• The Journal of Korean Academy of Prosthodontics
• /
• v.43 no.2
• /
• pp.149-157
• /
• 2005

Statement of problem. Dental ceramics exhibit excellent esthetic property, compressive strength, chemical durability biocompatibility and translucency. However, it suffers from inherent brittle fractures. Various techniques and materials for intraoral porcelain repair has been suggested. Purpose. This study is to compare the tensile bond strength of four commonly used porcelain repair systems (Vivadent, Bisco, Ulttadent, Voco) and to insure the best system for the clinical application to the fractured porcelain. Materials and methods. A total of fifty specimens were fabricated. Specimens were stored in $37^{\circ}C$ distilled water for 7 days and thermocycling was performed(1000 cycles), and subjected to a tensile force parallel to the repair resin and porcelain interface by use of an Universal Testing Machine. Result. 1. Voco showed the highest tensile bond strength. In decreasing order, the tensile bond strength of the other materials was as follows : Ultradent, Bisco, Vivadent. 2. There was a statistically significant difference between the porcelain repair systems(Voco, Ultradent > Bisco, Yivadent) (p<0.05). 3. SEM examination of prepared porcelain surfaces revealed that the surface treated with Voco showed brittle fracture. However, Ultradent, Bisco and Vivadent showed ductile fracture. 4. All specimens treated with four porcelain repair systems showed adhesive failure between porcelain and composite resin.

• Korean Journal of Metals and Materials
• /
• v.48 no.4
• /
• pp.289-296
• /
• 2010

The effects of heat input and different microstructureswere investigated on the tensile-shear properties of an arc-brazed joint of theferritic stainless steel 429EM using a Cu-Si insert alloy. The brazing speed was fixed at 800 mm/min whilethe brazing current varied from 80 to 120A. For abrazing current lower than 100A, fracturing occurred at the joint root in the direction perpendicular to the tensile load. As the brazing current increased to 120A, fracturing occurred at the base metal or the joint root. The joint and the base metal had very similar yield and tensile load values. However, the amount of elongation was decreased considerably compared to when the base metal was used. The fracturing began at the triple point of the root part and was classified into three types. The difference in the tensile-shear properties was closely related to the three fracture types.

• Korean Journal of Materials Research
• /
• v.24 no.9
• /
• pp.481-487
• /
• 2014

The effect of alpha phase on the fatigue properties of Fe-29%Ni-17%Co low thermal expansion alloy was investigated. Two kinds of alloys (Base alloy and Alpha alloy) were prepared by controlling the minimal alloy composition. Microstructure observation, tensile, high-cycle fatigue, and low-cycle fatigue results were measured in this study. The Base alloy microstructure showed typical austenite ${\gamma}$ phase. Alpha alloy represented the dispersed phase in the austenite ${\gamma}$ matrix. As a result of tensile testing, Alpha alloy was found to have higher strengths (Y.S. & T.S.) and lower elongation compared to those of the Base alloy. High cycle fatigue results showed that Alpha alloy had a higher fatigue limit (360MPa) than that (330MPa) of the Base alloy. The Alpha alloy exhibited the superior high cycle fatigue property in all of the fatigue stress conditions. SEM fractography results showed that the alpha phase could act to effectively retard both fatigue crack initiation and crack propagation. In the case of low-cycle fatigue, the Base alloy had longer fatigue life in the high plastic strain amplitude region and the Alpha alloy showed better fatigue property only in the low plastic strain amplitude region. The fatigue deformation behavior of the Fe-29%Ni-17%Co alloy was also discussed as related with its microstructure.

