• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.29 no.6
• /
• pp.329-337
• /
• 2019

We synthesized potassium titanates having splinter and plate shape and evaluated frictional and wear properties of brake pad using them as reinforcements in friction materials. For splinter-shaped potassium titanates, potassium tetratitanate (K₂O·4TiO₂, PT4) with plate shape was prepared, then K ion of the titanate was leached by acid to make potassium hexatitanate (K₂O·6TiO₂, PT6), which was transformed to splinter-shaped PT6 by thermal treatment at 800℃. Plate-shaped potassium magnesium titanate (K_0.8Mg_0.4Ti_1.6O₄, PMT) was prepared by adding Mg in the potassium titanate using KCl as a flux. Using PT6 and PMT as reinforcements in friction materials of brake pad, we evaluated frictional and wear properties using 1/5-scale dynamometer. According to dynamometer test results, both reinforcements shows similar friction coefficient and fade & recovery behavior to conventional material and plate-shaped PMT exhibits higher wear resistance than splinter-shaped PT6.

• Korean Journal of Materials Research
• /
• v.27 no.3
• /
• pp.132-136
• /
• 2017

We synthesized potassium hexatitanate, ($K_2Ti_6O_{13}$, PT6), with a non-fibrous shape, by acid leaching and subsequent thermal treatment of potassium tetratitanate ($K_2Ti_4O_9$, PT4), with layered crystal structure. By controlling nucleation and growth of PT4 crystals, we obtained splinter-type crystals of PT6 with increased width and reduced thickness. The optimal holding temperature for the layered PT4 was found to be ${\sim}920^{\circ}C$. The length and width of the PT4 crystals were increased when the nucleation and growth time were increased. After a proton exchange reaction using aqueous 0.3 M HCl solution, and subsequent heat treatment at $850^{\circ}C$, the PT4 crystal transformed into splinter-type PT6 crystals. The frictional characteristics of the friction materials show that as the particle size of PT6 increases, the coefficient of friction (COF) and wear amounts of both the friction materials and counter disc increase.

• International Journal of Precision Engineering and Manufacturing
• /
• v.4 no.1
• /
• pp.30-36
• /
• 2003

Brittle materials such as glasses and ceramics, which are very weak under impact loading, show fragile failure mode due to their low fracture toughness and crack sensitivity. When brittle materials are subjected to impact by small spheres, high contact pressure occurs at the impacted surface causing local damage on the specimen. This damage is a dangerous factor in causing the final fracture of structures. In this research, the crack propagation process of soda-lime glass by the impact of small spheres is explained and the effects of several constraint conditions for impact damage were studied by using soda-lime glass; that is, the effects for the materials and sizes of impact ball, thickness of specimen and residual strength were evaluated. Especially, this research has focused on the damage behavior of ring cracks, cone cracks and several other kinds of cracks.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.1
• /
• pp.153-159
• /
• 2002

Brittle materials such as ceramics and glasses show fragile fracture due to the low toughness and the crack sensitivity. When brittle materials are subjected to impact loading by small spheres, high contact pressure occurs to the surface of the specimen. Local damage is subsequently generated in the specimen. This local damage is a dangerous factor which gives rise to the final fracture of structures. In this research, impact damage of soda-lime glass plates by small spheres was evaluated by considering the effects of impact directions of indenter, pressure condition of specimen and residual strength after impact loading.

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.11
• /
• pp.93-100
• /
• 2001

Brittle materials are very weak for impact because of typical characteristics which happen to be easily fractured with low fracture toughness and crack sensitivity. When brittle materials are subjected to impact due to small spheres, high contact pressure is occurred to impact surface and then local damage on specimen is developed, since there are little plastic deformations due to contact pressure compared to metals. This local damage is a dangerous factor which gives rise to final fracture of structures. In this research, the crack propagation process of soda lime glass by impact of small sphere is explained and the effects of the constraint conditions of impact spheres and materials for the material damage were studied by using soda-lime glass. that is the effects for the materials and sizes of impact ball, thickness of specimen and residual strength. Especially, this research has focused on the damage behavior of ring crack, cone crack and several kinds of cracks.

