• Laser Solutions
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• v.7 no.2
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• pp.1-10
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• 2004

This work was attempted to join SCP sheet and STS304 sheet by using Nd:YAC laser beam. SCP sheet has good formability and low cost, while STS304 has excellent corrosion resistance and mechanical properties in high temp. In this experiment, butt joint type was used to develop the tailored blank welding for dissimilar steel. Sheets which have different thermal properties. Computer simulation was conducted to obtain the off-set position for efficient welding by considering laser power, scanning speed, focal length and basic properties. The result showed that the optimum thermal distribution was obtained when the laser beam was irradiated at $0.05{\sim}0.1$ mm off-set toward the SCP sheet side. The experiment was conducted based on the result of computer simulation to show the same optimum conditions. Optimum conditions were 3KW in laser beam power, 6m/min in scanning speed, -0.5mm in focal position, 0.1mm off-set toward SCP. Microhardness test, tensile test, bulge test, optical microscopy, EDS, and XRD were performed to observe the microstructure around fusion zone and to evaluate the mechanical properties of optimum conditions, The weld zone had high microhardness values by the formation of the martensitic structure. Tensile test measured the strength of welded region by vertical to strain direction and the elongation of welded region by parallel to strain direction. Bulge test showed $52\%$ formability of the original materials. Bead shape, grain size, and martensitic structure were observed by the optical microscopy in the weld zone. Detailed results of EDS, XRD confirmed that the welded region was connected of martensitic structure.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.6
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• pp.431-438
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• 2016

Recently, concerns about the environment are becoming more important because of global warming and the exhaustion of earth's resources. In the aviation and automobile industries, the application of light materials is increasingly important for eco-friendly and effective. Carbon Fiber Reinforced Plastics is a composite material which great formability and the high strength of carbon fiber. CFRP, which is both light and strong, is hard to manufacture. In addition, CFRP machining has a high chance of defects. This research discusses the development of a manufacturing system package for CFRP machining. It involving CFRP Drilling/Water-jet Manufacturing Machines, Inspection/Post-processing Systems, CNC platform for an EtherCAT servo Communication, Flexible Manufacturing Systems and CFRP machining Processes.

• Journal of Power System Engineering
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• v.16 no.6
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• pp.52-58
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• 2012

Roll forming process is one of the most widely used processes in the world for forming metals such as a furniture drawer guide or an up and down slide guide. It can manufacture goods of the uniform cross section on a large scale throughout the continuous processing. In the domestic design and manufacture, roll forming process for production is taking most of the method of 2-point under rail slide. However, this method is vulnerable to the structural strength and stiffness is not suitable for high load conditions. Therefore, through systematic study of high load, low noise 3-point ball type of under rail slide its own design and manufacturing technology is the need to build. In this paper, to make center member of 3-point ball-type under rail slide for the refrigerator doors, the roll forming modeling and simulation are performed. Tensile test is performed about SCP-1 1/2H for determine the mechanical properties of materials. Modeling and simulation of roll forming is used MSC.MARC software of a dedicated analysis program used by rigid plastic finite element method. Interference between the roll and the final shape are predicted from the results of the simulation.

• Composites Research
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• v.14 no.5
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• pp.1-11
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• 2001

The particulates reinforced metal matrix composites(PMMC) have a number of interesting mechanical properties. including high strength and good resistance to wear at high temperature and low thermal expansion. The equipment structure to obtain the homogeneous distribution in composites are proposed for the continuous pouring of reinforcement at the desired temperature. The particulates reinforced metal matrix composites(A357/SiCp) were fabricated by the process of the combined stirring method with the various fabrication process. The combined stirring method to niform distribution of particle is consisted of two stirring force both electro-magnetic stirring generated from induction heating and mechanical stirring with graphite stirrer. PMMC billets were fabricated with the volume fractions ranged from 0% to 20% and particle sizes ranged from 14${\mu}{\textrm}{m}$ to 25${\mu}{\textrm}{m}$. It is important to cont the size of primary $\alpha$-Al solid particles because it could become the cause of the particle pushing or capture phenomena from the fact that secondary dendrite arm spacing size depends on the cooling rate during the solidification in hypoeutectic Al-Si alloy. Therefore, the effect of primary $\alpha$-Al on the reinforcement distribution in matrix alloys has been investigated. The microstructure of PMMC fabracated with various volume fractions(0%, 10%, and 20%) and particle size were observed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1403-1409
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• 2010

For many years, high-strength nickel-base superalloys have been used to manufacture turbine blades because of their excellent performance at high temperatures. The prediction of fatigue life of superalloys is important for improving the efficiency of the turbine blades. In this study, low cycle fatigue tests are performed for different values of total strain and temperature. The relations between strain energy density and number of cycles before failure occurs are examined in order to predict the low cycle fatigue life of IN738LC super alloy. The results of low cycle fatigue lives predicted by strain energy methods are found to coincide with experimental data and with the results obtained by the Coffin-Manson method.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.22
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• pp.9767-9771
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• 2014

