• Journal of Aerospace System Engineering
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• v.18 no.5
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• pp.81-89
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• 2024

Recently, both volumes and weights of antennas are increasing because of advancement of satellite missions. Research studies on mesh deployable antennas that can be highly stowable and lightweight are also increasing. When a deployable mesh antenna is subjected to repeated deployment tests on the ground, vibration of launch environments can cause slip between the antenna structure and the mesh fabric, resulting in failure to maintain the surface curvature of the antenna and Openning Per Inch (OPI). Such failure is the main cause of RF performance and mission capability degradation. Thus, studying a fastening technique to prevent slip between the antenna structure and mesh fabric is essential. This study proposed a Clamping fastening technique using rivets between the antenna structure and the mesh fabric. To evaluate the fastening efficiency of the Clamping fastening technique, tensile tests were conducted according to antenna structure type and rivet increment. Results were analyzed and fastening efficiency of the proposed clamping fastening technique was verified.

• Computational Structural Engineering
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• v.6 no.4
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• pp.99-105
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• 1993

In this paper a useful method on evaluating the joint stiffness of a bolted member was introduced using optimization technique on the basis of Finite Element Method. A finite element model having one directional gap element at boundary area was introduced to compensate the prying force in jointed members which might be caused by geometrical configuration of members. Results showed a good agreement with classical method in certain range and will be available to define the appropriate design margin of pre-load design.

• 해운
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• no.8 s.41
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• pp.17-20
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• 2007

최근 해운시황의 호전으로 전세계적으로 해운시장에 많은 자금이 몰리고 있는 가운데 프랑스계은행이 한국의 관련 제도를 이용하여 선박금융을 체결, 세계해운업계의 이목을 끌고 있다. 특히 이러한 계약은 조선국가에서의 선진금융기법을 활용했다는 점에서 우리나라가 세계 선박금융의 새로운 시장으로 부각되고 있다. 다음은 로이드에서 발간하는 월간지 'Shipping Economist' 8월호 기사내용과 선박금융지원과 관련한 한국수출보험공사의 입장을 정리한 것이다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.417-418
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• 2010

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.11a
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• pp.29-29
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• 1997

각광 받는 구조재료인 섬유강화 복합적층재에 대한 기계적 체결 거동은 본질적인 재료의 이방성에 의해서 파단강도가 파단 모우드와 매우 밀접한 관련을 갖는 것으로 알려져 있다. 따라서, 복합적층판 체결부의 정밀 구조 설계에서는 단순화에 따른 오차를 줄이고 정밀해에 의한 설계 및 해석이 요청된다. 특히, 층간응력 성분을 무시할 수 없는 두께를 갖는 복합적층 판의 기계적 체결부 해석이나 실제 구조물의 체결부에서 발생하는 굽힘이나 비틀림과 같은 하중 상태를 묘사하기 위해서도 정밀한 3차원 응력 해석은 필요하다. 하지만, 지금까지 기계적 체결부의 거동에 관한 연구는 층간응력 성분들을 어느정도 무시할 수 있는 얇은 평판에 대한 2차원 응력해석에 주로 국한되어 왔으며, 일부 수행된 체결부에 대한 3차원 응력 해석의 경우 여러 단점을 갖는 3차원 연속체 요소에 의한 유한요소 해석이 수행되었을 뿐이다.본 연구는 층간응력 성분들을 무시할 수 없는 두께를 갖는 복합적층판의 기계적 체결부 해석에 지금까지 사용되어온 3차원 연속체 요소에 의한 유한요소 방법이 갖는 단점들을 개선한 Layerwise 유한요소법을 이용하여 3차원 응력해석을 수행하였다. 특히, 선형상보성원리에 근거한 최적설계 기법을 응용하여, 기계적 체결시 핀과 적층판의 홀 사이에 발생하는 하중 전달 과정을 모사하고, 접촉력에 의한 홀 주위의 복잡하고 국부적인 응력 집중현상을 규명하여본다.

