• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.3
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• pp.121-130
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• 2017

NAND flash memory has advantages of non-volatility, little power consumption and fast access time. However, it suffers from inability that does not provide to update-in-place and the erase cycle is limited. Moreover, the unit of read/write operation is a page and the unit of erase operation is a block. Therefore, erase operation is slower than other operations. The AGC, the proposed garbage collection policy focuses on not only garbage collection time reduction for real-time guarantee but also wear-leveling for a flash memory lifetime. In order to achieve above goals, we define three garbage collection operating modes: Fast Mode, Smart Mode, and Wear-leveling Mode. The proposed policy decides the garbage collection mode depending on system CPU usage rate. Fast Mode selects the dirtiest block as victim block to minimize the erase operation time. However, Smart Mode selects the victim block by reflecting the invalid page number and block erase count to minimizing the erase operation time and deviation of block erase count. Wear-leveling Mode operates similar to Smart Mode and it makes groups and relocates the pages which has the similar update time. We implemented the proposed policy and measured the performance compare with the existing policies. Simulation results show that the proposed policy performs better than Cost-benefit policy with the 55% reduction in the operation time. Also, it performs better than Greedy policy with the 87% reduction in the deviation of erase count. Most of all, the proposed policy works adaptively according to the CPU usage rate, and guarantees the real-time performance of the system.

• Journal of Computational Design and Engineering
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• v.2 no.4
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• pp.206-217
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• 2015

This paper presents a complete S-shape feed rate scheduling approach (CSFA) with confined jerk, acceleration and command feed rate for parametric tool path. For a Non-Uniform Rational B-Spline (NURBS) tool path, the critical points of the tool path where the radius of curvature reaches extreme values are found firstly. Then, the NURBS curve is split into several NURBS sub-curves or blocks by the critical points. A bidirectional scanning strategy with the limitations of chord error, normal/tangential acceleration/jerk and command feed rate is employed to make the feed rate at the junctions between different NURBS blocks continuous. To improve the efficiency of the feed rate scheduling, the NURBS block is classified into three types: short block, medium block and long block. The feed rate profile corresponding to each NURBS block is generated according to the start/end feed rates and the arc length of the block and the limitations of tangential acceleration/jerk. In addition, two compensation strategies are proposed to make the feed rate more continuous and the arc increment more precise. Once the feed rate profile is determined, a second-order Taylor's expansion interpolation method is applied to generate the position commands. Finally, experiments with two free-form NURBS curves are conducted to verify the applicability and accuracy of the proposed method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.304-305
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• 2018

Recently, Industrial-IoT (IIoT) solutions accounted for up to 55% in 2016 and technological innovation and various new business models are being developed. In this paper, apply IIoT device in various environments and implement an ontology system that can interwork with block type IIoT device to easily add / change / delete sensor. The proposed system consists of IIoT device, block-type module, and ontology server. When the block-type module is connected to the IIoT device, the appropriate driver is installed and the firmware is downloaded through the ontology server. Even if a block is added / changed / deleted, it can be updated automatically. Through experiments, we confirmed that the normal operation of the server and the updating and downloading of software are implemented normally.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2005.11a
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• pp.229-234
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• 2005

The purpose of this study is to analyze a Characteristics of block formation and commercialization of residential books commercial area along urban arteries on Teheran-ro in Seoul. 'Teheran-ro' is selected as a case site to analyze the characteristics of residential blocks commercial area along urban arteries. The study analyzes the characteristics of the street network and block formation in commercial area along arteries and rear residential blocks, and commercialization of residential blocks commercial area along urban arteries according to the characteristics of street network and block formation. The analysis about block formation progress about i ) a street network and block formation, ii ) the scale of blocks, iii) division of lots, iv) lots system. The analysis about commercialization of residential blocks commercial area progress about i) a street network and block formation, ii) a density of building, iii) a use of building

• 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.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.4
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• pp.275-281
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• 2016

