• The Journal of the Korean dental association
• /
• v.21 no.5 s.168
• /
• pp.395-402
• /
• 1983

The purpose of this study was to apply the etched metal ceramometal retainer using a composite resin and acid-etch procedure with minimal tooth reduction of abutments for the replacement of one missing anterior or posterior tooth. Author obtained the following conclusions. 1. conservation of tooth structure and minimal chair time and patient expense were the primary advantages of etched metal retainer. 2. This fixed partial denture permitted good esthetic results. 3. This retainer was successfully applied for the replacement of one missing anterior or posterior tooth. 4. Proper retainer etching ws an important procedure. 5. Etched castings could be applied to periodontal splinting and post orthodontic fixation.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.756-757
• /
• 2006

P/M enables the economical production of components for many kinds of gears. Functionally, the sub gear requires high tooth accuracy and bending fatigue strength. The whole tooth profile was sized after sintering to satisfy the gear tooth accuracy specification. The part was redesigned to reduce machining requirements. The required bending fatigue strength was achieved through appropriate material choice and induction of compressive residual stress by shotpeening after carburizing. The P/M sub gear replaced a forged steel gear, satisfied performance requirements, expanded the use of P/M applications and provided over 30% cost reduction.

• Journal of Periodontal and Implant Science
• /
• v.48 no.4
• /
• pp.236-250
• /
• 2018

Purpose: Resorption of the alveolar bone is an unavoidable consequence of tooth extraction when appropriate alveolar ridge preservation (ARP) measures are not taken. The objective of this trial was to test the hypothesis that dimensional changes in the alveolar bone after tooth extraction would be reduced by inserting an equine collagen membrane and a collagen cone to fill and seal the alveolus (as ARP), in comparison to extraction with untreated alveoli. Methods: In this randomized clinical trial, 31 patients were directly treated with the collagen material after extraction of a tooth from the maxilla (the ARP group). Twenty-nine patients served as the control group. After extraction, no further treatment (i.e., no socket preservation measures) was performed in the control group. Changes in the alveolar process immediately after extraction and after an 8 (${\pm}1$)-week healing period were evaluated 3-dimensionally. Blinded analyses were performed after superimposing the data from the digitalized impressions and surfaces generated by cone-beam computed tomography. Results: Both the ARP and control groups showed a reduction of bone in the alveolar area after tooth extraction. However, significantly less bone resorption was detected in the clinically relevant buccal region in the ARP group. The median bone reduction was 1.18 mm in the ARP group and 5.06 mm in the control group (P=0.03). Conclusions: The proposed hypothesis that inserting a combination material comprising a collagen cone and membrane would lead to a difference in alveolar bone preservation can be accepted for the clinically relevant buccal distance. In this area, implantation of the collagen material led to significantly less alveolar bone resorption. German Clinical Trials Register at www.drks.de, DRKS00004769.

• The Journal of Korean Academy of Prosthodontics
• /
• v.28 no.2
• /
• pp.77-90
• /
• 1990

The purpose of this study was to compare the amount of the vertical pin opening of $33^{\circ}$ resin and $0^{\circ}$ resin teeth during processing and to determine whether the changes in tooth contacts by using articulation ribbon and T-Scan system follow any identifiable pattern, and to determine if there is any correlation between the changes in tooth contacts and the amount of the vertical pin opening after processing. Through statistical analyses on the data from this study, the following conclusions were obtained. 1. The amounts of the vertical pin opening were 0.78m, 0.87mm for $0^{\circ}$ teeth and $33^{\circ}$ teeth, respectively. But there was no significant difference between them. 2. The total number of contact points recorded by articulating ribbon after processing was decreased to 442.5% of that before processing. 3. The mean values for the number of contact points per tooth recorded by articulating ribbon after processing were 4.3 for the second molar, 3.8 for the first molar, 1.3 for the second premolar, 0.8 for the first premolar. The reduction of contact points per tooth became greater moving in an anterior direction. 4. The correlation between the reduction of contact points and the amount of the pin opening after processing was not significant. 5. The mean values for the numbers of contact points per tooth recorded by T-Scan system after processing were 2.2, 2.5, 1.0, and 0.5 at the second molar, the first molar, the second premolar, and the first premolar, respectively. 6. The correlation between the number of contact points by using articulating ribbon and TScan system after processing was not significant.

