• Magazine of the Korea Concrete Institute
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• v.14 no.4
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• pp.66-71
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• 2002

고유동 콘크리트는 높은 변형성과 분리 저항성에 의해 자기충전성을 갖는 콘크리트로서 외부에서 힘을 전혀 가하지 않거나 또는 아주 작은 힘만으로 재료분리 없이 거푸집 구석구석까지 충전되는 특징을 가진다. 이러한 고유동 콘크리트는 일본 동경대학의 강촌 보 교수에 의해 제창되었는데 콘크리트의 다짐을 하지 않아도 된다면 시공방법의 영향을 받지 않고 신뢰성이 높은 구조물을 만들 수 있을 뿐 아니라 1회치기 높이의 제한, 다짐작업을 위한 발판, 박스단면에서 밑면과 벽체 부분의 분할치기 등의 제약을 받지 않게 되고, 강 콘크리트 샌드위치 합성구조 등의 새로운 구조형식도 용이하게 시공할 수 있어 많은 이점을 가질 수 있다.(중략)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.666-669
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• 2004

Substructures position is considered as design parameter to obtain optimal structural changes to raise its dynamic characteristics. In conventional SDM (structural dynamics modification) method, the layout of modifying substructures position is first fixed and at that condition the structural optimization is performed by using the substructures size and/or material property as design parameters. But in this paper as a design variable substructures global translational and rotational position is treated. For effective structural modification the eigenvalue sensitivity with respect to that design parameter is derived based on measured frequency response function. The optimal structural modification is calculated by combining eigenvalue sensitivities and eigenvalue reanalysis technique iteratively. Numerical examples are presented to the case of beam stiffener optimization to raise the natural frequency of plate.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.95-110
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• 2010

A numerical model to simulate bond-slip behavior of composite beam bridges is introduced in this paper. Assuming a linear bond stress-slip relation along the interface between the slab and girder, the slip behavior is implemented into a finite element formulation. Adopting the introduced model, the slip behavior can be taken account even in a beam element which is composed of both end nodes only. Governing equation of the slip behavior, based on the linear partial interaction theory, can be determined from the force equilibrium and a constant curvature distribution across the section of a composite beam. Since the governing equation for the slip behavior requires the moment values at both end nodes, the piecewise linear distribution of the constant bending moment in an element is assumed. Analysis results by the model are compared with numerical results and experimental values, and load-displacement relations of composite beams were then evaluated to verify the validity of the proposed model.

• Journal of Korean Society of Steel Construction
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• v.26 no.5
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• pp.385-396
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• 2014

Traditionally, domestic steel design and construction practice has provided extra shear studs to moment frame beams even when they are designed as non-composite beams. In the 1994 Northridge earthquake, connection damage initiated from the beam bottom flange side was prevalent. The upward moving of the neutral axis due to the composite action between steel beam and floor deck was speculated to be one of the critical causes. In this study, full-scale seismic testing was conducted to investigate the side effects of the composite action in steel seismic moment frames. The specimen PN700-C, designed following the domestic connection and floor deck details, exhibited significant upward shift of the neutral axis under sagging (or positive) moment, thus producing high strain demand on the bottom flange, and showed a poor seismic performance because of brittle fracture of the beam bottom flange at 3% story drift. The specimen DB700-C, designed by using RBS connection and with the details of minimized floor composite action, exhibited superior seismic performance, without experiencing any fracture or concrete crushing, almost identical to the bare steel counterpart (specimen DB700-NC). The results of this study clearly indicate that the beams and connections in seismic steel moment frames should be constructed to minimize the composite action of a floor deck if possible.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.529-534
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• 2008

The normal shell and the regenerated oyster shell, Crassostrea gigas, are separated according to the characteristics of inner shell morphology. To study characteristics of chitin obtained from the regenerated shell, chitin prepared by acid and alkali process is analyzed by FT-IR (Fourier transform infrared spectrometer) and XRD (X-ray Diffractometer). The content of insoluble protein in the normal shell was more than doubled as compared with that in the regenerated shell. A comparison of secondary structure of the normal shell and the regenerated shell revealed that the content of random of the regenerated shell was above 47%, indicating an amount in the structural unordered state. Through amino acid composition analysis and secondary protein structure of soluble protein isolated from the normal shell and the regenerated shell, it was found that there are differences in biomineralization strategy of the regenerated shell as compared to the normal shell. The relatively low hardness of the regenerated shell is caused by the change of amino acid composition and ordered secondary protein structure as compared to hardness of the normal shell.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.174-186
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• 1991

