• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1011-1017
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• 2023

In this study, the harmless crack size (a_hml) by double shot peening (DSP) using shot balls with different diameters was evaluated on carburized, quenched-tempered SCM822H steel. The minimum crack size (a_NDI) detectable by non-destructive inspection was also evaluated. The relationship between the crack size (a_25,50) that reduces the fatigue limit by 25% and 50% and a_hml was evaluated. The residual stress of DSP was greater in SP_(0.6+0.08) than SP_(0.8+0.08) and appeared deeper in the depth direction. In addition, the hardness below the surface appeared larger. The fatigue limit of DSP increased 2.07 times and 1.95 times compared to non-SP. All a_hml of the DSP specimen was determined at the depth (a). The compressive residual stress distribution affects a_hml, and the a_hml of SP_(0.6+0.08), which has a large compressive residual stress and a high fatigue limit, appeared large. a_hml of SP_(0.6+0.08) introduced deeper than the residual stress of SP_(0.8+0.08) is larger in the range of As=1.0-0.3. Since the residual stress in the thickness direction has a greater effect on a_hml than the residual stress at the surface, it is necessary to introduce it more deeply. The relation of a_hml, a_25,50, and a_NDI were evaluated in the point for safety and reliability.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.63-71
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• 2024

Through the development of construction technology, various construction projects such as redevelopment projects, undergrounding of roads, expansion of subways, and metro railways are being carried out. However, this has led to an increase in the number of construction projects in existing urban centers and neighborhoods, resulting in an increase in the number of damages and disputes between neighboring buildings and residents, as well as an increase in safety accidents due to the aging of existing buildings. In this study, digital data was applied to a graphics program to objectify the progress of cracks by comparing the creation of cracks and the increase in length and width through photographic images and presenting the degree of cracks numerically. Through the application of the program, the error caused by the subjective judgment of crack change, which was mentioned as a shortcoming of the existing field survey, was solved. It is expected that the program can be used universally in the building diagnosis process by improving its reliability if supplemented and improved in the process of use. As a follow-up study, it is necessary to apply the extraction algorithm of the digital graphic data program to calculate the length and width of the crack by itself without human intervention in the preprocessing work and to check the overall change of the building.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8357-8362
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• 2015

The emergency call device has been installed and operated for the elevator passenger safety, but the call can not be connected or delay to the operator in an emergency. The application of the Internet of Things(IoT) technology is required for the systematic management and reliability of the emergency call device installed in the elevator. To meet these requirements it is necessary to apply the RMS(Remote Management System). Emergency call device periodically reports the operating status information and the emergency call history information of the emergency call device to the RMS in the PSTN(Public Switched Telephone Network) environment, and transmits the call request information in an emergency. RAS(Remote Access Server) plays a role of converting the PSTN signals to TCP / IP. RMS reports a significant outbreak call and abnormal operating conditions to administrators. In this study, we developed optimized protocol to PSTN environment that is required by RMS and implemented its differentiated process. And a RAS-RMS Protocol was added to the Application Layer. Development protocol consisting of simple structure as compared to CoAP, MQTT or HTTP can work properly in low-spec CPU and transmit elevator emergency key information easily.

• Journal of Internet Computing and Services
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• v.16 no.6
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• pp.97-107
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• 2015

