• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.470-472
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• 1987

This paper deals with the continuous-discrete estimation problem using FIR filters and performs modeling error analyses of the FIR filters, compared to Kalman filter and the limited memory filters, via computer simulations. It is shown that, the less driving noise the system has, the better performance the FIR filter exhibits and that this characteristic appears rare distinctly in nonlinear system than in linear systems.

• Earthquakes and Structures
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• 제10권2호
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• pp.409-428
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• 2016

To realise the full benefits of a self-centering seismic resilient system, the designer must ensure that the entire structure does indeed re-center following an earthquake. The idealised flag-shaped hysteresis response that is often used to define the cyclic behaviour of self-centering concrete systems seldom exists and the residual drift of a building subjected to an earthquake is dependent on the realistic cyclic hysteresis response as well as the dynamic loading history. Current methods that are used to ensure that re-centering is achieved during the design of self-centering concrete systems are presented, and a series of cyclic analyses are used to demonstrate the flaws in these current procedures, even when idealised hysteresis models were used. Furthermore, results are presented for 350 time-history analyses that were performed to investigate the expected residual drift of an example self-centering concrete wall system during an earthquake. Based upon the results of these time-history analyses it was concluded that due to dynamic shake-down the residual drifts at the conclusion of the ground motion were significantly less than the maximum possible residual drifts that were observed from the cyclic hysteresis response, and were below acceptable residual drift performance limits established for seismic resilient structures. To estimate the effect of the dynamic shakedown, a residual drift ratio was defined that can be implemented during the design process to ensure that residual drift performance targets are achieved for self-centering concrete wall systems.

• 한국지진공학회논문집
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• 제20권7_spc호
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• pp.473-483
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• 2016

In this paper, seismic performance assessment has been examined for a mid-rise RC building subjected to 2016 Gyeongju earthquake occurred in Korea. For the purpose of the paper, 2D external and internal frames in each direction of the building have been employed in the present comparative analyses. Nonlinear static pushover analyses have been conducted to estimate frame capacities. Nonlinear dynamic time-history analyses have also been carried out to examine demands for the frames subjected to ground motions recorded at stations in near of Gyeongju and a previous earthquake ground motion. Analytical predictions demonstrate that maximum demands are significantly affected by characteristics of both spectral acceleration response and spectrum intensity over a wide range of periods. Further damage potential of the frames has been evaluated in terms of fragility analyses using the same ground motions. Fragility results reveal that the ground motion characteristics of the Gyeongju earthquake have little influence on the seismic demand and fragility of frames.

• 한국지진공학회논문집
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• 제21권6호
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• pp.311-322
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• 2017

In this study, the seismic performance of concrete-steel composite moment frame structures equipped with seismic retrofitting systems such as seismic reinforcement, base isolators, and bracing members, which are typical earthquake damage mitigation systems, is evaluated through nonlinear dynamic analyses. A total of five frame models were designed and each frame model was developed for numerical analyses. A total of 80 ground acceleration data were used to perform the nonlinear dynamic analysis to measure ground shear force and roof displacement, and to evaluate the behavioral performance of each frame model by measuring inter-story drift ratios. The analysis results indicate that the retrofitting device of the base isolator make a significant contribution to generating relatively larger absolute displacement than other devices due to flexibility provided to interface between ground and column base. However, the occurrence of the inter-story drift ratio, which is a relative displacement that can detect the damage of the structure, is relatively small compared with other models. On the other hand, the seismic reinforced frame model enhanced with the steel plate at the lower part of the column was found to be the least efficient.

• Steel and Composite Structures
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• 제12권3호
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• pp.231-248
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• 2012

This research aims to investigate the structural behavior of concentrically braced frames after element loss by performing nonlinear static and dynamic analyses such as Time History Analysis (THA), Pushdown Analysis (PDA), Vertical Incremental Dynamic Analyses (VIDA) and Performance-Based Analysis (PBA). Such analyses are to assess the potential and capacity of this structural system for occurrence of progressive collapse. Besides, by determining the Failure Overload Factors (FOFs) and associated failure modes, it is possible to relate the results of various types of analysis in order to save the analysis time and effort. Analysis results showed that while VIDA and PBA according to FEMA 356 are mostly similar in detecting failure mode and FOFs, the Pushdown Overload Factors (PDOFs) differ from others at most to the rate of 23%. Furthermore, by sensitivity analysis it was observed that among the investigated structures, the eight-story frame had the most FOF. Finally, in this research the trend of FOF and the FOF to critical member capacity ratio for the plane split-X braced frames were introduced as a function of the number of frame stories.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1134-1145
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• 2021

A design parameter study is presented for the closed-loop type passive containment cooling system (PCCS) which is equipped with two heat exchangers: one installed at the inside of the containment and the other submerged in the water pool at the outside of the containment. A GOTHIC code model for PCCS performance analyses was set up and the design parameters such as the heat exchanger sizes, locations, and water pool tank volumes were analyzed to investigate the feasibility of installing this type of PCCS in PWRs like OPR-1000 being operated in Korea. We identified the size of the circulation loop and heat exchangers as major design parameters affecting the performance of PCCS. The analyses showed that the heat exchangers in the inside of the containment would be more influential on the heat removal capability of PCCS than that installed in the water pool at the outside of the containment. Hence, it was recommended to down-size the heat exchangers in the water pool to optimize PCCS without compromising its performance. Based on the parametric study, it was demonstrated that a closed-loop type PCCS could be designed sufficiently compact for installation in the available space within the containment of PWRs like OPR-1000.

