• 한국지진공학회논문집
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• 제17권2호
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• pp.79-88
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• 2013

Steel plate concrete (SC) composite structure is now being recognized as a promising technology applicable to nuclear power plants as it is faster and suitable for modular construction. It is required to identify its dynamic characteristics prior to perform the seismic design of the SC structure. Particularly, the damping ratio of the structure is one of the critical design factors to control the dynamic response of structure. This paper compares the criteria for the damping ratios of each type of structures which are prescribed in the regulatory guide for the nuclear power plant. In order to identify the damping ratio of SC shear wall, this study made SC wall specimens and conducted experiments by cyclic lateral load tests and vibration tests with impact hammer. During the lateral loading test, SC wall specimens exhibited large ductile capacities with increasing amplitude of loading due to the confinement effects by the steel plate and the damping ratios increased until failure. The experimental results show that the damping ratios increased from about 6% to about 20% by increasing the load from the safe shutdown earthquake level to the ultimate strength level.

• 국제초고층학회논문집
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• 제2권2호
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• pp.123-130
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• 2013

In the past two decades, researchers from different countries have conducted series of experimental and theoretical studies to investigate the behaviour of structures in fire. Many new insights, data and calculation methods have been reported, which form the basis for modern interdisciplinary structural fire engineering. Some of those methods are now adopted in quantitative performance-based codes and have been migrated into practice. Mainly based on the achievements in structural fire research at China, the Chinese national code for fire safety of steel structures in buildings has been drafted and approved, and will be released in this year. The code is developed to prevent steel structures subjected to fire from collapsing, ensure safe evacuation of building occupants, and reduce the cost for repairing the damages of the structure caused by fire. This paper presents the main contents of the code, which includes the fire duration requirements of structural components, fundamental requirements on fire safety design of steel components, temperature increasing of atmosphere and structural components in fire, loading effect and capacity of various components in fire, and procedure for fire-resistant check and design of steel components. The analytical approaches employed in the code and their validation works are also presented.

• 한국정밀공학회지
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• 제33권5호
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• pp.371-376
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• 2016

Safety related workers, such as firefighters, have to wear a protective helmet. The Development of Helmets for safety is in progress to promote the wearable device industry. Several accidents caused by negligence in recent days have raised public attention to safety. For this reason, the amount of national budget funding for the study of fire-fighting and smart safety helmets has increased. However, most previous studies have focused on safety, rather than the application of new technologies based on physical attributes, especially the characteristics of head shape and size, even though fire helmets play the critical role of protection from flames and external shocks etc. in an emergency. This paper will present the smart technologies and newly developed designs for safety helmets that are personalized for each firefighter, based on the characteristics of their head, and will help a rescue operation to be much more safe and efficient.

• Geomechanics and Engineering
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• 제18권3호
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• pp.277-289
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• 2019

In this study, an innovative anchoring approach has been developed dealing with all relevant aspects in consideration of previous works. An ultimate pulling force calculation of anchor is presented from a geotechnical point of view. The proposed umbrella anchor focuses not only on the friction resistance capacity, but also on the axial capacity of the composite end structure and the friction capacity occurring around the wedge. Even though the theoretical background is proposed, in-situ application requires high-level mechanical design. Hence, the required parts have been carefully improved and are composed of anchor body, anchor cap, connection brackets, cutter vanes, open-close ring, support elements and grouting system. Besides, stretcher element made of aramid fabric, interior grouting system, guide tube and cable-locking apparatus are the unique parts of this design. The production and placement steps of real sized anchors are explained in detail. Experimental results of 52 pullout tests on the weak dry soils and 12 in-situ tests inside natural soil indicate that the proposed approach is conservative and its peak pullout value is directly limited by a maximum strength of anchored soil layer if other failure possibilities are eliminated. Umbrella anchor is an alternative to conventional anchor applications used in all types of soils. It not only provides time and workmanship benefits, but also a high level of economic gain and safe design.

• 시스템엔지니어링학술지
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• 제14권2호
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• pp.58-66
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• 2018

This paper represents a systematic approach aimed at improving the performance of the proportional integral (PI) controller for the Advanced Power Reactor (APR) 1400 Feedwater Control System (FWCS). When the performance of the PI controller offers superior control and enhanced robustness, the steam generator (SG) level is properly controlled. This leads to the safe operation and increased the availability of the nuclear power plant. In this paper, a systems engineering approach is used in order to design a novel PI controller for the FWCS. In the reverse engineering stage, the existing FWCS configuration, especially the characteristics of the feedwater controller as well as the feedwater flow path to each SG from the FWCS, were reviewed and analysed. The overall block diagram of the FWCS and the SG was also developed in the reverse engineering process. In the re-engineering stage, the actual design of the feedwater PI controller was carried out using a genetic algorithm (GA). Lastly, in the validation and verification phase, the existing PI controller and the PI controller designed using GA method were simulated in Simulink/Matlab. From the simulation results, the GA-PI controller was found to exhibit greater stability than the current controller of the FWCS.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.337-344
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• 2019

The TRIGA fuel of the Philippine Research Reactor-1 (PRR-1) will be used in a subcritical reactor assembly (SRA) to strengthen and advance nuclear science and engineering expertise in the Philippines. SRA offers a versatile and safe training and research facility since it can produce neutrons through nuclear fission reaction without achieving criticality. In this work, we used a geometrically detailed model of the PRR-1 TRIGA fuel to design a subcritical reactor assembly and calculate physical parameters of different fuel configurations. Based on extensive neutron transport simulations an SRA configuration is proposed, comprising 44 TRIGA fuel rods arranged in a $7{\times}7$ square lattice. This configuration is found to have a maximum $k_{eff}$ value of $0.95001{\pm}0.00009$ at 4 cm pitch. The SRA is characterized by calculating the 3-dimensional neutron flux distribution and neutron spectrum. The effective delayed neutron fraction and mean neutron generation time of the system are calculated to be $748pcm{\pm}7pcm$ and $41{\mu}s$, respectively. Results obtained from this work will be the basis of the core design for the subcritical reactor facility that will be established in the Philippines.

