• Title/Summary/Keyword: pre-reinforcement

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Study of Startup Policy of Government Research Institute through Importance-Satisfaction Analysis of ETRI Pre-Startup Support Program (ETRI 예비창업지원 프로그램의 ISA 분석을 통한 출연연 기술창업 성과 제고 정책 연구)

  • Gil, Wungyu;Sim, Yongho;Kim, Seokyun
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.11 no.5
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    • pp.45-56
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    • 2016
  • According to attended about startup, there are many policy and program for activating of startup. Government's policy and program was scale up and arrangements for high quality. Nevertheless, policies and programs are concentrated on ante-startup stage. And experts have questioned that effect. So, there are needed a program focusing pre-startup and incubation stage. Accordingly, this study propose a kind of educative program named Pre-Startup Support Program. Through the program, pre-startup teams or entrepreneurs will inspect items, business skills and surroundings of market and competitors. And they have a time for complementation of deficiency. This study selects ETRI spin-off(research based spin-off born ETRI) by means of an object of study. ETRI's programs are started in 2011 with intent to incubate the entrepreneur through market research, mentoring, space of incubation and funds. This study analyze using the ISA(Important-Satisfaction Analyze) and the regression. We classify the pre-startup support program using the ISA. And then, we analyze the influence of satisfaction using the regression. On the basis of results, we identify the effectiveness of pre-startup support program and propose plans for reinforcement. In conclusion, adopting a pre-startup support program is expected to success of startup.

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Flexural strengthening of RCC beams using FRPs and ferrocement - a comparative study

  • Ganesan, N.;Bindurania, P.;Indira, P.V.
    • Advances in concrete construction
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    • v.10 no.1
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    • pp.35-48
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    • 2020
  • This paper deals with a comparative study among three different rehabilitation techniques, namely, (i) carbon fibre reinforced polymer (CFRP), (ii) glass fibre reinforced polymer (GFRP) and (iii) ferrocement on the flexural strengthening of reinforced cement concrete (RCC) beams. As these different techniques have to be compared on a level playing field, tensile coupon tests have been carried out initially for GFRP, CFRP and ferrocement and the number of layers required in each of these composites in terms of the tensile strength. It was found that for the selected constituents of the composites, one layer of CFRP was equivalent to three layers of GFRP and five layers of wiremesh reinforcement in ferrocement. Rehabilitation of RCC beams using these equivalent laminates shows that all the three composites performed in a similar way and are comparable. The parameters selected in this study were (i) the strengthening material and (ii) the level of pre-distress induced to the beams prior to the rehabilitation. It was noticed that, as the levels of pre-distress decreases, the percentage attainment of flexural capacity and flexural stiffness of the rehabilitated beams increases for all the three selected composites used for rehabilitation. Load-deflection behavior, failure modes, energy absorption capacity, displacement ductility and curvature ductility were compared among these composites and at different distress levels for each composite. The results indicate that ferrocement showed a better performance in terms of ductility than other FRPs, and between the FRPs, GFRP exhibited a better ductility than the CFRP counterpart.

Fabrication and Mechanical Properties of TiNi/6061Al Smart Composite by Permanent Mold Casting (금형주조법을 이용한 TiNi/6061Al 지적복합재료의 제조 및 기계적 특성)

  • Kim, Soon-Kook;Lee, Jun-Hee;Yun, Doo-Pyo;Park, Young-Chul;Lee, Gyu-Chang;Kim, Young-Hee
    • Journal of Korea Foundry Society
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    • v.18 no.6
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    • pp.534-540
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    • 1998
  • 6061Al-matrix composite with TiNi shape memory fiber as reinforcement has been fabricated by Permanent Mold Casting to investigate the mechanical properties of the smart composites. The composites have showed good interface bonding as a result of the analysis of SEM and EDX. The smartness of composite is given due to the shape memory effect of the TiNi fiber which generates compressive residual stresses in the matrix material when heated after being prestrained. The tensile strength of the composites was tested at temperatures between $90^{\circ}C$ and room temperature with increasing amount of pre-strain, and it showed that the tensile strength at $90^{\circ}C$ was higher than that of the room temperature. Especially, the tensile strength of the composite increases with increasing pre-strain. It showed that hardness of matrix was higher than that of common 6061Al alloy.

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Effectiveness of seismic repairing stages with CFRPs on the seismic performance of damaged RC frames

  • Duran, Burak;Tunaboyu, Onur;Kaplan, Onur;Avsar, Ozgur
    • Structural Engineering and Mechanics
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    • v.67 no.3
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    • pp.233-244
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    • 2018
  • This study aims at evaluating the performance of repairing technique with CFRPs in recovering cyclic performance of damaged columns in flexure in terms of structural response parameters such as strength, dissipated energy, stiffness degradation. A 2/3 scaled substandard reinforced concrete frame was constructed to represent the substandard RC buildings especially in developing countries. These substandard buildings have several structural deficiencies such as strong beam-weak column phenomenon, improper reinforcement detailing and poor material properties. Flexural plastic hinges occurred at the columns ends after testing the substandard specimen under both constant axial load and reversed cyclic lateral loading. Afterwards, the damaged columns were externally wrapped with CFRP sheets both in transverse and longitudinal directions and then retested under the same loading protocol. In addition, ambient vibration measurements were taken from the undamaged, damaged and the repaired specimens at each structural repair steps to identify the effectiveness of each repairing step by monitoring the change in the natural frequencies of the tested specimen. The ambient vibration test results showed that the applied repairing technique with external CFRP wrapping was proved to recover stiffness of the pre-damaged specimen. Moreover, the lateral load capacity of the pre-damaged substandard RC frame was restored with externally bonded CFRP sheets.

