• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.42 no.5
• /
• pp.711-721
• /
• 2022

Due to a long-term pandemic of COVID-19 since 2019, our society finally goes into 'un-tact (non-contact) era' in earnest by increasing an importance of non-contacted activities which are able to live without contacts among people. Un-tact era has influenced to generate a huge structural change with digitalization in our daily life as well as industrial society based on digital twin as an essential technology. As a technology representing real world in virtual digital world by integrating various technologies applied to 4^th industrial revolution, digital twin leads an innovation in industrial society with diverse industrial processes. But this technique isn't actively used across all industries due to structural limitations and environmental restrictions of digital twin. Especially, the field of construction and facility is necessary to use digital twin because it requires periodic managements of buildings in daily life and is directly connected with casualties in cases of disaster. But issues faced in reality are acting as an obstacle for applying digital twin. Therefore, this study suggests the necessity applying digital twin in facility safety response based on these issues and emphasizes active applications of digital twin by describing the expected effects being created. Furthermore, it connects to create demands of digital twin by overcoming current issues and suggesting high sustainable development.

• Journal of Korea Water Resources Association
• /
• v.54 no.spc1
• /
• pp.1167-1181
• /
• 2021

In relation to the algae bloom, four types of blue-green algae that emit toxic substances are designated and managed as harmful Cyanobacteria, and prediction information using a physical model is being also published. However, as algae are living organisms, it is difficult to predict according to physical dynamics, and not easy to consider the effects of numerous factors such as weather, hydraulic, hydrology, and water quality. Therefore, a lot of researches on algal bloom prediction using machine learning have been recently conducted. In this study, the characteristic importance of water quality factors affecting the occurrence of Cyanobacteria harmful algal blooms (CyanoHABs) were analyzed using the random forest (RF) model for Bohyeonsan Dam and Yeongcheon Dam located in Yeongcheon-si, Gyeongsangbuk-do and also predicted the occurrence of harmful blue-green algae using the machine learning and deep learning models and evaluated their accuracy. The water temperature and total nitrogen (T-N) were found to be high in common, and the occurrence prediction of CyanoHABs using artificial neural network (ANN) also predicted the actual values closely, confirming that it can be used for the reservoirs that require the prediction of harmful cyanobacteria for algal management in the future.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.6
• /
• pp.319-327
• /
• 2023

This study analyzes the risks of explosions of small LPG storage tanks installed at highway rest areas. For this purpose, the ranges of the effect of thermal radiation and overpressure caused by the BLEVE(Boiling Liquid Expansion Vapor Explosion)and VCE(Vapor Cloud Explosion) of a 2900-kg small LPG storage tank installed at highway rest areas were quantitatively evaluated by applying the Areal Location of Hazardous Atmospheres program. The ranges of influence of the derived explosion overpressure and thermal radiation were found to have a maximum radii of 336 m and 423 m, respectively. The study determined that those within 269 m could be severely injured by an explosion overpressure of 3.5 psi, and fatalities from thermal radiation of 10 kw/m² could occur within 192 m of the exploded storage tank. The safety management plan for the LPG storage tank was discussed while considering the auxiliary facilities of highway rest areas and the extent of the damage impact. These research results will help improve safety accident prevention regulations considering the environment and facilities of the rest areas as well as the safety management of small LPG storage tanks installed at highway rest areas.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.5
• /
• pp.40-48
• /
• 2023

In this paper, a sensor-based monitoring system was established to analyze the long-term behavioral characteristics of the caisson quay wall, a representative structural type in port facilities. Data was collected over a period of approximately 10 months. Based on existing literature, anomalous behaviors of port facilities were classified, and a measurement system was selected to detect them. Monitoring systems were installed on-site to periodically collect data. The collected data was transmitted and stored on a server through LTE network. Considering the site conditions, inclinometers for measuring slope and crack meters for measuring spacing and settlement were installed. They were attached to two caissons for comparison between different caissons. The correlation among measured data, temperature, and tidal level was examined. The temperature dominated the spacing and settlement data. When the temperature changed by approximately 50 degrees, the spacing changed by 10 mm, the settlement by 2 mm, and the slope by 0.1 degrees. On the other hand, there was no clear relationship with tidal level, indicating a need for more in-depth analysis in the future. Based on the characteristics of these collected database, it will be possible to develop algorithms for detecting abnormal states in gravity-type quay walls. The acquisition and analysis of long-term data enable to evaluate the safety and usability of structures in the event of disasters and emergencies.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.23 no.2
• /
• pp.69-78
• /
• 2024