• Journal of the Korean Geotechnical Society
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• v.31 no.3
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• pp.17-25
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• 2015

In this study, a new segment assembling method using cable tensible force and island-type shear key was developed to improve the problems of bolt assembling method of shield tunnel. The bolting system and island-type shear key system were compared to analyze the mechanical behavior that occurs in the segment. The study results obtained from structural investigation and numerical analysis technique showed that the shear strength of island-type shear key is higher than that of the bolt system. With the increase of the tensile strength, it is expected that the stability of the segment will be secured.

• Journal of the Korean Society for Railway
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• v.18 no.1
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• pp.43-52
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• 2015

In this study, to minimize both the costs associated with track maintenance and the energy consumption for train operation, a numerical method that evaluates the optimal vertical stiffness of a fastener for concrete track is presented. A progress model of the track damage is established in order to calculate the concrete track maintenance cost according to the fastener stiffness. Also, the quantitative relationship between the progress of the track damage and the maintenance of the concrete track is derived. The wheel load is more exactly evaluated by using the advanced vehicle-track interaction model, which can precisely consider the behaviors of the track components. An optimal range for the stiffness of the fastener, a range that is applicable to the design of concrete track for domestic high speed lines, is proposed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.7
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• pp.765-770
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• 2014

This paper describes the study on a method for improving the structural durability of bolted joints applied to a composite bogie frame. In this study, three bolted joints with and without inserts and screw threads were selected for determining the effect of the inserts, using experiment and analysis. The structural performances of the proposed bolted joints were compared and evaluated using the test method prescribed by the ASTM D5961 standard. The results revealed that the bolted joint having an insert shape without the screw thread offered improved durability for application to a composite bogie frame. Furthermore, the structural integrity of the frame comprising the bolted joints was evaluated using finite element analysis according to the JIS E 4207 standard. The Tasi-Wu and Von-Mises failure criteria were used for determining the failure of the composite structure and bolted joints, respectively. A sub-modeling technique was introduced for investigating the performance of the bolted joints in greater detail. The analysis results demonstrated that the Tasi-Wu failure index of the composite structure near the bolted joints was reduced by approximately one-half after applying an insert without the screw thread. This implies that the structural durability of the bolted joints of a composite bogie frame could be improved by using a metal insert without the screw thread.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.12
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• pp.994-1003
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• 2018

The clamping characteristics of segmented nuts in pyrotechnic separation nut are investigated using finite element analysis. When the segmented nuts are used to clamp objects, a constraint cylinder is necessary to prevent the segmented nuts from spreading out to the radial direction. During the manufacturing process, a clearance is usually introduced between the outer diameter of the segmented nuts and the inner diameter of the constraint cylinder. Therefore to find out the effect of the clearance, proper finite element modeling method is suggested to describe the clamping procedure appropriately. In addition, finite element analysis with the clearance of 0.00, 0.03, 0.06, and 0.10 mm are performed. From the analysis results, the clamping characteristics of segmented nuts are investigated according to the clearance, and several factors which should be considered to design a reliable pyrotechnic separation nut are figured out.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.6
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• pp.1-12
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• 2016

There is growing concern about landscape agreement with regard to a variety of activities within resident-based agreements in Korea. This study aims to investigate the communication method of the agreement contacting process and its essential role as a bottom-up resident-based process. The study site is Gobuk Market in Suwon city, where a resident-based landscape agreement was successfully made. In this study, the author implemented in-depth interviews and a literature review to understand the meaning of the agreement contracting process and participants' opinions regarding the Gobuk Market case. During the landscape contracting process, the level of participation of residents, experts and the government changed. The study found that diverse communication methods, such as training, agreement information sessions and seminars were conducted during the process of the resident-based landscape agreement and it is crucial to construct healthy relationship among stakeholders. Furthermore, the experts' role is crucial in establishing agreement among residents initially. However, as local empowerment and the willingness of local people grow, each stakeholder's role is changed by stage. Therefore the Central and Local Government have the necessary task of providing institutional strategy. This study has offered practical information on how each stakeholder played their individual role within the landscape agreement.