• Maxillofacial Plastic and Reconstructive Surgery
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• v.11 no.1
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• pp.32-40
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• 1989

This study is based on 247 patients(348 cases) with facial bone fracture who were admitted to the department of oral and maxillofacial surgery, Kangnam sacred heart Hospital during the period of Jan. 1983 through sep. 1988. The patients with mandible fracture were analysed with the following items such as complications with treatment method undertaken : Bicortical osteosynthesis vs Monocortical osteosynthesis, advantages and Disadvantages. The results obtained are as follows : 1) The most common age groups for the facial bone fracture were 20 years 2) The ratio of Men to women was 5 : 1 3) The most frequent location of facial bone fractures was the Mandible(76.7%), Maxillae(10.6%), Zygoma(9.5%), Nasal bone(3.2%) 4) The ratio of Mandible to Maxillae was 7.2 : 1 5) In mandible fractures, the most frequent fracture site was Symphysis(48.7%) 6) In maxilla fractures, the most frequent case was Le fort III fracture(51.4%), followed by Le fort I fracture(29.7%), Le fort II fracture(18.9%) 7) The main contributing causes of facial bone fractures were Traffic Accident(37.7%), Fight(31.6%), Accident(27.5%) 8) In open reduction methods of mandible fracture, the frequency of postop, malocclusion was 15% in interosseous wiring, 7% in Bicortical osteosynthesis, 3% in Monocortical osteosynthesis. The miniplates show advantages over other forms of fixation, in that they are malleable and easy to insert, they achieve rigid fixation and stability.

• Journal of Korean Foot and Ankle Society
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• v.16 no.2
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• pp.87-93
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• 2012

Fractures located at the metaphyseal/diaphyseal junction at the base of the fifth metatarsal were first described by Sir Robert Jones in 1902. However, ever since, there has been disagreement and debate regarding the diagnosis, classification, pathomechanics, the incidences, and potential causes of delayed unions and nonunions, and the optimal method of treatment. It appears to be widely agreed that proximal fractures of the metaphyseal/diaphyseal region of the fifth metatarsal are prone to delayed union or even nonunion. Several classifications of proximal fifth metatarsal stress fractures have been devised. Torg et al. classified fractures involving the proximal part of the diaphysis of the fifth metatarsal into three types. The Torg classification is a good grading system that can be used to determine the type of surgery needed as well as for the prediction of prognosis. The ''plantar gap'' might add to the decision-making process for surgery and improve the prediction of patient prognosis. In addition, the new classification using 'plantar gap' might be used for classification of fifth metatarsal stress fracture. Fifth metatarsal stress fractures can be treated conservatively or surgically, and excellent results have been reported for surgery with rapid recovery in athletes. Intramedullary screw fixation has become a popular form of fixation for fifth metatarsal stress fractures. Bone grafting presents the problems of a longer recovery time and additional skin incision for harvesting. The modified tension band wiring is an useful and simple option for surgical treatment of challenging fifth metatarsal stress fractures.

• Fire Science and Engineering
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• v.27 no.6
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• pp.89-96
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• 2013

The purpose of this study is to check the fire origin and cause of the fire by observing the shape of the flame propagation in air-conditioner indoor unit through the fire tests. We supposed that the flame is spread from the surroundings to the top of the air-conditioner and ignited on top of the air-conditioner with n-heptane. And then repeated this experiment twice under the same conditions. After the ignition, refrigerant filled in air-conditioner and lubricating oil exploded with large explosion and flame having high temperature and pressure belched out rapidly due to bursting refrigerant pipe linked air-conditioner between 734 seconds and 559 seconds. After result of checking the combustion residue we found that almost all of that was lost except a part of the evaporator, motor and metal. The position of short-circuit traces of wiring for the air-conditioner ignited itself is similar to that of fire damage by external flame. Therefore, we verified that it is not certain to determine the ignition cause and point by only the shape of the combustion residues.

