• Journal of Adhesion and Interface
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• v.7 no.2
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• pp.1-11
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• 2006

Interfacial evaluation of the untreated and treated Jute and Hemp fibers reinforced different matrix polypropylene-maleic anhydride polypropylene copolymer (PP-MAPP) composites were investigated by micromechanical technique and dynamic contact angle measurement. For the statistical tensile strength of Jute and Hemp fibers, bimodal Weibull distribution was fitted better than the unimodal distribution. The acid-base parameter on the interfacial shear strength (IFSS) of the natural fiber composites was characterized by calculating the work adhesion, $W_a$. The effect of alkaline, silane coupling agent on natural fibers were obtained with changing MAPP content in PP-MAPP matrices. Alkaline treated fibers made the surface energy to be higher due to removing the weak boundary layers and thus increasing surface area, whereas surface energy of silane treated Jute and Hemp fibers decreased due to blocked high energy sites. MAPP in the PP-MAPP matrix caused the surface energy to increase due to introduced acid-base sites. Microfailure modes of two natural fiber composites were observed clearly differently due to different tensile strength of natural fibers.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.2
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• pp.151-160
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• 2017

Growing demand and rapid development of the synthetic fiber rope in mooring system have taken place since it has been used in deep water platform lately. Unlike a chain mooring, synthetic fiber rope composed of lightweight materials such as Polyester(polyethylene terephthalate), HMPE(high modulus polyethylene) and Aramid(aromatic polyamide). Non-linear stiffness and another failure mode are distinct characteristics of synthetic fiber rope when compared to mooring chain. When these ropes are exposed to environmental load for a long time, the length of rope will be increased permanently. This is called 'the creep phenomenon'. Due to the phenomenon, The initial characteristics of mooring systems would be changed because the length and stiffness of the rope have been changed as time goes on. The changed characteristics of fiber rope cause different mooring tension and vessel offset compared to the initial design condition. Commercial mooring analysis software that widely used in industries is unable to take into account this phenomenon automatically. Even though the American Petroleum Institute (API) or other classification rules present some standard or criteria with respect to length and stiffness of a mooring line, simulation guide considers the mechanical properties that is not mentioned in such rules. In this paper, the effect of creep phenomenon in the fiber rope mooring system under specific environment condition is investigated. Desiged mooring system for a Mobile Offshore Drilling Unit(MODU) with HMPE rope which has the highest creep is analyzed in a time domain in order to investigate the effects creep phenomenon to vessel offset and mooring tension. We have developed a new procedure to an analysis of mooring system reflecting the creep phenomenon and it is validated through a time domain simulation using non-linear mooring analysis software, OrcaFlex. The result shows that the creep phenomenon should be considered in analysis procedure because it affects the length and stiffness of synthetic fiber rope in case of high water temperature and permanent mooring system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10B
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• pp.644-654
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• 2007

ZigBee is one of wireless communication standards and many applications based on Zigbee have been developing for commercial applications. Most of those applications require links to Internet like Zigbee service gateways. However, ZigBee service gateway should provides following functions to be effectively utilized itself: translation of messages between diverse ZigBee application profiles and message formats used in Internet, addition/removal of a new ZigBee service without stopping existing services according to addition/removal of a Zigbee node, and no transmission of unwanted packets to ZigBee network. Therefore, this paper proposes a new type of ZigBee Service Gateway, called ZiGate to provide the functions. The proposed ZiGate is capable of re-configurating message translation modules required in case of addition/removal of nodes and doesn't transmit unnecessary packets to the ZigBee networks by synchronizing itself with ZigBee network. And ZiGate provides translation modules between messages defined in Zigbee application profiles and both text-based and binary-based messages used in Internet. In this paper we implements the ZiGate and evaluates it on the test bed. This evaluations show that the proposed ZiGate works efficiently.

• Journal of KIISE:Software and Applications
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• v.31 no.5
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• pp.677-696
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• 2004

Component-based software engineering (CBSE) composes reusable components and develops applications with the components. CBSE is admitted to be a new paradigm that reduces the costs and times to develop software systems. The high quality of component designs can be assured if the consistency and correctness among the elements of a component are verified with formal specifications. Current formal languages for components include only some parts of contracts between interfaces, structural aspects and behavioral aspects of component, component-based system, component composition and variability. Therefore, it is not adequate to use current formal languages in all steps of a component design process. In this paper, we suggest a formal language to specify component designs Component-Z. Component-Z extends Object-Z, adds new notations to specify components. It can be possible to specify interfaces, the inner structure of a component, inner workflows, and workflows among interfaces with Component-Z. In addition, Component-Z provides the notations and semantics to specify variability with variation points, variants and required interfaces. The relation between interfaces and components is defined with mapping schemas. Parallel operator is used to specify component composition. It can be possible to describe deployed components with the specifications of component-based systems. Therefore, the formal specification language proposed in this paper can represent all elements to design components. In the case study, we specify an account management system in a bank so that we show that Component-Z can be used in all steps of component design.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.555-567
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• 2010

Unlike single-hop systems, multi-hop systems that use relay nodes assign a part of the overall resources to relay communications. If efficient resource allocation schemes are not adopted, this leads to a loss of resources. Moreover, because we may not be able to guarantee high-link performance due to the adjacent-cell interference in relay-based cellular systems, resource efficiency can be severely decreased. In this paper, we propose efficient resource allocation schemes for downlink relay-based networks in 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution)-Advanced systems. Unlike conventional schemes that have static resource regions for each data link, the proposed schemes dynamically allocate the resources of each link to resource blocks, by considering the channel state and the capacity of each link. We also propose resource overlapping schemes in which two different links overlap at the same resource region, so as to improve cell or user throughput performance. The proposed resource overlapping schemes do not require additional processes such as interference cancellation in users, thank to considering additional interference from resource overlapping in advance.

