• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1439-1449
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• 2007

The challenging aspect of CWR (continuous welded rail) is the additional axial forces in rails, mainly due to the thermal expansion of steel plate girder and rail itself. It has been found that these axial forces are proportional to girder length, total bridge length and bolt tightening forces. Also these forces are dependent to girder support conditions, types of bearings and their arrangements. With CWR, the authors' previous studies show that performance improvements like noise reduce, fatigue resistances and bearing durability increment can be expected. In addition to these effects, secondary effects due to the semi integral behavior between rail and bridge girder also can be expected. Special bearings which can reduce the absolute maximum axial forces have been developed, and applied to real 100m span bridge. The performance improvements were verified through site measurements and numerical analysis. The purpose of this study is to confirm the expected performance improvement aspects of steel plate girder bridges with CWR. To verify these aspects, girder stiffness changes, rail axial force changes, girder displacements and noise level were thoroughly measured and compared.

• Advances in aircraft and spacecraft science
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• 제7권6호
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• pp.517-536
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• 2020

The present study investigates axial vibration of a FG nanobeam using nonlocal elasticity theory under clamped-clamped and clamped-free boundary conditions. Power law, exponential law and sigmoid law are applied as grading laws to examine the effect of the material distribution on axial vibration of the FG nanobeam. A parametric study was done to examine the effect of length scale on the dynamic behavior of the structure and the results are presented. It was observed that consideration of the nonlocal length scale is essential when analyzing the free vibration of a FG nanobeam. The results of the present study can be used as benchmarks in future studies of FG nanostructures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.238-240
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• 1998

This paper deals with the design of a disk-type motor excited by permanent magnets. The main flux is oriented in the axial direction, yielding a pan cake type arrangement. the outer diameter is about 65mm, inner diameter is about 30mm, the axial length about 15mm. For reduce axial length and high efficiency, motor winding have been etched copper plate. After the introduction, the motor design is explained and characteristic of axial flux permanent magnet motor have been investigated. A prototype AFPM motor have been assembled and driving power supply are made. A characteristic of magnetical and electrical and characteristic are investigated.

• Computers and Concrete
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• 제31권1호
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• pp.1-7
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• 2023

In this paper, Timoshenko-beam model is developed for the vibration of double carbon nanotubes. The resulting frequencies are gained for axial wave mode and length-to-diameter ratios. The natural frequency becomes more prominent for lower length-to-diameter ratios and diminished for higher ratios. The converse behavior is observed for axial wave mode with clamped-clamped and clamped-free boundary conditions. The frequencies of clamped-free are lower than that of clamped-clamped boundary condition. The eigen solution is obtained to extract the frequencies of double walled carbon nanotubes using Galerkin's method through axial deformation function. Computer softer MATLAB is used for formation of frequency values. The frequency data is compared with available literature and found to be in agreement.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1050-1055
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• 2008

The demand on a turnout layed on a bridge is rising owing to the increasing number of stations on the viaduct. And also the demand on a turnout with CWR is rising to upgrade running speed of the passing train. A CWR with turnout is subjected to additional axial force induced by the thermal expansion of bridge as well as lead rail of turnout. The additional axial force is closely related with the distance between bridge expansion joint and turnout when it is located near the movable bearing of bridge, and it is required to keep some distance to prevent excessive axial stress in CWR. But, there is no guideline in specification for the proper distance from E.J. to turnout, and it caused problem in planning turnout or bridge. So, it this study, the parametric study to investigate the effect on axial stress in CWR with turnout according to span length and distance between bridge expansion joint and turnout was performed. From the results of numerical analysis, it was found out that $5{\sim}30m$ distance is required to prevent excessive axial in CWR for span length less 90m.

• Steel and Composite Structures
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• 제18권6호
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• pp.1569-1582
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• 2015

This study explores the lateral deflections of diagonal braces in concentrically-braced earthquake-resisting frames. The performance of this widely-used system is often compromised by the flexural buckling of slender braces in compression. In addition to reducing the compressive resistance, buckling may also cause these members to undergo sizeable lateral deflections which could damage surrounding structural components. Different approaches have been used in the past to predict the mid-length lateral deflections of cyclically loaded steel braces based on their theoretical deformed geometry or by using experimental data. Expressions have been proposed relating the mid-length lateral deflection to the axial displacement ductility of the member. Recent experiments were conducted on hollow and concrete-filled circular hollow section (CHS) braces of different lengths under cyclic loading. Very slender, concrete-filled tubular braces exhibited a highly ductile response, undergoing large axial displacements prior to failure. The presence of concrete infill did not influence the magnitude of lateral deflection in relation to the axial displacement, but did increase the number of cycles endured and the maximum axial displacement achieved. The corresponding lateral deflections exceeded the deflections observed in the majority of the previous experiments that were considered. Consequently, predictive expressions from previous research did not accurately predict the mid-height lateral deflections of these CHS members. Mid-length lateral deflections were found to be influenced by the member non-dimensional slenderness (${\bar{\lambda}}$) and hence a new expression was proposed for the lateral deflection in terms of member slenderness and axial displacement ductility.

