• Steel and Composite Structures
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• v.21 no.6
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• pp.1307-1325
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• 2016

Nonlinear behavior of two-span, continuous composite steel-concrete girders strengthened with Carbon Fiber Reinforced Polymers (CFRP) bonded to the top of concrete slab over the negative moment region was evaluated using a non-linear Finite Element (FE) model in this paper. A three-dimensional FE model of continuous composite girder using commercial software ABAQUS simulated and validated with experimental results. The interfacial regions of the composite girder components were modeled using suitable interface elements. Validation of the proposed numerical model with experimental data confirmed the applicability of this model to predict the loading history, strain level for the different components and concrete-steel relative slip. The FE model captured the different modes of failure for the continuous composite girder either in the concrete slab or at the interfacial region between CFRP sheet and concrete slab. Through a parametric study, the thickness of CFRP sheet and shear connection required to develop full capacity of the continuous composite girder at negative moment zone have been investigated. The FE results showed that the proper thickness of CFRP sheet at negative moment region is a function of the adhesive strength and the positive moment capacity of the composite section. The shear connection required at the negative moment zone depends on CFRP sheet's tensile stress level at ultimate load.

• Geomechanics and Engineering
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• v.29 no.3
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• pp.301-310
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• 2022

Accurate prediction of mixed ground conditions ahead of a tunnel face is of vital importance for safe excavation using tunnel boring machines (TBMs). Previous studies have primarily focused on electrical resistivity surveys from the ground surface for geotechnical investigation. In this study, an FE (finite element) numerical model was developed to simulate electrical resistivity surveys for the prediction of risky mixed ground conditions in front of a tunnel face. The proposed FE model is validated by comparing with the apparent electrical resistivity values obtained from the analytical solution corresponding to a vertical fault on the ground surface (i.e., a simplified model). A series of parametric studies was performed with the FE model to analyze the effect of geological and sensor geometric conditions on the electrical resistivity survey. The parametric study revealed that the interface slope between two different ground formations affects the electrical resistivity measurements during TBM excavation. In addition, a large difference in electrical resistivity between two different ground formations represented the dramatic effect of the mixed ground conditions on the electrical resistivity values. The parametric studies of the electrode array showed that the proper selection of the electrode spacing and the location of the electrode array on the tunnel face of TBM is very important. Thus, it is concluded that the developed FE numerical model can successfully predict the presence of a mixed ground zone, which enables optimal management of potential risks.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1347-1356
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• 2015

Since 1970 transportation investment has been made rapidly, however the doubt on duplication and overinvestment of transportation facility also has been brought up. Thus the necessity for reasonable estimation of investment scale increases. In this paper various researches related to this subject are reviewed and categorized according to their methodologies, namely, the methodology using international comparison, trend of investment policy and endogenous economy development model. Based on these methodologies, AHP is applied to calculate proper investment scale. The result shows that the budget for satisfying the investment scale is estimated about 19.51~24.49 trillion won. This value is 4.28~9.26 trillion won higher than the proper investment budget established in National Fiscal Management Plan. In the future, it is necessary to establish systematic and efficient transportation investment plan by developing transportation policy model which can assess the economic feasibility, social equity and environmental soundness etc. at the same time.

• Journal of the Korea Institute of Building Construction
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• v.10 no.1
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• pp.81-89
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• 2010

Since 2004, the government has changedthe cost estimate system to one of an actual cost basis in order to calculate the optimum construction cost by reflecting changes in circumstance on the construction site in a timely manner. Currently, this is being applied to public construction work forover a billion won of actual cost data in estimation by contract unit cost. However, directly reflecting actual cost, which for large-sized construction work was originally an average unit cost, to a small building, entails the application of a low discount rate for the cost of materials, labor, etc. and therefore can frequently give rise to cases in which the actual cost of work performed exceeds the contract sum, which in turn causes problems such as decreased revenues, bad effectson business operation, productivity, etc. Therefore, to apply actual cost to small-sized construction work (less than a billion won), there should be a plan to modify unit cost in a manner that can reflect project scale, etc. in order to resolve the problem of unit cost application of actual cost to small-building construction projects. The unit cost modification model for proper actual construction cost in small-scale construction projects developed by this study will help to increase the relevant productivity and proper gain, preventing the aggravation of business operations. Organizations placing orders are also expected to be able to secure a more realistic construction cost in arranging the budget.

• Journal of Korean Society on Water Environment
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• v.35 no.3
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• pp.224-233
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• 2019

Nitrogen components in liquid manure can reduce safety and quality of environment harmfully. To minimize the environmental risks of manure, understanding fate of manure in environment is necessary. This study aimed at investigating applicability of a simplified Level III fugacity model for simulating $NH_3-N$ component to analyze environmental fate and transport of $NH_3-N$ in liquid manure and to provide basis for improving management of N in the liquid manure system and for minimizing the environmental impacts of N. The model simulation conducted for four environmental compartments (air, water, soil, and rice plants) during rice-cropping to trace $NH_3-N$ component and provided applicability of the Level III fugacity model in studying the environmental fate of $NH_3-N$ in manure. Most of $NH_3-N$ was found in water body and in rice plants depending upon the physicochemical properties and proper removal processes. For more precise model results, the model is needed to modify with the detailed removal processes in each compartment and to collect proper and accurate information for input parameters. Further study should be about simulations of various N-typed fertilizers to compare with the liquid manure based on a modified and relatively simplified Level III fugacity model.