• Journal of Chest Surgery
• /
• v.49 no.5
• /
• pp.408-412
• /
• 2016

A 50-year-old female patient with visual disturbances was referred for further evaluation of a heart murmur. Fundoscopy revealed a Roth spot in both eyes. A physical examination showed peripheral signs of infective endocarditis, including Osler nodes, Janeway lesions, and splinter hemorrhages. Our preoperative diagnosis was subacute bacterial endocarditis with severe aortic regurgitation. The patient underwent aortic valve replacement and was treated with intravenous antibiotics for 6 weeks postoperatively. The patient made a remarkable recovery and was discharged without complications. We report this case of subacute endocarditis with all 4 classic peripheral signs in a patient who presented with visual disturbance.

• PNF and Movement
• /
• v.16 no.2
• /
• pp.195-205
• /
• 2018

Purpose: The purpose of this study was to demonstrate the effects of proprioceptive neuromuscular facilitation (PNF) stability techniques on walking speed, trunk stability, and balance in stroke patients. Methods: Ten stroke patients volunteered to participate in the study, and each of subjects was randomly assigned to either the stability technique (ST) group (n=5) or to the treadmill (TM) group (n=5). Each therapeutic exercise program was provided for 30 minutes a day, 5 days per week for 4 weeks. The ST group performed a PNF pattern combined with stabilizing reversal and rhythmic stabilization of the PNF stability technique. Walking speed (measured using a 10-meter walking test), trunk stability (TIS), and balance (BBS, FRT) were evaluated before and after training. All data were analyzed using SPSS version 18.0. The significance level for statistical inspection was set at 0.05. Results: Both groups showed improvements on the 10-meter walking test, the trunk impairment scale, the Berg balance scale, and the functional reaching test. Conclusion: PNF stability techniques are effective for improving trunk stability, balance, and walking speed in stroke patients. For stroke patients, PNF stability techniques are very useful and effective, including in clinical practice.

• Cartoon and Animation Studies
• /
• s.31
• /
• pp.249-266
• /
• 2013

The purpose of this research is to study a case of the minimalism on Game Graphic User Interface design in Computer game. It is to analyse the minimal tendency on Game Graphic User Interface design in several Computer games such as Prince of Persia, Mirror's Edge, Splinter Cell, Gears of War, Call of Duty4, Metro 2033, Crysis2. These games expanded the field of Game Graphic User Interface design with the unique form of minimalism. Minimalism came from the formative arts in the 1960s and influenced to other fields of art. It seems to be an expression of various styles that promptly meet the needs of the times. Therefore, in this research, I would highlight the phenomenon of minimalisation in Game Graphic User Interface design and research the influence of Minimalism that appears in modern design focused on "simplicity" and "minimum" which are representative trend of Minimalism.

• Tuberculosis and Respiratory Diseases
• /
• v.43 no.2
• /
• pp.236-242
• /
• 1996

Intracranial tuberculoma results from hematogenous spread of pulmonary, intestinal or urogenital tuberculosis. However, it might be caused by pulmonary tuberculosis, mainly. Clinically, symptoms of intracranial tuberculoma are headache and seizure, its symptoms are simillar to intracranial tumor. A 25-year-old-unmarried shopgirl was visited to this hospital because of headache, dizziness and visual disturbance for couple weeks in Sep. 1995. She had been treated with anti-tuberculosis agents of miliary tuberculosis during past nine months period. Brain MRI revealed intracranial tuberculoma and brain edema but not involved optic nerve. Ophthalmic examination revealed severe papilledema and splinter hemorrhage with bitemporal hemianopsis and central scotoma. This finding was strongly suggested of optic disc tuberculoma. Her symptoms became much better following repeated retrobulbar steroid injection with continuous anti-tuberculosis agents. We report a interesting case with intracranial tuberculoma and optic disc tuberculoma associated by miliary tuberculosis during anti-tuberculous treatment.