• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5689-5695
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• 2012

In this study, vibration properties of seat and human body are analyzed through test and numerical analysis methods by taking into account the viscoelastic characteristics of polyurethane foam as seat material which is applied for vehicle. These viscoelastic characteristics which show nonlinear and quasi-static behavior are obtained by compression test. In addition, the viscous elastic property of polyurethane foam is modelled mathematically by using convolution integral and nonlinear stiffness model. In order to analyze the performance on ride comfort of seat, vertical vibration model is established by using dynamic model of seat and vertical vibration model of human body at ISO5982, and so the related motion equations are derived. A numerical analysis simulation is applied by using the nonlinear motion equation with Runge-Kutta integral method. The dynamic responses of seat and human body on the input of vibration acceleration measured at the floor of the railway vehicle are examined. The variation of the index value at ride comfort on seat design parameters is analyzed and the methodology on seat design is suggested.

• Journal of KIISE:Databases
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• v.34 no.4
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• pp.315-327
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• 2007

The performance of database applications with large sets of multidimensional data depends on the performance of its access methods and the underlying disk system. In modeling the disk system, even though modem disks are manufactured with multiple physical zones, conventional access methods have been developed based on a traditional disk model with many simplifying assumptions. Thus, there is a marked lack of investigation on how to enhance the performance of access methods given a zoned disk model. The paper proposes novel zoning techniques that can be applied to any multidimensional access methods, both static and dynamic, enhancing the effective data transfer rate of underlying disk system by fully utilizing its zone characteristics. Our zoning techniques include data placement algorithms for multidimensional index structures and accompanying localized query processing algorithms for range queries. The experimental results show that our zoning techniques significantly improve the query performance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.61-65
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• 2006

A thery was developed to design a high pressure vessel with combined structure of the metal and the composite to withstand the pressure of several tens of thousands psias to reduce the weight of the impulse motor which produces high level of thrust within several tens of seconds. The elastic-plastic stress analyses were carried out to prove the validity of the design theory A combustion chamber of the impulse motor was designed by the design theory, fabricated, and tested by the hydraulic pressure and the static firings. The bursting pressures from the tests were compared to those predicted by tile design theory and the stress analyses and found to be almost the same. It will be possible to design the high pressure vessel with combined structure of the metal and the composite very easily by the proposed design theory.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.118-122
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• 2006

For the development of a gas generator of a liquid rocket engine, the prediction of thermodynamic properties of combustion gas with respect to a propellant mixture ratio becomes critical. The present study focuses on the temperature measurement of exit combustion gas as a function of a mixture ratio through combustion tests of a fuel-rich gas generator propelled by Lox/Jet A-1. The measurement of combustion dynamic and static pressures allowed indirect estimation of thermodynamic properties like specific heat ratio, gas constant, and constant pressure specific heat. Comparing the results with empirical prediction through an interpolation reveals that the interpolation method calibrated using temperature results can be utilized as an effective tool for the design of a fuel-rich gas generator.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.265-269
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• 2006

Anti-Roll Tanks, also called Sloshing Tanks, is a rather common and sometimes an efficient method of limiting the roll angles. The important parameters, when considering using anti-roll tanks, are positioning, size, duct area, flow control device etc. Measurement by the PIV(Particle Image Velocimetry) was conducted to investigate the flow characteristics around control damper and inlet area of duct for three kind of inclined angle $(\alpha=0^*,\;10^*\;and\;20^*)$. Flow behaviors such as instantaneous and time-mean velocity vectors are investigated. Furthermore, to reveal boundaries between flowing and stagnant zones and to extract velocity profiles at any selected sections of the lower duct for passive anti-rolling tanks system.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.1
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• pp.81-90
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• 2016

The Agricultural Systems Application Platform (ASAP) provides bottom-up modelling and simulation environment for agricultural engineer. The purpose of this study is to expand usability of the ASAP to the second order partial differential equations: elliptic equations, parabolic equations, and hyperbolic equations. The ASAP is a general-purpose simulation tool which express natural phenomenon with capsulized independent components to simplify implementation and maintenance. To use the ASAP in continuous problems, it is necessary to solve partial differential equations. This study shows usage of the ASAP in elliptic problem, parabolic problem, and hyperbolic problem, and solves of static heat problem, heat transfer problem, and wave problem as examples. The example problems are solved with the ASAP and Finite Difference method (FDM) for verification. The ASAP shows identical results to FDM. These applications are useful to simulate the engineering problem including equilibrium, diffusion and wave problem.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6082-6089
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• 2013

The supply of DSLR cameras has increased recently. Because of its widespread use, different types of DSLR camera video techniques have also been developed. Time-lapse is an effective filming technique that helps produce a fine-quality video clip by taking pictures of multiple camera shots during certain time intervals without recording the actual video clip, as the existing technique does. Machinery equipment (dolly), which controls the speed of movement and shutter, needs to be deleted. This paper introduces a method for a designing movement system that satisfies the design conditions. In addition, this paper proved the validity of the design by performing stress analysis on the static and dynamic conditions of the final design.

• Journal of Korea Multimedia Society
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• v.10 no.8
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• pp.967-980
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• 2007

Video objects of interest play an important role in representing the video content and are useful for improving the performance of video retrieval and compression. The objects of interest may be a main object in describing contents of a video shot or a core object that a video producer wants to represent in the video shot. We know that any object attracting one's eye much in the video shot may not be an object of interest and a non-moving object may be an object of interest as well as a moving one. However it is not easy to define an object of interest clearly, because procedural description of human interest is difficult. In this paper, a set of four filtering conditions for extracting moving objects of interest is suggested, which is defined by considering variation of location, size, and moving pattern of moving objects in a video shot. Non-moving objects of interest are also defined as another set of four extracting conditions that are related to saliency of color/texture, location, size, and occurrence frequency of static objects in a video shot. On a test with 50 video shots, the segmentation method based on the two sets of conditions could extract the moving and non-moving objects of interest chosen manually on accuracy of 84%.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.2
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• pp.183-194
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• 2002

The clustering environment with heterogeneous workstations provides the cost effectiveness and usability for executing applications in parallel. Load balancing is considered a necessary feature for a cluster of heterogeneous workstations to minimize the turnaround time. Previously, static load balancing that assigns a predetermined weight for the processing capability of each workstation, or dynamic approaches which execute a benchmark program to get relative processing capability of each workstation were proposed. The execution of the benchmark program, which has nothing to do with the application being executed, consumes the computation time and the overall turnaround time is delayed. In this paper, we present efficient methods for task distribution and task migration, based on the relative load index. We designed and implemented a load balancing system for the clustering environment with heterogeneous workstations. Turnaround times of our methods and the round-robin approach, as well as the load balancing method using a benchmark program, were compared. The experimental results show that our methods outperform all the other methods that we compared.

• Journal of Korea Multimedia Society
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• v.3 no.5
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• pp.516-525
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• 2000

A lot of efforts have been made to develop a new technology for efficient distance education based on a powerful Internet service like World Wide Web. By developed distance education systems, we can study something we want at anytime and anywhere. However in spite of the excellent achievements we have made, something insufficient still is remained. Distance education methods only depending on static homepages or voices and simple drawings may be insufficient to support as much effects as in real class. So it is necessary to develop a new method for teaching students more feasibly and efficiently In this paper, we try to design and implement a lecture authoring system that offers effective distance education with voices, animations, camera images, drawings and etc.. We can expect the designed system can give more efficient education effects like a face-to-face lecture in real class. The enclosed function of intense compression enables to transmit the lectures more speedily. Besides it has caption processing function to serve additional informations to students with caption texts, messages and hyperlinks.