• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5301-5323
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• 2017

Small cell deployment offers a low-cost solution for the boosted traffic demand in heterogeneous cellular networks (HCNs). Besides improved spatial spectrum efficiency and energy efficiency, future HCNs are also featured with the trend of network architecture convergence and feasibility for flexible mobile applications. To achieve these goals, dual connectivity (DC) is playing a more and more important role to support control/user-plane splitting, which enables maintaining fixed control channel connections for reliability. In this paper, we develop a tractable framework for the downlink SINR analysis of DC assisted HCN. Based on stochastic geometry model, the data-control joint coverage probabilities under multi-frequency and single-frequency tiering are derived, which involve quick integrals and admit simple closed-forms in special cases. Monte Carlo simulations confirm the accuracy of the expressions. It is observed that the increase in mobility robustness of DC is at the price of control channel SINR degradation. This degradation severely worsens the joint coverage performance under single-frequency tiering, proving multi-frequency tiering a more feasible networking scheme to utilize the advantage of DC effectively. Moreover, the joint coverage probability can be maximized by adjusting the density ratio of small cell and macro cell eNBs under multi-frequency tiering, though changing cell association bias has little impact on the level of the maximal coverage performance.

• Journal of The Korean Digital Architecture Interior Association
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• v.12 no.4
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• pp.13-20
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• 2012

The recent advances in digital technology allow the use of BIM for integratively managing various information pertaining to an architectural structure. This can be the suitable tool for effectively utilizing the various requests of both the users and the administrators from the planning phase. In particular, planning and constructing a school facility can be challenging because it is an important learning facility where the students are required follow a set schedule. Accommodating to the various needs and requests of the users and the other related parties in the progress can be very difficult. Therefore, in order to use the BIM with the basis of data to manage the lifetime of the school facility, it is necessary to develop the specialized BIM process customized to the school facilities. Using this as the base, the BIM process specifically for school facilities should be phased in, applied, and expanded. The objective of this study is to define the scope of application and to plan for the efficient utilization of the BIM process specialized for school facilities, when conducting the project from planning phase to design development phase through the series of processes. Unlike the presently used enhancement of the visible minute details of the models, the methods to enhance the quality of information contained inside the model will be proposed. Also, the user will participate in the school facility construction. The realistic BIM application is aimed through the research for the processes for building models that will be utilized for construction and management.

• Journal of Digital Convergence
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• v.14 no.1
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• pp.379-386
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• 2016

This study explored Korean college students' smartphone game behavior for the pastime. Smartphone games have weakness that is not appropriate for playing the game because of small screen and non-sophisticated interface for operation. To defeat the disadvantage, the games employed minimalism like conciseness or simplicity. The study explored how conciseness influences perceived ease of use, perceived enjoyment, flow, and intent to use the game through PLS path modeling. We found that every hypothesis except a path, perceived ease of use to flow, proved significant. This result means that smartphone game design should consider the interface of users' convenience and user experience practically. Finally, based on the findings, suggestions for future studies were discussed.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.4
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• pp.441-454
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• 2008

Shipyard design and equipments layout problem, which are directly linked with the productivity of ship production, is an important issue serving as reference data of production plan for later massive production of ships. So far in many cases, design of a shipyard has been relying on the experienced engineers in shipbuilding, resulting in sporadic and poorly organized processes. And thus, economic losses as well as trials and errors in that accord have been pointed out as inevitable problems. This paper extracts a checklist of major elements to fine tune the shipbuilding yard designing process and the input/output data based on the simulation based shipbuilding yard layout designing framework and methodology proposed in existing researches, and executed initial architecture to develop software that integrates all the relevant processes and designing tools. In this course, both user request and design data by the steps are arranged and organized in the proposed layout design template form. In addition, simulation is done based on the parent shipbuilding process planning and scheduling data of the ship product, shipbuilding process and work stage facilities that constitute shipbuilding yard, and design items are verified and optimized with the layout and equipment list showing optimal process planning and scheduling effects. All the contents of this paper are based on simulation based shipbuilding yard layout designing methodology, and initial architecture processes are based on object oriented development methodology and system engineering methods.

