• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.97-105
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• 2009

This study was conducted for the purpose of examinating the safety and economical efficiency of large high tension bolted joints. The specimen using F10T-M30 large high strength bolts has been selected and static tensile test has been conducted to evaluate the slip characteristics. In addition, finite element analysis has been carried out to estimate the number of required bolts. As a result, the average slip coefficient of M30 high strength bolts exceeded 0.4 - the standard in highway bridge design specification - and has satisfied the slip strength, which is the same as that of M22 high strength bolts. In addition, if F13T-M22 high strength bolts were applied, the number of required bolts decreased by 21%, and if F10T-M30 high strength bolts were applied, the number of required bolts decreased by 46%, that leads to the conclusion that the economical efficiency in accordance with diametering of high strength bolts was now verified.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.3 s.55
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• pp.145-154
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• 2009

Steel-Concrete Composite Deck with I-beam welded is lighter and easier to construct than conventional in situ reinforced concrete slabs due to the I-beam embedded in the corrugated slab. For the calculation of effective flexural rigidity of conventional reinforced concrete structures, methods suggested in Design Standard for Roads and Bridges and ACI have been used. In this paper, the calculation methods were applied to steel-concrete composite deck with I-beam welded and then results of the steel-concrete composite deck were compared with those of reinforced concrete slabs. In addition, applicability of the methods to steel-concrete composite deck with I-beam welded was estimated. In order to compare the effective flexural rigidity, flexural experiments were conducted. Fifteen slabs were built and the variables considered in the experiments were studs, length of the slab, shape of the section and connecting methods.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.127-134
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• 2008

The response of a bridge can be influenced by span length, bridge's surface condition, vehicle's weight, and vehicle's velocity. It is difficult to predict accurate behavior of a bridge. In the current standard of specifications, such dynamic effect is defined by impact factor and prescribed to consider live load as to increase design load by means of multiplying this value by live load. However, it is not well understood because the Impact factor method differs from every country. Dynamic, static and pseudo-staitic field loading tests on PSC-I girder bridges were carried out to find out the dynamic property of the bridge. This paper is aimed to figure out actual dynamic property of the bridge by using field loading test. An empirical method based on impact factor is widely used and also argued. Displacement and strain response measured from the tests was compared with one from the empirical method. The former seems to be reasonable since it can consider actual response of a bridge through field tests.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.135-146
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• 2008

In this study, the effect of epoxy mortar panel as the shear strengthening material of reinforced concrete beam is investigated by loading test. The main variables are the kind of strengthening material, the amount of reinforcement and the spacing of CFS(Carbon Fiber Sheet) stirrups. The design method to use epoxy mortar panel as shear strengthening of reinforced concrete beam took the shear capacity as the form of the sum of $V_c$, $V_s$, $V_{sheet}$ and $V_p$. By making a comparison between the values calculated by the proposed shear strength prediction formula and those from the loading test results, the mean value was 1.10 and the standard deviation was 8.16%.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2002-2010
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• 2024

Korea Atomic Energy Research Institute (KAERI) has operated an integral effect test facility, the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS), with reference to the APR1400 (Advanced Power Reactor 1400) for tests for transient and design basis accidents simulation. A test for a loss of coolant accident (LOCA) at the top of the reactor pressure vessel (RPV) had been conducted at ATLAS to address the impact of the loss of safety injections (LSI) and to evaluate accident management (AM) actions during the postulated accident. The experimental data has been utilized to validate system analysis codes within a framework of the domestic standard problem program organized by KAERI in collaboration with Korea Institute of Nuclear Safety. In this study, the test has been analyzed by using thermal-hydraulic system analysis codes, MARS-KS 1.5 and TRACE 5.0 Patch 6, and a comparative analysis with experimental and calculation results has been performed. The main objective of this study is the investigation of the thermal-hydraulic phenomena during a small break LOCA at the RPV upper head with the LSI as well as the predictability of the system analysis codes after the AM actions during the test. The results from both codes reveal that overall physical behaviors during the accident are predicted by the codes, appropriately, including the excursion of the peak cladding temperature because of the LSI. It is also confirmed that the core integrity is maintained with the proposed AM action. Considering the break location, a sensitivity analysis for the nodalization of the upper head has been conducted. The sensitivity analysis indicates that the nodalization gave a significant impact on the analysis result. The result emphasizes the importance of the nodalization which should be performed with a consideration of the physical phenomena occurs during the transient.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.5
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• pp.367-375
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• 2024

Reefer containers experience a temperature deviation of 3℃ or more between the front, where the refrigerator is located, and the rear, where the container door is, due to external environmental factors. This temperature deviation significantly affects the freshness of cargo, particularly in the transportation of fresh goods. This study proposes a method to minimize temperature deviation by partially shielding the T-Floor. The test subjects were 40-feet reefer containers, and the design variables for the shielding rate were set at 0%, 50%, 60%, and 70%. The experiment results showed that with a T-Floor shielding rate of 60%, It was confirmed that the stabilization time decreased by 28.5% compared to the existing cutoff rate of 0%, and the standard deviation decreased by 42.9%. By minimizing the temperature deviation within the loading part, it is possible to prevent spoilage of fresh cargo during transportation.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.1316-1316
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• 2024

