• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.4
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• pp.251-260
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• 2020

A growing interest has emerged in recycling used automobile batteries into energy storage systems (ESSs) to prevent their harmful effects to the environment from improper disposal and to recycle such resources. To transform used batteries into ESSs, composing battery modules with similar performance by grading them is crucial. Imbalance among battery modules degrades the performance of an entire system. Thus, the selection of modules with similar performance and remaining life is the first prerequisite in the reuse of used batteries. In this study, we develop an instrument to measure the impedance spectrum of a battery module to predict the useful remaining life of the used battery. The developed hardware and software are used to apply the AC perturbation to the used battery module and measure its impedance spectrum. The developed instrument can measure the impedance spectrum of the battery module from 0.1 Hz to 1 kHz and calculate the equivalent circuit parameters through curve fitting. The performance of the developed instrument is verified by comparing the measured impedance spectra with those obtained by a commercial equipment.

• The KIPS Transactions:PartD
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• v.14D no.3 s.113
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• pp.339-346
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• 2007

The objective of this study is to satisfy requirements for a variety of terminals to play wired web page contents in ubiquitous environment constantly connected to network. In other words, this study intended to automatically transcode wired web page into mobile web page in order to receive service by using mobile base to carry contents in Internet web page. To achieve this objective, we suggest the method that is to directly enter URL of web page in mobile device and to check contents of the current web page. For this, web page is converted into an image and configured into a mobile web page suitable for personal terminals. Users can obtain the effect of having web services provided by using computer with interfaces to expand, reduce and move the web page as desired. This is a caret unit play method, with which contents of web page are transcoded and played to suit each user According to the method proposed in this study, contents of wired web page can be played by using a mobile device. This study confirms that a single content can be serviced to suit users of various terminals. Through this, it will be able to reuse numerous wired web contents as mobile web contents.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.642-649
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• 2007

The effectiveness of add-on tertiary treatment processes for the polishing of the effluent of a biological nutrient removal (BNR) system from a modified $A^2/O$ process has been examined under the field condition with pilot-scale plants. The add-on treatment processes of 1) combined biofilm anoxic reactor and sand filtration, and 2) two-stage denitrification filter had been operated with various operating conditions. The experimental results indicated that two-stage denitrification filter could produced a better polished tertiary effluent. Filtration rate of $150m^3/m^2{\cdot}d$ for the 2-stage denitrifying filter could decrease the nitrate removal probably due to shorter detention time that caused insufficient reaction for denitrification. Two stage denitrification filter operated with M/N ratio of 3.0 and filtration rate of $100m^3/m^2{\cdot}d$ produced the tertiary effluent with nitrate and SS concentraitons of 2.8 mg/L and 2.3 mg/L, respectively. When the operating temperature reduced $30^{\circ}C$ to $18^{\circ}C$, $NO_3{^-}-N$ removal efficiency decreased from 73% to 68%.

• Journal of Communications and Networks
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• v.8 no.4
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• pp.451-460
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• 2006

Since low earth orbit (LEO) satellite constellations have important advantages over geosynchronous earth orbit (GEO) systems such as low propagation delay, low power requirements, and more efficient spectrum allocation due to frequency reuse between satellites and spotbeams, they are considered to be used to complement the existing terrestrial fixed and wireless networks in the evolving global mobile network. However, one of the major problems with LEO satellites is their higher speed relative to the terrestrial mobile terminals, which move at lower speeds but at more random directions. Therefore, handover management in LEO satellite networks becomes a very challenging task for supporting global mobile communication. Efficient and accurate methods are needed for LEO satellite handovers between the moving footprints. In this paper, we propose a new seamless handover management scheme for LEO satellites (SeaHO-LEO), which utilizes the handover management schemes aiming at decreasing latency, data loss, and handover blocking probability. We also present another interesting handover management model called satellite mobility pattern based handover management in LEO satellites (PatHO-LEO) which takes mobility pattern of both satellites and mobile terminals into account to minimize the handover messaging traffic. This is achieved by the newly introduced billboard manager which is used for location updates of mobile users and satellites. The billboard manager makes the proposed handover model much more flexible and easier than the current solutions, since it is a central server and supports the management of the whole system. To show the performance of the proposed algorithms, we run an extensive set of simulations both for the proposed algorithms and well known handover management methods as a baseline model. The simulation results show that the proposed algorithms are very promising for seamless handover in LEO satellites.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.12
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• pp.4835-4855
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• 2015

