PURPOSES : In this study, an existing speed-controlled Marshall stability tester was systemized as an Internet of Things(IoT) system. The Marshall stability test data were transmitted to the cloud in real-time, and an IoT optional-controlled board capable of additional load and displacement control was proposed. METHODS : The IoT systemization was built based on an improvement of an IoT height measuring system, the re-verification of standard samples for comparative analysis, and the development of a wireless IG-IoT board. The developed wireless Induk-GeoTS(IG)-IoT board was compared with existing commercial data logger using displacement- and load- calibration equipment. After the conformity of the developed wireless IoT board was established, a urethane standard sample was reproduced and verified using the recipe presented in a previous study to conduct a round-robin test. In addition, the adequacy of the speed, load, and displacement control tests for the optional-controlled characteristics was verified. the round-robin test for the Marshall stability and deformation strength and the comparative test of indirect tensile strength with the existing Marshall tester were performed using the re-verified standard sample. RESULTS : The improved two-point IoT height measurement system reduced the average relative error by 2.11% relative to the one-point measurement. From the re-verification results of the regenerated urethane standard sample, it was suitable with relative error of 3.65% in the loading elastic modulus and 4.07% in the unloading elastic modulus, compared to the existing standard sample. From the comparative analysis of the developed wireless IG-IoT board and existing commercial data logger, it was confirmed that the wireless IoT board could be reliably used, based on the average relative error of the wireless IoT board, 0.64% and that of the data logger, 3.79% in terms of the displacement(flow value) and an average relative error of 0.78% for the wireless IoT board and 0.79% for the data logger in terms of the load(stability). By analyzing the optional-controlled characteristics, it was found that the Marshall stability speed control conditions were satisfied based on the error results, with an average relative value of 2.96% under deformation strength test condition of 30mm/min, 3.23% under the indirect tensile strength test condition of 50mm/min, and 2.6% under the Marshall stability test condition of 50.8mm/min. It was also found that proper control characteristics were obtained, with an average relative error of 0.72% within the experimental load range in the load control conditions, and an average relative error of 2.4% in the experimental displacement range in the displacement control conditions. The results from the round-robin Marshall stability and deformation strength testing to verify the applicability of the IoT optional-controlled board show that the data were reliable based on the 3σ quality control method. In addition, by comparing the results of the indirect tensile strength tests, the usability of the wireless IG-IoT board was verified, with an average relative error of 0.96%. CONCLUSIONS : The IoT height measuring system was improved, and a wireless IG-IoT board that can transmit test data to a cloud platform was developed. The usability of the developed wireless IoT board was verified by round-robin testing using a re-verified urethane specimen. The IG-IoT optional-controlled board extends the verified wireless IG-IoT board, it was developed and validated for not only the existing speed control, but also for load, and displacement control.

PURPOSES : The aim of this study is to review freeze-and-thaw testing apparatuses, develop a freeze-and-thaw testing setup with a test protocol, test the freeze-and-thaw properties of soils collected from different parts of South Korea, and suggest an index for frost susceptibility criteria for soils found in South Korea. METHODS : Based on a literature review, a new freeze-thaw testing setup was developed. In addition, a test protocol was developed for freeze-thaw testing. Soils collected from different parts of South Korea and bedding sand used for block pavements were tested to determine whether the measurements from the newly developed test setup could capture important freeze-thaw characteristics of the soils. Finally, to develop local frost susceptibility criteria, a parameter including both the vertical deformation and thermal conductivity characteristics of the soils was suggested. RESULTS : The results from the laboratory experiments indicate that the newly developed freeze-and-thaw setup captures the required parameters to quantify the responses of soils subjected to cyclic freeze-and-thaw testing. In addition, a vertical deformation of up to 2.437 mm is measured. Moreover, seven soils out of the nine tested soils are classified as having a medium frost susceptibility, whereas the remaining two show low frost susceptibility. The bedding sand experiment also shows that there is a possibility of having a frost susceptible condition based on the moisture content. When submerged, the bedding sand is classified as having a medium frost susceptibility. CONCLUSIONS : The "HEART" freeze-thaw testing setup was able to capture the parameters required for evaluating the frost susceptibility of soils. This setup and testing procedure could be further used to test and prepare criteria for classifying the frost susceptibility of soils found in South Korea.

The ship security accidents that occur in ships, at sea, and in ports have become increasingly more serious in recent years, and in particular, maritime terrorism and the abduction by pirates are emerging as an international problem. Accordingly, the International Maritime Organization implemented a measures to enhance ship security by adopting SOLAS Chapter 11-2, ISPS-code in 2004. In this study, it was investigated whether JDS-S4, a directional sound receiver developed for responding to ship security accident, has durability and safety suitable for ships. For the purpose, the conducted emission test (CE102) of the US military standard test (MIL-STD-461F) was performed, and it was confirmed that JDS-S4 satisfies the test conditions sufficiently.

In this study, a mixed resin containing Bis-GMA was developed to produce a light-emitting sign using quantum dots. As a result of measuring the viscosity, color coordinates change, and luminance of the mixed resin, the following conclusions were obtained. The viscosity of the mixed resin decreased as the content of the diluent increased, and viscosity values ​​ranged from 3,627 to 1,349cps showed as a result. The viscosity of the mixed resin decreased as the temperature increased, and the viscosity showed a value of 5,156 to 1,132cps. For the optical properties of InP/GaP/ZnSe/ZnS quantum dots, the absolute quantum efficiency was 91% at 522nm and 90% at 618nm when the gallium was 0.01%. The luminance of the light-emitting sign using the resin mixed with quantum dots was showed 142.6cd/m2 in white and 104.2cd/m2 in the red region.

PURPOSES : The purpose of this study is to establish a scientific and rational structure pavement maintenance technique and management standard through field investigation and analysis method development for measuring damage to structure pavement such that fundamental quality improvement can be promoted and the life of pavement prolonged. METHODS : In this study, the crack, plastic deformation, IRI, and SPI values measured using the existing RoadScanner of a corresponding section, as well as the relative dielectric constant values of a lower deck measured using a ground penetrating radar are reduced. The results of a small impact load test are verified by comparing the modulus of elasticity measured. RESULTS : In the Hongjecheon Overpass, when comparing the suspicion points of deterioration between the center of the lane and the 25 measurement data points of the wheel pass section based on the elastic modulus of the light falling weight deflectometer (LFWD), it is discovered that the lane comprises four centers (16%) and 18 wheelpaths (72%). The percentage of suspected deterioration points in the center is higher than that in the wheelpath. In addition, in the case of the Seoho Bridge, by comparing the suspicious points of deterioration for 11 measurement data points in the middle of the lane and the wheelpath section based on the elastic modulus of the LFWD, it is discovered that five points (45%) in both the middle of the lane and the wheel pass are similar. CONCLUSIONS : In this study, a comparative analysis of the LFWD elastic modulus and SPI factors (crack rate, plastic deformation, and IRI) of the Hongjecheon Overpass and Seoho Bridge is conducted to confirm the factors of pavement breakage. Among them, it is confirmed that it affects the pavement condition the most; however, to consider the LFWD elastic modulus as an evaluation criterion for future structure pavement, the data points must be verified via additional experiments to ensure high reliability.