• 한국철도학회논문집
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• 제17권5호
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• pp.355-364
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• 2014

연속철근 콘크리트궤도에서는 온도 및 수분 변화에 따른 구속응력에 의해 횡균열이 발생한다. 이러한 균열은 연속철근 콘크리트궤도의 거동과 장기 공용성에 상당한 영향을 미치는 것으로 알려져 있다. 이와 같은 횡균열이 콘크리트궤도의 거동에 미치는 영향을 분석하고 균열 관리 기준을 보다 합리적으로 결정하기 위해, 이 연구에서는 연속철근 콘크리트궤도에 열차하중이 작용할 때 균열이 발생한 궤도 슬래브(TCL)와 기층(HSB)의 응력 분포를 3차원 유한요소해석 모델을 이용하여 예측하였다. 해석 결과에 따르면 균열 깊이가 증가할 경우 TCL의 휨응력과 TCL-HSB 경계부 수직응력이 증가하고, 균열이 슬래브를 관통할 경우 TCL 균열부에서 철근 주변에 국부적으로 수직 응력이 커져 장기적으로 펀치아웃 발생 가능성이 커질 수 있다. 반면 균열폭과 간격의 영향은 균열 깊이에 비해 크지 않은 것으로 나타났다. 따라서 균열폭과 간격만 관리하는 것보다는 균열 깊이를 동시에 관리할 필요가 있다. 또한 HSB 수축 줄눈의 위치를 침목 사이에 위치하도록 하는 것이 장기 공용성 확보에 더 유리하다.

• 한국도로학회논문집
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• 제7권4호
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• pp.125-140
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• 2005

본 연구에서는 콘크리트 포장에서 발생하는 소음을 저감시키기 위한 최적의 임의간격 횡방향 타이닝 설계 간격을 제안하였다. 기존 문헌조사를 바탕으로 소음 발생에 대한 원인을 규명하였고, LCG(linear congruential generators) 알고리즘 이론을 이용하여 특정 주파수에 집중되는 에너지를 효과적으로 분산시킬 수 있는 타이닝의 간격을 설계하였다. 실내 시뮬레이션 결과를 대구-포항 고속국도 현장에 적용하였고 기존 국내외에 적용된 임의간격 횡방향 타이닝 시공도 병행하여 실내 외 소음 및 교통소음을 비교하였다. 실내 외 소음 측정 결과, 피치 소음으로 인한 소음을 감소시킴으로써 임의간격 횡방향 타이닝 구간이 일반구간 보다 낮은 소음도를 보였으나, 그 효과가 크지 않았다. 교통 소음 측정에서도 전체적으로 일반 타이닝 구간에 비해 임의 간격 횡방향 타이닝 구간에서 더 큰 소음저감 효과를 확인할 수 있었으나, pass-by 소음 측정과는 다소 차이를 보였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(II)
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• pp.522-530
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• 2003

Generally, diaphragms are installed in the box girder to prevent or decrease the distortion of the cross section. In engineering practice, diaphragms are spaced in 5m intervals without reasonable basis. the usual diaphragm type is solid-plate type. It is considered to be noneconomical design to the almost design engineers. In this paper, the parametric study was performed to present the design proposal about the diaphragm stiffness and spacing only in the single cell box girder. For that, the distortional warping normal stress, bending normal stress and transverse bending normal stress were analyzed using finite element program 'SMB' for the accurate structural analysis.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.62-65
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• 2006

This study investigated the behavior of R/C column confined with headed crossties subjected to eccentric loading. The 16 specimens are designed to have adequate confinement steel, determined by ACI seismic design. The variables studied in this research test are eccentricity to depth ratios, spacing of lateral steel and the anchor type of end of crossties. From the test results, all columns showed similar behavior up to the peak load but those columns laterally confined with head presented more ductile behavior after the peak load. The comparisons indicate that the flexural behavior of confined-concrete columns can be computed resonable accurately by P-M interaction curve.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.402-405
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• 2006

Inner support regions of continuous steel and concrete composite bridge decks, transverse crackings are easely developed by tensile forces due to live loads and primary and secondary effects of concrete shrinkage. Since these cracks have an influence on the durability of bridge decks, crack width should be controlled within allowable limit values. Although crack width is a function of steel stress, bar diameter, bar spacing, etc, the current code for the amount of longitudinal reinforcements provides only one value of 2 percent of the concrete area. In order to investigate cracking bahaviors of composite girders with the variation of the longitudinal steel ratios, negative flexural tests are conducted on five composite girders and crack width and crack spacing are compared to ACI Code and Eurocode. Based on the test results, it is discussed the suitability of the current code for the longitudinal steel ratio.

