• Journal of Technologic Dentistry
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• v.24 no.1
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• pp.127-138
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• 2002

There are some cases that dental prosthesis does not operate as properly as expected in oral mouth. The reasons are such as a distortion of the mandibular, a fault of impression taking system or an extrusion of remaining teeth. One of dental prostheses to consider in the situations is the attachment which connects segment bridge. Active discussions are managed on theoretical side of this field but few on clinical side of it, which must be considered first. Accordingly I'd like to suggest a theoretical background for connect attachment of fixed segmented bridge. 1. As a bridge gets longer, burden on dental ligament is increased and the hardness of a bridge is lessened. 2. The flexibility of a bridge increases in ratio to 3 multiplication of the length and decreases in ratio to 3 multiplication of the width of occlusal surface and base of pontic. 3. Precision rest is needed to cope with the shake of teeth and the difference of axis direction among abutments. 4. Female part of the precision rest should be on middle abutment distal and male one on mesial of pontic. 5. Segmented attachment can be efficiently used to cope with long span bridgework and also in case that one piece casting can't be done because of slant of abutment.

• Steel and Composite Structures
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• v.35 no.3
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• pp.371-384
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• 2020

The steel-concrete double composite girder in the negative flexural region combines an additional concrete slab to the steel bottom flange to prevent the local steel buckling, however, the additional concrete slab may lower down the neutral axis of the composite section, which is a sensitive factor to the tensile stress restraint on the concrete deck. This is actually of great importance to the structural rationality and durability, but has not been investigated in detail yet. In this case, a series of 5.5 m-long composite girder specimens were tested by negative bending, among which the bottom slab configuration and the longitudinal reinforcement ratio in the concrete deck were the parameters. Furthermore, an analytical study concerning about the influence of bottom concrete slab thickness on the cracking and sectional bending-carrying capacity were carried out. The test results showed that the additional concrete at the bottom improved the composite sectional bending stiffness and bending-carrying capacity, whereas its effect on the concrete crack distribution was not obvious. According to the analytical study, the additional concrete slab at the bottom with an equivalent thickness to the concrete deck slab may provide the best contributions to the improvements of crack initiation bending moment and the sectional bending-carrying capacity. This can be applied for the design practice.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.24 no.2
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• pp.227-236
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• 1994

The purpose of this study was to observe mandibular condyle shape in an asymptomatic population. In order to carry out this study, 96 temporomandibular joints in 48 adults(22 males, 26 females), who were asymptomatic for temporomandibular disturbances and had no history of prosthodontic or orthodontic treatments, were selected, and radiographed using the Sectograph(Denar Co., U.S.A.) for lateral and frontal individualized corrected TMJ tomograph and submentovertex radiograph. Mandibular condyles were classified morphologically, and measured medioateral and anteroposterior dimensions and condylar angulation. The obtained results were as follows. 1. In the classification of condyle shape on lateral tomographs, 94.8% were convex type and 5.2% were angled type. 2. In the classification of condyle shape on frontal tomographs, 45.3% were convex type, 32.0% were round type, 16.0% were flat type, and 6.7% were angled type. 3. In the classification of condyle shape on submentovertex radiographs, 34.5% were flat-convex type, 22.9% were flat-flat type, 20.8% were concave-convex type, 19.8% were convex-convex type, and 1.0% were concave-flat type and convex-flat type. Concave-concave type, convex-concave type, and flat-concave type were not observed. 4. The average mediolateral legth of the condyle was 19.3㎜ and the average anteroposterior length was 9.4㎜. The average angle between the long axis of condyle and the coronal plane made on submentovertex view was 19.6 degrees.

• Journal of Korea Multimedia Society
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• v.23 no.2
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• pp.282-292
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• 2020

In order to minimize casualties from marine vessel accidents that occur frequently at home and abroad, it is important to ensure the safety of the passengers aboard the vessel in the event of an accident. There is an EPIRB system as a system for disaster preparedness in the marine situation currently on the market, but there is a problem that the price is very expensive. In order to overcome the cost problem, which is a disadvantage of previous system, LoRaWAN-based communication is used. LoRaWAN communication-based vessel positioning and risk detection system based on LoRaWAN communication transmits measurement data of each module using two Beacon and GPS modules to stably perform position measurement for both indoor and outdoor situations. The rider danger situation detection system can detect the safety status of the rider using the 3-axis acceleration sensor, collect data from the rider positioning system and the rider safety status detection system, and send to server using LoRa communication. When conducting communication experiments in the long-distance maritime situation and actual communication experiments using the implemented system, it was found that the two experiments showed over 90% communication success rate on average.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.12
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• pp.1635-1646
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• 1997

