• 한국강구조학회 논문집
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• 제23권3호
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• pp.327-335
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• 2011

본 연구의 목적은 강구조 비가새 골조의 열화특성에 영향을 미치는 구조적 인자들을 해석적인 방법으로 평가하고 설계 초기 단계에서 열화 현상을 근사적으로 평가할 수 있는 방안을 제안하는데 있다. 해석적 연구를 위해 arc length method를 적용한 2차원 2차 수정 소성힌지 해석법을 적용하였으며, 단층 단스팬 골조와 다층 단스팬, 다층 다스팬 골조에 대해 해석을 수행하였다. 해석의 주요 변수로는 축력비와 기둥 보의 강성변화를 적용하였다. 연구 결과 무차원 열화강성은 부재의 강성과 축력비에 모두 영향을 받는 것으로 나타났으나, 축력비가 열화강성에 주는 영향이 더욱 큰 것으로 나타났다. 이를 바탕으로 축력비를 변수로 한 열화 강성 평가식을 제안하였다.

• 대한기계학회논문집B
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• 제27권10호
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• pp.1450-1456
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• 2003

Three-dimensional pipe flows with elbows, tees and headers in three different pipe systems are calculated to estimate the effect of asymmetry of axial velocity profile and swirl on measuring accuracy of an orifice flowmeter. It is evaluated how the pressure difference across the orifice is dependent on the upstream straight pipe length and how swirl intensity, swirl angle, and axial velocity distribution affect the measuring error of the orifice flowmeter. From the results, it is found that variation of the pressure difference across the orifice is negligible in case that maximum swirl angle is less than 2$^{\circ}$, and also that the pressure difference across the orifice is more sensitive to the asymmetry of axial velocity profile rather than the swirl intensity.

• 대한기계학회논문집A
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• 제25권1호
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• pp.127-134
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• 2001

Wire ropes are widely used in cable car, suspension bridge and elevator, etc. and composed of single or multi-layer strands. It is difficult to find out the characteristics of a strand or wire rope because of complicated geometry and contact condition. In this study, the axial stiffness is evaluated using finite element method and reliable finite element analysis model is presented, taking into consideration the convergence on the length. The axial stiffness predictive equation of a strand is developed using analysis of variance, which can be applicable for characterizing the relationship between load and displacement when the strand configuration is determined.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.168-171
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• 1999

For the axial crushing tests of various shape of tubes, it was reported that composite tubes need trigger mechanism to avoid brittle failure. In this study, static axial crush tests were performed with the new aluminum/GFRP hybrid tubes. Glass/Epoxy prepregs were wrapped around aluminum tube and co-cured. The failure of hybrid tube was stable and progressive without trigger mechanism, and specific energy absorption was increased to maximum 34% in comparison with aluminum tube. Effective energy absorption is possible for inner aluminum tube because wrapped composite tube constrain the deflection of aluminum tube and reduce the folding length. The failure of hybrid composite tube was stable without trigger mechanism because inner aluminum tube could play the role of crack initiator and controller. Aluminum/Glass-Epoxy hybrid tube is suitable for the vehicle front structure due to effective energy absorption capability, easy production, and simple application for RTM process.

• 설비공학논문집
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• 제7권1호
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• pp.142-149
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• 1995

Axial fans are very useful cooling devices being widely used in many electric and industrial machinery. However those are often accompanying annoying noise. Many efforts have been devoted in order to reduce the fan noise. In this study, the procedure was devided into two major parts in considering effects of design parameters of axial fan concerned with noise ; the fan theory and the Fukano's fan noise study. By using the fan theory we defined stagger angle, camber angle, blade inlet and outlet angle for studying low noise fan. Then the effects of such angles on the flow rate and static pressure were investigated. By using the Fukano's fan noise theory, the relations of the chord length, the rotational speed and the number of blades vs. fan noise are investigated.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.356-363
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• 2003

The CWR of the plate girder bridges in non-ballast causes the additional axial force on the rail and the bearing due to the temperature axial force and the interaction between the CWR and bridges. This study shows the remarkable improvement of reducing the axial force of the CWR on the non-ballast bridge, compared to conventional methods. New method, which is differently designed in terms of longitudinal semi-rigid bearing, reduces the axial force on the bearing by making the girder act both directions. This method is applicable to most cases of bridges regardless of the restriction of length, and useful to reduce the abrasion and damage of the track material.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권3호
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• pp.295-299
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• 2013

This paper presents the new structure of a spindle motor for hard disk drive (HDD). It can produce axial force as well as torque without a pulling plate or a pulling magnet required for the normal operation of a hydrodynamic bearing in rotating-shaft structure. The proposed models have different air gap length along the axial direction by changing the thickness of permanent magnet (PM). One has a single slope and the other has double slopes on the surface of PM. For the design of the proposed models, variables are defined and its effects on the motor performances are investigated by 3-demensional finite element analysis (FEA). The equi-performance curves are investigated for the main characteristics of the spindle motor such as generated torque, axial force and torque ripple ratio. The validity of the proposed models is verified by the feasibility study and performance evaluation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1043-1049
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• 2008

Trouble by excessive axial stress in CWR layed on a bridge is frequently happen, and this problem is induced from lack of considering on the track/structure interface on preliminary design stage. In this study, the sensitivity evaluation for the major influencing parameters, that is, expansion length of span, stiffness of super structure, arrangement of bearing, and strength of sub-structure, to the axial force in CWR on a bridge is conducted. From the sensitivity study, the guideline to reduce axial force efficiently in CWR for bridge engineer was suggested. The suggested guideline may not applicable for every case, but it is helpful for preliminary design of bridge.

• Steel and Composite Structures
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• 제30권1호
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• pp.69-79
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• 2019

Numerous problems have always vexed engineers with buckling, corrosion, bending, and over-loading in damaged steel structures. The present study aims to study the possible effects of Carbon Fiber Reinforced Polymer (CFRP) for strengthening deficient Steel Square Hollow Section (SHS) columns. To this end, the effects of axial loading, stiffness values, axial displacement, the shape of deficient on the length of steel SHS columns were evaluated based on a detailed parametric study. Ten specimens were tested to failure under axial compression in laboratory and simulated by using Finite Element (FE) analysis based on numerical approach. The results indicated that the application of CFRP sheets resulted in reducing stress in the damage location and preventing or retarding local deformation around the deficiency location appropriately. In addition, the retrofitting method could increase loading the carrying capacity of specimens.

• 지질공학
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• 제17권1호
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• pp.65-73
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• 2007

지하발전소 시공을 위한 지하대규모 공동 굴착시 소성영역이 크게 발생되므로 일반적으로 장대록볼트를 이용한다. 그러나 장대록볼트 설치시 록볼트 길이에 따른 휨발생과 정착효과에 대한 문제가 야기되고 있다. 따라서 본 연구는 지하대규모 공동 굴착시 가장 효율적인 정착방식을 결정하기 위하여 천단부와 측벽부에서 장대록볼트의 길이를 5.0m, 7.5m, 10.0m, 15.0m와 정착방식을 톱니 모양, 홈 모양 및 매끈한 모양으로 변경시키면서 현장인발시험을 실시하였다. 현장인발시험에 의하여 하중과 변위를 단계별로 측정하고 거동특성을 평가하여 개선된 정착방식을 제시하였다.