• Journal of Korea Water Resources Association
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• v.41 no.8
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• pp.761-772
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• 2008

The object of this study is to develop the model that solves the numerically difficult problems in hydraulic engineering and to demonstrate the applicability of this model by means of various test examples, such as, verification in the gradually varied unsteady condition, three steady flow problems with the change of bottom slope with exact solution, and frictional bed with analytical solution. The governing equation of this model is the integral form of the Saint-Venant equation satisfying the conservation laws, and finite volume method with the Riemann solver is used. The evaluation of the mass and momentum flux with the HLL Riemann approximate solver is executed. MUSCL-Hancock scheme is used to achieve the second order accuracy in space and time. This study introduce the new and simple technique to discretize the source terms of gravity and hydrostatic pressure force due to longitudinal width variation for the balance of quantity between nonlinear flux and source terms. The results show that the developed model's implementation is accurate, robust and highly stable in various flow conditions with source terms, and this model is reliable for one-dimensional applications in hydraulic engineering.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2A
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• pp.85-95
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• 2012

This paper presents an investigation on the ultimate behavior of steel cable-stayed bridges using nonlinear finite element analysis method. Cable-stayed bridges exhibit various geometric nonlinearities as well as material nonlinearities, so rational nonlinear finite element analysis should be performed for investigation of the ultimate behavior. In this study, ultimate behavior of steel cable-stayed bridges was studied using rational ultimate analysis method. Nonlinear equivalent truss element and nonlinear frame element were used for modeling the cable, girder and mast. Moreover, refined plastic hinge method was adopted for considering the material nonlinearity of steel members. In this study, the 2-step analysis method was used. Before live load analysis, initial shape analysis was performed in order to consider the dead load condition. For investigation of the ultimate behavior of steel cable-stayed bridges, analysis models which span length is 920.0 m were used. Radiating type and fan type were considered as the cable-arrangement types. With various quantitative evidences such as load-displacement curves, deformed shapes, locations of the yield point or region, bending moment distribution and so on, the ultimate behavior of steel cable-stayed bridges was investigated and described in this paper.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.349-356
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• 2018

This paper attempts to develop a connection model based on FE analysis that can be applied to the evaluation of earthquake fragility of Steel Storage Racks lacking research in Korea. In order to accomplish this goal, shaking table tests, modal tests, and various member tests (8 case, push-over test) for structural members have been conducted to understand the behavior of steel storage racks. Based on the experimental results, detailed modeling of the joints was conducted using the NX-Nastran program in order to develop a connection model for Steel storage racks to be applied to the seismic vulnerability assessment. Especially, surface to surface contact element and spring element are applied to simulate the connection between the column member and the beam member connected by the simple latch method. Spring element model developed and applied ARX (Auto Regressive eXogenous) based mathematical model. The simulation results based on the FE model showed excellent reliability with a mutual error rate of less than 8% when compared with the member test results. As a result, it was confirmed that the FE model based connection model developed in the study can be applied to the analytical model for the seismic vulnerability assessment of Steel storage racks.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.151-162
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• 2012

It is not surprising to hear news about irresistible natural disasters all over the world due to climate change. Korean Government has focused on developing a variety of green technologies to reduce green house gasses, in particular, carbon dioxide. This study suggested 18 technology divisions for achieving green highway technology development in six different sub-sectors considering life-cycle of roadway and surveyed 29 highway and/or transportation professionals of three institutes using AHP(Analytical Hierarchy Process) analysis to construct "Green Highway"and realize carbon emission reductions and energy use efficiency in a road sector in Korea. Expert Choice Software was used to rank 18 technology divisions weighted by two-level choices. Transport Operating Infrastructure Improvement, Roadway Policy Implementation, Green Transportation(such as Pedestrian and Bicycle) were highly ranked by respondents according to results of the AHP modeling. Among the 18 divisions, technology policy for supporting R&D investments from development to commercialization was ranked as the most significant one to be focused. Green Transportation Facility Design/Construction/Operation and Eco-Friendly Roadway Plan were followed as expected since professionals have thought that the planning/design step of the life-cycle is a starting point to reduce carbon dioxide from roads more and more. Additionally, comparing the results with the Government investment trend 2006-2011 for the roads, it can be interpreted that the Government should invest to the R&D area more widely than before to promote element and core technology development for Green Highway Construction. Above all, small and mid-sized businesses have to be invested as well as encouraged to undertake green highwayrelated objects to accomplish the divisions which ranked high.

