• 한국초전도ㆍ저온공학회논문지
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• 제2권1호
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• pp.24-30
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• 2000

This paper present the characteristics of the internal induced voltage and arc phenomena in liquid helium at the energy transfer from a superconducting magnet to a load resistor. Especially generation mechanism of the oscillated wave from of the coil terminal voltage is analyzed by considering circuit constant of the superconducting magnet, load condition and arc resistance of the mechanical opening switch. The wavefront and peak portion of the voltage are strongly influenced by arc discharge triggered by the switch separation in liquid helium. Abrupt arc extinction leads to voltage oscillation with an enormous peak. It is suggested that the superconducting magnet should be designed to ensure the internal surge when arc is possibly formed by switch opening or coil short circuit between turns or layers. Finally, a suppression method of the oscillating surge is proposed based on the load condition.

• 한국초전도ㆍ저온공학회논문지
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• 제4권2호
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• pp.63-67
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• 2002

In this study, the performance of the Stirling type orifice Pulse tube refrigerator (OPTR) with a linear compressor was investigated by experiment. The dynamic pressures at three points and a temperature at the cold heat exchanger are measured to explore the dependency of the orifice on the performance of the OPTR. The experimental results show that the opening of the orifice has significant effects on the no load temperature and cool down characteristics. The Pressure amplitude in Pulse tube decrease as the opening of the orifice increase, but the mass flow rate through the orifice and the electric input Power to the compressor increase. The results show that the operating frequency and charging Pressure does not affect on the no load temperature. The pressure amplitude in pulse tube decrease as the operating frequency increase or the charging Pressure decreased.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(II)
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• pp.1059-1064
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• 2002

The behavior of an opening and the performance of support system depend upon the load-deformation characteristics of ground and support as well as of the manner and of timing of support installation. The load-deformation characteristics of ground and support are derived by the interaction between ground and support. The interaction between ground and support is qualitatively illustrated by a ground response curve. The behavior of an opening and the performance of support system depend upon the load-deformation characteristics of ground and support as well as of the manner and of timing of support installation. The interaction between ground and support is qualitatively illustrated by a ground response curve. The convergence-confinement method don't need the basic assumptions for a mathematical model. Also This is applicable to general tunnel. Consequently the stability of tunnel must be qualitatively investigated by a ground response curve and quantitatively adjudged by a numerical analysis for the reasonable design of tunnel.

• Steel and Composite Structures
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• 제18권3호
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• pp.641-657
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• 2015

Application of reduced web beam section (RWBS) as a sacrificial fuse element has become a popular research field in recent years. Weakening of beam web in these connections may cause local web buckling around the opening area which can affect cyclic behavior of connection including: maximum load carrying capacity, strength degradation rate, dissipated energy, rotation capacity, etc. In this research, effect of local web buckling on the cyclic behavior of RWBS connections is investigated using finite element modeling (FEM). For this purpose, a T-shaped moment connection which has been tested under cyclic loading by another author is used as the reference model. Fracture initiation in models is simulated using Cyclic Void Growth Model (CVGM) which is based on micro-void growth and coalescence. Included in the results are: effect of opening corner radii, opening dimensions, beam web thickness and opening reinforcement. Based on the results, local web buckling around the opening area plays a significant role on the cyclic behavior of connection and hence any parameter affecting the local web buckling will affect entire connection behavior.

• 전기학회논문지
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• 제60권4호
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• pp.759-765
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• 2011

This paper proposes an effective assistant model for considering the stator slot-opening effect on air gap flux density distribution in conventional interior-type permanent magnet (IPM) motor. Different from the conventional slot-opening effect analysis in surface-type PM (SPM) motor, a composite effect of slot-opening uniquely existing in IPM motor, which additionally causes enhancement of air gap flux density due to magnet flux path distortion in iron core between the buried PM and rotor surface. This phenomenon is represented by a proposed assistant model, which simply deals with this additional effect by modifying magnetic pole-arc using an effective method. The validity of this proposed analytical model is applied to predict the air gap flux density distribution in an IPM motor model and confirmed by finite element method (FEM).

• 대한기계학회논문집
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• 제14권1호
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• pp.96-102
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• 1990

본 연구에서는 압력용기 소재인 SPV 50Q와 고압강관 소재로 사용하는 SPV 50Q 와 고압강간 소재로 사용하는 API 5A-K55에서의 표면균열의 표면방향과 깊이방향 또한 두께 평균에 대한 균열열림을 스트레인 게이지와 CMOD(Crack Mouth Opening Displace- ment)게이지를 이용하여 측정 비교하였다. 또한 표면균열의 균열 열림하중을 측정위 치에 따라 평가하고, 본연구에 사용한 두 소재에 대해 균열 열림을 고려한 표면균열 진전평가가 각 방향에 대해 이루어졌다.

