• Research in Mathematical Education
• /
• v.6 no.1
• /
• pp.81-96
• /
• 2002

This article describes a research project that examined the impact of hand-held technology on students' understanding linear equations and graphs in multiple representations. The results indicated that students in the graphing-approach classes were significantly better at the components of interpreting. No significant differences between the graphing-approach and traditional classes were found fur translation, modeling, and algebraic skills. Further, students in the graphing-approach classes showed significant improvements in their attitudes toward mathematics and technology, were less anxious about mathematics, and rated their class as more interesting and valuable.

• East Asian mathematical journal
• /
• v.36 no.1
• /
• pp.55-60
• /
• 2020

We study a probabilistic approach for valuing an exchange option with default risk. The structural model of Klein [6] is used for modeling default risk. Under the structural model, we derive the closed-form pricing formula of the exchange option with default risk. Specifically, we provide the pricing formula of the option with the bivariate normal cumulative function via a change of measure technique and a multidimensional Girsanov's theorem.

• Journal of Electrical Engineering and information Science
• /
• v.2 no.4
• /
• pp.92-98
• /
• 1997

This paper presents a new approach to obtaining a reduced-order model for multi-module converters. The proposed approach can be used to derive the reduced-order model for a wide class of multi-module converters including pulse-width-modulated (PWM) converters, soft-switched PWM converters, and resonant converters. The reduced-order model has the structure of a conventional single-module converter while preserving the dynamics of the original multi-module converter. Derivation procedures and the use of the reduced-order model is demonstrated using a three-module boost converter.

• Proceedings of the Korea Society for Simulation Conference
• /
• 2003.11a
• /
• pp.19-25
• /
• 2003

Since container throughput is continually increasing, the main issues facing decision-makers at port container terminals are how to expand the existing container terminals and construct new container terminals. Simulations that support user needs require modeling tools that are both easy to use and sufficiently to reflect real world system. The object-oriented approach provides for both reusability and modularity that best fits these requirements. This paper present the design procedure a simulator for port container terminal that was based on the object-oriented approach. The simulator in order to model and simulate the TC-based container terminals is developed.

• Structural Engineering and Mechanics
• /
• v.50 no.6
• /
• pp.755-772
• /
• 2014

A simplistic approach towards evaluation of complete load deflection response of Reinforced Concrete (RC) flexural members under post fire (residual) scenario is presented in this paper. The cross-section of the RC flexural member is divided into a number of sectors. Thermal analysis is performed to determine the temperature distribution across the section, for given fire duration. Temperature-dependent stress-strain curves for concrete and steel are then utilized to perform a moment-curvature analysis. The moment-curvature relationships are obtained for beams exposed to different fire durations. These are then utilized to obtain the load-deflection plots following pushover analysis. Moreover one of the important issues of modeling the initial stiffness giving due consideration to stiffness degradation due to material degradation and thermal cracking has also been addressed in a rational manner. The approach is straightforward and can be easily programmed in spreadsheets. The presented approach has been validated against the experiments, available in literature, on RC beam subjected to different fire durations viz. 1hr, 1.5hrs and 2hrs. Complete load-deflection curves have been obtained and compared with experimentally reported counterparts. The results also show a good match with the results obtained using more complicated approaches such as those involving Finite element (FE) modeling and conducting a transient thermal stress analysis. Further evaluation of the beams during fire (at elevated temperatures) was performed and a comparison of the mechanical behavior of RC beams under post fire and during fire scenarios is made. Detailed formulations, assumptions and step by step approach are reported in the paper. Due to the simplicity and ease of implementation, this approach can be used for evaluation of global performance of fire affected structures.

