• The korean journal of orthodontics
• /
• v.22 no.3 s.38
• /
• pp.591-602
• /
• 1992

The purpose of this study was to evaluate the effect of heat treatment on physical properties of 0.016' and 0.016' x 0.022' stainless steel wires. Temperature of heat treatment had intervals of $50^{\circ}C$ from $400^{\circ}C$ to $700^{\circ}C$, and time of heat treatment were 3, 6 and 9 minutes. Tensile tests were measured by ultimate tensile strength and yield strength. Bending tests were assessed by maximum bending force, recovery force, and stiffness. Torsion test was evaluated by torsion cycle until wires were fractured. The results were as follows: 1. In round wires, the highest value of ultimate tensile strength and yield strength were recorded of heat treatment at $500^{\circ}C$. In rectangular wires, the highest value of ultimate tensile strength were after 9 minutes at $400^{\circ}C,\;450^{\circ}C$ and 3, 6 minutes of heat treatment at $50^{\circ}C$, yield strength were the highest value after 3, 6 minutes of heat treatment at $500^{\circ}C$. 2. In both round and rectangular wires, maximum bending force and recovery force were the highest values after 6 minutes of heat treatment at $500^{\circ}C$. In round wires, highest value of stiffness were formed after 9 minutes at heat treatment at $500^{\circ}C$. In rectangular wires, the highest value of stiffness were for 6 minutes in $500^{\circ}C$. 3. In rectangular wires, torsion cycle was minimum after 6 minutes of heat treatment at $500^{\circ}C$. 4. In all of tension, bending, and torsion tests, the heat treated wires were softened over at $700^{\circ}C$. 5. In all of tension, bending, and torsion tests, physical properties of the wires were more influenced by the temperatures than the duration of the heat treatment.

• Journal of Ocean Engineering and Technology
• /
• v.25 no.6
• /
• pp.49-55
• /
• 2011

In order to analyze feasibility of replacing a conventional 6-mm Ti bar with a 5-mm bar, a series of rotating bending fatigue tests were carried out on Ti-6Al-4V bars by strengthening the fatigue performance using a special technique called UNSM (Ultrasonic Nanocrystal Surface Modification). The results of S-N curves clearly showed that the performance of the 5-mm titanium specimen was similar to that of the 6-mm specimen when the UNSM treatment was applied. The 5-mm treated specimen converged with small scattering band into the linear line of the non-treated 6-mm one. Below the fatigue life of $10^5$ cycles, the UNSM treatment did not show any significant superiority in the bending stress and fatigue life. However, over the fatigue life of $10^5$ cycles, the effect of UNSM was superior for each fatigue life, and the bending stress became longer and higher than that of the untreated one. In the case of 6-mm Ti-bar with UNSM, the fatigue limit was about 592 MPa, and there was fatigue strength increase of about 30.7% at the fatigue life of $10^4$ cycles compared to the untreated 6-mm bar. Therefore, the compressive residual stress made by the UNSM in Ti-6Al-4V increased the fatigue strength by more than 30%.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.24 no.4
• /
• pp.92-98
• /
• 1982

The major objective of this study was to investigate the heat resistance of epoxy resin mortar. For this purpose, these tests of compressive and bending strength were accomp- olished with various heating temperature (40˚C, 60˚C, 80˚C, 100˚C, 120˚C), and with various mixing ratio (1: 2, 1: 4, 1: 6, 1: 8, 1:10, 1:12, 1:14). The exprimental resin was to be Epi-Bis type epoxy resin, which is widely used as construction materials. The results obtained are summarized as follows; 1. The variations of color tone started to begin at 60˚C, and it has come out very heavy at 120˚C. It was assumed that the decrement of weight resulted from carbonization were about 0.22% at 100˚C, and about 0.34% at 120˚C. 2. The compressive and bending strength were increased with temperature rise up to 80˚C, but these were made rapid decrease when the given temperature was over. And so, the mean decrement of compressive and bending strength at 120˚C reached up to 35.5% and 26.4%, respectively. 3. The regression equation between compressive and bending strength for epoxy resin mortar under heat exposure were obtained as follows; od=0. 371oc+39. 23 (r=0. 986) And the estimated value of bending strength was corresponded to about 37 percent in comparing with that of the compressive strength. 4. Consquently, the heat resistance temperature of epoxy resin mortar was to be around 80˚C, and it was generally very low values. But it was regarded that the epoxy resin mortar will not be difficult with materials of civil engineering works and agricultural structures.

