• Title/Summary/Keyword: Thin-walled

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Effects of Composite Couplings on Hub Loads of Hingeless Rotor Blade (무힌지 로터 블레이드의 허브하중에 대한 복합재료 연성거동 연구)

  • Lee, Ju-Young;Jung, Sung-Nam
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.7
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    • pp.29-36
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    • 2004
  • In this work, the effect of composite couplings on hub loads of a hingeless rotor in forward flight is investigated. The hingeless composite rotor blade is idealized as a laminated thin-walled box-beam. The nonclassical effects such as transverse shear, torsional warping are considered in the structural formulation. The nonlinear differential equations of motion are obtained by applying Hamilton's principle. The blade response and hub loads are calculated using a finite element formulation in space and time. The aerodynamic forces acting on the blade are calculated by quasi-steady strip theory. The theory includes the effects of reversed flow and compressibility. The magnitude of elastic couplings obtained by MSC/NASTRAN is compared with the classical pitch-flap $({\delta}3)$ or $pitch-lag({\alpha}1)$ coupling. It is found that the elastic couplings have a substantial effect on the behavior of $N_b/rev$ hub loads. Nearly 10 to 40% of hub loads is reduced by appropriately tailoring the fiber orientation angles in the laminae of the composite blade.

The behaviour of a new type of connection system for light-weight steel structures applied to roof trusses

  • Kaitila, Olli;Kesti, Jyrki;Makelainen, Pentti
    • Steel and Composite Structures
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    • v.1 no.1
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    • pp.17-32
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    • 2001
  • The Rosette-joining system is a completely new press-joining method for cold-formed steel structures. One Rosette-joint has a shear capacity equal to that of approximately four screws or rivets. The Rosette thin-walled steel truss system presents a new fully integrated prefabricated alternative to light-weight roof truss structures. The trusses are built up on special industrial production lines from modified top hat sections used as top and bottom chords and channel sections used as webs which are joined together with the Rosette press-joining technique to form a completed structure easy to transport and install. A single web section is used when sufficient but can be strengthened by double-nesting two separate sections or by using two lateral profiles where greater compressive axial forces are met. An individual joint in the truss can be strengthened by introducing a hollow bolt into the joint hole. The bolt gives the connection capacity a boost of approximately 20%. A series of laboratory tests have been carried out in order to verify the Rosette truss system in practice. In addition to compression tests on individual sections of different lengths, tests have also been done on small structural assemblies and on actual full-scale trusses of a span of 10 metres. Design calculations have been performed on selected roof truss geometries based on the test results, FE-analysis and on the Eurocode 3 and U.S.(AISI) design codes.

A Development of Detail Design Software for Conventional Catenary System (기존선 전차선로 상세설계 소프트웨어 개발)

  • Lee, Ki-Won;Kwon, Sam-Young;Cho, YongHyeon;Lee, Tae-Kwon;Lee, Kyung-Hoon
    • Proceedings of the KSR Conference
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    • 2008.06a
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    • pp.481-488
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    • 2008
  • A detail design of overhead catenary system can be divided into a pegging plan and a design of MD(mounting diagram). In the pegging plan, the mast location, staggering and tension length are determined in the longitudinal point of view according to track condition, location of substation and etc. In the MD, a transversal diagram including masts, all of wires, cantilever, foundation and etc. and materials used are shown. This study presents a development of a software to design the MD for a conventional catenary system automatically. In the program, thin walled steel pole, foundation, cantilever, all of wires and etc. are automatically drawn according to the input and catenary conditions. And materials used in the MD and the section can be also managed respectively in the program. This application of the program is developed using C# for input/calculating and using C++(ObjectARX) for drafting the MD, respectively.