Case Study of a Shallow Tunnelling Through Complex Strata of Sand-Gravel and Rock Mass (모래자갈과 암반의 복합지층에 시공한 저심도 터널의 사례연구)

  • Kim, Cheehwan
    • Tunnel and Underground Space
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    • v.25 no.3
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    • pp.244-254
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    • 2015
  • The tunnel is excavated through the alluvial layer composed of sand and gravel with groundwater deposited on rock. A portion of upper part of the tunnel is located in the alluvial layer and there are several buildings just above the curved section of the tunnel. It is necessary to prevent from sand-flowing into the tunnel due to low strength of the alluvial, high groundwater level and shallow depth of the tunnel from the ground surface. For this, the alluvial around the tunnel is pre-reinforced by umbrella arch method with multi-stage grouting through large diameter steel pipes or jet grouting before excavating the tunnel. The effect of the pre-reinforcement of the tunnel and the safety of the buildings are monitored by measurement of ground deformation occurred during tunnelling.

Flexural Failure Behaviour of RC Beams Strengthened by CFS according to Loading Condition (CFS로 보강된 RC보의 가력상태에 따른 휨파괴 거동)

  • Park, Sung-Soo;Cho, Su-Je
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.7 no.3
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    • pp.223-230
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    • 2003
  • The purpose of this research are to investigate experimentally flexural strengthening effects and flexural behaviour of RC beams strengthened by carbon fiber sheet(CFS) with/without superimposed pre-load. Test parameters of experiment are tension reinforcement ratio(0.85, 1.32, 1.91%) and pre-load(80% of yield capacity of unstrengthened beams). The structural behaviour of strengthened beams are compared with in terms of yield load and ultimate load, load-deflection relation, ductility, strengthened efficiency. From the test results, it were shown that ultimate capacity and flexural failure behaviour of RC beams strengthened by CFS changed by initial stresses between original beams and bonded CFS.

Effect of location of glass fiber pre-impregnated with light-curing resin on the fracture strength and fracture modes of a maxillary complete denture (광중합형 레진에 함침시킨 유리섬유의 위치가 상악 총의치의 파절강도와 파절양상에 미치는 영향)

  • Yoo, Hyun-Sang;Sung, Su-Jin;Jo, Jae-Young;Lee, Do-Chan;Huh, Jung-Bo;Jeong, Chang-Mo
    • The Journal of Korean Academy of Prosthodontics
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    • v.50 no.4
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    • pp.279-284
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    • 2012
  • Purpose: This study evaluated the effect of glass fiber pre-impregnated with light-curing resin on the fracture strength and fracture modes of a maxillary complete denture. Materials and methods: Maxillary acrylic resin complete dentures reinforced with glass fiber pre-impregnated with light-curing resin (SES MESH, INNO Dental Co., Yeoncheongun, Korea) and without reinforcement were tested. The reinforcing material was embedded in the denture base resin and placed different regions (Control, without reinforcement; Group A, center of anterior ridge; Group B, rugae area; Group C, center of palate; Group D, full coverage of denture base). The fracture strength and fracture modes of a maxillary complete denture were tested using Instron test machine (Instron Co., Canton, MA, USA) at a 5.0 mm/min crosshead speed. The flexure load was applied to center of denture with a 20 mm diameter ball attachment. When fracture occurred, the fracture mode was classified based on fracture lines. The data were analyzed with one-way ANOVA at the significance level of 0.05. Results: There were non-significant differences (P>.05) in the fracture strength among test groups. Group A showed anteroposterior fracture and posterior fracture mainly, group B, C and control group showed partial fracture on center area mostly. Most specimen of group D showed posterior fracture. Conclusion: The location and presence of the fiber reinforcement did not affect the fracture strength of maxillary complete denture. However, reinforcing acrylic resin denture with glass fiber has a tendency to suppress the crack.