Up until recently, Korea has ranked the first place in UN e-Government Survey for three consecutive years. In keeping with such accomplishment, the size of budget execution has been consistently growing in accordance with Korea's Government 3.0 policy and vision, leading to increase in big-sized informatization projects in the business. Especially in mission critical public sector's infrastructure where it affects many people, growing demand for establishing high-quality information system with new technologies being brought to attention in order to meet the complex needs of citizens. National defense information system, being one of representative domains examples in the concerned area, established high military competency by applying breakthrough technology. Network-oriented national defense knowledge informatization was set as the vision in order to implement core roles in making efficient national defense management; and effort has been made to materialize the vision by making advancement in national defense's information system and its informatization implementation system. This research studies new quality index relevant to test and evaluation (T&E)of informatization business in national defense which is the representative example of mission critical public sector's infrastructure. We studied international standards and guidelines, analyzed actual T&E cases, and applied them to the inspection items that are currently in use, complying with the e-government law (Act No. 12346, Official Announcement Date 2014. 1.28., Enforcement Date 2014. 7.29.) As a result of productivity analysis, based on hypothesis in which suggested model was applied to T&E of the national defense informatization business, we confirmed the possibility of enhancement in the T&E productivity by assessing reliability, expertise, and safety as evaluation factors.

• Tunnel and Underground Space
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• v.19 no.3
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• pp.203-212
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• 2009

The prediction of near field behavior around an underground high-level radioactive waste repository is important for the repository design as well as the safety assessment. In this study, a sensitivity analysis for seven parameters consisted of design parameters and material properties was carried out using a three-dimensional finite difference code. From the sensitivity analysis, it was found that the effects of borehole spacing, tunnel spacing, cooling time and rock thermal conductivity were more significant than the other parameters. For getting a statistical distribution of buffer and rock temperatures around the repository, an artificial neural network, backpropagation, was applied. The reliability of the trained neural network was tested with the cases with randomly chosen input parameters. When the parameter variation is within ${\pm}10%$, the prediction from the network was found to be reliable with about a 1% error. It was possible to calculate the temperature distribution for many cases quickly with the trained neural network. The buffer and rock temperatures showed a normal distribution with means of $98^{\circ}C$ and $83.9^{\circ}C$ standard deviations of $3.82^{\circ}C$ and $3.67^{\circ}C$, respectively. Using the neural network, it was also possible to estimate the required change in design parameters for reducing the buffer and rock temperatures for $1^{\circ}C$.

• The Journal of Engineering Geology
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• v.28 no.2
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• pp.297-312
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• 2018

In order to assess the safety diagnosis and grouting reinforcement effect of old reservoir facility, local governments and public offices mainly use electrical resistivity survey. However, electrical resistivity survey is a qualitative evaluation that varies the resistivity value by various exploration conditions. It is also difficult to grasp the stiffness change directly related to the stability of reservoir, thus an electrical resistivity survey is not applicable to continuous stability monitoring after grouting. The purpose of this study is to investigate and validate the quantitative evaluation of reinforcement effect of reservoir with cement grouting through shear velocity (Vs), which is closely related to the stiffness (${\mu}$) of the ground. This study was carried out on two reservoir facilities. The reinforcement effect was evaluated by comparing the permeability test, standard penetration test, down-hole test and MASW(Multi-channel Analysis of Surface wave) survey before and after cement grouting. Shear wave velocity changes before and after grouting were analyzed by phase velocity difference and inversion analysis, respectively, and the reliability of the analytical results was evaluated by comparing with field test results. Shear wave velocity increases to 5~10% in case of the D levee, and 10~20% in the levee of H reservoir. These results are showed similar pattern to the field test results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.6159-6166
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• 2012

A discharge measurement is difficult in flood season which is especially important in the water resources field and the continuous discharge measurement for all rivers is impossible on the present system. So, the stage-discharge curve has been used for a long time to produce discharge data of rivers. However, there has been problems from a reliability angle due to the fact that this method uses only stage-discharge relationship, although the stage-discharge curve has the convenience. Therefore, a new mean velocity equation was derived by using Chiu's 2D velocity formula of the entropy concept in this paper. The derived equation reflected hydraulic characteristics such as the depth, gravity acceleration, hydraulic radius, energy slope, kinematic coefficient of viscosity, etc. and estimated also a maximum velocity. In addition, this method verified the relationship between a mean and maximum velocity and estimates an equilibrium state ${\phi}(M)$ well presenting properties of a river cross section as the results. The mean velocity was estimated by using the equilibrium state ${\phi}(M)$, and then the discharge was estimated. To prove this equation to be accurate, the comparison between the measured and estimated discharge is conducted by using the measured laboratory data in the unsteady condition flow showing loop state and the results are consistent. If this study is constantly carried out by using various laboratory and river data, this method will be widely utilized in water resources field.

