• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.47-52
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• 2018

In this study, the effects of the heat treatment and multi-scale hierarchical structures on the durability of the nano-patterned functional PMMA(Poly(methyl-methacrylate)) film was evaluated. The heat treatments that consisted of high-pressure/high-temperature flat pressing and rapid cooling process were employed to improve mechanical property of the PMMA films. Multi-scale hierarchical structures were fabricated by thermal nanoimprint to protect nano-scale structures from the scratch. Examination on surface structures and functionalities such as wetting angle and transmittance revealed that the preopposed heat treatment and multi-scale hierarchical structures are effective to minimize surface damages.

• Composites Research
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• v.27 no.2
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• pp.66-71
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• 2014

This study carried out finite element vibration analysis of pole structures made of GFRP, which is based on the micro-mechanical approach for different fiber-volume fractions. The finite element (FE) models for composite structures using multi-scale approaches described in this paper is attractive not only because it shows excellent accuracy in analysis but also it shows the effect of the material combination. The FE model is used for studying free vibrations of laminated composite poles for various fiber-volume fractions. In particular, new results reported in this paper are focused on the significant effects of the fiber-volume fraction for various parameters, such as fiber angles, layup sequences, and length-thickness ratios. It may be concluded from this study that the combination effect of fiber and matrix, largely governing the dynamic characteristics of composite structures, should not be neglected and thus the optimal combination could be used to design such civil structures for better dynamic performance.

• Journal of Korea Multimedia Society
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• v.3 no.4
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• pp.339-346
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• 2000

Medical image is analyzed to get an anatomical information for diagnostics. Segmentation must be preceded to recognize and determine the lesion more accurately. In this paper, we propose automatic segmentation algorithm for MR brain images using T1-weighted, T2-weighted and PD images complementarily. The proposed segmentation algorithm is first, extracts cerebrum images from 3 input images using cerebrum mask which is made from PD image. And next, find 3D clusters corresponded to cerebrum tissues using scale filtering and 3D clustering in 3D space which is consisted of T1, T2, and PD axis. Cerebrum images are segmented using FCM algorithm with its initial centroid as the 3D cluster's centroid. The proposed algorithm improved segmentation results using accurate cluster centroid as initial value of FCM algorithm and also can get better segmentation results using multi spectral analysis than single spectral analysis.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.69-76
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• 2024

The rheological properties of fresh concrete significantly influence its manufacturing and performance. However, the diversification of newly developed mixtures and manufacturing techniques has made it challenging to accurately predict these properties using traditional empirical methods. This study introduces a multiscale rheological property prediction model designed to quantitatively anticipate the rheological characteristics from nano-scale interparticle interactions, such as those among cement particles, to micro-scale behaviors, such as those involving fine aggregates. The Yield Stress Model (YODEL), the Chateau-Ovarlez-Trung equation, and the Krieger-Dougherty equation were utilized to predict the yield stress for cement paste and mortar, as well as the plastic viscosity. Initially, predictions were made for the paste scale, using the water-cement ratio (W/C) of the cement paste. These predictions then served as a basis for further forecasting of the rheological properties at the mortar scale, incorporating the same W/C and adding the cement-sand volume ratio (C/S). Lastly, the practicality of the predictive model was assessed by comparing the forecasted outcomes to experimental results obtained from rotational rheometer.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.1
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• pp.29-34
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• 2012

Wireless multicast service can be used for video streaming service to save the network resources by sending the same popular multimedia contents to a group of users at once. For better multimedia streaming multicast service, we propose a quality-aware rate adaptation (QARA) scheme for scalable video multicast in rate adaptive wireless networks. In QARA, transmission rate is determined depending on the content's type and users' channel conditions. First, the base layer is transmitted by a low rate for high reliability. That means we provide basic service quality to all users. On the contrary, the transmission rate for enhancement layer is adapted by using channel condition feedback from a randomly selected node. So, the enhancement layer frames in a multimedia content is sent with various transmission rates. Therefore, each node can be provided with differentiated quality services. Consequently, QARA is capable of serving heterogeneous population of mobile nodes. Moreover, it can utilize network resources more efficiently. Our simulation results show that QARA outperforms utilization of the available transmission rate and reduces the data transmission time.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.4
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• pp.315-321
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• 2012

