• Wind and Structures
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• v.21 no.6
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• pp.693-707
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• 2015

The efficiency of wind turbines (WT) is primarily reflected in their ability to generate electricity at any time. Downtimes of WTs due to "conventional" inspections are cost-intensive and undesirable for investors. For this reason, there is a need for structural health monitoring (SHM) systems, to enable service and maintenance on demand and to increase the inspection intervals. In general, monitoring increases the cost effectiveness of WTs. This publication concentrates on the application of two vibration-based SHM algorithms for stability and structural change monitoring of offshore WTs. Only data driven, output-only algorithms based on stochastic subspace identification (SSI) in time domain are considered. The centerpiece of this paper deals with the rough mathematical description of the dynamic behavior of offshore WTs and with the basic presentation of stochastic subspace-based algorithms and their application to these structures. Due to the early stage of the industrial application of SHM on offshore WT on the one side and the required confidentiality to the plant manufacturer and operator on the other side, up to now it is not possible to analyze different isolated structural damages resp. changes in a systematic manner, directly by means of in-situ measurement and to make these "acknowledgements" publicly available. For this reason, the sensitivity of the methods for monitoring purposes are demonstrated through their application on long time measurements from a 1:10 large scale test rig of an offshore WT under different conditions: undamaged, different levels of loosened bolt connections between tower parts, different levels of fouling, scouring and structure inclination. The limitation and further requirements for the approaches and their applicability on real foundations are discussed along the paper.

• Journal of KIISE:Software and Applications
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• v.32 no.8
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• pp.717-729
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• 2005

Product Line Engineering (PLE) consists of two phases; Core Assets Development and Application Engineering. The core asset development is to model common features of members in a domain and to develop them. The application engineering is to effectively generate an application by instantiating the core asset. Today, PLE research mainly focuses on developing core assets, whereas activities and instructions for application engineering are weakly defined. Moreover, instructions of application engineering are not enough to be practically applied. To widely apply PLE to industry, researches on systematic and practical methods such as instantiation processes, instructions, and artifacts are needed. In this paper, we propose a practical PLE process, instructions, and artifacts about each activity. And then, we also present a case study to show applicability and practicality of the process proposed in this paper.

• Journal of Korea Multimedia Society
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• v.14 no.11
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• pp.1450-1457
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• 2011

Currently most of leak detection monitoring systems use digital maps with paying royalties, and this increases the cost of system construction and financial burdens on local self-governing bodies that manage such systems. Moreover, they have inefficiencies in repair and maintenance, functional expansion, and compatibility with other systems. Thus, this study developed a waterworks pipe network monitoring system that pursues low cost and high efficiency using general-purpose maps on the Internet such as google maps. As this system uses highly compatible free maps, it costs less in construction and its hardware requirements are lower than existing systems, and consequently, overall monitoring performance is enhanced and the cost of construction goes down sharply. This study also proposed a method for pipeline DB construction, which can be started together with the construction of the monitoring system, in order to improve the field applicability of the system.

• Journal of the Korean Geotechnical Society
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• v.32 no.4
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• pp.51-61
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• 2016

In this study, a new TDR system equipped with a flat type probe has been developed to improve the currently used TDR system that measures dry density and water content. To verify the developed TDR system, TDR tests were conducted on Jumunjin sand and three typical soils. Also, additional tests were performed to measure the correction value of the developed probe. Using the TDR signals, dielectric constant, electrical conductivity and soil constants were derived. The water content and dry density of the soils were determined through the TDR tests. The applicability of the TDR system was examined by comparison of the measured values by TDR and the real values. The values of dry density and water content were found to have about 2% and 0.5% error, respectively. Based on the test results, it has been confirmed that the new TDR system can be used as an alternative to the previous TDR system as it can measure the dry density and the water content with reasonable accuracy, leading to significant time and cost savings.

• Journal of the Korea Institute of Building Construction
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• v.14 no.6
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• pp.597-604
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• 2014

In order to match the paradigm shift of a construction company for obtaining competitive edge, it is necessary to introduce newly an innovative educational method in the architectural engineering domain. The objective of this study is to adopt team-based learning, whose effectiveness have been proven in other domains, and to examine its applicability in architectural engineering education. To verify its effectiveness, a questionnaire survey of 39 attendees was conducted at the end of a term. As a result of that, academic achievement of students was higher than that of previous teaching method. In the future, team-based learning adopted in more subjects of the architectural engineering will contribute to improve the academic achievement of students by extension, to raise up the competent practitioners.

