• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.275-282
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• 2007

In this study, a fluid-structure interaction (FSI) analysis system has been developed in order to evaluate the turbine cascade performance with blade structural deformation effect. Relative movement of the rotor with respect to stator is reflected by modeling independent two computational domains. To consider the deformed position of rotor airfoil, dynamic moving grid method is applied. Reynolds-averaged Navier-Stokes equations with one equation Spalart-Allmaras and two-equation SST $k-{\varepsilon}$ turbulence models are solved to predict unsteady fluid dynamic loads. A fully implicit time marching scheme based on the Newmark direct integration method with high artificial damping is used to compute the fluid-structure interaction problem. Cascade performance evaluations for different elastic axis positions are presented and compared each other. It is importantly shown that the predicted aerodynamic performance considering structural deformation effect of blade can show some deviations compared to the data generally computed from rigid blade configurations and the position of elastic axis also tend to give sensitive effect.

• 한국염색가공학회지
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• 제31권4호
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• pp.298-311
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• 2019

In this study, the mechanical properties and hand characteristics of the knitted and woven fabrics for bedding items are investigated in accordance with fabric structural parameters including the fiber type and proportion, the density of the fabric, and the knit/weave structure. The knit stitches and structure of the knit samples made an effect on tensile properties. The bending, shear and compression properties for the knit fabric were mainly affected by fiber contents of the samples. The tensile and bending properties of woven samples were highly correlated with the fabric density, thickness and structure, and those shear and compression properties were affected by the fiber contents and structure. Consequently, the primary hand values of the selected samples we developed were estimated to have good smoothness, fullness and softness, and soft feeling, which is well correlated to the parameters of consumer preference such as softness, warmness, and bulkiness. Also, their total hand values were increased.

• Earthquakes and Structures
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• 제12권6호
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• pp.653-663
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• 2017

A seismic margin assessment evaluates how much margin exists for the system under beyond design basis earthquake events. Specifically, the seismic margin for the entire system is evaluated by utilizing a systems analysis based on the sub-system and component seismic fragility data. Each seismic fragility curve is obtained by using empirical, experimental, and/or numerical simulation data. The systems analysis is generally performed by employing a fault tree analysis. However, the current practice has clear limitations in that it cannot deal with the uncertainties of basic components and accommodate the newly observed data. Therefore, in this paper, we present a Bayesian-based seismic margin assessment that is conducted using seismic fragility data and fault tree analysis including Bayesian inference. This proposed approach is first applied to the pooltype nuclear research reactor system for the quantitative evaluation of the seismic margin. The results show that the applied approach can allow updating by considering the newly available data/information at any level of the fault tree, and can identify critical scenarios modified due to new information. Also, given the seismic hazard information, this approach is further extended to the real-time risk evaluation. Thus, the proposed approach can finally be expected to solve the fundamental restrictions of the current method.

• 한국지능시스템학회논문지
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• 제22권1호
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• pp.114-118
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• 2012

본 연구는 시스템의 구조 인식에 유효한 FSM을 이용하여 기업프로젝트 성과요인에 대한 층별 구조는 알 수 있지만 각 층에 속해 있는 성과요인에 대한 층별 간의 관계에 대해서는 알 수 없다는 관점에서 퍼지시스템을 이용하여 기업프로젝트 성과요인의 층별 관계에 대한 구조를 분석하고자 한다. 최하층과 중간층, 중간층과 최상층과의 관계를 가능적인 면과 필연적인 면이 섞여 있는 형태의 기업프로젝트 평가모델을 이용하여 구한 퍼지관계행렬로서 퍼지관계분석을 행하고 그 유용성을 보였다.

• Earthquakes and Structures
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• 제17권6호
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• pp.599-609
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• 2019

After an earthquake, a quick seismic assessment of a structure can facilitate the recovery of operations, and consequently, improve structural resilience. Especially for facilities that play a key role in rescue or refuge efforts (e.g., hospitals and power facilities), or even economically important facilities (e.g., high-tech factories and financial centers), immediately resuming operations after disruptions resulting from an earthquake is critical. Therefore, this study proposes a prompt post-earthquake seismic evaluation method that uses displacement and acceleration measurements taken from real structural responses that resulted during an earthquake. With a prepared pre-earthquake capacity curve of a structure, the residual seismic capacity can be estimated using the residual roof drift ratio and stiffness. The proposed method was verified using a 6-story steel frame structure on a shaking table. The structure was damaged during a moderate earthquake, after which it collapsed completely during a severe earthquake. According to the experimental results, a reasonable estimation of the residual seismic capacity of structures can be performed using the proposed post-earthquake seismic evaluation method.

