• Title, Summary, Keyword: modification factor

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Case-based Software Project Network Generation by the Least Modification Principle (사례의 수정최소화 기법에 의한 소프트웨어 프로젝트 네트워크 생성시스템)

  • Lee, No-Bok;Lee, Jae-Kyu
    • Asia pacific journal of information systems
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    • v.13 no.1
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    • pp.103-118
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    • 2003
  • Software project planning is usually represented by a project activity network that is composed of stages of tasks to be done and precedence restrictions among them. The project network is very complex and its construction requires a vast amount of field knowledge and experience. So this study proposes a case-based reasoning approach that can generate the project network automatically based on the past cases and modification knowledge. For the case indexing, we have adopted 17 factors, each with a few alternative values. A special structure of this problem is that the modification effort can be identified by each factor independently. Thus it is manageable to identify 85 primitive modification actions(add and delete activities) and estimate its modification efforts in advance. A specific case requires a combination of primitive modifications. Based on the modification effort knowledge, we have adopted the Least Modification approach as a metric of similarity between a new project and past cases. Using the Least Modification approach and modification knowledge base, we can automatically generate the project network. To validate the performance of Least Modification approach, we have compared its performance with an ordinary minimal distance approach for 21 test cases. The experiment showed that the Least Modification approach could reduce the modification effort significantly.

A Study on the Response Modification Factor for a 5-Story Reinforced Concrete IMRF (5층 철근콘크리트 중간모멘트골조의 반응수정계수에 관한 연구)

  • Kang, Suk-Bong;Lim, Byeong-Jin
    • Journal of the Earthquake Engineering Society of Korea
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    • v.16 no.5
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    • pp.13-21
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    • 2012
  • In this study, the response modification factor for a RC IMRF is evaluated via pushover analysis, where 5-story structures were designed in accordance with KBC2009. The bending moment-curvature relationship for beams and columns was identified with a fiber model, and the bending moment-rotation relationship for beam-column joints was calculated using a simple and unified joint shear behavior model and the moment equilibrium relationship for the joint. The results of the pushover analysis showed that the strength of the structure was overestimated with negligence of the inelastic shear behavior of the beam-column joint, and that the average response modification factor for category C was 7.78 and the factor for category D was 3.64.

Seismic response modification factors for stiffness degrading soil-structure systems

  • Ganjavi, Behnoud;Bararnia, Majid;Hajirasouliha, Iman
    • Structural Engineering and Mechanics
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    • v.68 no.2
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    • pp.159-170
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    • 2018
  • This paper aims to develop response modification factors for stiffness degrading structures by incorporating soil-structure interaction effects. A comprehensive parametric study is conducted to investigate the effects of key SSI parameters, natural period of vibration, ductility demand and hysteretic behavior on the response modification factor of soil-structure systems. The nonlinear dynamic response of 6300 soil-structure systems are studied under two ensembles of accelograms including 20 recorded and 7 synthetic ground motions. It is concluded that neglecting the stiffness degradation of structures can results in up to 22% underestimation of inelastic strength demands in soil-structure systems, leading to an unexpected high level of ductility demand in the structures located on soft soil. Nonlinear regression analyses are then performed to derive a simplified expression for estimating ductility-dependent response modification factors for stiffness degrading soil-structure systems. The adequacy of the proposed expression is investigated through sensitivity analyses on nonlinear soil-structure systems under seven synthetic spectrum compatible earthquake ground motions. A good agreement is observed between the results of the predicted and the target ductility demands, demonstrating the adequacy of the expression proposed in this study to estimate the inelastic demands of SSI systems with stiffness degrading structures. It is observed that the maximum differences between the target and average target ductility demands was 15%, which is considered acceptable for practical design purposes.

Evaluation of the Response Modification Factor for RC Wall-type Structures (철근콘크리트 벽식 구조물의 반응수정계수 평가에 관한 연구)

  • 한상환;이리형;오영훈;천영수
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.433-438
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    • 1998
  • Design lateral strength calculated by current seismic design code is prescribed to be much lower than the force level required for a structure to respond elastically during design level earthquake ground motion. Present procedures for calculating seismic design forces are based on the use of elastic spectra reduced by a strength reduction factor known as "response modification factor, R". This factor accounts for the inherent ductility, overstrength, redundancy, and damping of a structural system. This study considers ductility and overstrength of the wall-type structure for investigating R factor. This means that R factor is determined from the product of "ductility-based R factor($R_$\mu$$) and overstrength factor($R_s$). $R_$\mu$$ factor is calibrated to attain the targer ductility ratio (system ductility capacity) and produced in the from of $R_$\mu$$ spectra considering the influence of target ductility, natural period, and hysteretic model. On the other hand, $R_s$ is more difficult to quantify, since it depends on both material and system-dependent uncertain parameters. In this study Rs factor was determined from the result of push-over analysis.-over analysis.

