• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.12
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• pp.1101-1104
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• 2008

We have studied electro-optic characteristics to improve viewing angle of the in-plain switching (IPS) liquid crystal display using an compensation film. The IPS mode shows relatively large light leakage and color shift in diagonal directions in a dark state. To solve this problem, we have compensated the low contrast ratio in diagonal directions using one optimized discotic film and adjusting TAC films of polarizers. The compensated IPS mode shows wide viewing angle characteristics that region of CR 50:1 is over $60^{\circ}$ of polar angle in all directions. The optimized IPS cell exhibits much better performances than other methods do in terms of CR and color uniformity.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.178-185
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• 2000

A set of tests were accomplished in order to get better insight of the basic material properties of masonry made of normal concrete brick and different type of mortar compositions. Three different types of test were performed. Masonry unit and prism were tested by compressive strength test, Masonry wallets were tested by compressive strength test. Masonry wallets were tested in diagonally under tension. A significant influence of different mortar compositions on compression strength of masonry prism was observed, The tests have shown that for diagonal compression three different mode of failure were possible : tension crack along the loaded diagonal sliding along a mortar joint and combined sliding and diagonal crack according to the adhesive strength of a mortar.

• Journal of Ocean Engineering and Technology
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• v.21 no.6
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• pp.7-15
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• 2007

A mechanical model was developed to predict the behavior of point-loaded RC slender beams (a/d > 2.5) without stirrups. It is commonly accepted by most researchers that a diagonal tension crack plays a predominant role in the failure mode of these beams, but the failure mechanism of these members is still debatable. In this paper, it was assumed that diagonal tension failure was triggered by the concrete cover splitting due to the dowel action at the initial location of diagonal tension cracks, which propagate from flexural cracks. When concrete cover splitting occurred, the shape of a diagonal tension crack was simultaneously developed, which can be determined from the principal tensile stress trajectory. This fictitious crack rotates onto the crack tip with load increase. During the rotation, all forces acting on the crack (i.e, dowel force of longitudinal bars, vertical component of concrete tensile force, shear force by aggregate interlock, shear force in compression zone) were calculated by considering the kinematical conditions such as crack width or sliding. These forces except for the shear force in the compression zone were uncoupled with respect to crack width and sliding by the proposed constitutive relations for friction along the crack. Uncoupling the shear forces along the crack was aimed at distinguishing each force from the total shear force and clarifying the failure mechanism of RC slender beams without stirrups. In addition, a proposed method deriving the dowel force of longitudinal bars made it possible to predict the secondary shear failure. The proposed model can be used to predict not only the entire behavior of point-loaded RC slender shear beams, but also the ultimate shear strength. The experiments used to validate the proposed model are reported in a companion paper.

• Journal of the Korean Magnetic Resonance Society
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• v.10 no.1
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• pp.59-73
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• 2006

Spin-lattice relaxation pathway of $CH_2$ spin system by two dimensional NOESY sequence has been discussed. Two-dimensional spectra governed by dipolar relaxation mechanism were simulated in term of transfer mode, the generalization of conventionally used magnetization mode in one dimension. The transfer matrix directly related to the Redfield relaxation matrix can be constructed by the multiplet of transfer mode. The observable relaxation transfer modes causes to variation of the off-diagonal signal intensity of phase sensitive NOESY spectra from which variable spectral density can be extracted with simple group theoretical calculation. The variation of the J-coupling peak intensity as a function of the mixing time in 2-D spectra for $n-Undecane-5-^{13}C$ and Bromoacetic $2-^{13}C$ acid has been theoretically traced.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.1
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• pp.1-10
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• 2007

Three dimensional structures of detonation waves propagating in a square tube were investigated using a high resolution CFD code coupled with a conservation equation of reaction progress variable and an one-step irreversible reaction. The code were parallelized based on domain decomposition technique using MPI library. The computations were carried on an in-house Windows cluster with AMD processors. Three-dimensional unsteady analysis results in the smoked-foil records caused by the instabilities of the detonation waves, which showed the rectangular and diagonal modes of detonation instabilities depending on the initial condition of disturbances and the spinning detonation for case of small reaction constant.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.321-324
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• 2005

