• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 춘계학술발표논문집 1부
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• pp.132-134
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• 2010

In this paper new, inverter control system for TG feedback a formula Control was developed. The motor control system with TG feedback controller as an effect of load disturbance, it is very difficult to guarantee the robustness of control system. The function of the implementation are TG feedback type, and temperature scheme. The Inverter Control System approach is based on master-slave control concept. To show validity of the developed new inverter control system, severial experiments are illustrated.

• Structural Engineering and Mechanics
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• 제81권5호
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• pp.551-563
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• 2022

Bolted connector could be an alternative to replace the conventional welded headed stud in steel-ultra high performance concrete (UHPC) lightweight composite structures. In this paper, a novel demountable bolted shear connector, consisting of a high-strength bolt (HSB) and a specially-designed nut which is pre-embedded in a thin UHPC slab, is proposed, which may result in the quick installation and disassembly, due to the mountable, demountable and reusable features. In order to study the shear behavior of the new type of bolted shear connector, static push-out tests were conducted on five groups of the novel demountable bolted shear connector specimens and one group of conventional welded headed stud specimen for comparison. The effect of the bolt shank diameter and aspect ratio of bolt on failure mode, shear stiffness, peak slip at the steel-UHPC interface, shear strength and ductility of novel bolted connectors is investigated. Additionally, design formula for the shear strength is proposed to check the suitability for assessment of the novel demountable bolted shear connectors.

• Structural Engineering and Mechanics
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• 제91권4호
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• pp.403-416
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• 2024

The single-column pier girder bridge, due to its low engineering cost, small footprint, and aesthetic appearance, is extensively employed in urban viaducts and interchange ramps. However, its structural design makes it susceptible to eccentric loads, flexural-torsional coupling effects, and centrifugal forces, among others. To evaluate its anti-overturning performance reasonably, it is crucial to determine the reaction force of the support for the single-column pier girder bridge. However, due to the interaction between vehicle and bridge and the complexity of vibration modes, it poses a significant challenge to analyze the theory or finite element method of single-column pier girder bridges. The unit load bearing reaction coefficient method is proposed in this study to facilitate the static analysis. Numerous parameter analyses have been conducted to account for the dynamic amplification effect. The results of these analyses reveal that the dynamic amplification factor is independent of road surface roughness but is influenced by factors such as the position of the support. Based on parameter analysis, the formula of the dynamic amplification factor is derived by fitting.

• 대한토목학회논문집
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• 제26권1D호
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• pp.1-11
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• 2006

본 연구에서는 소음에 대한 이론적 연구와 도로교통소음에 관하여 살펴보았다. 그리고 국내의 도로소음예측모델을 다른 선진국의 모델과 비교 분석하여 예측인자의 적용현황 및 적용상의 문제점을 도출하였다. 일반식 정립을 위한 사례연구에서는 국립환경연구원에서 제안한 식에 적용한 예측치와 실측치를 비교하여 국내의 도로교통소음 예측모델의 개선점을 살펴보았다. 또한 소음에 대한 통행량과 속도의 관계를 고찰해보기 위해서, 이 식에서 주요 요인으로 사용한 통행량과 속도의 두 요인 중에서 무엇이 더 큰 영향을 가지는지를 회귀분석을 통하여 속도가 통행량보다 더 밀접한 관계가 있음을 알 수 있었다. 따라서 도로소음을 줄이기 위해서는 차량의 통행량의 고려도 중요하지만 차량의 속도 규제가 더욱 중요하다고 볼 수 있다. 지구보정치 도출을 위한 사례연구에서는 도로교통소음이 단지내에 공간적으로 미치는 영향을 분석하고자 하였다. 세 아파트 단지의 도로교통소음을 측정하여 비교 분석함으로써 도로교통소음은 단지내에 평면적 입체적으로 영향을 미치고 있음을 확인하였다. 즉, 소음원에서 거리가 멀어질수록 소음의 크기가 적어지고, 높은 위치로 올라갈수록 소음의 크기는 증가하다가 어느 정도 높이 이상에서는 다시 소음의 크기는 줄어들고, 소음의 방향에 장애물이 있을 경우 소음의 영향이 줄어들었다. 따라서 단지내에 소음이 미치는 영향을 이러한 점들을 고려하여 공간적으로 파악한 단지 설계를 해야 한다.

• 대한조선학회논문집
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• 제44권2호
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• pp.64-73
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• 2007

Turbulent flows around yacht sails were calculated to access the applicability of CFD for yacht design. Multi-block grid system was generated by using Gridgen package and Fluent was used to calculate flows around two sail system. A 30ft class sailing yacht designed and tested by KRISO was chosen. The interference effect between main and jib sails was analyzed. Pressure distribution on the sails was obtained and the center of effort was estimated. It was found that the jib angle affects the flow phenomena around a main sail due to the change of inflow angle. The location of center of effort is much different from the empirical formula based on a simple geometrical consideration. The calculated results are compared with the previous numerical and experimental results. Both CFD results are similar, but there are some discrepancies with experimental data. However, it is certain that CFD can be a very useful tool for yacht design.