• 한국건설관리학회논문집
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• 제8권2호
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• pp.75-83
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• 2007

최근 국내의 설계시공일괄방식(이하, 일괄방식)은 설계시공분리방식(이하, 기타방식)에 비해 높은 초기투자비용으로 인하여, 효용성에 대한 의문이 지속되고 있다 한편 발주방식별 성능을 평가한 기존의 연구를 살펴보면, 일괄방식은 공기측면과 품질측면에서 기타방식에 비해 우수한 것으로 보고되고 있다. 비교적 정량적 평가가 가능한 공기측면의 성과와 달리, 품질 측면의 성능은 해당 시설물의 발주자와의 면담을 통하여 만족도 수준을 평가하는 정성적인 평가가 대부분이다. 따라서 이 연구에서는 기존의 연구와는 달리, 2000년 이후 일괄방식과 기타방식으로 발주된 교량계획에 대한 성능수준을 평가하기 위하여, 설계도서 중심으로 계획성, 시공성, 유지관리성 등의 측면에서 평가해 보고자 한다. 이를 통하여 실제로 발주방식별 품질 등의 성능 측면에서 발주방식별 성능수준의 차이를 도출하였다.

• Structural Engineering and Mechanics
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• 제77권2호
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• pp.197-215
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• 2021

Under a severe environment of multiple hazards such as earthquakes and winds, the life-cycle performance of engineering structures may inevitably be deteriorated due to the fatigue effect caused by long-term exposure to wind loads, which would further increase the structural vulnerability to earthquakes. This paper presents a framework for evaluating the lifetime structural seismic performance under the effect of wind-induced fatigue considering different sources of uncertainties. The seismic behavior of a high-rise steel-concrete composite frame with buckling-restrained braces (FBRB) during its service life is systematically investigated using the proposed approach. Recorded field data for the wind hazard of Fuzhou, Fujian Province of China from Jan. 1, 1980 to Mar. 31, 2019 is collected, based on which the distribution of wind velocity is constructed by the Gumbel model after comparisons. The OpenSees platform is employed to establish the numerical model of the FBRB and conduct subsequent numerical computations. Allowed for the uncertainties caused by the wind generation and structural modeling, the final annual fatigue damage takes the average of 50 groups of simulations. The lifetime structural performance assessments, including static pushover analyses, nonlinear dynamic time history analyses and fragility analyses, are conducted on the time-dependent finite element (FE) models which are modified in lines with the material deterioration models. The results indicate that the structural performance tends to degrade over time under the effect of fatigue, while the influencing degree of fatigue varies with the duration time of fatigue process and seismic intensity. The impact of wind-induced fatigue on structural responses and fragilities are explicitly quantified and discussed in details.

• 보건의료산업학회지
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• 제11권1호
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• pp.43-53
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• 2017

Objectives : In this paper, we proposed a method to comprehensively examine the roles of medical insurance review nurses' by analyses of task importance and task performance. Methods : For the analyses, we used the responsesof 268 nurses who completed a questionnaire for members of the Medical Insurance Review Nurses Association in 2015, and analyzed task importance and task performance using the IPA method and the standard task guide. Results : There were significant differences in task importance and task performance according to task position. In the category of 'Keep up the good work,' 'Calculate benefit standard' was indicated only in administrative positions, and in the category of 'Concentrate here,' 'Manage hospital resources' and 'Process after appeal results' was demonstrated only in general positions. There were differences in the 'Low priority' and 'Possible overkill' categories by task performance according to task position. Conclusions : Our results indicate the necessity of a new education system and task reassignment according to task importance and task performance as perceived by medical insurance review nurses.

• Computers and Concrete
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• 제15권6호
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• pp.921-933
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• 2015

The aim of this study is to determine the earthquake performances of reinforced concrete (R/C) residential buildings in Turkey and to analyze the parameters that affect the performance. The performance of Turkish residential buildings, determined by their levels of damage, directly relates to their structural systems. Damage parameters observed from previous earthquakes define structural parameters selected to be used in the present study. Five different types of frame R/C buildings were modeled. For the analysis, the model buildings vary according to the number of stories, column sizes, and reinforcement and concrete strength parameters. The analyses consider gravity forces and earthquake loads through 1975 and 2007 Turkish design codes. In a total of 720 different R/C buildings were investigated for the analysis to obtain capacity curves. A performance evaluation was employed by considering the Turkish design code (TDC-2007). The current study ignores irregularities such as soft stories or short columns. The study's analysis considers a comparison of the parameters' influence on the structural performance of the model buildings.