• Korean Journal of Materials Research
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• v.20 no.11
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• pp.600-605
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• 2010

In order to meet the requirements of faster speed and higher packing density for devices in the field of semiconductor manufacturing, the development of Cu/Low k device material is explored for use in multi-layer interconnection. SiOC(-H) thin films containing alkylgroup are considered the most promising among all the other low k candidate materials for Cu interconnection, which materials are intended to replace conventional Al wiring. Their promising character is due to their thermal and mechanical properties, which are superior to those of organic materials such as porous $SiO_2$, SiOF, polyimides, and poly (arylene ether). SiOC(-H) thin films containing alkylgroup are generally prepared by PECVD method using trimethoxysilane as precursor. Nano voids in the film originating from the sterichindrance of alkylgroup lower the dielectric constant of the film. In this study, methyltriphenylsilane containing bulky substitute was prepared and characterized by using NMR, single-crystal X-ray, GC-MS, GPC, FT-IR and TGA analyses. Solid-state NMR is utilized to investigate the insoluble samples and the chemical shift of $^{29}Si$. X-ray single crystal results confirm that methyltriphenylsilane is composed of one Si molecule, three phenyl rings and one methyl molecule. When methyltriphenylsilane decomposes, it produces radicals such as phenyl, diphenyl, phenylsilane, diphenylsilane, triphenylsilane, etc. From the analytical data, methyltriphenylsilane was found to be very efficient as a CVD or PECVD precursor.

• Korean Journal of Materials Research
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• v.23 no.9
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• pp.483-488
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• 2013

Over the past few decades, high-nitrogen austenitic steels have steadily received greater attention since they provide a unique combination of high strength and ductility, good corrosion resistance, and non-magnetic properties. Recently, highnitrogen 18Mn-18Cr austenitic steels with enhanced strength have been developed and widely used for generator retaining rings in order to prevent the copper wiring from being displaced by the centrifugal forces occurring during high-speed rotation. The high-nitrogen austenitic steels for generator retaining ring should be expanded at room temperature and then stress relief annealed at around $400^{\circ}C$ to achieve the required mechanical properties. In this study, four kinds of high-nitrogen 18Mn-18Cr austenitic steels with different nitrogen content were fabricated by using a pressurized vacuum induction melting furnace, and then the effects of nitrogen content, cold working, and stress relieving on tensile properties were investigated. The yield and tensile strengths increased proportionally with increasing nitrogen content and cold working, and they further increased after stress relieving treatment. Based on these results, a semi-empirical equation was proposed to predict the tensile strength of highnitrogen 18Mn-18Cr austenitic steels for generator retaining rings. It will be a useful for the effective fabrication of high-nitrogen 18Mn-18Cr austenitic steels for generator retaining rings with the required tensile properties.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.6
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• pp.560-565
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• 2005

This paper deals with the development of manually operated die used for the manufacture of octagonal boxes into two sets of automated die. In particular, theoctagonal boxes are used fur the switch boxes intended fur the cable conduit of buildings or f3r wiring connection. Manufacturing these boxes requires forming the materials using the primary press before they undergo 2nd through 6th processing by the press machine including the four sides of the octagonal outlet box and bending. Such complicated process hikes up labor cost, slows down production, and results in defect rate of $10\%$ or higher; hence the overall rise in manufacturing cost. Moreover, workers avoid this type of work due to the roar and vibration coming from the press and the risk of accident. To eliminate such phenomenon, a CAM die made by integrating five sets of die into one set of die and an automatic conveyor system were developed. As a result, unmanned work was realized with only two units of press and two sets of die; thus solving the problem of work being avoided and saving on manufacturing cost.

• Journal of Korean Neurosurgical Society
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• v.49 no.6
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• pp.351-354
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• 2011

Objective : This investigation was conducted to evaluate a new, safe entry point for the C2 pedicle screw, determined using the anatomical landmarks of the C2 lateral mass, the lamina, and the isthmus of the pars interarticularis. Methods : Fifteen patients underwent bilateral C1 lateral mass-C2 pedicle screw fixation, combined with posterior wiring. The C2 pedicle screw was inserted at the entry point determined using the following method : 4 mm lateral to and 4 mm inferior to the transitional point (from the superior end line of the lamina to the isthmus of the pars interarticularis). After a small hole was made with a high-speed drill, the taper was inserted with a 30 degree convergence in the cephalad direction. Other surgical procedures were performed according to Harm's description. Preoperatively, careful evaluation was performed with a cervical X-ray for C1-C2 alignment, magnetic resonance imaging for spinal cord and ligamentous structures, and a contrast-enhanced 3-dimensional computed tomogram (3-D CT) for bony anatomy and the course of the vertebral artery. A 3-D CT was checked postoperatively to evaluate screw placement Results : Bone fusion was achieved in all 15 patients (100%) without screw violation into the spinal canal, vertebral artery injury, or hardware failure. Occipital neuralgia developed in one patient, but this subsided after a C2 ganglion block. Conclusion : C2 transpedicular screw fixation can be easily and safely performed using the entry point of the present study. However, careful preoperative radiographic evaluation, regardless of methods, is mandatory.

