• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1925-1928
• /
• 2005

In recent years, the importance of the characterization of fall for a fracture prevention system keeps increasing since fracture from a fall can lead to serious health problems. Fall is one of the major sources which increase morbidity in elderly people. In terms of the cost and the influence to the quality of life, the most serious injury with hip fractures is caused by falls. The traditional methods in characterizing fall patterns have been mainly by the epidemiological surveys. With surveys, the exact data of fall patterns can not been acquired. In this paper, we measured and analyzed with the parameters related to fall pattern such as velocities and accelerations during the motion of falls using 3D motion capture program. We acquired the parameters of the fall pattern of intentional and unexpected fall. The result showed that the variation of velocity and acceleration during fall was very important in characterizing fall pattern, which of vital importance for the development of a fracture prevention system and for the safety of the elderly

• The Journal of Korean Academy of Prosthodontics
• /
• v.39 no.1
• /
• pp.14-24
• /
• 2001

The purpose of this study was to compare the fracture strengths and the fracture patterns of several hybrid-ceramic crowns and metal-ceramic crown. Ten crowns were constructed for each group according to the manufacturer's instruction. Removable template of silicone rubber impression material was used for standardization of each crowns. Each crown was cemented on a metal die with hybrid glass ionomer cement. All crowns cemented were stored in distilled water, $36^{\circ}C$ for 24 hours prior to loading in an universal testing machine. The load was directed at 130 degrees the long axis of metal die. The fracture strengths were measured and the fracture patterns were observed. The following results were obtained from this study 1. The mean fracture strengths of $Artglass^{(R)}$, $Sculpture^{(R)}$ and $Targis^{(R)}$ were $57.5{\pm}9.5Kgf,\;62.7{\pm}12.2Kgf$ and $60.2{\pm}10.1Kgf$ respectively. There was no significant difference among each hybrid ceramic crown group. 2. The toad required to fracture hybrid-ceramic crowns was significantly smaller than metal-ceramic crowns($131.7{\pm}22.0Kgf$). 3. In the metal-ceramic crowns, labial porcelain detached partially from porcelain-metal junction of proximal side by load. 4. Hybrid-ceramic crowns showed a simple fracture pattern that fracture line began at the loading area and extended through proximal surface, perpendicular to the margin. The crown was separated into two parts of labial side and lingual side. Above results revealed that three kinds of the hybrid-ceramic crowns used in this study must have careful application in clinical use since the strength of hybrid-ceramic crown was lower(about 1/2) than that of metal-ceramic crown.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.40
• /
• pp.29.1-29.11
• /
• 2018

Background: For proper recovery from craniofacial fracture, it is necessary to establish guidelines based on trends. This study aimed to analyze the patterns and causes of craniofacial fractures. Methods: This retrospective study analyzed patients who underwent surgery for craniofacial fractures between 2010 and 2017 at a single center. Several parameters, including time of injury, region and cause of fracture, alcohol intoxication, time from injury to surgery, hospitalization period, and postoperative complications, were evaluated. Results: This study analyzed 2708 fracture lesions of 2076 patients, among whom males aged 10 to 39 years were the most numerous. The number of patients was significantly higher in the middle of a month. The most common fractures were a nasal bone fracture. The most common causes of fracture were ground accidents and personal assault, which tended to frequently cause more nasal bone fracture than other fractures. Traffic accidents and high falls tended to cause zygomatic arch and maxillary wall fractures more frequently. Postoperative complications-observed in 126 patients-had a significant relationship with the end of a month, mandible or panfacial fracture, and traffic accidents. Conclusions: The present findings on long-term craniofacial fracture trends should be considered by clinicians dealing with fractures and could be useful for policy decisions.

• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.947-950
• /
• 1998

Geological structures such as fault and fracture patterns provide important information about preliminary exploration of mineralized areas and geological characterization. We apply a filtering method taking the sun's azimuth angle into account to a shaded relief image derived from a digital elevation model (DEM), by which even linear edges extending parallel to the sun direction can be effectively extracted. Then, Generalized Hough tranform is applied to extract lineanments which correspond to fault and fracture patterns.

• Proceedings of the KACD Conference
• /
• 2003.11a
• /
• pp.599-599
• /
• 2003

Endodontic rotary NiTi(Nickel-Titanium) files have several advantages, but they also have some problems. Fracture of instrument is the one of the problems. Cyclic fatigue fracture may not give a previous sign(ex, bending or distortion of the files) before it happen. It is affected by various factors. This study investigated time which takes for cyclic fatigue fracture to happen and fracture patterns with regard to different NiTi files and pecking motion.(omitted)

• The Korean Journal of Health Service Management
• /
• v.9 no.4
• /
• pp.131-144
• /
• 2015

