• Advanced Composite Materials
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• 제17권4호
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• pp.343-358
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• 2008

This present study provides the structural design and analysis of main wing, horizontal tail and control surface of a small scale WIG (Wing-in-Ground Effect) craft which has been developed as a future high speed maritime transportation system of Korea. Weight saving as well as structural stability could be achieved by using the skin.spar.foam sandwich and carbon/epoxy composite material. Through sequential design modifications and numerical structural analysis using commercial FEM code PATRAN/NASTRAN, the final design structural features to meet the final design goal such as the system target weight, structural safety and stability were obtained. In addition, joint structures such as insert bolts for joining the wing with the fuselage and lugs for joining the control surface to the wing were designed by considering easy assembling as well as more than 20 years service life.

• 한국구조물진단유지관리공학회 논문집
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• 제7권1호
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• pp.207-215
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• 2003

Developed is a new environment-friendly concrete-block retaining wall system. The conventional analysis methods are not directly applicable because the proposed concrete-block wall system is made of by interlocking the blocks with shear keys. Therefore, the shear analysis as well as stability analysis have been conducted to secure the safety of block-wall system. Overall slope stability analysis was also performed. An appropriate strengthening method was developed to ensure the safety when the block-wall system is relatively high. The method of analysis for strengthening the concrete-block wall system was also proposed. The proposed environment-friendly concrete block retaining wall system shows reasonable safety and can be a good construction method for retaining walls and river bank walls.

• 한국시뮬레이션학회논문지
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• 제29권2호
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• pp.95-103
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• 2020

본 논문에서는 경량구조 적용을 위한 구조 접합부 설계를 제시하였다. 압력에 대한 구조 안정성 연구를 위하여 용접부 접합부와 볼트 접합부에 대한 모델을 설계하였다. 확립된 모델의 신뢰성 검증을 위하여, 비선형 해석을 수행하였고, 실험결과와 비교하였을 때 유사한 결과를 확인하였다. 또한 비교연구를 통하여 구조설계 재료와 적합한 용접방법을 선택하였으며, 볼트의 개수와 위치에 따른 파단하중 시뮬레이션을 진행하여 응력에 따른 안정성을 분석하였다. 마지막으로, 접합부 모델을 기반으로 경량 구조를 모델링하고 구조 해석을 수행하였다. 그 결과, 용접부와 볼트체결을 적용하여 설계된 구조가 접합부를 적용하지 않은 구조에 비해 최대응력이 31.4% 감소함을 확인하였다. 이 결과를 토대로, 경량구조의 안정성 해석 시 접합부 모델링의 필요성을 확인하였다.

• 한국생산제조학회지
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• 제22권6호
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• pp.901-907
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• 2013

The development of high-rise firefighting vehicles warrants thorough structural analysis for ensuring vehicle stability. A few structural analyses were carried out using CAD data, material properties, load conditions, and boundary conditions for evaluating the structural stability of an overloaded multi-aerial platform for firefighting and rescue. Structural analysis was performed with an analytical model consisting of a turntable, six booms, two jib booms, and a basket structure. This model was operated in eight modes. All simulation was performed using NASTRAN, a commercial code. As a result, we confirm that the position of local stress exceeds that of the yield strength. Therefore, stress concentration relaxation is possible by introducing reinforcing boom structures, changing the shape, or imparting a larger moment of inertia to the booms' cross sections.

• Wind and Structures
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• 제13권5호
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• pp.471-485
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• 2010

In comparison with the common two-tower suspension bridge, due to the lack of effective longitudinal restraint of the center tower, the three-tower suspension bridge becomes a structural system with greater flexibility, and more susceptible to the wind action. By taking a three-tower suspension bridge-the Taizhou Bridge over the Yangtze River with two main spans of 1080 m as example, effects of structural parameters including the cable sag to span ratio, the side to main span ratio, the deck's dead load, the deck's bearing system, longitudinal structural form of the center tower and the cable system on the aerodynamic stability of the bridge are investigated numerically by 3D nonlinear aerodynamic stability analysis, the favorable structural system of three-tower suspension bridge with good wind stability is discussed. The results show that good aerodynamic stability can be obtained for three-tower suspension bridge as the cable sag to span ratio is assumed ranging from 1/10 to 1/11, the central buckle are provided between main cables and the deck at midpoint of main spans, the longitudinal bending stiffness of the center tower is strengthened, and the spatial cable system or double cable system is employed.