One of the most important things for quality to meet ship-production schedule is an accuracy control. A ship is assembled by welding through whole production process, so it is important that loss by correction will not happen as much as possible by using some engineering skills like reverse design, reverse setting and margin for thermal shrinkage. These efforts are a quite effective in fabrication stages, but not in erection stages. If a ship block which consists of common steel is exposed to directional solar radiation, its dimensional accuracy will change high as time by its thermal expansion coefficient. Therefore, the measuring work would be often done at dawn or evening even with having a very accurate device. In this study, an FE analysis method is developed to solve this problem. It can change measured data affected by solar thermal distortion to ones not, even though ship-block is measured at an arbitrary time. It will use the time when measuring, the direction of block and the weather record by satellites. It is confirmed by a comparison between measured data of a ship-block and the result by suggested analysis method. Furthermore, a pre-processing system is also developed for fast application of the suggested analysis method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.375-380
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• 2012

In this study, dynamic load and dynamic contact force between a building block and wire ropes of a goliath crane are calculated during lifting or turn-over of a building block for the design of an optimal lug arrangement system. In addition, a multibody dynamics kernel for implementing the system were developed. In the multibody dynamics kernel, the equations of motion are constructed using recursive formulation. To evaluate the applicability of the developed kernels, the interferences and dynamic contact force between the building block and wire ropes were calculated and then the hull structural analysis for the block was performed using the calculation result.

• Journal of Digital Contents Society
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• v.12 no.4
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• pp.559-565
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• 2011

In this paper, I propose a distributed game server system which has flexibility of enormous game character's processing in MMORPG using block scheme. I proposed game servers in distributed system grouped with zone which charge of each map, and the game servers in this zone divide game map into several unit blocks and process distributing blocks to game servers according to its performance. I proposed distributed game server system using block scheme can add/drop game map to/from easily through block process method in game and communication servers. Therefore, my proposed system can enormous character processing and add user created game map to existed game map easily in the future as well. Also, my scheme increases the system utilization and upgrades system stability by dynamic distribution of game map according to the number of characters and performance of servers.

• The KIPS Transactions:PartA
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• v.17A no.2
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• pp.63-72
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• 2010

Recently, the need for multimedia devices, such as digital TV, and camcorder has increased. These devices provide many services on multimedia files such as playing, recording, and editing. Throughout these services, in case of storing edited large-scaled multimedia files, existing file system have several capability problems that are taking too much time and requiring disk I/O. In this paper, we propose the use of Linux Ext2 file system based 'Block-Link file (BL-file) system' in order to solve these problems. For the BL-file system, when editing and storing large-scaled files, there is no data input or output but only modification of the metadata. Additionally, by sharing data blocks between multimedia files, we can save disk spaces. Moreover, because the managing of data block sharing information is more convenient than the existing FWAE technique, we can lessen system overhead. The BL-file system is based on Ext2 file system and implemented in a Linux environment, and the usefulness of the proposed technique is validated by applying the Linux multimedia file-editing tool 'Avidemux'.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.2
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• pp.29-37
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• 2020

This paper proposes a multiple-relay-assisted single side band (SSB) space frequency block code (SFBC) single carrier (SC)-frequency division multiple access (FDMA) system and measures the performance of SSB SFBC SC-FDMA transmission system with the signal-to-noise power ratio SNR) between relays and a destination station. As we know, the performance of relay-assisted transmission systems can be easily improved by re-transmitting to the destination station after applying block code to the recovered transmitted signals of relays. In this paper, the performance improvement of the relay-assisted SSB SC-FDMA system can be obtained without any significant increase of system computational complexity by implementing block code with the complex conjugates symmetric characteristic of SSB system. The simulation result shows that the SNR performance of the proposed multiple-relay-assisted SSB SFBC SC-FDMA system is about 4 dB better than the performance of the single-relay-assisted SSB SC-FDMA system at the symbol error rate of 10^-2.