Objectives : This study investigated the health care utilization patterns and length of stay (LOS) determinants of fracture patients with workers' compensation insurance (WCI) and national health insurance (NHI). Methods : The discharge summary data of 4,394 WCI fracture patients were compared to 28,874 NHI patients. Health care utilization characteristics were compared with a logistic regression analysis, and the LOS determinants were identified with linear regression analysis. Results : The average LOS of the WCI fracture patients was 2.4 times higher than that of the NHI patients. WCI patients used more small or medium sized hospitals, and were more frequently admitted through the emergency room. Females, older patients and patients admitted through emergency room had a significant positive impact on LOS. Conclusions : Healthcare utilization by the WCI fracture patients may include medically unnecessary hospital stays. Therefore, policy makers need to respond appropriately to the inefficient use of health resources by WCI patients.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.21 no.4
• /
• pp.366-369
• /
• 1999

The nasal and zygoma bone are parts of frequently fracturing of facial bones because of anatomically protrusion. Of facial bone fractures, nasal bone is at the high level of incidence rate. But zygoma fracture that anatomical characteristics increase the incidence rate also is occupied considerable part of the facial bone fracture. The outline of face is decided by form of underlying skeletal structure, of that, zygoma plays an important role in. Zygoma is closely attached to surrounding anatomic structure as orbit, maxillary sinus. Aesthetic and functional disturbance are developed by zygoma fracture from trauma, complications, as facial asymmetry, trismus, sensory disturbance, epistaxis, periorbital hemorrhage, diplopia etc, are developed. The patterns of complications following displacement of fractured fragment of zygoma by trauma are slightly different.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.44 no.6
• /
• pp.269-274
• /
• 2018

Objectives: The incidence and patterns of mandibular fractures vary by country and population age. This retrospective study evaluated the etiologies and patterns of mandibular fractures in children. Materials and Methods: The clinical records of 89 children (45 males and 44 females) aged 0 to 12 years who presented with mandibular fractures from July 2012 to June 2016 were retrospectively reviewed. The sex, patient age, site of fracture, etiology of trauma, and monthly variations of the fractures were recorded. Descriptive statistics, the z-test and chi-square test were used for statistical analysis and the P-value was set at <0.05. Results: Eighty-nine children (male-to-female ratio 1.02:1) sustained 131 mandibular fractures. Within the study sample, the 6 to 9 year age group most frequently experienced fractures (47.3%). Falls and road traffic accidents (RTA) were the two most common etiological factors that accounted for 44.9% and 24.7% of cases. The condylar fracture was the most common anatomical location (38.9%) followed by the angle (20.6%), parasymphysis (18.3%), body (15.3%), and symphysis (5.3%). A single fracture (51.7%) was more common than multiple fractures (48.3%). The month-wise distribution of mandibular fractures was fairly constant. Conclusion: The condylar region was the most common anatomic site for fractures; in addition, a fall and RTA were the major etiological factors for mandibular fractures. A single fracture was observed in 51.7% of patients while multiple fracture lines accounted for 48.3% of cases.

• Advances in concrete construction
• /
• v.13 no.1
• /
• pp.83-99
• /
• 2022

The two, NBD and SCB tests using gypsum circular discs each containing a single notch have been experimentally accomplished in a rock mechanics laboratory. These specimens have also been numerically modelled by a two-dimensional particle flow which is based on Discrete Element Method (DEM). Each testing specimen had a thickness of 5 cm with 10 cm in diameter. The specimens' lengths varied as 2, 3, and 4 cm; and the specimens' notch angles varied as 0°, 45° and 90°. Similar semi-circular gypsum specimens were also prepared each contained one edge notch with angles 0° or 45°. The uniaxial testing machine was used to perform the experimental tests for both NBD and SCB gypsum specimens. At the same time, the numerical simulation of these tests were performed by PFC2D. The experimental results showed that the failure mechanism of rocks is mainly affected by the orientations of joints with respect to the loading directions. The failure mechanism and fracturing patterns of the gypsum specimens are directly related to the final failure loading. It has been shown that the number of induced tensile cracks showing the specimens' tensile behavior, and increases by decreasing the length and angle of joints. It should be noted that the fracture toughness of rocks' specimens obtained by NBD tests was higher than that of the SCB tests. The fracture toughness of rocks usually increases with the increasing of joints' angles but increasing the joints' lengths do not change the fracture toughness. The numerical solutions and the experimental results for both NDB and SCB tests give nearly similar fracture patterns during the loading process.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.05a
• /
• pp.333-338
• /
• 2001

Fractal geometry is a non-Euclidean geometry which has been developed to quantitative analysis irregular or fractional shapes. Fractal dimension of irregular surface has fractal values ranging from 2 to 3 and of irregular line profile has fractal values ranging from 1 to 2. In this paper, quantitative analysis of crack growth patterns during the fracture processing of fiber-reinforced cement composites based on fractal geometry. The fracture behaviors of fiber reinforced mortar beams subjected to three-point loading in flexure. The beams all had a single notch depth, but varing volume fractions of polypropylene, cellulose fibers. The crack growth behaviors, as observed through the image processing system, and the box counting method was used to determine the fractal dimension, Df. The results showed that the linear correlation exists between fractal dimension and fracture energy of the fiber reinforced cement mortar.