• Title/Summary/Keyword: MTS machine

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Strength and Crack-Damage Control Characteristics of Concrete Beams Layered with Strain-Hardening Cement Composites (SHCCs) (변형 경화형 시멘트 복합체로 단면 대체된 콘크리트 보의 강도 및 균열손상 제어 특성)

  • Yun, Hyun-Do;Kim, Sun-Woo;Jeon, Esther;Kim, Yun-Soo;Jang, Kwang-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.269-272
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    • 2008
  • This paper reports on the cracking mitigation and flexural behavior experimentally observed in concrete prisms layered with strain-hardening cement composites (SHCCs) which is micro-mechanically designed cement composite and exhibits pseudo tensile strain-hardening behavior accompanied by multiple cracking while using a moderate amount of fiber, typically less than 2 percent in term of fiber volume fraction. In this study, SHCC is reinforced with 1.3 percent polyvinyl alcohol (PVA) and 0.20 percent polyethylene (PE) in volume fraction. Tests were conducted using $100{\times}100{\times}400mm$ long prisms supported over a simply supported span of 350mm. The four point load was applied using MTS servo control machine. The thickness patched with SHCC is the main variable for this study. Experimental study shows that when subject to monotonic flexural loading, the SHCC layered repair system showed 2.7 - 4.2 times increased load carrying capacity, and mitigated cracking damage of concrete beams layered with SHCC compared with plain concrete beams.

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Role of Post Weld Treatment Methods in the Improvement of Fatigue Life for T-type Welded Structures Made by SM 50A Steel (SM 50A 강으로 제작된 T-형 용접형상의 용접후처리 방법이 피로수명 증가에 작용하는 역할)

  • Han, Chang-Wan;Lee, Jae-Hoon;Song, Jun-Hyouk;Lee, Hyun-Woo;Park, Seong-Hun
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.3
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    • pp.307-312
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    • 2012
  • This study aims to investigate the effect of the post weld treatments on the fatigue life of T-type welded structure made by a SM50A steel material, generally used for excavators, because changes in the geometry, material and surface properties of welded regions affect the fatigue life of welded structures. T-type test specimens were prepared by the CO2 welding of rolled steel plates (SM50A steel) with a thickness of 10 mm at a welding speed of 30 cm/min and these Ttype welded specimens were further treated by UIT (Ultrasonic Impact Treatment) and/or toegrinding post welding treatment methods. In order to investigate improvements on the fatigue life of the samples. 3-point bending fatigue tests were conducted with a stress ratio of R=0.1 under a cyclic loading environment at a frequency of 5 Hz, via a hydraulic fatigue testing machine (${\pm}100\;kN$, MTS 809). The tests were performed at room temperature. The fatigue life of UIT specimens was approximately 25 times longer than that of as-welded specimens at a stress amplitude of 281 MPa, while toe-grinding specimens exhibited 4.15 times longer fatigue life. The current results could provide important guidelines to determine the proper post weld treatment methodologies of T-type welded parts for excavators with a satisfactory fatigue life although under severe operating conditions.

Material Characteristics of Dental Implant System with In-Vitro Mastication Loading

  • Jeong, Tae-Gon;Jeong, Yong-Hun;Lee, Su-Won;Yang, Jae-Ung;Jeong, Jae-Yeong;Park, Gwang-Min;Gang, Gwan-Su
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2018.06a
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    • pp.72-72
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    • 2018
  • A dynamic fatigue characteristic of dental implant system has been evaluated with applying single axial compressive shear loading based on the ISO 14801 standard. For the advanced dynamic fatigue test, multi-directional force and motion needed to be accompanied for more information of mechanical properties as based on mastication in oral environment. In this study, we have prepared loading and motion protocol for the multi-directional fatigue test of dental implant system with single (Apical/Occlusal; AO), and additional mastication motion (Lingual/Facial; LF, Mesial/Distal; MD). As following the prepared protocol (with modification of ISO 14801), fatigue test was conducted to verify the worst case results for the development of highly stabilized dental implant system. Mechanical testing was performed using an universal testing machine (MTS Bionix 858, MN, USA) for static compression and single directional loading fatigue, while the multi-directional loading was performed with joint simulator (ADL-Force 5, MA, USA) under load control. Basically, all mechanical test was performed according to the ISO 14801:2016 standard. Static compression test was performed to identify the maximum fracture force with loading speed of 1.0 mm/min. A dynamic fatigue test was performed with 40 % value of maximum fracture force and 5 Hz loading frequency. A single directional fatigue test was performed with only apical/occlusal (AO) force application, while multi directional fatigue tests were applied $2^{\circ}$ of facial/lingual (FL) or mesial/distal (MD) movement. Fatigue failure cycles were entirely different between applying single-directional loading and multi-directional loading. As a comparison of these loading factor, the failure cycle was around 5 times lower than single-directional loading while applied multi-directional loading. Also, the displacement change with accumulated multi-directional fatigue cycles was higher than that of single directional cycles.