Background: Social support is an important factor in psycho-social well-being of cancer survivors. There is little information about level of social support and its predictors among cancer survivors in Iran or other Middle Eastern countries. The aims of present study were to determine the social support and its prediction factors among Iranian cancer survivors. Materials and Methods: In this descriptive-correlational study 187 cancer patients in one educational center and one private oncology office in northwest of Iran participated using a convenient sampling method. The data collection tool consisted of a researcher-prepared checklist and the Multidimensional Scale of Perceived Social Support Assessment (MSPSS). Data analysis was performed using SPSS statistical software with descriptive statistics and multiple linear regression analysis. Results: The total score of MSPSS was 68 from a possible score between 7 and 84. Participants believed that they received a high level of support from their family members and significant others. Multiple linear regression analysis showed that single and depressed cancer survivors and participants with lower levels of physical activity believed that they received lower levels of social support. Conclusions: Iranian cancer survivors receive high levels of social support and family members are the most important source of this support. In planning any supportive care program for Iranian cancer survivors this strength should be considered. Especially, single and depressed and patients with lower levels of physical activity need more attention.

• Journal of the Korean Wood Science and Technology
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• v.29 no.2
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• pp.118-125
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• 2001

In this study, it was examined the characteristics of bending property of red pine(Pinus densiflora S, et Z.) related to slope of grain. At first, we have investigated the characteristics of wood species for bending property. At second, it was examined the relationships between grain angle and its related bending property. Specimens were made following to grain angle $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, $90^{\circ}$, respectively. Dimension of wood materials was $10mm(T){\times}20mm(R){\times}350mm(L)$. Microwave irradiation time for bending process was 30, 60, 90, 120 seconds. The result of this study were as follows ; 1. Grain angle of wood was closely related to Young's modulus on bending process. In the process of bending with various grain angle, wood bending was easily proceed on the high grain angle range. 2. However, the strength of bent wood was very weak when the grain angle was high. Therefore, it was considered suitable grain angle for bending was existed. 3. The characteristics of wood properties for wood bending were very different among wood species.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.785-788
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• 2008

This study is focused on applying heavyweight concrete to ballast used to have stability of a ship. Generally, heavyweight concrete is made from a high density aggregate like magnetite or limonite. However, these materials are hard to obtain them from relevant companies and so expensive. Therefore, this study plans to product heavyweight ballast concrete which is easy to obtain by recycled iron slag. Heavyweight ballast concrete isn't required to meet some compressive strength in use, but it is required to have high flowable and 2.7t/m3 of bulk density to fill the ballast tank densely. The designed field mix proportion of concrete based on the results of pre-experiment shows it can control the temperature crack and has superior chloride corrosion resistance after conducting chloride corrosion experiment. Also, it is prefer that before airtightness voltile corrosion inhibiter(VCI) is added in airtight space of shipyard.

• Journal of the Korean Ceramic Society
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• v.42 no.8 s.279
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• pp.554-560
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• 2005

The engineering ceramic needs the properties of high strength, hardness, corrosion-resistance and heat-resistance in order to withstand thermal shock or applied nonuniform stresses without failure. The densely coated porous ceramics can be used for machine component, electromagnetic component, bio-system component and energy-system component by their high-performances from superior coating properties and light-weight characteristics due to the structure including pore by itself. In this study we controlled the porosity of silica and alumina, $8.2\~25.4\%$ and $23.4\~36.0\%$, respectively, by the control of sintering temperature and starting powder size. We made bilayer structures, consisting of a transparent glass coating layer bonded to a thick substrate of different porous ceramics by a thin layer of epoxy adhesive, facilitated observations of crack initiation and propagation. The elastic modulus mismatch could be controlled using different porous ceramics as the substrate layer. Then we applied 150 N force using WC sphere with a radius of 3.18 mm by Hertzian indentation. As a result, the crack initiation in the coating layer was delayed at lower porosity in the substrate layer, and the damage in the coating layer was relatively smaller at the bilayer structure coated on higher elastic substrate.

• Journal of the Korean Ceramic Society
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• v.39 no.2
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• pp.153-158
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• 2002

$Al_2O_3$ composites powders with 1∼11 wt% $TiO_2$ were prepared by wet method and sintered at 1350$^{\circ}C$, 1450$^{\circ}C$ for 2h. Mechanical properties and microstructural evolution were investigated in this study. $Al_2O_3$-3 wt% $TiO_2$ composite were high bulk density of 2.37 g/$cm^3$ and low apparent porosity of 6.3%. The composites containing of 3 wt% $TiO_2$ showed moderately high bending strength of 68.9 MPa and the young's modulus of 35.5 MPa. The composites with increasing $TiO_2$ contents exhibit reduced thermal expansion coefficient due to the formation of $Al_2TiO_5$ phase.