• Journal of the Korean Society of Safety
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• v.12 no.2
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• pp.17-21
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• 1997

The fatigue crack propagation rate has so far been measured by the effective stress intensity factor range Δ K/sub eff/. But no research has been done to study how much the crack opening ratio influences the expectation of the fatigue crack propagation. Therefore, this paper evaluates of the crack opening ratio on the fatigue crack propagation life by using the method of parameter sensitivity study. Summarizing the result ; ( 1 ) When the crack opening ratio U' is high, the effect of U' gets larger than any other except for the material factor m. But when U' is low, the effect is also diminished. Therefore, the selection of the lowest value possible is desirable in the evaluation of life. (2) When the value of the material factor m is high, the effect of crack opening ratio U' is increased, at the same time the effect of the other parameters also increased wholly. The effect of material factor m itself on life is high, but in case the material factor m is high, that the effect of each parameter on life get higher is unique. In designing, better attention to the material selection should be drawn. (3) In case the stress ratio R gets smaller, the effect of crack opening ratio U' is unchangeable. But the effect of R itself remarkably decreases, and the effect of material factor m somewhat decreases.

• Korean Institute of Interior Design Journal
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• v.15 no.6 s.59
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• pp.60-67
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• 2006

In modem days when architectural materials have grave impacts on overall design expression, materials for architecture, especially finishing materials have become the most essential elements for the design expression, as architectural space and form have been. When it comes to the architectural materials, they can be conceived by visual and tactile sensory system and perceptional system which based on memory and experience. This study confirms how materials bring into effect on architecture in the sense of its design. The main subject of this analysis is expression method of architectural finishing materials. Also, this study finds out the relationship between finishing materials and the images of materials by analyzing the effect factor of architectural material expression with the perspectives of materials, formal and environments and by examining roles of the architectural materials in design. The material factor, in the expression of materiality, is how to make tectonic space and to vary the surface of building as finishing material design. The formal factor is related to set up the new direction in the architectural form and to create the dynamic and informal space. And the social and cultural environment as the effect factor gives new situation and context to architectural material expression. This principle enables us to use architectural materials as one of the important elements which express the whole characteristics of the area.

• Journal of Ocean Engineering and Technology
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• v.25 no.1
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• pp.67-72
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• 2011

Offshore structures, such as a platform, a buoy, or a floating vessel, are exposed to several dynamic loads, and viscoelastic damping material is used to reduce the vibration of offshore structures. It is important to know the properties of viscoelastic materials because loss factor and Young's modulus of the viscoelastic damping material are dependent on frequency and temperature. In this study, an advanced technique for obtaining accurate loss factor and Young's modulus of the viscoelastic damping material is introduced based on a multi degree of freedom curve-fitting method and the RKU (Ross-Kerwin-Ungar) equations. The technique is based on a modified experimental procedure from ASTM E 756-04. Loss factor and Young's modulus of the viscoelastic damping material are measured for different temperatures by performing the test in a temperature-controlled vibration measurement room where temperature varies from 5 to 45 degrees Celsius.

• Journal of the Korea Fashion and Costume Design Association
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• v.12 no.1
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• pp.51-59
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• 2010

The purpose of this study is to help understanding of Korean fashion image by studying of design factor and formative characteristic. The methods of this study are the study of academic literatures as well as practical study through the analysis of case studies about actual works. The summary of this study's results is like followings. First, Perspectives seeing formative characteristic on Korean fashion image are Shape with a line, color, material, pattern, accessories. Second, Design factors deciding Korean fashion image are pattern, then in order of shape, color, material, accessories. Third, In results on design factor deciding Korean fashion image, when fashion designers focus on pattern, pattern is focused on without regard for other design factor. But color and material are accompanied by other design factor in expressing Korean fashion image. As fashion design point expressing Korean astetic, use of pattern is minimized other design factor, color and material are used with other design factor, then Korean fashion image will come out more than other time else. If We develop Korean fashion design to concentrate on shape and pattern, Korean fashion culture will be known to world people and beautiful value of Korean fashion will be handed effectively.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.10a
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• pp.194-197
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• 1996

