• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.19 no.1
• /
• pp.20-26
• /
• 2023

The defected baffle former bolts of Kori unit 1 were withdrawn to analyze the cause of damage and gamma-ray measurement is being scheduled. Prior to that, in order to calculate the specific radioactivity value of the baffle former bolt, a radioactivity calculation method considering the actual operation history of the nuclear power plant is introduced and the calculation results are shown. In particular, the radioactivity calculation method considering the operation history is obtained by defining the monthly contribution factor from the actual monthly operation history. As a result, the results considering operation history are 16-28% lower than the general radioactivity calculation results. These results can contribute to establish a reasonable but economical strategy when planning nuclear power plant decommissioning.

• Journal of the Korean Society of Radiology
• /
• v.14 no.5
• /
• pp.503-510
• /
• 2020

Concrete is one of the most widely used materials as the shielding structures of a nuclear facilities. It is also the most generated radioactive waste in quantity while dismantling facilities. Since the concrete captures neutrons and generates various radionuclides, radiation measurement and analysis of the sample was fulfilled prior to dismantle facilities. An HPGe detector is used in general for the radiation measurement, and effective correction factors such as geometrical correction factor, self-absorption correction, and absolute detector efficiency have to be applied to the measured data to decide exact radioactivity of the sample. Correction factors are obtained by measuring data using a standard source with the same geometry and chemical states as the sample under the same measurement conditions. However, it is very difficult to prepare standard concrete sources because concrete is limited in pretreatment due to various constituent materials and high density. In addition, the concrete sample obtained by core drill is a volumetric source, which requires geometric correction for sample diameter and self absorption correction for sample density. Therefore in recent years, many researchers are working on the calculation of effective correction factors using Monte carlo simulation instead of measuring them using a standard source. In this study we calculated, using Geant4, one of the Monte carlo codes, the correction factors for the various diameter and density of the concrete core sample at the gamma ray energy emitted from the nuclides ¹⁵²Eu and ⁶⁰Co, which are the most generated in radioactive concrete.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.26 no.3
• /
• pp.173-182
• /
• 2013

The building design projects which are being proceeded nowadays pursue a complex and various shape of structures, escaping from the traditional and regular shape of buildings. In this new trend of the architecture, there rises a demand of the research in the structural engineering for the effective realization of such complex-shaped buildings which disassembles the orthogonality of frames. As a distinguished characteristics of the buildings in a complex-shape, there frequently are inclined columns included in the structural frame. The inclined column causes extra axial force and bending moment at the beam-column connection so it is necessary to assess those effects on the structural behavior of the frame and the connection by experiment or analysis. However, with comparing to the studies on the normal beam-column connections, the inclined column connections have not been studied sufficiently. Therefore, this study evaluated the beam-column connections having an inclined column using nonlinear and finite element analysis method. In this paper, steel moment frames having inclined columns were analyzed by the nonlinear pushover analysis to check the global behavior and beam-column connection models were analyzed by the finite element analysis to check the buckling behavior and the fracture potentials.

• The Journal of the Convergence on Culture Technology
• /
• v.6 no.2
• /
• pp.55-70
• /
• 2020

This study aims to identify the influence of risk-inducing factors and safety inspection on the measures of reducing accidents among workers of building structures in small construction sites. The result can be summarized as follows: First, as for the influence of risk-inducing factors on human factors, preparation for work, disintegrating molds, taking follow-up measures, and keeping records, have statistically significant influences. Therefore, it can be said that safety inspection has a partial mediating effect in the relationship between risk-inducing factors and human factors. Second, as for the influence of risk-inducing factors on facility factors, preparation for work, and taking follow-up measures influenced significantly. This indicates that safety inspection has a partial mediating effect in the relationship between risk-inducing factors and facility factors. Third, as for the influence of risk-inducing factors on management factors, the installation of shores and risk assessment are found to have significant effects. This shows that safety inspection has a partial mediating effect in the relationship between risk-inducing factors and management factors. Fourth, the influence of risk-inducing factors on work factors was significant only in the installation of shores. This indicates that safety inspection has a completely mediating effect in the relationship between risk-inducing factors and work factors. Finally, in the relationship between risk-inducing factors and accident reduction measures, preparation for work, installation of shores, and taking follow-up measures showed significantly positive influences. In contrast, keeping records has a significant negative influence. Thus, safety inspection has a partial mediating effect in the relationship between risk-inducing factors and management factors.

