• Journal of Korean Association for Spatial Structures
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• v.5 no.4 s.18
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• pp.101-108
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• 2005

The investigations for mitigating wind-induced excitations of tall buildings have been carried out. The aerodynamic modification of a building shape changing the cross-section with height through tapering, which alters the flow pattern around the building, could reduce wind induced excitations of tall buildings. The fart that a tapered tall building might spread the vortex-shedding over a broad range of frequencies makes more effective for reducing acrosswind responses has been established. In this paper, to investigate the tapering effect for reducing wind-induced responses of a tapered tall building, high-frequency force-balance test was conducted. The six types of building models which have different taper ratio of 2.5%, 5%, 7.5%, 10%, 15% and one basic building model of a square cross-section were tested under the two typical boundary layers representing suburban and urban flow environment. The effect of wind direction was also considered.

• Wind and Structures
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• v.29 no.2
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• pp.111-127
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• 2019

The tapered and set-back type of unconventional designs have been used earlier in many buildings. These shapes are aerodynamically efficient and offer a significant amount of damping against wind-induced forces and excitations. Various studies have been conducted on these shapes earlier. The present study adopts a hybrid approach of turbulence modelling i.e., Detached-eddy Simulation (DES) to investigate the effect of height modified tapered and set-back buildings on aerodynamic forces and their sensitivity towards pressure. The modifications in the flow field around the building models are also investigated and discussed. Three tapering ratios (T.R.=(Bottom width- Top width)/Height) i.e., 5%, 10%, 15% are considered for tapered and set-back buildings. The results show that, mean and RMS along-wind and across-wind forces are reduced significantly for the aerodynamically modified buildings. The extent of reduction in the forces increases as the taper ratio is increased, however, the set-back modifications are more worthwhile than tapered showing greater reduction in the forces. The pressure distribution on the surfaces of the buildings are analyzed and in the last section, the influence of the flow field on the forces is discussed.

• The Journal of the Acoustical Society of Korea
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• v.17 no.4E
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• pp.22-27
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• 1998

A modified perturbation method is proposed to optimize the beam pattern of thinned microphone arrays. Both microphone spacing and array weight are iteratively adjusted via successive perturbation to achieve an optimum beam pattern in a Dolph Chebyshev sense. To improve the sidelobe performance, an alternative perturbation with respect to microphone spacing and array weight is implemented. Also, a linear space-tapering is employed in the perturbation process. It is demonstrated that the proposed approaches successfully yield sidelobe performances comparable to that of a normal array. Computer simulation results are presented.

• Journal of Microbiology
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• v.34 no.4
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• pp.379-383
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• 1996

Cryptosporidium parvum causes a life-threatening diarrhea in acquired immunodeficiency syndrome (AIDS) patients. THe sporozoite stage of C. parvum has been known to be a target in treating cryptosporidiosis in AIDS patients as it is an extracellular stage. A sporozoite was ultrastructurally observed. It has a creascent shape with a rounded posterior end and a tapering body. The compact nucleus was located at the posterior end. A monoclonal antibody was produced, which recognized a 43 kDa of sporozoite antigens in a western blot analysis and showed the surface labeling in immunofluorescence.

• Journal of Technologic Dentistry
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• v.15 no.1
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• pp.89-94
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• 1993

The tooth size and shape of the permanent incisor teeth have been studied and analyzed about the mean size, S.D, S.E, etcs and percentage from stone model of 100 Korean male and 74 Korean female. The results were as follows. 1. The crown length of permanent incisor teeth were longer in males than in females statistical differences of males and female were not found. 2. the mesio-distal diameters of permanent incisor teeth were larger in males than in females and statistical differences of males and females were found in mandibular lateral incisor and the bigest were max. central incisor, 2nd max. lateral incisor, 3rd man. lateral incisor and the smallest were man. central incisor. 3. The square form in max. central incisor was the greatest percentage and the tapering form in max. lateral incisor and man, incisor was the greatest percentage but tapering form and ovoid form and other shape were found in max. lateral at the same ratio. 4. Concerning the labial developmental groove "midium" was the greatest percentage in the max. central incisor and "low" was the greatest percentage in the man incisor. Concerning the incisal line, straight line was the greatest percentage in the max, incisor and man, incisor and concerning the lingual tubercle "none" was the greatest percentage in the max. incisor. 5. In comparison between left side and right side of incisor, the ratio of same shape ware 22.4%-36.2% but similar or dissimilar cases were more frequently found.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.3
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• pp.388-402
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• 2000