In this study, a sequential multiscale homogenization method to characterize the effective thermal conductivity of nano particulate polymer nanocomposites is proposed through a molecular dynamics(MD) simulations and a finite element-based homogenization method. The thermal conductivity of the nanocomposites embedding different-sized nanoparticles at a fixed volume fraction of 5.8% are obtained from MD simulations. Due to the Kapitza thermal resistance, the thermal conductivity of the nanocomposites decreases as the size of the embedded nanoparticle decreases. In order to describe the nanoparticle size effect using the homogenization method with accuracy, the Kapitza interface in which the temperature discontinuity condition appears and the effective interphase zone formed by highly densified matrix polymer are modeled as independent phases that constitutes the nanocomposites microstructure, thus, the overall nanocomposites domain is modeled as a four-phase structure consists of the nanoparticle, Kapitza interface, effective interphase, and polymer matrix. The thermal conductivity of the effective interphase is inversely predicted from the thermal conductivity of the nanocomposites through the multiscale homogenization method, then, exponentially fitted to a function of the particle radius. Using the multiscale homogenization method, the thermal conductivities of the nanocomposites at various particle radii and volume fractions are obtained, and parametric studies are conducted to examine the effect of the effective interphase on the overall thermal conductivity of the nanocomposites.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.1
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• pp.51-58
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• 2021

In this paper, a multi-scale finite element (FE) modeling methodology for three-dimensional (3D) needle-punched (NP) C/SiC with a complex microstructure is presented. The variations of the material properties induced by the needle-punching process and complex geometrical features could pose challenges when estimating the material behavior. For considering these features of composites, a 3D microscopic FE approach is introduced based on micro-CT technology to produce a 3D high fidelity FE model. The image processing techniques of micro-CT are utilized to generate discrete-gray images and reconstruct the high fidelity model. Furthermore, a subcell modeling technique is developed for the 3D NP C/SiC based on the high fidelity FE model to expand to the macro-scale structural problem. A numerical homogenization approach under periodic boundary conditions (PBCs) is employed to estimate the equivalent behavior of the high fidelity model and effective properties of subcell components, considering geometry continuity effects. For verification, proposed models compare excellently with experimental results for the mechanical behavior of tensile, shear, and bending under static loading conditions.

• Journal of Information Management
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• v.34 no.4
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• pp.43-61
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• 2003

The aim of this article is to study the new searching tool for era of multimedia. Thesaurus is a useful tool but is constituted with noun phrase including the adjective for retrieving the human Sensibility. Therefore, I experimentally construct the Sensibility thesaurus using the color scale which contains the Sensibility meanings. Terms are 261, Relation standards are distance and ratio of reiteration between the terms. I would use an exclusive program of the thesaurus construction for Sensibility adjective.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.11a
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• pp.190-192
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• 2013

최근 HD(High Definition)화질 및 UHD(Ultra High Definition)화질과 같은 고품질 방송 서비스가 등장하고, 무선 네트워크 기술의 발달로 스마트폰, 태블릿PC 등과 같은 다양한 휴대용 멀티미디어 기기들이 존재함에 따라, 소비자들은 다양한 환경에서 고해상도 영상을 고품질로 사용하기를 원하고 있다. 따라서 스케일러빌러티의 현실적 필요성이 점점 대두되고 있으며, 이에 따라 ISO/IEC의 MPEG(Moving Picture Experts Group)와 ITU-T의 VCEG(Video Coding Experts Group)이 공동으로 결성한 Joint Collaborative Team on Video Coding(JCT-VC)에 의해 시간, 공간, 화질 등이 확장성을 제공하는 Scalable Video Coding(SVC)의 표준화가 진행되고 있다. 이에 본 논문은 공간적, 시간적, 화질적 스케일러빌러티(Scalability)를 제공하기 위한 SHVC의 표준 기술들에 대해 설명하고, 기존 단일 계층 부호화 방식(Single Video Coding)으로 서로 다른 해상도의영상을 Simulcast부호화한 결과와 비교하여 SHVC의 부호화한 결과와 비교하여 SHVC의 보호화 효율에 대한 성능을 분석 하였다.

• Prospectives of Industrial Chemistry
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• v.22 no.4
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• pp.13-19
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• 2019

최근 가공할만한 성능의 슈퍼컴퓨터에 머신 러닝 기법을 연동한 인공 지능형 소재 정보학이 과학 기술 및 산업계에 새로운 연구개발 패러다임으로 급속히 확산되고 있다. 본 기고문에서는 이 기법의 성공에 핵심적 요소인 정확한 데이터베이스 구축을 위해 제일원리 전산을 적용하는 것과 이를 기반으로 소재를 구성하는 원소 간 인공 신경망 포텐셜을 만드는 방법을 소개하고자 한다. 이 연구 방법론은 나노 스케일 신소재 개발에 적용할 경우, 양자역학 수준의 정밀도로 순수 제일원리 전산 대비 100배 이상의 빠른 결과를 도출할 가능성이 있음을 예시한다. 이는 향후 다양한 산업계에 막대한 파급효과를 가져올 것으로 예상된다.