• Structural Engineering and Mechanics
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• 제42권5호
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• pp.701-713
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• 2012

Results pertaining to 3D investigations on the effect of the thickness on the stress fields at the crack front are presented. A 3D finite element analysis is performed using a modified single edge-notched tension specimen configuration, with an inclined crack to include mixed mode I-II. A technique to mesh the crack front (3D) with singular finite elements in ANSYS without using third party software is introduced and used in this study. The effect of the specimen thickness is explicitly investigated for six thicknesses ranging from 1 to 32 mm. In addition, three crack inclination angles, including pure Mode-I, are used to study the effect of mixed-mode I-II fracture. An attempt is made to correlate the extent of a particular stress state along the crack front to thickness. In addition, ${\sigma}_{zz}/{\nu}({\sigma}_{xx}+{\sigma}_{yy})$ contours at the crack front are presented as a useful means to analyze the stress state.

• Journal of Ceramic Processing Research
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• 제20권5호
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• pp.499-504
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• 2019

The effect of coating thickness on the contact fatigue and wear of thermal barrier coatings (TBCs) are investigated in this study. The same bondcoat material thickness (250 ㎛) are used for each sample, which allows the effect of the coating thickness of the topcoat to be investigated. TBCs with different coating thicknesses (200, 400, and 600 ㎛) are prepared by changing processing parameters such as the feeding rate of the feedstock, spraying speed, and spraying distance during APS(air plasma spray) coating. The damage size on the surface are strongly affected by the coating thickness effect. Although the damage size from contact fatigue using a spherical indenter diminish at a TBC of 200 ㎛, a high wear resistance such as a low friction coefficient and little mass change are found at a TBC of 600 ㎛. These results indicate that the coating thickness strongly affects the mechanical behavior in TBCs during gas turbine operation.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.8-9
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• 2020

In this study, the electrical conductivity and shielding effect were evaluated according to the type of metal and the thickness of Metal sprayed coating. The metals used for the test are Cu, Cu-Ni and Cu-Zn, and the thicknesses were 100, 200, 500 um. Each metal sprayed coating was evaluated for electrical conductivity and electromagnetic shielding effect. When the thickness was 200 ㎛ or more, shielding effect 80 dB or more was satisfied at 1 GHz. However, in the case of Cu-Ni, there is little electrical conductivity at a thickness of 100 um or less due to the generated voids, and electromagnetic wave shielding performance cannot be expected. Therefore, To ensure electromagnetic shielding effect of structures, it is considered that the minimum thickness of metal spraying coating should be 200 um.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.339-342
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• 2003

The bridge columns with lap-splice reinforcements in earthquake suffered a brittle bond-slip failure due to deterioration of the lap-spliced longitudinal reinforcements without developing its flexural capacity or ductility. In this case, such a brittle failure can be controlled by the seismic retrofit using FRP wrapping. The retrofitted columns using FRP wrapping showed significant improvement in seismic performance due to FRP's confinement effect. This paper presents the circumferential confinement effect of existing circular bridge pier strengthened with FRP wrapping for poor lap-splice details. The effects on the confinement of FRP wrapping, such as gap lengths between footing and FRP, fiber orientations, and thicknesses of FRP, were investigated by quasi-static experiments.

• Journal of Magnetics
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• 제6권1호
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• pp.9-12
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• 2001

The dependence of the magnetoimpedance effect (MI) on magnetic properties has been investigated in mumetal thin films prepared by rf magnetron sputtering. Coercivity of thin films prepared at 400 W was about 0.4 Oe, and the magnetic anisotropy field of films deposited under a uniaxial magnetic field decreased with increasing film thickness. The saturation magnetization of mumetal films increased with rising input power and thickness and was smaller than that of permalloy films. Transverse incremental Permeability (TPR) of films of 1$\mu m$ thick increased with increasing effective permeability. The magneto impedance ratio (MIR) was proportional to TPR in films 1$\mu m$ thick but in spite of lower effective permeability at higher thicknesses, MIR increased due to skin effect. The height of the double peaks in the MIR curves decreased with decreasing anisotropy and thickness. The maximum MIR value for a 4$\mu m$ thick 75% at 36.5 MHz.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.520-525
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• 2003

Supersonic jet issuing from a nozzle invariably cause high-frequency noises. These consist of three principal components ; the turbulent mixing noise, the broadband shock-associated noise, and the screech tone. In present study, it was experimentally investigated to the effect of nozzle lip thickness on the characteristics of supersonic jet noise. The convergent-divergent nozzle of a design Mach number 2.0 was used in experiment. With three different nozzle-lip thicknesses, the jet pressure ratio was varied in the range between 2.0 and 12.0. Acoustic measurements were conducted by microphones in an anechoic room, and the major structures of the supersonic jets were visualized by a Schlieren optical system to investigate the effect of nozzle lip thickness. The measured results show that the characteristics of supersonic jet noise, such as overall sound pressure level (OASPL) and screech frequency, strongly depend upon the thickness of nozzle-lip.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.280-287
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• 2003

