• Nuclear Engineering and Technology
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• v.31 no.6
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• pp.1-7
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• 1999

An innovative concept for a passive reactor shutdown system, so called self-actuated shutdown system(SASS), is inevitably required for the inherent safety in liquid metal reactor, which is designed with the totally different concept from the usual reactor shutdown system in LWR. SASS using Curie point electromagnet(CPEM) was selected as the passive reactor shutdown system for KALIMER (Korea Advanced Liquid MEtal Reactor). A mock-up of the SASS was designed, fabricated and tested. From the test it was confirmed that the mockup was self-actuated at the Curie point of the temperature sensing material used in the mockup. An articulated control rod was also fabricated and assembled with the CPEM to confirm that the control rod can be inserted into core even when the control rod guide tube is deformed due to earthquake. The operability of SASS in the actual sodium environment should be confirmed in the future. All the design and test data will be applied to the KALIMER design.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.307-310
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• 2005

The PCS system, which consists of precast concrete column and steel beam, has been under development. Experimental test has been carried out to investigate the structural performance of the system under earthquake. Two types of test specimens of beam-column joints are designed in order to compare the performances. One is the system with reinforced concrete slab and the other is without slab. It is found that the system with slab could satisfy all of the requirements from ACI Criteria such as strength, stiffness degradation and energy dissipation capacity except initial stiffness. It is also investigated that the stiffness of the joint is belong to rigid joint type according to Bjorhovde criterion. And it is observed that the partial-composite system between beam and slab is more effective than full-composite system in the respect of the energy dissipation capacity of the system.

• Journal of Korean Association for Spatial Structures
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• v.17 no.4
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• pp.35-42
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• 2017

This study develops a new hybrid passive energy dissipation device for seismic rehabilitation of an existing structure. The device is composed of a friction damper combined with a steel plate with vertical slits as a hysteretic damper. Analytical model is developed for the device, and the capacity of the hybrid device to satisfy a given target performance is determined based on the ASCE/SEI 7-10 process. The effect of the device is verified by nonlinear dynamic analyses using seven earthquake records. The analysis results show that the dissipated inelastic energy is concentrated on the hybrid damper and the maximum interstory drift of the SMRF with damping system satisfies the requirement of the current code.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.446-451
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• 2000

In case of strong earthquake, upper-sheat wall lowe-frame structures show the weak-story failure at lower part. Where we should guarantee sufficient strength, energy dissipation capacity and ductility. In this study, a typical structure was selected for a prototype and four 1:2.5 scaled models, representing the subassemblages including the interior column and the deep beam, were constructed. Experimental parameters include transverse reinforcement ratio and axial force. The non- linear behavior of the subassemblages subjected to the cyclic lateral displac-ement were evaluated through investigation of the ultimate strength, ductility, load-deformation characteristics. From the results of the tests on 4 specimens, it is concluded that the strength increased as the axial force increased and the ductility increased as the transverse reinforcement ratio increased.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.133-136
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• 2006

The mesoscale eddy field in the North Pacific Ocean, simulated by a high resolution eddy-resolving OGCM ($1/12^{\circ}C$ horizontal resolution), was analyzed, and compared with satellite altimetry data of TOPEX/Poseidon. High levels of eddy kinetic energy (EKE) appear near the Kurosho, North Equatorial Current (NEC), and Subtropical Countercurrent (STCC) in the western part of the subropical gyre. In particlure, it was found that the EKE level of the STCC has a well-defined annual cycle, but no distinct annual cycle of the EKE exists in any other zonal current of the North Pacific Ocean.

• Journal of Korean Association for Spatial Structures
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• v.15 no.4
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• pp.81-89
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• 2015

Damped outrigger systems have been proposed as a novel energy dissipation system to protect tall buildings from severe earthquakes and strong wind loads. In this study, semi-active damping devices such as magnetorheological (MR) dampers instead of passive dampers are installed vertically between the outrigger and perimeter columns to achieve large and adaptable energy dissipation. Control performance of semi-active outrigger damper system mainly depends on the control algorithm. Fuzzy logic control algorithm was used to generate command voltage sent to MR damper. Genetic algorithm was used to optimize the fuzzy logic controller. An artificial earthquake load was generated for numerical simulation. A simplified numerical model of damped outrigger system was developed. Based on numerical analyses, it has been shown that the semi-active damped outrigger system can effectively reduce both displacement and acceleration responses of the tall building in comparison with a passive outrigger damper system.

• Earthquakes and Structures
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• v.19 no.4
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• pp.227-241
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• 2020

An experimental study has been carried out to investigate the effect of beam to column connection rigidity on the behavior of infilled steel frames. Five half scale, single-story and single-bay specimens, including four infilled frames, as well as, one bare frame, were tested under in-plane lateral cyclic reversal loading. The connections of beam to column for bare frame as well as two infill specimens were rigid, whereas those of others were pinned. For each frame type, two different infill panels were considered: (1) masonry infill, (2) masonry infill strengthened with shotcrete. The experimental results show that the infilled frames with pinned connections have less stiffness, strength and potential of energy dissipation compared to those with rigid connections. Furthermore, the validity of analytical methods proposed in the literature was examined by comparing the experimental data with analytical ones. It is shown that the analytical methods overestimate the stiffness of infilled frame with pinned connections; however, the strength estimation of both infilled frames with rigid and pinned connections is acceptable.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.1
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• pp.176-187
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• 2001

Most bridges have expansion joints to accommodate thermal expansion and contraction without inducing large forces in the bridges. To evaluate the effects of earthquake-induced at expansion joints of concrete bridges, the first part of this paper deals with a collinear impact between concrete segments, which have the same cross section but different lengths. Especially, impact force, momentum, strain energy and kinetic energy are formulated in mathematically. These results are then used in the second part of this paper to simulate a realistic yet simple analysis of seismic pounding in concrete bridges. Analysis of seismic pounding in idealized concrete bridges is carried out by using a simple lumped-mass model and rationally determined values of the coefficient of restitution and the duration of impact.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.165-172
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• 1996

Recently, the response of a high-rise building to external dynamic force created by wind and earthquake has received much attention. This response is dependent on wind intensity, surrounding environment, building size, shape, mass, stiffness and amount of energy dissipation available in the system. The study has been done on these parameters. Attempts have been made to increase the damping in building system and thereby reduce structural response. These attempts have centered on adding an energy-dissipative system(passive tuned mass damper; passive TMD) to the building system and increasing the overall effective damping. In this paper the optimum condition of passive TMD will be derived with respect to random excitation and the properties of the optimum condition will have been studied.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.719-728
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• 2015

Following the Fukushima accident, a special safety inspection was conducted in Korea. The inspection results show that Korean nuclear power plants have no imminent risk for expected maximum potential earthquake or coastal flooding. However long- and short-term safety improvements do need to be implemented. One of the measures to increase the mitigation capability during a prolonged station blackout (SBO) accident is installing injection flow paths to provide emergency cooling water of external sources using fire engines to the steam generators or reactor cooling systems. This paper illustrates an evaluation of the effectiveness of external cooling water injection strategies using fire trucks during a potential extended SBO accident in a 1,000 MWe pressurized water reactor. With regard to the effectiveness of external cooling water injection strategies using fire engines, the strategies are judged to be very feasible for a long-term SBO, but are not likely to be effective for a short-term SBO.