• Electronics and Telecommunications Trends
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• v.26 no.5
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• pp.55-65
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• 2011

요즘 신산업으로 떠오르고 있는 개인 유전체 분석이나 차세대 시퀀싱 기술과 같은 고성능 컴퓨팅 응용들은 data-intensive한 작업들을 요구하며, 이러한 응용을 지원하기 위한 고성능 파일 시스템 기술에 대한 연구들이 다수 진행 중이다. 그러나 그 결과물들은 업체별로 보유한 고유 기술로서, 상호 호환성 등의 문제로 인해 표준화의 필요성이 제기되어 왔다. 현재 파일 시스템과 관련하여 거의 모든 IT 업체에서 사용하고 있는 실질적인 표준은 NFS(Network File System)이다. IETF(Internet Engineering Task Force)에서는 이러한 요구사항들을 반영하여 2010년에 NFSv4.1 표준을 공표하였고, 특히 I/O 성능을 향상시키기 위한 pNFS(parallel NFS)는 NFSv4.1의 핵심 기능으로서 다수업체들과 연구기관들에서 많은 관심을 받고 있다. 본 고에서는 pNFS 표준화 및 연구개발 동향과 관련된 이슈들에 대해 기술하고자 한다.

• Journal of Ocean Engineering and Technology
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• v.11 no.2
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• pp.145-153
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• 1997

This paper constructs a data base to create the Hull lines prior to piece manufacture and nesting steps with a personal computer using the data of created as the advanced software, TRIBON. The lines are plotted smoohtly, which are called the spline. The S/W is excellentlt estimated on the ptrcision among shipping exclusive S/W, which are currentlyused So, the S/W is mainly used as as shipping CAD program. High-cost H/W and high-performance S/W(TRIBON etc.) sre used with the bases of technique and capital power in the big shipbuilding yard; but small but small and medium-sized shipbuilding yard and related companycan't purchase dueto the high-cost product. To bring upthe small and medium sized shipbuilding yard lacking little competitive power, the data base S/W is joined with the CADRA of graphic S/W and is developed to create the Hull lines to be needed on as automatic cutting process usiing the personal computer.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.3
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• pp.191-198
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• 2009

The FAT (File Allocation Table) compatible file system has been widely used in mobile devices and memory cards because of its data exchangeability among numerous platforms recognizing the FAT file system. By the way. modern embedded systems have tough demands for instant power failure recovery and superior performance for multimedia applications. The key issue is how to achieve the goals of superior write performance and instant booting capability while controlling compatibility issues. To achieve the goals while controlling compatibility issues. we devised a temporary meta-data journaling scheme for a FAT compatible file system. Benchmark results of the scheme implemented in a FAT compatible file system shows that it really improves write performance of the FAT file system by converting small random write for meta-data update to a large sequential write in journaling area. Also, it provides natural way to implement the instant booting capability. Nevertheless, the file system compatibility is temporarily compromised by the scheme because it stores updated meta-data in the temporary journaling area rather than to their original locations. However, the compatibility can be fully recovered at any time by journal-flushing that copies meta-data in journaling area to their original locations. Generally, the journal-flushing is done before un-mounting a memory card so that it can be used in other mobile devices which recognized FAT file system but not the temporary meta-data journaling scheme.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.139-140
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• 2007

• Journal of Drive and Control
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• v.9 no.4
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• pp.79-87
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• 2012

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.6 s.312
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• pp.11-19
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• 2006

The recent video coding standard H.264 employs the rate-distortion optimization (RDO) method for choosing the best coding mode; however, it causes a large amount of encoding time. Thus, in order to reduce the encoding time, we need a fast mode decision algorithm. In this paper, we propose a fast inter mode decision algorithm considering quantization parameter (QP). The occurrence of best modes depends on QP. In order to reflect these characteristics, we consider the coded block pattern (CBP) which has 0 value when all quantized discrete cosine transform (DCT) coefficients are zero. We also use the early SKIP mode decision and early $16{\times}16$ mode decision methods. By computer simulations, we have verified that the proposed algorithm requires less encoding time than the fast inter mode decision method of the H.264 reference software for the Baseline and Main profiles by 19.6% and 18.8%, respectively.

