• Journal of Ocean Engineering and Technology
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• v.35 no.5
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• pp.327-335
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• 2021

Microcracks can rapidly grow and develop in high-strength steels used in offshore structures. It is important to render these microcracks harmless to ensure the safety and reliability of offshore structures. Here, the dependence of the aspect ratio (As) of the maximum depth of harmless crack (a_hlm) was evaluated under three different conditions considering the threshold stress intensity factor (Δk_th) and residual stress of offshore structural steel F690. The threshold stress intensity factor and fatigue limit of fatigue crack propagation, dependent on crack dimensions, were evaluated using Ando's equation, which considers the plastic behavior of fatigue and the stress ratio. a_hlm by peening was analyzed using the relationship between Δk_th obtained by Ando's equation and Δk_th obtained by the sum of applied stress and residual stress. The plate specimen had a width 2W = 12 mm and thickness t = 20 mm, and four value of As were considered: 1.0, 0.6, 0.3, and 0.1. The a_hlm was larger as the compressive residual stress distribution increased. Additionally, an increase in the values of As and Δk_th(l) led to a larger a_hlm. With a safety factor (N) of 2.0, the long-term safety and reliability of structures constructed using F690 can be secured with needle peening. It is necessary to apply a more sensitive non-destructive inspection technique as a non-destructive inspection method for crack detection could not be used to observe fatigue cracks that reduced the fatigue limit of smooth specimens by 50% in the three types of residual stresses considered. The usefulness of non-destructive inspection and non-damaging techniques was reviewed based on the relationship between a_hlm, a_NDI (minimum crack depth detectable in non-destructive inspection), a_{cr N} (crack depth that reduces the fatigue limit to 1/N), and As.

• Wind and Structures
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• v.17 no.2
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• pp.227-244
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• 2013

Non-stationary extreme winds such as thunderstorm downbursts are responsible for many structural damages. This research presents a time domain approach for estimating along-wind load effects on tall buildings using multiple wind speed time history samples, which are simulated from evolutionary power spectra density (EPSD) functions of non-stationary wind fluctuations using the method developed by the authors' earlier research. The influence of transient wind loads on various responses including time-varying mean, root-mean-square value and peak factor is also studied. Furthermore, a simplified model is proposed to describe the non-stationary wind fluctuation as a uniformly modulated process with a modulation function following the time-varying mean. Finally, the probabilistic extreme response and peak factor are quantified based on the up-crossing theory of non-stationary process. As compared to the time domain response analysis using limited samples of wind record, usually one sample, the analysis using multiple samples presented in this study will provide more statistical information of responses. The time domain simulation also facilitates consideration of nonlinearities of structural and wind load characteristics over previous frequency domain analysis.

• Structural Engineering and Mechanics
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• v.45 no.5
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• pp.655-676
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• 2013

In this study, strength reduction factors and inelastic displacement ratios are investigated for SDOF systems with period range of 0.1-3.0 s considering soil structure interaction for earthquake motions recorded on soft soil. The effect of stiffness degradation on strength reduction factors and inelastic displacement ratios is investigated. The modified-Clough model is used to represent structures that exhibit significant stiffness degradation when subjected to reverse cyclic loading and the elastoplastic model is used to represent non-degrading structures. The effect of negative strain - hardening on the inelastic displacement and strength of structures is also investigated. Soil structure interacting systems are modeled and analyzed with effective period, effective damping and effective ductility values differing from fixed-base case. For inelastic time history analyses, Newmark method for step by step time integration was adapted in an in-house computer program. New equations are proposed for strength reduction factor and inelastic displacement ratio of interacting system as a function of structural period($\tilde{T}$, T) ductility (${\mu}$) and period lengthening ratio ($\tilde{T}$/T).