• Journal of Korean Neurosurgical Society
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• v.37 no.3
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• pp.201-206
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• 2005

Objective: To evaluate the accuracy and safety of C1-C2 transarticular screw insertion, we retrospectively review surgical records and postoperative radiological findings. Methods: From January 2001 to October 2003, the C1-C2 transarticular screw fixation and posterior wiring with iliac bone grafts was performed in 16 patients. 6 patients had rheumatoid arthritis which caused cervical instability, 3 patients had os odontoideum, 3 patients had type 2 odontoid process fracture, 3 patients had traumatic transverse ligament injury and 1 patients who had been managed with C1-C2 wire fixation had psoriatic arthritis. Results: Osseous fusion was documented in 15 patients(93.8%). Only one patient was recorded screw loosening because of postoperative infection. One patient had only one screw placed because of abnormal anatomical structure, one patients was breakage of a Kirschner wire, and one screw was medial location to lateral mass of C1, but clinical results was excellent and radiological instability was not noted. Conclusion: The author's experience demonstrates that C1-C2 transarticular screw fixation with wired bone graft is a safe procedure with higher fusion rate but precaution is needed to avoid the neural damage, vertebral artery injury, and hardware failure.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.3
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• pp.431-436
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• 2009

As the telecommunication lines bring into widespread use, one of the most important aspects related to power distribution systems is effectively to evaluate the effect on the telecommunication lines from power lines. One of the efficient methods to evaluate the effect is to measure the induced voltage of a telecommunication line as a result of a ground-loop. If the power lines cause high induced voltage, the ground reference in the telecommunication lines is no longer a stable potential, so signals may ride on the noise. A ground loop is common wiring conditions where a ground current may take more than one path to return to the grounding electrode at the arrangement between the power lines and telecommunication lines. When a multi-path connection between the power lines and telecommunication line circuits exists, the resulting arrangement is known as a ground loop. Whenever a ground loop exists, there are potential for damages or abnormal operations of the telecommunication lines. The power lines can induce the voltage on the communication line. The effects can be calculated by considering the inductances and capacitances. However, if we assume that there are only power lines, it doesn't have a practical meaning because there are conductors with other purpose in the neighborhood of the lines. If we consider that case, we need more complex system. Therefore we suggest more complex system considering the conductors with other purpose in the neighborhood of the lines. The neutral wires and the overhead ground wires are considered for calculating the induced voltage. We assume that there are the messenger wires beside the power line as a result of increased use of them. The main purpose of this paper is a study on a shielding effect of messenger wires in the distribution lines. EMTP(Electro-Magnetic Transients Program) program is used for the induced voltage calculation.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.15-20
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• 2017

This study presented the strength of the materials and parts for smart distribution board fabrication, and developed a work operation process chart for smart distribution board fabrication. This work operation process chart for smart distribution board fabrication complied with SPS-KEMC regulations, and the applicable range and object are less than 1,000 V and 1,000 Hz for the AC distribution board and less than 1,500 V for the DC distribution board. The power supply is 3 phase 4 wires ($3{\Phi}$ 4W), divided into a single phase circuit and a 3 phase circuit. In addition, the circuit was configured so that the leakage current flowing through the distribution line of the load could be monitored in real time by using the sensor module installed at the rear end of the circuit breaker. Therefore, the administrator can easily find the risk factor of the load since engineer can check the leakage current of each distribution line. In addition, if a leakage current greater than standard value flows, it is possible to generate an alarm against a short circuit and cut off the leakage current. The work operation process chart for the smart distribution board fabrication consists of the following steps: raw and subsidiary materials, sheet metal work, tube making, welding, painting, busbar fabrication, assembly and wiring, product inspection, shipment, etc. Moreover, symbols, ${\Delta}$, ${\nabla}$, ${\bigcirc}$, ${\Rightarrow}$, etc. were used according to the type of work and work progress so that workers can easily understand the progress of the work.