• Journal of Science Education
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• v.33 no.2
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• pp.336-345
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• 2009

The purpose of this study is to analysis ERF components patterns of causal questions generated during the observation of biological phenomenon. First, the system that shows pictures causing causal questions based on biological phenomenon (evoked picture system) was developed in a way of cognitive psychology. The ERF patterns of causal questions based on time-series brain processing was observed using MEG. The evoked picture system was developed by R&D method consisting of scientific education experts and researchers. Tasks were classified into animal (A), microbe (M), and plant (P) tasks according to biological species and into interaction (I), all (A), and part (P) based on the interaction between different species. According to the collaboration with MEG team in the hospital of Seoul National University, the paradigm of MEG task was developed. MEG data about the generation of scientific questions in 5 female graduate student were collected. For examining the unique characteristic of causal question, MEG ERF components were analyzed. As a result, total 100 pictures were produced by evoked picture and 4 ERF components, M1(100~130ms), M2(220~280ms), M3(320~390ms), M4(460~520ms). The present study could guide personalized teaching-learning method through the application and development of scientific question learning program.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.6
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• pp.751-760
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• 2021

Most bridges in Korea are over 20 years old, and many problems linked to their deterioration are being reported. The current practice for bridge inspection mainly depends on expert evaluation, which can be subjective. Recent studies have introduced data-driven methods using building information modeling, which can be more efficient and objective, but these methods require manual procedures that consume time and money. To overcome this, this study developed an image-based automaticbridge component classification network to reduce the time and cost required for converting the visual information of bridges to a digital model. The proposed method comprises two convolutional neural networks. The first network estimates the type of the bridge based on the superstructure, and the second network classifies the bridge components. In avalidation test, the proposed system automatically classified the components of 461 bridge images with 96.6 % of accuracy. The proposed approach is expected to contribute toward current bridge maintenance practice.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.593-602
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• 2011

The estuarine area of the ecological environment had been seriously damaged by reckless developments during the past half century. The demand for management in estuarine area increased but the efficient management system did not exist. Therefore the aim of this study is to develop a GIS-based integrated DB management system by integrating the ecological environmental data of each division in estuarine area. To achieve this, the system used integrated DB. It is classified into a surveyed monitoring DB in 2010 at estuarine area of Yeongsan and GIS DB to express the spatial data. The integrated DB management system was developed using VisualBasic.NET languages and Arcobjects component for Map-based spatial analysis. Also, to improve the utilization of data, the composition of GUI(Graphical User Interface) through user needs analysis, the expression of monitoring DB, the priority of layer and the function for modular unit were defined. Ultimately the system was developed based on the defined items. GIS-based integrated DB management system can support to understand the ecological environment in estuarine area of Yeongsan river. Also it will provide the users with effective sharing and environmental management of the data. In the future study, comprehensive diagnosis for ecological environment in estuarine area and the reliable prediction need to be made by connecting modeling system.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1934-1944
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• 2017

As a key component of high-voltage power conversion system for electric vehicles (EVs), bidirectional DC/DC (Bi-DC/DC) is required to have high efficiency and light weight. Conventional design methods optimize the Bi-DC/DC at the maximum power dissipation point (MPDP). For EVs application, the work condition of the Bi-DC/DC is not strict as the MPDP, where the design method using MPDP may not be optimal during travel of EVs. This paper optimizes the Bi-DC/DC converter targeting efficiency and weight based on the driving cycle. By analyzing the two-phase interleaved Bi-DC/DC for hybrid energy storage systems (HESS) of EVs, its power dissipation is calculated, and an efficiency model is derived. On this basis, weight models of capacitor, inductor and heat sink are built, as well as a dynamic temperature model of heat sink. Based on these models, a method using New European Driving Cycle (NEDC) for optimal design of Bi-DC/DC which simultaneously considered efficiency and weight is proposed. The simulation result shows that compare with conventional optimization methods revealed that the optimization approach based on driving cycle allowed significant weight reduction while meeting the efficiency requirements.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.2
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• pp.123-137
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• 2014

The aviation gas turbine is composed of many expensive and highly precise parts and operated in high pressure and temperature gas. When breakdown or performance deterioration occurs due to the hostile environment and component degradation, it severely influences the aircraft operation. Recently to minimize this problem the third generation of predictive maintenance known as condition based maintenance has been developed. This method not only monitors the engine condition and diagnoses the engine faults but also gives proper maintenance advice. Therefore it can maximize the availability and minimize the maintenance cost. The advanced gas turbine health monitoring method is classified into model based diagnosis (such as observers, parity equations, parameter estimation and Gas Path Analysis (GPA)) and soft computing diagnosis (such as expert system, fuzzy logic, Neural Networks (NNs) and Genetic Algorithms (GA)). The overview shows an introduction, advantages, and disadvantages of each advanced engine health monitoring method. In addition, some practical gas turbine health monitoring application examples using the GPA methods and the artificial intelligent methods including fuzzy logic, NNs and GA developed by the author are presented.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.662-669
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• 2016

