• Restorative Dentistry and Endodontics
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• v.45 no.2
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• pp.22.1-22.10
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• 2020

Objectives: This study investigated the influence of glide path size and operating kinetics on the time to reach the working length and the fracture resistance of Twisted File (TF) and Endostar E3 files. Materials and Methods: A total of 120 mandibular single-rooted premolars were selected. Two methods of kinetic motion (TF adaptive and continuous rotary motion) and file systems (TF and Endostar E3) were employed. The files were used in root canals prepared to apical glide path sizes of 15, 20, and 25. The time taken to reach the working length and the number of canals used before the instrument deformed or fractured were noted. Fractured instruments were examined with scanning electron microscopy. Results: The TF system took significantly more time to reach the working length than the Endostar E3 system. Both systems required significantly more time to reach the working length at the size 15 glide path than at sizes 20 and 25. A greater number of TFs than Endostar E3 files exhibited deformation, and a higher incidence of instrument deformation was observed in adaptive than in continuous rotary motion; more deformation was also observed with the size 15 glide path. One TF was fractured while undergoing adaptive motion. Conclusions: No significant difference was observed between continuous rotary and adaptive motion. The TF system and adaptive motion were associated with a higher incidence of deformation and fracture. Apical glide path sizes of 20 and 25 required significantly less time to reach the working length than size 15.

• The KIPS Transactions:PartA
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• v.9A no.3
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• pp.287-294
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• 2002

In this paper we propose a new mechanism for file system using a dynamic bitmap assignment. While traditional file systems rely on a fixed bitmap structures for metadata such as super block, inode, and directory entries, the proposed file system allocates bitmap and allocation area depends on file system features. Our approach gives a solution of the problem that the utilization of the file system depends on the file size in the traditional file systems. We show that the proposed mechanism is superior in the efficiency of disk usage compared to the traditional mechanisms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.1
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• pp.404-421
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• 2020

A reversible data hiding scheme in JPEG compressed bitstreams is proposed, which could avoid decoding failure and file expansion by means of removing of bitstreams corresponding to high frequency coefficients and embedding of secret data in file header as comment part. We decode original JPEG images to quantified 8×8 DCT blocks, and search for a high frequency as an optimal termination point, beyond which the coefficients are set to zero. These blocks are separated into two parts so that termination point in the latter part is slightly smaller to make the whole blocks available in substitution. Then spare space is reserved to insert secret data after comment marker so that data extraction is independent of recovery in receiver. Marked images can be displayed normally such that it is difficult to distinguish deviation by human eyes. Termination point is adaptive for variation in secret size. A secret size below 500 bits produces a negligible distortion and a PSNR of approximately 50 dB, while PSNR is also mostly larger than 30 dB for a secret size up to 25000 bits. The experimental results show that the proposed technique exhibits significant advantages in computational complexity and preservation of file size for small hiding capacity, compared to previous methods.

• Restorative Dentistry and Endodontics
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• v.37 no.2
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• pp.79-83
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• 2012

Objectives: The purpose of this study was to evaluate the relation between intentionally induced internal stress and cyclic fatigue failure of .06 taper ProFile. Materials and Methods: Length 25 mm, .06 taper ProFile (Dentsply Maillefer), and size 20, 25, 30, 35 and 40 were used in this study. To give the internal stress, the rotary NiTi files were put into the .02 taper, Endo-Training-Bloc (Dentsply Maillefer) until auto-stop by torque controlled motor. Rotary NiTi files were grouped by the number of induced internal stress and randomly distributed among one control group and three experimental groups (n = 10, Stress 0 [control], Stress 1, Stress 2 and Stress 3). For cyclic fatigue measurement, time for separation of the rotary NiTi files was recorded. The fractured surfaces were observed by field emission scanning electron microscope (FE-SEM, SU-70, Hitachi). The time for separation was statistically analyzed using two-way ANOVA and post-hoc Scheffe test at 95% level. Results: In .06 taper ProFile size 20, 25, 30, 35 and 40, there were statistically significant difference on time for separation between control group and the other groups (p < 0.05). Conclusion: In the limitation of this study, cyclic fatigue failure of .06 taper ProFile is influenced by internal stress accumulated in the files.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.659-669
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• 1997

