• Journal of Advanced Marine Engineering and Technology
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• v.38 no.5
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• pp.566-572
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• 2014

Recently, indoor navigation has been applied in large convention centers by using wireless sensor networks (WSNs), which provide not only a user's path to be traveled but also orientation and shopping information to increase user's convenience. This paper presents the localization system for estimating relative coordinates without pre-deployment of the reference node based on ultra wide band (UWB) ranging system, which is relatively suitable for indoor localization compared to other wireless communications, and azimuth sensor. The proposed localization system which consists of an azimuth sensor and a mobile node composed of three nodes estimates relative coordinates of the reference node without applying any recursive and time consumption algorithms. Also, in the process of estimating relative coordinates of the reference node, ranging errors are minimized through the proposed technique and the number of nodes can be reduced. Experimental results show the feasibility and validity of the proposed system.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.4
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• pp.175-185
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• 2002

In this paper, a new fully digital current control method of UPS inverter, which is based on an internal model control, is proposed. In the proposed control system, overshoots and oscillations due to the computation time-delay are compensated by explicit incorporation of the time-delay in the current control loop transfer function. The internal model controller is adopted to a second order deadbeat reference-to-output response which means that its response reaches the reference in two sampling time including computational time-delays. That is, the average current of filter capacitor is been exactly equal to the reference current with a time lag of two sampling intervals. Therefore, this method has an essentially overshoot free reference-to-output response with a minimum possible rise time. The effectiveness of the proposed control system has been verified by the simulation and experimental respectively. From the simulation and experimental results, the proposed system is achieved the robust characteristics to the calculation time delay and parameter variation as well as very fast dynamic performance, thus it can be effectively applied to the power supply for the critical load.

• Journal of Power Electronics
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• v.10 no.4
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• pp.412-418
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• 2010

This paper proposes a new algorithm to generate a reference signal for an active power filter using a sliding-window FFT operation to improve the steady-state performance of the active power filter. In the proposed algorithm the sliding-window FFT operation is applied to the load current to generate the reference value for the compensating current. The magnitude and phase-angle for each order of harmonics are respectively averaged for 14 periods. Furthermore, the phase-angle delay for each order of harmonics passing through the controller is corrected in advance to improve the compensation performance. The steady-state and transient performance of the proposed algorithm was verified through computer simulations and experimental work with a hardware prototype. A single-phase active power filter with the proposed algorithm can offer a reduction in THD from 75% to 4% when it is applied to a non-linear load composed of a diode bridge and a RC circuit. The active power filter with the proposed reference generation method shows accurate harmonic compensation performance compared with previously developed methods, in which the THD of source current is higher than 5%.

• Journal of Korean Library and Information Science Society
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• v.50 no.2
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• pp.215-235
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• 2019

Popularly known to be originated in museums and art galleries, curation is widely applied in many other fields ranging from curation commerce to curated databases by today. Libraries also have started to provide different types of curation services such as data curation, digital curation, content curation, book curation, and social curation. However, the relationship between the curation service and the library service is not adequately studied and documented. The objective of this paper is to address that gap by analyzing the relationship between curation service and the library service. Particularly, this paper pays attention to study the relationship between curation service and library reference service. The research methods used by this study were an extensive literature review followed by some carefully selected real-world examples of curation services in libraries and other fields. The authors have analyzed and documented the origin and the meaning of two concepts, the challenges faced by library reference service, and the applicability of curation as a modest form of library reference service in the $21^{st}$-century. Based on the study findings, this paper concludes that curation service is not a new concept for the library but a natural evolution of the library reference service in response to the changing information environment and user expectations in the digital age.

• The Journal of the Acoustical Society of Korea
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• v.40 no.1
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• pp.46-54
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• 2021

In this paper, active noise control was performed to reduce radiated noise in the low frequency band of dishwashers. First, through an analysis of the noise environment of the dishwasher, it was confirmed that the pump noise contributed the most to the radiated noise in the low frequency band, From the result of the noise environment analysis, the reference signal was selected to be the vibration signal of the pump body. The reference signal was obtained by using the accelerometer on the pump body, which can prevent acoustic feedback. The error signal sensor was selected as a microphone located at 1 m in front of the dishwasher and 0.5 m in height. And to design the controller, the error signal and the reference signal were measured at the operational rpms of the dishwasher at 2,500 rpm, 2,600 rpm and 2,800 rpm, and the secondary path transfer function was measured. The designed controller was mounted on Digital Signal Processor (DSP) equipment, and the control performance was verified experimentally. As a result of the measurement at the 3 operational rpms, the 7th multiple component of pump operating frequency decreased by 1.93 dB, 4.43 dB, 5.15 dB per rpm, and the 12th multiple component decreased by 6.67 dB, 2.34 dB, 4.28 dB per rpm. And overall Sound Pressure Level (SPL) decreased by 0.84 dB, 2.58 dB, 1.48 dB by rpm.

• Journal of Digital Convergence
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• v.10 no.5
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• pp.267-273
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• 2012

The semantic relationship structures hierarchically the huge amount of document objects which is usually not formatted. However, it is very difficult to structure relevant data from various distributed application domains. This paper proposed a new object management method to service the distributed domain objects by using semantic reference relationship. The proposed mechanism utilized the profile structure in order to extract the semantic similarity from application domain objects and utilized the joint matrix to decide the semantic relationship of the extracted objects. This paper performed the simulation to show the performance of the proposed method, and simulation results show that the proposed method has better retrieval performance than the existing text mining method and information extraction method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.1
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• pp.1-9
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• 2009

In this paper, proposed digital image watermarking technique with lifting wavelet transformation. This watermark technique can be easily extended in video content fields. Therefore, we apply this watermark technique to layered depth image structure that is efficient compression method of multi-view video with depth images. This application steps are very simple, because watermark is inserted only reference image. And watermarks of the other view images borrow from reference image. Each view image of multi-view video may be guaranteed authentication and copyright.

• Journal of Information Management
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• v.37 no.1
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• pp.57-81
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• 2006

The new service of Korean public library, ASK_a service model suggests a new management practice in collaborative digital reference services. The model has three functions: input transaction, process transaction, and output transaction. The best form for input is the web form. The best form for process is a model with a hybrid type of public libraries(hierarchical and lateral type). The output suggests the archiving policy for gathering the query-answer data. The core of this model is providing an advanced information service to its users through cooperation with public libraries and external manpower.

• Journal of Digital Contents Society
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• v.11 no.3
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• pp.399-406
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• 2010

This study deals with the proposition of the diversification strategy for participation contents service based on the open IPTV policy, and the strategic implication for IPTV players. This paper demonstrates implication for activation of participation contents to IPTV players with reference to differentiation of usages and needs to internet and television. Thus this paper proposes for diversification of player's competency (1) variety of production channels for contents, (2) enhanced accessibility, and (3) the strategic consistency for industrial eco-system. Moreover, this paper suggests that device differentiation for creation of demand, boosting customer satisfaction & immersion through closely interlocking contents.

• Journal of Korean Library and Information Science Society
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• v.40 no.4
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• pp.177-198
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• 2009

The domestic libraries offered users computer environment early to adapt in information age. However, the computer environment is generalized today, so it is needed to change about the role of electronic information room in this point. The author investigated use experience by 78 students who are student in library and information science. They experienced electronic information room and wrote their experience. As a result, they felt most inconvenience in information service of librarians, facilities and equipment and space. To improve the service of electronic information room, it is needed to develop the mission and service policy of electronic information room. And also the librarian must think the room as modern reference room that has digital and analog materials and information technology.