• Title/Summary/Keyword: Cross effects

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An Optimal Design of Cross Beam of P.S.C Girder Bridge (P.S.C거더 교량의 적정 가로보 설계)

  • 최창근;김경호;이계희
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2000.04b
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    • pp.389-396
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    • 2000
  • A three-dimensional finite element dynamic analysis was conducted to evaluate the effects of reducing cross beams from a simply supported straight P.S.C girder bridge. Two analyses were performed on the P.S.C girder bridge; one with 7 cross beams which is commonly used as current standard, and the other with 3 cross beams. A frequency analysis was conducted first in order to establish the dynamic characteristics of the bridge and determine an appropriate time step to use in the time history analyses. To assess the function and effectiveness of the cross beams, time history analysis was conducted for aforementioned two analysis cases. In the analysis, the complete model was subjected to a loading condition corresponding to the one passing truck loading. Several results of deflection, bending moment and shear forces were compared for two cases. From the analysis results, reduction of cross beams was found to have only a minimum effect on the response of the bridge. The maximum deck slab bending moment was found to decrease. This decrease should result in smaller flexural crack widths in the deck slab, which may lead to an improved deck performance.

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Numerical Experiments for the Optimization of the Flow Path through a Cross-Flow Fan (횡류팬 유로최적화를 위한 수치실험)

  • Jun, Yong-Du;Lee, Jong-Soo
    • 유체기계공업학회:학술대회논문집
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    • 2002.12a
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    • pp.147-151
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    • 2002
  • Cross flow fan system is widely used for various applications, especially for the air-moving device of heaters, air-conditioners, and air-curtains. Although there are efforts for the optimization of cross-flow fan flow path with different methods of approach, it is still being investigated by many researchers through experimentally and/or theoretically, because the flow pattern of the cross flow fan is not stereotyped. This paper presents some results from numerical experiments for the optimization of the flow path through a cross-flow fan to be applied to indoor wall-mounted room heater. Two dimensional analysis has been applied to a specific fan system including inlet and diffuser outlet. Flow characteristics art presented and discussed for two different flow path at three different operating conditions represented by rotational speed(800, 1,000, 1,200 rpm) of the In. According to the simulated results for the specific fan system under consideration, it could be found that the flow pattern resembles each other at different rotational speed (to say from 800 rpm to 1,200 rpm) for a fixed flow path, while the secondary flows mostly absorbs the speed effects. By changing the flow path significant increase in volume flow rate is estimated upto 2.65 at the same rotational speed. According to the present experience, fan flow path design can be performed more efficiently by incorporating this type of numerical experiments combined with the model tests.

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Effective α-Helix Stabilization via Hexenyl Propionate Cross-Link

  • Yoo, Jiyeon;Kim, Young-Woo
    • Bulletin of the Korean Chemical Society
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    • v.35 no.12
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    • pp.3627-3631
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    • 2014
  • In this study we examined two ester-containing cross-links, hex-2-enyl acetate and hex-2-enyl propionate, as new cross-linking systems for helix stabilization of short peptides. We demonstrated that these hexenyl ester cross-links can be readily installed via a ruthenium-mediated ring-closing metathesis reaction of L-aspartic acid 4-allyl ester or L-glutamic acid 5-allyl ester at position i and (S)-2-(4'-pentenyl)alanine at position i+4 using second generation Hoveyda-Grubbs catalyst at $60^{\circ}C$. Between these two cross-links, we found that the hex-2-enyl propionate significantly stabilizes the ${\alpha}$-helical conformations of short model peptides. The helix-stabilizing effects of the hex-2-enyl propionate tether appear to be as powerful as Verdine's i,i+4 all-hydrocarbon stapling system, which is one of the most widely used and the most potent helix-stabilizing cross-linking systems. Furthermore, the hex-2-enyl propionate bridge is reasonably robust against non-enzymatic hydrolytic cleavage at a physiological pH. While extended studies for probing its chemical scopes and biological applications are needed, we believe that this new helix-stabilizing system could serve as a useful chemical tool for understanding protein folding and designing conformationally-constrained peptide drugs.

