• Proceedings of the KSME Conference
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• 2007.05a
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• pp.96-101
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• 2007

A new metallic sandwich panel with a quasi-Kagome truss core subjected to bending load has been analyzed. First, equations of the failure loads corresponding to the eight failure modes are presented. Then, non-dimensional forms of the equations are derived as functions of three geometric variables, one material parameter (yield strain), one load index and one weight index. Failure maps are presented for a given weight index. By using the dimensionless forms of equations as the design constraints, two kinds of optimization are performed. One is based on the weight, that is, the objective function, namely, the dimensionless load is to be maximized for a given weight. Another is based on the load, that is, the dimensionless weight is to be minimized for a given load. The results of the two optimization processes are found to agree each other. The optimized geometric variables are derived as a function of given weights or failure loads. The performance of the quasi-Kagome truss as the core of a sandwich panel is evaluated by comparison with those of honeycomb cored and octet truss cored panels

• Steel and Composite Structures
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• v.17 no.6
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• pp.907-927
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• 2014

Ultra-lightweight cement composite (ULCC) with a compressive strength of 60 MPa and density of $1450kg/m^3$ has been developed and used in the steel-concrete-steel (SCS) sandwich structures. ULCC was adopted as the core material in the SCS sandwich composite beams to reduce the overall structural weight. Headed shear studs working in pairs with overlapped lengths were used to achieve composite action between the core material and steel face plates. Nine quasi-static tests on this type of SCS sandwich composite beams were carried out to evaluate their ultimate strength performances. Different parameters influencing the ultimate strength of the SCS sandwich composite beams were studied and discussed. Design equations were developed to predict the ultimate resistance of the cross section due to pure bending, pure shear and combined action between shear and moment. Effective stiffness of the sandwich composite beam section is also derived to predict the elastic deflection under service load. Finally, the design equations were validated by the test results.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2785-2796
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• 2023

How to generate the precise broad group cross section is important for the fast reactor design. In this study, a fast reactor multi-group cross-section generation code MGGC2.0 are developed in-house for processing ultrafine group MATXS format library. Validation and verification are performed for MGGC2.0 code by applying the benchmarks of ICSBEP handbook, and the results of MGGC2.0 agree well with that of MCNP. The consistent P_N method with critical buckling search is in good agreement that condensed with TWODANT flux and flux moment for the inner core and outer core region. For the radial blanket and reflector, two region approximation method has been applied in MGGC2.0 by using collision Probability Method neutron flux solver. The RBEC-M benchmark was used to verify the power distribution calculation, and the relative error of power distribution comparison with the reference are less than 0.8% in the fuel region and the maximum relative error is 5.58% in the reflector region. Therefore, the precise broad cross section can be generated by MGGC2.0 for fast reactor.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.73.1-73.1
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• 2016

We present preliminary results of the submillimeter continuum observations of 14 Planck Galactic Cold Clumps (PGCCs), located in the ${\lambda}$ Orionis Complex. This region is the nearest large HII region, which is an ideal site for a study of the stellar feedback to its surroundings. We observed 14 PGCCs with JCMT/SCUBA-2 and used J=1-0 transitions of CO isotopologues from the PMO mapping observation. Several sub-clumps toward three PGCCs were detected at $850{\mu}m$. In order to examine whether these clumps can be candidates for pre-stellar cores, we compared each clump mass calculated from the $850{\mu}m$ continuum map to its Virial mass and Jeans mass calculated from the $^{12}CO$ and $C^{18}O$ (1-0) spectra, respectively. All clumps have masses smaller than their Virial and Jeans masses, indicating that none of them are gravitational bound and thus in the pre-stellar core stage. Also, the CO depletion factor, which has been derived from the dust continuum and the $C^{18}O$(1-0) line and can be an indicator of core evolution, toward the clumps is in the range of 1 to 5, suggesting that they are not very evolved dense pre-stellar cores. In addition, within individual PGCCs, we found clear gradients of velocity (${\sim}1km\;s^{-1}\;pc^{-1}$) and temperature (${\sim}10K\;pc^{-1}$) in the $^{13}CO$ (1-0) first moment map and the $^{12}CO$(1-0) excitation temperature map, respectively. This can be attributed to the compression and external heating by the HII region, which may prevent clumps from forming gravitationally bound structures and eventually disperse clumps. These results could be a hint about the negative effect of stellar feedback on core formation.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.514-522
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• 2014