• Journal of Fashion Business
• /
• v.10 no.1
• /
• pp.120-131
• /
• 2006

Recently, it has been reported that chemical hair coloring can cause allergic reactions, the toxicity issue of chemical hair color was issued. Therefore, there is an increasing interest in the hair coloration technique using non-toxic and bio-compatible hair color gotten from natural resource. In this study, the possibility using fermented Indigo as natural hair coloring agent was investigated. Bleached hair samples were dyed using Indigo, and the effect of dyeing frequency, the physical change after dyeing, color, surface and cross-section characteristics, and tensile property were also studied. In addition, the protection property of cationic detergent finishing on damaged hair samples were also studied. The following conclusions are made; 1. While bleached hair samples with low value showed the negligible effect of repeated dyeing, bleached hair samples with high value showed the good effect of repeated dyeing. 2. Hair sample dyed with Indigo showed a high light-fastness, however, tensile strength and elongation showed very low values (high damage on hair sample). 3. Cationic detergent finishing did not affect on the colorfastness because of decoloration after dyeing, however, it increased the smoothness of hair sample, and therefore, can use as protectant of damaged hair. 4. Hair scale was damaged after dyeing. It seemed that the alkali, potassium carbonate, increased pH of dyeing bath to 11, as a result, the hair was swollen, weaken, and dissolved on the prolonged dyeing time. Dyed hair sample became stiff and fine. 5. The color difference was 4.62 (a high fastness value) in the test of sunlight exposure, shampoo, cationic detergent finishing, and acid perspiration fastness.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.5
• /
• pp.584-590
• /
• 2012

The structural and functional disorder of a detrusor induces a bladder hypertrophy and degenerates a bladder muscle gradually by preventing normal urination. Thus, the thickness of the bladder wall has been increased in proportion to the degree of bladder outlet obstruction. In this study, the mechanical characteristics of the detrusor is analyzed for the physical properties and the thickness changes of the bladder muscle using a mathematically analytic method. In order to obtain the mechanical property of the bladder muscle, the tensile test of porcine bladder tissue is performed because its property is similar to that of human. The result of tensile test is applied to the mathematically model as Mooney Rivlin coefficients which represent the hyperelastic material. The model of the bladder is defined as the spherical shape with the initial volume of 50ml. The principal stress and strain according to the thickness are analyzed. Also, computer simulations for three types of the material property for the model of the bladder are performed based on the fact that the stiffness of the bladder is weakened as the progress of the benign prostatic hyperplasia. As a result, the principal stress is 341kPa at the initial thickness of 2.2mm, and is 249kPa at 6.5mm. As the bladder wall thickness increases, the principal stress decreases. The principal stress and strain decrease as the stiffness of the bladder decreases under the same thinkness.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.42 no.2
• /
• pp.41-45
• /
• 2010

This study was performed to evaluate the effect of paper property changes by internal addition of surface strength agent on printability. Advances in printing technique has required the development of paper qualities in many aspects. Basically paper structure is composed of hydrogen bonds which induce many problems in high speed printing machine because of weak bonding strength. One of the important printing problems is surface picking when mechanical pulp or recycled pulp are used. It was caused by the ink-stained blanket in printing process because accumulations of pollutant in white water and other elements which are bonded weakly or do not have hydrogen bonds. Debris at paper surface adheres to blanket which deteriorates printing efficiency and causes various problems. To complement these problems, Pennocel 5137 of polysaccharide structure was used as an agent to improve paper's surface property, strength and printability. Paper surface picking was analyzed by RI-1 test. As the dosage amount increased tensile strength, fiber bonding strength and ZDT strength were improved. Further more formation, smoothness and surface picking resistance were improved. It was confirmed that when adding polysaccharide structure polymers to improve surface strength such as surface picking resistance, it was also possible to improve tensile strength, fiber bonding strength, formation and smoothness.