Sound Characteristics according to Cross-sectional Shapes of Fibers

  • Kim, Chunjeong;Cho, Gilsoo;Hong, Kyoung A.;Shim, Hyun Joo
    • Fibers and Polymers
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    • v.4 no.4
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    • pp.199-203
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    • 2003
  • In order to investigate the effects of cross-sectional shapes on the sound characteristics of polyester fibers, 10 specimens were woven into a twill structure made of round, hollow, triangular, u-shape, cruciform, and composite cross-sectional (▲/▲ ,()/▲, Y/Y) fibers. Their rustling sounds were recorded, and their sound spectra were obtained from FFT analysis. Physical sound parameters (LPT, ΔL, Δf) and Zwicker's psychoacoustic parameters of the loudness(Z), sharpness(Z), roughness(Z), and fluctuation strength(Z) were calculated from the sound spectra. According to noncircular cross-section fibers, the hollow shaped fiber had the highest value of LPT, ΔL, loudness(Z), and fluctuation strength(Z). The triangular shaped fiber had a lower value of LPT, ΔL, loudness(Z), and roughness(Z) than those of the round shaped fiber. Among composite cross-section fibers, C1(▲/▲) and C3 (Y/Y) had higher values of LPT, ΔL, Δf and loudness(Z) but C2(()/▲) had lower values. Also the LPT, ΔL, sharpness(Z), and roughness(Z) values of different denier were similar to each other, but the Δf and loudness(Z) values increased as the denier increased.

Design of the Cross Sectional Shape of Intermediate Die for Shaped Drawing of Spline (스플라인 이형인발을 위한 중간 다이 단면형상 설계)

  • Lee, J.E.;Lee, T.K.;Lee, S.K.;Kim, B.M.
    • Transactions of Materials Processing
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    • v.17 no.8
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    • pp.627-632
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    • 2008
  • The cross sectional shape of intermediate die is one of important parameters to improve dimensional accuracy of final product in shaped drawing process. Until now, it has been designed by the experience or trial and error of the expert. In this study, the cross sectional shape of intermediate die for spline shape is determined by the electric fields analysis and scale factor method. The result of the electric fields analysis and scale factor method have been compared with that of the expert method. The effects of cross sectional shape on the dimensional accuracy were investigated by using FE-simulation. And then the multi-stage shaped drawing experiments were performed to verify the results of FE-simulation. As a result, the cross sectional shape from the electric fields analysis and scale factor method had the good dimensional accuracy. These two methods can be used for the method to obtain the cross sectional shape of intermediate die in shaped drawing process.

Preparation and Characterization of Pore-filled Membrane Based on Polypropylene with Poly(vinylbenzyl chloride) by Using in-situ Cross-linking Technique

  • Kwon, Byeong-Min;Ko, Moon-Young;Hong, Byung-Pyo;Byun, Hong-Sik
    • Korean Membrane Journal
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    • v.10 no.1
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    • pp.13-19
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    • 2008
  • Water softening is a very promising field for membranes and especially ultra low pressure membranes. Nanofiltration membranes based on pore-filling technology was prepared by using a new technique: the in-situ cross-linking. This route involves introducing a pre-formed polymer into the pores of a host membrane and then locking the polymer in the pores by in-situ cross-linking with an appropriate reagent. By this way, it is possible to make robust and competitive, pore-filled, anion-exchange membranes with excellent control over the properties of the incorporated gel without affecting the host membrane. In this paper, the possibilities of tuning such membranes for ultra low pressure water softening was examined by altering pore-filling chemistry (by changing cross-linking and aminating reagents). The results showed that tuning the chemistry of the pore-filling has important effects. In particularly, it had been shown that the correct selection of cross-linking reagent was not only essential to get pore-filled membranes but it could control their properties. Moreover, the aminating reagent could improve membrane performance. It was found that an increase in hydrophobicity could improve the Darcy permeability.

