• 한국안전학회지
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• 제17권4호
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• pp.146-152
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• 2002

The steel shows plastic deformation after the yield point exceeds. Because of overloads, the plastic deformation occurs at the interior support of a continuous bridge. The plastic deformation is concentrated at the interior support, and the permanence deformation at the interior support remains after loads pass. Because local yielding causes the positive moment at the interior support, it is called "auto moment". Auto moment redistributes the elastic moment. Because of redistribution, auto moment decreases the negative moment at the interior support of a continuous bridge. In this paper, the moment-rotation curve from Schalling is used. The Plastic rotation is computed by using Beam-line method, and auto moment is calculated based on the experiment curve. The design example is presented using limit state criterion.

• 한국지반공학회지:지반
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• 제13권2호
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• pp.155-168
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• 1997

격자지보는 NATM에서 터널굴착 후 곧바로 설치되는 강지보재의 한 종류로서 기존의 H형강 지보재를 대체하고자 유럽에서 개발된 새로운 종류의 지보재이다. 격자지보는 강봉을 삼각형태로 엮어 만들었기 때문에 숏크리트 타설이 용이하고 지보재 배면에 생기는 공동을 최소화 할 수 있는 장점이 있다. 또한 격자지보와 숏크리트 복합구조체는 결합력이 우수하여 일체화된 구조체로서 거동하기 때문에 지압을 효과적으로 지지할 수 있다. 본 연구에서는 격자지보와 숏크리트 복합구조체의 특성파악을 위해 실시한 모형벽체 시험, 모형벽체에 타설된 숏크리트의 강도특성시험, 격자지보와 숏크리트의 부착강도시험 결과를 제시하였다. 실험결과 숏크리트가 타설된 격자지보는 숏크리트가 타설된 H형강 지보재에 비해 숏크리 트 리바운드, 타설된 숏크리트의 강도, 부착특성 등이 우수한 것으로 판명되었고, 이로써 격자지로는 적절한 터널지보재로서의 역할을 할 것으로 판단되었다.

• Composite Materials and Engineering
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• 제3권3호
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• pp.201-220
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• 2021

In this study, potential of three machine learning techniques i.e., M5P, Support vector machines and Gaussian processes were evaluated to find the best algorithm for the prediction of flexural strength of concrete mix with steel fibre. The study comprises the comparison of results obtained from above-said techniques for given dataset. The dataset consists of 124 observations from past research studies and this dataset is randomly divided into two subsets namely training and testing datasets with (70-30)% proportion by weight. Cement, fine aggregates, coarse aggregates, water, super plasticizer/ high-range water reducer, steel fibre, fibre length and curing days were taken as input parameters whereas flexural strength of the concrete mix was taken as the output parameter. Performance of the techniques was checked by statistic evaluation parameters. Results show that the Gaussian process technique works better than other techniques with its minimum error bandwidth. Statistical analysis shows that the Gaussian process predicts better results with higher coefficient of correlation value (0.9138) and minimum mean absolute error (1.2954) and Root mean square error value (1.9672). Sensitivity analysis proves that steel fibre is the significant parameter among other parameters to predict the flexural strength of concrete mix. According to the shape of the fibre, the mixed type performs better for this data than the hooked shape of the steel fibre, which has a higher CC of 0.9649, which shows that the shape of fibers do effect the flexural strength of the concrete. However, the intricacy of the mixed fibres needs further investigations. For future mixes, the most favorable range for the increase in flexural strength of concrete mix found to be (1-3)%.

• 한국자동차공학회논문집
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• 제16권6호
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• pp.39-47
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• 2008

In this research, a web-based design support system is constructed for the design process of automotive steel pulley to gather engineering knowledge from pulley design data. In the design search module, a clustering tool for design data is proposed using K-means clustering algorithm. To obtain correlational patterns between design and FEA (Finite Element Analysis) data, a Multi-layer Back Propagation Network (MBPN) is applied. With the analyzed patterns from a number of simulation data, an estimation of minimum von mises can be provided for given design parameters of pulleys. The case study revealed fast estimation of minimum stress in the pulley within 12% error.

• 대한산업공학회지
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• 제3권2호
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• pp.29-40
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• 1977

Some of the steel works and machine tool manufacturers representing the whole spectrum of these industries in Korea are surveyed with a viewpoint from total quality control. The operation of quality control system in these fields has been found to be unsatisfactory partly because these industries are relatively young compared with those in advanced foreign countries, and partly because there have been insufficient financial and top management support. Some suggestions are made for the improvement of steel and machine tools quality. One of them is introducing the industrial engineering techniques, with additional quality control costs and full management support, into the company-wide quality control system.

