type of wires (접착방법 및 multistranded wire의 종류에 따른 접착식 보정장치의 전단접착강도에 관한 연구)

  • Lee, Hyoung-Cheol;Son, Woo-Sung
    • The korean journal of orthodontics
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    • v.32 no.2 s.91
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    • pp.143-153
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    • 2002
  • The bonded orthodontic retainer constructed from composite and multistrand orthodontic wire provides an esthetic and efficient system for maintained retention. This study was designed to measure shear bond strength of bonded retainers and to suggest a optimal combination of a multistrand wire and bonding method used when bonded retainer was fabricated. 160 sound maxillary and mandibular premolars were used for 80 test samples. After Uniformizing bonding area, length of wire, and thickness of composite, multistrand wire was bonded to fabricated a bonded retainer by direct or indirect bonding method. Shear bond strength and extension length of each sample were measured by a universal testing machine. The results of this study were as follows : 1. In vitro shear bond testing found 6-stranded, 0.0155 inch wires to have the largest shear bond strength and 3-stranded, 0.0195 inch wires to have the least shear bond strength. But, These difference was not statistically significant(p<0.05). 2. In vitro extension testing found 3-stranded, 0.0155 inch wires to have the largest extension length and 3-stranded, 0.0195 inch wires to have the least extension length(p<0.05). The larger diameter wire was used, the larger extension length was shown. But, the strand of wire is not related to the extension length of wire. 3. In comparison with direct bonding method, larger shear bond strength and extension length was shown in indirect bonding method(p<0.05).

Load Transfer of Tension and Compression Anchors in Weathered Soil (인장형 앵커와 압축형 앵커의 하중전이에 관한 연구)

  • 김낙경
    • Journal of the Korean Geotechnical Society
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    • v.17 no.3
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    • pp.59-68
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    • 2001
  • 풍화토 지반에 설치된 그라운드 앵커의 하중전이 현상을 규명하기 위하여 성균관대학교 지반시험장에서 인발시험을 수행하였다. 지반과 구조물을 일체화시키는데 사용하는 앵커는 앵커체와 지반의 마찰력에 의해서 구조물을 지지하는 역할을 하며 앵커의 하중과 변형의 관계를 규명하기 위해서는 앵커의 마찰력 분포의 변화(하중전이)가 중요한 요소가 된다. 하중 재하시 앵커체에 발생하는 하중전이 분포는 앵커의 인발 지지력과 밀접한 관계가 있고 앵커체의 종류(인장형 또는 압축형), 정착장의 길이, 지반 조건 등에 따라 분포 양상이 변하기 때문에 하중전이를 이해하기 위해서는 강선과 그라우트의 하중분포 그리고 앵커 그라우트체와 지반과의 마찰력 분포를 알아야 한다. 앵커의 자유장의 강선에 작용하는 응력, 그라우트체에 작용하는 응력, 그리고 정착장 강선의 응력을 계측하여 강선과 그라우트의 정착응력 및 그라우트와 지반에서의 마찰력 분포를 구함으로써 강선-그라우트-지반의 복합적인 거동에 따른 각 하중 단계마다의 하중전이 분포를 구하였다. 또한 현장시험 결과의 신뢰성 확보를 위하여 수치해석 모델링을 통하여 해석을 수행하여 비교하였다.

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Histological and Histochemical Studies on the Cutaneous Mucous Glands According to the Development of Frog, Rana nigromaculata (개구리(Rana nigromaculata)발생에 따른 피부점액선의 조직학적 및 조직화학적 연구)

