• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.136-140
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• 2015

Linux environment that is commonly used at embedded systems supports various file systems as Ext2, FAT, NTFS, etc. The file system that is equiped on the embedded system is mostly implemented on mini hard disk or flash memory. The types of the file system of the system make an effect on the performance of a application programs. The factors of file system performance on a same media are block read, block write and block free time. On these factors, block read and block free time are not so different according to the type of file systems. This paper evaluates the performance benchmark of file systems supported by linux about block allocation and write performance. The results obtained from various experiments shows the characteristics of each file system.

• Journal of Korea Multimedia Society
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• v.12 no.12
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• pp.1710-1717
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• 2009

Flash memory has become the most important storage media in mobile devices along with its attractive features such as low power consumption, small size, light weight, and shock resistance. However, a flash memory can not be written before erased because of its erase-before-write characteristic, which lead to some garbage collection when there is not enough space to use. In this paper, we propose a novel garbage collection scheme, called block-level buffer garbage collection. When it is need to do merge operation during garbage collection, the proposed scheme does not merge the data block and corresponding log block but also search the block-level buffer to find the corresponding block which will be written to flash memory in the next future, and then decide whether merge it in advance or not. Our experimental results show that the proposed technique improves the flash performance up to 4.6% by reducing the unnecessary block erase numbers and page copy numbers.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.1 s.145
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• pp.103-118
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• 2006

At the initial design stage, the generation process of the production material information of a building block and the simulation process of the block erection, which are required to perform the production planning and scheduling, have been manually performed using 2D drawings, based on the data of parent ships, and subjective intuition from past experience. To make these processes automatic, the accurate generation method of the production material information and the convenient simulation method of the block erection based on the initial hull structural model(3D CAD model), were developed in this study. Here, the initial hull' structural model was generated from the initial hull structural CAD system early developed by us. To evaluate the developed methods. these methods were applied to corresponding processes of a deadweight 300,OOOton VLCC. As a result. it was shown that the production material information of a building block can be accurately generated and the block erection can be conveniently simulated in the initial design stage.

• Coupled systems mechanics
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• v.8 no.4
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• pp.351-375
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• 2019

The present work investigates the use of a rigid rocking block as a tool to reduce vibrations in a frame structure. The study is based on a simplified model composed by a 2-DOF linear system, meant to represent a general M-DOF frame structure, coupled with a rocking rigid block through a linear visco-elastic device, which connects only the lower part of the 2-DOF system. The possibility to restrain the block directly to the ground, by means of a second visco-elastic device, is investigated as well. The dynamic response of the model under an harmonic base excitation is then analysed in order to evaluate the effectiveness of the coupling in reducing the displacements and the drift of the 2-DOF system. The nonlinear equations of motion of the coupled assemblage 2-DOF-block are obtained by a Lagrangian approach and then numerically integrated considering some reference mechanical and geometrical quantities as variable parameters. It follows an extensive parametric analysis, whose results are summarized through behaviour maps, which portray the ratio between the maximum displacements and drifts of the system, with and without the coupling with the rigid block, for several combinations of system's parameters. When the ratio of the displacements is less than unity, the coupling is considered effective. Results show that the presence of the rocking rigid block improves the dynamics of the system in large ranges of the characterizing parameters.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.2
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• pp.85-96
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• 2008

One of the typical methods to prevent tampering and reverse engineering on executable codes is to encrypt them. This paper proposes a code block cipher method based on key chaining to encrypt the code. The block cipher by key chaining has been known to be inadequate for encrypting the code with control transfer, even though the key chaining has advantage of hiding the keys in blocks and making the individual keys different from block to block. This paper proposes a block transformation and duplication method to apply the block cipher by key chaining to the executable codes with control transfer instructions, and shows the idea works with the MIPS instruction set.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.5
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• pp.314-322
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• 2022

During the shipbuilding process, many blocks are moved between shipyard workshops by block carrying vehicles called a transporter. Because block logistics management is one of the essential factors in enhancing productivity, it is necessary to manage block information with the transporter that moves it. Currently, because a large amount of data per day are collected from sensors attached to blocks and transporters via IoT infrastructure installed in shipyards, automated methods are needed to analyze them. Therefore, in this study, we developed an algorithm that can automatically match the transporter and the working block based on the GPS sensor data. By comparing the distance between the transporter and the blocks calculated from the Haversine formula, the block is found which is moved by the transporter. In this process, since the time of the measured data of moving objects is different, the time standard for calculating the distance must be determined. The developed algorithm was verified using actual data provided by the shipyard, and the correct result was confirmed with the distance based on the moving time of the transporter.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2567-2572
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• 2011