Recently, the use of CCTV to prevent crowd accidents has been promoted, but research is needed to compensate for the spatial limitations of CCTV. In this study, pedestrian density was measured using drone footage, and based on a review of existing literature, a threshold of 6.7 people/m² was selected as the cutoff risk level for crowd accidents. In addition, we conducted a preliminary study to determine drone parameters and found that the pedestrian recognition rate was high at a drone altitude of 20 meters and an angle of 60°. Based on a previous study, we selected a target area with a high concentration of pedestrians and measured pedestrian density, which was found to be 0.27~0.30 per m². The study shows it is possible to measure risk levels by determining pedestrian densities in target areas using drone images. We believe drone surveillance will be utilized for crowd safety management in the near future.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.44 no.1
• /
• pp.95-100
• /
• 2024

The public survey performance review conducted by the Spatial Information Quality Management Institute is conducted at the screening rate in accordance with the regulations, and the examiner directly judges the overall trend of the submitted performance based on the extracted sample. However, the evaluation of the Ministry of Land, Infrastructure and Transport, the evaluation trustee shall be specified by random extraction (Random Collection) is specified by the sample. In this study, it analyzed the details of the actual site and analyzed through securing actual performance review data. In addition, we analyzed considerations according to various field conditions and studied ways to apply the public survey performance review sampling algorithm. Therefore, detailed sampling criteria analysis by performance reviewers is necessary. A relative comparison was made feasible by comparing the data for which the real performance evaluation was performed with the outcomes of the Python automation program. This automation program is expected to be employed as a foundation program for the automated application of public survey performance evaluation sampling in the future.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.28 no.3
• /
• pp.47-58
• /
• 2024

This study were conduced experimentally to analyze the heat-generating performance, flexural strength, and microstructure of conductive mortar mixed with micro steel fiber and multi-wall carbon nanotube (MWCNT). In the conductive mortar heat-generating performance and flexural strength tests, the mixing concentration of MWCNT was selected as 0.0wt%, 0.5wt%, and 1.0wt% relative to the weight of cement, and micro steel fibers were mixed at 2.0vol% relative to the volume. The performance experiments were conducted with various applied voltages (DC 10V, 30V, 60V) and different electrode spacings (40 mm, 120 mm) as parameters, and the flexural strength was measured at the curing age of 28 days and compared and analyzed with the normal mortar. Furthermore, the surface shape and microstructure of conductive mortar were analyzed using a field emission scanning electron microscope (FE-SEM). The results showed that the heat-generating performance improved as the mixing concentration of MWCNT and the applied voltage increased, and it further improved as the electrode spacing became narrower. However, even if the mixing concentration of MWCNT was added up to 1.0 wt%, the heat-generating performance was not significantly improved. As a result of the flexural strength test, the average flexural strength of all specimens except the PM specimen and the MWCNT mixed specimens was 4.5 MPa or more, showing high flexural strength due to the incorporation of micro steel fibers. Through FE-SEM image analysis, Through FE-SEM image analysis, it was confirmed that a conductive network was formed between micro steel fibers and MWCNT particles in the cement matrix.

• The Korean Society of Law and Medicine
• /
• v.23 no.4
• /
• pp.29-74
• /
• 2022

As social disasters occur under the Disaster Management Act, which can damage the people's "life, body, and property" due to the rapid spread and spread of unexpected COVID-19 infectious diseases in 2020, information collected through inspection and reporting of infectious disease pathogens (Article 11), epidemiological investigation (Article 18), epidemiological investigation for vaccination (Article 29), artificial technology, and prevention policy Decision), (3) It was used as an important basis for decision-making in the context of an infectious disease crisis, such as promoting vaccination and understanding the current status of damage. In addition, medical policy decisions using infectious disease data contribute to quarantine policy decisions, information provision, drug development, and research technology development, and interest in the legal scope and limitations of using infectious disease data has increased worldwide. The use of infectious disease data can be classified for the purpose of spreading and blocking infectious diseases, prevention, management, and treatment of infectious diseases, and the use of information will be more widely made in the context of an infectious disease crisis. In particular, as the serious stage of the Disaster Management Act continues, the processing of personal identification information and sensitive information becomes an important issue. Information on "medical records, vaccination drugs, vaccination, underlying diseases, health rankings, long-term care recognition grades, pregnancy, etc." needs to be interpreted. In the case of "prevention, management, and treatment of infectious diseases", it is difficult to clearly define the concept of medical practicesThe types of actions are judged based on "legislative purposes, academic principles, expertise, and social norms," but the balance of legal interests should be based on the need for data use in quarantine policies and urgent judgment in public health crises. Specifically, the speed and degree of transmission of infectious diseases in a crisis, whether the purpose can be achieved without processing sensitive information, whether it unfairly violates the interests of third parties or information subjects, and the effectiveness of introducing quarantine policies through processing sensitive information can be used as major evaluation factors. On the other hand, the collection, provision, and use of infectious disease data for research purposes will be used through pseudonym processing under the Personal Information Protection Act, consent under the Bioethics Act and deliberation by the Institutional Bioethics Committee, and data provision deliberation committee. Therefore, the use of research purposes is recognized as long as procedural validity is secured as it is reviewed by the pseudonym processing and data review committee, the consent of the information subject, and the institutional bioethics review committee. However, the burden on research managers should be reduced by clarifying the pseudonymization or anonymization procedures, the introduction or consent procedures of the comprehensive consent system and the opt-out system should be clearly prepared, and the procedure for re-identifying or securing security that may arise from technological development should be clearly defined.

