• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.828-833
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• 2003

In this paper, a study on fracture characteristics of chemically prestressed mortar with addition of expansive additives was carried out. Uni-axial tension tests with reinforced mortar specimen restrained by embedded reinforcing bar and three point bending tests with notched steel fiber reinforced beams were carried out to verify the characteristics of the cracking behavior, the tension stiffening effect due to bond between rebar and mortar, and fracture characteristic. Tension stiffening curve for the chemically prestressed mortar was obtained from uni-axial tension test. And increased fracture energy due to the chemical prestress was also obtained from bending test and tension softening curve for chemically prestressed mortar was also obtained.

• Structural Engineering and Mechanics
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• v.65 no.3
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• pp.251-261
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• 2018

Self-centering concentrically braced frames (SCCBFs) are emerging as high performance seismically resistant braced framing system, due to the capacity of withstanding strong earthquake attacks and promptly recovering after events. To get a further insight into the seismic performance of SCCBFs, systematical evaluations are currently conducted from the perspective of modal contributions. In this paper, the modal pushover analysis (MPA) approach is utilized to obtain the realistic seismic demands by summarizing the contribution of each single vibration mode. The MPA-based results are compared with the exact results from nonlinear response history analysis. The adopted SCCBFs originate from existing buckling-restrained braced frames (BRBF), which are also analyzed for purpose of comparison. In the analysis of these comparable framing systems, interested performance indices that closely relate to the structural damage degree include the interstory drift ratio, floor acceleration, and absorbed hysteretic energy. The study shows that the MPA approach produces acceptable predictions in comparison to the exact results for SCCBFs. In addition, the high-modes effect on the seismic behavior increases with the building height, and is more evident in the SCCBFs than the BRBFs.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.465-472
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• 1998

In this study, analytic solution and finite element formulation for the free vibration analysis of thin-walled circular arch, based on linearized virtual work and Vlasov's assumption, including restrained warping effect and second order terms of finite semitangential rotations, is presented. The total potential energy is derived by applying the Hellinger-Reissner principle. In this formulation, all displacement parameters of deformation are defined at the centroid axis. For the finite element formulation, the two node cubic Hermitian polynomials are utilized as shape functions. In special case, potential energy functional of thin-walled curved beam with monosymmetric cross section is derived. From this methodology, analytic solution for the free vibration of monosymmetric circular arch with simply supported is derived. In order to illustrate the accuracy of this study, various parameter studies for free vibration of circular arches are presented and compared with numerical solution analyzed by the FEM using straight beam element.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.4
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• pp.937-945
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• 1996

Nitrous oxide has acquired widespread use as a tool for management of anxious and comprehensive pediatric dental patients. Clinical impressions have suggested that inhalation sedation with $N_2O/O_2$ reinforces the effect of other sedatives. Fifteen uncooperative children, mean age of 37months, who were regarded as fail in the first treatment using chloral hydrate-hydroxyzine orally, midazolam orally or intranasally, were sedated with the same sedatives in conjunction with $N_2O/O_2$. All the children were restrained in a pediwrap and were monitored with pulse oximeter for their heart rate and oxygen saturation. Degree of sleep, crying and movement were evaluated. The clinical results indicated that a satisfactory level of sedation was achieved in approximately two thirds of the cases (about 66 %) under those sedation manner. Complications were rare and those of treatments were successfully completed without difficulty.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.186-187
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• 2014

Flexural stress and fracture energy of fiber reinforced cementitious composites is increased by bridge effect of reinforced fiber, scabbing failure is restrained. Shape, properties of fiber were SF(steel fiber), PA(polyamide), NY(nylon) have effects on flexural stress and fracture energy, impact resistance improve of fiber reinforced cementitious composites. In this study, local failure properties by impact of high velocity projectile was analyzed by mixing 3 types of fiber which have different shape and properties respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.9
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• pp.635-640
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• 2010

This study is suggested tilt window type to be restrained solar radiation through vertical window type in buildings. The shading and aesthetical effect of buildings would be solved by installation of tilt window type. For investigate optimum an angle of tilt window and building azimuth in reference region, the distance of transmitted solar radiation is calculated. The results of calculation showed optimum an angle of tilt window is obtained $7^{\circ}$ that the distance of transmitted solar radiation is 20% of 1.5m of balcony width. In case of an tilt window angle of $7^{\circ}$, the optimum building azimuth is showed $SW15^{\circ}{\sim}SE15$.

• Food Science and Preservation
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• v.5 no.2
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• pp.111-117
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• 1998

Biochemical property changes of garlic during various storages and marketing after storage were investigated. Content of enzymatic pyruvic acid increased by room and low temperature storage but decreased by CA and MA storage. Fructan contents decreased rapidly by low temperature storage, but restrained decrement by CA and MA storage. Free sugar increased during storage, but did slowly by room temperature storage. Green pigment development was observed when garlics stored for 90days at low temperature were processed into crushed form. This discoloration was small for garlics stored in CA and MA, and never occurred for room temperature stored garlics. When marketed after storage, content of enzymatic pyruvic acid decreased in garlic stored in room and low temperature storage, but increased in garlics which decreased during CA and MA storage. Fructan contents deceased but free sugar contents continuously increased with marketing period. Green pigment development decreased in crushed garlic after 30days at room temperature marketing, but increased in low temperature marketing with marketing time progress.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.3
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• pp.290-296
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• 2005

The contour method is based on the elastic superposition principle, and relies on deformations that occur when a residually stressed part is cut along a plane. During the cut, the part is constrained at a location along the cut so that deformations are restrained as much as possible. The displacement is applied to an elastic FE model of the half. When plasticity is involved in the relaxation process, the superposition principle is no longer valid, and stress error in the resulting measurement of residual stress would be caused. Residual stress states in a laser peened Ti-6Al-4V strip were taken for the FE simulation.

• Steel and Composite Structures
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• v.24 no.6
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• pp.697-709
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• 2017

The current study addresses the local buckling analysis of an infinite thin rectangular symmetrically laminated composite plate restrained by a tensionless Winkler foundation and subjected to uniform in-plane shear loading. An analytic method (i.e., one-dimensional mathematical method) is used to achieve the analytical solution estimate of the contact buckling coefficient. In addition, to study the effect of ply angle and foundation stiffness on the critical buckling coefficients for the laminated composite plates, the parametric studies are implemented. Moreover, the convergence for finite element (FE) mesh is analysed, and then the examples in the parametric study are validated by the FE analysis. The results show that the FE analysis has a good agreement with the analytical solutions. Finally, an example with the analytical solution and FE analysis is presented to demonstrate the availability and feasibility of the presented analytical method.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.237-238
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• 2021

This study evaluated the vapor pressure and thermal stress of high-strength concrete according to spalling type. As a result, it was confirmed that the internal temperature gradient of the concrete varies depending on the heating rate, and the vapor pressure and thermal stress of the concrete are the main factors of spalling. In addition, it was confirmed that spalling type varies depending on the vapor pressure and thermal stress of the concrete.