The high-strength aluminum alloy 7075-T651 was used to observe the fatigue-crack-propagation behavior for the various stress ratios with constant amplitude loading and thus to predict the fatigue life. With a chevron notch in the specimen the fatigue-crack-propagation behavior of through crack was investigated. Crack propagation behavior of through crack in the depth direction and crack growth of weldments were experimentally studied. Base material heat affected zone and weld material were considered in the fracture of weldments. The change of crack-propagation length with respect to several parameters such as stress intensity factor range(ΔK) effective stress intensity factor range(ΔKeff)ration of effective stress intensity factor range(U) stress intensity factor of crack opening point(K op) maximum stress intensity factor(K max) and number of cycles(Nf)was determined. The crack length of through crack of weldments was 2.4mm and the remaining part was a base material. The experiment was accomplished by making the crack propagate near the base material.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.846-851
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• 2017

Piezoelectricity is the capability of a piezoelectric material to change mechanical energy into electrical energy. The determination of electrical and mechanical properties plays a significant role in characterizing the piezoelectric material. The energy losses characteristics of piezoelectric material can be described by mechanical quality factor. In this paper, the output voltage and mechanical quality factor of Lead Zirconate Titanate (PZT-4A) piezoelectric material is determined under various resistance and loading conditions by using the test setup. The commercial FEM software ABAQUS is used to analyze the performance of piezoelectric material under static loading conditions. It is observed that these properties affect the performance of a material particularly in the designing of smart structures. The experimental results are partially compared to the simulation values.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.3
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• pp.235-241
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• 2016

Underwater weapon system is required to structurally strong material, since as it is directly exposed to external shock. It should also be using the lightweight material in order to take advantage of buoyancy. Composite materials meet these requirements simultaneously. Particularly in the case of submarine, composite materials are widely used. It is important to have a high strength enough to be able to withstand external shock, but it is also important to attenuate it. In a method for the shock damping, viscoelastic damping materials are inserted between the high strength composite material as a sandwich structure. Shock attenuation can be evaluated in the loss factor. In ASTM(American Society of Testing Materials), evaluation method of the loss factor of cantilever specimens is specified. In this paper, mode tests of the cantilever are performed by the ASTM standard, in order to calculate the loss factor of the viscoelastic damping material by the specified expression. Further, for verifying of the calculated loss factor, mode test of compound beams is carried out. In addition, the characteristics of the material were analyzed the effect on the loss factor.

• Journal of the Korea Concrete Institute
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• v.12 no.2
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• pp.21-30
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• 2000

In the Ultimate Strength Design, the design strength of a member is determined by multiplying the strength reduction factor to the nominal strength. This concept may be a reasonable approach, however it can not consider failure modes appropriately. Moreover, column design strength diagram show an abrupt change at a low level of axial load, which does not seem to be reasonable. This research compares the design strength determined by the strength resistance factors. As the material resistance factors for flexure and compression, 0.65 and 0.90 are proposed for concrete and steel, respectively. The design strength calculation process by applying material resistance factors addresses failure modes more effectively than by applying member strength reduction factor, and provides more resnable design strength for reinforced concrete flexural and compression members.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.6
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• pp.1382-1387
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• 1994

A model is constructed to evaluate the stress intensity factors for a center crack subjected to anti-symmetric loading in a layered material. A Fredholm integral equation is derived using the Fourier integral transform method. The integral equation is numerically analyzed to evaluate the effects of stress intensity factor on the shear modulus, Poisson's ratio and crack length to layer thickness. In case of the isotropic homogeneous material, the values of stress intensity factor derived in the present study agree with the previous solutions.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2007.04a
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• pp.37-47
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• 2007

Factor : Structure Metal pad & SMO size Board level TC test : - Large SMO size better Board level Drop test : - Large SMO size better Factor : Structure Substrate thickness Board level TC test : - Thick substrate better Board level Drop test : - Substrate thickness is not a significant factor for drop test Factor : Material Solder alloy Board level TC test : - Not so big differences over Pb-free solder and NiAu, OSP finish Board level Drop test : - Ni/Au+SAC105, CuOSP+LF35 are better Factor : Material Pad finish Board level TC test : - NiAu/NiAu is best Board livel Drop test : - CuOSP is best Factor : Material Underfill Board level TC test - Several underfills (reworkable) are passed TCG x500 cycles Board level Drop test : - Underfill lots have better performance than non-underfill lots Factor : Process Multiple reflow Board level TC test : - Multiple reflow is not a significant actor for TC test Board level Drop test : N/A Factor : Process Peak temp Board level TC test : - Higher peak temperature is worse than STD Board level Drop test : N/A Factor : Process Stack method Board level TC test : - No big difference between pre-stack and SMT stack Board level Drop test : - Flux dipping is better than paste dipping but failure rate is more faster