• The KIPS Transactions:PartC
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• v.10C no.6
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• pp.799-808
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• 2003

Existing security solutions such as Firewell and IDS (Intrusion Detection System) have a trouble in getting accurate detection rate about new attack and can not block interior attack. That is, existing securuty solutions have various shortcomings. Shortcomings of these security solutions can be supplemented with mechanism which guarantees an availability of systems. The mechanism which guarantees the survivability of node is various, we approachintrusion telerance using real time response mechanism. The monitoring code monitors related resources of system for survivability of vulnerable systm continuously. When realted resources exceed threshold, monitoring and response code is deployed to run. These mechanism guarantees the availability of system. We propose control mathod about resource monitoring. The monitoring code operates with this method. The response code may be resident in active node for availability or execute a job when a request is occurred. We suggest the node survivability mechanism that integrates the intrusion tolerance mechanism that complements the problems of existing security solutions. The mechanism takes asvantage of the automated service distribution supported by Active Network infrastructure instead of passive solutions. The mechanism takes advantage of the automated service distribution supported by Active Network infrastructure instead of passive system reconfiguration and patch.

• The KIPS Transactions:PartB
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• v.11B no.2
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• pp.233-240
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• 2004

This paper presents a method to implicitly resolve ambiguities using dynamic incremental clustering in Korean-to-English and Japanese-to-English cross-language information retrieval (CLIR). The main objective of this paper shows that document clusters can effectively resolve the ambiguities tremendously increased in translated queries as well as take into account the context of all the terms in a document. In the framework we propose, a query in Korean/Japanese is first translated into English by looking up bilingual dictionaries, then documents are retrieved for the translated query terms based on the vector space retrieval model or the probabilistic retrieval model. For the top-ranked retrieved documents, query-oriented document clusters are incrementally created and the weight of each retrieved document is re-calculated by using the clusters. In the experiment based on TREC test collection, our method achieved 39.41% and 36.79% improvement for translated queries without ambiguity resolution in Korean-to-English CLIR, and 17.89% and 30.46% improvements in Japanese-to-English CLIR, on the vector space retrieval and on the probabilistic retrieval, respectively. Our method achieved 12.30% improvements for all translation queries, compared with blind feedback in Korean-to-English CLIR. These results indicate that cluster analysis help to resolve ambiguity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.76-85
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• 2017

In this study, to evaluate the mechanical properties of fiber-reinforced cement composites by strain rate, hydraulic rapid loading test system was developed. And compressive and tensile strength of the hooked steel fiber and polyamide fiber reinforced cement composite were evaluated. As a result, the compressive strength, strain capacity and elastic modulus were increased with increasing strain rate. The effect of compressive strength by type and volume fraction of fibers was not significant. The dynamic increase factor(DIF) of the compressive strength was higher than that of the CEB-FIP model code 2010 and showed a trend similar to that of ACI-349. The tensile strength and strain capacity were increased with increasing strain rate. The hooked steel fibers were drawn from the matrix. The tensile strength and strain capacity of hooked steel fiber reinforced cement composites were increased as the strain rate increased. The tensile strength and deformation capacity of the fiber reinforced cement composites were increased. And, hooked steel fibers were drawn from the matrix. On the other hand, because the bonding properties of polyamide fiber and matrix is large, polyamide fiber was cut-off with out pullout from matrix. The strain rate effect on the tensile properties of polyamide fiber reinforced cement composites was found to be strongly affected by the tensile strength of the fibers.

• KIPS Transactions on Software and Data Engineering
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• v.1 no.1
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• pp.1-6
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• 2012

Web pages in a template-based web application (TWA) are automatically populated using a template shared by the pages with contents specific to the pages. So users can easily obtain information guided by a consistent structure of the template. Reduced duplicated code helps to increase the level of maintainability as well. However, TWA still has the interaction problem of classic web applications that each time a user clicks a hyperlink a new page is loaded, although a partial update of the page is desirable. This paper proposes a reengineering technique to transform the multi-page structure of legacy Java-based TWA to a single page one with partial page refresh. In this approach, hyperlinks in HTML code are refactored to AJAX-enabled event handlers to achieve the single page structure. In addition, JSP and Servlet code is transformed in order not to send data unnecessary for the partial update. The new single page consists of individual components that are updateable independently when interacting with a user. Therefore, our approach can improve interactivity and responsiveness towards a user while reducing CPU and network usage. The measurement of our technique applied to a typical TWA shows that our technique improves the response time of user requests over the TWA in the range from 1 to 87%.

• Journal of KIISE:Software and Applications
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• v.34 no.7
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• pp.635-645
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• 2007

Component technology has been widely accepted as an effective way for building software systems with reusable components, and Microsoft (MS) .NET is one of the recent representative component technologies. Model Driven Architecture (MDA) is a new development paradigm which generates software by transforming design models automatically and incrementally. Transformation of structural models in MDA has been successfully applied. However, transformation of dynamic models and pervasive services, such as transaction service, security service, synchronization service and object pooling are largely remains as an area for further research. The recent enterprise system has multi tier distributed architecture, and the functionality of early mentioned pervasive services is essential for this architecture. .NET platform can implement Component Object Model+ (COM+) component for supporting pervasive services by specify Attribute code. In this paper, we specify the functionalities of the COM+ component offering pervasive services, and then those functionalities are defined by UML profile. By using the profile, the Platform Specific Model (PSM) for .NET/C# is specified, and .NET components are automatically generated through our tool. The development productivity, extensibility, portability, and maintenance of software can be dramatically improved by using of the proposed methods.