• 대한음성학회지:말소리
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• 제59호
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• pp.69-87
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• 2006

Among the conventional time-scale modification (TSM) methods, the synchronized overlap and add (SOLA) method is widely used due to its good performance relative to computational complexity But the SOLA method remains complex due to its synchronization procedure using the normalized cross-correlation function. In this paper, we introduce a computationally efficient SOLA method utilizing 3 level center clipping method, as well as zero-crossing and level-crossing information. The result of subjective preference test indicates that the proposed method can reduce the computational complexity by over 80% compared with the conventional SOLA method without serious degradation of synthesized speech quality.

• Structural Engineering and Mechanics
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• 제63권1호
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• pp.23-35
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• 2017

A nonlinear static procedure considering work-energy principle and global failure mechanism to estimate base shears of reinforced concrete (RC) frame-type structures is presented. The relative energy equation comprising of elastic vibrational energy, plastic strain energy and seismic input energy is obtained. The input energy is modified with a factor depending on damping ratio and ductility, and the energy that contributes to damage is obtained. The plastic energy is decreased with a factor to consider the reduced hysteretic behavior of RC members. Given the pre-selected failure mechanism, the modified energy balance equality is written using various approximations for modification factors of input energy and plastic energy in scientific literature. External work done by the design lateral forces distributed to story levels in accordance with Turkish Seismic Design Code is calculated considering the target plastic drift. Equating the plastic energy obtained from energy balance to external work done by the equivalent inertia forces considering, a total of 16 energy-based base shears for each frame are derived considering different combinations of modification factors. Ductility related parameters of modification factors are determined from pushover analysis. Relative input energy of multi degree of freedom (MDOF) system is approximated by using the modal-energy-decomposition approach. Energy-based design base shears are compared with those obtained from nonlinear time history (NLTH) analysis using recorded accelerograms. It is found that some of the energy-based base shears are in reasonable agreement with the mean base shear obtained from NLTH analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.311.1-311
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• 2002

To reduce the vibration of a gear driving system, the modification of gear tooth from the orignal involute gear profile is usually done in gear manufacturers. The quantity of the tooth modification has been decided on the basis of the intereference between two gear teeth during gear meshing and the elastic deformation due to loading. (omitted)

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.25-30
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• 2002

To reduce the vibration of a gear driving system, the modification of gear tooth from the orignal involute gear profile is usually done in gear manufacturers. The quantity of tooth modification has been decided on the basis of the interference between two gear teeth during gear meshing and the elastic deformation due to loading. However, the dynamic characteristics with tooth modification has to be investigated to avoid the instability to the variation of gear meshing stiffness and the nonlinearity due to gear backlash which results in sub- or super-harmonics in its responses. This research shows the dynamic characteristics with various tooth modifications in its type and quantity.

• 한국소음진동공학회논문집
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• 제13권9호
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• pp.688-693
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• 2003

To reduce the vibration of a gear driving system. the modification of gear tooth from the orignal involute gear profile is usually done in gear manufacturers. The quantity of tooth modification has been decided on the basis of the interference between two gear teeth during gear meshing and the elastic deformation due to loading. However. the dynamic characteristics with tooth modification has to be investigated to avoid the instability to the variation of gear meshing stiffness and the nonlinearity due to gear backlash which results in sub- or super-harmonics in its responses. This research shows the dynamic characteristics with various tooth modifications in its type and quantity.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.228-235
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• 2002

As the response spectrum method generally used in the earthquake resistant design is a linear method, the nonlinear behavior of a structure is to be reflected with a specific factor. Such factors are provided in the "Design Criteria for Roadwaybridges"as response modification factors and in the Eurocode 8, Part 2 as behavior factors. In this study a 5-span steel box bridge with single column piers is selected and the behavior factor is determined. The linear time history analyses are carried out with a simple linear model, where the nonlinear behavior of piers leading to the ductile failure mechanism is considered as predetermined characteristic curves.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 봄 학술발표회 논문집
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• pp.25-32
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• 1998

Most recent seismic design codes include Response Modification Factor(RMF) for determining equivalent lateral forces. The RMF is used to reduce the linear elastic design spectrum to account for the energy dissipation capacity, overstrength and damping of the structure. In this study the RMF is defined as the ratio of the absolute maximum linear elastic base shear to the absolute maximum nonlinear base shear of a structure subject to the same earthquake accelerogram. This study investigates the effect of hysteretic model, as well as target ductility ratio and natural period on duct based RMF using nonlinear dynamic analyses of the SDOF systems. Special emphasis is given to the effects of the hysteretic characteristics such as strength deterioration and stiffness degradation. Results indicate that RMFs are dependent on ductility, period and hysteretic model.

• 대한조선학회논문집
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• 제44권5호
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• pp.542-550
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• 2007

A geometry modification is one of main keys in achieving a successful optimization. The optimized hull form generated from the geometry modification should be a realistic, faired form from the ship manufacturing point of view. This paper presents a practical hull optimization procedure using a parametric modification function. In the parametric modification function method, the initial ship geometry was easily deformed according to the variations of design parameters. For example, bulbous bow can be modified with several parameters such as bulb area, bulb length, bulb height etc. Design parameters are considered as design variables to modify hull form, which can reduce the number of design variables in optimization process and hence reduce its time cost. To verify the use of the parametric modification function, optimization for KCS was performed at its design speed (FN=0.26) and the wave making resistance is calculated using a well proven potential code with fully nonlinear free surface conditions. The design variables used are key design parameters such as Cp curve, section shape and bulb shape. This study shows that the hull form optimized by the parametric modification function brings 7.6% reduction in wave making resistance. In addition, for verification and comparison purpose, a direct geometry variation method using a bell-shape modification function is used. It is shown that the optimal hull form generated by the bell-shaped modification function is very similar to that produced by the parametric modification function. However, the total running time of the parametric optimization is six times shorter than that of the bell shape modification method, showing the effectiveness and practicalness from a designer point of view in ship yards.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.859-864
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• 2001

For earthquake resistance design, a response modification factor is used to reduce the design strength and it reflects ductility, reserve strength, redundancy and damping effect. But this factor has not theoretical basis. In this study, two response modification factors are compared and analyzed for shear wall apartment building.; the one is introduced by ATC-19 Procedures, the other is suggested FEMA-273 and ATC-40 through nonlinear static analysis. For the results, ATC-19 procedure gives a reasonable estimation to R factor. But $R_{u}$ by using FEAM-273 and ATC-40 methods is estimated so small in case of a minor or moderate earthquake region. Due to this fact, response modification factor is smaller than suggested load criterion 3.0. So, it needs to decrease wall volume and reduce the global strength and system stiffness for proper ductile behavior matching to domestic load criterion.

• Structural Engineering and Mechanics
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• 제69권6호
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• pp.591-605
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• 2019

Investigations on seismic performance of eccentrically braced frames equipped with dual vertical links have received little attention. Therefore, the main goal of this paper is to describe design steps for such frames and evaluate nonlinear performance of this system according to the reliability analysis. In this study, four and eight story frame structures are analyzed and the response modification factors for different intensity and damage levels are derived in a matrix form based on a new approach. According to the obtained results, the system has high ductility and acceptable seismic performance. Moreover, it is concluded that using response modification factor equal to 8 in the design of system provides desirable seismic reliability under the design and maximum probable hazard levels. Due to desirable performance and significant advantages of the dual vertical links, this system can be used as a main lateral load bearing system, in addition to its application for rehabilitation of damaged structures.