• International Journal of Contents
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• v.7 no.2
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• pp.11-16
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• 2011

In this paper, we develop a mobile MAP open API using HTML5 local storage and the W3C geolocation API. The mobile MAP open API consists of the basic JavaScript MAP API, offline navigation API, and multimedia POI (mPOI) API. The basic JavaScript MAP API creates a map and controls, rotates, and overlays data on the map. The offline navigation API is developed using HTML5 local storage and web storage. The mobile web application downloads and stores mPOIs of works of art to local storage or web storage from a web server. The mPOI API is developed using HTML5 video and audio APIs. We develop a mobile art park guidance application using the developed mobile MAP open API.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.5
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• pp.539-545
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• 2015

Deduplication technique can expand the lifespan and capacity of flash memory-based storage devices by eliminating duplicated write operations. The deduplication techniques can be classified into two approaches, i.e., online and offline approaches. We propose an offline deduplication technique that uses a lightweight hash algorithm, whereas the previous offline technique uses a high-cost hash algorithm. Therefore, the memory space for caching hash values can be reduced, and more pages can be examined for deduplication during short idle intervals. As a result, it can provide shorter write latencies compared to the online approach, and can show low garbage collection costs compared to the previous offline deduplication technique.

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.217-225
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• 2023

This study analyzed the effect of flood level reduction in the case of creating and operating offline storage for the Jangdong district, which can be used as a flood buffer space for the Geumgang River, through one-dimensional unsteady flow numerical simulation. In particular, the sensitivity analysis of changes in the height and width (length) of transverse weirs on flood level changes was performed to provide quantitative information necessary for flood control facility (embankment) design. As a result of analyzing the flood control effect of the offline storage based on the peak flood discharge and level, spatially, the flood control effect at the planned flood buffer space site and the downstream end was confirmed, and it was confirmed that the flood reduction effect at the downstream occurred the most. By design conditions of the transverse overflow weir, the greatest flood reduction effect was found under the condition that the overflow weir height based on the 50-year frequency flood level and the transverse overflow weir width (length) of 125 m were considered. The effect of delaying the time to reach the maximum flood due to the operation of the offline storage site was also presented based on unsteady flow modeling.

• Ecology and Resilient Infrastructure
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• v.10 no.2
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• pp.40-49
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• 2023

To reduce the damage of extreme flooding caused by climate change and to create flood mitigation sections in a nature-friendly riparian area, it is necessary to restore the floodplain area by referring to the past floodplain section of the current inland waterfront area before the levee was built. This study proposed a method of selecting a location for floodplain restoration using old maps of the Geum River study section and analyzed the effect of flood level reduction through unsteady flow numerical simulations using the floodplain as a flood mitigation space. As a result of analyzing changes in the river areas using old maps, the river section was estimated to gradually reduce by 27.8% (1,059,380 m²) in 2020 compared to 1919, and it was found to have an effective storage capacity of 2,200,868 m³ when restored to offline storage. The flood level and discharge control effects analyzed based on HEC-RAS unsteady flow simulation were 16 cm and 219.01 m³/s, respectively, in the downstream cross-section. In the numerical simulation in this paper, the flood mitigation space was applied as an offline reservoir. The effect of reducing the flood level may differ if levee retreat/relocation is applied.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.9
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• pp.1123-1131
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• 2020

The quick-response (QR) code is a two-dimensional barcode which is widely being used. Due to several interesting features such as small code size, high error correction capabilities, easy code generation and reading process, the QR codes are used in many applications. Nowadays, a printed color QR code for offline applications is being studied to improve the information storage capacity. By multiplexing color information into the conventional black-white QR code, the storage capacity is increased, however, it is hard to extract the embedded information due to the color crosstalk and geometrical distortion. In this paper, to overcome these problems, a new type of QR code is designed based on the CMYK color model and the local spatial searching as well as the global spatial matching is introduced in the reading process. These results in the recognition rate increase. Through practical experiments, it is shown that the proposed algorithm can perform the bit recognition rate improvement of about 3% to 5%.

• Structural Monitoring and Maintenance
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• v.7 no.4
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• pp.345-365
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• 2020

At present, many machine leaning and data mining methods are used for analyzing and predicting structural response characteristics. However, the platform that combines big data analysis methods with online and offline analysis modules has not been used in actual projects. This work is dedicated to developing a multifunctional Hadoop-Spark big data platform for bridges to monitor and evaluate the serviceability based on structural health monitoring system. It realizes rapid processing, analysis and storage of collected health monitoring data. The platform contains offline computing and online analysis modules, using Hadoop-Spark environment. Hadoop provides the overall framework and storage subsystem for big data platform, while Spark is used for online computing. Finally, the big data Hadoop-Spark platform computational performance is verified through several actual analysis tasks. Experiments show the Hadoop-Spark big data platform has good fault tolerance, scalability and online analysis performance. It can meet the daily analysis requirements of 5s/time for one bridge and 40s/time for 100 bridges.

• Journal of Digital Contents Society
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• v.13 no.1
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• pp.75-81
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• 2012

SSDs(Solid State Drives) have many attractive features such as high performance, low power consumption, shock resistance, and low weight, so they replace HDDs to a certain extent. An SSD has FTL(Flash Translation Layer) which emulate block storage devices like HDDs. A garbage collection, one of major functions of FTL, effects highly on the performance and the lifetime of SSDs. However, there is no de facto standard for new garbage collection algorithms. To solve this problem, we propose trace driven offline optimal algorithms for garbage collection of FTL. The proposed algorithm always guarantees minimal number of erase operation. In addition, we verify our proposed algorithm using TPC trace.

• ETRI Journal
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• v.34 no.3
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• pp.482-484
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• 2012

With the rapid progress of wireless mobile communications, the authenticated key agreement (AKA) protocol has attracted an increasing amount of attention. However, due to the limitations of bandwidth and storage of the mobile devices, most of the existing AKA protocols are not suitable for wireless mobile communications. Recently, Lo and others presented an efficient AKA protocol based on elliptic curve cryptography and included their protocol in 3GPP2 specifications. However, in this letter, we point out that Lo and others' protocol is vulnerable to an offline password guessing attack. To resist the attack, we also propose an efficient countermeasure.

• Ecology and Resilient Infrastructure
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• v.11 no.1
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• pp.24-24
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• 2024

• Journal of Internet Computing and Services
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• v.13 no.4
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• pp.83-93
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• 2012

HTML5 has developed not to have browser dependancy considering interoperability as same as maintaining compatability with lower versions of HTML. HTML5, the newest web standardization is on going of being structured. Along with the smart phone boom, HTML5 is spotlighted because it can be applied to cross platforms in mobile web environments. Specially the local Storage that has been listed in new features in HTML5 supports offline function for web application that enables web application to be run even when the mobile is not connected to 3G or wifi. With Local storage, development of server-independent web application can be possible. However Local storage stores plaintext data in it without applying any security measure and this makes the plaintext data dangerous to security threats that are already exist in other client side storages like Cookie. In the paper we propose secure Local storage methods to offer a safe way to store and retrieve data in Local storage guaranteeing its performance. Suggested functions in this paper follow localStorage standard API and use a module that provide cryptographic function. We also prove the efficiency of suggested secure Local storage based on its performance evaluation with implementation.