• Structural Engineering and Mechanics
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• 제83권6호
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• pp.729-744
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• 2022

In this paper, an analytical formulation is proposed to predict the vertical vibration response due to the pedestrian walking on a footbridge considering the human-structure interaction, where the footbridge and pedestrian are represented by the Euler beam and linear oscillator model, respectively. The derived coupled equation of motion is a nonlinear fourth-order partial differential equation. An uncoupled solution strategy based on the combined weighted residual and perturbation method) is proposed to reduce the tedious computation, which allows the separate integration between the bridge and pedestrian subsystems. The theoretical study demonstrates that the pedestrian subsystem can be treated as a structural system with added mass, damping, and stiffness. The analysis procedure is then applied to a case study under the conditions of single pedestrian and multi pedestrians, and the results are validated and compared numerically. For convenient vibration design of a footbridge, the simplified peak acceleration formula and the idea of decoupling problem are thus proposed.

• Asia Marketing Journal
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• 제22권1호
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• pp.27-39
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• 2020

Building on the growing literature on how physical bodily expressions influence psychological processes, the authors propose that exerting physical strength decreases risk perceptions and increases preference for risky options by increasing perceptions of control or agency. The present research is based on the belief of "no pain, no gain", that when an individual exerts physical strength and effort, he believes he can be the agent in bringing about the desired outcome. Because of this automatic association between exerting physical strength and the sense of being in control of the outcome, the authors hypothesize that even in situations where the outcome is determined by chance and luck, individuals exerting effort feel they have more control and thus choose riskier, but more desirable, options. Furthermore, this research clarifies the distinction between physical exertion of strength, high- and low-power poses, and psychological power.

• Nutritional Sciences
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• 제2권2호
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• pp.113-118
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• 1999

Critical evaluation of energy intake data from dietary studies is difficult but important. To investigate the underreporting of total energy intake, we analyzed the one-day dietary intake data collected by 24-hour recall method from 550 elderly Koreans aged 60 years or older. Underreporting was addressed by computing the ratio of energy intake (EI) to estimated basal metabolic rate (BMRest). EI : BMRest ratio was found to be 1.38 for, men and 1.33 for women, with about 14% of men and women classified as underreporters. Underreporting of energy intake was highest in men and women who were overweight, had lower family income, or no school education. For men, the most significant variables to predict the ratio of energy intake to estimated basal metabolic. rate (EI : BMRest) were weight status, members of household, alcohol consumption and age, while income and education level were most significant for women.

• 대한인간공학회지
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• 제14권1호
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• pp.69-81
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• 1995

Few studies on the biomechanical analysis of hand postures and tool handling tasks exist because of the lack of appropriate measurement techniques for hand force. A measurement system for the finger forces and joint angles for the analysis of manual tool handling tasks was developed in this study. The measurement system consists of a force sensing glove made from twelve Force Sensitive Resistors and an angle-measuring glove (Cyberglove$^{TM}$, Virtual technologies) with eighteem joint angle sensors. A biomechanical model of the hand using the data from the measurement system was also developed. Systems of computerized procedures were implemented inte- grating the hand posture measurement system, biomechanical analysis system, and the task analysis system for manual tool handling tasks. The measurement system was useful in providing the hand force data needed for an existing task analysis system used in CTD risk evaluation. It is expected that the hand posture measurement developed in this study will provide an efficient and cost-effective solution to task analysis of manual tool handling tasks.s.

• The Plant Pathology Journal
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• 제39권6호
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• pp.538-547
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• 2023

Rapid apple decline (RAD) is a complex phenomenon affecting cultivated apple trees and particularly dwarf rootstocks on grafted young apple trees. Since its first appearance in the United States, RAD has been reported worldwide, for example in Canada, South America, Africa, and Asia. The phenomenon has also been observed in apple orchards in Korea, and it presented similar symptoms regardless of apple cultivar and cultivation period. Most previous reports have suggested that RAD may be associated with multiple factors, including plant pathogenic infections, abiotic stresses, environmental conditions, and the susceptibility of trees to cold injury during winter. However, RAD was observed to be more severe and affect more frequently apple trees on the Malling series dwarf rootstock. In this study, we reviewed the current status of RAD worldwide and surveyed biotic and abiotic factors that are potentially closely related to it in Korea.

• Journal of Microbiology
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• 제44권5호
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• pp.548-555
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• 2006

FaeG is the key factor in the infection process of K88ad enterotoxigenic Escherichia coli (ETEC) fimbrial adhesin. In an attempt to determine the possibility of expressing recombinant FaeG with immunogenicity for a new safe and high-production vaccine in E. coli, we constructed the recombinant strain, BL21 (DE3+K88), which harbors an expression vector with a DNA fragment of faeG, without a signal peptide. Results of 15% SDS-polyacrylamide slab gel analysis showed that FaeG can be stably over-expressed in BL21 (DE3+K88) as inclusion bodies without FaeE. Immunoglobulin G (IgG) and M (IgM) responses in pregnant pigs, with boost injections of the purified recombinant FaeG, were detected 4 weeks later in the sera and colostrum. An in vitro villius-adhesion assay verified that the elicited antibodies in the sera of vaccinated pigs were capable of preventing the adhesion of K88ad ETEC to porcine intestinal receptors. The protective effect on the mortality rates of suckling piglets born to vaccinated mothers was also observed one week after oral challenge with the virulent ETEC strain, $C_{83907}$ (K88ad, $CT^+,\;ST^+$). The results of this study proved that the adhesin of proteinaceous bacterial fimbriae or pili could be overexpressed in engineered E. coli strains, with protective immune responses to the pathogen.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.138-141
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• 2004