• The Transactions of the Korea Information Processing Society
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• v.4 no.5
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• pp.1243-1256
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• 1997

Object modeling has been cinsidered as an efficient technique for eleciting user requirements and communicat-ing between developers and customers. But model itself is not easy to understand what recult will be after coding and whether it will be meet with the requirements of customers. In this paper, we developed the envuroment for visualization of object model for validating with rewuirnent at the early stage. Therefore, we defined correct and complete rules which can transform the object model.the delierables of Shler/Mellor's method, into a for-mal specification language of VDM(Vienna Development Methods) with a mathematical basis. This basis provides the means of proving that a specification is realizable and proving properties of a system.Therefore.the completeness, preciceness of object model can be verified by proving the transformed VDM specification and prototyping by constructing a visualization supporting enviroment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.147-154
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• 2015

Recently agile development process became increasing effectiveness, quality, attention to experts in customer satisfaction, as evidenced in this methodology when selecting projects promoting productive efficiency. With regard to contemporary needs and user requirements on the methodology selected to meet this paper is the product based Cross functional team suggested methodology Feature Team model to solve problems of this model, and organizing the Cross functional team, this team but this outcome (product) basis, were examined for the model that points to progress the development across multiple product as a functional unit, value-driven agile project through the Skills-based model and proposed a difference. And it examined the Agile Maturity metrics. PRINCE2 Agile Health-check entries future development direction of Agile techniques is a requirement of the project outset has studied the subject objective evaluation by the assumption that they can be changed at any time, not fixed this way and for the project team through research The proposed.

• The Journal of Korean Association of Computer Education
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• v.15 no.2
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• pp.57-66
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• 2012

It is the advantage of robot programming to improve the learners' interest. However, the drawback is existed in the fact that it is not easy to determine whether the problem lies in the hardware factor or programmed logic when an error takes place. This study is an attempt to develop a simulation tool which assists learners to concentrate on the problems not relating to robot assembling but to robot program. It aims to enable beginners make a sketch of their ideas and examine their logic through simulation. Therefore, an Etoys-based robot programming tool is developed to allows user to download and execute the simulated program into an assembled robot. The significance of this study is that easy activity of sketch-based simulation can support learners to understand how the principles of computer science are applied in daily life such as an automatic door system.

• Journal of Information Technology Applications and Management
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• v.20 no.4
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• pp.127-149
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• 2013

Competitiveness of service industry in Korea is relatively lower than OECD countries'. Korean government, therefore, has been trying to improve the competitiveness of service industry by accelerating information technology (IT) adoption. Even though most of factors of IT can be contributed to improve the financial performance, it may be affected differently among various industry types and life cycles of companies. Therefore, it is one of very important research issues to analyze the influential effect of IT considering industry types and organizational life cycles in service industries. The purpose of this study is to find out critical success factors of IT which influence financial performance considering different types and life cycles of service industries. We developed the model and identified key success factors of IT adoption as IT system quality, Information quality, IT maintenance, CEO support, IT education of organization, and IT competence of user. Additional analysis of moderating effect by organizational life-cycle and types of service industry are conducted. For data sampling 856 companies are participated and total 2,000 questionnaires are collected. Structural equation modeling method is conducted for statistical analysis. The results show that the model is valid and most of success factors of it are very useful for improving financial performance of service industries except organizational IT education. Moderating effect of industry types and organizational life cycles is valid but partially accepted. The results might be able to provide useful directions and guide lines of IT acceleration in service industries.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.8
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• pp.133-141
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• 2010

MG(Microgrid) is a small power supply system located on-site that can supply both the electricity and the hot-water simultaneously. Engineering S/W is requested to construct Microgrids economically. We developed Engineering S/W that can combine DERs (Distributed Energy Resources) most economically using the linear programming and estimate of the economic. Developed S/W was programed using GAMS(General Algebraic Modeling System) and it is composed of the optimal DER combination module and forecasting module of renewable energy's output. We embody it based on MS Excel considering the user's convenience and we show its validity through a case study. We think that developed S/W will be very useful for planning MGs and energy supply.

• The KIPS Transactions:PartD
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• v.9D no.1
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• pp.31-42
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• 2002

In this paper, we propose a new spatio-temporal representation scheme which can model moving objets trajectories effectively in video data and a new signature-based access method for moving objects trajectories which can support efficient retrieval on user query based on moving objects trajectories. The proposed spatio-temporal representation scheme supports content-based retrieval based on moving objects trajectories and concept-based retrieval based on concepts(semantics) which are acquired through the location information of moving objects trajectories. Also, compared with the sequential search, our signature-based access method can improve retrieval performance by reducing a large number of disk accesses because it access disk using only retrieved candidate signatures after it first scans all signatures and performs filtering before accessing the data file. Finally, we show the experimental results that proposed scheme is superior to the Li and Shan's scheme in terns of both retrieval effectiveness and efficiency.