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Current Situation and Modification of Kitchen Space by Elderly-headed Household (노인단독가구의 부엌공간 실태와 개조에 관한 연구)

  • Kwon, Oh-Jung;Kim, Mi-Hee;Ha, Hae-Wha
    • Proceeding of Spring/Autumn Annual Conference of KHA
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    • pp.144-148
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    • 2006
  • Kitchen space is one of the most dangerous places for the elderly. Modification of kitchen space for improving safety and independence for older residents is very important factor for aging -in-place. The purpose of this study wes to identify the current situation and modification of kitchen space by elderly-headed household. The sample included 108 respondents over the age 65 who consisted of elderly-couple or single person household with homeownership in Seoul. The data were analyzed by descriptive statistics. Based on the findings of the study, the present incidence and recognition of future need in kitchen modification were identified. Changes in kitchen space made tended to be nonstructural or relatively inexpensive items. In conclusion, this study suggests several ideas for improving current physical problems of kitchen space to support daily living of older residents.

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Evaluation of Seismic Performance Factors of Diagrid Structural System (다이아그리드 구조 시스템의 내진성능계수 평가)

  • Kim, Kyoung-Hwan;Ju, Young-Kyu;Kim, Sang-Dae
    • Journal of Korean Society of Steel Construction
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    • v.22 no.3
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    • pp.229-239
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    • 2010
  • As a new structural system, the diagrid system resists both gravity and lateral loads with diagonal columns. In current seismic design provisions, however, the response modification factor for a new structural system is not provided yet. ATC-63 provides a new methodology for defining various seismic performance factors, including the response modification factor. ATC-63 includes the collapse margin ratio in modifying the response modification factor, which can vary with many structural systems. In this paper, a non-linear static analysis and a dynamic analysis were conducted for four different diagrid models with 4-to 36-story heights. From these analyses, the response modification factor of the diagrid system was evaluated.

Structural Design of Basement Exterior Wall using Modification Factor (보정계수를 이용한 지하외벽의 구조설계)

  • Kim, Dong-Gun;Kim, Young-Chan
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.6 no.3
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    • pp.159-165
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    • 2002
  • Currently structural design of basement exterior wall is based on the assumption of boundary condition of plate, which may lead to erroneous results. In this study, the behavior of basement exterior wall subject to earth pressure and hydraulic pressure is investigated using linear finite element analysis. Parametric studies are conducted to investigate the variation of moment and shear force according to column-to-wall stiffness and aspect ratios. Using these numerical results, modification factors applicable to the design of basement exterior wall are presented. Design example is illustrated, showing satisfactory results.

Structural Dynamics Modification Using Surface Grooving Technique (임의의 형태를 갖는 흠을 이용한 표면형상변형을 통한 동특성 변경)

  • 박미유;박영진;박윤식
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.859-863
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    • 2004
  • Structural Dynamics Modification is very effective technique to improve structure's dynamic characteristics by adding or removing auxiliary structures, changing material property, changing shape of structure. In this research, using the surface grooving technique, shape of base structure was changed to improve its first natural frequency. Utilizing the result of sensitivity analysis, groove shape was formed gathering the many small embossing elements. For this process, Sensitivity Criterion Factor was introduced. To reduce its amount of calculation, the range of target area was restricted to their neighboring area and that result was very successful.

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Structural Dynamics Modification Using Surface Grooving Technique : Application to the HDD Cover model (그루브를 이용한 표면형상변형 동특성 변경법 :HDD 커버에 대한 적용)

  • Park, Mi-You;Park, Young-Jin;Park, Youn-Sik
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.826-829
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    • 2004
  • Structural Dynamics Modification is very effective technique to improve structure's dynamic characteristics by adding or removing auxiliary structures, changing material property, changing shape of structure. In this research, using the surface grooving technique, shape of base structure was changed to improve its first natural frequency. Utilizing the result of frequency variation analysis, groove shape was formed gathering the many small embossing elements. For this process, Criterion Factor was introduced. To reduce its amount of calculation, the range of target area was restricted to their neighboring area and initial grooving point was selected using high-strain energy. This surface grooving technique was successfully applied to the HDD cover model.

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Estimation of floor response spectra induced by artificial and real earthquake ground motions

  • Pu, Wuchuan;Xu, Xi
    • Structural Engineering and Mechanics
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    • v.71 no.4
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    • pp.377-390
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    • 2019
  • A method for estimating the floor response spectra (FRS) of elastic structures under earthquake excitations is proposed. The method is established based on a previously proposed direct estimation method for single degree of freedom systems, which generally overestimates the FRS of a structure, particularly in the resonance period range. A modification factor is introduced to modify the original method; the modification factor is expressed as a function of the period ratio and is determined through regression analysis on time history analysis results. Both real and artificial ground motions are considered in the analysis, and it is found that the modification factors obtained from the real and artificial ground motions are significantly different. This suggests that the effect of ground motion should be considered in the estimation of FRS. The modified FRS estimation method is further applied to a 10-story building structure, and it is verified that the proposed method can lead to a good estimation of FRS of multi-story buildings.