In this work, nonlinear control of a three-phase shunt active power filter (SAPF) has been studied and compared to classical control based on proportional integral regulator. The control strategy is based on the direct current method using sliding mode control (SMC), where the aim is to regulate the average voltage across the dc bus of the inverter. Details are given for the control algorithm; the controller is comprised of a current loop which utilizes a hysteresis controller to generate the gating signals for the switching devices, and a nonlinear controller based on SMC law which is different from classical laws based on error between reference and measured output voltage of the inverter. Sliding surface applied in this work contains the whole of state variables, in order to ensure full control of the system behavior in the presence of disturbances that affect the supply source, the load parameters or the reference value. The designed controller offers advantage that it can gives the improvement of dynamic and static performances in cases of large disturbances. A comparison of the effects of PI control and SMC on the APF response in steady stat, under line variations, load variations, and different component variations is performed.

• Journal of Construction Engineering and Project Management
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• v.2 no.4
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• pp.11-19
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• 2012

Construction supply chain management (CSCM) has become one of the critical factors that determine the success of a construction project as it becomes increasingly complicated and mega-sized. Particularly for high-rise or mega-sized building construction, just-in-time supply chain management is required due to lack of storage space and effective logistics for construction components and materials at a construction site. Despite the fact that research and development of radio frequency identification (RFID) and wireless sensor network (WSN) technology have been performed, construction project managers still need to carry mobile devices and check material and component flow at each stage of the supply chain process. This research proposes that the equipment used in the construction supply chain process, such as movers, trailers, gates, and hoists, can become main actors in the supply chain process using RFID and WSN technologies. And the proposed equipment and process focused on a solution to the redundancy identification problem, which has been observed in operations that use RFID/WSN-based processes for construction logistics. This paper also presents issues identified through verification and validation of the research results and proposes further studies.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.4
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• pp.117-124
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• 2000

This paper presents a design of urban waterfront park using agricultural reservoir in urban fringe area to meet increasing leisure demand for urban resident and to improve resident's quality of life through preventing the reservoir from urban use after reclamation. The site, Unam-Ji, is located on northern part of Taegu metropolitan area, having 17,791 square meters. We had designed this park from 1997 to 1998. After analyzed such factor as accessibility, current land uses, topography, hydrology, vegetation and landscape, climate, and soil, we constructed basic design scheme and principes such as conservation of natural resources, meeting user's recreation demands, providing opportunities for experiencing natural process, integrating naturalness and amenity of the site, and comfortable place with natural dynamism. Based on these principles, we have designed Unam-Ji waterfront park having intrinsic characteristics of the site, maintaining water quality and ecological restoration and improving water-based recreation opportunities. After evaluation of such criteria of design alternative as land use and circulation, spatial organization, convenience for use of and maintenance, conservation of natural environment, and degree of achieving planning and design goals, and maintaining landscape, we have visualized and formalized waterfront park in design process, which is consisted of four squares-- green square for multiple uses, water-based recreation square, pedestrian roads and decks near waterfront, performance square and fords near waterfront. In conclusion, this waterfront park design contributes to improve quality of urban development through preserving agricultural as an important component of urban water system and provide important planning and design implications in urban open space planning.

• Journal of Power Electronics
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• v.13 no.4
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• pp.656-668
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• 2013

This paper presents a wavelet-fuzzy based controller for indirect field oriented control of three-phase induction motor drives. The discrete wavelet transform is used to decompose the error between the actual speed and the command speed of the induction motor drive into different frequency components. The transformed error coefficients along with the scaling gains are used for generating the control component of the motor. Self-tuning fuzzy logic is used for online tuning of the scaling gains of the controller. The proposed controller has the ability to meet the speed tracking requirements in the closed loop system. The complete indirect field oriented control scheme incorporating the proposed wavelet-fuzzy based controller is investigated theoretically and simulated under various dynamic operating conditions. The simulation results are compared with a conventional proportional integral controller and a fuzzy based controller. The speed control scheme incorporating the proposed controller is implemented in real time using a digital processor control board. Simulation and experimental results validate the effectiveness of the proposed controller.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.6
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• pp.630-640
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• 2001

In this paper, we describe the design and implementation of ObjectPeerWork, which is a framework for the development of shared object model-based P2P(Peer-to-Peer) applications. The shared object model can prevent the computing power decrease on the way of resource management by incorporating the resource management function into resources themselves, and raise reliability on shared resources by improving the security problems. Also this model assures expandability by means of distributed component-based request broker manager and module container. The ObjectPeerWork based on this shared object model is a framework which makes the implementation of the enterprise information system possible, and makes distribution of the computing power and efficient resource management possible by improving the weakness in the general P2P model.