• 대한기계학회논문집B
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• 제39권8호
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• pp.703-711
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• 2015

작업의 효율을 높이기 위해서 대형 공장에서 개구부는 주로 개방 되어 있다. 그러나 동절기에 공장에서 난방을 하는 경우 개방되어 있는 개구부는 난방부하를 상승시키는 큰 요인이다. 때문에 공장에서는 개구부 상단에 에어커튼을 설치하여 외부의 침기를 막아 난방부하를 낮춘다. 일반적인 에어커튼의 설계 변수로는 토출 각도와, 속도, 온도 등이 존재하며 이에 대한 연구는 이미 많이 진행되었다. 하지만, 공장이라는 공간적 특수성을 고려하였을 때, 기존에 연구되지 않은 개구부로부터의 이격 거리와 토출구 폭에 대한 부분도 차단 성능에 영향을 미친다. 그 결과 에어커튼은 이격 거리가 가깝고, 토출구 폭은 넓을수록 차단 성능이 좋았다. 이격 거리가 존재하더라도 토출구 폭을 증가시키면 차단 성능이 향상되었으며, 토출구 폭을 증가시킴으로써 약 13.7%의 차단 성능의 향상을 기대할 수 있다.

• Structural Engineering and Mechanics
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• 제72권3호
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• pp.383-393
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• 2019

Horizontal openings in reinforced concrete (RC) beams are quite often used to accommodate service pipelines. Several research papers are available in the literature describing their effect. RC beams with vertical openings are commonly used to accommodate service lines in residential buildings in Kuwait. However, there are lack of design guidelines and best practices reported in the literature for RC beams with vertical openings, whereas the detailed guidelines are available for beams with horizontal openings. In the present paper, laboratory experiments are conducted on nine RC beams with and without vertical openings. Parametric study has been carried out using nonlinear finite element analysis (FEA) with changes in the diameter of the opening, various positions of the opening along the length and width of the beam, edge distance, etc. 50 finite element simulations were conducted. The FEA results are verified using the results from the laboratory experiments. The study showed that the load carrying capacity of the beam is reduced by 20% for the RC beam with vertical openings placed near the center of the beam compared to a solid beam without an opening. Significant reduction in load carrying capacity is observed for beams with an opening near the support (${\approx}15%$). The overall stiffness of the beam, crack pattern and failure modes were not affected due to the presence of the vertical opening. Furthermore, an artificial neural network (ANN) analysis is carried out using the FEA generated data. The results and observations from the ANN and FEA are in good agreement with experimental results.

• Computers and Concrete
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• 제33권3호
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• pp.251-264
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• 2024

The present study pertains to the effects of variations in the location and size of drilled web openings on the behavior of fixed-fixed reinforced concrete (RC) beams. For this purpose, a reference bending beam with a transverse opening in each half span was tested to failure. Later, the same beam was modeled and analyzed with the help of finite element software using ABAQUS. Upon achieving close agreement between the experimental and numerical results, the location and size of the web opening were altered to uncover the effects of these factors on the shear strength and load-deflection behavior of RC beams. The experimental failure mode of the tested beam and the numerical results were also verified by theoretical calculations. In numerical analysis, when compared to the reference (D0) specimen, if the distance of the opening center from the support is 0 or h or 2h, reduction in load-bearing capacity of 1.5%-22.8% or 2.0%-11.3% or is 4.1%-40.7%. In other words, both the numerical analyses and theoretical calculations indicated that the beam behavior shifted from shear-controlled to flexure-controlled as the openings approached the supports. Furthermore, the deformation capacities, energy absorption values, and the ductilities of the beams with different opening diameters also increased with the decreasing distance of the opening from supports. Web compression failure was shown to be the predominant mode of failure of beams with large diameters due to the lack of sufficient material in the diagonal compression strut of the beam. The present study indicated that transverse openings with diameters, not exceeding about 1/3 of the entire beam depth, do not cause the premature shear failure of RC beams. Finally, shear damage should be prevented by placing special reinforcements in the areas where such gaps are opened.

• 한국공작기계학회논문집
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• 제11권2호
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• pp.43-49
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• 2002

SB41 material is welded automatically and is investigated some effects of the welding residual stress in the growth and propagation of fatigue crack, so as to study the fatigue behaviour in the welding residual stress field. The summarized results are as follows; 1) In case of the load amplitude is constant, as the stress ratio is changing to 0.1, 0.33 and 0.5 the propagation life is constant but the growth life decreases. And than, when maximum load or minimum load is constant as the stress ratio increases the growth life and propagation life. 2) It was shown that fatigue crack propagation ratio da/dN was almost constant regardless of the stress ratio change at constant load amplitude and that the larger stress ratio, the slower was the fatigue crack propagation ratio. 3) The opening ratio U is influenced by $K_max$ but it isn't only the function of $K_max$ because data range is very large. 4) The fatigue life of the specimens on tensile compressive residual stress field was decreased and increased respectably more than that of the base metal.