• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.606-611
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• 1999

Recently , the hydraulic fill method is commonly used in many reclamation projects due to lack of fill materialss. The method of hydraulic fill i recalmation is executed by transporting the mixture of water -soil particles into a relcaimed land through dredging pipes, then the dredged soil particels settle down in thewater orflow over an out flow weir with the water. The amount of the volume reductions of dredged soil is considered the sum of the overall settlement by descication shrinkage and self-weigth consolidation and the loss of soil particles flow over a weir. In the present study, hydrometer analysis was performed with the soil samples obtained bofore and after dredging to estimate the amount of soil particles residual at reclaimed area and the loss of soil particles , then it was suggested the method of determining the loss ratio of dredged soils from the tests results. The hydrometer analysis of in-situ soil samples showed that the loss ratio of dredged soils is lowest at the nearest point to dredge pipe and highest at the nearest point of out flow weir.

• Oral Biology Research
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• v.42 no.4
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• pp.216-221
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• 2018

The purpose of this study was to assess the clinical outcomes of active periodontal therapy (APT) and supportive periodontal therapy (SPT) through loss of teeth in the Korean patients with aggressive periodontitis. The number of missing and residual teeth, probing pocket depth were examined in 33 patients diagnosed with aggressive periodontitis at the baseline and who had participated in APT and SPT for 3 years or more. A 20 and 3 teeth were lost during the APT and SPT, respectively. The mean tooth loss rate of 0.13 per patient and year. There was no significant statistical difference in clinical improvement between the smoker and non-smoker groups. Within the limitation of this study, APT combined with supportive therapy could decrease the risk of tooth loss in patients suffering from aggressive periodontitis.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.5
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• pp.79-84
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• 2012

As the huge economical loss and function paralysis of information technology-based systems can be caused by the misoperation of residual current devices(RCDs) due to surge voltages and currents, RCDs shall not operate by surge currents. In this paper, in order to evaluate the reliability of residual current operated circuit-breakers with integral overcurrent protection for household and similar uses((RCBOs) stressed by surges, the unintended trip characteristics of RCBOs under surge currents were experimentally investigated using the combination wave generator. Seven different types of single-phase RCBOs being present on the domestic market were investigated according to KS C IEC 61009-1 standard. As a result, all kinds of specimens were satisfied the requirements for 0.5 [${\mu}s$]/100[kHz] ring wave impulse currents. Most of specimens stressed by the 8/20[${\mu}s$] impulse current tripped at least one or more, and some of them were broken down during consecutive tests. It was found that only one type of specimens meets the L-N mode immunity to the combination wave of 1.2/50[${\mu}s$] impulse voltage and 8/20[${\mu}s$] impulse current.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.6
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• pp.867-874
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• 2006

The goal of this study is to assess cast iron pipes (CIPs) and present a residual tensile strength prediction model using pit characteristics and fracture toughness. The results is the followings. First, average pit depths of collected CIPs were in the range from 0.63 to 6.49 mm, loss of tensile strength compared with net metallic tensile strength were from -7.06 to 67.91 percent. Second, fracture toughness for NS-CR-1, NS-CR-2, and NS(2)-CR-1 were in the range from 62.85 to $89.39kgf/mm^2{\sqrt{mm}}$, and average of those samples was $73.69kgf/mm^2{\sqrt{mm}}$ on CIPs. Third, the models developed in this study by using pit characteristics and fracture toughness showed a little good correlation for measured residual tensile strength, and the results will be expected to help for water utilities to manage CIPs in the aspect of rehabilitation and assessment of structural safety on CIPs.

• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.513-528
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• 2020

This paper presents the results of an experimental study on the residual behavior of reinforced recycled aggregate concrete (RRAC) beam-columns after exposure to elevated temperatures. Two parameters were considered in this test: (a) recycled coarse aggregate (RCA) replacement percentages (i.e. 0, 30, 50, 70 and 100%); (b) high temperatures (i.e. 20, 200, 400, 600, and 800℃). A total of 25 RRAC short columns and 32 RRAC beams were conducted and subjected to different high temperatures for 1 h. After cooling down to ambient temperature, the following basic physical and mechanical properties were then tested and discussed: (a) surface change and mass loss ratio; (b) strength of recycled aggregate concrete (RAC) and steel subjected to elevated temperatures; (c) bearing capacity of beam-columns; (d) load-deformation curve. According to the test results, the law of performance degradation of RRAC beam-columns after exposure to high temperatures is analyzed. Finally, introducing the influence coefficient of RCA replacement percentage and high temperatures, respectively, to correct the calculation formulas of bearing capacity of beam-columns in Chinese Standard, and then the residual bearing capacity of RRAC beam-columns subjected elevated temperatures is calculated according to the modified formulas, the calculated results are in good agreement with the experimental results.

