• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.5
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• pp.237-244
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• 2017

This study proposes a numerical model to explain the closely placed double modes in the vibration of a layered stone pagoda system. The friction surface between the stones is modelled as the Timoshenko finite element while each stone layer is modelled as a rigid body. It is assumed that the irregular asperity on the friction surface enables the stone to be excited. This results in the closely placed modes that are composed of natural modes and self-excited modes. To examine the validity of the proposed model, a set of modal testing and analysis for a layered stone pagoda mock-up model has been conducted and a set of closely placed double modes are extracted. Applying the extended sensitivity-based system identification technique, the various system parameters are identified so that the modal parameters of the proposed numerical model are the same with those of the experimental mock-up. For a horizontal impulse excitation, the simulated acceleration responses are compared with measurements.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.12 no.1
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• pp.45-53
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• 2006

Thermal insulation is used in a variety of applications to protect temperature sensitive products from thermal damage. Several factors affect the performance of insulation packages. Among these factors, the thermal resistance of the insulating wall is the most important factor to determine the performance of the insulating package. In many cases, insulating wall consists of multi-layered structure and the heat transfer through this structure is a very complex process. In this study, an one-dimensional mathematical model, which includes all of the heat transfer principles covering conduction, convection and radiation in multi-layered structure, were developed. Based on this model, several heat transfer phenomena occurred in the air space between the layer of the insulating wall were investigated. From the simulation results, it was observed that the heat transfer through the air space between the layer were dominated by conduction and radiation and the low emissivity of the surface of each solid layer of the wall can dramatically increase the thermal resistance of the wall. For practical use, an equation was derived for the calculation of the thermal resistance of a multi-layered wall.

• Journal of the Korean Data and Information Science Society
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• v.14 no.4
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• pp.825-836
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• 2003

Based on customer information and financing processes in capital market, we derived individual models by applying multi-layered perceptrons, MDA, and decision tree. Further, the results from the existing single models were compared with the results from the integrated model that was developed using genetic algorithm. This study contributes not only to verifying the existing individual models and but also to overcoming the limitations of the existing approaches. We have depended upon the approaches that compare individual models and search for the best-fit model. However, this study presents a methodology to build an integrated data mining model using genetic algorithm.

• Journal of the Korean GEO-environmental Society
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• v.10 no.7
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• pp.159-165
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• 2009

The Strain Wedge Model is useful method for horizontal bearing capacity calculation considering interaction of pile and ground deformation. However, application case of the Strain Wedge Model is rare and the strain wedge model of plenty of verification is needed on multi layered ground in Korea. In this present study, to conduct laboratory model test and numerical analysis for verification of Strain Wedge Model, adapt model that could describe the interaction of pile and ground deformation on multi layered ground. In model test, it was performed to estimate the behavior characteristics on pile under lateral load and to analyze the relationship between load and deformation. In addition, it was fulfilled to measure the skin friction on pile using strain gauge and to decide the ground passive resistance wedge using skin friction. Numerical analysis was performed to verify laboratory model test results.

• Korea-Australia Rheology Journal
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• v.18 no.4
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• pp.217-224
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• 2006

Rapid flow advancement without void formation is essential in the liquid composite molding (LCM) such as resin transfer molding (RTM) and vacuum assisted resin transfer molding (VARTM). A highly permeable layer in multi-layered preform has an important role in improvement of the flow advancement. In this study, a multi-layered preform which consists of three layers is employed. Radial flow experiment is carried out for the multi-layered preform. A new analytic model for advancement of flow front is proposed and effective permeability is defined. The effective permeability for the multi-layered preform is obtained analytically and compared with experimental results. Compaction test is performed to determine the exact fiber volume traction of each layer in the multi-layered preform. Transverse permeability employed in modeling is measured experimentally unlike the previous studies. Accurate prediction of flow advancement is of great use for saving the processing time and enhancing product properties of the final part.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.65-70
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• 2005