The nozzle length to diameter ratio of real diesel nozzles is about 2-8 which is not long enough for a fully developed and stabilized flow. The characteristics of the flow such as turbulence at the nozzle exit which affect the development of the spray can be enhanced by impinging the flow inside nozzle. The flow details inside the impinging nozzles have been investigated both experimentally and numerically. The mean velocities, the fluctuating velocities, and discharge coefficients in the impinging inlet nozzles, round inlet nozzle, and sharp inlet nozzle were obtained at various Reynolds number. The developing feature of the external spray were photographed by still camera and the droplet sizes and velocities were also measured by laser Doppler technique. The spray angle was greater and the droplet sizes near the spray axis were smaller with the impinging flow inside nozzle.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.296-305
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• 2012

In this paper, we develop about glare phenomenon at security light caused by light source's straight characteristic, maintaining uniformity ratio of illuminance as high, have long light distribution not by symmetry of rotation but a single axis. we develop second lens for security light that lack of light distribution phenomenon at each of security light can be solved. Our developed light system design satisfies lighting standard of security light's and shape of lens is single lens. so our lens optimizes designing or analysis by using lighting design and interpretation program. Making a Mock-up to do real measure, we have intensity of illumination and maintaining uniformity ratio of illuminance measurement data.

• Journal of Korean Foot and Ankle Society
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• v.7 no.1
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• pp.61-67
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• 2003

Purpose: We evaluate the clinical, radiologic and pathologic features of giant cell tumor of tendon sheath (GCTTS) in the foot Materials and Methods: Twelve cases of GCTTS excised from foot region, at our hospital from 1999 to 2002, were analyzed. The mean duration of follow up was 19 months. The age and sex of the patient, location and size of the lesion, symptom as well as radiologic findings were evaluated. Results: The most common symptom was painless mass in 7 patients. Three patients had pain sympton and 2 patients had tenderness. The mean duration from identification of the mass to excision was 14 months. Seven cases were located in the forefoot, most commonly in the big toe with 4 cases, 2 cases in the midfoot and 3 cases in the hindfoot. The average diameter along the long axis was 2.8cm. Conclusion: GCTTS in the foot was more common in the big toe and also plantar side same as in the hand. But bony erosion and pain were more frequent than in the hand.

• The Journal of Korean Physical Therapy
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• v.21 no.4
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• pp.97-102
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• 2009

Purpose: The purpose of this study was to investigate the effects of low intensity pulsed ultrasound on TGF-$\beta$1 expression and healing of rat femur penetrating fractures. Methods: Rats were anesthetized with ketamine and xylazine. Using aseptic technique, we exposed the lateral right femoral diaphysis with removal of the periosteum. We made one hole along its long axis with an electrically-driven 1.8 mm diameter drill bit. Postoperatively, rats were divided into two groups (a control group, n=15; an experimental group, n=15). The experimental group was treated with low intensity pulsed ultrasound (pulse rate: 1:4, 0.5 W/$cm^2$, 10 minutes, 1 time per day) for 3 weeks. The control group was treated with sham ultrasound (with the US unit turned off). Results: The experimental group achieved more callus formation and TGF-$\beta$1 expression than the control group at the $7^{th}$, $14^{th}$ and $21^{st}$ days after low intensity pulsed ultrasound treatment. Conclusion: This study suggests that low intensity pulsed ultrasound facilitates bone fracture repair, possibly via increased TGF-$\beta$1 expression.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.189-190
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• 2006

A patient table considering x-ray transparency, mechanical safety and compact multi-axis moving mechanism has been developed. The goal of medical imaging technology is to keep radiation exposure of patients during x-raying to a minimum. In order to obtain clear pictures at low dose, however, the x-ray table which supports the patient must be sufficiently permeable to radiation to allow good image resolution. The table top is made of low density foam for x-ray transparent effective area and structural aluminum plate to connect moving mechanism under the table, covered with thin carbon fiber. This sandwich construction is very rigid and lightweight, so the table top can handle relatively heavy load comparing to its cantilevered structure which is unavoidable as long as cooperate with C-arm radiography. To verify the design results finite element static analysis and experimental tests have been done. According to the verification the results well satisfy certification guide lines as a medical device.

• Journal of the Optical Society of Korea
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• v.4 no.1
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• pp.66-70
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• 2000

The main problem of image projection on a transmission type holographic screen is color sepa-ration. And it can be overcome by using a long narrow slit type diffuser as a source of the object beam when we record the screen. But that screen is not optimized and so needs changing several conditions. To set up the system many complicate things should be taken into accounted so it is very important to analyze the basic structure by simple concepts and calculations. We designed the system so that recording and projection axis coincide in one line and showed that the analysis of the system is very simple. We did it by a 1st order paraxial approximation calculation and it was good enough to describe the system. The photo-emulsion layer shrinks after processing of the hologram. It induced unsatisfactory color matching at the viewing zone. To overcome this effect, we pre-checked the shrinkage rate of an emulsion layer by experiments and modified the recording set up to compensate for the amount of shrinkage.