• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.107-112
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• 2005

Recently proposed stable teleoperation control scheme, base on time domain passivity, is modified to remove several conservatisms. During unconstrained motion and contacting with soft and deformable environments, the two-port time domain passivity approach [21] was excessively dissipating energy even though it was stable without any energy dissipation. The main reason of this conservatism is on the fact that the time domain passivity controller does not include the external energy dissipation elements at the slave manipulator. The measured interaction force between slave and environment allow the time domain passivity observer to include the amount of energy dissipation of the slave manipulator to the monitored energy. With the modified passivity observer, reference energy following idea [24] is applied to satisfy the passivity condition. The feasibility of the developed methods is proved with experiments. Improved performance is obtained in unconstrained motion and contacting with a soft environment.

• Steel and Composite Structures
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• v.5 no.5
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• pp.345-358
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• 2005

The response of single story buildings and other case studies are investigated to observe trends in response and to develop a better understanding of the impact of some design parameters on the seismic response of CBF. While it is recognized that many parameters have an influence on the behavior of braced frames, the focus of this study is mostly on quantifying energy dissipation in compression and its effectiveness on seismic performance. Based on dynamic analyses of single story braced frame and case studies, it is found that a bracing member designed with bigger R and larger KL/r results in lower normalized cumulative energy, i.e., cumulative compressive energy normalized by the corresponding tensile energy (${\sum}E_C/E_T$), in both cases.

• Structural Engineering and Mechanics
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• v.64 no.3
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• pp.301-310
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• 2017

For further development of passive control systems to dissipate larger seismic energy and prevent the structures from earthquake losses, this paper proposes an innovative two-level control system to improve behavior of chevron braced steel frames. Combining two Knee Braces, KB, and a Vertical Link Beam, VLB, in a chevron braced frame, this system can reliably sustain main shock and aftershocks in steel structures. The performance of this two-level system is examined through a finite element analysis and quasi-static cyclic loading test. The cyclic performances of VLB and KBs alone in chevron braced frames are compared with that of the presented two-level control system. The results show appropriate performance of the proposed system in terms of ductility and energy dissipation in two different excitation levels. The maximum load capacity of the presented system is about 30% and 17% higher than those of the chevron braced frames with KB and VLB alone, respectively. In addition, the maximum energy dissipation of the proposed system is about 78% and 150% higher than those of chevron braced frames with VLB and KB respectively under two separate levels of lateral forces caused by different probable seismic excitations. Finally, high performance under different earthquake levels with competitive cost and quick installation work for the control system can be found as main advantages of the presented system.

• Earthquakes and Structures
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• v.12 no.2
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• pp.201-211
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• 2017

This paper experimentally investigates the effect of yield strength of reinforcing bars and stirrups on the seismic performance of reinforced concrete (RC) circular piers. Reversed cyclic loading tests of nine-large scale specimens with longitudinal and transverse reinforcement of different yield strengths (varying between HRB335, HRB500E and HRB600 rebars) were conducted. The test parameters include the yield strength and amount of longitudinal and transverse reinforcement. The results indicate that the adoption of high-strength steel (HSS) reinforcement HRB500E and HRB600 (to replace HRB335) as longitudinal bars without reducing the steel area (i.e., equal volume replacement) is found to increase the moment resistance (as expected) and the total deformation capacity while reducing the residual displacement, ductility and energy dissipation capacity to some extent. Higher strength stirrups enhance the ductility and energy dissipation capacity of RC bridge piers. While the product of steel yield strength and reinforcement ratio ($f_y{\rho}_s$) is kept constant (i.e., equal strength replacement), the piers with higher yield strength longitudinal bars are found to achieve as good seismic performance as when lower strength bars are used. When higher yield strength transverse reinforcement is to be used to maintain equal strength, reducing bar diameter is found to be a better approach than increasing the tie spacing.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.6
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• pp.65-72
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• 2002

This study estimates steel house shear wall's seismic performance depending on trend of seismic design. As a result at cyclic-test, the capability of energy dissipation about X1SPCH during this test is good enough. The capability of energy dissipation of X3SPCH and X4SPCH was better than that of X1SPCH. The X2SPCH which is similar to real X-braced shear wall has better seismic performance than shear wall braced with structural sheathing materials on pseudo-dynamic test.

