PURPOSES : The objective of this study is to investigate the spatiotemporal factors influencing the waiting time of special transportation systems for disabled people in Seoul, Korea. METHODS : A parametric survival analysis was employed to identify the primary factors influencing longer waiting times, primarily because censoring data were included in the analysis. For the analysis, one-year historical data collected from the Seoul Call-taxi for the disabled in 2019 were used. Using normal probability plots and Anderson-Darling statistics, a log-normal model was estimated to fit the data. RESULTS : In terms of time, there was a time zone in which the service level in terms of waiting time, such as late-night and dawn, decreased depending on the time of day called by call taxi users with disabilities in Seoul. Moreover, the waiting time on weekends was shorter than on weekdays. Spatially, when a user requests a service, there are many nearby vehicles when the traffic conditions nearby are good, and the waiting time tends to decrease near the depot. CONCLUSIONS : The existing system needs to reflect the increase in vulnerable times and the improvement of the dispatch method, considering the difference in the primary purpose of travel on weekdays and weekends. Additionally, to resolve the phenomenon in which vehicles are concentrated in a specific area, waiting time can be improved using operational strategies that can uniformly distribute vehicles in space, such as spatial subdivision of depots, real-time monitoring, and relocation.

A telesounder is a device that can monitor the appearance of fish in the sea on land and store fish detection data. This study was conducted to monitor the appearance of fish resources in coastal or near seas by using LTE communication for data transmission of the telesounder. The purpose of this study was to develop a prototype telesounder that can monitor the appearance of fish groups in the waters about 50 km away from the coast and store fish detection data. In this study, the prototype telesounder including a fish finder, communication device and battery for stable operation at sea was developed. The stability of telesounder buoy, data transmission/reception and expected use time were investigated. The expected use time of the telesounder using LTE communication with a lithium battery (12 V, 120 Ah) was about 274 hours under the conditions of 10 minutes off and 10 minutes on, about 520 hours under the conditions of 30 minutes off and 10 minutes on, and about 142 hours under continuous conditions. As a result of the sea test, it was found that the telesounder can be used in the sea area moved about 34 km from the land and the telesounder buoy was evaluated to have secured basic stability (buoyancy balance, waterproof, antenna strength, etc.) for operation in a marine environment.

Recently, wideband acoustic technology has been introduced and started to be used in fisheries acoustic surveys in various waters worldwide. Wideband acoustic data provides high vertical resolution, high signal-to-noise ratio and continuous frequency characteristics over a wide frequency range for species identification. In this study, the main characteristics of wideband acoustic systems were elaborated, and a general methodology for wideband acoustic data analysis was presented using data collected in frequency modulation mode for the first time in Republic of Korea. In particular, this study described the data recording method using the mission planner of the wideband autonomous acoustic system, wideband acoustic data signal processing, calibration and the wideband frequency response graph. Since wideband acoustic systems are currently installed on many training and research vessels, it is expected that the results of this study can be used as basic knowledge for fisheries acoustic research using the state-of-the-art system.

Gamma Reality Inc. (GRI) provides real-time, mobile 3D radiation mapping, data fusion, and visualization technologies for applications ranging from nuclear power and decommissioning to emergency response. The GRI-LAMP is a compact, multi-sensor system weighing about 10 lbs (4.5 kg). LAMP is fully mobile, provides 360 degree imaging (only limited by physical access to objects/area), and streams the 3D map fused with radiation data in real-time to the control tablet for immediate results that can quickly inform the user of potential hazards in the area or direct the user to the specific location where efforts should be focused. GRI systems are also remotely deployable on robotic platforms and are used on unmanned aerial vehicles (UAS), unmanned ground vehicles (UGV), as well as on manned vehicles and in handheld configurations. This deployment flexibility coupled with real-time data maximizes dose reduction opportunities and further enables dynamic operational planning, which can help reduce the costs of managing and maintaining operational nuclear power plants, as well as decontaminating, or decommissioning nuclear facilities. Applications include, but are not limited to, conducting regular radiation surveys, hotspot localization, shielding verification, radioactive waste shipment surveys, contamination mapping, and dose measurement. GRI’s solutions enable faster, safer, and more efficient radiation detection, mapping, and visualization of source terms and contamination. Commercially available LAMP versions include gamma-ray imaging, dual neutron and gamma mapping, and non-imaging gamma-ray mapping options.

