• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.668-671
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• 1997

In order to investigate the vibration characteristics of fluid-structure interaction problem, we modeled two identical rectangular plates coupled with bounded fluid. The fixed boundary condition along the plate edges and an ideal fluid were assumed. A commercial computer code, ANSYS was used to perform finite element analysis and FEM solutions were compared with the experimental results to modify the finite element model. As a result, comparison of FEM and experiment showed good agreement, and the transverse vibration modes, in-phase and out of-phase. were observed alternately in the tluid-coupled system. The effects of distance between two rectangular plates and width to length ratio on the fluid-coupled natural frequency were investigated. And it was found that the ormalized natural frequency of the fluid-coupled system monotonically increased with an increase in the number of modes.

• Laser Solutions
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• v.2 no.3
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• pp.52-61
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• 1999

The laser induced forward transfer(LIFT) technique employs a pulsed laser to transfer parts of a thin metal film from an optically transparent target onto an arbitrary substrate in close proximity to the metal film on the target. In this work, a two-step method, the combination of LIFT process, in which a Au film deposited on the $Al_2$O$_3$ substrate by Nd:YAG laser and subsequent Au electroless metal plating on the by LIFT process generated Au seed, was presented. The influence of laser parameters, wavelength, laser power, film thickness and overlap ratio of pulse tracks, on the shapes of deposit and conductor line after electroless plating is experimentally studied. As a results, the threshold power densities for ablation, deposition and metallization were determined and comparison of threshold value between the wave length 1064nm and the second harmonic generated 532nm. In odor to determine a possible application in the electronic industry, a smallest conduct spot size, line width and isolated line space were generated.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.216-220
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• 2000

AC Superconducting Generators (ACSG) are featured by 3D magnetic flux distribution, which decreases in the direction of axis. For this reason, when ACSG is optimal designed, 3D magnetic field analysis is required. This paper proposes 2D Finite Element Analysis (FEA) results normalized by 3D FEA according to the position of armature coil and the ratio of field coil width to axial length in order to reduce the analysis time. By using the proposed data, the reasonable 3D FEA results of ACSG can be only predicted by 2D FEA results. The validity of the 3D FEA results is verified by comparison with the experimental results of 30kVA superconducting synchronous generator.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.256-259
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• 2008

An micro-probe tip must be manufactured using thin film to evaluate integrity of the semiconductor with narrow distance between pads. In this study, fatigue tests were performed for BeCu thin film which is used in micro-probe tip of semiconductor test machine. The thin film was manufactured by electro plating process, and the specimens were fabricated by wire-cut electric discharge method to make hour glass type specimen of $5000{\mu}m$ width, $29200{\mu}m$ length and $30{\mu}m$ thickness. The fatigue test of load control with 10Hz frequency was performed, in ambient environment. The fatigue cycles were tension-tension with mean stress, at stress ratio, R=0.1.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.5
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• pp.411-418
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• 2008

In this work, the effect of strength mismatch on plastic limit loads is quantified for similar metal weld plates with cracks under tension load, via three-dimensional, small strain elastic-perfectly plastic finite element analyses. Relevant variables related to plate geometry and crack length are systematically varied, in addition to the weld width. An important finding is that mis-match limit loads can be uniquely quantified through strength mis-match ratio and one geometry-related parameter. Based on the proposed limit load solutions, reference stress based J-integral estimates is also investigated. When the reference stress is defined by the mis-match limit load, predicted J-integral values agree overall well with FE results.

• Geomechanics and Engineering
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• v.20 no.5
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• pp.385-397
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• 2020

This paper presents an application of artificial neural networks (ANNs) in settlement prediction of a foundation on sandy soil. In order to train the ANN model, a wide experimental database about settlement of foundations acquired from available literatures was collected. The data used in the ANNs model were arranged using the following five-input parameters that covered both geometrical foundation and sandy soil properties: breadth of foundation B, length to width L/B, embedment ratio D_f/B, foundation net applied pressure q_net, and average SPT blow count N. The backpropagation algorithm was implemented to develop an explicit predicting formulation. The settlement results are compared with the results of previous studies. The accuracy of the proposed formula proves that the ANNs method has a huge potential for predicting the settlement of foundations on sandy soils.

• International Journal of Contents
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• v.8 no.4
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• pp.95-102
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• 2012

In this paper, we present a technique to extract the title areas from book cover images. A typical book cover image may contain text, pictures, diagrams as well as complex and irregular background. In addition, the high variability of character features such as thickness, font, position, background and tilt of the text also makes the text extraction task more complicated. Therefore, we propose a two steps efficient method that uses Histogram of Oriented Gradients and color information to find the title areas. Firstly, text localization is carried out to find the title candidates. Finally, refinement process is performed to find the sufficient components of title areas. To obtain the best result, we also use other constraints about the size, ratio between the length and width of the title. We achieve encouraging results of extracted title regions from book cover images which prove the advantages and efficiency of the proposed method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.3
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• pp.259-266
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• 2004

Detailed two-dimensional and three-dimensional finite element (FE) analyses of double-edge cracked tension (DE(T)) specimens are carried out to investigate the effect of the relative crack length and the thickness on experimental J testing schemes. Finite element analyses involve systematic variations of relevant parameters, such as the relative crack depth and plate width-to-thickness ratio. Furthermore, the strain hardening index of material is systematically varied, including perfectly plastic (non-hardening) cases. Based on FE results, a robust experimental J estimation scheme is proposed.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.205-212
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• 2006

Three-dimensional numerical study was carried out for the investigation of the detonation wave structures propagating in tubes. Fluid dynamics equations and conservation equation of reaction progress variable were analyzed by a MUSCL-type TVD scheme and four stage Runge-Kutta time integration. Chemical reaction was modeled by using a simplified one-step irreversible kinetics model. The variable gas properties between unburned and burned states were considered by using variable specific heat ratio formulation. The unsteady computational results in three-dimension show the detailed mechanisms of rectangular and diagonal mode of detonation wave instabilities resulting same cell length but different cell width in smoked-foil record. The results for the small reaction constant shows the spinning mode of three-dimensional detonation wave dynamics, which was rarely observed in the previous numerical simulation of the detonation waves.

• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.101-105
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• 2020

Ralfsia longicellularis is known as an endemic species in Far East Asia. In this study, we report R. longicellularis as a new record from Korea based on morphological and molecular analyses. Molecular analyses based on plastid-encoded rbcL gene sequences and morpho-anatomical studies were undertaken on Ralfsia species, a poorly studied genus from Korea. Ralfsia longicellularis is mainly characterized by a dark brown thallus; 770-1200 ㎛ thick, curved cells in the creeping and ascending parts of the filaments; basal layer and erect filament cells with a width-to-length ratio of 1 : 1.5 to 10; narrowshaped sporangia on-stalk cells at the base of the paraphyses; and mostly uniseriate plurilocular reproductive organs capped with 1-2 sterile cells. The R. longicellularis samples from Korea in this study were similar to ones collected from the type locality (Peter the Great Bay, Russia) in morphology. The rbcL analyses also revealed that our Korean R. longicellularis samples were placed in the same clade with Russian materials, within a Ralfsia clade but distinct from the congeners.