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Effect of Ti and Si Interlayer Materials on the Joining of SiC Ceramics

  • Jung, Yang-Il;Park, Jung-Hwan;Kim, Hyun-Gil;Park, Dong-Jun;Park, Jeong-Yong;Kim, Weon-Ju
    • Nuclear Engineering and Technology
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    • v.48 no.4
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    • pp.1009-1014
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    • 2016
  • SiC-based ceramic composites are currently being considered for use in fuel cladding tubes in light-water reactors. The joining of SiC ceramics in a hermetic seal is required for the development of ceramic-based fuel cladding tubes. In this study, SiC monoliths were diffusion bonded using a Ti foil interlayer and additional Si powder. In the joining process, a very low uniaxial pressure of ~0.1 MPa was applied, so the process is applicable for joining thin-walled long tubes. The joining strength depended strongly on the type of SiC material. Reaction-bonded SiC (RB-SiC) showed a higher joining strength than sintered SiC because the diffusion reaction of Si was promoted in the former. The joining strength of sintered SiC was increased by the addition of Si at the Ti interlayer to play the role of the free Si in RB-SiC. The maximum joint strength obtained under torsional stress was ~100 MPa. The joint interface consisted of $TiSi_2$, $Ti_3SiC_2$, and SiC phases formed by a diffusion reaction of Ti and Si.

Segmental Aplasia of the Right Uterine Horn in a Primiparous Holstein Cow (홀스타인 초산우에서 우측 자궁각의 부분무형성 일례)

  • Kim, Ill-Hwa;Kang, Hyun-Gu;Hur, Tai-Young;Lee, Hae-Rim;Mo, In-Pil
    • Journal of Veterinary Clinics
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    • v.29 no.5
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    • pp.427-430
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    • 2012
  • An infertile, three-year-old primiparous cow was diagnosed preliminarily with pyometra by rectal palpation at 180 days postpartum. Ultrasonography showed that the cranial portion of the right uterine horn was distended with fluid, while the base portion of the horn was missing. A dense band of tissue connected the cranial portion of the uterine horn to the uterine body. However, the left uterine horn was normal. Gross postmortem analysis of the reproductive organs confirmed the ultrasonographic observations. Histopathological observations also showed that dark red-brown mucus filled the thin-walled right uterine horn, where neither caruncles nor uterine glands were observed. Finally, this primiparous Holstein cow was diagnosed with segmental aplasia of the right uterine horn.

Bond Behavior of Thin-Walled Rectangular Profiled Steel Sheet Concrete Short Columns (절곡된 단면을 갖는 얇은 판요소 콘크리트 충전 각형강관 기둥의 부착거동)

  • Yun, Hyun-Do;Park, Wan-Shin;Han, Byung-Chan
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.9 no.1
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    • pp.233-241
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    • 2005
  • The paper is presented experimental study results on bond stress between profiled steel and concrete in Profiled SPC(Profiled Steel Plate Concrete) rectangular steel tubes through an experimental program in which 13 pull-out specimens were tested. Advantages and class of composite members and current problems of construction work are noted, past research of PSSC is described. An experimental study is described and evaluated. The bond capacity is interrelated with slip at the steel concrete interface. The factors influencing the mechanism of bond stress transfer were the cross section shape, length/diameter, diameter/thickness and environmental parameters (temperature, moisture). The results of experimental program indicated that the force transfer could be characterized into two regions The first region was governed by bond with no relative slip between the profiled steel and concrete. The second region occurs after the chemical debonding. Bond stress transfer in this region was governed by frictional resistance between profiled steel and concrete and cross section shapes. The important factors influencing the magnitude of frictional resistance are the profiled steel shapes, length/diameter and environmental parameters. (temperature, moisture)

TREATMENT OF MUCOCELE USING THE $CO_2$ LASER : CASE REPORT ($CO_2$ Laser를 이용한 점액종의 치료)

  • Lee, In-Cheoun;Kim, Jong-Soo;Kwon, Soon-Won
    • Journal of the korean academy of Pediatric Dentistry
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    • v.27 no.4
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    • pp.485-489
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    • 2000
  • A mucocele is a thin-walled, bluish, fluctuant swelling occurring just beneath the oral mucosa and filled with mucoid material. It usually results from damage to a salivary gland following which there is extravasation of mucus into the tissues, or occasionally it forms from dilatation of the duct of a salivary gland. The accepted treatment of a mucocele is excision of the sac and the associated minor salivary gland. Use of the $CO_2$ laser in oral surgery has several advantages. It is a very precise means of cutting tissue and causes little adjacent nontarget tissue damage. There is excellent coagulation of small blood vessels and consequently operative hemorrhage is greatly decreased. There is instant sterilization of the operative site, which decreases bacteremia. The operation sites were completely healed without any infection or complication and discomfort from swelling or pain was not noted in all cases throughout the healing process. In addition, following this therapy, there is little contraction or scarring.