A new type of high precision electromagnetic suspension (EMS) which can support heavy tray along long stroke rail is proposed in this paper. Compared with the conventional EMS, the suggested moving-core typed EMS has the levitation electromagnets (EMs) on the fixed rail. This scheme has high load capability caused by iron-core and enables simple tray structure. Also it does not have precision degradation caused by heat generation from EMs, which is a drawback of conventional EMS. With these merits, the proposed EMS can be an optimal contactless linear bearing in next generation flat panel display (FPD) manufacturing process if the ability of long stroke movement is proved. So a special Section Switching Algorithm (SSA) is derived from the resultant force and moment equations of the levitated tray which enables long stroke movement of the tray. In order to verify the feasibility of the suggested SSA, a simple test-setup of the EMS with 2 Section-changes is made up and servo-controlled in the simulation and experiment. The simulation shows the perfect changeover the EMs, and the experiment shows overall control performance of under ${\pm}40{\mu}m$ gap deviations. These results reveal that the newly suggested contactless linear bearing can simultaneously achieve high load capability and precision gap control as well as long stroke.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.301-304
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• 2008

The stair joints constructed with prefabricated system are general method doing structure design at hinge. If you regarded joints to come in contact with a flight of stairs and a slope of stairs as hinge, the moment performance of joints is not in the least moment, so as the bending moment of the stair case is increased, the reinforcement increase. Also the use is decreased because increasing the joint damage of the vibration & fatigue load. No less the reason constructed with pin the stair joints because the construction efficiency of field work is useable. Recently, they are considering the construction efficiency, while the semi-rigid detail for bending performance of joints is proposed, but for now they don't reflect the detail. Therefore, we proposed that reflecting the method at design semi-rigid joints. We compared the moment performance with the stair joints designed at the rigid joints, semi-rigid joints and pin joints. The nonlinear behavior of staircase core statically indeterminate structure. The result of research is that a bending stiffness modulus bring to reflect the semi-rigid performance, the performance of the semi-rigid joint is better than pin joints, and that is judged the system better seismic and vibration performance because have excellent ductility more than rigid joint.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.493-498
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• 1998

An experimental investigation was conducted to examine the behavior of high-strength concrete R/C columns subjected to moment, shear and axial load. The test parameters of specimens were the compressive strength of concrete(f'c=250, 516, 600kg/ ㎠), space of lateral reinforcement (20, 30, 37cm) and lateral reinforcement ratio(ρs=2.1, 3.15%). Test results indicated that compressive strength of concrete and lateral reinforcement can significantly affect and alter the behavior of column under inelastic cyclic loadings. Despite of the defaults of high-strength concrete, with increased amount of lateral reinforcement ratio to core concrete and added sub-lateral reinforcement, ductility and strength of RC columns used high-strength concrete can secured.

• Magazine of the Korea Concrete Institute
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• v.5 no.1
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• pp.145-155
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• 1993

본 연구에서는 표면부를 에폭시 폴리머 모르터로 하고 , 중심부를 발포 폴리스티렌으로 하는샌드위치 패널을 제조하여, 표면부를 용접철강으로 보강한 경우와 보강하지 않은 경우에 대하여 4강 단순지지 조건에서의 정적 차 통해 하중-처짐, 휨모멘트-변형률, 파괴양상 등을 구명하였다. 단위중량, 극한가중, 휨모멘트는 중심부의 두께보다 표면부 두께에 더 큰 영향을 받으며 극한처짐은 보강안된 경우 표면부 보다 중심부 두께의 영향이 월등히 컸으마 보당된 경우는 표면부나 중심부 두께의 영향이 비슷하였다. 그러나 용접철망의 보강은 샌드위치 패널의 처짐억제 보다 인성증가에 기여도가 높은 것으로 나타났다. 샌드위치 패널의 파괴양상은 보강하지 않은 경우 선형파괴가 일어난데 비해 보강한 경우에는 방사상의 파괴가 일어났다.

• Transactions of Materials Processing
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• v.10 no.2
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• pp.91-100
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• 2001

A sectional FEA program is developed lot analyzing forming processes of sandwich sheets, which are intensively used recently as a lightweight material of an automobile body. The aluminum sandwich sheet consists of two aluminum skins and a polyprophylen core in between. The aluminum sandwich sheet is dominantly effected by the bending effects in small radius of curvature, so that an appropriate description of bending effects is required to analyze the forming processes. For the evaluation of bending effects, the bending equivalent forces are calculated from the bending moment computed using the curvature of the tool and are added to the membrane stretch forces. To verify the validity of the developed program the sectional FEA results in stretch/draw forming Processes of a square cup and draw forming Processes of an outer hood panel were compared with the measurements.

• Journal of The Korean Digital Architecture Interior Association
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• v.6 no.2
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• pp.31-38
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• 2006

An architect for Cultural Technology have the most obligation to improve the cultural inheritance into an industrial resources. From an esthetical point of view, it is possible to put digital contents to a multiplicity of practical usage in the moment of its' digital conversion. These are practical resources out of an only duplication from the original. Developing cultural archetype into the most suitable model for one-source multi-use that is the core of the project. If you want to change an archetype, a Korean traditional architecture, into a creative source, you should develope a reappearance and a practical model harmonized with the image set. In addition, development process of cultural archetype digital contents based on ultimate idea and imagnation in our architectural culture, referred from cultural archetype and digital contents technology was offered by the study.