• Restorative Dentistry and Endodontics
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• v.30 no.6
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• pp.486-492
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• 2005

The purpose of this study was to compare the shaping ability of the two different Ni-Ti file systems and the two different engine systems in simulated canals. A total of four groups of each 10 were tested. Each group was instrumented with HeroShaper and Endo-Mate2 (Croup HE), HeroShaper and Tecnika (Croup HT), ProFile and Endo-Mate2 (Group PE), and ProFile and Tecnika (Croup PT). Canal preparation time was recorded. The images of pre- and post- instrumented root canals were scanned and superimposed. The amounts of increased width and centering ratio were measured and calculated at apical 1, 3 and 5mm levels. These data were statistically analyzed with one-way ANOVA and Duncan's multiple range test The results of this study were as fellows ; 1. Canal preparation time of HT group was the shortest (p<0.05). 2. The amount of increased canal width in HE group was significantly larger than PT group at apical 1mm level (p<0.05) At apical 3mm level, PT group was significantly smaller than other groups (p<0.05). At apical 5mm level, PE group was significantly larger than PT group (p<0.05). 3. The amount of centering ratio in HE group was significantly larger than other groups (p<0.05). At apical 5mm level, HT group was significantly larger than PE group and PT group (p<0.05). Under the condition of this study, torque-controlled endodontic motor is safer than no torque controlled motor, especially when the active file is used.

• Restorative Dentistry and Endodontics
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• v.13 no.1
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• pp.91-101
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• 1988

The purpose of this study was to evaluate Ultrasonic devices in root canal enlargement, about the effects on the canal shape and on the cutting ability beyond the curvature in curved canals. 180 resin blocks with $40^{\circ}$ curvature in apical third and 16mm long canal were made of epoxy resin and smooth broaches. These blocks were devided into six groups. According to the devices (ENAC$^{(R)}$, HARMOSONIC$^{(R)}$, Sonic Air MM 3000$^{(R)}$) and files (Zipperer file, H-file, Flexofile, K-file, Sharper file), five groups were instrumented one minute with # 15 files, then the enlarged size was measured. And # 20 files were used again in the same groups, then the enlarged size was measured. In control group, the time which was taken to enlarge the canal from # 15 to # 20 by hand technique was measured. The data was analyzed statistically. Then the enlarged shapes were evaluated in six groups with the stereomicroscope and recorded in ideal and non-ideal canal shape to compare the effects of ultrasonic devices on the canal shape. Only the ideal shaped canals were used in the study whether the cutting ability beyond the curvature in curved canals was, or not. The files with whole flutes, no flutes, and flutes in apical 5mm only were used. The weight differences of pre-and post-instrumentation by Sonic Air MM 3000$^{(R)}$ for two minutes were compared. The results were as follow: 1. Intracanal instrumentation for 1 minute with ultrasonic devices using # 15 and # 20 file in curved root canal of the epoxy resin block can not reach to the next file size. 2. Sonic Air MM 3000$^{(R)}$ shows higher cutting ability than the other two devices (p=0.001), however the percentage of non-ideal canal shape was the highest. 3. Two ultrasonic devices except Sonic Air MM 3000 considered normal in ideal canal shaping ability. 4. little cutting ability was shown beyond the curvature of curved canals.

• Restorative Dentistry and Endodontics
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• v.32 no.6
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• pp.530-541
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• 2007

Currently, various Nickel-Titanium rotary files are used in endodontic treatment, but there is no one perfect system that can be applied to any clinical situation. Therefore, the combined uses of various file systems which can emphasize the advantages of each system are introduced as hybrid instrumentation. The ProTaper system is efficient in body shaping and apical pre-enlargement but is reported to have more possibility of transportation and produce more aberrations and deformation in more or less severe curved canals. Recently, new ProTaper system(ProTaper Universal) with different configuration and cross-sectional design to overcome the week points of ProTaper have been marketed. The purpose of this study was to compare and evaluate the shaping abilities of ProTaper, ProTaper Universal system, and two hybrid methods using S-series of ProTaper Universal and Hero Shaper or ProFile. The time lapses for instrumentation were measured and the used files were inspected for distortion. The pre- and post-instrumented root canals were scanned and superimposed to evaluate the aberrations and reduction of root canal curvature and change of radius of canal curvature. The increased canal width and apical centering ratio were calculated at 1, 2, 3, 4 and 5 mm levels from apical foramen. Under the conditions of this study, the ProTaper Universal seems to have better shaping ability than ProTaper in terms of instrumented width and instrumentation time. It may be suggested that the ProTaper Universal system is efficient as much as hybrid instrumentation using ProTaper and other constant-tapered NiTi file systems in highly experienced operators.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.555-558
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• 2009

