• Journal of the Korean Institute of Gas
• /
• v.19 no.1
• /
• pp.6-11
• /
• 2015

This paper is to study the examples for rubber damage and weaken reliability of timing belt, constant velocity joint boot and weather strip in vehicle. The first example, when the service man replaced the new timing-belt of rubber material, he assembled the belt that was weaken it's contact surface because of material transform. He knew the abnormally tearing failure by friction action between belt and sprocket. The second example, it certified the fact that the grease is leaked out boot protecting of constant velocity joint by split of rubber surface because of durability badness. The third example, the weather stripe took the minutely tearing because of damage produced the material transform by crack of chemistry change. It certified the production phenomenon of a tiny noise by coming with outside air because of overlapped the rubber of weather stripe when driving after closing the door. Therefore, the driver must always manage the rubber system part of vehicle.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.7
• /
• pp.635-643
• /
• 2017

The purpose of this study is to investigate the influence of the cold reduction rate and an ultrasonic fatigue test (UFT) on the fatigue behaviors of STS 304L. The tensile strength, yield strength, hardness value and fatigue limit in the UFT fatigue test linearly increased as thickness decreased from 1.5 mm to 1.1 mm, as the cold reduction rate of STS 304L increased. As a result of the UFT fatigue test (R = -1) of four specimens, the fatigue limit of the S-N curve formed a knee point in the region of $10^6$, and the 2nd fatigue limit caused by giga cycle fatigue did not appeared. In the case of t = 1.1 mm, the highest fatigue limit was 345 MPa, which was 64.3% higher than the original material (t = 1.5 mm). As a result of the UFT fatigue test of STS 304L, many small surface cracks occurred, grown, coalesced while tearing.

• Journal of Korean Society of Steel Construction
• /
• v.21 no.1
• /
• pp.63-70
• /
• 2009

Failure modes result in fracture or tearing, which may cause deterioration of resistance and reduction of inelastic deformation capacity. The potential failure modes for Special Concentrically Braced Frames (SCBFs) include fracture or tearing of the brace, net section fracture of the brace or gusset plate, fracture of the gusset plate welds, shear fracture of the bolts, block shear, excessive bolt bearing deformation, and buckling of the gusset plate. HSS tubular braces are commonly used in SCBFs, and net section fracture of the tubular brace may also occur through the brace net section at the end of the slot cut into the tube to slip over the gusset plate. This failure mode is categorized as a tension failure mode, and may cause dramatic loss of resistance and brittle behavior. Net section reinforcement is required according to AISC design specifications (AISC 2001). In this paper, the need to reinforce the net section area was discussed. Initially, the results of the net section fracture tests done by the University of California in Berkeley were presented with the modeling of these tests using FE models. To investigate the possibility of net section fracture in an actual frame, the slot end hole model was adapted to the frame FE model, and alternate near-fault histories were applied with tension-dominated cycles, since previous analyses showed that loading history was the most critical factor in net section fracture. The need for this reinforcement (cover plate) and the tension-dominated near-fault history were investigated.

• Journal of Korean Ophthalmic Optics Society
• /
• v.16 no.3
• /
• pp.237-245
• /
• 2011

Purpose: The present study was conducted to investigate whether certain repeated physical and/or chemical stimuli added on ophthalmic lenses might induce any changes of the functions of lens coatings. Methods: The changes in lens surface, light transmittance, foggy duration, durability of ophthalmic lenses were determined after the application of tearing-off with tape, rubbing with acetone, soaking in acetone or distilled water of ophthalmic lens (CR-39 material) as physical and/or chemical stimuli. Results: The change of ophthalmic lens surface was detected after soaking in acetone for longer than 30 minutes by observing the lens surface to figure out the functional change of hard coating. The ophthalmic lens soaked in distilled water for 180 minutes showed little functional change of anti-reflection coating as 1% by measuring light transmittance of lens. However, the function of anti-reflection coating was almost disappeared after the ophthalmic lens was soaked in acetone for 60 minutes. The foggy duration of ophthalmic lens soaked in acetone was increased by estimating foggy duration of lens. The lens coating was shown to be defected when the pre-damaged ophthalmic lenses were torn off with tape, rubbed with acetone and soaked in distilled water or acetone by observing pre-damaged lens surface to evaluate its durability. Conclusions: The careful management during ophthalmic lens dispensing or usual eyeglass wearing is needed since the change in ophthalmic lens coatings was shown by repeated physical and/or chemical stimuli.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.35 no.5
• /
• pp.249-257
• /
• 2022

This paper presents an improved computational framework for the direct-solution-based finite element tearing and interconnecting (FETI) algorithm. The FETI-local algorithm is further improved herein, and localized Lagrange multipliers are used to define the interface among its subdomains. Selective inverse entry computation, using a property of the Boolean matrix, is employed for the computation of the subdomain interface stiffness and load, in which the original FETI-local algorithm requires a full matrix inverse computation of a high computational cost. In the global interface computation step, the original serial computation is replaced by a parallel multi-frontal method. The performance of the improved FETI-local algorithm was evaluated using a numerical example with 64 million degrees of freedom (DOFs). The computational time was reduced by up to 97.8% compared to that of the original algorithm. In addition, further stable and improved scalability was obtained in terms of a speed-up indicator. Furthermore, a performance comparison was conducted to evaluate the differences between the proposed algorithm and commercial software ANSYS using a large-scale computation with 432 million DOFs. Although ANSYS is superior in terms of computational time, the proposed algorithm has an advantage in terms of the speed-up increase per processor increase.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.19 no.2
• /
• pp.191-199
• /
• 1997