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Pulmonary Pneumatocele in a Pneumonia Patient Infected with Extended-Spectrum β-Lactamase Producing Proteus mirabilis

  • Ryou, Sung Hyeok;Bae, Jong Wook;Baek, Hyun Jin;Lee, Doo Hyuk;Lee, Sang Won;Choi, Gyu Ho;Han, Kyu Hyung;Kim, Se Weon;Kim, Hyunbeom;Hong, Goohyeon
    • Tuberculosis and Respiratory Diseases
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    • v.78 no.4
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    • pp.371-374
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    • 2015
  • Pulmonary pneumatoceles are air-filled thin-walled spaces within the lung and are rare in adult cases of pneumonia. We report the case of a 74-year-old male who was admitted with a cough and sputum production. He had been treated with oral dexamethasone since a brain tumorectomy 6 months prior. Contrast-enhanced computed tomography (CT) of the chest revealed a large pneumatocele in the right middle lobe and peripheral pneumonic consolidation. Bronchoalveolar lavage was performed; cultures identified extended-spectrum ${\beta}$-lactamase (ESBL) producing Proteus mirabilis. A 4-week course of intravenous ertapenem was administered, and the pneumatocele with pneumonia resolved on follow-up chest CT. To the best of our knowledge, this is the first reported case of pulmonary pneumatocele caused by ESBL-producing P. mirabilis associated with pneumonia.

Study on the Clamping Force and the Friction Coefficient in a Bolt tightened up to the Plastic Range (소성역체결 볼트의 체결력과 마찰계수에 관한 연구)

  • 손승요;신근하
    • Computational Structural Engineering
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    • v.7 no.3
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    • pp.133-141
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    • 1994
  • When a bolt is tightened up to the range of plastic deformation, yielding may be governed by the combined stresses due to the axial force developed in the bolt and the frictional torque induced on the thread by the contact with the nut. Consideration is taken account of the fact that the unengaged portion of the thread has least sectional area, being subject to initial yielding. Once yielding has taken place some strain hardening effect may result. Incremental stress-strain relations are used to treat the continued yielding, which is equivalent to treat continued yielding as if summing up the effects of thin walled cylinders subject to plastic deformation. M10 bolts of fine threads are used for both computational and experimental purposes. Variation of axial forces and frictional torques vs. the frictional coefficients are presented together with other plots showing some characterist of bolt under plastic deformation. Finally, a design and control aid for the tightening(i.e., kind of nomograph) is presented, showing the relationships among the torque factor and frictional coefficients for that particular bolt used in the experiment.

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Large deflection behavior and stability of slender bars under self weight

  • Goncalves, Paulo B.;Jurjo, Daniel Leonardo B.R.;Magluta, Carlos;Roitman, Ney;Pamplona, Djenane
    • Structural Engineering and Mechanics
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    • v.24 no.6
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    • pp.709-725
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    • 2006
  • In this paper the buckling and post-buckling behavior of slender bars under self-weight are studied. In order to study the post-buckling behavior of the bar, a geometrically exact formulation for the non-linear analysis of uni-directional structural elements is presented, considering arbitrary load distribution and boundary conditions. From this formulation one obtains a set of first-order coupled nonlinear equations which, together with the boundary conditions at the bar ends, form a two-point boundary value problem. This problem is solved by the simultaneous use of the Runge-Kutta integration scheme and the Newton-Raphson method. By virtue of a continuation algorithm, accurate solutions can be obtained for a variety of stability problems exhibiting either limit point or bifurcational-type buckling. Using this formulation, a detailed parametric analysis is conducted in order to study the buckling and post-buckling behavior of slender bars under self-weight, including the influence of boundary conditions on the stability and large deflection behavior of the bar. In order to evaluate the quality and accuracy of the results, an experimental analysis was conducted considering a clamped-free thin-walled metal bar. As this kind of structure presents a high index of slenderness, its answers could be affected by the introduction of conventional sensors. In this paper, an experimental methodology was developed, allowing the measurement of static or dynamic displacements without making contact with the structure, using digital image processing techniques. The proposed experimental procedure can be used to a wide class of problems involving large deflections and deformations. The experimental buckling and post-buckling behavior compared favorably with the theoretical and numerical results.