• Journal of Korean Society of Steel Construction
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• v.21 no.1
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• pp.63-70
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• 2009

Failure modes result in fracture or tearing, which may cause deterioration of resistance and reduction of inelastic deformation capacity. The potential failure modes for Special Concentrically Braced Frames (SCBFs) include fracture or tearing of the brace, net section fracture of the brace or gusset plate, fracture of the gusset plate welds, shear fracture of the bolts, block shear, excessive bolt bearing deformation, and buckling of the gusset plate. HSS tubular braces are commonly used in SCBFs, and net section fracture of the tubular brace may also occur through the brace net section at the end of the slot cut into the tube to slip over the gusset plate. This failure mode is categorized as a tension failure mode, and may cause dramatic loss of resistance and brittle behavior. Net section reinforcement is required according to AISC design specifications (AISC 2001). In this paper, the need to reinforce the net section area was discussed. Initially, the results of the net section fracture tests done by the University of California in Berkeley were presented with the modeling of these tests using FE models. To investigate the possibility of net section fracture in an actual frame, the slot end hole model was adapted to the frame FE model, and alternate near-fault histories were applied with tension-dominated cycles, since previous analyses showed that loading history was the most critical factor in net section fracture. The need for this reinforcement (cover plate) and the tension-dominated near-fault history were investigated.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.4 s.74
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• pp.429-440
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• 2006

This paper comprises two specific objectives. The first is to examine the applicability of ordinary kriging interpolation(OK) to the p-adaptivity of the finite element method that is based on variogram modeling. The second objective Is to present the adaptive procedure by the hierarchical p-refinement in conjunction with a posteriori error estimator using the modified S.P.R. (superconvergent patch recovery) method. The ordinary kriging method that is one of weighted interpolation techniques is applied to obtain the estimated exact solution from the stress data at the Gauss points. The weight factor is determined by experimental and theoretical variograms for interpolation of stress data apart from the conventional interpolation methods that use an equal weight factor. In the p-refinement, the analytical domain has to be refined automatically to obtain an acceptable level of accuracy by increasing the p-level non-uniformly or selectively. To verify the performance of the modified S.P.R. method, the new error estimator based on limit value has been proposed. The validity of the proposed approach has been tested with the help of some benchmark problems of linear elastic fracture mechanics such as a centrally cracked panel, a single edged crack, and a double edged crack.

• Journal of Korea Technology Innovation Society
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• v.14 no.1
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• pp.22-39
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• 2011

This study examines the wage level from a viewpoint of major-job match as part of an analysis on the skill mismatch problem in 4-year college graduates. The empirical analysis explicitly incorporate the sample selection bias as an econometric problem not only suggested but merely introduced in the earlier studies. This study also set up a major-job match variable, which was usually handled as a binary variable for analytical convenience, as a polychotomous choice variable in selection equation as provided by the survey. In particular, it considered multi-cohort survey on graduates of the years 1982, 1992, and 2002 for the empirical analysis. As a result of empirical analysis, the wage premium of a major-job match was identified. This result was consistent after the consideration of a sample selection bias and also after modeling the major-job match variable as polychotomously selective. Through an analysis classified by the major, this study identified a relatively high wage premium among Social Science, Engineering, and Science majors. However, there was a difference in the effect of selection among these majors. Also, by assessing cohort effects this study found that the skill mismatch had rapidly progressed in 1992, while difference between 1992 and 2002 cohorts are insignificant. The analysis suggests that wage level is better understood within the context of both sample selection and major-job match, and regardless of model specification the major-job match affects wage strongly.