There exist many frame structural systems which may be regarded as a combined structural system composed of beam/bar elements and attachments reducible to damped spring-mass systems. In this paper, analytical methods based on the receptance for the vibration analysis of such a system are presented. For the free vibration analysis and response calculations to point excitations, receptances of a uniform Timoshenko beam and a bar are derived in closed and spectral forms, and the method to obtain the system receptance by synthesizing the receptances of the elements and other subsystems is presented. The system damping property is also obtainable by sysnthesizing the components' damping properties. For calculations of the system responses to support motion, the Support Displacement Transfer Ratio(SDTR) of a uniform Timoshenko beam and a bar conceptually similar to the receptance is defined, and the method of synthesizing them with other subsystems' receptances is also presented. Such a method is very convenient especially in dynamic reanalysis subject to changes of some design variables.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3056-3068
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• 1996

This papre presents the RDM algorithm for composition of bit. After this, we propose a digital signature scheme for facsimile document using RDM algorithm. We modify the even-odd feature in distance of changing pel between coding line and multiple reference line which have been scanned before, and run-length in coding line. The time to take in signature is reduced by spreading of signature. Non-repudiation in origin, the 3rd condition of digital signature is realized by proposed digital signature scheme. The transmitter embeds the signature secretly and tensfers it, and the receiver makes a check of any forgery on the signature and the document. This scheme is compatible with the ITU-T.4(G3 or G4 facsimile standard). The total amount of data transmitted and the quality of image are about the same to that of the original document, thus a third party does not notics signature embeded on the document.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.134-139
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• 2005

This paper presents a robust design of vehicle interior noise using Taguchi method and a substructure synthesis method with a hybrid model. Firstly, the proposed method identifies the critical process of the concerned interior noise through a TPA (Transfer Path Analysis). Secondly, a strategy for a robust design is discussed, in which the major noise factor among uncertainties in the process is quality distribution of rubber bushes connecting a cradle and a trimmed body. Thirdly, a virtual test model fer the process is developed by applying a substructure synthesis method with a hybrid modeling approach. Fourthly, virtual tests are carried out according to the predefined tables of orthogonal array in Taguchi robust design process. The process was performed under 2 sub-steps. The first step is sensitivity analysis of 31 panels, and the other step is weight optimization of mass dampers on sensitive panels. Finally, two vehicles with the proposed countermeasures were validated. The proposed method reduces 87.5% of trials of measurements due to the orthogonal arrays and increases robustness by 8.6dB of S/N ratio and decreases $5\;dB(A){\sim}10\;dB(A)$ of interior noise in the concerned range of RPM.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.3
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• pp.454-463
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• 2000

A method is presented to alter the geometry of the conventional linearly shaped wire antenna for increasing its bandwidth. The synthesis is two-demensionally symmetric and is based on the minimization of frequency-dependence of the boresight far-field electric field intensity. The current distribution on the wire is calculated by Galerkin method using pulse functions. The shaping limitation for wide-band characteristics is still found because of standing waves due to reflected waves from antenna ends. The limitation overcome by a distribution of resistive loads near ends of wire. The antenna loaded resistively has flat characteristics satisfying a power gain of $6.5\pm1.1$dBi and VSWR of at most 2 over 10:1 bandwidth. The results are verified by comparing with similar results for the conventional linear V-dipole.

• Polymer(Korea)
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• v.37 no.2
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• pp.225-231
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• 2013

Poly(vinyl alcohol) (PVA) hybrid films containing 5 wt% pristine clay mineral were synthesized in the water solution. The various PVA hybrid films were synthesized from structurally different pristine clays: saponite (SPT), montmorillonite (MMT), hectorite (SWN), hydrophilic bentonite (PGV), and mica (Mica). The thermo-optical properties and morphologies of the PVA hybrid films were evaluated with various pristine clays. The nanostructure of the hybrid films was observed using transmission electron microscopy, which showed that the clay layers were well dispersed into the matrix polymer, although some clusters or agglomerated particles were also detected. The addition of pristine clay was more effective with regard to improving the thermal properties and gas barrier characteristics, whereas the optical transparency of the PVA hybrid films deteriorated with pristine clay.