• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.200-206
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• 2010

본 논문은 풍력발전 시스템의 하부 지지 구조물인 타워의 플랜지 연결부 설계 평가를 위한 플랜지 모델건전성 평가 기법에 대해 다룬다. 일반적으로 풍력발전 시스템 타워의 연결부는 Ring-형 플랜지의 형태를 가지고 있다. 이러한 ring-형 플랜지에 대한 설계 기준 및 방법은 풍력 발전 시스템 기술기준 등 에 명시되어있다. 이러한 설계 기준을 따르는 플랜지 연결부에 대해 구조 및 체결 볼트의 건전성 평가를 위해 하중평가 전용 프로그램인 GH-Bladed 3.8를 통해 생성된 하중 데이터를 유한요소 범용 프로그램인 Ansys 12.0에 접목하여 구조해석을 수행 하였다. 해석 방법은 풍력발전시스템의 타워를 셸 요소로 모델링하여 계산한 해석 결과를 플랜지 모델의 경계면에 적용 시켜 해석하는 submodeling 기법과 타워를 빔의 형태로 단순화 화여 계산한 거동 결과를 플랜지 모델에 적용하는 기법을 사용 하였다. 이 두 가지의 해석 기법으로 도출된 결과의 비교를 통하여 해석 결과 신뢰성을 평가하고 효율적이고 합리적인 방법을 제시하고자 하였다.

• Transactions of Materials Processing
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• v.12 no.2
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• pp.110-115
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• 2003

This paper is concerned with the compression test and forming process of flange by using virtual reality and analysis(simulation) program. This virtual manufacturing can be carried out one personal computer without any expensive devices for experiment. The virtual manufacturing composed of three modules such as the imput, calculation and the output modules on internet. Internet user can give the material's property and process parameters to the sever computer at the input module. On the calculation module, a simulator computes the virtual manufacturing process by analysis program and stores the data as a file. The output module is the program in which internet user can confirm virtual manufacturing results by showing tables, graphs, and 3D animation. This programs is designed by an internet language such as HTML, CGI, VRML and JAVA ,while analysis programs use the finite increasing, the virtual manufacturing technique will substitute many real experiments in the future.

• Structural Engineering and Mechanics
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• v.66 no.6
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• pp.713-727
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• 2018

Thin-walled mental tubes under lateral crushing are desirable and reliable energy absorbers against impact or blast loads. However, the early formations of plastic hinges in the thin cylindrical wall limit the energy absorption performance. This study investigates the energy absorption performance of a simple, light and efficient energy absorber called the ring stiffened tube. Due to the increase of section modulus of tube wall and the restraining effect of the T-stiffener flange, key energy absorption parameters (peak crushing force, energy absorption and specific energy absorption) have been significantly improved against the empty tube. Its potential application in the offshore blast wall design has also been investigated. It is proposed to replace the blast wall endplates at the supports with the energy absorption devices that are made up of the ring stiffened tubes and springs. An analytical model based on beam vibration theory and virtual work theory, in which the boundary conditions at each support are simplified as a translational spring and a rotational spring, has been developed to evaluate the blast mitigation effect of the proposed design scheme. Finite element method has been applied to validate the analytical model. Comparisons of key design criterions such as panel deflection and energy absorption against the traditional design demonstrate the effectiveness of the proposed design in blast alleviation.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.477-496
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• 2022

During a survey of free-living marine nematodes of Korea, two new marine desmoscolecid nematodes belonging to subgenus Quadricoma Filipjev, 1922 were discovered. Tricoma (Q.) jejuensis sp. nov. and T.(Q.) unipapillata sp. nov. are described based on specimens obtained from washings of coarse sediments from eastern and southern coasts of Korea. Tricoma (Q.) jejuensis sp. nov. is characterized by having 33 quadricomoid body rings and inversion at main ring 23, pentagonal head with truncated anterior end, a pair of ocelli situated at main ring 6, somatic setae comprising of 8 pairs of subdorsal setae and 12 pairs of subventral setae, and relatively short spicules (42-46 ㎛ long). Tricoma (Q.) unipapillata sp. nov. is characterized by 44 quadricomoid body rings and inversion at main ring 32, somatic setae comprising of 7 pairs of subdorsal setae and 10 pairs of subventral setae, globular head truncated anterior end, relatively short and stumpy cephalic setae with cuticular flange, one single naked ventral median genital papillae situated on main ring 20, and spicules with a proximally marked capitulum. Detailed morphological descriptions and illustrations of these two new species are provided in this study.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1613-1618
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• 2012

The wheel bearing is one of the important parts in a vehicle for translating power and bearing weight. When it is mounted on the knuckle by using bolts, the distortion of the outer ring including the seal mounting point and raceway occurs. In this study, a numerical analysis was performed to analyze the distortion of the outer ring by using a finite element method. The commercial software MSC.MARC was used for this purpose. Elastoplastic and contact analysis were carried out to compute the clamping behavior of the outer ring, bolts, and knuckle. Because the concavity on the flange of the outer ring affects the deformation, its effect was considered. To verify the reliability of this study, the roundness of the outer ring was measured. The experimental results were comparatively in agreement with the computational results.