• Geomechanics and Engineering
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• 제27권6호
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• pp.551-560
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• 2021

Due to the low strength and high compressibility characteristics, the loess deposits tunnels are prone to large deformations and collapse. An accurate stability evaluation for loess deposits is of considerable significance in deformation control and safety work during tunnel construction. 37 groups of representative data based on real loess deposits cases were adopted to establish the stability evaluation model for the tunnel project in Yan'an, China. Physical and mechanical indices, including water content, cohesion, internal friction angle, elastic modulus, and poisson ratio are selected as index system on the stability level of loess. The data set is randomly divided into 80% as the training set and 20% as the test set. Firstly, principal component analysis (PCA) is used to convert the five index system to three linearly independent principal components X1, X2 and X3. Then, the principal components were used as input vectors for probabilistic neural network (PNN) to map the nonlinear relationship between the index system and stability level of loess. Furthermore, Leave-One-Out cross validation was applied for the training set to find the suitable smoothing factor. At last, the established model with the target smoothing factor 0.04 was applied for the test set, and a 100% prediction accuracy rate was obtained. This intelligent classification method for loess deposits can be easily conducted, which has wide potential applications in evaluating loess deposits.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.185-190
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• 2011

The important use of the desuperheater(multi spray type) changes the superheated steam into the saturated steam. It is more efficient and suitable for using the process. Also, it is more convenient and stable regarding the process temperature control. In this study, transient and quasi-static analysis were done for the evaluation of structural integrity of the multi spray type desuperheater of the power plant. Computational analysis was used to calculate the thermal stress, and the vibration test was done to evaluate the structural stability. This paper is verified by analysis that water spray nozzle(${\phi}=28mm$) shows the best ability. The results show that structural stability of the desuperheater under the real operating condition was proven.

• Advances in aircraft and spacecraft science
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• 제9권2호
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• pp.149-167
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• 2022

A Modified fuzzy mechanical control of large-scale multiple time delayed dynamic systems in states is considered in this paper. To do this, at the first level, a two-step strategy is proposed to divide a large system into several interconnected subsystems. And we focus on the damage propagation for aircraft structural analysis of composite materials. As a modified fuzzy control command, the next was received as feedback theory based on the energetic function and the LMI optimal stability criteria which allow researchers to solve this problem and have the whole system in asymptotically stability. And we focus on the results which shows the high effective by the proposed theory utilized for damage propagation for aircraft structural analysis of composite materials.

• 한국안전학회지
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• 제31권2호
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• pp.64-69
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• 2016

In this paper, structural analysis of High-Speed railway vertical tunnel structures was performed to verify the structural stability. The corrugated steel plate method was applied to the vertical tunnel structures for its simple construction method and low cost. The structural stability of Wall, Connection and Storage section was performed with LRFD and ASD design method at joint part, buckling, stress and plastic hinge. From the results, all of vertical tunnel structures shown the structural stability regardless of design method and structure types. So, the application of corrugated steel plate in vertical tunnel structures instead of cast-in-placed concrete was quite enough.

• 한국기계가공학회지
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• 제13권5호
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• pp.107-115
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• 2014

Highly functional mill turrets have been developed and continuously improved to shorten the manufacturing time and enable multiple uses. Among these, a mill turret with B-axis rotary table was developed. The B-axis rotary table should be evaluated for structural integrity. Moreover, its worm and worm gear for transmitting power should be able to endure fatigue damage. Therefore, this article presents a structural analysis of this type of B-axis rotary table and confirms its static stability by comparing the stress results to the allowable stress levels. Next, the dynamic stability of the rotary table was investigated via a mode analysis and a harmonic analysis in a range determined by the results of a modal analysis. Finally, a worm gear set, the main part that drives the rotary table, is analyzed for fatigue and to estimate its lifetime. The results of the fatigue analysis allowed a prediction of the life of the worm gear set. The analytical results show that the B-axis rotary table has good structural integrity.