• Journal of Environmental Health Sciences
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• v.46 no.2
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• pp.136-149
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• 2020

Objectives: The purpose of this study was to perform an aggregate human risk assessment for benzene in an industrial complex using the CalTOX model and to improve the reliability and predictability of the model by analyzing the uncertainty and sensitivity of the predicted assessment results. Methods: The CalTOX^TM 4.0 beta model was used to evaluate a selected region, and @Risk 7.6 software was used to analyze uncertainty and sensitivity. Results: As a result of performing the aggregate risk assessment on the assumption that 6.45E+04 g/d of benzene would be emitted into the atmosphere over two decades, 3% of the daily source term to air remained in the selected region, and 97% (6.26E+04 g/d) moved out of the region. As for exposure by breathing, the predicted LADD_inhalation was 2.14E-04 mg/kg-d, and that was assessed as making a 99.99% contribution to the LADD_total. Regarding human Risk_cancer assessment, the predicted human cancer risk was 5.19E-06 (95% CI; 4.07E-06-6.81E-06) (in the 95th percentile corresponding to the highest exposure level, a confidence interval of 90%). As a result of analyzing sensitivity, 'source term to air' was identified as the most influential variable, followed by 'exposure time, active indoors (h/day)', and 'exposure duration (years)'. Conclusions: As for the results of the human cancer risk assessment for the selected region, the predicted human cancer risk was 5.19E-06 (95% CI; 4.07E-06-6.81E-06) (in the 95th percentile, corresponding to the highest exposure level, a confidence interval of 90%). As a result of analyzing sensitivity, 'source term to air' was found to be most influential.

• Journal of Korean Society of Transportation
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• v.29 no.1
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• pp.39-46
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• 2011

Speeding is a major cause of traffic accidents that affects the safety of pedestrians and harms drivers and their families, property and mental health. However, most researches on speeding behavior have been conducted by survey method, so the relationship between cause and effect is not clear. The reliability of the research cannot be carefully examined because most researches involve retrospective methods. It is clear that conducting experimental research is important for overcoming these limitations, but it is impossible to perform tests with real cars in real traffic situations due to the inability to control situational factors (e.g., other vehicles, traffic signal) which affect participants' behavior. A car simulator experiment was designed and the theory of planned behavior was applied to the experiment. Each participant was grouped and assigned to either high speeding intention group or low speeding intention group according to their levels of speeding intention and analyzed the difference of driving behavior indexes between two groups. The results revealed statistically significant differences between two groups on driving speed, speeding frequency, and accelerator pressure deviation. Finally, the limitations and the implications of this study were discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.552-562
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• 2020

This study examined the effects of apartment complex management and residential quality on the residents' residential satisfaction and recommendation intentions. A survey was conducted on the residents of an apartment complex in Doan, Daejeon. Statistical analysis was analyzed using the SPSS 25.0 program. Exploratory factor analysis (EFA) was carried out to verify the validity of the measurement tools for apartment complex management, residential quality, living satisfaction, and recommendation intention. The Cronbach's α coefficient was evaluated to verify the reliability of the measurement tools. Multi-regression analyses were conducted to verify the research hypotheses. As a result, the following main results were derived. First, maintenance factors and living management factors among apartment complex management factors were found to have a significant effect on the residents' residential satisfaction. Second, among the factors of residential quality in apartment complexes, convenience, safety, comfortability, and economy had a significant effect on residential satisfaction. Third, residential satisfaction had a significant effect on the recommendation intention. Overall, the factors of apartment complex management and residential quality affecting residential satisfaction and recommendation intentions were derived.