In this paper, stealth technology is investigated with RCS(Radar Cross Section) reduction to minimize detection range of retroreflective echoes from enemy. Most RCS reduction comes from shaping. RAM(Radar Absorbing Materials) are applied only in areas where there are special problems. Therefore, we designed and fabricated a RAM that has absorption ability higher than 17 dB at 94 GHz for RF stealth in millimeter wave range. As a result, detection range of enemy can be reduced in the 62 percent range by using a developed RAM.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1180-1187
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• 2020

A team of operators is required for nuclear power plant operation, and communication between the operators is an important aspect of the team's ability to successfully carry out tasks. It has been difficult to evaluate the quality of this communication though, and as the relationship between communication quality and team performance has yet to be clarified, it has not been applied to most human reliability analysis (HRA) methodologies. This study investigates the relationship between the quality of communication and team performance using data from a full-scope training simulator of a digital main control room (MCR). Two important characteristics of communication were considered to determine quality: each operator's ability to self-confirm the status of a given task in a digital MCR, and the type of communication, as divided into 1-way, 2-way, and 3-way between operators. To measure team performance, the concept of an unsafe act was employed, which is defined as a human error that has the potential to negatively affect plant safety. Analysis results showed that the communication quality and team performance were related to each other. With this more clearly defined relationship, the results of this study can be applied to related performance shaping factors to improve HRA.

• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.141-152
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• 1992

Four endodontic instruments from different manufacturers(K - file, Hedstrom - file, K - flex - file, Cavi - Endo) were used to shape 80 mesial canals of extracted posterior teeth. The instrument's ability to enlarge and shape the canals as the original canal shape was assessed by superimposing radiographs of canals obtained before and after canal shaping. The results were as follows 1. Hedstrom - file enlarged canals greater than K - file, K - flex - file, and Cavi - Endo(P<0.05). There are no differences in canal enlargement among K - flex, K - flex - file, and Cavi - Endo(P<0.05). 2. All the instruments showed no difference in canal enlargement between convex side and concave side of B point in proximal and clinical radiographic views, but at the concave side of C point canals were enlarged greater than at the convex side(proximal view of K - file: P<0.05, the others: P<0.01). 3. There was no difference m canal enlargement between convex side and concave side in proximal view of A and D points of K - file and K - flex - file(P<0.05). But in clinical view, canal enlargement at convex side of A point and concave side of D point was greater than that at concave side of A point and convex side of D point respectively. 4. Hedstrom - files showed greater canal enlargement at convex side of A points and concave side of D points (P<0.05 or P<0.01). Cavi - Endo showed no difference in canal enlargement between convex side and concave side at A and D points in proximal view(P<0.05). Bur canal enlargement was greater at concave side than at convex side of D point in clinical view. 5. K - file and Cavi - Endo showed no differences in canal enlargement between convex and concave side in proximal and clinical view (P<0.05). K - flex - file showed greater canal enlargement at concave side in proximal and clinical view(P<0.0:5). Hedstrom file showed no difference in canal enlargement between convex side and concave side in proximal view, but showed greater canal enlargement at concave side in clinical view(P<0.05).

• Restorative Dentistry and Endodontics
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• v.46 no.2
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• pp.16.1-16.11
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• 2021

Objectives: The aim of this study was to evaluate the shaping ability of the TruShape and Reciproc Blue systems and the apical extrusion of debris after root canal instrumentation. The ProTaper Universal system was used as a reference for comparison. Materials and Methods: Thirty-three mandibular premolars with a single canal were scanned using micro-computed tomography and were matched into 3 groups (n = 11) according to the instrumentation system: TruShape, Reciproc Blue and ProTaper Universal. The teeth were accessed and mounted in an apparatus with agarose gel, which simulated apical resistance provided by the periapical tissue and enabled the collection of apically extruded debris. During root canal preparation, 2.5% sodium hypochlorite was used as an irrigant. The samples were scanned again after instrumentation. The percentage of unprepared area, removed dentin, and volume of apically extruded debris were analyzed. The data were analyzed using 1-way analysis of variance and the Tukey test for multiple comparisons at a 5% significance level. Results: No significant differences in the percentage of unprepared area were observed among the systems (p > 0.05). ProTaper Universal presented a higher percentage of dentin removal than the TruShape and Reciproc Blue systems (p < 0.05). The systems produced similar volumes of apically extruded debris (p > 0.05). Conclusions: All systems caused apically extruded debris, without any significant differences among them. TruShape, Reciproc Blue, and ProTaper Universal presented similar percentages of unprepared area after root canal instrumentation; however, ProTaper Universal was associated with higher dentin removal than the other systems.