• 대한기계학회논문집A
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• 제32권11호
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• pp.911-917
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• 2008

It was found that more than 60% of the steam turbine blade damages occurred under the condition alternatively repeated wet and dry of vapor and condensed vapor at the lower pressure stage. And also, it has been well known that both the mechanical properties and environmental strength of the steam turbine blade can be changed by the crystal structure. However, in spite of these common facts, it is difficult to find out the quantitative results including the particular environmental condition as well as the actual service conditions. In this study, as a fundamental investigation to provide design information and reliability evaluation of the 12Cr alloy steel used for a steam turbine blade, stress corrosion strength of the 12Cr alloy steel of which its crystal structure is different was assessed under $2.5{\sim}3.5wt.%$ NaCl solution at 90oC. From the results, S-t curves for predicting damage life and design criterion of the 12Cr alloy steel including corrosion environment as well as S.C.C. condition were obtained.

• Applied Microscopy
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• 제28권1호
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• pp.121-126
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• 1998

Detailed studies of high resolution TEM inages on the modulated structure caused by Zn vacancy ordering along [110] direction in BZT sintered at $1400^{\circ}C$ for 90 hours had revealed that the images which had hexagonal patterns were similar to those obtained from the structure which had no modulation, These images had appeared over the wide ranges from -30 nm to -42 nm in defocus values and from 2 nm to 20 nm in thickness. The computer simulated images showed that the modulation due to Zn vacancy ordering had made a small change in contrast in the interior of hexagonal pattern, which was very difficult to differenciate in experiments. The image which demonstrated the modulated structure very well was the one which obtained at -52 nm in defocus value and 16 nm in thickness.

• Computers and Concrete
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• 제32권5호
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• pp.475-486
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• 2023

Nondestructive evaluation (NDE) is an important task of civil engineering structure monitoring and inspection, but minor damage such as small cracks in local structure is difficult to observe. If cracks continued expansion may cause partial or even overall damage to the structure. Therefore, monitoring and detecting the structure in the early stage of crack propagation is important. The crack detection technology based on machine vision has been widely studied, but there are still some problems such as bad recognition effect for small cracks. In this paper, we proposed a deep learning method based on sweep signals to evaluate concrete surface crack with a width less than 1 mm. Two convolutional neural networks (CNNs) are used to analyze the one-dimensional (1D) frequency sweep signal and the two-dimensional (2D) time-frequency image, respectively, and the probability value of average damage (ADPV) is proposed to evaluate the minor damage of structural. Finally, we use the standard deviation of energy ratio change (ERVSD) and infrared thermography (IRT) to compare with ADPV to verify the effectiveness of the method proposed in this paper. The experiment results show that the method proposed in this paper can effectively predict whether the concrete surface is damaged and the severity of damage.

• 한국문헌정보학회지
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• 제47권2호
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• pp.103-121
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• 2013

이 연구는 미국의 사서교사 전문성과 관련된 기본 배경을 이해하고, 현재 미국에서 활용되고 있는 국가 수준과 주정부 수준의 사서교사 평가기준과 도구 그리고 자기평가 도구를 분석하는 것을 주요 목적으로 설정하고 있다. 연구결과는 다음과 같다. 미국은 국가 수준의 학교도서관 기준에 맞추어 사서교사 양성, 자격기준, 평가기준의 일관성 있는 전문성 계발 구조를 갖추었으며, 국가 수준의 사서교사 전문성 기준은 미국 전문교사자격 기준위원회의 자격기준과 미국학교도서관협회에서 발표한 "평생교육을 위한 학습" 기준의 사서교사 평가도구가 대표적으로 제시되고 있다. 미국의 여러 주정부에서는 국가 수준의 학교도서관 기준을 바탕으로 주정부의 실정에 맞는 사서교사 평가기준과 도구를 개발하여 실제 평가에 활용하고 있다. 더불어 미국학교도서관협회는 2012년에 사서교사의 자기평가 도구인 "사서교사 평가의 21세기 접근법"을 발표하여, 사서교사가 국가수준의 기준에서 제시한 전문성에 도달할 수 있는 실천적 방향을 안내하고 있다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제27권2호
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• pp.134-147
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• 2000

국.내외적으로 소프트웨어 산업이 활성화되었음에도 불구하고, 정보보호 소프트웨어 시스템의 보안성 평가를 포함한 각종 소프트웨어의 품질 평가 업무량 및 평가 비용 산정에 대한 연구는 부족하다. 본 연구에서는 업무분해구조(EWBS) 방법과 기존의 소프트웨어 개발비 산정 방법을 응용하여, 정보보호 시스템의 평가기준(Common Criteria 또는 ISO/IEC 15408)에 따라 정보보호 시스템을 평가 할 때의 평가 업무량과 평가 비용을 산정하는 프로세스와 도구를 제시한다. 본 연구는 정보보호 시스템의 평가 업무량과 평가 비용의 산정에 중심을 두고 있지만, 본 연구의 결과는 기존의 소프트웨어 개발 프로세스 및 제품의 품질 평가시의 평가 업무량 및 평가 비용의 산정에도 응용될 수 있다.