• Structural Engineering and Mechanics
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• 제63권2호
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• pp.195-206
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• 2017

This paper presents the parametric numerical analysis on the ultimate bearing capacity of the purlin-sheet roofs connected by standing seam clips. The effects of several factors on failure modes and ultimate bearing capacity of the purlins are studied, including setup of anti-sag bar, purlin type, sheet thickness and connection type et al. A simplified design formula is proposed for predicting the ultimate bearing capacity of purlins. Results show that setting the anti-sag bars can improve the ultimate bearing capacity and change the failure modes of C purlins significantly. The failure modes and ultimate bearing capacity of C purlins are significantly different from those of Z purlins, in the purlin-sheet roof connected by standing seam clips. Setting the anti-sag bars near the lower flange is more favorable for increasing the ultimate bearing capacity of purlins. The ultimate bearing capacity of C purlins increases slightly with sheet thickness increasing from 0.6 mm to 0.8 mm. The ultimate bearing capacity of the purlin-sheet roofs connected by standing seam clips is always higher than those by self-drilling screws. The predictions of the proposed design formulas are relatively in good agreement with those of EN 1993-1-3: 2006, compared with GB 50018-2002.

• 한국농공학회지
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• 제38권3호
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• pp.58-69
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• 1996

In recent years, the research and development about the new material proceeds rapidly and actively. In building industry, high strength concrete is of interest as a new material. Since the building structure becomes bigger, higher and more specialized, the demand of material and member with high strength expands greatly. Therefore in this experiment, cement complex with high strength was made using the condensed silica fume, a basic experiment was performed on strength property, and optimum-mixture-state was determined for manufacturing a high-strength concrete. Shear behaviour and fracture property of concrete beams with high strength were evaluated. On the whole, in spite of many researches, it is one of the difficult problems that shear fracture of concrete beams has not yet been clearly understood theoretically, and now the shear-design-standard forms in many countries are a formula based on experiment. In this study, the variable of shear behavior experiment was shear-reinforcement-ratio. By analyzing test results and comparing with computation value by ACI code, the basic data was offered on shear design of reinforced concrete beams with high strength. The effect of epoxy repair was also investigated for the beams with cracks due to flexural and shear loading.

• Steel and Composite Structures
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• 제13권3호
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• pp.277-293
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• 2012

The interaction between steel tube and concrete core is the key design considerations for concrete-filled steel tube columns. In a concrete-filled steel tube (CFST) column, the steel tube provides confinement to the concrete core which permits the composite action among the steel tube and the concrete. Due to construction faults and plastic shrinkage of concrete, the debonding separation at the steel-concrete interface weakens the confinement effect, and hence affects the behaviour and bearing capacity of the composite member. This study investigates the axial loading behavior of the concrete filled circular steel tube columns with debonding separation. A three-dimensional nonlinear finite element model of CFST composite columns with introduced debonding gap was developed. The results from the finite element analysis captured successfully the experimental behaviours. The calibrated finite element models were then utilized to assess the influence of concrete strength, steel yield stress and the steel-concrete ratio on the debonding behaviour. The findings indicate a likely significant drop in the load carrying capacity with the increase of the size of the debonding gap. A design formula is proposed to reduce the load carrying capacity with the presence of debonding separation.

• Earthquakes and Structures
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• 제16권1호
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• pp.83-96
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• 2019

The seismic behavior of PRC coupling beam-hybrid coupled shear wall system is analyzed by using the finite element software ABAQUS. The stress distribution of steel plate, reinforcing bar in coupling beam, reinforcing bar in slab and concrete is investigated. Meanwhile, the plastic hinges developing law of this hybrid coupled shear wall system is also studied. Further, the effect of coupling ratio, section dimensions of coupling beam, aspect ratio of single shear wall, total height of structure and the role of slab on the seismic behavior of the new structural system. A fitting formula of plate characteristic values for PRC coupling beams based on different displacement requirements is proposed through the experimental date regression analysis of PRC coupling beams at home and abroad. The seismic behavior control method for PRC coupling beam-hybrid coupled shear wall system is proposed based on the continuous connection method and through controlling the coupling ratio, the roof displacement, story drift angle of hybrid coupled shear wall system, displacement ductility of coupling beam.

• Structural Engineering and Mechanics
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• 제47권5호
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• pp.643-660
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• 2013

In the present work, the capacity ratings of steel truss bridges have been carried out incorporating dynamic effect of moving vehicles and its accumulating effect as fatigue. Further, corrosion in the steel members has been taken into account to examine the rating factor. Dynamic effect has been considered in the rating procedure making use of impact factors obtained from simulation studies as well as from codal guidelines. A steel truss bridge has been considered to illustrate the approach. Two levels of capacity ratings- the upper load level capacity rating (called operating rating) and the lower load level capacity rating (called inventory rating) were found out using Load and Resistance Factor Design (LRFD) method and a proposal has been made which incorporates fatigue in the rating formula. Random nature of corrosion on the steel member has been taken into account in the rating by considering reduced member strength. Partial safety factor for each truss member has been obtained from the fatigue reliability index considering random variables on the fatigue parameters, traffic growth rate and accumulated number of stress cycle using appropriate probability density function. The bridge has been modeled using Finite Element software. Regressions of rating factor versus vehicle gross weight have been obtained. Results show that rating factor decreases when the impact factor other than those in the codal provisions are considered. The consideration of fatigue and member corrosion gives a lower value of rating factor compared to those when both the effects are ignored. In addition to this, the study reveals that rating factor decreases when the vehicle gross weight is increased.