• 한국안전학회지
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• 제21권4호
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• pp.49-54
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• 2006

The evaluation of elastic-plastic fracture characteristic was investigated in ferrite steel SA 516- Gr70 used for reactor coolant piping elbow and support skirt of pressure vessels. This paper describes the effect of temperature on J-R curve characteristic of this material. The elastic-plastic fracture mechanics parameter J is obtained with unloading compliance method. The test method were analyzed according to ASTM E 813-89 and E 1152-89. Unloading compliance $J_{IC}$ tests were performed on 1 CT specimens at varied temperatures from $25^{\circ}C$ to about $400^{\circ}C$ using a high temperature extensometer. At all temperature, valid $J_{IC}$ measurements could be made and $J_{IC}$ decreased with increasing temperature. SEM fractography schematically illustrates microvoid initiation, growth and coalescence at the tip of a preexisting crack.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.745-750
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• 2000

The rigidity of pier is important in the analysis of rail on high speed railway bridges. This study is being performed because of followings. 1) Actual longitudinal stiffness of the structure including substructure should be considered in the calculation of longitudinal stresses in rails. 2) There are many uncertainties in piers and foundations for design. 3) Actual guideline for the design of piers is necessary. 4) Measurement on the rigidity of pier according to the types of pier, foundation and soil-condition is needed. Curve for rigidity will be obtained through this study and applied for actual design as the guideline. Stresses in rails can be estimates accurately. A pair of piers, which consists of pot-bearing for fixed support and pad-bearing for movable support, is loaded by steel frame through steel wire ropes. The responses which are intended to measure in the field test are displacements, forces and tilts on the top of piers.

• 한국압력기기공학회 논문집
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• 제8권2호
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• pp.33-41
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• 2012

The component cooling water heat exchangers are critical components in a nuclear power plant. As the operation years of the heat exchanger go by, the maintenance costs required for continuous operation also increase. Most heat exchangers have carbon steel shells, tube support plates and flow baffles. The titanium tube is susceptible to flow induced vibration. The damage on carbon steel tube support rod and titanium tube around cooling water entrance area is inevitable. Therefore, analysis of internal flow around the component cooling water entrance and tube channel is a good opportunity to seek for failure prevention practice and maintenance method. The numerical study was carried out by FLUENT code to find out the causes of tube failure and its location.

• 한국막학회:학술대회논문집
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• 한국막학회 2003년도 The 4th Korea-Italy Workshop
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• pp.25-28
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• 2003

Low cost composite metallic membranes for the hydrogen separation and production have been prepared by using thin Pd-Ag foils reinforced by metallic (stainless steel and nickel) structures. Especially, “supported membranes” have been obtained by a diffusion welding procedure in which Pd-Ag thin foils have been joined with perforated metals (nickel) and expanded metals (stainless steel): in these membranes the thin palladium foil assures both the high hydrogen permeability and the perm-selectivity while the metallic support provides the mechanical strength. A second studied method of producing "laminated membranes" consists of coating non-noble metal sheets with very thin palladium layers by diffusion welding and cold-rolling. Palladium thin coatings over these metals reduce the activation energy of the hydrogen adsorption process and make them permeable to the hydrogen. In this case, the dense non-noble metal has been used as a support structure of the thin Pd-Ag layers coated over its surfaces: a proper thickness of the metal assures the mechanical strength, the absence of defects (cracks, micro-holes) and the complete hydrogen selectivity of the membrane. membrane.

• 소음진동
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• 제9권2호
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• pp.273-284
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• 1999

The cylindrical shells are used as primary components of complex structures such as airplane fuselages and nuclear pressure vessels. Recently the free vibration analysis of these structures are investigated by many researchers. The engineering informations on experimental validation of the free vibration behavior on the simply supported cylindrical shells are very few. The experimental methods for realizing the physical boundary condition of simply supported edges are examined. Natural frequencies and mode shapes of the isotropic and plain weave composite simply supported shells are obtained by modal tests. A theoretical and finite element analysis are also performed in order to validate the experimental results. The experimental results indicate that the simply supported boundary conditions with bolts along the circumferential direction of shell in both ends are well achieved. Those are shown to agree with the analytical results and with the finite element analysis results. These methods can be used to realize other experimental simple support boundary conditions.