• Restorative Dentistry and Endodontics
• /
• 제15권2호
• /
• pp.17-33
• /
• 1990

The purpose of this study was to evaluate the fracture toughness of dental composite resins and to investigate the filler factor affecting the fracture behaviour on which the degree of fracture toughness depends. Six kinds of commercially available composite resin;, including two of each macrofilled, microfilled, and hybrid type were used for this study, The plane strain fracture toughness ($K_{10}$) was determined by three-point bending test using the single edge notch specimen according to the ASTM-E399. The specimens were fabricated with visible light curing or self curing of each composite resin previously inserted into a metal mold, and three-point bending test was conducted with cross-head speed of 0.1mm/min following a day's storage of the specimens in $37^{\circ}C$ distilled water. The filler volume fractions were determined by the standard ashing test according to the ISO-4049. Acoustic Emission(AE), a nondestructive testing method detecting the elastic wave released from the localized sources In material under a certain stress, was detected during three-point bending test and its analyzed data was compared with, canning electron fractographs of each specimen. The results were as follows : 1. The filler content of composite resin material was found to be highest in the hybrid type followed by the macrofilled type, and the microfilled type. 2. It was found that the value of plane strain fracture toughness of composite resin material was in the range from 0.69 MPa$\sqrt{m}$ to 1 46 MPa$\sqrt{m}$ and highest In the macrofilled type followed by the hybrid type, and the microfilled type. 3. The consequence of Acoustic Emission analysis revealed that the plane strain fracture toughness increased according as the count of Acoustic Emission events increased. 4. The higher the plane strain fracture toughness became, the higher degree of surface roughness and irregularity the fractographs demonstrated.

• 대한핵의학회지
• /
• 제23권2호
• /
• pp.215-218
• /
• 1989

Tc-99m-tin colloid distribution in the hip is studied in 76 patients with no hepatic and hip disorder, because knowledge of normal uptake pattern in the hip is important in evaluation of femoral head vasculature after a fracture. The uptake in femoral head is decreased or disappeared with increasing age due to conversion of red marrow to white marrow.

• Journal of Audiology & Otology
• /
• 제25권4호
• /
• pp.230-234
• /
• 2021

Otosclerosis, a hereditary disorder characterized by disordered resorption and deposition of bone, results in progressive hearing loss. Osteogenesis imperfecta (OI) is a genetic disorder characterized by recurrent fractures, blue sclera, and varying degrees of hearing impairment; and is a known risk factor for otosclerosis. After adolescence, the risk of fracture decreases, reducing the need for follow-up in OI. However, otosclerosis is a progressive disorder. In this report, we discuss two cases of familial otosclerosis with different clinical features. We hypothesize that the difference in hearing level correlates with the difference in computed tomography findings. The mother, whose case was considered severe, was prescribed hearing aids, while the daughter, who had normal hearing level, was regularly followed up.

• 대한청각학회지
• /
• 제25권4호
• /
• pp.230-234
• /
• 2021

Otosclerosis, a hereditary disorder characterized by disordered resorption and deposition of bone, results in progressive hearing loss. Osteogenesis imperfecta (OI) is a genetic disorder characterized by recurrent fractures, blue sclera, and varying degrees of hearing impairment; and is a known risk factor for otosclerosis. After adolescence, the risk of fracture decreases, reducing the need for follow-up in OI. However, otosclerosis is a progressive disorder. In this report, we discuss two cases of familial otosclerosis with different clinical features. We hypothesize that the difference in hearing level correlates with the difference in computed tomography findings. The mother, whose case was considered severe, was prescribed hearing aids, while the daughter, who had normal hearing level, was regularly followed up.

• Journal of Trauma and Injury
• /
• 제36권3호
• /
• pp.261-264
• /
• 2023

Pancreatic trauma occurs in 0.2% of patients with blunt trauma and 5% of severe abdominal injuries, which are associated with high mortality rates (up to 60%). Traumatic pancreatoduodenectomy (PD) has significant morbidity and appreciable mortality owing to complicating factors, associated injuries, and shock. The initial reconstruction in patients with severe pancreatic injuries aggravates their status by causing hypothermia, coagulopathy, and acidosis, which increase the risk for early mortality. A staging operation in which PD follows damage control surgery is a good option for hemodynamically unstable patients. We report the case of a patient who was treated by staging PD for an injured pancreatic head.