• Korean Journal of Remote Sensing
• /
• v.37 no.6_2
• /
• pp.1819-1827
• /
• 2021

Land-use/cover change caused by rapid urbanization in South Korea is one of the concerns in flood risk management because groundwater recharge by precipitation hardly occurs due to an increase in impermeable surfaces in urban areas. This study investigated the hydrologic effects of land-use/cover on groundwater recharge in the Yeonje-gu district of Busan, South Korea. A statistical time series analysis was conducted with temporal variations of precipitation and groundwater level to estimate lag-time based on correlation coefficients calculated from auto-correlation function (ACF), cross-correlation function (CCF), and moving average (MA) at five sites. Landform and land-use/cover within 250 m radius of the monitoring wells(GW01, GW02, GW03, GW04, and GW05) at five sites were identified by land cover and digital map using Arc-GIS software. Long lag-times (CCF: 42-71 days and MA: 148-161 days) were calculated at the sites covered by mainly impermeable surfaces(GW01, GW03, and GW05) while short lag-times(CCF: 4 days and MA: 67 days) were calculated at GW04 consisting of mainly permeable surfaces. The results suggest that lag-time would be one of the good indicators to evaluate the effects of land-use/cover on estimating groundwater recharge. The results of this study also provide guidance on the application of statistical time series analysis to environmentally important issues on creating an urban green space for natural groundwater recharge from precipitation in the city and developing a management plan for hydrological disaster prevention.

• Journal of the Society of Disaster Information
• /
• v.18 no.1
• /
• pp.182-193
• /
• 2022

Purpose: By measuring and evaluating the risk of biodiesel through non-volatile residue (NVR) and flash point and explosion limit measurement at a specific temperature according to ASTM test standards, the risk of chemical fire causative substances is identified and a universal evaluation method By derivation and securing the risk-related data of the material, it can be used for the identification and analysis of the cause of the fire, and it can be applied to the risk assessment of other chemical substances Method: In order to measure the risk of biodiesel, it was measured using the non-volatile residue(NVR) measurement method, which measures how much flammable liquid is generated at a specific temperature. Heating was tested by applying KS M 5000: 2009 Test Method 4111. In addition, the flash point was measured using the method specified in ASTM E659-782005, and the energy supply method was measured using the constant temperature method. In addition, the explosion limit measurement was conducted in accordance with ASTM E 681-04 「Standard test method for concentration limits of flammability of chemicals(Vapors and gases)」 test standard. Result: As a result of checking the amount of combustible liquid by the non-volatile residue (NVR)measurement method, the non-volatile residue(NVR) of general diesel when left at 105±2℃ for 3 hours was about 30% (70% of volatile matter) and about 4% of biodiesel. In addition, similar results were obtained for the non-volatile residue(NVR)heating temperature of 150±2℃, 3 hours and 200±2℃ for 1 hour, and white smoke was generated at 200℃ or higher. In addition, similar values were obtained as a result of experimentally checking the explosion (combustion) limits of general diesel, general diesel containing 20% biodiesel, and 100% biodiesel. Therefore, it was confirmed that the flammability risk did not significantly affect the explosion risk. Conclusion: The results of this study suggested the risk judgment criteria for mixtures through experimental research on flammable mixtures for the purpose of securing the effectiveness, reliability, and reproducibility of the details of the criteria for determining dangerous substances in the existing Dangerous Materials Safety Management Act. It will be possible to provide reference data for the judgment criteria for flammable liquids that are regulated in the field. In addition, if the know-how for each test method is accumulated through this study, it is expected that it will be used as basic data in the research on risk assessment of dangerous substances and as a basis for research on the determination of dangerous substances.