• Journal of Advanced Marine Engineering and Technology
• /
• v.8 no.2
• /
• pp.74-80
• /
• 1984

In the reduction gears for marine propulsion engine such as turbine or high speed diesel engine, the standard involute double helical gears are generally used. However the addendum modification gear can be used in the reduction gear as it has flexibility for gear design on the tooth strength, scoring and operating noise. In this case, the determination of gear shaft bearing load is difficult by the alternation of operating pressure angle. In this paper, the formulas of bearing load according to the arrangements of the reduction gears are derived and the diagrams of operating pressure angle according to the modification coefficient are presented.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.45 no.1
• /
• pp.41-56
• /
• 2018

The purpose of this study was to provide clinical recommendations for restoration with selection of the most similar zirconia crown by 3-dimensional analysis of the shape of the maxillary primary central and lateral incisors in Korean individuals and prefabricated zirconia crowns. The average shape of the sound maxillary primary central and lateral incisors in 300 children was reproduced by 3-dimensional scanning. Zirconia crowns of 4 manufacturers (NuSmile $ZR^{(R)}$ Crown, Cheng $Crowns^{(R)}$, Kinder $Krowns^{(R)}$, and EZ $Pedo^{(R)}$ Crown) were scanned 3-dimensionally, and coordinates for comparison of the shape were measured to evaluate the similarity between the teeth and crowns. The most similar crowns were selected by comparing the mesiodistal length, crown height, crown shape ratio, distance between the same coordinates of a tooth and crown, the radius of curvature of the labial surface, and the volume. As a result of analysis, Cheng $Crowns^{(R)}$ size 3 and NuSmile $ZR^{(R)}$ Crown size 2 were the most similar crowns in the maxillary primary central and lateral incisors, respectively. Scanning the inner surface of the crowns and evaluating the amount of tooth reduction required suggested that an overall lesser amount of tooth reduction compared to that presented by the manufacturer's guidelines should be performed.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.17 no.1
• /
• pp.19-25
• /
• 2007

Among the precision reduction gent drivers lot robot system, the cycloid reducer is well known for it's high performances. Designing this reducer, there are many factors which must be considered. First, a geometrical analysis of tooth shape must be drawn from the basic concept. Second, loads, stresses and modification factors on tooth should be calculated exactly. Finally, a computer software to optimize the design of cycloid tooth needs developing on the basis of the geometric and force equations. In this research, the expert system to design the cycloid reducer was developed using Visual C++ so, the most important factors can be obtained automatically as the user put the simple input data.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.04a
• /
• pp.808-812
• /
• 1996

Reduction gear with internal gear pair need functions such as compact size, high reduction ratios, high transmission efficiency, and low noise. Feasible design region of the internal gear pair with a small tooth difference is extremely limited because the internal gear pair is subject to interference in meshing and cutting. Single-objective optimal design can not simulataneously satisfy the manifold requirements of the internal gear pair and can not determine the economical specification of a pinion cutter. Multi-objective optimal design which include the specification of the pinion cutter in design variables is developed, considering the manufacturing error of an internalgear pair and the re-sharpening of the pinion cutter.

• International Journal of Automotive Technology
• /
• v.8 no.1
• /
• pp.75-82
• /
• 2007

This paper presents practical work on the reduction of gear whine noise. In order to identify the source of the gear whine noise, transfer paths are searched and analyzed by operational deflection shape analysis and experimental modal analysis. It was found that gear whine noise has an air-borne noise path instead of structure-borne noise path. The main sources of air-borne noise were the two global modes caused by the resonance of an axle system. These modes created a vibro-acoustic noise problem. Vibro-acoustic noise can be reduced by controlling the vibration of the noise source. The vibration of noise source is controlled by the modification of structure to avoid the resonance or to reduce the excitation force. In the study, the excitation force of the axle system is attenuated by changing the tooth profile of the hypoid gear. The modification of the tooth profile yields a reduction of transmission error, which is correlated to the gear whine noise. Finally, whine noise is reduced by 10 dBA.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.12
• /
• pp.3227-3235
• /
• 1994

This paper deals with an evaluation of the residual stress due to shot peening induced in a carburized gear tooth and its application to the fatigue crack propagation problem. A practical method is proposed on the basis of the assumption that the residual stress is caused by the difference of volume expansion in the case and the core, and the influence of both the reduction of retained austenite and the strain due to shot peening are considered. The evaluated residual stress is close to the measured stress, though the surface stress is rather overestimated. The stress intensity factor is computed by the influence function method, and it is shown that the factor is decreased by the residual stress in shot peened gear tooth. The shot peening is fairly effective to the reduction of fatigue crack growth rate. The crack propagation is simulated and the resistance due to shot peening is quantitatively demonstrated and discussed.