• 대한건축학회논문집:계획계
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• 제33권12호
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• pp.19-28
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• 2017

The purpose of this study is to propose a design methodology to build temporary isolation rooms when infectious diseases suddenly occur in a certain region, such as the case of MERS-Cov in South Korea in 2015. Although most big hospitals usually have isolation rooms, they are expensive and dangerous to run such facilities on normal and typical days. To deal with these problems in this research, shipping containers are chosen as devices used to build the temporary isolation rooms near the original hospital. To do so, firstly, a prototype for the temporary isolation room was designed with the three part modules. The first part is for the medical team; the second part including the isolation rooms is for patients; the third part is for medical selection rooms to test the specimens. Secondly, the plan was compared with the MERS-Cov infection control guidelines. Finally this prototype is applied into the Yong-in Yon-sei severance hospital and then evaluated through a CFD simulation using STAR-CCM+(ver.9.06) for checking infectious bacterium movement in this prototype. The result showed that the prototype is effectively safe for patients tested as negative, patients waiting to be tested, and the medical team.

• 한국안전학회지
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• 제36권4호
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• pp.1-11
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• 2021

Piping systems comprising pumps and valves are essential in the power plant, oil, and defense industry. Their purpose includes a stable supply of the working fluid or ensuring the target system's safe operation. However, piping system accidents due to leakage of toxic substances, explosions, and natural disasters are prevalent In addition, with the limited maintenance personnel, it becomes difficult to detect, isolate, and reconfigure the damage of the piping system and recover the unaffected area. An autonomous recovery piping system can play a vital role under such circumstances. The autonomous recovery algorithms for the piping system can be divided into low-pressure control algorithms, hydraulic resistance control algorithms, and flow inventory control algorithms. All three methods include autonomous opening/closing logic to isolate damaged areas and recovery the unaffected area of piping systems. However, because each algorithm has its strength and weakness, appropriate application considering the overall design, vital components, and operating conditions is crucial. In this regard, preliminary research on algorithm's working principle, its design procedures, and expected damage scenarios should be accomplished. This study examines the characteristics of algorithms, the design procedure, and working logic. Advantages and disadvantages are also analyzed through simulation results for a simplified piping system.

• 한국안전학회지
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• 제37권2호
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• pp.43-53
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• 2022

This paper describes an attempt to improve and optimize the operational safety level of a domestic research reactor by conducting a probabilistic safety assessment (PSA) under full-power operating conditions. The PSA was undertaken to assess the level of safety at an operating research reactor in Korea, to evaluate whether it is probabilistically safe and reliable to operate, and to obtain insights regarding the requisite procedural and design improvements for achieving safer operation. The technical objectives were to use the PSA to identify the accident sequences leading to core damage, and to conduct sensitivity analyses based thereon to derive insights regarding potential design and procedural improvements. Based on the dominant accident sequences identified by the PSA, eight types of sensitivity analysis were performed, and relevant insights for achieving safer operation were derived. When these insights were applied to the reactor design and operating procedure, the risk was found to be reduced by approximately ten times, and the safety was significantly improved. The results demonstrate that the PSA methodology is very effective for improving reactor safety in the full-power operating phase. In particular, it is a highly suitable approach for identifying the deficiencies of a reactor operating at full power, and for improving the reactor safety by overcoming those deficiencies.

• Steel and Composite Structures
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• 제42권4호
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• pp.553-568
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• 2022

This paper explored the viability of utilising titanium alloy bolts in the construction industry through an experimental programme, where a total of sixty-six titanium alloy (Ti/6Al/4V) bolts were tested under axial tension, pure shear and combined tension and shear. In addition, a series of Charpy V-notch specimens machined from titanium alloy bolts, conventional high-strength steel bolts, austenitic and duplex stainless steel bolts were tested for impact toughness comparisons. The obtained experimental results demonstrated that the axial tensile and pure shear capacities of titanium alloy bolts can be reasonably estimated by the current design standards for steel structures (Eurocode 3, AS 4100 and AISC 360). However, under the combined tension and shear loading conditions, significant underestimation by Eurocode 3 and unsafe predictions through AS 4100 and AISC 360 indicate that proper modifications are necessary to facilitate the safe and economic use of titanium alloy bolts. In addition, numerical models were developed to calibrate the fracture parameters of the tested titanium alloy bolts. Furthermore, a design-based selection process of titanium alloy bolts in the structural applications was proposed, in which the ultimate strength, ductility performance and corrosion resistance (including galvanic corrosion) of titanium alloy bolts was mainly considered.