The radiation characteristics of leaky antenna from the dielectric-coated conducting cylinder with periodic corrugation are investigated theoretically for the infinite and finite periodic structures. For the infinite periodic structure, mode-matching method is applied. The integral equation is derived for the finite periodic structure by use of the Fourier transform and mode expansion and a simultaneous linear equation is obtained. The influences of the corrugation slot width, corrugation depth, dielectric thickness, cylinder radius, and finite corrugation number on the radiation characteristics (leakage constant, phase constant, and radiation pattern) are investigated. The results of the finite periodic corrugations are compared with those of the infinite extent structure and good agreement is found. To reduce high side lobe levels of the uniform finite periodic structure, tapering process on the beginning and end section of antenna and nonuniform quasi-period slot arrays are considered. Especially, for the corrugation period, width and depth used for a corrugated surface wave antenna, through the proper tapering process, end-fire radiation pattern with reduced side lobe levels is given.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.579-588
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• 2007

Statement of problem: A tenderness of the dentin after tapering of teeth for dental prosthesis is a common phenomenon. In practice, the alternative desensitizer may be used for minor pain after tapering of teeth. Purpose: In this study, the desensitizers were used to investigate the affect decreasing of shear bond strength according to the use of various cement, such as resin, Glass Ionomer, and phosphate cement. Material and method: Three different desensitizers were used on this study Compositions of two dentin desensitizers were HEMA(hydroxyethylmethacrylate) and glutaraldehyde. The other one is oxalic acid. Three dentin desensitizers applied on 12 degrees taper teeth. Then, Ni-Cr crowns were bonded with Resin cement, Zinc Phosphate (ZPC) cement and Glass Ionomer (GIC) cement. 120 human premolar teeth were used for specimens. The specimens were divided into four group as the reference and the empirical each with thirty specimens, then further divided into 12 group according to type of desensitizers and cement types. The shear bond strength were measured by Instron multi task instrument. Results: According to the result, the measured shear bond strength in order from the weakest to the strongest in general was ZPC, Resin, and GIC. And it is found that the application of desensitizers on dentin surface does not affect the shear bond strength. Conclusion: Dentin desensitizers that alleviate or prevent a dentin tenderness, usually contains HEMA and glutaraldehyde compounds. Such desensitizers are widely used in clinical studies. By applying the dentin desensitizer on the exposed dentin surface, the dentin capillary are blocked and periodontal membrane and cementum can not be drawn in pulp cavity. Since HEMA and glutaraldehyde may cause harm to the pulp cavity, an alternative desensitizer was developed.

• Journal of the Optical Society of Korea
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• v.8 no.2
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• pp.90-95
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• 2004

The structure of Ti:LiNbO$_3$optical waveguide with a mode size far different from that of single mode optical fiber has been optimized by tapering the waveguide ends. This work was focused on determining the optimized sets of parameters for the fabrication of low-loss Ti indiffused optical waveguides in LiNbO$_3$. Numerical and analytical modeling were applied to simulate the guiding quality and to determine the mode sizes. Based on these modeling results, new waveguide structures with tapered ends have been defined, fabricated and characterized in the respect of the coupling of fiber to Ti-indiffused LiNbO$_3$waveguide.

• Structural Engineering and Mechanics
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• v.60 no.3
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• pp.365-386
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• 2016

This paper describes a systematic numerical investigation into the nonlinear elastic behavior of conical shells, with various types of initial imperfections, subject to a uniformly distributed axial compression. Three different patterns of imperfections, including first axisymmetric linear bifurcation mode, first non-axisymmetric linear bifurcation mode, and weld depression are studied using geometrically nonlinear finite element analysis. Effects of each imperfection shape and tapering angle on imperfection sensitivity curves are investigated and the lower bound curve is determined. Finally, an empirical lower bound relation is proposed for hand calculation in the buckling design of conical shells.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2162-2171
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• 1993

Geneal Structure optimization is utilized to minimize the weight of structures while satisfying constraints imposed on stress, displacements and natural frequencies, etc. Sandwich structures consist of inside core and outside face sheets. The selected sandwich structures are isotropic sandwich beams and isotropic sandwich plate. The face sheets are treated as membrane and assumed to carry only tensions, while the core is assumed to carry only transverse shear. The characteristic of the varying area are considered by adding the projected component of the tension to the transverse shear. The bending theory and energy method are adopted for analyzing sandwich beams and plates, respectively. In the optimization process, the cost function is the weight of a structure, and a deflection and stress constraints are considered. Design variable are thickness and tapering coefficients which determine the shape of a structure. An existing optimization code is used for solving the formulated problems.