• Structural Engineering and Mechanics
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• v.69 no.2
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• pp.231-241
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• 2019

In this paper, a new higher order shear deformation model is developed for static and free vibration analysis of functionally graded beams with considering porosities that may possibly occur inside the functionally graded materials (FGMs) during their fabrication. Different patterns of porosity distributions (including even and uneven distribution patterns, and the logarithmic-uneven pattern) are considered. In addition, the effect of different micromechanical models on the bending and free vibration response of these beams is studied. Various micromechanical models are used to evaluate the mechanical characteristics of the FG beams whose properties vary continuously across the thickness according to a simple power law. Based on the present higher-order shear deformation model, the equations of motion are derived from Hamilton's principle. Navier type solution method was used to obtain displacement, stresses and frequencies, and the numerical results are compared with those available in the literature. A comprehensive parametric study is carried out to assess the effects of volume fraction index, porosity fraction index, micromechanical models, mode numbers, and geometry on the bending and natural frequencies of imperfect FG beams.

• Journal of the Korean Society of Clothing and Textiles
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• v.48 no.5
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• pp.855-865
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• 2024

Product images in online fashion retail play a crucial role in shaping consumers' decision-making processes. This study investigates the effects of product display types (i.e., flat vs. human display) on consumers' purchase intentions and willingness to pay (WTP) in online fashion retailing. Using a basic shirt as the target product, we examine how overall certainty of fit (OCF) is perceived differently based on the product display type, and for which individuals the effect is amplified, considering individual differences in the need for touch (NFT). A one-factor (flat vs. human display type) between-subject experiment was conducted via an online survey platform (N = 212). The results indicated that the flat display mode generates a higher purchase intention than the human display, along with a marginally higher WTP. Additionally, the positive effect of a flat display on OCF was significant for individuals with low NFT. This study extends our understanding of online retail product displays and their influence on consumer behavior, yielding valuable insights for marketers to improve product presentation in online retail environments.

• Steel and Composite Structures
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• v.15 no.1
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• pp.41-55
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• 2013

This paper presents a numerical study of axially loaded concrete-filled steel tubular columns with "T" shaped cross section (CFTTS) based on the ABAQUS standard solver. Two types of columns with "T" shaped cross section, the common concrete-filled steel tubular columns with "T" shaped cross section (CCFTTS) and the double concrete-filled steel tubular columns with "T" shaped cross section (DCFTTS), are discussed. The failure modes, confining effects and load-displacement curves are analyzed. The numerical results indicate that both have the similar failure mode that the steel tubes are only outward buckling on all columns' faces. It is found that DCFTTS columns have higher axial capacities than CCFTTS ones duo to the steel tube of DCFTTS columns can plays more significant confining effect on concrete. A parametric study, including influence of tube thickness, concrete strength and friction coefficient of tube-concrete interface on the axial capacities is also carried out. Simplified formulae were also proposed based on this study.

• International Journal of Fluid Machinery and Systems
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• v.2 no.3
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• pp.260-268
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• 2009

The effects of acoustic modes in the penstock on the self-excited oscillation in hydraulic power system were studied by assuming a finite sound velocity in the penstock. The flow in the draft tube is considered to be incompressible assuming that the length of the draft tube is smaller than the wavelength of the oscillation. It was found that various acoustic modes in the penstock can become unstable (amplified) by the diffuser effect of the draft tube or the effect of swirl flow from the runner. Their effects on each mode are discussed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.3
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• pp.339-345
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• 1998

The purpose of this paper is to investigate the effect of the specimen geometries on the pin bearing strength of the angle ply carbon fiber reinforced composites. The effect of the edge distance and the specimen width on the pin bearing strength of angle ply CFRP composites are experimentally investigated in this paper. As results, the failure mode and pin bearing strength of mechanical joints turned out to depends on the stacking sequence and specimen geometries such as the edge distance and the specimen width. The higher pin bearing strength obtained for the angle ply CFRP composites is attributed to a combination of debonding, pull out, buckling and breakage of fiber and also the matrix cracking.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3001-3006
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• 2008