• Journal of Ocean Engineering and Technology
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• v.22 no.3
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• pp.64-70
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• 2008

A full-scale field experiment is an important part in the design of ships and offshore structures. Full-scale tests in the ice-covered sea, however, are usually very expensive and difficult tasks. Model tests in a refrigerated ice tank may substitute this difficulty of full-scale field tests. One of the major tasks to perform proper model tests in an ice towing tank is to select a realistic material for model ice which shows correct similitude with natural sea ice. This study focuses on the testing material properties and the selection of model ice material which will be used in an ice model basin. The first Korean ice model basin will be constructed at the Maritime & Ocean Engineering Research Institute (MOERI) in 2009. With an application to the MOERI ice model basin, in this study the material properties of EG/AD/S model ice of IOT (Institute for Ocean Technology) Canada, were tested. Through comprehensive bending tests, the elastic modulus and the flexural strength of EG/AD/S model ice were evaluated and the results were compared with published test results from Canada. Instead of using an ice model basin, a cold room facility was used for making a model ice specimen. Since the cold room adopts a different freezing procedure to make model ice, the strength of the model ice specimen differs from the published test results. The reason for this difference is discussed and the future development for a making model ice is recommended.

• Geophysics and Geophysical Exploration
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• v.17 no.4
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• pp.242-246
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• 2014

Spectral induced polarization (SIP) is a useful technique, which uses electrochemical properties, for exploration of metallic sulfide minerals. Equivalent circuit analysis is commonly conducted to calculate IP parameters from SIP data. An equivalent circuit model, which indicates the SIP response of rock, has a non-uniqueness problem. For this reason, it is very important to select the proper model for accurate analysis. Thus, this study focused on suggesting a new model, which suitable for the analysis of an anomalous SIP response, such as ore. A suitability of the new model was verified by comparing it with the existing Dias model and Cole-Cole models. Analysis errors were represented as a normalized root mean square error (NRMSE). The analysis result using the Dias model was the NRMSE of 10.50% and was the NRMSE using the Cole-Cole model of 17.03%. Howerver, because the NRMSE of the new model is 0.87%, it is considered that the new model is more useful for analyzing the anomalous SIP data than other models.

• Journal of Internet Computing and Services
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• v.6 no.6
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• pp.57-69
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• 2005

This paper proposes a minimal workflow model as a feasible solution to the workflow process rediscovery problem. The minimal workflow model can be represented by the minimal workflow net. The process model is represented by ICN(Information Control Net) Modeling method, ICN can configure activity dependent net applying proper algorithm according to activity dependency among activities which configure the ICN, The proposed model is possible to develop with the application of minimal workflow net and with the application of the algorithm related to activity dependent net properties, Hence, it can solve the process rediscovery problem and can also be helpful on process improvement.

• Asia pacific journal of information systems
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• v.6 no.2
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• pp.201-220
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• 1996

The effects of information technology on people and society, while being profusely laid out in academic and popular literature, are largely anecdotal, fragmented, and speculative, not adding up to a consistent theory of IT impact. This is attributed to a lack of a proper research model that guides and integrates the research. This paper examines several dimensions of the IT impact research that characterize and distinguish the research and develops a conceptual model of the IT impact research. Three dimensions are examined - the search domain, the concept of organization, and the level of analysis. The dimensions are combined to produce several conceptual domains, each with differing issues and characteristics for research, that constitute the IT impact research. A model of the IT impact research is developed which proposes a series of transition among the search domains. At the end, the implications of the research model are discussed.

• Journal of Korean Academy of Nursing
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• v.46 no.5
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• pp.630-641
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• 2016

Purpose: This study was designed to construct a model which explains drug misuse behaviors in community-dwelling older adults. Methods: The design of this research is a cross-sectional study using structure equation modeling. The hypothetical model consisted of two types of variables: the exogenous variables of health status, cognitive ability, and negative emotion, and the endogenous variables of number of drugs, and drug misuse behaviors. The data collection was conducted from September 2 to September 21, 2013 through self-report questionnaires. Participants were 320 community-dwelling adults over the age of 65 living in J city. Data were analyzed with SPSS 21.0 program and Amos 18.0 program. Results: The results of the model fitness analysis were satisfied. The predictor variables for the hypothetical model explained 62.3% of variance regarding drug misuse behaviors. Drug misuse behaviors were directly affected by health status, cognitive ability, negative emotion and number of drugs and indirectly affected by health status, and negative emotion through number of drugs. Conclusion: These findings indicate factors that should be used in developing effective nursing interventions for safe and proper drug use and the prevention of drug misuse behaviors in community-dwelling older adults.