• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.5
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• pp.1141-1149
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• 2016

Deduplicated filesystem can reduce usage of storage. However, it be able to recover deleted block. We studied sanitization of deduplicated filesystem, LessFS which is based on FUSE(Filesystem in USErspace). First, we show a vulnerability recover deleted data in the deduplicated filesystem. We implement sanitization of deduplicated filesystem considering the part of fingerprint DB with data blocks. It takes 60~70 times compared to without sanitization. Which means access time to fingerprint DB and overhead derived from increase of number of chunk have a critical impact on sanitization time. But in case of more than 65,536 Byte of chunksize, it is faster than normal filesystem without deduplication.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.5955-5962
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• 2014

Generally, the frame design of a vehicle is a critical technology that plays an important role in the racing and high performance sports car market. The high performance of race car frame means that it requires high torsional stiffness because it directly affects the cornering behavior of the race car. The optimal design for the frame of a low-cost single seat race car was carried out using the DOE (Design Of Experiments) with Taguchi's orthogonal array and FEM (Finite Element Method) analysis to secure sufficient torsional stiffness in this paper. According to the results by DOE and FEM analysis, the optimal design case produced improved 10.7% and 14.5% improvement in each stiffness-to-weight ratio and frame weight than in the early design step. Therefore, this paper shows that the optimal design with Taguchi's orthogonal array is very useful and effective for designing a tubular space frame of a low-cost single seat race car in the early design step.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.112-118
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• 2013

The selection of appropriate ground motions and reasonable modification are becoming increasingly critical in reliable prediction on seismic performance of structures. A widely used amplitude scaling approach is not sufficient for robust structural evaluation considering a site specific seismic hazard because only one spectral value is matched to the design spectrum typically at the structural fundamental period. Hence alternative approaches for ground motion selection and modifications have been suggested. However, there is no means to evaluate such methodologies yet. In this study, it is focused to describe the main questions resided in the amplitude scaling approach and to propose a regression model for structural damage as point of comparison. Spectrum compatible approach whose resulting spectrum matches the design spectrum at the entire range of the structural period is considered as alternative to be compared to the amplitude scaling approach. The design spectrum is generated according to ASCE7-05.

• Journal of Information Technology Services
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• v.11 no.4
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• pp.251-262
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• 2012

Unit testing is one of the test levels, which tests an individual unit or a group of related units. Recently, in Agile Development or Safety-critical System Development, the unit testing plays an important role for the qualities. According to the definition of unit testing, it is supposed to be done by the developers of units. That is because test models for the unit testing refers to the structure of units, and others but its original developers hardly can understand the structures. However, in practice, unit testing is often asked to be done without the original developers. For example, it is when faults are revealed in customer sites and the development team does not exit any more. In this case, instead of original developers, other developers or test engineers take a product and test it. The unit testing done by a non-developer, who is not the original developer, would cause some difficulties or cause more cost. In this paper, we tests an open source, JTopas, as a non-developer, with building test models, implementing test codes, and executing test cases. To fit this experiment to practical testing situations, we designed it based on the practices of unit testing, which were surveyed through SPIN(Software Process Improvement Network). This paper analyzes which part of unit testing done by non-developers needs more effort compared to the unit testing done by original developers. And it concludes that Agile Development contributes on reducing the extra effort caused by non-developers, since it implements test codes first before developing source code. That means all the units have already included their own tests code when they are released.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.5
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• pp.1-11
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• 2001

In the past, abundant and clean water was available for paper mills'use. However, the growth of population and industry made water less available nowadays. Also, environmental regulation limits wastewater discharge, which affects mill operation cost. Therefore, paper mills are under pressure to use more recycled water and mill system closure. As a result, chemical and physical parameters of water are changing and new environment if being created for microorganisms in paper mill system as well. The more soluble or suspended organic materials are increased as more water is recycled and less or scarce dissolved oxygen is available, depending on the degree of recycled water usage. Microorganism flora ill paper mill system will be a1so shifted according to the environmental change of mill system. Anaerobic bacteria, including sulfate reducing bacteria (SRB), will be dominant in the system as very low or almost no oxygen available in the system. Nevertheless, it is common in domestic paper mills that employ the same and old biocides as a means of microbial control, and microbiological control is often less recognized or even neglected. The right biocide selection for increased reductive environment of mills is critical for operation and estimated loss from paper quality defects such as sheet break, holes due to microbiological cause is tremendous compared to the microbiological control cost. It is imperative to investigate and diagnosis the environmental change of mills for right control of cumbersome microorganisms. Several useful diagnosis tools, including new technology employing OFM(Optical Fouling Monitor) in situ, are illustrated.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.281.2-281.2
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• 2013