This paper presents a preliminary study on the influence of material ductility on diagonal tension behavior of shear-wall panels. There have been a number of previous studies, which suggest that the use of high ductile material such as ECC (Engineered Cementitious Composite) significantly enhanced shear capacity of structural elements even without shear reinforcements involved. The present study emphasizes increased shear capacity of shear-wall panels by employing a unique strain-hardening ECC reinforced with poly(vinyl alcohol) (PVA) short random fibers. Normal concrete was adopted as the reference material. Experimental investigation was performed to assess the failure mode of shear-wall panels subjected to knife-edge loading. The results from experiments show that ECC panels exhibit a more ductile failure mode and higher shear capacity when compared to ordinary concrete panels. The superior ductility of ECC was clearly reflected by micro-crack development, suppressing the localized drastic fracture typically observed in concrete specimen. This enhanced structural performance indicates that the application of ECC for a in-filled frame panel can be effective in enhancing seismic resistance of an existing frame in service.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.89-92
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• 2008

This study investigates the shear behavior of architectural masonry veneer wall reinforced with specific reinforcement details proposed by this study. For this purpose, experimental tests were conducted using one un-reinforced masonry(URM) wall specimen and three reinforced masonry(RM) wall specimens under quasi static cyclic loads. Un-reinforced(plain) masonry wall is expressed that behavior and failure mode are different for aspect ratio(L/H) and axial compressive force. The test variables are wall aspect ratio and presence of reinforcement. These specimens are masonry structure for architectural clading that is not to exist the axial compressive force. thus the axial compressive force is excepted from test variable. Test result, Behavior of specimens are dominated over rocking mode, but final failure modes are combined with different behaviors. And FEMA273 has proposed the equation of shear strength of masonry pier subjected to in-plane loading. Shear strength equations are classified four types of failure mode that is Rocking, and Toe-Crushing, Bed-Joint-Sliding and Diagonal-Tension. FEMA273 equations predict the behavior modes well, but shear strength is shown in different result.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.181-185
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• 2007

A free-surface correction(FSC) method is presented to solve the 3-D shallow water equations. Using the mode splitting process, FSC method can simulate shallow water flows under the hydrostatic assumption. For the hydrostatic pressure calculation, the momentum equations are firstly discretized using a semi-implicit scheme over the vertical direction leading to the tri-diagonal matrix systems. A semi-implicit scheme has been adopted to reduce the numerical instability caused by relatively small vertical length scale compare to horizontal one. and, as the free surface correction step the final horizontal velocity fields are corrected after the final surface elevations are obtained. Finally, the vertical final velocity fields can be calculated from the continuity equation. The numerical model is applied to the calculation of the simulation of flow fields in a rectangular open channel with the tidal influence. The comparisons with the analytical solutions show overall good agreements between the numerical results and analytical solutions.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.04a
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• pp.72-77
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• 1990

Results are presented of the cyclic loading tests of there low-rise shear wall assembligies using high strength concrete. The possibilities of achieving an acceptable level of energy dissipation in one story shear walls, mainly by flexural yielding, are examined. Mechanisms of flexural and shear resistance are reviewed with emphasis on aspects of sliding shear. Detrimental effects of sliding shear are demonstrated together with improvement achieved by use of diagonal wall reinforcements. It is postulated that with suitably arranged diagonal wall reinforcements a predominantly flexural response mode with good energy dissipation characteristics can be achieved in low-rise shear walls.

• Structural Engineering and Mechanics
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• v.19 no.3
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• pp.237-260
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• 2005

This paper presents an experimental as well as a numerical analysis of the in-plane shear behaviour of hollow, $870{\times}840{\times}100mm$ masonry walls, externally strengthened with FRP composites. The experimental approach is devoted to the evaluation of the effectiveness of different composite strengthening configurations and the methodology consists in the diagonal compression of masonry walls. The numerical study assesses the stress and strain state distribution in the unreinforced and strengthened panels using a commercial finite element code. The effect of FRP reinforcement on the masonry behaviour and the capability of modelling to forecast a representative failure mode of the unreinforced and reinforced masonry walls is investigated.