• Cartoon and Animation Studies
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• s.46
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• pp.1-22
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• 2017

The practical learning requires the new paradigm in its content of education and environment along with the rapid development of information communication technology and the expansion of digital content industry. Especially, the animation education, core area of digital content industry, has attempted to improve the content and method of education by focusing on creativity, convergence and practical education. However, education environment in the previous form of computer laboratory has not been reflected the characteristics of animation education. In the light of this, this research would suggests the effective education environment implemented animation job competency and the characteristics of animation production. Firstly, the problem of previous educational environment will be explored through looking at computer rooms of domestic Universities. The characteristics of animation production consisted of Pre-production, Main-production, Post-production and elements of animation job competency will be reviewed by focusing on three phases of production, Pre-production, Main-production and Post-production, and six particular jobs, concept art, modeling & texturing, animating, lighting, VFX and compositing. Secondly, 6 types of space adapted from space syntax, possibly explored the embedded meaning of the structure of space and environment, will be reviewed by focusing on integration, separation and interaction. Thirdly, based on the characteristics of animation production, the element of animation job competency, 6 types of space, analytical tools about animation project education will be deducted, and the case study regarding animation studio, Walt Disney studio, will be processed by focusing on its production environment and spatial composition by focusing on Pre-production, Main-production, Post-production. Fifthly, the effective spatial composition for animation project education will be explored based on the interpretation of literature reviews and case study. In regard to this, the research addresses the spatial composition reflected the characteristics of practical learning and job competency in animation education, which differs from the previous form of standardized education spaces.

• The Journal of Society for e-Business Studies
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• v.16 no.4
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• pp.125-137
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• 2011

Product reviews in online shopping sites can serve as a useful guideline to buying decisions of customers. However, due to the massive amount of such reviews, it is almost impossible for users to read all the product reviews. For this reason, e-commerce sites provide users with useful reviews or statistics of ratings on products that are manually chosen or calculated. Opinion mining or sentiment analysis is a study on automating above process that involves firstly analyzing users' reviews on a product to tell if a review contains positive or negative feedback, and secondly, providing a summarized report of users' opinions. Previous researches focus on either providing polarity of a user's opinion or summarizing user's opinion on a feature of a product that result in relatively low usage of information that a user review contains. Actual user reviews contains not only mere assessment of a product, but also dissatisfaction and flaws of a product that a user experiences. There are increasing needs for effective analysis on such criteria to help users on their decision-making process. This paper proposes a model that stores various types of user reviews in a data warehouse, and analyzes integrated reviews dynamically. Also, we analyze reviews of an online application shopping site with the proposed model.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.191-202
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• 2017

The purpose of this study is to develop an engineer competency model using Analytical Hierarchy Process (AHP) to improve the national technical qualification system. Korea has managed technical human resources at the government level through the operation of a national technical qualification system that certifies engineers with national certificates or technical grades by laws. However, there have been increasing concerns that the government system is separated from global standards and does not reflect an engineer's comprehensive capabilities. For these reasons, the new architecture of the system has been continuously discussed and becomes a major policy issue of the Korean government. For the development of the engineer competency model, domestic and global models were separately structured using 554 valid questionnaires with a consistency ratio (CR) of 0.1 or less. The relative importance of engineer competency factors in a domestic model was career (0.383), qualification (0.253), academic degree (0.195), and job training (0.169) whereas the order in the global model was career (0.308), global ability (0.237), job training (0.175), domestic qualification (0.147), and academic degree (0.134). The results of AHP analysis indicated that the evaluation factors and methods recognized by engineers were different from a current government model focusing on domestic qualifications. There was also perceptual difference in the importance of engineer evaluation factors between groups depending on the type of organizations and markets. This means that it is necessary to reflect the characteristics of organizations and markets when evaluating engineer competency. Based on AHP analysis and literature reviews, this paper discussed how to develop a new engineer competency index (ECI) and presented two effective index models verified by simulation test using 59,721 engineers' information. Lastly, the paper discussed major findings of our empirical research and proposed policy alternatives for the improvement of a national engineer qualification system. The paper contributes to the management of technical human resources since it provides quantitative competency models that are objectively developed by reflecting market recognition and can be effectively used by the policy makers or firms.