Equivalent Design Parameter Determination for Effective Numerical Modeling of Pre-reinforced Zones in Tunnel (터널 사전보강 영역의 효과적 수치해석을 위한 등가 물성치 결정 기법)

  • Song, Ki-Il;Cho, Gye-Chun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.8 no.2
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    • pp.151-163
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    • 2006
  • Although various methods for effective modeling of pre-reinforced zones have been suggested for numerical analysis of large section tunnels, tunnel designers refer to empirical cases and literature reviews rather than engineering methods because ones who use commercial programs are unfamiliar with a macro-scale approach in general. Therefore, this paper suggests a simple micro-scale approach combined with the macro-scale approach to determine equivalent design parameters for effective numerical modeling of pre-reinforced zones in tunnel. This new approach is to determine the equivalent stiffness of pre-reinforced zones with combination of ground, bulb, and steel in series or/and parallel. For verification, 3-D numerical results from the suggested approach are compared with those of a realistic model. The comparison suggests that two cases make best approximation to a realistic solution: One is related to the series-parallel stiffness system (hereafter SPSS) in which bulb and steel are coupled in parallel and then connected to the ground in series, and the other is the series stiffness system (hereafter SSS) in which only bulb and steel are coupled in series. The SPSS is recommended for stiffness calculation of pre-reinforced zones because the SSS is inconvenient and time-consuming. The SPSS provides slightly bigger vertical displacement at tunnel crown in weathered rock than other cases and give almost identical results to a realistic model for horizontal displacement at tunnel spring line and ground surface settlement. Displacement trends on weathered rock and weathered soil are similar. The SPSS which is suggested in this paper represents the behavior mechanism of pre-reinforced area effectively.

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Process of Change, Decisional Balance and Self-Efficacy Corresponding to the Stage of Exercise Behavior in Patients with Type 2 Diabetes Mellitus (제 2형 당뇨 환자의 운동행위 변화단계에 따른 변화과정, 의사결정균형 및 자기 효능감에 관한 연구)

  • Kim, Chun-Ja
    • Korean Journal of Adult Nursing
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    • v.14 no.1
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    • pp.83-92
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    • 2002
  • Purpose: This study was performed to identify the process of change, decisional balance and self-efficacy corresponding to the stage of exercise behavior using Transtheoretical Model in patients with type 2 diabetes mellitus. Method: The study method was a survey in 100 type 2 DM patients at out-patients clinic of Y medical center from March 19, 2000 to October 30, 2000. Result: The results were as follows: The subjects were divided into five stages of exercise behavior ; 15.0% in pre-contemplation stage, 33.0% in contemplation stage, 17.0% in preparation stage, 16.0% in action stage and 19.0% in maintenance stage. The subjects in pre-contemplation stage used all processes of change in the least. "Dramatic relief(DR)", "Environmental reevaluation(ER)" and "Self reevaluation(SR)" were identified as main processes of change in contemplation stage. "Consciousness raising(CR)", "DR" were used higher than average in preparation stage. Helping relationships(HR)", "CR", "ER", "SR", "Social liberation(SL)", "Counter conditioning (CC)", "Reinforcement management(RM)", "Self iberation(SEL)" and "Stimulus control(SC)" were used higher than average in action stage. The subjects in maintenance stage used all process of change the highest except "DR"and "HR". "Cons" score of decisional balance was the highest in pre-contemplation stage, "Pros" score was the highest in action stage and "Self-efficacy" score was the highest in maintenance stage. Conclusion: This study can provide the basis of staged matching exercise program using TTM for more effective and useful intervention.

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Buckling and vibration analyses of MGSGT double-bonded micro composite sandwich SSDT plates reinforced by CNTs and BNNTs with isotropic foam & flexible transversely orthotropic cores

  • Mohammadimehr, M.;Nejad, E. Shabani;Mehrabi, M.
    • Structural Engineering and Mechanics
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    • v.65 no.4
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    • pp.491-504
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    • 2018
  • Because of sandwich structures with low weight and high stiffness have much usage in various industries such as civil and aerospace engineering, in this article, buckling and free vibration analyses of coupled micro composite sandwich plates are investigated based on sinusoidal shear deformation (SSDT) and most general strain gradient theories (MGSGT). It is assumed that the sandwich structure rested on an orthotropic elastic foundation and make of four composite face sheets with temperature-dependent material properties that they reinforced by carbon and boron nitride nanotubes and two flexible transversely orthotropic cores. Mathematical formulation is presented using Hamilton's principle and governing equations of motions are derived based on energy approach and applying variation method for simply supported edges under electro-magneto-thermo-mechanical, axial buckling and pre-stresses loadings. In order to predict the effects of various parameters such as material length scale parameter, length to width ratio, length to thickness ratio, thickness of face sheets to core thickness ratio, nanotubes volume fraction, pre-stress load and orthotropic elastic medium on the natural frequencies and critical buckling load of double-bonded micro composite sandwich plates. It is found that orthotropic elastic medium has a special role on the system stability and increasing Winkler and Pasternak constants lead to enhance the natural frequency and critical buckling load of micro plates, while decrease natural frequency and critical buckling load with increasing temperature changes. Also, it is showed that pre-stresses due to help the axial buckling load causes that delay the buckling phenomenon. Moreover, it is concluded that the sandwich structures with orthotropic cores have high stiffness, but because they are not economical, thus it is necessary the sandwich plates reinforce by carbon or boron nitride nanotubes specially, because these nanotubes have important thermal and mechanical properties in comparison of the other reinforcement.