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Study on the Thermal and Dynamic Behaviors of Air Spring for vibration isolation of LCD panel inspecting machine connected with an External Chamber through a flexible tube: PART II, Experimental validation and investigation (외부챔버와 유연한 튜브로 연결된 LCD 패널 검사기 방진용 공기 스프링의 열 및 동적 연성거동에 대한 연구: PART II, 실험적 검증 및 고찰)

  • Seok, Jong-Won;Lee, Ju-Hong;Kim, Pil-Kee
    • Journal of the Semiconductor & Display Technology
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    • v.10 no.1
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    • pp.43-49
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    • 2011
  • In this study, the dynamic characteristics of an air spring connected with an external chamber through a flexible tube are examined. The uncoupled dynamic parameters of the air spring are identified through experiments, followed by the suggestion of a model-based approach to obtain the remaining coupled dynamic parameters using the various frequency response functions derived in PART I paper [1]. To improve or control the damping characteristics of the air spring, this vibration isolation air spring system is physically established in laboratory scale. And we attempt to identify various parameters used to describe to air spring system by both theoretically [1] and experimentally, which is performed in this report. The damping parameter of the tube system is identified through experiments on the system incorporated with the air cylinder, and a nonlinear regression procedure is employed to find solutions. The resulting value is used to expect the frequency response function of dynamic pressure in the top chamber (air spring) with respect to that in the bottom chamber (external chamber). Comparison with the experimental data supports the validity of the present estimation procedures. Also, the dynamic mechanism of the damping effects particularly in a low frequency range is investigated through this experimental endeavor.

A STUDY ON THE BOND STRENGTH OF RESIN-RETAINED PROTHESIS WITH VARIOUS CAST RETAINER DESIGNS (주조체의 설계 변화에 따른 수지접착형 보철물의 접착강도에 관한 연구)

  • Joo Dae-Won;Chang Ik-Tae;Kim Kwang-Nam
    • The Journal of Korean Academy of Prosthodontics
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    • v.30 no.4
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    • pp.508-525
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    • 1992
  • The purpose of this study was to evaluate the effect of some resistance form designs on the bond strength of resin-retained prosthesis. Six sub-groups are designed in natural teeth group and resin teeth group . The framework designs in natural teeth group: 1) no groove preparation 2) groove at the center of distal surface 3) groove at the distobuccal line angle 4) 45 degree lateral load with no groove 5) 45 degree lateral load with center groove 6) splint two teeth with no groove. The framework designs in resin teeth group: 1) no groove preparation 2) groove at the center of distal surface 3) groove at the distobuccal line angle 4) metal covered the 1/2 of distal surface 5) metal covered the 1/2 of mesial surface 6) metal extended over the 114 of buccal surface. Specimens were treated electrolytic etching by Oxy-Etch and cemented with Panavia EX. Failure load was measured by Instron. Another 30 specimens were carried out fatigue tests by MTS 810 fatigue testing machine for 5000 cycles at different load level. The following results were obtained from this study. 1. The failure load was significantly increased by resistance forms. 2. The failure load was not increased by increase of total surface area bonded with teeth. The distal surface area played an important role in failure load. 3. In 45 degree lateral load group, the failure load was decreased significantly than that of in vertical load group. 4. Bond failure modes between static test and fatigue test exhibited no differences.

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Study of the Plating Methods in the Experimental Model of Mandibular Subcondyle Fracture (하악골 과두하부 골절 실험모델에서 견고정을 위한 플레이트 고정방법 연구)

  • Lee, Won;Kang, Dong Hee
    • Archives of Craniofacial Surgery
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    • v.12 no.1
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    • pp.12-16
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    • 2011
  • Purpose: This study examined the biomechanical stability of four different plating techniques in the experimental model of mandibular subcondyle fracture. Methods: Twenty standardized bovine tibia bone samples ($7{\times}1.5{\times}1.0cm$) were used for this study. Each of the four sets of tibia bone was cut to mimic a perpendicular subcondyle fracture in the center area. The osteotomized tibia bone was fixed using one of four different fixation groups (A,B,C,D). The fixation systems included single 2.0 mm 4 hole mini adaption plate (A), single 2.0 mm 4 hole dynamic compression miniplate (B), double fixation with 2.0 mm 4 hole mini adaption plate (C), double fixation with a 2.0 mm 4 hole mini adaption plate and 2.0 mm 4 hole dynamic compression miniplate (D). A bending force was applied to the experimental model using a pressure machine (858 table top system, $MTS^{(R)}$) until failure occurred. The load for permanent deformation, maximum load of failure were measured in the load displacement curve with the chart recorder. Results: Double fixation with a 2.0 mm 4 hole mini adaption plate and a 2.0 mm 4 hole dynamic compression miniplate (D) applied to the anterior and posterior regions of the subcondyle experimental model showed the highest load to failure. Conclusion: From this study, double fixation with an adaption plate and dynamic compression miniplate fixation technique produced the greatest biomechanical stability. This technique may be considered a useful means of fixation to reduce the postoperative internal maxillary fixation period and achieve early mobility of the jaw.

