• International Journal of Aeronautical and Space Sciences
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• 제18권4호
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• pp.651-661
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• 2017

A truss-braced wing (TBW) aircraft has recently received increasing attention due to higher aerodynamic efficiency compared to conventional cantilever wing aircraft. For conceptual TBW aircraft design, we developed a propulsion-and-airframe integrated design environment by replacing a semi-empirical turbofan engine model with a thermodynamic cycle-based one built upon the numerical propulsion system simulation (NPSS). The constructed NPSS model benefitted TBW aircraft design study, as it could handle engine installation effects influencing engine fuel efficiency. The NPSS model also contributed to broadening TBW aircraft design space, for it provided turbofan engine design variables involving a technology factor reflecting progress in propulsion technology. To effectively consolidate the NPSS propulsion model with the TBW airframe model, we devised a rapid, approximate substitute of the NPSS model by reduced-order modeling (ROM) to resolve difficulties in model integration. In addition, we formed an artificial neural network (ANN) that associates engine component attributes evaluated by object-oriented weight analysis of turbine engine (WATE++) with engine design variables to determine engine weight and size, both of which bring together the propulsion and airframe system models. Through propulsion-andairframe design space exploration, we optimized TBW aircraft design for fuel saving and revealed that a simple engine model neglecting engine installation effects may overestimate TBW aircraft performance.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1994년도 봄 학술발표회 논문집
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• pp.49-56
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• 1994

The purpose of this study is to construct a total design & manufacturing system for the Space-Truss structure. In this study, we choose the transmission tower as the study model to show the possibility of a Total System for another space truss structure. We are confident that this total system should provide more convenience, accuracy and should help to save time from the design stage to construct stage of the transmission tower.

• 한국산업융합학회 논문집
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• 제22권4호
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• pp.387-394
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• 2019

This paper presents an analytical study on the strength and stiffness of various types of truss structures. The applied models are triangular-like opened truss-wall triangular model (OTT), closed truss-wall triangular model (CTT), opened solid-wall triangular model (OST), and hypercube models defined as core-filled or core-spaced cube. The models are analyzed by numerical model analysis using DEFORM 2D/3D tool with AISI 304 stainless steel. Then, the ideal solutions for stiffness and strength are defined. Finally, the relative elastic modulus of the core-spaced model is obtained as 0.0009, which is correlated with the cancellous bone for the relative density range of 0.029-0.03, and the relative elastic modulus for the core-filled model is obtained as 0.0015, which is correlated with cancellous bone for the relative density range of 0.035-0.036. For the relative compressive yield strength, the OTT reasonably agrees with the cancellous bone for the relative density of 0.042 and the relative compressive strength of 0.05. The CTT and OST are in good agreement at the relative density of 0.013 and the relative compressive yield strength of 0.002. The hypercube models can be used for the cancellous bone for stiffness, and the triangular models can be used for the cancellous bone for strength. However, none of the models can be used to replace the compact bone because it requires much higher stiffness and strength. In the near future, compact bone replacement must be further studied. In addition, previously mentioned models should be developed further.

• 한국강구조학회 논문집
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• 제19권4호
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• pp.367-381
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• 2007

전력 수요의 증가로 인해 송전철탑의 고용량, 대용량화가 요구되어왔지만 아직 대부분을 차지하고 있는 345kV급 송전철탑에 대한 연구는 미흡한 실정이다. 현재 해석 설계되고 있는 방식은 2차원 트러스요소를 사용하여 양단은 힌지접합으로 축력만 작용하고 있는 것으로 가정한다. 이러한 방식을 3차원 트러스 요소에 적용하였을 때, 면 외로 작용하는 하중에 대해 무한변위가 발생하는 구조해석적인 문제점을 가지고 있다. 이에 본 연구는 보다 합리적인 요소 선택을 통한 구조해석 방식을 제안하기 위해 기존의 3차원 트러스요소 모델, 보요소 모델, 주주재와 수평재는 보요소로 모사하고 사재 및 기타 복재는 트러스로 모사한 보-트러스요소 모델 등 세 모델을 실제 설계 시공된 345kV급 송전철탑에 대해 설계하중 내에서 구조해석프로그램을 이용한 정적해석, 자유진동해석, 선형좌굴해석을 수행하였다. 구조해석 결과, 세 모델 모두 축력 및 축응력, 변위에서는 큰 차이가 나타나지 않았으나 보요소모델과 보-트러스요소 모델에서 휨응력의 비율이 축응력에 대해 크게 나타났다. 자유진동해석과 탄성좌굴해석의 결과를 통해 보-트러스요소 모델이 송전철탑 설계 및 해석에 있어서 더 안전측으로 고려될 수 있음을 확인하였다.