Recently, the internal combustion engines have focused on reducing both the CO2 emissions in order to cope with severe regulations for greenhouse effect. Therefore, various new technologies have been developed in many countries. Among them, the cooling system is spotlighted because it has great effect on fuel efficiency. However, the present engine cooling system is almost same as one of the 50 years ago. The needs for high performance and compact size make it important to improve engine cooling system, down-sizing and control method of coolant flow. Thus, low fuel consumption technology such as control and synthetic management of cooling system was necessary to satisfy with these needs. In this study, we applied electric thermostat to improve the fuel economy. The fuel consumption was compared after driving FTP-75 mode on both conditions which were with a conventional wax thermostat and with a electric thermostat. The coolant temperature of opening the electric thermostat is higher.

• Steel and Composite Structures
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• v.30 no.6
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• pp.551-565
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• 2019

A total of 36 carbon steel and stainless steel bolted connections subjected to shear loading at different strain rates was experimentally investigated. The connection specimens were fabricated from carbon steel grades 1.20 mm G500 and 1.90 mm G450, as well as cold-formed stainless steel types EN 1.4301 and EN 1.4162 with nominal thickness 1.50 mm. The connection tests were conducted by displacement control test method. The strain rates of 10 mm/min and 20 mm/min were used. Structural behaviour of the connection specimens tested at different strain rates was investigated in terms of ultimate load, elongation corresponding to ultimate load and failure mode. Generally, it is shown that the higher strain rate on the bolted connection specimens, the higher ultimate load was obtained. The ultimate loads were averagely 2-6% higher, while the corresponding elongations were averagely 8-9% higher for the test results obtained from the strain rate of 20 mm/min compared with those obtained from the lower strain rates (1.0 mm/min for carbon steel and 1.5 mm/min for stainless steel). The connection specimens were generally failed in plate bearing of the carbon steel and stainless steel. It is shown that increasing the strain rate up to 20 mm/min generally has no effect on the bearing failure mode of the carbon steel and stainless steel bolted connections. The test strengths and failure modes were compared with the results predicted by the bolted connection design rules in international design specifications, including the Australian/New Zealand Standard (AS/NZS4600 2018), Eurocode 3 - Part 1.3 (EC3-1.3 2006) and North American Specification (AISI S100 2016) for cold-formed carbon steel structures as well as the American Specification (ASCE 2002), AS/NZS4673 (2001) and Eurocode 3 - Part 1.4 (EC3-1.4 2015) for stainless steel structures. It is shown that the AS/NZS4600 (2018), EC3-1.3 (2006) and AISI S100 (2016) generally provide conservative predictions for the carbon steel bolted connections. Both the ASCE (2002) and the EC3-1.4 (2015) provide conservative predictions for the stainless steel bolted connections. The EC3-1.3 (2006) generally provided more accurate predictions of failure mode for carbon steel bolted connections than the AS/NZS4600 (2018) and the AISI S100 (2016). The failure modes of stainless steel bolted connections predicted by the EC3-1.4 (2015) are more consistent with the test results compared with those predicted by the ASCE (2002).

• Composites Research
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• v.13 no.2
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• pp.72-80
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• 2000

Effect of graphite powder addition on the mechanical properties of carbon fiber reinforced carbon composites (C/C composites) was investigated. Greenbody (G/B) with 0~30wt.% graphite powder addition to phenol resin was prepared and carbonized at $1000^{\circ}C$ to make C/C composites. Flexural strengths of 20wt.% graphite powder additions showed maximum values in the both case of G/B and C/C composites. But, at the graphite addition over 20wt.%, there was negative effect due to the matrix inhomogeneity. Flexural strength of cured resin without graphite Powder was higher than that with graphite. However, flexural strength of carbonized resin with graphite increased three times as much as that of carbonized resin without graphite. Because the addition of graphite powder effects the restraint of shrinkage after carbonization and the deflection of crack path. In Mode II ENF test, energy release rates($G_{II}$) of G/B and C/C composites with the 20w1.% addition of graphite were both increased. But, the addition of graphite was more effective to the increase of $G_{II}$ in C/C composites than that in G/B.