Currently, the development of evaluation technology for vibration and shock loads transmitted to spent nuclear fuel and structural integrity of spent nuclear fuel under normal conditions of transport is progressing in Korea by the present authors. Road transportation tests using surrogate spent nuclear fuel were performed in September, 2020 using a test model of KORAD-21 transportation cask and sea transportation tests were conducted from September 30 to October 4, 2021. In order to investigate amplification or attenuation characteristics, according to the load transfer path, a number of accelerometers were attached on a ship cargo hold, cradle, cask, canister, disk assembly, basket, and surrogate fuel assemblies and to investigate the durability of spent nuclear fuel rods, strain gages were attached on surrogate fuel assemblies. A ship named “JW STELLA” which has similar deadweight (5,000 ton) of existing spent nuclear fuel transportation ships was used for the sea transportation tests. The ship is propelled by 1,825 hp two main engines with two 4-bladed propellers. There are two major vibration sources in the ship. One is the vibration from waves and the other is the vibration from the engine and propeller system. The sensor locations on the ship were determined considering the vibration sources. The sea transportation test was performed for 5 days, the test data were measured successfully. The ship with the test model was departed from Changwon and sailed to Uljin, sailed west to Yeonggwang and then returned to Changwon. In addition to sailing on a designated test route, circulation test, braking/acceleration test, depth of water test, and rolling test were conducted. As a result of the preliminary data analysis of the sea test, power spectral densities and shock response spectrums were obtained according to the different test conditions. The vibratory loads caused by the wave mainly occurred in the frequency range of 0.1 to 0.3 Hz. The vibratory loads caused by the propeller occurred near the n/rev rotating frequencies, such as 5, 10, 20 Hz etc. However, those frequencies are far from the natural frequencies of local mode of the fuel rods, so it is considered that the vibratory loads from the wave and the propeller do not have a significant influence on the structural integrity of the fuel rods. Among all the test cases, maximum strain occurred at SG31 near the bottom nozzle on the test; the magnitude was 73.62 micro strain. Based on the analyzed road and sea transportation test data, a few input spectra for the shaker table test will be obtained and the shaker table test will be conducted in 2022. It is expected that the detailed vibration characteristics of the assembly which were difficult to identify from the test results can be investigated.

NFDC (Nuclear Fuel and materials Data Center) developed standard reference data for oxidation of HANA-6 cladding material. Thermo-gravimetric analyzer (TGA) was used to measure oxidation, and the measuring device was self-calibrated using standard materials. The oxidation amount of the HANA6 cladding was measured in an oxidizing atmosphere in the temperature range of 400 to 700°C. Through this, oxidation data, oxidation rate model equation, and graph were developed. The uncertainty factors were analyzed from the oxidation model. The expanded uncertainty of oxidation data was calculated by evaluating the uncertainty for each uncertainty factor. The oxidation data produced in this study was self-rated through deliberation by a specialized committee of NFDC and third experts. It was finally registered as a reference standard through the technical committee of the National Reference Standards Center. It is believed that the standard reference data developed in this study will be helpful for increasing reliability and stability evaluation of nuclear fuel and spent fuel.

In order to enhance the transparency of nuclear power, the investigation of nuclear activities is important at the right time. And investigation of North Korea, one of safety measures for such a surveillance system seems essential in the near future. However, the inspection period is limited and the possibility of revisiting is unclear, so it seems easy to install and more reliable monitoring devices are needed. The seal is a security device for monitoring forgery and alteration in the IAEA easily but simple. Since the existing seal devices used by IAEA and KINAC can only be checked through onsite inspections whether it is damaged or not, there is a limit to immediate response in the event of an emergency such as the theft of nuclear materials and loss of Continuity of Knowledge. While the North Korea-U.S. talks and inter-Korean talks are slowly approaching the North Korea’s nuclear issue, it is judged that the inspection of North Korea’s nuclear weapons is not in the distant future. Accordingly, it is necessary to develop a customized seal device for managing and monitoring spent nuclear fuel that can be used for inspection of North Korea. The real-time active seal device consists of a seal equipped with a detection sensor, a translator, and a server, and the translator use wireless communication in consideration of ease of installation and management, respectively. The translator and server use wired communication for data sustainability. The seal device is designed to maintain continuity of knowledge (COK) through wireless communication in consideration of security even in the event of equipment damage, malfunction, and loss of power, while enabling location detection in case of theft or abnormality. Therefore, in this study, a technical investigation on remote data communication was conducted accordingly, and a data communication module for a small amount of broadband data communication was manufactured and applied. In addition, several tests were conducted to determine data integrity and location accuracy according to the communication range.

Along with the current rapid development of technology, object classification is being researched, developed, and applied to security systems, autonomous driving, and other applications. A common technique is to use vision cameras to collect data of objects in the surrounding environment. Along with many other methods, LiDAR sensors are being used to collect data in space to detect and classify objects. By using the LiDAR sensors, some disadvantages of image sensors with the negative influence on the image quality by weather and light condition will be covered. In this study, a volumetric image descriptor in 3D shape is developed to handle 3D object data in the urban environment obtained from LiDAR sensors, and convert it into image data before using deep learning algorithms in the process of object classification. The study showed the potential possibility of the proposal and its further application.

The use of heat exchangers in various applications such as chemical, air conditioning systems, fuel processing, and power industries is increasing. In order to improve the performance of the heat exchanger, the problem of bonding quality of the copper tube, which is a major member, is emerging. However, since the copper tube is in the form of a pipe, it is difficult to identify internal defects with external factors. In this study, a thermal imaging camera was used to develop and verify an algorithm for detecting defects in the brazing part, and in the process, the brazing performance characteristics were analyzed according to the electrode position, and finally, a learning model was developed and performance evaluation was performed. It was confirmed that the method of supplying heat to the base material and melting the filler metal through the heat transfer effect is more effective than supplying heat input to the filler metal in the bonding process of copper tubes through high-frequency induction heating brazing. Thermal image data was used to develop a defect discrimination model, and 80% of training data and 20% of test data were selected, and a neural network-based single-layer copper tube brazing defect discrimination model was developed through k-Flod cross-validation., the prediction accuracy of 95.2% was confirmed as a result of the error matrix analysis.