• Earthquakes and Structures
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• v.19 no.5
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• pp.361-377
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• 2020

In the present research work, the effectiveness and the efficiency of a retrofitting approach using a layer of ultra-high performance fiber reinforced concrete (UHPFRC) jacket for damaged substandard exterior beam-column joints (BCJs) is experimentally investigated. The main objective of this study is to rehabilitate the already damaged BCJs to meet the serviceability requirements without compromising safety. According to the proposed strengthening technique, a chipped surface, lightly brushed with a dry condition was selected for making a successful bond between normal concrete substrate surface (NCSS) and UHPFRC. Then a fresh UHPFRC jacket with a thickness of 30 mm was cast around the damaged specimens. The entire test matrix was comprised of three 1/3 scale damaged exterior BCJs with a different column axial load (CAL). These specimens were repaired with UHPFRC and retested under monotonic loading. Based on the experimental results, repaired specimens showed an excellent performance in terms of their load-displacement response, maximum strength, displacement ductility, initial stiffness, secant stiffness and energy dissipation capacity when compared with the corresponding values registered when these specimens were tested in their virgin state. This rehabilitative intervention not only restored the strength, stiffness, ductility and energy dissipation capacity of severely damaged specimens but also improved their performance.

• Earthquakes and Structures
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• v.18 no.2
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• pp.185-199
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• 2020

A computationally-efficient method for multi-criteria optimisation is developed for performance-based seismic design of friction energy dissipation dampers in RC structures. The proposed method is based on the concept of Uniform Distribution of Deformation (UDD), where the slip-load distribution along the height of the structure is gradually modified to satisfy multiple performance targets while minimising the additional loads imposed on existing structural elements and foundation. The efficiency of the method is demonstrated through optimisation of 3, 5, 10, 15 and 20-storey RC frames with friction wall dampers subjected to design representative earthquakes using single and multi-criteria optimisation scenarios. The optimum design solutions are obtained in only a few steps, while they are shown to be independent of the selected initial slip loads and convergence factor. Optimum frames satisfy all predefined design targets and exhibit up to 48% lower imposed loads compared to designs using a previously proposed slip-load distribution. It is also shown that dampers designed with optimum slip load patterns based on a set of spectrum-compatible synthetic earthquakes, on average, provide acceptable design solutions under multiple natural seismic excitations representing the design spectrum.

• Steel and Composite Structures
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• v.34 no.6
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• pp.891-907
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• 2020

Many studies reveal that during destructive earthquakes, most of the structures enter the inelastic phase. The amount of hysteretic energy in a structure is considered as an important criterion in structure design and an important indicator for the degree of its damage or vulnerability. The hysteretic energy value wasted after the structure yields is the most important component of the energy equation that affects the structures system damage thereof. Controlling this value of energy leads to controlling the structure behavior. Here, for the first time, the hysteretic behavior and energy dissipation capacity are assessed at presence of elliptical braced resisting frames (ELBRFs), through an experimental study and numerical analysis of FEM. The ELBRFs are of lateral load systems, when located in the middle bay of the frame and connected properly to the beams and columns, in addition to improving the structural behavior, do not have the problem of architectural space in the bracing systems. The energy dissipation capacity is assessed in four frames of small single-story single-bay ELBRFs at ½ scale with different accessories, and compared with SMRF and X-bracing systems. The frames are analyzed through a nonlinear FEM and a quasi-static cyclic loading. The performance features here consist of hysteresis behavior, plasticity factor, energy dissipation, resistance and stiffness variation, shear strength and Von-Mises stress distribution. The test results indicate that the good behavior of the elliptical bracing resisting frame improves strength, stiffness, ductility and dissipated energy capacity in a significant manner.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.113-114
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• 2022

The purpose of this study is to identify the rear energy transfer amount and time delay capability of the protection panel that has been impated by a projectile and the protection panel reinforced the foam polypropylene on the rear of the fiber reinforced cement itious composites, and compared and analyzed the load resistance capacity, energy dissipation capacity, and impact delay capacity when dynamic extreme load were applied to the specimen.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.105-110
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• 2020

The global battery market is rapidly growing due to the development of vehicles(EV) and wireless electronic products. In particular logistics robots, which hielp to produce EVs, have attracted much interest in research in Korea Because logistics sites and factories operate continuously for 24 hours, the technology that can dramatically increase the operation time of the logistics equipment is rapidly developing, and various high-level technologies are required for the batteries used in. for example, logistics robots. These required technologies include those that enable rapid battery charging as well wireless charging to charge batteries while moving. The development of these technologies, however, result in increasing explosions and topical accidents involving rapid charging batteries These accidents due to the thermal shock caused by the heat generated during the charging of the battery cell. In this study, a performance evaluation of a heat dissipation design using infrared thermal imaging was performed on an energy storage systrm(Ess) applied with an internal heat conduction cooling method using a heating plate.