Integrity Test of DCM Treated Soils with a Cross-hole Sonic Logging (시추공간 음파검층법을 이용한 심층혼합 개량지반의 건전도 조사)

  • 김진후;조성경
    • Journal of Ocean Engineering and Technology
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    • v.15 no.1
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    • pp.73-78
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    • 2001
  • Soundness evaluation of a structure being constructed under the sea is usually difficult. In this study, a cross-hole sonic logging(CSL) which have been used for non-destructive test of concrete piles is adopted for the integrity test and monitoring of DCM(deep cement mixing) treated soils. Chemical and physical characteristics of raw ground materials are analysed to delineate ground environmental effects on the strength of DCM treated soils. In order to convert cross-hole sonic logging data into compressive strength, correlations between compressive strengths and wave velocities of core samples have been obtained. It is found that there is little effect of ground environment on the strength of the DCM treated soils, and the density distribution of core samples and cross-hole logging data show that a defective zone may exist in the DCM treated soils. With the time lapse, however, the defective zone has been cured and consequently, compressive strength of the DCM treated soils increases and satisfies the design parameter. From this study it can be concluded that the cross-hole sonic logging can be used for the integrity test as well as monitoring the curing stage of the structures, successfully.

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The Effects of Prolonged Sitting in a Cross-legged Posture on Pulmonary Function in Young Adults

  • Son, Sung-Min
    • The Journal of Korean Physical Therapy
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    • v.34 no.1
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    • pp.1-5
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    • 2022
  • Purpose: The impact of prolonged sitting in a cross-legged posture on physiological factors has not been extensively studied. We therefore attempted to evaluate whether prolonged sitting in a cross-legged posture affects pulmonary function in normal young adults. Methods: Twenty-four participants were recruited in this study, and the participants were equally allocated to the normal sitting posture group (NSP group, n=12) or sitting posture with the cross-legs group (SPCL group, n=12). The NSP group sat on chairs without crossing their legs for 30 minutes, and the SPCL group sat on the chair with legs crossed (the right knee on the left knee or the left knee on the right knee) for 30 minutes. The pulmonary function of the subjects was evaluated based on forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FVC/FEV1, and peak expiratory flow (PEF) measured using a spirometer. Results: In the intra-group comparison, the SPCL group showed significant differences in FVC and FEV1 before and after sitting (p<0.05), but no significant differences (p>0.05) were observed in the NSP group. However, there were no significant differences between the two groups in the pulmonary function parameters measured before and after sitting (p>0.05). Conclusion: Our results confirmed that prolonged sitting in a cross-legged posture could have a negative influence on pulmonary function. Therefore, if a sitting position is maintained for a long time, the correct sitting posture should be maintained to prevent musculoskeletal disorders as well as to maintain normal pulmonary function.

Development of Manufacturing Technology for Center Floor Cross Member with Roll Forming Process (롤 포밍 공법을 이용한 고강도 차체 부품 제작 기술 개발)

  • Kim, D.K.;Park, S.E.;Cho, K.R.;Lee, K.H.;Kim, K.H.;Lee, M.Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.10a
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    • pp.297-300
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    • 2009
  • The roll forming process is often used to manufacture long, thin-walled products such as a pipe. The final cross-section is a comparatively simple open-channel, a closed tube section or a complex profile with several bends. In recent years, that process is often applied to the bumper beam in the automotive industries. In this study, a optimal Center Floor Cross Member manufacturing technology, model deign and proper roll-pass sequences can be suggested by forming number of roll-pass and bending angle, and also effects of the process parameters on the final shape formed by roll forming defects were evaluated.

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The buckling of a cross-ply laminated non-homogeneous orthotropic composite cylindrical thin shell under time dependent external pressure

  • Sofiyev, A.H.
    • Structural Engineering and Mechanics
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    • v.14 no.6
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    • pp.661-677
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    • 2002
  • The subject of this investigation is to study the buckling of cross-ply laminated orthotropic cylindrical thin shells with variable elasticity moduli and densities in the thickness direction, under external pressure, which is a power function of time. The dynamic stability and compatibility equations are obtained first. These equations are subsequently reduced to a system of time dependent differential equations with variable coefficients by using Galerkin's method. Finally, the critical dynamic and static loads, the corresponding wave numbers, the dynamic factors, critical time and critical impulse are found analytically by applying a modified form of the Ritz type variational method. The dynamic behavior of cross-ply laminated cylindrical shells is investigated with: a) lamina that present variations in the elasticity moduli and densities, b) different numbers and ordering of layers, and c) external pressures which vary with different powers of time. It is concluded that all these factors contribute to appreciable effects on the critical parameters of the problem in question.