• Journal of the Korea Society of Computer and Information
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• v.24 no.8
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• pp.9-17
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• 2019

In this paper, we propose a block mapping technique applicable to NAND flash memory. In order to use the NAND flash memory with the operating system and the file system developed on the basis of the hard disk which is mainly used in the general PC field, it is necessary to use the system software known as the FTL (Flash Translation Layer). FTL overcomes the disadvantage of not being able to overwrite data by using the address mapping table and solves the additional features caused by the physical structure of NAND flash memory. In this paper, we propose a new mapping method based on the block mapping method for efficient use of the NAND flash memory. In the case of the proposed technique, the data modification operation is processed by using a blank page in the existing block without using an additional block for the data modification operation, thereby minimizing the block unit deletion operation in the merging operation. Also, the frequency of occurrence of the sequential write request and random write request Accordingly, by optimally adjusting the ratio of pages for recording data in a block and pages for recording data requested for modification, it is possible to optimize sequential writing and random writing by maximizing the utilization of pages in a block.

• International journal of advanced smart convergence
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• v.10 no.1
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• pp.142-150
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• 2021

Open-channel SSD is a new type of Solid-State Disk (SSD) that improves the garbage collection overhead and write amplification due to physical constraints of NAND flash memory by exposing the internal structure of the SSD to the host. However, the host-level Flash Translation Layer (FTL) provided for open-channel SSDs in the current Linux kernel consumes host memory excessively because it use page-level mapping table to translate logical address to physical address. Therefore, in this paper, we implemente a selective mapping table loading scheme that loads only a currently required part of the mapping table to the mapping table cache from SSD instead of entire mapping table. In addition, to increase the hit ratio of the mapping table cache, filesystem information and mapping table access history are utilized for cache replacement policy. The proposed scheme is implemented in the host-level FTL of the Linux kernel and evaluated using open-channel SSD emulator. According to the evaluation results, we can achieve 80% of I/O performance using the only 32% of memory usage compared to the previous host-level FTL.

• Investigative Magnetic Resonance Imaging
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• v.25 no.4
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• pp.300-312
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• 2021

Compressed sensing (CS) has been investigated in magnetic resonance (MR) parametric mapping to reduce scan time. However, the relatively long reconstruction time restricts its widespread applications in the clinic. Recently, deep learning-based methods have shown great potential in accelerating reconstruction time and improving imaging quality in fast MR imaging, although their adaptation to parametric mapping is still in an early stage. In this paper, we proposed a novel deep learning-based framework DEMO for fast and robust MR parametric mapping. Different from current deep learning-based methods, DEMO trains the network in an unsupervised way, which is more practical given that it is difficult to acquire large fully sampled training data of parametric-weighted images. Specifically, a CS-based loss function is used in DEMO to avoid the necessity of using fully sampled k-space data as the label, thus making it an unsupervised learning approach. DEMO reconstructs parametric weighted images and generates a parametric map simultaneously by unrolling an interaction approach in conventional fast MR parametric mapping, which enables multi-tasking learning. Experimental results showed promising performance of the proposed DEMO framework in quantitative MR T1ρ mapping.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.2
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• pp.237-243
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• 2011

Various standard terminologies in medical field are composed individually to different structure. Therefore, information on crosswalking between the terminologies is needed to combine and use the terminologies. Lots of mapping tools have been developed and used to create the information. However, since those tools deal with specific terminologies, the information is restrictly created. To overcome this problem, some tools have been developed, which perform mapping tasks by composing various terminologies. However, the tools also have difficulty of composing automatically the terminologies because the terminologies have different structures. Therefore, in this paper, we propose a method for composing and using the terminologies in the developed mapping system with keeping the original structure of the terminologies. In the proposed method, additional terminologies could be added on the mapping system and used by making metadata involving information on location and structure of the terminologies. And the mapping system could cope flexibly with the changes of the structure or context of the terminologies. Moreover, various types of mapping information could be defined and created in the system because mapping data are constructed as triplets in ontology. Therefore, the mapping data can be transformed and distributed in different formats such as OWL, RDF, and Excel. Finally, we confirmed the usefulness of the mapping system based on the proposed method through the experiments about creating mapping data.

• Korean Journal of Remote Sensing
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• v.37 no.3
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• pp.577-589
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• 2021

Drone mapping systems can be applied to many fields such as disaster damage investigation, environmental monitoring, and construction process monitoring. To integrate individual sensors attached to a drone, it was essential to undergo complicated procedures including time synchronization. Recently, a variety of composite sensors are released which consist of visual sensors and GPS/INS. Composite sensors integrate multi-sensory data internally, and they provide geotagged image files to users. Therefore, to use composite sensors in drone mapping systems, mapping accuracies from composite sensors should be examined. In this study, we analyzed the mapping accuracies of a composite sensor, focusing on the data acquisition area and pre-calibration effect. In the first experiment, we analyzed how mapping accuracy varies with the number of ground control points. When 2 GCPs were used for mapping, the total RMSE has been reduced by 40 cm from more than 1 m to about 60 cm. In the second experiment, we assessed mapping accuracies based on whether pre-calibration is conducted or not. Using a few ground control points showed the pre-calibration does not affect mapping accuracies. The formation of weak geometry of the image sequences has resulted that pre-calibration can be essential to decrease possible mapping errors. In the absence of ground control points, pre-calibration also can improve mapping errors. Based on this study, we expect future drone mapping systems using composite sensors will contribute to streamlining a survey and calibration process depending on the data acquisition circumstances.

• Journal of applied mathematics & informatics
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• v.30 no.3_4
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• pp.685-691
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• 2012

We define and characterize a somewhat fuzzy precontinuous mapping and a somewhat fuzzy preopen mapping on a fuzzy topological space. Besides, some interesting properties of those mappings are given.

• Journal of applied mathematics & informatics
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• v.32 no.1_2
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• pp.203-209
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• 2014

We define and characterize a somewhat fuzzy ${\gamma}$-irresolute continuous mapping and a somewhat fuzzy irresolute ${\gamma}$-open mapping on a fuzzy topological space.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.451-454
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• 2004

We studied on the performance optimized synthesis and mapping of design on to one or more FPGA device. Our multi-phased approach optimized the key parameters that affect performance by adequately modeling the impact on wire length, routability, and performance during technology mapping to produce designs that have high performance and high routability potential.

• East Asian mathematical journal
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• v.28 no.5
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• pp.569-578
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• 2012

In this paper, the necessary and sufficient conditions for the strong convergence of a modified Mann iteration process to a fixed point of an asymptotically demicontractive mapping in real Banach spaces are considered. Presented results improve and extend the results of Igbokwe [3], Liu [4], Moore and Nnoli [6] and Osilike [7].

• Kyungpook Mathematical Journal
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• v.59 no.4
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• pp.665-678
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• 2019

We construct an iteration scheme involving a hybrid pair of mappings, one a single-valued asymptotically nonexpansive mapping t and the other a multivalued nonexpansive mapping T, in a complete CAT(0) space. In the process, we remove a restricted condition (called the end-point condition) from results of Akkasriworn and Sokhuma [1] and and use this to prove some convergence theorems. The results concur with analogues for Banach spaces from Uddin et al. [16].