• Journal of Korea Foundry Society
• /
• v.25 no.2
• /
• pp.73-79
• /
• 2005

Effects of Cr and Ni addition on damping capacity, mechanical property, and corrosion resistance of Fe-17%Mn martensitic alloy have been studied. Martensite start temperature($M_{S}$) of the alloy decreases linearly with increasing Cr and Ni contents up to 15%. The damping capacity decreases gradually from 27 to 22% in specific damping capacity(SDC) with increasing Cr and Ni contents from zero to 10%, and decreases rapidly with further Cr and Ni content in Fe-17%Mn alloy. The tensile strength of the alloy maintains a level of 60 $kgf/mm^{2}$ regardless of Cr content with an elongation of 20 to 25%. But, in case of Fe-17%Mn-x%Ni alloy, the tensile strength decreased rapidly with the Ni content of above 10% because of austenite morphology. Immersion test in 5% NaCl solution leads to the result that the corrosion resistance of the alloy becomes excellent above 10% Cr. From the above results, it is concluded that the optimum Cr content to improve the mechanical property and corrosion resistance of the alloy in 5%NaCl solution with a lesser decrease in damping capacity is about 10%. In the case of 5% $H_{2}SO_{4}$ condition, the Fe-17%Mn-10%Ni is an optimum alloy.

• Journal of Korea Foundry Society
• /
• v.35 no.3
• /
• pp.45-52
• /
• 2015

The effect of different C and Cr/Mo contents, which were varied within the range allowed in the relevant specification, on the mechanical and corrosion properties of A487 alloy cast steel were examined. The increase in strength level with increasing C content and the decrease in strength along with the increase in tensile elongation with decreasing Cr/Mo contents were observed in A487 alloys with different C and Cr/Mo contents. At room temperature, the decrease in Cr/Mo content was beneficial in improving the impact properties of A487 alloy, with no notable difference in absorbed energy with varying C content. The impact properties of A487 alloy at $-60^{\circ}C$, on the other hand, greatly improved with the increase in C and the decrease in Cr/Mo contents. The corrosion behavior of A487 alloys in 3.5% NaCl solution did not show any meaningful change with different C and Cr/Mo contents.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.35 no.3
• /
• pp.191-196
• /
• 2022

In this study, the anisotropic mechanical property of fused deposition modeling three-dimensional (3D) printing based on lamination direction was verified by a tensile test. Moreover, the property was applied to solid isotropic materials with penalization-based topology optimization. The case of the lower control arm, one of the automotive suspension components, was considered as a benchmark problem. The optimal topological results varied depending on the external load and anisotropic property. Based on these results, two test specimens were fabricated by varying the lamination direction of 3D printing; a tensile test utilizing 3D non-contact strain gauge was also conducted. The measured strain was compared with that obtained by computer-aided engineering response analysis. Quantitatively, the measurement and analysis results are found to have good agreement. The effectiveness of topology optimization considering the lamination direction of 3D printing was confirmed by the experimental result.

• The International Journal of Costume Culture
• /
• v.8 no.1
• /
• pp.23-31
• /
• 2005

Mechanical properties and hand evaluation of wool/acrylic(W/A) blend knits were conducted before and after repeated washing to get the optimum W/A blending ratio, which could help achieve the optimum mechanical and hand properties of the knits. The five test fabrics using the yarns with different W/A blending ratios($\%$), 100/0, 70/30, 50/50, 30/70, 0/100, were knitted. The fabrics were washed by a rotating drum type washing machine. Then, objective mechanical and hand properties were evaluated by KES-FB, Kawabata evalution system for fabric. The results are as follows: there was no change in the hand value of the knitted fabric with the W/A-blended yarn caused by the change in the blending ratio before washing. After washing, however, the increase of acrylic's blending rate caused the bending property to decrease proportionally, while the friction coefficient of the surface property increased. Furthermore, the study showed that W/A 50/50 possesses the most superior tensile property and shearing property, which could attain the optimum blending ratio. Similar results in hand value were derived in all the samples. After washing, however, the increase in acrylic's blending rate caused a proportional decrease in KOSHI and an increase in FUKURAMI. In addition, W/A 50/50 gained the biggest NUMERI value, again corresponding to the optimum blending ratio. Similar results in total hand value were derived in all the samples before washing. After washing, though, all the total hand values decreased, and, as the wool fabric's blending rate increased, the total hand values proportionally decreased further.