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.316-327
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• 1995

The purpose of this study was to evaluate canal shaping ability and canal angulation change of K-file, straight endosonic K-file and pre curved endosonic K-file. Twenty staight canals and thirty curved canals were selected and divided into five groups according to canals curvature and canal instrumentation method. VI group was prepared by straight endosonic K-file and H1 group by K-file in straigt canals. V2 group was instrumented by straight endosonic K-file, V3 group by pre curved endosonic K-file and H2 group by precurved K-file in curved canals. Radiographs of canals were obtained before and after canal shaping. And postoperative radiographs were compared with preoperative radiographs using superimposition method. The results obtained were as follows ; l. In straight canals, K-file group demonstrated lager percentage of canal enlargement than endosonic K-file group on facial view, but reverse results exhibit on mesial view. 2. In curved canals, precurved K-file group showed largest percentage of canal enlargement, followed by precurved endosonic K-fine group and straight endosonic K-file group was smallest. 3. Percantage of canal enlargement at convex side was greater than at concave side in apical portion of each group. Especially in straight endosonic K-file group, percantage of canal enlargement at convex side and concave side showed sharply difference. 4. In angulation change, the straight endosonic K-file group exhibited the greatest its change, followed by precurved endosonic K-file group and precurved K-file group was the least. Above results suggest that K-file is more effective endodontic instrument than endosonic K-file, and that precurved file is effective for canal shaping in curved canal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6B
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• pp.433-442
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• 2012

We have proposed a solution to multicast services and an advanced quality of service (QoS) mechanism on a packet transport system (PTS) based on PBB-TE. The point-to-multipoint (PtMP) connection in the PBB-TE system have been realized by grouping point-to-point (PtP) PTL trunks and mapping a BSI onto the PtP PTL trunks using a multicast backbone destination address. To provide end-to-end QoS of the PtMP services, the hierarchical QoS scheme for backbone service instances and connection-oriented paths has been implemented in the PTS. For providing different capabilities for service selection and priority selection, the PTS offers to customers three basic types of the port-based, C-tagged, and S-tagged service interface defined by the IEEE 802.1ah. To offer to customers different capabilities of the layer 3 applications and services, moreover, an IP-flow service interface have been added. In order to evaluate traffic performance for PtMP services in the PTS, the PtMP throughputs for the link capacity of 1 Gbps at the four service interfaces were measured in the leaves of the ingress edge node, the transit node, and the egress edge node. The throughputs were about 96 % because the B-MAC overhead of 22 bytes occupies 4% of the 512-byte packet. The QoS performance is ability to guarantee an application or a user a required bandwidth, and could be evaluated by the accuracy of policing or shaping. The accuracy of the policing scheme and the accuracy of the shaping scheme were 99% and 99.3% respectively.

• Restorative Dentistry and Endodontics
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• v.45 no.3
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• pp.30.1-30.11
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• 2020

Objectives: This micro-computed tomographic (CT) study aimed to compare the shaping abilities of ProTaper Next (PTN), One Shape (OS), and One Curve (OC) files in 3-dimensionally (3D)-printed mandibular molars. Materials and Methods: In order to ensure standardization, 3D-printed mandibular molars with a consistent mesiobuccal canal curvature (45°) were used in the present study (n = 18). Specimens were instrumented with the OC, OS, or PTN files. The teeth were scanned pre- and post-instrumentation using micro-CT to detect changes of the canal volume and surface area, as well as to quantify transportation of the canals after instrumentation. Two-way analysis of variance was used for statistical comparisons. Results: No statistically significant differences were found between the OC and OS groups in the changes of the canal volume and surface area before and after instrumentation (p > 0.05). The OC files showed significantly less transportation than the OS or PTN systems for the apical section (p < 0.05). In a comparison of the systems, similar values were found at the coronal and middle levels, without any significant differences (p > 0.05). Conclusions: These 3 instrumentation systems showed similar shaping abilities, although the OC file achieved a lesser extent of transportation in the apical zone than the OS and PTN files. All 3 file systems were confirmed to be safe for use in mandibular mesial canals.