TV white space (TVWS) is showing promise to become the first widespread practical application of cognitive technology. In fact, regulators worldwide are beginning to allow access to the TV band for secondary users, on the provision that they access the geolocation database. Device-to-device (D2D) can improve the spectrum efficiency, but large-scale D2D communications that underlie TVWS may generate undesirable interference to TV receivers and cause severe mutual interference. In this paper, we use an established geolocation database to investigate the power allocation problem, in order to maximize the total sum throughput of D2D links in TVWS while guaranteeing the quality-of-service (QoS) requirement for both D2D links and TV receivers. Firstly, we formulate an optimization problem based on the system model, which is nonconvex and intractable. Secondly, we use an effective approach to convert the original problem into a series of convex problems and we solve these problems using interior point methods that have polynomial computational complexity. Additionally, we propose an iterative algorithm based on the barrier method to locate the optimal solution. Simulation results show that the proposed algorithm has strong performance with high approximation accuracy for both small and large dimensional problems, and it is superior to both the active set algorithm and genetic algorithm.

• Journal of Information Technology and Architecture
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• v.9 no.2
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• pp.187-197
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• 2012

The investment on informatization has caused the increase in complexity of IT resources as well as inefficiency of Information system management and redundant investment. Thus, the idea of EA (Enterprise Architecture) was developed in order to manage the IT resources efficiently but the systematical guideline was insufficiently provided in data area.. Because of this, it is necessary to make full use of DRM (Data Reference Model) so we can enhance the sharing and reuse of data between several institutions in public sector by extracting and managing data behind processes. In this study, we recognize the necessity of improvement on data classification which is highly utilized and present the direction for the data classification rethesis.

• Journal of KIISE:Software and Applications
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• v.36 no.7
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• pp.539-547
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• 2009

Software product line (SPL) engineering is an emerging paradigm for successful software reuse and has been adopted for various industrial and consumer products to improve their productivity and quality. However, most SPL methods require high initial costs and long development time, which makes many companies hesitate to adopt the SPL paradigm. In this paper we introduce a method to construct an SPL by extracting core assets from legacy components based on the feature model, which requires less initial time and effort. We also present a case study on cable set-top box software to illustrate the applicability of this method, and lessons learned that will provide guidelines for many companies to adopt the SPL paradigm.

• Journal of Korean Library and Information Science Society
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• v.48 no.1
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• pp.345-371
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• 2017

Traditionally, the construction industry field is one of the typical fields using facet analysis method. Internationally the facet analysis method is applied to the classification scheme "Uniclass" or thesaurus "Construction Industry Thesaurus(CIT)". In the case of Korea, the facet analysis method is being used in classification scheme "Construction Industry Classification System" but it is difficult to find studies on facet analysis method in thesaurus or building case study. This study aims to establish facet types by introducing building of thesaurus for information retrieval in construction field using facet analysis method and to suggest building plan of thesaurus in construction field using facet analysis method. In this paper, We establish the 11 top facets(agent/patient, artifacts, abstract, material, parts/component, works, attribute, media, process, space, time) and the 13 subfacet as rudimental facets and suggest building plan according to thesaurus building procedure which is suggested by International Standard(ISO 25964-1). The result of this study is expected to apply to facet based thesaurus. And it is also expected to reuse in Taxonomy or Ontology etc. and to use in interoperability with the classification scheme of Construction filed.

• The KIPS Transactions:PartD
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• v.13D no.4 s.107
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• pp.593-602
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• 2006

Software development methodology has been developed for satisfying goals of improvement in productivity and reduction in time-to-market through the reuse of software assets. The current methods that implement software product-line, one of software development methodologies, interfere massively with the core assets, which require high cost in assembly level reducing the effectiveness. In this paper, we introduce Aspect-Oriented Programming (AOP) as a method for improving assembly process in software product-line. The method that assembles core assets and variabilities is described by grammar elements such as Join point, pointcut and advice without code-change. We analyze requirements of a mini-system as an example adapting AOP and design using UML. Our study implements the variabilities, which are from design stage, using an Aspect-Oriented Programming Language, AspectJ and prove usability and practicality by implementing the proposed idea using an Aspect-Oriented Programming Language, AspectJ.

• The KIPS Transactions:PartD
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• v.12D no.7 s.103
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• pp.1001-1006
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• 2005

The Ministry of National Defense has developed MND-AF and Defense-CBD methodology to make the integration and management of standardization effective through enhancing the interoperability and reusability of information systems. Yet no explicit guidelines or procedures have not been developed for the applying range and mutual relationship of the artifacts between MND-AF and Defense-CBD methodology. Thus, the development time is unnecessarily extended and budget also is increasing because both methodologies produce the artifacts respectively. This paper presents a reusability enhancement scheme for producing MND-AF artifacts according to Defense-CBD process by analyzing artifacts of two methodology les at each element level, so that it will reduce the overhead of producing the artifacts and enhance the completeness of the artifacts. In result, in the case of applying Defense-CBD methodology for developing a information system34 artifacts out of 37 MND-AF artifacts can be reusable.