This paper introduces an approach to multi-layered product knowledge model for collaborative engineering environment. The participants in collaborative engineering want to share and reason product knowledge through internet without any heterogeneity and ambiguity. However the previous knowledge models are limited in providing those aspects. In this paper, the collaborative engineering domain is analyzed and then the product knowledge is organized into four levels such as product context model, product specific model, product design model and product manufacturing model. The four levels are represented by first-order logic in layered fashion. The concepts and the instances of a formal ontology are used for recursive representation of the four levels. The instances of the concepts of an upper level like product context model are considered as the concepts of an adjacent lower level like product specific model, and this mechanism is applied to the other levels. These logic representations are integrated with the schema and the instances of a relational database. OWL representation of the four levels is defined through the integration of the logic representation and OWL primitives. The four product knowledge models have their major representation according to the characteristics of each model. This approach enables engineer to share product knowledge through internet without any ambiguity and utilize it as basis for additional reasoning.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1759-1772
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• 1994

In this study, we re-examined the Tate's modified Bernoulli equation to study penetration phenomena for long rod projectile into single or multi-layered finite thickness plates. We used the force equlibrium equation at mushroomed nose/target interface instead of conventional pressure equation at the stagnation point. In our penetration model, we considered the velocity dependent $R_t$ value for semi-infinite target and considered only the back face effect for finite target. To compensate for $R_t$ value according to target's thickness and back face effect, we used the spherical cavity expansion theory for semi-infinite plate and used the cylindrical cavity expansion theory for finite plate. Also we developed the experimental technique using make screen to measure the penetration duration time at each layered plate. In 3-layered laminated RHA/mild steel/ A1 7039 plate, we observed that spall had occured around the back face of A1 7039 plate by the stress wave interaction. Through the comparison between theoretical and experimental data including Lambert's results, we conform that our study has good confidences.

• ETRI Journal
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• v.30 no.1
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• pp.13-20
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• 2008

We evaluate the sink capacity of wireless code division multiple access (CDMA) sensor networks with layered architecture. We introduce a model of interference at a sink considering two kinds of interference: multiple access interference (MAI) and node interference (NI). We also investigate the activity of sensor nodes around the sink in relation to gathering data under a layered architecture. Based on the interference model and the activity of sensor nodes around the sink, we derive the failure probability of the transmission from a source node located one hop away from the sink using Gaussian approximation. Under the requirement of 1% failure probability of transmission, we determine the sink capacity, which is defined as the maximum number of concurrent sensor nodes located one hop away from the sink. We demonstrate that as the node activity of the MAI decreases, the variation of the sink capacity due to the node activity of the NI becomes more significant. The analysis results are verified through computer simulations.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.4
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• pp.97-103
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• 2012

This study investigates thermal insulation properties of multi layer materials depending on thickness of air layers. Numerical analysis on the heat flow of different insulating materials was conducted to identify whether their temperature distributions demonstrate the reduced rate of heat transfer conclusively or not. Analytical model is divided into two categories. One is to distinguish temperature distribution of the air-layer materials from the non-air layer ones. The other is to compare the efficacy between eight-layered insulating materials with no air-layer contained and three-layered insulating materials which include an air-layer definitely. In the latter case, the identical thickness is assigned to each material. The effect of thermal insulation by including an air-layer is verified in the first analytical model. The result of the second model shows that the insulation of the eight-layered materials is coterminous at the three-layered ones with an air-layer and the thermal insulation of the two materials is imperceptible. The benefits of cost and energy saving are anticipated if air-layers are efficiently incorporated in multi layer insulating materials in a greenhouse.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.3
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• pp.139-144
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• 2013

In Korea, where most of the sites are narrow in space and their earth resistivity is relatively high, the spaces between grounding conductors are likely to be designed narrow in order to lower ground resistance and dangerous voltage below to the permitted safety values. In addition, ground nets are in the shape of square or rectangle depending on the location and size of the facilities and ground contact area, and inner conductors are laid out in grids like the pattern of nets. Nevertheless, with the existing designs, the marginal voltage for safety gets higher as the area is extended further outside, in comparison with that of inner mesh grounding, thus causing much difficulty maintaining them equipotential, and there exist limits in the burial, grounding grid design considering the dangerous voltage of muti-layered model in the constrained sites, was studied.