• 한국공간구조학회논문집
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• 제19권4호
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• pp.69-76
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• 2019

A stadium roof that uses the pin-jointed spatial truss system has to be designed by taking into account the unstable phenomenon due to the geometrical non-linearity of the long span. This phenomenon is mainly studied in the single-free-node model (SFN) or double-free-node model (DFN). Unlike the simple SFN model, the more complex DFN model has a higher order of characteristic equations, making analysis of the system's stability complicated. However, various symmetric conditions can allow limited analysis of these problems. Thus, this research looks at the stability of the DFN model which is assumed to be symmetric in shape, and its load and equilibrium state. Its governing system is expressed by nonlinear differential equations to show the double Duffing effect. To investigate the dynamic behavior and characteristics, we normalize the system of the model in terms of space and time. The equilibrium points of the system unloaded or symmetrically loaded are calculated exactly. Furthermore, the stability of these points via the roots of the characteristic equation of a Jacobian matrix are classified.

• 한국공간구조학회논문집
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• 제2권4호
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• pp.61-76
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• 2002

The structure system that is discreterized by continuous shells is usually used to make a large space structures and these structures show the collapse mechanisms that are captured at over the limit load, and snap-through and bifurcation are most well known of it. For the collapse mechanism, rise-span ratio, element stiffness and load mode are main factor, which it give an effect to unstable behavior. Moreover, resist force of structure can be reduced by initial condition and initial imperfection significantly. In order to investigate the instability of shell structures, the finite deformation theory can be applied and it becomes a nonlinear mathematics in which use equation of tangential stiffness incrementally. With an initial imperfection, using simple example and Flow Truss Dome, the buckling characteristics of space truss is main purpose of this paper, and unstable behavior is studied by proposed the numerical method. Also, by using MIDAS, this research work analyzes displacements and inner forces as the design load of model, and the ratio of buckling load of design load is investigated.

• 한국공간구조학회논문집
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• 제18권2호
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• pp.69-78
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• 2018

In current research, it was attempted a preliminary design and evaluation of non-uniform ultra high-strength concrete (UHSC) truss members. UHSC used here has the compressive strength of 180 MPa, the tensile strength of 8 to 20 MPa, and the tensile strain after cracks up to 2%. By the three-dimensional finite element stress analysis as well as strut-tie approach on concrete solid beams, the non-uniform truss shape of UHSC truss was designed with the architectural esthetic concept. In a series of examples, to compare with conventional concrete members, the proposed UHSC truss members have advantages in capabilities of the slender design with minimum weight with high performances under transverse loadings as well as the aesthetically non-uniform design for spatial structures.

• 한국구조물진단유지관리공학회 논문집
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• 제7권3호
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• pp.147-156
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• 2003

본 논문에서는 모드형상을 이용한 트러스 구조물의 손상탐지 방법을 소개하였다. 트러스 부재에 대한 손상탐지 이론은 손상 전과 손상 후의 모달 변형에너지의 차이점을 이용하여 정립하였으며, 이론의 타당성을 조사하기 위하여 1:6 축척의 6각형 트러스 구조물의 실험 데이터에 이론을 적용하였다. 손상 실험은 총 17가지의 시나리오로 구성되어 있으며, 손상 타입은 3가지로 구성되어있다. 17가지 실험 데이터에 대한 손상평가 결과, 본 연구에서 제안한 방법으로 트러스 부재의 손상을 성공적으로 탐지할 수 있었으며, 비교적 작은 손상의 경우 계측 데이터의 노이즈가 손상탐지 성능에 많은 영향을 미친다는 것을 확인하였다.

• Steel and Composite Structures
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• 제32권2호
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• pp.189-198
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• 2019

This paper aims to study the mechanical performance of three-tower four-span suspension bridges with steel truss girders, including the static and dynamic characteristics of the bridge system, and more importantly, the influence of structural parameters including the side-main span ratio, sag-to-span ratio and the girder stiffness on key mechanical indices. For this purpose, the Oujiang River North Estuary Bridge which is a three-tower four-span suspension bridge with two main spans of 800m under construction in China is taken as an example in this study. This will be the first three-tower suspension bridge with steel truss girders in the world. The mechanical performance study and parametric analysis are conducted based on a validated three-dimensional spatial truss finite element model established for the Oujiang River North Estuary Bridge using MIDAS Civil. It is found that a relatively small side-main span ratio seems to be quite appropriate from the perspective of mechanical performance. And decreasing the sag-to-span ratio is an effective way to reduce the horizontal force subjected to the midtower and improve the antiskid safety of the main cable, while the vertical stiffness of the bridge will be reduced. However, the girder stiffness is shown to be of minimal significance on the mechanical performance. The findings from this paper can be used for design of three-tower suspension bridges with steel truss girders.

• 국제강구조저널
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• 제18권4호
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• pp.1306-1317
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• 2018

For determining the in-plane buckling resistance of a concrete-filled steel tubular (CFST) arch, the current technical code GB50923-2013 specifies the use of an equivalent beam-column method which ignores the effect of rise-to-span ratio. This may induce a gap between the calculated result and actual stability capacity. In this study, a FE model is used to predict the buckling behavior of CFST truss arches subjected to uniformly distributed loads. The influence of rise-to-span ratio on the capacity of truss arches is investigated, and it is found that the stability capacity reduces as rise-to-span ratio declines. Besides, the calculations of equivalent slenderness ratio for different truss sections are made to consider the effect of shear deformation. Moreover, based on FE results, a new design equation is proposed to predict the in-plane strength of CFST parabolic truss arches under uniformly distributed loads.