• Steel and Composite Structures
• /
• v.44 no.2
• /
• pp.199-210
• /
• 2022

This study build finite element analysis (FEA) models describing the bending events of coiled tubing (CT) at the wellhead and trips into the hole, accurately provide the state of stress and strain while the CT is in service. The bending moment and axial force history curves are used as loads and boundary conditions in the diametrical growth models to ensure consistency with the actual working conditions in field operations. The simulation diametrical growth results in this study are more accurate and reasonable. Analysis the factors influencing fatigue and diametrical growth shows that the internal pressure has a first-order influence on fatigue, followed by the radius of the guide arch, reel and the CT diameter. As the number of trip cycles increase, fatigue damage, residual stress and strain cumulatively increase, until CT failure occurs. Significant residual stresses remain in the CT cross-section, and the CT exhibits a residual curvature, the initial residual bending configuration of CT under wellbore constraints, after running into the hole, is sinusoidal. The residual stresses and residual bending configuration significantly decrease the buckling load, making the buckling and buckling release of CT in the downhole an elastic-plastic process, exacerbating the helical lockup. The conclusions drawn in this study will improve CT models and contribute to the operational and economic success of CT services.

• Journal of the Society of Disaster Information
• /
• v.7 no.1
• /
• pp.43-50
• /
• 2011

The Application of Steel Fiber Shotcrete in tunneling construction has become part of tunneling practice at least since the 1970s because of its high bending and tensile properties. Over the past 3 decades, researcher from all over the world have been significantly developing the associated technologies for improved performance of SFRS. But still it has some major drawbacks in terms of durability, damage of pumping hose, wastage due to rebound concrete, corrosion and it costs high. To overcome this situation researcher has to look for some alternative material. Therefore, this part study deals with the three types of fiber in order to find good alternative for steel fiber. Polyamide and Polypropylene fiber were used in this study with 0.6, 0.5% mixing ratio. To evaluate its fresh and harden properties air content, slump, compressive, split tensile and bending strength were measured. After comparing the results of all three types of fiber reinforced concrete with its different mixing proportion this study propose that polyamide fiber with addition ratio of 0.6 % for field use.

• Korean Journal of Radiology
• /
• v.1 no.2
• /
• pp.65-72
• /
• 2000

Objective: To compare the efficacy of suprapapillary and transpapillary methods of transhepatic biliary metallic stent placement in malignant biliary strictures and to specify the indications of each method applied. Materials and Methods: Stents were placed in 59 patients. Strictures were categorized as type A (within 3 cm of the ampulla, n = 27), type B (over 3 cm from ampulla, n = 7), type C (within 3 cm of the bending portion, n = 9), or type D (over 3 cm above the bending portion, n=16). The stenting method was suprapapillary in 34 cases and transpapillary in 25. The rates of initial and long-term patency and of early recurrence were compared. Results: Initial patency rates for the suprapapillary and transpapillary methods were 1/7 (14.3%) and 20/20 (100%) respectively for type A (p < 0.0001), 4/5 (80.0%) and 2/2 for type B, 3/7 (42.9%) and 2/2 for type C, and 15/16 (93.8%) and 0/0 for type D. Early recurrence rates were 7/30 (23.3%) using the suprapapillary method and 4/29 (13.8%) using the transpapillary method (p = 0.51). The long-term patency rate did not differ significantly according to either type (p = 0.37) or method (p = 0.62). Conclusion: For good initial patency, the transpapillary method is recommended for strictures of the distal extrahepatic duct near the ampulla and just above the bending portion. Long-term patency is not influenced by the stenting method employed.

• The International Journal of Costume Culture
• /
• v.4 no.2
• /
• pp.77-85
• /
• 2001

The purpose of this study was to classify the somatotype around a upper body of 30's men. The subjects were 202 working men aged from 30 to 39 and the data of 33 items including computed items were analysed by factor analysis and cluster analysis. Re results were as follows: As a factor of somatotype in evaluating males in 30's, the horizontal area represented the chest circumference at scye and the breadth items, the vortical region indicated hit length posterior, front length, back length, the breadth difference and the length difference. The somatotype by cluster analysis was classified with 3 type. Type I as the Roher's index 1.21 indicating the smallest in the circumference and weight item was classified as the thin and long featuring bending somatotype. Type 2 with the Rohrer's index 1.35 showing the mid-group between type 1 and 3 had the highest distribution rate as the balanced featuring the standard somatotype. Type 3 as the rohrer's index 1.40 was the largest physical condition group in the obesity featuring the turning over somatotype.

