• International conference on construction engineering and project management
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• 2007.03a
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• pp.239-248
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• 2007

In the highly competitive construction industry, a slight inaccuracy of estimation can easily cause the loss of a project. Erroneous experience-based cost estimates or allocations of on-site supervisory manpower often offset the profit gained from the project and may jeopardize the management processes. To counter these types of problems, we develop a model using mathematical analysis and case-based reasoning to automate the allocation of on-site supervisory manpower and estimate construction site costs. The method is founded upon laborious data collection processes and analysis by matching statistical assumptions, and is applicable to construction projects. In the modeling the costs and allocation of on-site supervisory manpower are quantified for both owners and contractors before initiating or bidding on the projects. The findings confirm that the degree of variation of the model predictions has an accuracy rate at 88.47%. Single-site construction projects can be accurately predicted and the assignment of supervisory manpower feasibly automated.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.1
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• pp.10-21
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• 2008

User travel behavior is based on the existence of complete traffic information in deterministic user optimal principle by Wardrop(1952). According to deterministic user optimal principle, users choose the optimal route from origin to destination and they change their routes arbitrarily in order to minimize travel cost. In this principle, users only consider travel time as a factor to take their routes. However, user behavior is not determined by only travel time in actuality. Namely, the models that reflect only travel time as a route choice factor could give irrational travel behavior results. Therefore, the model is necessary that considers various factors including travel time, transportation networks structure and traffic information. In this research, more realistic deterministic optimal traffic assignment model is proposed in the way of route recognizance behavior. This model assumes that when users decide their routes, they consider many factors such as travel time, road condition and traffic information. In addition, route recognizance attributes is reflected in this suggested model by forward searching method and backward searching method with numerical formulas and algorithms.

• The Mathematical Education
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• v.63 no.1
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• pp.19-33
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• 2024

This study investigates longitudinal patterns in middle school students' mathematics interest and achievement using panel data from the 4th to 6th year of the Gyeonggi Education Panel Study. Results from the multivariate growth mixture model confirmed the existence of heterogeneous characteristics in the longitudinal trajectory of students' mathematics interest and achievement. Students were classified into four latent classes: a low-level class with weak interest and achievement, a high-level class with strong interest and achievement, a middlelevel-increasing class where interest and achievement rise with grade, and a middle-level-decreasing class where interest and achievement decline with grade. Each class exhibited distinct patterns in the change of interest and achievement. Moreover, an examination of the correlation between intercepts and slopes in the multivariate growth mixture model reveals a positive association between interest and achievement with respect to their initial values and growth rates. We further explore predictive variables influencing latent class assignment. The results indicated that students' educational ambition and time spent on private education positively affect mathematics interest and achievement, and the influence of prior learning varies based on its intensity. The perceived instruction method significantly impacts latent class assignment: teacher-centered instruction increases the likelihood of belonging to higher-level classes, while learner-centered instruction increases the likelihood of belonging to lower-level classes. This study has significant implications as it presents a new method for analyzing the longitudinal patterns of students' characteristics in mathematics education through the application of the multivariate growth mixture model.

• Journal of Power Electronics
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• v.17 no.2
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• pp.442-452
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• 2017

This paper deals with the input-output modeling of a vector controlled PMSM drive system and design of a simple multiple model adaptive control (MMAC) scheme with desired transient responses. We present a discrete-time modeling technique using closed-loop identification that can experimentally identify the equivalent models in the d-q coordinates. A bank of linear models for the equivalent plant of the current loop is first obtained by identifying them at several operating points of the current to account for nonlinearity. Based on these models, we suggest a simple q-axis MMAC combined with a fixed d-axis controller. After the current controller is designed, another equivalent model including the current controller in the speed control loop shall be similarly obtained, and then a fixed speed controller is synthesized. The proposed approach is demonstrated by experiments. The experimental set up consists of a surface mounted PMSM (5 KW, 220V, 8 poles) equipped with a flywheel load of 220kg and a digital controller using DSP (TMS320F28335).

• Journal of the Korean Society of Safety
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• v.28 no.5
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• pp.54-60
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• 2013

In this study, a finite element model based on the SU/PG scheme was developed to solve shallow-water equations and the influences of parameters and internal boundary conditions on depth-averaged flow behavior were investigated. To analyze the effect of roughness coefficient and eddy viscosity on flow characteristics, the developed model was applied to rectangular meandering channel with two bends, and transverse velocities and water depth distributions were examined. As the roughness coefficient adjacent to wall increased, the velocities near the wall decreased, and the reduced velocities were compensated by the expanding mid-channel velocities. In addition, the flow characteristics around a circular cylinder were analyzed by varying the internal boundary conditions as free slip and no slip. The assignment of slip condition changed the velocity distribution on the cylinder surface and reduced the magnitude of the shear stress up to one third.

