• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.76-81
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• 2017

In this research, to cope with the exhaust being reviewed to establish legal regulations for domestic small vessels, a basic experiment on an exhaust emissions post-treatment system was conducted to construct the design data required for securing a localized technology. The data was secured based on the arithmetic mean calculated through setting the engine load to 25%, 50%, and 75% and conducting five. A 2800-cc turbo charger diesel-type engine was used in the experiment, and an engine dynamometer was used in the conducted tests. As a result, NOx was reduced by approximately 20% and PM was reduced by approximately 97%. Although the results indicated no significant changes to CO in test mode-1, it was greatly reduced as it transitioned into the next phase.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.28-35
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• 2000

In order to acquire the precise and fast response for an analytical query, proper selection of the views to materialize in data warehouse is very crucial. In traditional algorithms, the whole relation is considered to be selected as materialized views. However, materializing the whole relation rather than a part of relation results in much worse performance in terms of time and space cost. Therefore, we present a new algorithm for selection of views to materialize using clustering method in order to improve the performance of data warehouse including this problem. In the presented algorithm, ASVMR(Algorithm for Selection of Views to Materialize using Reduced table), we first generate reduced tables in data warehouse using automatic clustering based on attribute-values density, then we consider the combination of reduced tables as materialized views instead of the combination of the original base relations. We also show the experimental results in which both time and space cost are approximately 1.8 times better than the conventional algorithms.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.382-384
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• 2002

Filtered-Back-Projection technique is used in X-ray CT image reconstruction. This requires X-ray transmission data from all directions. As the transverse cross-section of the body is approximately 50 cm, transmitted X-rays in this direction are strongly attenuated. If X-ray transmission data in this direction is avoided, exposure to the patients seems to be reduced one 20th of usual value. Some alternative method has to be found for clinically sufficient image quality. New methods are under development and tentative results are reported that utilizes the principle of superposition.

• Journal of Biosystems Engineering
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• v.16 no.1
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• pp.9-17
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• 1991

A dynamometer was designed and constructed to measure three directional forces and moments of pull type implement with eliminating the interference between the forces. The dynamometer consists of a linear motion bearing, self-aligning bearings, universal joints, and cantilevers where strain gages were attached. A data acuquisition system was developed to collect data and to analyze them. The data acuquisition system consists of the dynamometer, a potentiometer to measure the implement depth, strain amplifiers, a A/D converter, and an IBM-AT compatible microcomputer. Program, written in C language, was developed to read data from tranducers with given interval, to calculate forces and moments, to display them on screen, and to store them on disk. The calibration results showed that cantilevers had good linearity and there was no interference among directional forces. When applied loads were reduced with constant rate, hysteresis was appeared on the dynamometer. It might to be reduced by using ball bearings instead of self-aligning bearings.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10a
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• pp.363-366
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• 2001

It is very difficult to maintain the performance of estimation models for the new breed of projects since the computing environment changes so rapidly in terms of programming languages, development tools, and methodologies. So, we propose to use the relevant cases for a neural network model, whose cost is the decreased number of cases. To balance the relevance and data availability, the qualitative input factors are used as criteria of data classification. With the data sets that have the same value for certain qualitative input factors, we can eliminate the factors from the model making reduced neural network models. So we need to seek the optimally reduced neural network model among them. To find the optimally case-selective neural network, we propose the search techniques and sensitivity analysis between data points and search space.

• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
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• 2003.09a
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• pp.1-1
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• 2003

In this talk, a reduced-order modeling methodology based on centroidal Voronoi tessellations (CVT's)is introduced. CVT's are special Voronoi tessellations for which the generators of the Voronoi diagram are also the centers of mass (means) of the corresponding Voronoi cells. The discrete data sets, CVT's are closely related to the h-means clustering techniques. Even with the use of good mesh generators, discretization schemes, and solution algorithms, the computational simulation of complex, turbulent, or chaotic systems still remains a formidable endeavor. For example, typical finite element codes may require many thousands of degrees of freedom for the accurate simulation of fluid flows. The situation is even worse for optimization problems for which multiple solutions of the complex state system are usually required or in feedback control problems for which real-time solutions of the complex state system are needed. There hava been many studies devoted to the development, testing, and use of reduced-order models for complex systems such as unsteady fluid flows. The types of reduced-ordered models that we study are those attempt to determine accurate approximate solutions of a complex system using very few degrees of freedom. To do so, such models have to use basis functions that are in some way intimately connected to the problem being approximated. Once a very low-dimensional reduced basis has been determined, one can employ it to solve the complex system by applying, e.g., a Galerkin method. In general, reduced bases are globally supported so that the discrete systems are dense; however, if the reduced basis is of very low dimension, one does not care about the lack of sparsity in the discrete system. A discussion of reduced-ordering modeling for complex systems such as fluid flows is given to provide a context for the application of reduced-order bases. Then, detailed descriptions of CVT-based reduced-order bases and how they can be constructed of complex systems are given. Subsequently, some concrete incompressible flow examples are used to illustrate the construction and use of CVT-based reduced-order bases. The CVT-based reduced-order modeling methodology is shown to be effective for these examples and is also shown to be inexpensive to apply compared to other reduced-order methods.