• Korean Institute of Interior Design Journal
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• v.13 no.5
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• pp.106-113
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• 2004

The purpose of this study is to present the dwelling space by attaching or inserting the mobile space unit to the fixed building by providing the temporary dwelling space for those suffering from flood disaster, natural disaster or solitary old people or the space and program that the completed building in the city can not provide such as temporary events in the bridge, passage space, walking space for the handicapped, stores located between street blocks, and plaza. Therefore, this study was intended to investigate temporary dwelling space through the composition of space and the experiment of the applicability of the program through the methods of movement, folding, module, expansion and evolution of mobile space. An attempt was made to apply the concept of ‘mobile space’ to the dwelling space not only with a focus on the freedom of variable and changeable physical movement but also with a focus on the existence of the nomad and the way of thinking that bleaks away from a given value system and code, creates a new value and continues to move to a new domain. This study attempted to analyze how the concept of ‘mobile space’ has been developed in what form and method they have been applied and interpreted in the historical background. It attempted to resolve the concepts of movement and mobility through the experiment so that they might apply to the space of contemporary city. This study attempted to experiment this possibility using the mobile space unit and apply it.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.855-862
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• 2013

A series of 1/5 scale-down reactor flow distribution tests had been conducted to determine the hydraulic characteristics of an APR+ (Advanced Power Reactor Plus), which were used as the input data for an open core thermal margin analysis code. In this study, to examine the applicability of computational fluid dynamics with the porous model to the analysis of APR+ internal flow, simulations were conducted using the commercial multi-purpose computational fluid dynamics software ANSYS CFX V.14. It was concluded that the porous domain approach for some reactor internal structures could adequately predict the flow characteristics inside a reactor in a qualitative manner. If sufficient computational resources are available, the predicted core inlet flow distribution is expected to be more accurate by considering the real geometry of the internal structures, especially upstream of the core inlet.

• Structural Engineering and Mechanics
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• v.65 no.3
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• pp.291-302
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• 2018

Rigid body spring method (RBSM) is an effective tool to simulate the cracking process of structures, and has been successfully applied to investigate the behavior of reinforced concrete (RC) members. However, the theoretical researches and engineering applications of this method mainly focus on two-dimensional problems as yet, which greatly limits its applications in actual engineering projects. In this study, a three-dimensional (3-D) RBSM for RC structures is proposed. In the proposed model, concrete, reinforcing steels, and their interfaces are represented as discrete entities. Concrete is partitioned into a collection of rigid blocks and a uniform distribution of normal and tangential springs is defined along their boundaries to reflect its material properties. Reinforcement is modeled as a series of bar elements which can be freely positioned in the structural domain and irrespective of the mesh geometry of concrete. The bond-slip characteristics between reinforcing steel and concrete are also considered by introducing special linkage elements. The applicability and effectiveness of the proposed method is firstly confirmed by an elastic T-shape beam, and then it is applied to analyze the failure processes of a Z-type component under direct shear loading and a RC beam under two-point loading.

• 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 Academy of Nursing
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• v.46 no.2
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• pp.293-304
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• 2016

Purpose: This methodological study was conducted to develop and psychometrically test the Transcultural Self-efficacy scale (TCSE-scale) for nurses. Methods: Initial 41 items for the TCSE-scale were generated based on extensive literature reviews and in-depth interviews with 18 nurses who had experience in caring for foreign patients. Cultural Competence and Confidence model was used as a conceptual framework. Content validity was evaluated by an expert panel. Psychometric testing was performed with a convenience sample of 242 nurses recruited from four general hospitals in the Seoul metropolitan area and Gyeonggi-do province of South Korea. To evaluate the reliability of TCSE-scale, a test-retest reliability and an internal consistency reliability were analyzed. Construct validity, concurrent validity, criterion validity, convergent validity and discriminative validity were used to evaluate the validity. Results: The 25-item TCSE-scale was found to have three subscales-Cognitive, Practical, and Affective domain-explaining 91.5% of the total variance. TCSE-scale also demonstrated a concurrent validity with the Cultural Competence Scale. Criterion-related validity was supported by known-group comparison. Reliability analysis showed an acceptable-to-high Cronbach's alpha-.88 in total, and subscales ranged from .76 to .87. The ICC was .90, indicating that the TCSE-scale has internal consistency and stability of reliability. Conclusion: This preliminary evaluation of the psychometric scale properties demonstrated an acceptable validity and reliability. The TCSE-scale is able to contribute to building up empirical and evidence based on data collection regarding the transcultural self-efficacy of clinical nurses. We suggest further testing of the applicability of TCSE-scale in different settings and community contexts.