The goals of root canal instrumentation are complete debridement of pulp tissue, removal of microbes and affected dentin, and proper cleaning and shaping of the root canal space before obturation. Instrumentation with stainless steel files has been shown to produce undesirable results in canals, regardless of the improved technique or modified file type used. Nickel-Titanium(Ni-Ti) alloy has been shown to be exceptionally elastic, having a lower bending moment and lower permanent set after torsion, compared with similar gauge stainless steel. The purpose of this study was to evaluate the change of root canal prepared by Ni-Ti rotary and stainless steel instruments. Thirty-four single rooted teeth of similar shape and canal size were divided into three groups. The teeth were scanned by computed tomography before instrumentation. In group 1, canals were instrumented using a step-back technique with K-file. In group 2, canals were prepared with K-flex file using the same technique as group 1. Group 3 was prepared with nickel-titanium(Ni-Ti) rotary instrument using a manufacture's instruction. Instrumented teeth were again scanned using computed tomography, and reformated images of the uninstrumented canals were compared with images of the instrumented canals. K-flex file and Ni-Ti file caused significantly less canal transportation than K-file in the 8mm root canal section from the apex(p<0.05). K-flex file and Ni-Ti file produced more centered canal preparation than K-file in the 2mm section(p<0.05). Ni-Ti file maintained more precisely the center of the canal than K-flex file in the 10mm section (p<0.05). There was no difference in the removed volume of canals among each groups.

• Restorative Dentistry and Endodontics
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• v.26 no.3
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• pp.200-205
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• 2001

이 연구의 목적은 만곡 근관에서 다양한 크기로 근첨을 형성하였을 때 형성 전후의 근관의 전이 정도를 분석하고자 하는 것이다. 만곡된 근관을 가진 투명한 레진블럭 상에서 ProFile .06 taper와 K-flexofile을 이용하여 각각 근관형성을 시행하고 이를 똑같은 위치가 재현가능한 고정틀에 위치시킨 후 사진의 이중노출 기법을 이용하여 근관형성 전후의 근관의 전이정도를 분석한 결과 다음과 같은 결과를 얻었다. 1. ProFile의 경우 형성된 근관이 taper한데 비해 K-flexofiles의 경우 형성된 근관이 taper하지 못하고 확대가 더 컸다. K-flexofiles의 경우 ProFile의 경우보다 근첨 0~6mm 부위에서 유의하게 더 굵었다(p<0.05). 2. 만곡외측으로의 확대양상은 ProFile의 경우 대체적으로 taper하나 근첨 3~4mm부위가 약간 굵었다. K-flexofile의 경우 만곡외측으로의 확대양상은 taper하지 못하고 불규칙하였다. ProFile에 비해 근첨 0~2mm에서 유의하게 확대가 더 컸다(p<0.05). 3. 만곡내측으로의 확대양상은 모든 군에서 taper하였으나 K-flexofile의 경우 ProFile의 경우보다 확대가 더 컸다. K-flexofile의 경우 ProFile에 비해 근첨 3~5mm부위에서 유의하게 확대가 더 컸다(p<0.05).

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.475-478
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• 2004

The DCSU performs satellite payload data acquisition and storage functions before sending the data to the ground station. While imaging, the DCSU makes a file per each input channel and store into memory stack. For the successful imaging mission, proper DCSU mission parameters should be uploaded before the mission such as file name, file size, output channel for the download transmission and so on. This paper will describe the DCSU recording mechanism and some notices that might be helpful for the ground operators.

• The KIPS Transactions:PartC
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• v.9C no.6
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• pp.961-968
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• 2002

This paper proposes a new access method which is to considered the high variability in World Wide Web and manage the web cache space. Instead of using a single cache, we divide a cache and store all documents according to their file types. Proposed method was compares with current cache management policies using LFU, LRU and SIZE base algorithm. Using two different workload, we show the improvement hitting ratio and byte hitting ratio through simulating on the file type caching.

• Journal of information and communication convergence engineering
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• v.9 no.5
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• pp.567-572
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• 2011

As the mobile devices have powerful CPUs and memories, it is possible to carry the large volumes of design drawings, such as DXF files, on mobile devices. However, since the format of a DXF file is the ASCII, it has the shortcoming where the size of a file is larger than a binary formatted file and it is difficult to display the entities of drawings quickly on mobile devices. In this paper, we design the DXF manager system on a smart phone. To speed up the rate of the display and panning, the DXF manager hires the spatial index, the fixed grid file. We also implement the system on the Samsung Omnia-1$^{(R)}$ to exploit the Windows Mobile$^{(R)}$ operating system.

• Journal of Korea Multimedia Society
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• v.4 no.6
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• pp.489-499
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• 2001

This paper presents the SIC(Size-Interval-Count) prefetching system that can record the file access patterns of applications within a relatively small space of memory based on the repetitiveness of the file access patterns. The SICPS(SIC Prefetching System) is based on knowledge-based prefetching methods which includes high correctness in predicting future accesses of applications. The proposed system then uses the recorded file access patterns, referred to as "SIC access pattern information", to correctly predict the future accesses of the applications. The proposed prefetching system improved the response time by about 40% compared to the general file system and showed remarkable memory efficiency compared to the previously knowledge-based prefetching methods.