  • Kim, Han-Hwa;Noh, Yong-Tai;Chung, Young-Wha
    • The Korean Journal of Zoology
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    • v.18 no.2
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    • pp.51-60
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    • 1975
  • The present study was performed histologically and histochemically to observe the cutaneous mucous glands in the frog, Rana nigromaculata during metamorphosis. The cutaneous thssues including dermal plicae in the dorsal portions of the frog tadpoles at each metamorphosis stage were fixed in 10% buffered formalin at$4^{\circ}C$, embedded in paraffin wax, sectioned 4 $\mu$m thickness and stained with periodic acid-Schiff(PAS) and alcian blue (AB) at both pH 2.5 and pH 1.0. The results of observation were as follows: 1. The developments of cutaneous mucous glands of the frog tadpole were begun with appearance of gland cell nest in the dermis at metamorphosis XV stage and significant numerical increases could be seen at metamorphosis XX, XXIII and XXIV stages. 2. This cutaneous mucous gland of the frog tadpole could be divided into two types; A-type glands showed strong positivities to both PAS and AB at pH 2.5 in the gland body cells and to PAS in the gland neck cells, and B-type glands at AB pH 2.5 in the gland body cells. 3. In the A-type mucous glands, the reactivities of the glandular epithelial cells to both PAS and AB stain could be first seen at the metamorphosis XIX stage of frog tadpole. The reactivities of the glandular epithelial cells to both PAS and AB pH 2.5 were gradually increased according to the process of metamorphosis after XX stage of metamorphosis. 4. The B-type mucous glands were first seen at the XX stage and the reactivity of the glandular epithelial cells to AB at pH 2.5 was gradually increased according to the process of metamorphosis after XX stage. 5. The A-type and the B-type mucous glands were in the ratio of 99 : 1, 7 : 3 and 5.5 : 4.5 for each of metamorphosis XX, XXI-XXII and XXIII-XXV stages. 6. The remarkable development of the cutaneous mucous glands of the frog tadpoles might be needed to maintain water and electrolyte balances according to the change of way from aquatic life to amphibious.

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Effect of Reinforcing Fiber Types on Lap Splice Performance of High Performance Fiber Reinforced Cementitious Composite(HPFRCC) (보강 섬유 종류에 따른 고인성 시멘트 복합체내에서 철근의 겹침 이음 성능)

  • Jeon, Esther;Yun, Hyun-Do
    • Journal of the Korea Concrete Institute
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    • v.19 no.2
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    • pp.153-161
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    • 2007
  • This paper investigates the lap splice performance of structural steel bars embedded in high performance fiber reinforced cementitious composite(HPFRCC) with various matrix ductilities. Matrix ductility is governed fiber type and fiber volume fraction. Fiber types were polypropylene(PP), polyethylene(PE) and hybrid fiber[polyethylene fiber+steel cord(PE+SC)]. The lap splice length$(l_d)$ was calculated according to the relevant ACI code requirements for reinforcing bars in normal concrete. As the result of tests, lap splice strength of HPFRCC using PE1.5 and hybrid fiber increased by up to $82{\sim}91$ percent more than that of concrete. Splice strength and energy absorption capacity of PE0.75+SC0.75 or PE1.5(fiber volume fraction 1.5%) specimen increased more than that of PP2.0(fiber volume fraction 2.0%) specimen. Therefore lap splice performance depends on fiber tensile strength and Young's modulus more than fiber volume fraction. Also, HPFRCC appear multiple crack and ductile postpeak behavior due to bridging of fiber in cementitious composite.

The Intensity Scale of Multiple Scattering of X-rays in Non-Crystalline Solids (비정질 고체에 대한 X선의 다중 산란 강도)

  • 박성수;장윤식;류봉기;박희찬
    • Journal of the Korean Ceramic Society
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    • v.34 no.1
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    • pp.109-113
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    • 1997
  • When the intensity of X-rays scattered from amorphous materials (very weakly absorbing materials) is measured using standard diffractometric technique, the intensity caused by multiple scattering is obtained in the measured X-ray intensity. Computer programs have been developed to estimate the intensity of the mul-tiple scattering obtained in vitreous SiO2 and B2O3 with various X-rays. Using the above computer program, the intensity ratios of multiple scattering to single scattering in vitreous SiO2 were 0.10~0.16% at CuK$\alpha$, 0.98~5.87% at MoK$\alpha$, and 1.88~17.86% at AgK$\alpha$ in the range of 2$\theta$=0~180$^{\circ}$. Therefore, pri-or to the structural analysis of vitreous SiO2 and B2O3 performed experimentally using X-ray diffractometric technique, the intensity data measured in MoK$\alpha$ and AgK$\alpha$ radiations must be corrected for multiple scattering effect.

