• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1209-1211
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• 2003

The wavelet and semivariogram analysis method are used to identify the city landscape and farmland landscape pattern on the 1m resolution IKONOS images. The results prove that wavelet method is a potential way for landscape pattern analysis. Compared to semivariogram analysis, Wavelet analysis can not only detect the overall spatial pattern, but also find multi-scale and direction structures. In this experiment, the wavelet analysis results indicate: (1) the city landscape image is mainly composed of three level structures whose spatial pattern characters appear at 2m, 16m, 128m and 256m accordingly; (2) the farmland landscape is mainly two scale spatial patterns appearing at the 2m, 128m and 256m. IKONOS Remote sensing, with the high spatial and spectral information, is a powerful tool that can use in many ecological systems research and sustainable management.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.10
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• pp.911-916
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• 2015

In the nano/micro scale, material properties are dependent on the size-scale of a structure. However, conventional micro-scale tensile tests have limitations to obtain reliable values of nano-scale material properties owing to residual stress and elastic slippage in the gripping/aligning process. The indenter-driven nano-scale tensile test provides prominent advantages simple testing device, high-quality nano-scale metallic specimen with negligible residual stress. In this paper, two-types of specimens (a specimen with multi-testing parts and a specimen with a single-testing part) are discussed. Focused ion beam (FIB) is employed to fabricate a nano-scale specimen from a thin nickel film. Using the specimen with a single-testing part, we obtained a nano-scale stress-strain curve of electroplated nickel film.

• Journal of the Korean Institute of Educational Facilities
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• v.26 no.5
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• pp.25-36
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• 2019

School gymnasium is a multi-purpose large space building for various events and physical education activities, and is a facility that requires an approach to the desirable structural design, besides mechanical problems of structure against loads. For the integrated structure design concerning the architectural features, the major considerations of gymnasium planning that are the internal and external shape of the gymnasium, the space scale with structure members, the structural efficiency by members weight reduction and openness of the gymnasium space will have to take into account in the structural planning. From this point of view, the several cases of the school gymnasium were investigated and the parametric analyses were performed to the models using the various structural system. The parameters were the composition elements of structure system that are profile of structure, rigidity of member, connection and anchorage and stability. At the result, It was presented that the profile of structure member was the most influential factor to structural efficiency and the effect of the form and space of gymnasium. Also the design informations of structure design having the various feature of form and space were presented for the initial gymnasium planning.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.35.4-35.4
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• 2019

Understanding the interplay between galaxies and dark matter in the universe is one of key challenges in modern astrophysics. This provides an important test of structure formation scenarios and cosmological models. I discuss three aspects of this test: (1) comparing the matter distribution from galaxy redshift surveys with that from weak-lensing surveys, (2) statistical comparison of large-scale structures between observations and cosmological simulations, and (3) multi-wavelength study of galaxies. These tests underscore the importance of combining photometric and spectroscopic surveys in observations along with cosmological simulations for exploring and understanding the structure formation.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.135-136
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• 1998

By the ion bombardment the original discrete layered structure is damaged and a uniformly mixed layer is formed by the intermixing of the films. Immediately after this dynamic cascade mixing a structure of this mixed layer is likely to be a mixture of randomly distributed atoms. Subsequently the mixed layered structure becomes a non-equilibrium structure such as the metastable pphase because the kinetic energies of the incident ions rappidly dissippate and host atoms within the collision cascade region are quenched from a highly energetic state. The formation of the metastable transition metal alloys using ion-beam-mixing has been extensively studied for many years because of their sppecific ppropperties that differ from those of bulk materials. in ion-beam-mixing the alloy or comppound is formed due to the atomic interaction between different sppecies during ion bombardment. in this study the metastable pphase formed by ion-beam-mixing pprocess is comppared with equilibrium one by arc-melting method by GXRD and XAS. Therfore we studied the fundamental characteristics of charge redistribution uppon alloying and formation of intermetallic comppounds. The multi-layer films were depposited on a wet-oxidized Si(100) substrate by sequential electron beam evapporation at a ppressure of less than 5$\times$10-7 Torr during depposition. These compprise 4 ppairs of Co and ppt layers where thicknesses of each layer were varied in order to change the alloy compposition.