• Geomechanics and Engineering
• /
• v.33 no.1
• /
• pp.11-18
• /
• 2023

This study explores a new energy partitioning approach to determine the fracture toughness of 3-D printed pristine/recycled high density polyethylene (HDPE) blends employing the essential work of fracture (EWF) concept. The traditional EWF approach conducts a uniaxial tensile test with double-edge notched tensile (DENT) specimens and measures the total energy defined by the area under a load-displacement curve until failure. The approach assumes that the entire total energy contributes to the fracture process only. This assumption is generally true for extruded polymers that fracture occurs in a material body. In contrast to the traditional extrusion manufacturing process, the current 3-D printing technique employs fused deposition modeling (FDM) that produces layer-by-layer structured specimens. This type of specimen tends to include separation energy even after the complete failure of specimens when the fracture test is conducted. The separation is not relevant to the fracture process, and the raw experimental data are likely to possess random variation or noise during fracture testing. Therefore, the current EWF approach may not be suitable for the fracture characterization of 3-D printed specimens. This paper proposed a new energy partitioning approach to exclude the irrelevant energy of the specimens caused by their intrinsic structural issues. The approach determined the energy partitioning location based on experimental data and observations. Results prove that the new approach provided more consistent results with a higher coefficient of correlation.

• Korean Journal of Computational Design and Engineering
• /
• v.1 no.1
• /
• pp.45-55
• /
• 1996

This paper presents a new approach to non-parametric modeling of cutter swept surface (CSS) for cutting simulation. Instead of explicitly modeling cutter swept volumes, silhouette curves of the cutter surface are utilized in computing the z-value of the CSS at a grid point on the x,y-plane. The non-parametric evaluation of the CSS constitutes the integral part of 3-axis cutting simulation. The proposed method is more efficient than the existing ones in the case of conventional cutters (i.e., ball-end mills and flat-end mills), and more importantly, it enables the non-parametric modeling of the CSS for the round-end mills which was not possible with the existing methods.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.11
• /
• pp.1988-1993
• /
• 2008

Photovoltaic (PV) modules operate over a large range of conditions but manufacturer's information is not sufficient to determine their overall performance. Designers need a reliable tool to predict energy production from a photovoltaic module under all conditions in order to make a sound decision. The modeling method of photovoltaic (PV) module are useful to perform detailed analysis of PV system performance for changing meteorological conditions, verify actual rated power of PV system sizing and determine the optimal design of PV system and components. This paper indicates a modeling approach of PV module performance in terms of meteorological conditions and identifies validity of PV modules modeling by comparing measured with simulated value.

• IE interfaces
• /
• v.16 no.2
• /
• pp.258-267
• /
• 2003

Recently, virtual reality technologies have been rapidly developed and realtime virtual simulation methods have been extensively employed for several application areas such as game, sports, manufacturing, military, and so on. A 3D database in realtime virtual simulation plays a key role because it makes users feel reality in virtual space. In a application view of 3D database, a systematic construction approach is required to reduce its construction time and increase its quality. However, many researches have been mostly focused on realtime graphic issues and its key technologies. In virtual simulation of transportation equipments, this paper proposes a systematic construction process of 3D database consisting of four stages as follows: 1) determine the activity space of a equipment, 2) collect data related to 3D database construction, 3) make a 3-dimensional modeling strategy, and 4) generate and evaluate a 3D model. This paper also introduces a new procedure of 3D environment modeling, which summarizes and expands our modeling experiences, to be used as a modeling guide.

• Structural Engineering and Mechanics
• /
• v.18 no.1
• /
• pp.113-124
• /
• 2004

The information on local stress acting in a bridge is required in many occasions such as fatigue assessment. The analysis by beam elements cannot yield this class of information adequately, while the finite element modeling of an entire long-span bridge by shell elements is impractical. In the present study, the hybrid modeling is tried out: only part of a bridge in which the point of interest is located is discretized by shell elements and the remaining part is modeled by beam elements. By solving a simple box girder problem, the effectiveness of this approach is discussed. This technique is then applied to the Rama IX Bridge for local stress evaluation. The numerical results compare very well with the results of a full-scale static loading test. The present research thus offers a practical yet accurate technique for the stress analysis of a long-span cable-stayed bridge.