• Nuclear Engineering and Technology
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• v.27 no.3
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• pp.327-335
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• 1995

The normal shutdown and maintenance period of a nuclear power plant can be remarkably shortened when the examination and maintenance works in steam generator tubes are simultaneously carried out with refueling job. There are nozzle dams to Hock the coolant How from reactor to steam generator. Workers are reluctant to install nozzle dam because of the high radiation exposure and the limited working space in steam generator. Moreover, the heavy weight of present nozzle dam makes it installation and removal works much difficult. In this paper, a lighter KAERI nozzle dam with increased flexural rigidity-to-weight was designed and manufactured by changing the structure design of the present nozzle dam and by selecting new material, carbon fiber-reinforced plastic.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.93-102
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• 2007

A large number of FRP decks are already in service worldwide because the lighter FRP-based bridge decks are ideal for rapid construction to reduce the dead load of superstructures. And the proper design process is demanded for the effective FRP deck application. In this paper, to get the basic prototype of FRP bridge decks, the ratio of individual parameters, which compose the specification of FRP bridge decks, are determined by a finite element analysis. In addition, optimum FRP deck shapes are determined considering complex constraints and material properties of bi-directional characteristics. Upon these results, the prototype of FRP bridge decks is validated.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.11a
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• pp.17-20
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• 2006

It often happen water leakage that roof membrane have a poor condition such as direct exposed to rain, ultraviolet lays, temperature change compare with other part of waterproofing. There are difficult to maintain the quality of waterproofing and durability due to use only few waterproofing materials in practical in spite of development and use the various waterproofing material as solution of these poor condition. Therefore, in this thesis, I would like to know the property to apply field and suggest other method to develop for this waterproofing method to adopt various field condition for roof tops, as searching exposed and complex waterproofing technology for roof tops which is reinforced sheet using rising system have a regular pitch, depth, space.

• Journal of Aerospace System Engineering
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• v.9 no.4
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• pp.55-61
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• 2015

In this study, we peformed optimal design of a composite skid landing gear, one of the solid spring shock absorbers, for light vertical takeoff and landing aircraft. Although a solid spring type has poor energy dissipation capability, it is commonly used for light aircraft where sink speeds are low and shock absorption is non-critical in terms of simplicity, low cost and weight reduction. In this paper, design parameters of solid spring such as sink speed, gear leg length, deflection and landing load factor were reviewed. In order to meet structural requirements such as deflection and strength, finally, we conducted optimal design of the composite skid landing gear for VTOL UAV using genetic algorithm and pattern search algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7878-7884
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• 2015

Marine sea water pump with impeller using carbon fiber block was developed to prevent the impeller corrosion by the salinity. A numerical analysis was carried out in order to optimize the impeller and volute design for marine sea water pump and to investigate the sensitivity of the related parameters(impeller thickness, surface roughness) using CFD commercial code. The impeller thickness is limited because of the weight. Since the impeller using the carbon fiber lights, the thickness which has a maximum efficiency can be used. The results show that the surface roughness leads to an 7% reduction in pump efficiency.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1345-1346
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• 2006

본 논문에서는 솔레노이드 형태의 칩 인덕터와 나선형태의 박막 인덕터에 대하여 주파수 특성을 비교 분석하여 장 단점을 정의하고자 한다. 솔레노이드형 RF 칩 인덕터는 $1.0mm{\times}0.5mm{\times}0.5mm$의 크기에 11nH의 인덕턴스를 가질 수 있도록 6회 권선하였다. 나선형 박막 인덕터는 $213{\mu}m{\times}250{\mu}m{\times}304{\mu}m$의 크기에 11nH의 인덕턴스를 가질 수 있도록 7회 권선하였다. 시뮬레이션을 위하여 AnSoft사의 HFSS를 이용하였으며, 이 결과 솔레노이드형 RF 칩 인덕터는 2GHz에서 77 정도의 품질계수와 5.6GHz의 SRF를 가진다. 반면 나선형 박막 인덕터는 2GHz에서 14 정도의 품질계수와 4.5GHz의 SRF를 가진다. 성능면에서는 솔레노이드형 RF 칩 인덕터가 우수한 특성을 나타내었으나 크기를 감소시키는데 제한을 받으므로, 향후 소형 경량화를 위하여 박막 인덕터의 개발은 필수적이며, 성능을 더욱 향상시키기 위하여 나선형태와 재료의 개발이 필수적이라 하겠다.

• Journal of the Korea Institute of Building Construction
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• v.6 no.4 s.22
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• pp.69-75
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• 2006

It often happen water leakage that roof membrane have a poor condition such as direct exposed to rain, ultraviolet lays, temperature change compare with other part of waterproofing. There are difficult to maintain the quality of waterproofing and durability due to use only few waterproofing materials in practical in spite of development and use the various waterproofing material as solution of these poor condition. Therefore, in this thesis, I would like to know the property to apply field and suggest other method to develop for this waterproofing method to adopt various field condition for roof tops, as searching exposed and complex waterproofing technology for roof tops which is reinforced sheet using rising system have a regular pitch, depth, space.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.152-158
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• 2005

Inner structured and bonded panel, or ISB Panel, as a kind of sandwich type panel, has metallic inner structures which have low relative density, due to their dimensional shape of metal between a pair of metal skin sheets or face sheets. Previous works showed that ISB panels containing inner structures formed as repeated pyramidal shapes saved weight up to $60\%$ in condition of same stiffness comparing with solid sheet. In this work, woven metal is adapted to inner structures replacing pyramidal structures. The test specimens of ISB panel containing woven metal made by multi-point electric resistance welding and 3-point bending test have been carried out. The results of experiments and comparisons of process parameters, stiffness and failure mode are discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.42-47
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• 2021

Recently, many structures using lightweight materials have been developed. This study was conducted by using Al6061-T6 and carbon fiber reinforced plastic (CFRP), two common lightweight materials. In addition, the failure characteristics of an interface bonded between a single material and a heterogeneous bonding material were analyzed. The specimens bonded with CFRP and Al6061-T6 were utilized by the combination of the heterogeneous bonding material. The specimens had a double cantilevered shape and the bonding between the materials was achieved by applying a structural adhesive. The experiments were conducted in opening mode: the lower part of the samples was fixed, while their upper part was subjected to a forced displacement of 3 mm/min by using a tensile tester. Under the tested amount of strength, energy release rate, and considering the specimens' fracture characteristics in opening mode, the specimen "CFRP-Al" presented the maximum stress, followed by "Al" and "CFRP". We can hence conclude that the inhomogeneous material "CFRP-Al" is useful for the construction of lightweight structures bonded with structural adhesive.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.64-73
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• 2022

This study aimed to design a 3D fairing shape to reduce the air resistance of commercial vehicles. Rankine Half Body was applied to design the fairing shape, and the design was verified through aerodynamic analysis. Aerodynamic loads were calculated considering the speed conditions of commercial vehicles and gust conditions to ensure the structural safety of the fairing. A glass fibre/epoxy composite material was used to design a fairing structure that satisfied the safety factor 3. The structural safety of the lightest fairing was confirmed through structural analysis.