• Korean Journal of Computational Design and Engineering
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• v.19 no.2
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• pp.191-201
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• 2014

A 3D CAD system that can be used on a smart device is proposed. Smart devices are now a part of everyday life and also are widely being used in various industry domains. The proposed 3D CAD system would allow modeling in a rapid and intuitive manner on a smart device when an engineer makes a 3D model of a product while moving in an engineering site. There are several obstacles to develop a 3D CAD system on a smart device such as low computing power and the small screen of smart devices, imprecise touch inputs, and transfer problems of created 3D models between PCs and smart devices. The author discusses the system design of a 3D CAD system on a smart device. The selection of the modeling operations, the assignment of touch gestures to these operations, and the construction of a geometric kernel for creating both meshes and a procedural CAD model are introduced. The proposed CAD system has been implemented for validation by user tests and to demonstrate case studies using test examples. Using the proposed system, it is possible to produce a 3D editable model swiftly and simply in a smart device environment to reduce design time of engineers.

• Journal of Software Engineering Society
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• v.28 no.1
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• pp.23-28
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• 2019

Recently, in order to effectively test deep neural network model for image processing application, researches have actively conducted to automatically generate data in corner-case that is not correctly predicted by the model. This paper proposes test data generation method that selects arbitrary words from input of system and transforms them into synonyms in order to test the bug reporter automatic assignment system based on sentence classification deep neural network model. In addition, we compare and evaluate the case of using proposed test data generation and the case of using existing difference-inducing test data generations based on various neuron coverages.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.148-154
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• 2020

This study examines room assignments to improve accessibility in a university dormitory depending on the student grade, taking into account frequency of using a certain common space. An integer programming model is presented to minimize the total moving distance from the common space to the students' rooms for accessibility. The model also constrains the maximum capacity of a room, and disallows different grade students to be assigned to the same room. This model is similar to a facility location problem used widely in the supply chain management field. Applying our optimization model to a small group at the dormitory of Unversity A as the case study, our results indicate that lower grade students are assigned rooms closer to the common space due to their higher frequency of using that space to guarantee high accessibility. Moreover, if higher grade students are prioritized to select their rooms, we suggest an objective function that imposes a penalty in cases when lower grade students select rooms with priority. Based on the results obtained, we propose assigning rooms to students in a dormitory by considering their complex requirements and convenience to use the common space.

• Journal of Biosystems Engineering
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• v.10 no.1
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• pp.69-75
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• 1985

For the purpose of estimating the operating cost for feed production, energy consumption, labor requirement, maintenance cost, and supplies and miscellaneous costs are analyzed and developed as mathematical models. Mathematical model for energy usage Consists of electrical energy, boiler fuel energy and vehicle fuel energy. The mathematil model for electrical energy usage for the swine and poultry feed mill and the complete pelleted feed mill are developed, based on the general model mill and the computer program for its design developed in Kansas State University (Park, 1982). Also, the boiler fuel energy consumption model and the vehicle fuel energy consumption model are developed by analyzing the boiler system and the vehicle operation in the warehouse. In order to develop a mathematical model for labor requirement, the data that Vosloh (1968, 1976) constructed for labor requirement in his model mill are used by assuming that his model mill is similar to this model, in terms of labor assignment standards. Maintenance and repair costs are obtained by assuming to be 5.5% of the total capital investment cost. Also, supplies and miscellaneous costs are estimated by using Vosloh's report and it is approximately 0.87 dollars per ton based on daily production.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.6
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• pp.317-326
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• 2020

Previous studies have suggested that individuals need to invest in the accumulation of career competencies. To demonstrate how to acquire career competencies, a model consisting of the knowing why, knowing how, and knowing whom competencies was actively discussed in the previous studies. This study seeks to identify the relationships among these competencies based on three ways of knowing, and their effects on perceived work performance. Furthermore, this study tried to identify the importance of each of these competencies in predicting perceived individual performance in the business workplace environment. The findings showed that the knowing why, knowing how, and knowing whom competencies all have a statistically significant positive influence on perceived individual work performance. Also, the study results showed the relative importance of the three competencies for perceived work performance. Specifically, the study results showed that the effects of the knowing why and knowing whom competencies are greater than the effect of the knowing how competency. The theoretical and practical implications of the study results were provided, including empirical evidence of the validity of the career capital model, the appropriateness of the career competency model based on the three ways of knowing, and assignment of resources for the acquisition of career competencies.