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Manufacturing of High-Strength and High-Ductility Pearlitic Steel Wires Using Noncircular Drawing Sequence (비원형 신선을 이용한 고강도-고연성 펄라이트 강선의 제조)

  • Baek, Hyun Moo;Hwang, Sun Kwang;Joo, Ho Seon;Im, Yong-Taek;Son, Il-Heon;Bae, Chul Min
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.7
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    • pp.743-749
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    • 2014
  • In this study, a noncircular drawing (NCD) sequence for manufacturing high-strength and high-ductility pearlitic steel wires was investigated. Multipass NCD was conducted up to the 12th pass at room temperature with two processing routes (defined as the NCDA and NCDB), and compared with the wire drawing (WD). During the torsion test, delamination fracture in the drawn wire was observed in the 10th pass of the WD whereas it was not observed until the 12th pass of the NCDB. From X-ray diffraction, the circular texture component that increases the likelihood of delamination fracture of the drawn wire was rarely observed in the NCDB. Thus, the improved ability of the multipass NCDB to manufacture high-strength pearlitic steel wires with high torsional ductility compared to the WD (by reducing the likelihood of delamination fracture) was demonstrated.

An experimental study of dynamic frictional resistance between orthodontic bracket and arch wire (교정용 브라켓과 강선 사이의 운동마찰저항력에 관한 실험적 연구)

  • Lee, Jae-Hwan;Lee, Ki-Soo
    • The korean journal of orthodontics
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    • v.31 no.4 s.87
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    • pp.467-477
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    • 2001
  • This investigation was designed to determine the effects of wire size, bracket width and the number of bracket on bracket-wire dynamic frictional resistance during simulating arch wire-guided tooth movement in vitro. For simulation of an arch wire-guided tooth movement, we simulated tooth, periodontal ligament and cancellous bone. Maxillary premolar and 1st molar were simulated as real sized resin teeth, the simulated resin teeth which its root was coated by polyether impression material which its elastic modulus is similar to periodontal ligament were embedded in steel housing with inlay wax which its elastic modulus is similar to cancellous bone. Stainless steel wires in four wire size (0.016, 0.018, $0.016\;{\times}\;0.022,\;0.019\;{\times}\;0.025$ inch) were examined with respect to three (stainless steel) bracket widths (2.4, 3.0, 4.3mm) and the number of medium bracket(one, two, three) included in the experimental assembly under dry condition. The wires were ligated into the brackets with elastomeric module. The results were as follows : 1. In all the brackets, frictional resistance increased with increase in wire size. But, statistically similar levels of frictional resistance were observed between 0.018 inch and $0.016\;{\times}\;0.022$ inch wires in narrow bracket and also between 0.016 inch and 0.018 inch wire in wide backet. 2. The frictional forces produced by 0.016 inch wire were statistically similar levels in all the brackets. In 0.018 inch round wire, wide bracket was associated with lower amounts of friction than both narrow and medium brackets. In $0.016\;{\times}\;0.022,\;0.019\;{\times}\;0.025$ inch rectangular wire, wide bracket produced target friction than both narrow and medium brackets. In all the wirer, narrow and medium bracket demonstrated no statistical difference in levels of frictional resistance. 3. Frictional resistance increased with increase In number of medium bracket. 0.016 inch round wire demonstrated the greatest increment in frictional resistance, followed by $0.019\;{\times}\;0.025,\;0.016\;{\times}\;0.022$ inch rectangular wire which were similar level in increment of frictional resistance, 0.018 inch wire demonstrated the least increment. The increments of frictional resistance were not constantly direct proportion to number of bracket.

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