• Restorative Dentistry and Endodontics
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• v.31 no.1
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• pp.11-19
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• 2006

The purpose of this study was to compare and evaluate the shaping abilities of various hybrid instrumentation method using constant tapered file systems with $ProTaper\^{(R)}$ S1 and the difference between experts and inexperienced clinicians in use of NiTi file. Three hybrid methods used in this study were composed of $ProTaper\^{(R)}\;S1\;and\;K-Flexofile\^{(R)}\;(group S),\;ProTaper\^{(R)}\;S1\;and\;HeroShaper\^{(R)}\;(group\;H),\;and\;ProTaper\^{(R)}\;S1\;and\;ProFile\^{(R)}\;(group\;P)$respectively. The $ProTaper\^{(R)}$-alone method (group C) was introduced as a control group. After canal preparation, the lapse of time was recorded. The images of pre- and post-operative canal were scanned and superimposed. Amounts of instrumented canal widths and centering ratio were measured at apical 1, 2 and 3 mm levels and statistical analysis was performed In this study. both of the group C and S took more time to prepare canals than other groups, Inexperienced operators required more time for the entire preparation with the groups C and H than the experienced (p<0.05). And the centering ratio of group P were preferable to $ProTaper\^{(R)}$-alone method or the hybrid technique using stainless steel files. As such, within experienced operators, group H also showed better results in addition to the group P. Under these condition, the hybrid methods of each the $ProFile^{(R)}$ system and $HeroShaper^{(R)}$ with ProTaper are recommendable comparative to $ProTaper\^{(R)}$-alone method. According to the results, the hybrid instrumentation method is a more appropriate method of canal preparation than single file system for narrow or curved canals.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.4
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• pp.233-241
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• 2022

Purpose: The purpose of this study was to assess the dimensional change of 3D-printed dentures after post-curing. Materials and Methods: The upper and lower dentures were designed in Exocad DentalCAD software and exported as STL files. The upper and lower dentures were printed from 10 STL files using a DLP-type dental 3D printer. The printed upper and lower dentures were cleaned, and a scan file was created using a model scanner before and after post-curing. The dimensional change was evaluated by superimposing the scanned denture files before and after post-curing and measuring the distance between measurement points on the denture. SPSS was used for statistics, and the level of significance was 5%. Results: The maxillary denture reduced in size during post-curing, with the most notable color change occurring in the posterior palatal region. The reduction in anteroposterior maxillary denture length (A-D, A-E, A-F), as well as the distance between the first molars on both sides (B-C), was statistically significant. After post-curing, the mandibular denture showed more noticeable color change in the posteriorly buccal and lingual region. The decrease of length on the posterior (A-M, A-D, A-E, A-L, A-H, A-I, H-I) and lingual (J-K, L-M) sides of the denture were statistically significant. Conclusion: There was significant dimensional change in both the length and width of the 3D-printed maxillary and mandibular dentures after post-curing in this experiment. Consequently, it is seemed necessary to develop post-curing techniques and materials that reduce such denture deformation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.5
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• pp.24-30
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• 2010

In this paper, we described intra prediction which is the one of techniques to be used for higher compression performance in H.264/AVC and proposed the design of intra predictor for efficient intra prediction mode processing. The proposed system is consist of processing elements, precomputation processing elements, an intra prediction controller, an internal memory and a register controller. The proposed system needs the reduced the computation cycles by using processing elements and precomputation processing element and also needs the reduced the number of access time to external memory by using internal memory and registers architecture. We designed the proposed system with Verilog-HDL and verified with suitable test vectors which are encoded YUV files. The proposed architecture belongs to the baseline profile of H.264/AVC decoder and is suitable for portable devices such as cellular phone with the size of $176{\times}144$. As a result of experiment, the performance of the proposed intra predictor is about 60% higher than that of the previous one.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.12
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• pp.1201-1207
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• 2012

This study was performed to develop a high-efficiency submersible nonclogging pump impeller. Toward this end, we simulated the effect of some parameters such as the outlet position of a blade ($h_I$), outlet width of a blade ($b_2$), and hub profile on the pump efficiency by using the commercial codes ANSYS CFX and BladeGen. The results showed that the pump efficiency was proportional up to $h_I$= 38 mm and $b_2$= 55 mm. It remained constant over these values. However, the head and shaft power were proportional to $h_I$ and $b_2$ in the simulated ranges. The effects of hub profile changes on the pump efficiency were relatively small compared to those of the other parameters.