• Journal of Pharmaceutical Investigation
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• v.37 no.3
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• pp.149-158
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• 2007

To investigate the permeability of lidocaine, percutaneous absorption studies were performed using excised hairless mouse skin and the penetration of lidocaine via the skin was determined. To increase the skin permeation of lidocine, the effects of $Labrasol^{(R)}$, $Labrafil^{(R)}$, $Labrafac^{(R)}$ and $Transcutol^{(R)}$ were investigated. The skin permeation of lidocaine was increased when $Labrasol^{(R)}$ and $Transcutol^{(R)}$ were used as permeation enhancer. To evaluate the influence of ultrasound, various factors such as application modes (continuous mode and pulsed mode), frequency (1.0 and 3.0 MHz) and intensity (1.0, 1.5 and 2.0 w/$cm^2$) were investigated with lidocaine hydrogel. The pronounced effect of ultrasound on the skin permeation of lidocaine was observed at all ultrasound energy levels. The influence of frequency having an effect on skin permeation rate was higher in the case of using 1 MHz, 2.0 w/$cm^2$ and continuous treatment. As the intensity of ultrasound increased, the permeation of lidocaine was accelerated. The in vivo anesthetic effects were evaluated by two aspects as mechanical threshold and electrical threshold. Six healthy volunteers consented to the randomized, double-blind, and cross-over designed study in each group. In each subject, 3 groups were adapted such as K group (ultrasound with gel base only), L group (lidocaine gel) and B group (ultrasound with lidocaine gel). In conclusion, lidocaine was potent anesthetic which could be block pain threshold effectively. And ultrasound could accelerate the skin penetration of lidocaine. The phonophoretic delivery system could be a good candidate for lidocaine as a local anaesthetic to improve the skin permeation and in vivo anaesthetic effect.

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.97-112
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• 1995

The purpose of this study was to evaluate the effect of wetting condition made by drying time on bonding of resin cement to dentin. Freshly extracted bovine teeth were grinded to expose flat dentin surfaces. After the exposed dentin surfaces were treated with pretreatment agents and water rinse, each wetting condition of dentin surfaces was made according to drying times and methods including slight blow bry for I-second by air syringe, blow dry for 20-second by air syringe, and 12-hour dry in desiccator respectively. and then, previously made composite resin specimens were bonded onto each conditioned dentin surface of the specimen using Panavia-21(Kuraray Co.), Bistite(Tokuso Co.), and Choice(use with All bond-2, Bisco Inc.) resin cement according as manufacturer's instruction. Bonded specimens were stored in $37^{\circ}C$ distilled water for 24 hours, then the tensile bond strength was measured, cohesive failure rate was calculated, and fractured dentin surfaces and acrylic rod sides were examined under scanning electron microscope. The result were as follows ; In the group of bonding with Panavia-21 resin cement, higher tensile bond strength was seen in 12-hour dry group than in I-second and 20-second dry group(p<0.01). In the group of bonding with Bistite resin cement, higher tensile bond strength was seen in 1-second dry group than in 20-second and 12-hour dry group(p<0.01). In the group of bonding with Choice resin cement, no significant differences of bond strength under given drying time were seen. Cohesive failure rates derived from the groups of bonding with Panavia-21 and Choice resin cement were increased with the increase of tensile bond strength in each drying time. On SEM examination of fractured surface, adhesive failure mode with fractured resin tags was mostly seen in wet condition with I-second drying time in the group of bonding with Panavia-21 resin cement, mixed failure mode with shortened and fractured resin tag was seen in the group of bonding with Bistite resin cement, and regardless of drying time, and cohesive-adhesive mixed failure mode with fracture of 'Hollow' typed resin tags was mainly seen in the group of bonding with Choice resin cement.