[ $MnO_2$ ]가 첨가된 $0.9Pb(Zr_{0.5}Ti_{0.5})O_3-0.2Pb[(Zn_{0.8}Ni_{0.2})_{1/3}Nb_{2/3}]O_3$(0.8PZT-0.2PZNN) 세라믹스는 그 압전특성과 유전특성이 뛰어나지만 $1000^{\circ}C$ 이하의 낮은 소결 온도에서는 소결되지 않는다. $1000^{\circ}C$이하의 낮은 소결온도에서 소결하기 위해 CuO를 첨가한 결과, 소결온도 $920^{\circ}C$에서 소결성은 우수하였으나 그 압전 특성의 저하가 두드러졌다. 이는 XRD에서 확인한 결과에 따르면 CuO의 첨가가 우수한 MPB 조성으로 판명된 $MnO_2$ 가 첨가된 0.8PZT-0.2PZNN 세라믹스의 결정구조를 Rhombohedral 구조로 바꾸기 때문인 것으로 보였으며 이러한 문제는 PZNN의 비율을 조절하여 0.875PZT-0.125PZNN 세라믹스를 선택함으로 인해 해결할 수 있었다. 그러나 여전히 낮은 $Q_m$값을 높이기 위해서 $Al_2O_3$를 첨가하였고 그 결과 시편의 tetragonality 감소와 $Q_m$값의 증가를 확인할 수 있었으나 그 첨가량이 0.2wt% 이상일 경우에는 밀도의 감소로 인한 압전특성의 저하가 나타났다. 밀도의 향상을 위해 Zn and Ni excess 조성을 선택하였고 그 결과 0.5wt% $MnO_2$와 0.2wt% CuO 그리고 0.3wt% $Al_2O_3$를 첨가한 0.875PZT-0.125PZNN 세라믹스(Zn and Ni excess 조성)를 $920^{\circ}C$에서 소결한 경우 $k_p=0.581,\;Q_m=809,\;d_{33}=345\;pC/N\;and\;{\varepsilon}_{33}/{\varepsilon}_0=1345$의 빼어난 압전 및 유전특성과 $330^{\circ}C$의 높은 $T_c$를 보였고 그 조성의 vibration velocity는 약4.5 m/s로 나타났다.

• International Journal of Concrete Structures and Materials
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• 제8권2호
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• pp.129-139
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• 2014

In this study, the concrete fracture energy was obtained using the three point notched beam test method developed by Hillerborg et al. (Cem Concr Res 6(6):773-782, 1976). A total of 12 notched concrete beams were tested under two different loading conditions: constant stroke control and constant crack mouth opening displacement (CMOD) control. Despite individual fracture energies obtained from the two different loading conditions showing some variation, the average fracture energy from both loading conditions was very similar. Furthermore, the results obtained support the idea that a far tail constant "A" could change the true fracture energy by up to 11 %, if it is calculated using CMOD instead of LVDT. The far tail constant "A" is determined using a least squares fit onto a straight line according to Elices et al. (Mater Struct 25(148):212-218, 1992) and RILEM report (2007). It was also observed that the selection of the end point can produce variations of the true fracture energy. The end point indicates the point in the experiment at which to stop. An end point of 2 mm has been recommended, however, in this study other end points were also considered. The final form of the bilinear softening curve was determined based on Elices and Guinea's methods (1992, 1994) and RILEM report (2007). This paper proposes a bilinear stress-crack opening displacement curve according to test results as well as the CEB-FIP model code.

• 전기학회논문지
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• 제63권4호
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• pp.546-550
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• 2014

In this research, we report all the elements are placed in the space above the patient table as a transmit coil to give optimized B1+ field for the body object. Through the simulations, we compared upper-and-lower parts combined 8 channel Tx array to upper only 8 channel Tx array and showed the utilities of B1+ shimming in multi-channel Tx body imaging at 3T. Half-cylinder shaped upper array shows weak B1+ field area around back of patient without B1+ shimming. After B1+ shimming, highly induced SAR places occurred in the arm region due to the close distance to the both end elements which were driven by very high RF current to enhance B1+ in back area. The proposed upper and lower combined array provides an enhanced homogeneous B1+ field in large ROI imaging as a result of shimming over the body size phantom. Through this research we proved the usefulness of the proposed insertional upper and lower parts combined transmit array for 3T body imaging.

• Steel and Composite Structures
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• 제37권4호
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• pp.391-404
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• 2020

Human-induced vibration could present a serious serviceability problem for large-span and/or lightweight floors using the high-strength material. This paper presents the results of heel-drop, jumping, and walking tests on a large-span composite steel rebar truss-reinforced concrete (CSBTRC) floor. The effects of human activities on the floor vibration behavior were investigated considering the parameters of peak acceleration, root-mean-square acceleration, maximum transient vibration value (MTVV), fundamental frequency, and damping ratio. The measured field test data were validated with the finite element and theoretical analysis results. A comprehensive comparison between the test results and current design codes was carried out. Based on the classical plate theory, a rational and simplified formula for determining the fundamental frequency for the CSBTRC floor is derived. Secondly, appropriate coefficients (β_rp) correlating the MTVV with peak acceleration are suggested for heel-drop, jumping, and walking excitations. Lastly, the linear oscillator model (LOM) is adopted to establish the governing equations for the human-structure interaction (HSI). The dynamic characteristics of the LOM (sprung mass, equivalent stiffness, and equivalent damping ratio) are determined by comparing the theoretical and experimental acceleration responses. The HSI effect will increase the acceleration response.