• 대한기계학회논문집A
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• 제30권10호
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• pp.1255-1260
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• 2006

To maintain the structural integrity of steam generator tubes, 40% of wall thickness plugging criterion has been developed. The approach is for the steam generator tube with single crack, so that the interaction effect of multiple cracks can not be considered. Although, recently, several approaches have been proposed to assess the integrity of steam generator tube with two identical cracks whilst actual multiple cracks reveal more complex shape. In this paper, the coalescence pressure of steam generator tube containing multiple cracks of different length is evaluated based on the detailed 3-dimensional (3-D) elastic-plastic finite element (FE) analyses. In terms of the crack shape, two collinear axial through-wall cracks with different length were considered. Furthermore, the resulting FE coalescence pressures are compared with FE coalescence pressures and experimental results for two identical collinear axial through-wall cracks to quantify the effect of crack length ratio on failure behavior of steam generator tube with multiple cracks. Finally, based on 3-D FE results, the coalescence evaluation diagrams were proposed.

• 한국안광학회지
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• 제15권3호
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• pp.201-206
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• 2010

목적: 본 연구는 유치원생들을 대상으로 안광학 성분 값들과 굴절이상도 간의 상관성을 알아보고자 하였다. 방법: 대상자는 안질환이 없는 유치원생 80안으로 하였다. 굴절검사, 각막굴절력, 각막곡률반경, 안축장, 전방깊이를 검사하고 분석 하였다. 안축장과 각막 굴절력사이에서 가장 높은 상관성을 보였다(r=-0.674, p=0.000). 키, 몸무게, 안축장(AL)/각막곡률반경(CR)비가 안축장과 양의 상관성을 보였다(r=0.351, r=0.408, r=0.488). 굴절이상과 각막굴절력은 안축장과 음의 상관성을 보였다(r=-0.302, r=-0.674). 전방깊이, 각막굴절력은 AL/CR 비와 양의 상관성을 보였다(r=0.422, r=0.280). 굴절이상, 각막곡률반경은 AL/CR 비와 음의 상관성을 보였다(r=-0.448, r=-0.396). 결론: 취학 전 어린들에 있어서 눈의 굴절이상을 진단하는데 AL/CR 비가 매우 중요한 지표임을 알 수 있었다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제26회 춘계학술대회논문집
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• pp.297-305
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• 2006

본 논문에서는 터빈의 형상 변수에 따른 부분흡입형 초음속 터빈 손실 특성을 분석하기 위하여 초음속 노즐 형상, 축방향 간극 길이, 로터 앞전의 모서리각에 따른 초음속 터빈내 유동 해석을 실시하였다. 먼저 축방향 간극을 진행하면서 발생하는 유동의 익렬 팁방향의 휘어짐은 초음속 노즐 형상에 크게 영향을 받는다. 다음으로 모서리각은 익렬 앞전에서 발생하는 충격파등의 강도를 결정한다. 마지막으로 축방향 간극에서 발생하는 유동의 확산 및 혼합은 축방향 간극 길이에 크게 영향을 받았다. 따라서 터빈내에서 발생하는 손실 중 유체역학적 손실은 노즐 형상과 로터 앞전의 모서리각에 의해 결정되었으며, 부분 흡입 손실은 노즐 형상 및 축방향 간극 길이에 영향을 받았다.

• Communications for Statistical Applications and Methods
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• 제15권5호
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• pp.775-781
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• 2008

It is developed that a family of the semicircular Laplace distributions for modeling semicircular data by simple projection method. Mathematically it is simple to simulate observations from a semicircular Laplace distribution. We extend it to the l-axial Laplace distribution by a simple transformation for modeling any arc of arbitrary length. Similarly we develop the l-axial log-Laplace distribution based on the log-Laplace distribution. A bivariate version of l-axial Laplace distribution is also developed.