• Journal of Advanced Marine Engineering and Technology
• /
• 제29권7호
• /
• pp.801-807
• /
• 2005

Any failure of intake and exhaust valves of marine diesel engine must be regarded as serious, and any steps which can be taken to prevent such failure are desirable. The purposes of this study is to investigate and to analyse the failure causes of intake and exhaust valves for marine diesel engine during sea trial after completion of overhauling. In this study, to analyse the failure causes, we have carried out on board inspection, fractography test and discussion based on the specimen and repairing report provided by the ship owner. From the results of above inspection, test and discussion, it has been considered reasonable to conclude that the causes of damaged valves of the ship are as follow ; 1) During operation, the stick or seizure of valve spindle occurred and hence the movement of exhaust valve spindle was to be resisted and subsequently the engine was to be operated under an unappropriated valve timing and the exhaust valve sustained the repeated loads exceeding the fatigue strength of valve material. 2) By the loads above described, the fatigue fracture was initiated at the structural noncontinuous part of exhaust valve spindle, and then the valve head was finally fractured and dropped in the cylinder. 3) The fractured exhaust valve head impacted the intake valve at various direction to be bent or damaged.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.1039-1044
• /
• 2003

Adhesive-bonded joints are widely used in the industry. Recently aircraft applications of adhesive bonding joints have been increased extensively in automobile and air industry. Because adhesives which are available for structural applications have been developed a lot and understanding of adhesive bonding has been improved so much. In this study, as the fundamental research of design of adhesive bonding joints, this study considers specimen shape are affect strength and durability of Al/Polymer lap joints. In this research, cross head speed difference were concerned to evaluate their effects on the adhesive strength. Cross head speed makes a change 0.05mm/min, 0.5mm/min, 5mm/min. The result is load-displacement diagram showed brittleness fracture tendency. Fracture tendency that is shown enough on stress distribution of trigonal single lap joint and trigonal edged single lap joint occur the inside of adhesive.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제34권3호
• /
• pp.388-397
• /
• 2008

The present study was performed to evaluate the function of the mandible according to the pattern of fracture and treatment methods of condylar fractures of the mandible and help operators in making a treatment plan. Sixty patients (average follow-up period was $7.8{\pm}9.4$ months) who were treated for condylar fracture from June, 2002 to May, 2006 at the Department of Oral and Maxillofacial surgery, Chonnam National University Hospital were reviewed. The common causes of the condylar fracture were traffic accident and fall-down (35.0%). In concomitant injuries, laceration was 46.7% and the fracture of the mandibular symphysis was highest incidence (60.0%). The common site of the fracture was the condylar head (47.8%), followed by subcondyle (36.2%) and condylar neck (15.9%). Under 15 years old patients, the closed reduction was performed in 87.5% out of the patients. All of the condylar fragments were fixed to the mandible with titanium miniplates in cases of open reduction. The mean period of intermaxillary fixation (IMF) was $14.2{\pm}6.5$ days in closed reduction and $10.0{\pm}4.2$ days in open reduction. The old patient with bilateral condylar head fractures, who were treated by closed reduction with IMF for 3 weeks, showed the limitation of mandibular movements. But, there was no significant different results between open reduction and closed reduction with the respect of the Helkimo's mandibular mobility index and clinical dysfunction index (DI). Complications, such as fibrous ankylosis and resorption of the mandibular condyle, were not observed in all patients. These results suggest that the good results can be obtained by closed reduction with proper IMF periods and functional exercise in most condylar fractures of the mandible except severely displaced extracapsular fractures.

• Journal of Trauma and Injury
• /
• 제22권2호
• /
• pp.123-127
• /
• 2009

Purpose: There is an increasing amount of evidence that S100B could function as a marker of brain damage. However, the cerebral specificity of S100B has been questioned, so the extracerebral sources of S100B have been paid attention. We performed this investigation to show serum S100B levels after extracranial fracture in patients without current head injury and without prior neurological disease. Methods: At the emergency department, we obtained the blood samples within 6 hours from trauma patients hospitalized with extracranial fractures. S100B levels were compared between one fracture and more than two fractures, and analyzed according to the presence of soft tissue damage. Results: Patients with one fracture and those with more than two fractures did not differ by age (mean, 54.70 vs. 47.03, p=0.130), and there was no significant difference in the male-to-female ratio(33:32 vs. 21:12, p=0.226). In patients with one fracture, the mean value of S-100B was $0.56{\mu}g/L$ (95% CI: 0.35-0.77) whereas in those with more than two fractures, the corresponding value was $1.09{\mu}g/L$ (95% CI: 0.46-1.7, p=0.048). The S100B level of patients with soft tissue damage($1.32{\pm}0.38$) was higher than that of patients without soft tissue damage($0.81{\pm}0.21$), whether one fracture or more than two fractures(p=0.049). Conclusion: We present here that S100B levels were raised in 77% of patients with extracranial fractures without cerebral injury who were hospitalized from the emergency room and that the presence of soft tissue damage contributed to the increased S100B rather than the size of the fractured bone size or the number of fracturest. Thus, this study suggests that soft tissue injury may be considered as an important extracerebral source of S100B.

• Clinics in Shoulder and Elbow
• /
• 제9권2호
• /
• pp.231-234
• /
• 2006

We experienced a case of impingement caused by a bone fragment which was impacted between acromion and humeral head in a child. The bone fragment came from antero-inferior glenoid fracture. Satisfactory clinical results and stability were obtained by arthroscopic bone fragment removal. In case that bone fragment is located in the upper shoulder joint and results in impingement, We must consider not only greater tubercle fracture but also glenoid fracture. Magnetic resonance imaging can assist in the preoperative diagnosis.