It is the key component that motor block system affect safety and performance of railway. It is very important to examine the performance of motor block for improvement of safety and reliability of rolling stock. As such, the motor block is an essential part of rolling stock. But provisioning quantities and spare quantities depend on the operator' experience. There are many problems that occur lots of spare or lack of spare. If there are lots of spare, it is difficult to keep the circumstance by cost issues. On the contrary, if there are lack of spare, it may have a adverse effect on the whole railway. Thus, this study offers method to estimate optimal spare of motor block using the analysis of data related with Failure rate, MTBF, standards and guidelines. And we expect this study to contribute to determine optimal spare parts.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.4
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• pp.297-305
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• 2018

In a shipyard, block lifting is an important process in the production of ships and offshore structures. Block lifting is a sensitive process because lifting blocks have to be erected with exact positions and orientations. If we use a numerical method for the process, it is important to find tensions of wires and positions of equalizers to maintain the initial equilibrium position of the block. At this time, equations of motion of the block should be solved to calculate the initial equilibrium position of the block. Because the solving technique changes according to the number of equalizers, a suitable equation for the corresponding problem is required. In this study, three types of equations are proposed to find the initial equilibrium position of the block according to the number of equalizers. The Newton-Raphson's method is used to solve nonlinear simultaneous equations and the optimization method is used to determine the appropriate solution to the undetermined problem. To evaluate the applicability of the proposed methods, the dynamic simulations are performed using the tensions calculated from the proposed methods, and the results are discussed. The results show that the proposed methods can be effectively used to determine initial equilibrium position of the block for the block lifting.

• The Korean Journal of Pain
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• v.33 no.2
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• pp.144-152
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• 2020

Background: Hemidiaphragmatic paralysis, a frequent complication of the brachial plexus block performed above the clavicle, is rarely associated with an infraclavicular approach. The costoclavicular brachial plexus block is emerging as a promising infraclavicular approach. However, it may increase the risk of hemidiaphragmatic paralysis because the proximity to the phrenic nerve is greater than in the classical infraclavicular approach. Methods: This retrospective analysis compared the incidence of hemidiaphragmatic paralysis in patients undergoing costoclavicular and supraclavicular brachial plexus blocks. Of 315 patients who underwent brachial plexus block performed by a single anesthesiologist, 118 underwent costoclavicular, and 197 underwent supraclavicular brachial plexus block. Propensity score matching selected 118 pairs of patients. The primary outcome was the incidence of hemidiaphragmatic paralysis, defined as a postoperative elevation of the hemidiaphragm > 20 mm. Factors affecting the incidence of hemidiaphragmatic paralysis were also evaluated. Results: Hemidiaphragmatic paralysis was observed in three patients (2.5%) who underwent costoclavicular and 47 (39.8%) who underwent supraclavicular brachial plexus blocks (P < 0.001; odds ratio, 0.04; 95% confidence interval, 0.01-0.13). Both the brachial plexus block approach and the injected volume of local anesthetic were significantly associated with hemidiaphragmatic paralysis. Conclusions: The incidence of hemidiaphragmatic paralysis is significantly lower with costoclavicular than with supraclavicular brachial plexus block.

• Fibers and Polymers
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• v.3 no.1
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• pp.8-13
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• 2002

The effect of block sequence on the self-assembly of ABC-type triblock copolymers in the ordered state is investigated using an isothermal-isobaric molecular dynamics simulation. The block sequence has an important effect ,on the ]norphology of ABC triblock copolymers. Different morphologies are observed depending on the block sequence as well as the block composition. The triblock copolymers with the volume fraction of 1 : 1 : 1 ($f_A$=$f_B$=$f_C$= 0.33) show the three phase and four layered lamellar structures irrespective of the block sequence. The $A_{32}$$B_{16}$$C_{32}$triblock copolymer with $f_B$=0.2 shows a morphology In which cylinders of midblock B are formed at the interface between A and C lamellae, whereas the morphology of triblock copolymer $B_{16}$$C_{32}$ $A_{32}$ and $C_{32}$ $A_{32}$ $B_{16}$ show a cylindrical core-shell structure and a lamellar type morphology, respectively. The $A_{20}$$B_{40}$$C_{20}$the triblock copolymer with the block B as a major component shows a tricontinuous structure, whereas both $B_{40}$$C_{20}$$A_{20}$ and $C_{20}$$A_{20}$$B_{40}$ triblock coolymers exhibit the lamellar structures. When the block B has larger volrome fraction with $f_B$=0.75, the matrix is composed of block B, and other two blocks A and C form spherical domains.