Mandibular trauma is developed due to traffic accident, fall down, industrial injury, and others. TMJ disorder is usually also developed after facial traumatic injury. Many authors suggested that disc displacement or tearing, acute synovitis, TMJ ankylosis, traumatic arthritis, or effusion are developed after facial trauma. It is still very controversible what is the best treatment of TMJ injury such as condylar fracture and meniscal injury. In TMJ injury, synovial inflammation is developed and pain mediators such as prostaglandin E2 or leukotriene B4 are released from the synovial membrane. This can be a cause of TMJ disorder. I present a variety of experimental study about the condylar fracture and meniscal injury and enzyme-immunoassay of synovial fluid after mandibular trauma that have been studied since 1992 and establish the treatment criteria of traumatic TMJ injury. I think that the treatment option of condylar fracture depends upon the surgeon's criteria exclusively. There are no significant differences between conservative and surgical treatment. If the aggressive functional physical therapy and long-term followup be performed, the favorable functional recovery of TMJ can be obtained. And I think that the initial surgical management of meniscus of TMJ is unnecessary in condylar fracture. And also arthrocentesis can be available to release the patient's subjective symptoms and improve the healing of injured TMJ.

• Journal of Industrial Technology
• /
• v.36
• /
• pp.39-43
• /
• 2016

The purpose of this study is to determine and compare the mechanical and flow properties of polyvinylsiloxane impression pastes. Twelve polyvinylsiloxane impression materials were used. As mechanical properties, tensile strength and tear resistance were measured. Impression materials are subjected to tensile stresses when they are removed from the oral cavity and from stone models and tear resistance is the ability of the material to resist tearing under a tensile stress. Flow is dependent on the ability of the material to resist shear forces. Flow tests were performed to determine the handling characteristics and was measured using a shark fin testing device. An impression material must be able to penetrate the narrow subgingival sulcus and tight interproximal areas. Therefore, it must be able to resist the shear forces as it is pushed between tooth and gingival walls. It is necessary to understand the properties of interocclusal recording materials and is considered that the results obtained in this study will provide guideline information for the manufacturing of impression materials and for selecting appropriate impression materials.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.45 no.3
• /
• pp.1-8
• /
• 2013

Hanji has been used mainly for preservation paper because of superior mechanical properties. However, it was not used in printing for inkjet and laser printer-printed letters. In this study, machine-made Hanji was prepared with five different contents of paper mulberry 20, 40, 60, 80 and 100% and managed by same pressure calendering. By increasing of paper mulberry contents, tearing index and folding endurance of machine-made Hanji increased because of increased fiber-to-fiber bonding. Printability property of machine-made Hanji improved by decreasing of paper mulberry contents. After 20 hours accelerated aging, the initial folding endurance of machine-made Hanji was reduced by approximately one-fourth degree. Between 40 and 100% contents of paper mulberry was showed similar levels about preservation property. The machine-made Hanji of paper mulberry 60% content was suitable for permanence and printability properties using preservation paper and printer-printed letters.

• Journal of the Korean Society of Physical Medicine
• /
• v.12 no.3
• /
• pp.11-21
• /
• 2017

PURPOSE: The purpose of this study is to identify the immediate effect of posterior pelvic tilt taping on anterior pelvic inclination, gait function, and balance in chronic stroke patients. METHODS: Fourteen chronic stroke subjects were enrolled in this study. Subjects who consented to participate in this cross-over experiment were assigned three interventions: posterior pelvic tilt taping, placebo taping, and no taping, in random order. After tape application, subjects were asked to complete: 1) Anterior pelvic tilt measurement, 2) 10-Meter Walk test, and 3) Limits of stability (LOS) test. To eliminate the learning effect of the tape after tearing off the tape, a 10 minute break was given between posterior pelvic tilt taping intervention and placebo taping intervention. RESULTS: Significant decreases were observed for the anterior pelvic inclination on both sides after posterior pelvic tilt taping application compared with placebo taping and no taping application (p<.05). Post hoc test results differed significantly in the 10-meter walk test after intervention (p<.05). However, there were no significant differences in limits of stability test after intervention (p>.05). CONCLUSION: Posterior pelvic tilt taping in chronic stroke patients decreases the inappropriate anterior pelvic inclination immediately and improves gait function, but it has little effect on balance.

• Journal of Ocean Engineering and Technology
• /
• v.29 no.1
• /
• pp.94-99
• /
• 2015

Lead zirconate titanate (PZT) thick films with thicknesses of ㎛ were fabricated on silicon substrates using an aerosol deposition method. A PZT powder solution was prepared using a sol-gel process. The average diameters (d50) obtained were 1.67, 1.98, and 2.40μm when the pyrolysis temperatures were 300℃, 350℃, and 450℃ respectively. The as-deposited film had a uniform microstructure without any cracks or pores. The as-deposited films on silicon were annealed at a temperature of 700℃. The 20-㎛-thick PZT film showed good adherence between the PZT film and substrate, with no tearing observed in the conventional solid phase process. This was probably because the presence of pores produced from organic residue during annealing relieved the residual stresses in the deposited film.