Greenhouses require various control systems to create an optimal environment, and from an architectural engineering perspective, the uniformity of the internal environment is crucial for crop growth. However, greenhouses are structurally exposed to external weather conditions, leading to a high probability of variations in temperature, humidity, CO2 levels, lighting, etc., across different zones within the greenhouse. Such non-uniformity can impact the growth rate, quality, and yield of crops, highlighting the necessity of maintaining a consistent environment within the greenhouse. To address this, experiments utilizing Computational Fluid Dynamics (CFD) simulations were conducted targeting greenhouses in Pocheon, South Korea, focusing on the central heating and cooling systems to propose an optimal design considering the uniformity of internal temperatures. Subsequently, validation was performed using measurements from temperature and humidity sensors within the greenhouses. The heating and cooling systems operate based on indoor temperatures, activating cooling when indoor temperatures exceed the set cooling temperature in summer and heating when temperatures fall below the set heating temperature in winter. A standard greenhouse model was set as case 1, and experiments were conducted by adjusting the position and spacing of the fabric ducts of the heating and cooling systems, resulting in six categorized cases. Variations in temperature and humidity distribution were observed among the cases, and quantitative analysis provided optimal positions and spacing for the fabric ducts. The results of this study can serve as foundational data for developing environmental control solutions for agricultural facilities.

• Journal of the Korea Institute of Building Construction
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• v.17 no.2
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• pp.175-181
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• 2017

The purpose of this study is evaluating the characteristics of tensile strength of UHPC and examining tensile performance of notched specimens by direct tensile test. For test variables, 120, 150, and 180MPa of target design standard strength were aimed at. With general water curing and $90^{\circ}C$ high temperature steam as curing conditions, the properties were reviewed. Overall, it was represented that the specimens of notch-type direct tensile strength concrete was effective in inducing central cracks compared with existing direct tension specimens. Through this, it was judged that data construction with high reliability was possible. Above all, in a graph of direct tensile strength and strain, in the case of steam curing at high temperature, there was great difference of initial tensile strength compared with water curing. As passing of ages, an aspect that the difference gradually decreased was shown. Maximum tensile strength was found to increase steadily with increasing age for all target design strengths in water curing, in the case of steam curing, the tendency to increase significantly due to the initial strength development effect at 7 days of age. The initial crack strength increases with age in case of underwater curing, in the case of steam curing, it was higher than that of water curing in 7 days, while the strength of 28 days was lowered. In this part, it is considered necessary to examine the arrangement condition of the steel fiber.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.199-206
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• 2016

The aim of this study was to establish the optimal conditions to design a shoe rack that could effectively sterilize and deodorize shoes contaminated by various bacteria. The manufacture and evaluation of a shoe rock was conducted for one year from October 2014 to September 2015. The antibacterial efficacies were evaluated using Escherichia coli and Staphylococcus aureus by JIS Z 2801:2010. The deodorization efficiency was identified by the standard method for deodorization efficiency evaluation of an indoor air cleaner established by Korea Air Cleaning Association, SPS-KACA002-132:2006. The results showed that antibacterial evaluation showed more than 99.9% of the sterilization effects on Escherichia coli and Staphylococcus aureus after exposure to ultraviolet (UV) light for 30 seconds. The average deodorization efficiency for the test gases was 42.5%. The temperature in the shoes and in the shoe rack was lower than $40^{\circ}C$ and $25^{\circ}C$, respectively, when the UV lamp was turned on for 5 minutes and off for 25 minutes repeatedly. This was controlled by turning the UV lamp on and off to maintain the appropriate temperature in the shoes. In conclusion, the real deodorization efficiency is expected to be higher than the measured value because the internal volume of the shoe rack was smaller than the test chamber used to measure the deodorization efficiency. The deodorization effect could be increased further by the sterilization of bacteria causing bad odors in shoes. Further studies will be needed to determine the temperature deviations within the shoe rack to provide constant conditions.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.1
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• pp.87-93
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• 2006

Inventories, and characteristics such as dimension, fuel rod array, weight, $^{235}U$ enrichment, and discharge burnup of spent nuclear fuel (SNF) generated from existing and planed nuclear power plants based on National 2nd Basic Plan for Electric Power Demand and Supply were investigated and projected to support geological disposal system design. The historical and projected inventory by the end 2057 is expected to be 20,500 and 14,800MTU for PWR and CANDU spent nuclear fuel, respectively. The quantity of SNF with initial $^{235}U$ enrichment of 4.5 wt.% and below was shown to be 96.5% in total. Average burnup of SNF revealed $\sim36$ GWD/MTU and $\sim40$ GWD/MTU for the period of 1994-1999 and 2000-2003, respectively. It is expected that the average burnup of SNF will be $\sim45$ GWD/MTU at the end of 2000's. From the comprehensive study, it was concluded that the imaginary SNF with $16\times16$ Korean Standard Fuel Assembly, cross section of $21.4cm\times21.4cm$, length of 453cm, mass of 672 kg, initial $^{235}U$ enrichment of 4.5 wt.%, discharge burnup of 55 GWD/MTU could cover almost all SNFs to be produced by 2057.