• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.752-755
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• 2001

In order to investigate the vibration characteristics of fluid-structure interaction problem, we modeled two rectangular identical plates coupled with bounded fluid. The fixed boundary condition along the plate edges and an ideal fluid are assumed. MSC/NASTRAN was used to perform finite element analysis and analytic solutions were compared with experimental solutions to verify finite element model. As a result, comparison of FEM and experiment show good agreement, and the transverse vibration modes, in-phase and out of-phase, were observed alternately in the fluid-coupled system. The effect of distance between two rectangular plates on the fluid-coupled natural frequency is investigated.

• Interaction and multiscale mechanics
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• v.3 no.4
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• pp.389-403
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• 2010

Based on the Model Coupled Method (MCM), a case study has been carried out on a Concrete-Filled Steel Tubular (CFST) tied arch bridge to investigate the vibration problem. The mathematical model assumed a finite element representation of the bridge together with beam, shell, and link elements, and the vehicle simulation employed a three dimensional linear vehicle model with seven independent degrees-of-freedom. A well-known power spectral density of road pavement profiles defined the road surface roughness for Perfect, Good and Poor roads respectively. In virtue of a home-code program, the dynamic interaction between the bridge and vehicle model was simulated, and the dynamic amplification factors were computed for displacement and internal force. The impact effects of the vehicle on different bridge members and the influencing factors were studied. Meanwhile the acceleration responses of some of the components were analyzed in the frequency domain. From the results some valuable conclusions have been drawn.

• Child Health Nursing Research
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• v.10 no.1
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• pp.48-58
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• 2004

Purpose: Internet addiction is a newly recognized problem in the adolescents. The purpose of this study was to identify and analyze the educational needs for Internet addiction in middle school students of Korea. Method: The subjects of this study were 450 middle school students. The data were collected from open and structured questionnaire about the educational needs for Internet addiction. Result: As a result of content analysis of educational needs for Internet addiction, 9 domains and 19 themes were categorized from 542 statements. 9 Domains are : Definition, Etiology, Status, Process, Diagnosis, Influence, Coping and Prevention of Internet Addiction and General Information of Internet Use. These results were revealed that middle school students had comprehensive education needs for Internet Addiction. Also, there were the difference of need contents and frequency between school boy and girl students. Most of students had high educational needs for Internet addiction based on school health care program. Conclusion: It would be necessary to develop on Internet addiction prevention program for adolescents concerning these findings. In the future, there should be study to identify the psychological characteristics of adolescent associated with Internet addiction.

• International Journal of Ocean System Engineering
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• v.1 no.2
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• pp.89-94
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• 2011

Underwater localization is a crucial capability for reliable operation of various types of underwater vehicles including submarines and underwater robots. However, sea water is almost impermeable to high-frequency electromagnetic waves, and thus absolute position fixes from Global Positioning System (GPS) are not available in the water. The use of acoustic telemetry systems such as Long Baseline (LBL) is a practical option for underwater localization. However, this telemetry network system needs to be pre-deployed and its availability cannot always be assumed. This study focuses on demonstrating the validity of terrain-based localization techniques in a GPS-denied underwater environment. Since terrain-based localization leads to a nonlinear estimation problem, nonlinear filtering methods are required to be employed. The extended Kalman filter (EKF) which is a widely used nonlinear filtering algorithm often shows limited performance under large initial uncertainty. The feasibility of using a particle filter is investigated, which can improve the performance and reliability of the terrain-based localization.

• Journal of Construction Engineering and Project Management
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• v.7 no.1
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• pp.1-12
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• 2017

Construction delay is one of the basic constrains to achieve the project objectives in developing countries. This study aims to find the causes and effects of construction delays in developing countries. A thorough literature review has been done following the content analysis method. The relevant literature of 28 developing countries was collected from the scholarly journals published in the period of 2006 to 2016. The different developing countries are grouped into three geographic regions, i.e. South and Southeast Asia, Middle East, and Africa. In these regions, total 53 potential causes of delay under 8 major groups are identified. Frequency and ranking of these factors have been done. The factors, delay in progress payment by owner, contractors' cash flow problem, improper planning and scheduling, poor site management, and change order by owner during construction, are acknowledged as critical causes of delay in developing countries. This study will assist both academic and professional experts providing more insight about the construction delays and project management in developing countries.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.2
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• pp.11-18
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• 1995

The goal of this research is to get a measuring system for absorption characteristics of electromagnetic wave absorbers in fernite type which are flat, grid-type and special type, etc. It is, however, very difficult to measure the absorption characteristics in as low frequency as 30 MHz. To solve the problem, therefore, we propose a standing wave method and a measurement method in time domain using paralledl striplines, construct the measuring system, and measure the charac- teristics of ferrite microwave absorbers in grid type using the proposed measuring system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.277-286
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• 2010

In this paper we analyse radiation measurement method for UWB wireless system of the wideband low power frequency characteristics. In the radiation measurement environment we discuss RMS electric field strength, UWB PSD, UWB detect signal level, UWB noise signal collection etc.. also, we discuss power measure method of the CISPR16-1, low level e.i.r.p radiation measurement method. lastly we analyse consideration problem for the signal analyser of the UWB system.

• The Journal of Information Systems
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• v.18 no.3
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• pp.71-88
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• 2009

Recently, RFID(Radio Frequency IDentification) has emerged as the main technology in the logistic services. When the existing recognition technology based on bar codes brings about lots of problem due its own limits. RFID becomes the center of attention to solve them. However, RFID is not without any obstacles : companies have their own operating systems. while RFID is developed regardless of each campany's special features. RFID middleware system based on web service is expected to remove these obstacles. This paper shows how to operate the middleware based on web service and to lay in the DB the tag informations taken from reader system Middle assures that companies adopting RFID system for their logistic service are given athptabwebty to any systems whatsoever, avaweable by way of defining logistic information, tag information and reader information. For this purse, we implement as the basic web service a middleware system that turns all data into XML(eXtensatle Markupmsngunfo) of SOAP(Simple Object Access Protocol), the standard data.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.8
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• pp.1811-1816
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• 2012

Black marker cause unnatural problems between the existing various contents and marker. To solve this problem, we tested frequency of 3D objects according to the various colors and color placement. Based on this, infant's learning content system based NyARToolkit for the mobile-based augmented reality was implemented. By insert to color marker, We are solved the unnatural problems in the Implemented system. and infant can study seamlessly because concentration increases by the familiar character on the markers.

• Korean Journal of Child Studies
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• v.19 no.2
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• pp.65-75
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• 1998

This study investigated the relationships between the child-rearing involvement of fathers and their children's social-emotional competence. The subjects were 257 kindergarten children and their fathers. Data on the children's social and emotional competence were provided by their mothers, kindergarten teachers and five trained observers. The observers tested the social-emotional problem solving ability of the children. The data were analyzed by frequency, percentage, mean, t-test, one-way ANOVA, Scheffe post test, and Pearson's correlations. Results showed child rearing involvement differences between fathers based on (1) age and educational level of fathers, and (2) sex of child. Father's child-rearing involvement and child's social-emotional competence were correlated, especially in children whose fathers participated positively in child-rearing and had effective cognitive strategies for solving social and emotional problems.