• Journal of Korea Foresty Energy
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• v.25 no.2
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• pp.49-54
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• 2006

This study was carried out to provide basic data for using domestic structural softwood lumber efficiently and ensuring structural safety of timber structures. The ratios (k-factor) between static and dynamic MOE measured by ultrasonic device for $2{\times}6$ domestic softwood structural lumber are 1.0602 for Korean red pine, 1.0013 for Korean white pine and 1.2320 for Japanese larch. In machine grade using nondestructive method, 76% of Korean red pine was classified into higher than E9 grade, 85% of Korean white pine was sorted into higher than E7 grade and 68% of Japanese larch was classified into higher than E11 grade. Correlation between MOE and MOR by static bending with k-factor from nondestructive method provide a possibility to predict bending strength and allowable stress of domestic softwood structural lumber.

• Journal of Microbiology and Biotechnology
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• v.29 no.8
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• pp.1184-1192
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• 2019

The influenza A virus is a highly infectious respiratory pathogen that sickens many people with respiratory disease annually. To prevent outbreaks of this viral infection, an understanding of the characteristics of virus-host interaction and development of an anti-viral agent is urgently needed. The influenza A virus can infect mammalian species including humans, pigs, horses and seals. Furthermore, this virus can switch hosts and form a novel lineage. This so-called zoonotic infection provides an opportunity for virus adaptation to the new host and leads to pandemics. Most influenza A viruses express proteins that antagonize the antiviral defense of the host cell. The non-structural protein 1 (NS1) of the influenza A virus is the most important viral regulatory factor controlling cellular processes to modulate host cell gene expression and double-stranded RNA (dsRNA)-mediated antiviral response. This review focuses on the influenza A virus NS1 protein and outlines current issues including the life cycle of the influenza A virus, structural characterization of the influenza A virus NS1, interaction between NS1 and host immune response factor, and design of inhibitors resistant to the influenza A virus.

• International Journal of Advanced Culture Technology
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• v.10 no.1
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• pp.97-101
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• 2022

The perceiving a calling scale is composed of three constructs: transcendent sermon, meaningful and prosocial aspects. Based on the multiple group confirmatory factor analysis from the structural equation model, we confirmed the measurement invariance between Christians and non-Christians at the scale level. Furthermore, to investigate the mean difference between Christians and non-Christians, we performed latent mean analysis. The results showed that the three-factor structure is equivalent across Christians and non-Christians, and further confirmed metric invariance and scalar invariance. Thus, the perceived calling scale is applicable to both Christians and non-Christians without biases. We also examined mean differences between the two groups. Christians demonstrated significantly higher scores on the three factors but no difference on the living a calling. This study provided meaningful information in understanding calling, and we discussed limitations and future directions.

• Structural Engineering and Mechanics
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• v.44 no.5
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• pp.681-704
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• 2012

The dynamic response of Euler-Bernoulli beams to resonant harmonic moving loads is analysed. The non-dimensional form of the motion equation of a beam crossed by a moving harmonic load is solved through a perturbation technique based on a two-scale temporal expansion, which permits a straightforward interpretation of the analytical solution. The dynamic response is expressed through a harmonic function slowly modulated in time, and the maximum dynamic response is identified with the maximum of the slow-varying amplitude. In case of ideal Euler-Bernoulli beams with elastic rotational springs at the support points, starting from analytical expressions for eigenfunctions, closed form solutions for the time-history of the dynamic response and for its maximum value are provided. Two dynamic factors are discussed: the Dynamic Amplification Factor, function of the non-dimensional speed parameter and of the structural damping ratio, and the Transition Deamplification Factor, function of the sole ratio between the two non-dimensional parameters. The influence of the involved parameters on the dynamic amplification is discussed within a general framework. The proposed procedure appears effective also in assessing the maximum response of real bridges characterized by numerically-estimated mode shapes, without requiring burdensome step-by-step dynamic analyses.