Since heavy metal ions included in water or food resources have critical effects on human health, highly sensitive, rapid and selective analysis for heavy metal detection has been extensively explored by means of electrochemical, optical and colorimetric methods. For example, quantum dots (QDs), such as semiconductor QDs, have received enormous attention due to extraordinary optical properties including high fluorescence intensity and its narrow emission peaks, and have been utilized for heavy metal ion detection. However, the semiconductor QDs have a drawback of serious toxicity derived from cadmium, lead and other lethal elements, thereby limiting its application in the environmental screening system. On the other hand, Graphene oxide (GO) has proven its superlative properties of biocompatibility, unique photoluminescence (PL), good quenching efficiency and facile surface modification. Recently, the size of GO was controlled to a few nanometers, enhancing its optical properties to be applied for biological or chemical sensors. Interestingly, the presence of various oxygenous functional groups of GO contributes to opening the band gap of graphene, resulting in a unique PL emission pattern, and the control of the sp2 domain in the sp3 matrix of GO can tune the PL intensity as well as the PL emission wavelength. Herein, we reported a photoluminescent GO array on which heavy metal ion-specific DNA aptamers were immobilized, and sensitive and multiplex heavy metal ion detection was performed utilizing fluorescence resonance energy transfer (FRET) between the photoluminescent monolayered GO and the captured metal ion.

• Korean Journal of Materials Research
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• v.19 no.1
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• pp.1-6
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• 2009

In this study, the stress-strain response and the cracking behaviors of ITO film on a PET substrate are investigated. The cracking behaviors of ITO thin films deposited on a thermoplastic semi-crystalline polymer developed for flexible display applications was investigated by means of tensile experiments equipped with an electrical measurement apparatus and an in-situ optical microscope. Electrical resistance increased gradually in the elastic-to-plastic transition region of the stress strain curves and cracks formed. Numerous cracks were found in this region, and the increase of the resistance was linked to the cracking of ITO thin films. Upon loading, the initial cracks perpendicular to the tensile axis were observed at about 1% of the total strain. They propagated to the entire sample width as the strain increased. The spacing between the horizontal cracks is thought to be determined by the fracture strength and the thickness of the ITO film as well as by the interfacial strength between the ITO and PET. The effect of the strain rate on the cracking behavior was also investigated. The crack density increased as the strain increased. The spacing between the horizontal cracks (perpendicular to the stress axis) increased as the strain rate decreased. The increase of the crack density as the strain rate decreased can be attributed to the higher fraction of the plastic strain to the total strain at a given total strain. The higher critical strain for the onset of the increase in the resistance and the crack initiation of the ITO/PET with a thinner ITO film (300 ohms/sq.) suggests a higher strength of the thinner ITO film.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.935-943
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• 1988

The forming limit diagram is assessed as a means of estimating the forming characteristics of sheet metal and is usually determined experimentally. The strain rates used in the determination are likely to be low. However, often in practice, the strain rates are much higher, so if forming limit diagram is determined at low rates, it may not be appropriate. This paper reconsiders the forming limit diagram for mild steel and aluminum sheet up to variation in strain rate from 10$^{-2}$ sec to 20/sec where its forming has been carried out under oil pressure using a hydraulic bulge test with circular and elliptical dies. To obtain higher strain rate, an impact bulge test had been employed with the same die sets as those used for a hydraulic bulge test. The results obtained are as follows: (1) As the strain rate increases, the fracture pressure increases and the polar height at fracture decreases. (2) Experiment has shown that, in the positive quadrant of the forming limit diagram, the diagram is lowered with increasing strain rate and the effect of strain rate changes according to strain paths and materials..

• KIISE Transactions on Computing Practices
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• v.21 no.9
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• pp.604-609
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• 2015

The use of Operating System(OS) virtualization is increasing as it provides many useful features such as efficient use of hardware(HW), easy system migration, and isolation between virtual spaces which prevents errors effecting each other. Recent development in HW has made it possible to use OS virtualization in embedded systems. However, implementing OS virtualization means that a multiple number of schedulers are layered in a system, rendering it difficult to analyze the schedulability of the system and errors are easily produced. Errors in safety critical embedded systems can cause serious damage to life and property; thus, the hierarchical schedulability must be verified. In this paper, we propose a framework which supports formal modeling and verification of hierarchical scheduling systems with UPPAAL.

• Smart Media Journal
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• v.6 no.2
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• pp.33-41
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• 2017

Railway point machines act as actuators that provide different routes to trains by driving switchblades from the current position to the opposite one. Since point failure caused by the aging effect can significantly affect railway operations with potentially disastrous consequences, replacement detection of point machine at an appropriate time is critical. In this paper, we propose a replacement condition detection method of point machine in railway condition monitoring systems using electrical current signals, after analyzing and relabeling domestic in-field replacement data by means of OLAP(On-Line Analytical Processing) operations in the multidimensional data cube into "does-not-need-to-be replaced" and "needs-to-be-replaced" data. The system enables extracting suitable feature vectors from the incoming electrical current signals by DWT(Discrete Wavelet Transform) with reduced feature dimensions using PCA(Principal Components Analysis), and employs SVM(Support Vector Machine) for the real-time replacement detection of point machine. Experimental results with in-field replacement data including points anomalies show that the system could detect the replacement conditions of railway point machines with accuracy exceeding 98%.