• Structural Engineering and Mechanics
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• v.77 no.5
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• pp.673-689
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• 2021

This paper addresses the efficiency of thermal insulation layers applied to protect structural elements strengthened by fiber-reinforced polymers (FRP) in the case of fire event. The paper presents numerical modeling and nonlinear analysis of reinforced concrete (RC) columns externally strengthened by FRP and protected by thermal insulation layers when subjected to elevated temperature specified by standard fire tests, in order to predict their residual capacity and fire endurance. The adopted numerical approach uses commercial software includes heat transfer, variation of thermal and mechanical properties of concrete, steel reinforcement, FRP and insulation material with elevated temperature. The numerical results show good agreement with published results of full-scale fire tests. A parametric study was conducted to investigate the influence of several variables on the structural response and residual capacity of insulated FRP-confined columns loaded by service loads when exposed to fire. The residual capacity of FRP-confined RC column was affected by concrete grade and insulation material and was shown to improve substantially by increasing the concrete cover and insulation layer thickness. By increasing the VG insulation layer thickness 15, 32, 44, 57 mm, the loss in column capacity after 5 hours of fire was 30%, 13%, 7% and 5%, respectively. The obtained results demonstrate the validity of the presented approach for estimation of fire endurance and residual strength, as an alternative for fire testing, and for design of fire protection layers for FRP-confined RC columns.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2088-2095
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• 2023

The safety of nuclear installations is largely determined by the tightness of fuel elements cladding. As the Fukushima nuclear accident showed, the main task in case of loss of power supply is to ensure reliable removal of residual heat release from spent fuel pool (SFP) with irradiated fuel assemblies (IFAs). The paper presents the results of calculated-experimental studies and thermal-hydraulic modeling of temperature storage modes of IFAs in SFP. Experimental studies of SFP's temperature regime and calculated evaluation of residual heat removal due to the thermal conductivity of building structures surrounding the SFP were performed. To ensure the safe operation of research reactors, it's necessary to know the IFA's residual heat power (RHP) in the reactor and SFP, which is determined depending on the operating time of fuel assemblies (FAs) and the IFAs calculated holding time. The FAs operating time depends on the reactor energy output. The IFAs calculated holding time is determined by the fuel burnup, U-235 mass in the fuel, and reactor utilization factor. The IFAs fuel burnup was calculated using the MCU-PTR program. Also presented are the RHP's calculation results using some of the empirical dependencies. The concept of a passive heat removal system (PHRS) based on thermosyphon's operating principle was proposed.

• Steel and Composite Structures
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• v.45 no.3
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• pp.369-388
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• 2022

Composite effect between steel and recycled aggregate concrete (RAC) in steel reinforced-RAC (SRRAC) structures can effectively improve RAC's adverse mechanical properties due to the natural defects of recycled coarse aggregate (RCA). However, the performance of SRRAC after thermal exposure will have a great impact on the safety of the structure. In this paper, firstly, the mechanical properties of SRRAC structures after high temperatures exposure were tested, including 24 SRRAC columns and 32 SRRAC beams. Then, the change rules of beams and columns performance with the maximum temperature and replacement percentage were compared. Finally, the formulas to evaluate the residual bearing capacity of SRRAC beams and columns after exposure to high temperatures were established. The experimental results show that the maximum exposure temperature can be judged by the apparent phenomenon and mass loss ratio of RAC. After high temperatures exposure, the mechanical properties of SRRAC beams and columns change significantly, where the degradation of bearing capacity and stiffness is the most obvious. Moreover, it is found that the degradation degree of compression member is more serious than that of flexural member. The formulas of residual bearing capacity established by introducing influence coefficient of material strength agree well with the experimental results.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.119-119
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• 2001

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.4
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• pp.437-447
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• 2011

In patients who used removable partial dentures for a long period of time, gradual alveolar bone resorption occurs in edentulous area. However, in residual teeth area, alveolar bone is maintained sound. This causes an imbalance in intermaxillary distance between a maxillae and a mandible which is intensified due to expansion in vertical and horizontal bone amount difference between the two area as time passes. As the result, this shows a substantial difference in vertical position according to the period of teeth loss even after residual teeth loss. As in this situation, a patient with bilaterally and anterio-posteriorly different intermaxillary distance, various prosthodontic problems can be caused in fixed implant prosthodontics and implant overdenture. This study shows a case in which implant-supported removable partial denture was fabricated considering residual alveolar bone height after teeth loss in a patient who had been using a distal extension removable partial denture for a long period of time. In anterior area with short intermaxillary distance, fixed prosthodontics were fabricated with implant placement and in posterior area with long intermaxillary distance, a removable partial denture was fabricated. Finally, a small number of implants were placed without additional surgery and economical and comfortable treatment results were shown.