• Coupled systems mechanics
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• 제9권1호
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• pp.29-46
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• 2020

In this paper we deal with stability problems of any complex structure that can be modeled by beam and shell finite elements. We use for illustration the steel plate girders, which are used in bridge construction, and in industrial halls or building construction. Long spans, slender cross sections exposed to heavy loads, are all critical design points engineers must take into account. Knowing the critical load that will cause lateral torsional buckling of the girder, or load that can lead to web buckling, as an important scenario to consider in a design process.Many of such problem, including lateral torsional buckling with influence of lateral supports and their spacing on critical load can be solved by the proposed method. An illustrative study of web buckling also includes effects of position and spacing of transverse and longitudinal web stiffeners, where stiffeners can be modelled optionally using shell or frame elements.

• 한국자동차공학회논문집
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• 제9권2호
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• pp.99-106
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• 2001

NHTSA has been conducting biomechanical studies to reduce inujuries sustained sustained during automotive collision. Furthermore, NHTSA added the regulation to the FMVSS 201, limiting the equivalent HIC(Head Injury Criterion) value under 1000. In the presont work, a methodology was developed for the optimum design of the A-pillar trim with rib-structures. The design variables for the rib-strucrures were the transverse spacing, the longitudinal spacing, and the thickness. The required sets of the design varibles were decided based on the design of experiments. The head impact simulations were carried out using the LS-DYNA3D, and the HIC(d) values were computed using the resulrs of the head impact simulation. The objective function was constructed using the response surface methed (RSM). When the obtained optimum values were not inside the region of interest, the design proceduers were repeated by changing the region of interest. Finally, an A-pillar trim with rib-structures, which resulred in HIC(d) value under 850 for 15 mph head-trim impact, was developed.

• 대한기계학회논문집B
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• 제29권1호
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• pp.16-26
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• 2005

Air-cooled heat sinks are employed in many electronic cooling applications since they provide significant heat transfer enhancement and operational flexibility. Strip-shaped fin heat sink is of interest and needs to be investigated as general cooling products for more applicability. The purposes of this study are to evaluate heat sink performance without bypass flow condition and to determine optimal heat sink geometries. The results show that the decreasing rate of thermal resistance of a heat sink decreases with increasing inlet air velocity, and the increasing rate of pressure drop increases with increasing inlet air velocity, but is not affected by input power. The increasing rate of optimal longitudinal fin spacing is larger than that of transverse fin spacing. The strip fin heat sink tested in this study showed better cooling performance compared to that of other plate fin type.matism. 2004; 50(11): 3504-3515.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.133-144
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• 2003

Generally, diaphragms are installed in the box girder to prevent or decrease the distortion of tile cross section. In engineering practice, diaphragms are spaced in 5m intervals without reasonable basis. ANd the usual diaphragm type is solid-plate type. It is considered to be noneconomical design to the almost design engineers. In this paper, the parametric study was performed to present the design proposal about the diaphragm stiffness and spacing only in tire single cell box girder. For that, the distortional warping normal stress, bending normal stress and transverse bending normal stress were analyzed using finite element program 'SMB' for the accurate structural analysis.

• Journal of Advanced Marine Engineering and Technology
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• 제25권4호
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• pp.857-868
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• 2001

The aerodynamic forces and wake structures of the non-rotating downstream cylinder which is located behind the spinning upstream cylinder in tandem and staggered arrangement have been investigated by experimental method at Re= $1.32{\times}10^4$. The measurements of wake flow and pressure distributions of downstream cylinder are carried out in various spin parameters by combination of both longitudinal spacing rations L/d=1.5, 3.0, 4.5 and transverse spacing ratios T/d =0.0, -0.5, 0.5. For the present experiment, it has been found that the spin parameter of spinning upstream cylinder affect more easily the downstream cylinder in tandem arrangement than that in staggered arrangement.