• Fibers and Polymers
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• v.7 no.2
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• pp.203-212
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• 2006

The purpose of this study was to examine the effects of the structural properties of plain knit fabrics on the subjective perception of textures, sensibilities, and preference among consumers. This study, then, aimed to provide useful information with respect to planning and designing knitted fabrics by predicting the subjective characteristics analyzed according to their structural properties. For this purpose, we employed statistical analysis tools, such as factor and regression analysis and an adaptive-network-based fuzzy inference system(ANFIS), thereby combining the merits of fuzzy and neural networks and presupposing a non-linear relationship. Through factor analysis, we also categorized the subjective textures into 'roughness', 'softness', 'bulkiness' and 'stretch-ability' with R2=70.32%: and categorized the sensibilities into 'Stable/Neat', 'Natural/Comfortable' and 'Feminine/Elegant' with R2=68.12%. We analyzed subjective textures, sensibilities, and preference with ANFIS, assuming non-linear relationships; consequently, we were able to generate three or four fuzzy rules using wool/rayon fiber content and loop length as input data. The textures of roughness and softness exhibited a linear relationship, but other subjective characteristics demonstrated a non-linear input-output relationship. Compared with linear regression analysis, the ANFIS exhibited had higher predictive power with respect to predicting subjective characteristics.

• Journal of Distribution Science
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• v.14 no.6
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• pp.99-106
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• 2016

Purpose - The antecedent to the relationship between the effect of the characteristics of strategic alliances and the performance of container liner shipping companies has been investigated in this study as container liner shipping companies' strategic alliances. It affects positively and negatively home, partner, and the third parties' performance in container liner shipping companies. Extensive literature reviews on shipper's strategic alliances reveal that strategic alliances in financial and non-financial performance of container liner shipping companies show the performance such as economic effects, business performance, global supply chain management performance, customer satisfaction, and forward integration and backward integration performance. The purpose of this study is to test empirically that the relationship between the characteristics of strategic alliances and financial and non-financial performance in container liner shipping companies. Structured equation modeling and confirmatory factor analysis were used to test the hypothesis using AMOS statistics program. Most previous researches focused on the relationship between the characteristics of strategic alliances and alliance types. There are few empirical studies that focus on business performance data because it is difficult to collect data in container liner shipping companies. However, this research measures financial and non-financial performance differently compared with the previous researches focusing on the characteristics of strategic alliances and alliance types measurements. Research design, data, and methodology - The conceptual model for the study is based on the studies of Lim (2010), Chen & Zhen (2009), and Wang & Meng (2014). The model is built around the factors of characteristics of strategic alliances and business performance. Cost, marketing, and service factors are regarded as proxy for the characteristics of strategic alliances. The financial and non-financial performance are regarded as proxy for the performance of strategic alliances. Based on the analysis of one hundred cases such as forwarder, shipper, and liner shipping companies, this study uses structural equation modeling to verify the effects of the characteristics of strategic alliances on business performance. Conclusions - This study provides container liner shipping companies to get some policy and practical implications in terms of the characteristics of strategic alliances and business performance. First, the cost factor for alliances characteristics has a positively significant influence on the financial and non-financial performance of strategic alliances. The cost factor relationship between high and low performance group does not have a significant difference on the performance of strategic alliances. Second, the marketing factor of alliances characteristics has a positively significant influence on the financial and non-financial performance of strategic alliances. The high performance group's marketing factor has a great non-financial performance than low performance group, but the low performance group's marketing factor has a grater financial performance than high performance group factor does. Third, the service factor of alliances characteristics has a negative influence on the non-financial performance of strategic alliances. The high performance group's service factor has a great non-financial performance than low performance group. Based on the findings from this study, related implications and future avenues deserve to be discussed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.4
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• pp.301-308
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• 2016

In this study, a novel method referred as non-marker vision-based displacement measuring system(NVDMS) was introduced in order to measure the displacement of structure. There are two distinct differences between proposed NVDMS and existing vision-based displacement measuring system(VDMS). First, the NVDMS extracts the pixel coordinates of the structure using a feature point not a marker. Second, in the NVDMS, the scaling factor in order to convert the coordinates of a feature points from pixel value to physical value can be calculated by using the external conditions between the camera and the structure, which are distance, angle, and focal length, while the scaling factor for VDMS can be calculated by using the geometry of marker. The free vibration test using the three-stories scale model was conducted in order to analyze the reliability of the displacement data obtained from the NVDMS by comparing the reference data obtained from laser displacement sensor(LDS), and the measurement of dynamic characteristics was proceed using the displacement data. The NVDMS can accurately measure the dynamic displacement of the structure without the marker, and the high reliability of the dynamic characteristics obtained from the NVDMS are secured.