A Study on the Modeling for Boom Structural Behaviors of the Triaxial Woven Fabric Composite (3-방향 직물 복합재료 모델링 및 붐 구조물의 거동 연구)

  • Seon-Woo, Byun;Ji-Yoon, Yang;Soo-Yong, Lee;Jin-Ho, Roh
    • Journal of Aerospace System Engineering
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    • v.16 no.6
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    • pp.99-105
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    • 2022
  • This paper studied the mechanical characteristics of boom structures by verifying the modeling method of representing unit cells of triaxial woven fabric (TWF) composites. The modeling of the representative unit cell obtained the ABD matrix by analysing the behaviour of tensile, shear, bending, and torsion using the periodic boundary conditions for the beam element. This study aimed to validate the ABD matrix by comparing the tensile analysis output from a finite element program with the experimental results from an MTS 810 machine. Additionally, the mechanical characteristics of a TWF composite boom structure were determined through bending analysis and experiments. The findings of this research are expected to be beneficial for developing structures using TWF composites.

Instantaneous Compliance and Creep Compliance functions of Early-Age Concrete under Quasi-Instantaneous Loading (준-순간 하중에 의한 초기재령 콘크리트의 순간 및 크리프 컴플라이언스 함수)

  • Oh Byung-Hwan;Choi Seong-Cheol;Park Ho
    • Journal of the Korea Concrete Institute
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    • v.17 no.1 s.85
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    • pp.11-18
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    • 2005
  • In order to accurately assess the stresses occurring in the early-age concrete, a compliance function which can consider the characteristics of early-age concrete is required. Existing compliance functions, however, have the limit that they have been deduced from the data of hardened concrete and therefore, do not take into account the fast development of material properties in early-age concrete. Furthermore, the distinction between instantaneous compliance and creep compliance is not clear in the existing experimental method. The purpose of present study is to propose a compliance function which can describe the rapid change of hardening processes in early-age concrete. To this end, a test method which can estimate the instantaneous compliance without creep effects in the early-age concrete was suggested first. Based on the suggested experimental method, tests on the instantaneous as well as creep compliance were performed using MTS automatic servo-loop test machine. The test results showed that both instantaneous and aging viscoelastic compliance, which are constants in B3 model, were functions in terms of age of concrete especially at early ages. Therefore, the modified compliance function based on B3 model was proposed to provide more realistic prediction on the behavior of early-age concrete. It is expected that the present model allows more realistic evaluation of varying stresses in concrete structures at early ages.

Effect of Slow-release Fertilizer Levels of Rice in Different Cultural Methods (벼 재배양식에 따른 유효성 비료의 시용량이 생육과 수량에 미치는 영향)

  • 정진일;최원영;최민규;이선용
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.40 no.6
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    • pp.747-756
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    • 1995
  • To find out the optimum application method of slow-releasing fertilizer(SRF) and conventional fertilizer(CF) with different fertilization rate under two culture methods[l0-day old seedling machine transplanting(MT) and direct-sowing on dry paddy(DS)] in the south-western region(clay loam soil) of Korea, used were Chosun slow-releasing fertilizer(silicate latex coated fertilizer: N-P$_2$O$_{5}$-K$_2$O =18-12-13) and conventional fertilizer. Plant height and number of tillers with different two culture methods were higher at MT than DS in early growth. The ratio of dry weight in heading stage was higher at CF than SRF in MT than DS and especially, SRF 80% + CF 20% than SRF 100% or CF 100%. Leaf area index (LAI) in heading stage was higher at CF in MT but higher at SRF in DS than their counterparts. Chlorophyll content was higher at SRF than in CF expect for heading stage(HS), especially in DS. It was highest at HS in CF without its difference during maximum tillering stage(MTS) and panicle formation stage(PFS), while highest at PFS in SRF with tendency of gradual increase and decrease before and after PFS, respectively. Heading was delayed 2~3 days at SRF in two cultrue methods and 4~5 days at SRF in DS in comparison with CF in MT with delay of 2 days at DS compared with MT. Culm length was longer at CF in MT and at SRF in DS than their counterparts. Panicle number per m was more at SRF and in DS. Filled grain ratio was higher at CF and in MT. Yield was obtained 101 and 100% at 100% and 80% level of SRF in DS respectively, and 96% at 80% level of CF in MT, compared with conventional application method (516kg /l0a), and increased 2~4% at DS and 0~3% at MT in SRF. Yield was high in order of 100%(SRF) =80%(SRF) + 20%(CF) > 100%(SRF) + 20%(CF) > 80%(SRF) at MT and 80%(SRF) + 20%(CF) =100%(SRF) > 80%(SRF) =100%(SRF) + 20%(CF) at DS.

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