• Journal of Mechanical Science and Technology
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• v.18 no.5
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• pp.865-876
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• 2004

A new concept of reduced quasi-dimensional combustion model for a direct injection diesel engine is developed based on the previously developed quasi-dimensional multi-zone model to improve the computational efficiency. In the reduced model, spray penetration and air entrainment are calculated for a number of zones within the spray while three zones with aggregated spray zone concept are used for the calculation of spray combustion and emission formation processes. It is also assumed that liquid phase fuel appears only near the nozzle exit during the breakup period and that spray vaporization is immediate in order to reduce the computational time. Validation of the reduced model with experimental data demonstrated that the new model can predict engine performance and NO and soot emissions reasonably well compared to the original model. With the new concept of reduced model, computational efficiency is significantly improved as much as 200 times compared to the original model.

• Elastomers and Composites
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• v.51 no.4
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• pp.308-316
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• 2016

The rubber materials are widely used in automobile industry due to their capability of a large amount of elastic deformation under a force. Current trend of design process requires prediction of functional properties of parts at early stage. The behavior of rubber material can be modeled using strain energy density function. In this study, five different strain energy density functions - Neo-Hookean model, Reduced Polynomial $2^{nd}$ model, Ogden $3^{rd}$ model, Arruda Boyce model and Van der Waals model - were used to estimate the behavior of carbon black added natural rubber under uniaxial load. Two kinds of tests - uniaxial tension test and biaxial tension test - were performed and used to correlate the coefficients of the strain energy density function. Numerical simulations were carried out using finite element analysis and compared with experimental results. Simulation revealed that Ogden $3^{rd}$ model predicted the behavior of carbon added natural rubber under uniaxial load regardless of experimental data selection for coefficient correlation. However, Reduced Polynomial $2^{nd}$, Ogden $3^{rd}$, and Van der Waals with uniaxial tension test and biaxial tension test data selected for coefficient correlation showed close estimation of behavior of biaxial tension test. Reduced Polynomial $2^{nd}$ model predicted the behavior of biaxial tension test most closely.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.435-440
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• 2006

The Reduced Vertical Separation Minimum (RVSM), which is the reduced minimum from 2,000 ft to 1,000 ft at flight levels (FL) between 290 and FL410 inclusive, was implemented in 30 September 2005 within the Japanese domestic airspace. Prior to the implementation, safety assessment for the airspace in assumed RVSM environments was carried out. Some model parameter values of collision risk model were estimated using flight plan (progress) data and radar data. An estimate of vertical collision risk including operational risk was calculated using these together with given parameter values. The results obtained from this analysis are as follows. (1) Contribution of the vertical collision risk for the crossing routes is about 9 percents of the total technical risk. (2) The estimate of the collision risk is $4.1{\times}10^{-9}$ [fatal accidents / flight hour] and the value is smaller than a maximum allowable level of collision risk, i.e. $5{\times}10^{-9}$ [fatal accidents / flight hour], called the Target Level of Safety.

• The Korean Journal of Emergency Medical Services
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• v.19 no.3
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• pp.19-32
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• 2015

Purpose: This study examined the effect of wearing personal protective equipment (PPE) on cardiopulmonary resuscitation (CPR), positive airway pressure, and the posture of emergency medical technicians (EMTs) when conducting CPR. Methods: Twenty 119 EMTs performed 30:2 CPR on a manikin for 4 min. Imaging data were digitized with Kwon3D XP (version 4.0). Data were collected by analyzing the motion when starting in one cycle, such as pressing to the maximum and in the final position (relaxed), and were analyzed with SPSS 18.0. Results: The angle of the elbow joints was significantly reduced (p < .05). The trunk angle was statistically significantly (p < .01, p < .001) increased. The angular velocities of the shoulder joint and left elbow joint were reduced (p > .05). The angular velocity of the trunk was significantly reduced in the starting and maximum compression postures. The hand-escape time was increased. The average compression depth was increased but not significantly (p > .05). The positive airway pressure was reduced (p > .05). Conclusion: The angle of the elbow joints and the angular velocity of the trunk were reduced, and the angle of the trunk was increased. The success of CPR and positive airway pressure was reduced.