The bridge columns with lap-splice reinforcements in earthquake suffered a brittle bond-slip failure due to the deterioration of lap-spliced longitudinal reinforcement without developing its flexural capacity or ductility. In this case, such a brittle failure can be controlled by the seismic retrofit using FRP wrapping. The retrofitted columns using FRP laminated circular tube showed significant improvement in seismic performance due to FRP's confinement effect. This paper presents the circumferential confinement effect of existing circular bridge pier strengthened with FRP wrapping for poor lap-splice details. The effects on the confinement of FRP wrapping, such as gap lengths between footing and FRP, fiber orientations, and thicknesses of FRP, were investigated by Quasi-static experiments.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3390-3397
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• 2022

Among the different techniques available, nuclear methods, including gamma-gamma logging tools, are of special importance. Though the real environment which surrounds the drilled borehole is a complex fractured medium which the fluid can flow through the porosities, simulation studies generally use the traditional model of a homogeneous mixture of formation and the liquid. Considering a previously published study, which shows that modeling of fluid flow in fractured reservoirs and simulating the formation as an inhomogeneous fractured medium leads to different results compared with those of homogeneous mixture, here we study the effect of the presence of drilling fluid (mudcake) on the response of the detectors in both the models. To study this effect, a typical gamma-gamma logging tool was modeled by using the MCNPX Monte Carlo code. The results show that the responses of the detectors in the mixture model in the presence of various thicknesses of mudcake are sensitive to the density of the formation material. However, this effect is not notable in the inhomogeneous fractured medium. These results emphasize the importance of the model employed for simulation of the medium in gamma-gamma well-logging.

• The Journal of Advanced Prosthodontics
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• 제7권5호
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• pp.368-374
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• 2015

PURPOSE. The aim of the study was to evaluate the effect of abutment shade, ceramic thickness, and coping type on the final shade of zirconia all-ceramic restorations. MATERIALS AND METHODS. Three different types of disk-shaped zirconia coping specimens (Lava, Cercon, Zirkonzahn: ${\phi}10mm{\times}0.4mm$) were fabricated and veneered with IPS e.max Press Ceram (shade A2), for total thicknesses of 1 and 1.5 mm. A total of sixty zirconia restoration specimens were divided into six groups based on their coping types and thicknesses. The abutment specimens (${\phi}10mm{\times}7mm$) were prepared with gold alloy, base metal (nickel-chromium) alloy, and four different shades (A1, A2, A3, A4) of composite resins. The average $L^*$, $a^*$, $b^*$ values of the zirconia specimens on the six abutment specimens were measured with a dental colorimeter, and the statistical significance in the effects of three variables was analyzed by using repeated measures analysis of variance (${\alpha}$=.05).The average shade difference (${\Delta}E$) values of the zirconia specimens between the A2 composite resin abutment and other abutments were also evaluated. RESULTS. The effects of zirconia specimen thickness (P<.001), abutment shade (P<.001), and type of zirconia copings (P<.003) on the final shade of the zirconia restorations were significant. The average ${\Delta}E$ value of Lava specimens (1 mm) between the A2 composite resin and gold alloy abutments was higher (close to the acceptability threshold of 5.5 ${\Delta}E$) than th ose between the A2 composite resin and other abutments. CONCLUSION. This in-vitro study demonstrated that abutment shade, ceramic thickness, and coping type affected the resulting shade of zirconia restorations.

• Archives of Plastic Surgery
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• 제40권6호
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• pp.697-704
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• 2013

Background We conducted an experimental study to compare the effect of massage using topical agents (Kelo-cote or Contractubex) on scar formation by massaging the healed burn wound on the dorsal area of Sprague-Dawley (SD) rats. Methods Four areas of second degree contact burn were made on the dorsal area of each of 15 SD rats, using a soldering iron 15 mm in diameter. After gross epithelialization in the defect, 15 SD rats were randomly divided into four groups: the Kelo-cote group, Contractubex group, Vaseline group, and control group. Rats in three of the groups (all but the Control group) were massaged twice per day for 5 minutes each day, while those in the Control group were left unattended. For histologic analysis, we performed a biopsy and evaluated the thickness of scar tissue. Results In the Kelo-cote and Contractubex groups, scar tissue thicknesses showed a significant decrease, compared with the Vaseline and control groups. However, no significant differences were observed between the Kelo-cote and Contractubex groups. In the Vaseline group, scar tissue thicknesses showed a significant decrease, compared with the control groups. Conclusions The findings of this study suggest that massage using a topical agent is helpful in the prevention of scar formation and that massage only with lubricant (no use of a topical agent) also has a considerable effect, although not as much as the use of a topical agent. Thus, we recommend massage with a topical agent on the post-burn scar as an effective method for decreasing the scar thickness.