• Nuclear Engineering and Technology
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• v.48 no.2
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• pp.533-544
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• 2016

This paper provides a reference to determine the seal performance of metallic O-rings for a reactor pressure vessel (RPV). A nonlinear elastic-plastic model of an O-ring was constructed by the finite element method to analyze its intrinsic properties. It is also validated by experiments on scaled samples. The effects of the compression ratio, the geometrical parameters of the O-ring, and the structure parameters of the groove on the flange are discussed in detail. The results showed that the numerical analysis of the O-ring agrees well with the experimental data, the compression ratio has an important role in the distribution and magnitude of contact stress, and a suitable gap between the sidewall and groove can improve the sealing capability of the O-ring. After the optimization of the sealing structure, some key parameters of the O-ring (i.e., compression ratio, cross-section diameter, wall thickness, sidewall gap) have been recommended for application in megakilowatt class nuclear power plants. Furthermore, air tightness and thermal cycling tests were performed to verify the rationality of the finite element method and to reliably evaluate the sealing performance of a RPV.

• International Journal of High-Rise Buildings
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• v.7 no.3
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• pp.223-232
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• 2018

Two novel types of construction detailings, including using the distributive beam and the inner ring diaphragm in the joint between large-section CFT columns and outrigger truss to enhance the transferring efficiency of huge vertical load, and using the T-shaped stiffeners in the steel tube of large-section CFT columns to promote the local buckling capacity of steel tubes, were tested to investigate their working mechanism and design methods. Experimental results show that the co-working performance between steel tube and inner concrete could be significantly improved by setting the distributive beam and the inner ring diaphragm which can transfer the vertical load directly in the large-section CFT columns. Meanwhile, the T-shaped stiffeners are very helpful to improve the local bulking performance of steel tubes in the column components by the composite action of T-shaped stiffeners together with the core concrete under the range of flange of T-shaped stiffeners. These two approaches can result in a lower steel cost in comparison to normal steel reinforced concrete columns. Finally, a practical engineering case was introduced to illustrate the economy benefits achieved by using the two typical detailings.

• Journal of Wind Energy
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• v.15 no.2
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• pp.23-36
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• 2024

In this study, a health monitoring system was developed for the two most vulnerable parts of a wind tower support structure: the connection between steel towers (L-Flange) and the concrete foundation-steel tower connection. To select assessment parameters for health monitoring, detailed FEM analysis was conducted using the ABAQUS program. Additionally, a testbed was established near the Jeju Woljeongri wind turbine farm to evaluate the applicability of measurement data by installing sensors. Through computational analysis and relevant criteria review, we defined limits for measurement parameters by vulnerable section. We categorized the structural safety evaluation into four stages: normal, caution, warning, and danger, and selected management criteria for each stage. From this, an algorithm to evaluate safety was developed, and a visualized monitoring platform based on the established critical parts monitoring system was developed.

• Journal of the Korean Institute of Gas
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• v.7 no.3 s.20
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• pp.51-57
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• 2003

This paper presents the temperature distribution and deformation characteristics of O-ring groove geometry in which is strongly related the sealing performance of pressure vessels. A working gas in pressure vessel may be heated by a heater and pressurized by a gas compressor. Thus, the pressure vessel should keep high Pressure and temperature for a limited working period. For these operation conditions, the working gas in pressure vessels should not leak to the air by two O-rings with a rectangular groove. The FEM computed results indicate that the thermal and mechanical properties of metal sealing material is very important for stopping a leakage of hot gas in a vessel. Based on the results, high thermal conductive and low mechanical strength material is recommended as a metal sealing one. This may improve the sealing characteristics of O-ring sealing mechanism with a rectangular groove, which reduces the sealing gap between a flange and a cylinder and the width of O-ring groove.

• Wind and Structures
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• v.21 no.6
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• pp.709-726
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• 2015

In this study, a novel vision-based bolt-loosening monitoring technique is proposed for bolted joints connecting tubular steel segments of the wind turbine tower (WTT) structure. Firstly, a bolt-loosening detection algorithm based on image processing techniques is developed. The algorithm consists of five steps: image acquisition, segmentation of each nut, line detection of each nut, nut angle estimation, and bolt-loosening detection. Secondly, experimental tests are conducted on a lab-scale bolted joint model under various bolt-loosening scenarios. The bolted joint model, which is consisted of a ring flange and 32 sets of bolt and nut, is used for simulating the real bolted joint connecting steel tower segments in the WTT. Finally, the feasibility of the proposed vision-based technique is evaluated by bolt-loosening monitoring in the lab-scale bolted joint model.