• The Korean Journal of Archival Studies
• /
• no.73
• /
• pp.161-188
• /
• 2022

This article explores the current status of arrangement of the archives relating to the Korean Provisional Assembly held by the National Assembly Library and suggests the direction of rearrangement focusing on the principles of arrangement. The Korean Provisional Assembly had records management regulations, and records were produced and stored according to them. However, the archives lost their original order at some point. The National Assembly Library collected and managed them in the 1960s. The National Assembly Library did not fully consider the records management system at the time of record production and various situations that may occur during the storage process while organizing the collected archives. At that time, the National Assembly Library did not follow the records management regulations of the Korean Provisional Assembly. In addition, the hierarchical structure of archives was not applied during the arrangement, and the National Assembly Library arranged without considering the Principal of Provenance and the Principle of original order. As a result, it became difficult to understand the structure and context of the archives. In order to solve these problems and come up with a plan for rearranging the archives, first of all, it is necessary to examine the characteristics of the records related to the Korean Provisional Assembly in accordance with the principles of record arrangement. First, according to the Principal of Provenance, it is necessary to identify the organization, function, and records and classify the records item, records file, creators, dates of creation, types of records etc. Second, by applying the Principle of original order, it is necessary to understand what the order of records was at the time when records were created and preserved. Third, it is necessary to examine whether the records are completely created and valid. It is impossible to completely arrange the archives related to the Korean Provisional Assembly as it was in the past. However, by examining the current state of arrangement and the direction of rearrangement, it will be possible to newly understand the contents, structure, and context of the archives and create a basis for effective reference service.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.2 no.4
• /
• pp.314-320
• /
• 2014

Although the cement industry serves as the cornerstone of the construction industry by supplying one of its fundamental materials, it confronts new environmental challenges due to the problem of the $CO_2$ generated from raw materials and fuel used in the cement manufacturing process. Also, concrete structures can be decomposed and reused as construction materials. Simply in terms of the cyclic processing of $CO_2$, recycling waste concrete to manufacture recycled aggregate or recycling waste concrete powder, which is the material for cement can be considered optimally environment-friendly practices. This study contributes to the aim of manufacturing high value added materials that exploits the chemical properties of the waste concrete powder. From the research results, waste concrete powder is feasible to use to produce low carbon type recycled cement.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.89-92
• /
• 2008

The seismic behavior of the lightly reinforced concrete frames (LRCFs) was controlled by the nonductile behavior of the critical regions. These critical regions require retrofit to improve the seismic behavior of the lightly reinforced concrete frames. Critical column end regions must be retrofit to increase the global ductility capacity. The objective of this research is to evaluate structural strengthening performance of lightly reinforced concrete frame with Strain hardening cement composite(SHCC) experimentally. The experimental investigation consisted of a cyclic load tests on 1/3-scale models of precast infill walls. Reinforcement detail of infill wall was variables in the experiment. The experimental results, as expected, show that the multiple crack pattern, strength, ductility and energy dissipation capacity are superior for specimen with SHCC infill wall due to bridging of fibers and stress redistribution in cement matrix.

• Journal of the Korean GEO-environmental Society
• /
• v.15 no.9
• /
• pp.29-36
• /
• 2014

Under the situation that the seismic vulnerability are a worsening problem in many world's megacities, the disaster preparedness including earthquake hazards is a matter of primary concern in the capital city of Korea, Seoul. Especially, because it is hard to move or dismantle the architectural heritages, the mitigation of earthquake damages is potentially more difficult than other structures. Moreover, in order to decide the proper preparedness plan against future earthquakes, it is very important to understand how soils pass the seismic waves to architectural heritages. In this paper, therefore, the ground condition and depth of bedrock was investigated by the MASW-method at heritages located in Seoul. Then one-dimensional seismic response analysis was conducted based on the distribution of shear wave velocity. As the major result of analyses, peak acceleration, site amplification factor and natural period are proposed in each site for recurrence period.

• Explosives and Blasting
• /
• v.25 no.2
• /
• pp.1-10
• /
• 2007

In this paper, the 1/5 scale models of the reinforced concrete colunms were designed and fabricated. The influence of the number of blasting holes on the exposed length of steel bars and vertical load was investigated. The relation between the length of steel bar and the number of blasting holes was examined by performing the blast tests considering the vertical load on the scaled reinforced concrete columns. Weight of scaled column models by blasting and that of exposed was compared with the number of blasting holes. Finally, based on the exposed length of steel bars and vertical load, the number of blasting holes were calculated. Results shows that the number of blasting holes calculated in this study are suitable for scaled structure models test by blasting demolition.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.1
• /
• pp.96-102
• /
• 2007

Welding deformation causes critical problems under construction and in use of steel structures by varying the magnitude of the steel structures and deteriorating mechanic strength. Existing method to construct steel structures in civil engineering needs preassembly process for a part of or the whole structures on a broad space to examine the size of structures inevitably varied in the process of welding (assembly process). It leads to waste of time, space and human efforts, worry of safety accidents with the characteristic of the work to be performed on a high place, and non-efficiency and non-economy by using such supplementary equipments as crane. This paper, to remove the needless preassembly process by pre-estimating welding deformation produced under construction of large steel structures, devises a method modeling welded part for applying the equivalence load method and examines the effects of welding sequence and self weight on welding deformation by the method.