• Journal of the Korean Society of Safety
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• v.32 no.2
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• pp.72-77
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• 2017

In S. Korea, recently, building fire accidents of residential accommodations or recreational facilities have taken place more frequently than before. Among various building constructions, Multi-layered structure, such as office-residential complex, are mostly made in S. korea. $O_2$, $CO_2$, CO, $NO_x$, $SO_x$, and HCl, these gases has toxic hazard and harmful for human body. And it is predicted that different concentration of released gases from diesel pool fire with upper and lower layer. Therefore, this study reports the fire characteristics of Multi-layered structure by analyzing the fire behavior and concentration of combustion gases of a experimental compartment via real scale fire experiment, in order to predict risks and secure safety for similar fire accidents.

• Smart Structures and Systems
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• v.13 no.4
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• pp.501-515
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• 2014

This paper presents a linear computational homogenization framework to evaluate the effective (or generalized) electromechanical coupling coefficient (EMCC) of adaptive structures with piezoelectric structural fiber (PSF) composite elements. The PSF consists of a silicon carbide (SiC) or carbon core fiber as reinforcement to a fragile piezo-ceramic shell. For the micro-scale analysis, a micromechanics model based on the variational asymptotic method for unit cell homogenization (VAMUCH) is used to evaluate the overall electromechanical properties of the PSF composites. At the macro-scale, a finite element (FE) analysis with the commercial FE code ABAQUS is performed to evaluate the effective EMCC for structures with the PSF composite patches. The EMCC is postprocessed from free-vibrations analysis under short-circuit (SC) and open-circuit (OC) electrodes of the patches. This linear two-scale computational framework may be useful for the optimal design of active structure multi-functional composites which can be used for multi-functional applications such as structural health monitoring, power harvest, vibration sensing and control, damping, and shape control through anisotropic actuation.

• Structural Engineering and Mechanics
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• v.54 no.2
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• pp.239-256
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• 2015

An adaptive-scale damage detection strategy based on a wavelet finite element model (WFEM) for thin plate structures is established in this study. Equations of motion and corresponding lifting schemes for thin plate structures are derived with the tensor products of cubic Hermite multi-wavelets as the elemental interpolation functions. Sub-element damages are localized by using of the change ratio of modal strain energy. Subsequently, such damages are adaptively quantified by a damage quantification equation deduced from differential equations of plate structure motion. WFEM scales vary spatially and change dynamically according to actual needs. Numerical examples clearly demonstrate that the proposed strategy can progressively locate and quantify plate damages. The strategy can operate efficiently in terms of the degrees-of-freedom in WFEM and sensors in the vibration test.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.190-194
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• 1987

This paper describes a new method for control of large-scale system by sliding mode. The concepts of control to large-scale system on the basis of VSS(Variable Structure System) control theory are used to decompose a large control problem into a two-level algorithm such that each subsystem is stabilized with local discontinuous controllers and higher level corrective control is designed to take into account the effect of interaction among the subsystems. In this paper, we show that each subsystem is controlled with repect to local continuous and higher level corrective control. This algorithm can be easily applied to multi-variable control system and obtained a continuous control in comparison With variable structure control systems. Two numerical examples are discussed as illustrations.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.53.3-53.3
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• 2019

Recent work by Ravanbakhsh et al. (2017), Mathuriya et al. (2018) showed that convolutional neural networks (CNN) can be trained to predict cosmological parameters from the visual shape of the large scale structure, i.e. the filaments, clusters and voids of the cosmic density field. These preliminary works used the dark matter density field at redshift zero. We build upon these works by considering realistic mock galaxy catalogues that mimic true observations. We construct light-cones that span the redshift range appropriate for current and near future cosmological surveys such as LSST, EUCLID, WFIRST etc. In summary, we propose a novel multi-image input CNN to track the evolution in the morphology of large scale structures over cosmic time to constrain cosmology and the expansion history of the Universe.