• Structural Engineering and Mechanics
• /
• v.48 no.6
• /
• pp.833-848
• /
• 2013

Nine rectangular-section of High Strength Concrete(HSC) beams were designed and casted based on the American Concrete Institute (ACI) code provisons with varying of tensile reinforcement ratio as (${\rho}_{min}$, $0.2_{{\rho}b}$, $0.3_{{\rho}b}$, $0.4_{{\rho}b}$, $0.5_{{\rho}b}$, $0.75_{{\rho}b}$, $0.85_{{\rho}b}$, $_{{\rho}b}$, $1.2_{{\rho}b}$). Steel and concrete strains and deflections were measured at different points of the beam's length for every incremental load up to failure. The ductility ratios were calculated and the moment-curvature and load-deflection curves were drawn. The results showed that the ductility ratio reduced to less than 2 when the tensile reinforcement ratio increased to $0.5_{{\rho}b}$. Comparison of the theoretical ductility coefficient from CSA94, NZS95 and ACI with the experimental ones shows that the three mentioned codes exhibit conservative values for low reinforced HSC beams. For over-reinforced HSC beams, only the CSA94 provision is more valid. ACI bending provision is 10 percent conservative for assessing of ultimate bending moment in low-reinforced HSC section while its results are valid for over-reinforced HSC sections. The ACI code provision is non-conservative for the modulus of rupture and needs to be reviewed.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.15 no.3 s.39
• /
• pp.309-320
• /
• 1991

The purpose of this study was to develope a pattern drafting method for various somatotype which contribute largely to increase the fitness and comfort of garments. This study had 8 subjects who were college girls who had prominent somatic characteristics. The study was carried out by the following procedures. 1. The 8 subjects who had prominent somatic characteristics were cheesed by photograph- ing. The somatotypes of 8 subjects were classified into Standard somatotype, Turning over somatotype, Bending somatotype and Turning over-Bending somatotype. 2. Under the criterion of the body surface development, the comparative investigation on the pattern and the sensory evaluation were accomplished in the flat pattern method and the draping pattern method. 3. The body surface development of them were made by the draping pattern method. 4. In the result of the comparative investigation and the sensory evaluation, it was found that the flat pattern had better appearance and comfort than the draping pattern, and the draping pattern included more somatic characteristics than the flat pattern. 5. On the basis of those result, the pattern drafting method according to the somatotype was indicated and it was examinated by the clothing experiment. 6. The sensory evaluation for appearance and comfort was applied to evaluate the new basic pattern for four somatotype by comparing it with the conventional basic pattern (Rim, won ja' 5). The result of the sensory evaluation, it was found that the new basic pattern was more suitable for each somatotype than the conventional basic pattern.

• Journal of the Korean Society of Costume
• /
• v.14
• /
• pp.199-208
• /
• 1990

In order to eximine the body form of the physically handicapped people, the 11 items of angle, 54 items of size and weight of the subjects were measured body silhouetter photographs and with the Martin's anthrophometeric instrument respectively. The subjects were consist of 37 boy students who are 13-19 years old and hemiplegias caused by cerebral palsy. And then the comparison between normal and paralysis sides, analysis of somatotypes with the body silhouetter photographs, ANOVA for effect of somatotype on measuring items for angles, and factor analysis for all items were carried out. The results were as follows: 1. The results of measuring are difference between normal and paralysis sides. 2. The items shown significant differences between normal and paralysis sides are diagonal anterior chest B, scapula length, armscye girth, diagonal posterior chest A, and arc of the bust. 3. The percentage of each somatotype shows the order of bending somatotype, turning over somatotype, turning over-bending somatotype, and standard somatotype in the upper body. There are significant differences between somatotypes and sternalis up, sternalis down, scapula, vertebialis, ${\alpha}$, and ${\beta}$ angles respectively. 4. From the result of factor analysis, front and back sections, length items of the upper part and the lower part from the bust line, and the upper size items at the bottom of armscye were abstracted.