• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.302-308
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• 2022

The PdO nanoparticle with large surface area was selected to solve the environmental pollution problem at fire range caused by high energy explosives research department explosive (RDX) and high melting explosive (HMX). By simulating water pollution, RDX and HMX nitramine explosives were dissolved in water, followed by the degradation reaction at 313 K by adding PdO. In order to measure the degradation reaction rate of explosives, ¹H NMR was used, which can monitor the reaction rate without losing sample during reaction, and observe the progress of the reaction through the spectrum. The results showed that the degradation of RDX and HMX by PdO nanoparticles are pseudo-first order reaction. The degradation of explosives compounds were observed via the chemical shift and peak intensity analysis of NMR peaks. The measured rate constants for these reactions of RDX and HMX were 2.10 × 10^-2 and 6.35 × 10^-4 h^-1, respectively. This study showed that the application of PdO nanoparticles for explosives degradation is a feasible option.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.5
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• pp.639-650
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• 2022

In areas where large-scale sediment transport occurs, it is important to apply appropriate countermeasure method because the phenomenon tends to accelerate by time duration. Among the various countermeasure methods applied so far, beach nourishment needs to be reviewed as an erosion prevention measure because the erosion pattern is mitigated and environmentally friendly depending on the particle size. In the case of beach nourishment. a detailed review is required to determine the size, range, etc., of an appropriate particle diameter. In this study, we investigated the characteristics of the related topographic change using the change in the particle size of nourishment materials, the application of partial area, and the condition under the coexistence of waves and wind as variables because those factors are hard to be analyzed and interpreted within results and limitation of that the existing numerical models are not able to calculate and result out so that it is required that phenomenon or efforts are reviewed at the same time through physical model experiments, field monitoring and etc. So we attempt to reproduce the tendency of beach erosion and deposition and predict possible phenomena in the future using machine learning techniques for phenomena that it is not able to be interpreted by numerical models. we used the hydraulic experiment results for the training data, and the accuracy of the prediction results according to the change in the training method was simultaneously analyzed. As a result of the study it was found that topographic changes using machine learning tended to be similar to those of previous studies in short-term predictions, but we also found differences in the formation of scour and sandbars.

• Journal of Adhesion and Interface
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• v.23 no.3
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• pp.87-93
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• 2022

To analyze the interfacial property between the fiber and the matrix, work of adhesion was used generally that was calculated by surface energies. In this paper, it was determined what types of contact angle measurement methods were more accurate between static and dynamic contact angle measurements. 4 types of glass fiber and epoxy resin were used each other to measure the contact angle. The contact angle was measured using two types, static and dynamic contact angle methods, and work of adhesion, W_a was calculated to compare interfacial properties. The interfacial property was evaluated using microdroplet pull-out test. Generally, the interfacial property was proportional to work of adhesion. In the case of static contact angle, however, work of adhesion was not consistent with interfacial property. It is because that dynamic contact angle measurement comparing to static contact angle could delete the error due to microdroplet size to minimize the surface area as well as the meniscus measuring error.

• Fisheries and Aquatic Sciences
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• v.25 no.9
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• pp.473-488
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• 2022

To have a better understanding of the impact of the PETRONAS oil and gas platform on commercial fisheries activities, Universiti Malaysia Terengganu (UMT) examined two approaches which are data collection from satellite and data collection from fishermen and anglers. By profiling the anglers who utilize reefed oil and gas structures for fishing, it can determine if the design and location of the reef platforms will benefit or negatively impacts those anglers and fisherman. Furthermore, this assessment will be contributing to the knowledge regarding the value of offshore oil and gas platforms as fisheries resources. Collectively, the apparent fishing activity data included, combined with the findings in the reefing viability index will help to inform PETRONAS's future decommissioning decisions and may help determine if the design and proposed locations for future rigs-to-reefs candidates would benefit commercial fishing groups, further qualifying them as appropriate artificial reef candidates. The method applied in this study is approaching by using a data satellite known as Google's Global Fishing Watch technology, which is one of the applications to measure commercial fishing efforts around the globe. The apparent commercial fishing effort around the selected twelve PETRONAS platforms was analyzed from January 2012 to December 2018. Using the data collection from fishermen which is the total estimation of commercial fish value cost (in Malaysia ringgit, MYR [RM]) in Peninsular Malaysia Asset, Sabah Asset, and Sarawak Operation region. The data were extracted every month from 2016 to 2018 from the National Oceanic and Atmospheric Administration database. Most of the selected platforms that show a high frequency of vessels around the year are platform KP-A, platform BG-A and platform PL-B. The estimated values of commercial fishes varied between platforms, with ranged from RM 10,209.92 to RM 89,023.78. Thus, platforms with high commercial fish value are selected for reefing in-situ and will serve multi-purposes and benefit the locals as well as the country. The current study has successfully assessed the potential reefing area of the Malaysian offshore environment with greater representativeness and this paper focused on its potential as a new fishing ground.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.3
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• pp.179-189
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• 2022

Ice and water droplets rise and fall above the freezing altitude under the effects of strong updrafts and downdrafts, grow into hail, and then fall to the ground in the form of balls or irregular lumps of ice. Although such hail, which occurs in a local area within a short period of time, causes great damage to the agricultural and forestry sector, there is a paucity of domestic research toward predicting hail. The objective of this study was to introduce Land-Atmosphere Modeling Package (LAMP) hail prediction and measure its performance for 50 hail events that occurred from January 2020 to July 2021. In the study period, the frequency of occurrence was high during the spring and during afternoon hours. The average duration of hail was 15 min, and the average diameter of the hail was 1 cm. The results showed that LAMP predicted hail events with a detection rate of 70%. The hail prediction performance of LAMP deteriorated as the hail prediction time increased. The radar reflectivity of actual cases of hail indicated that the average maximum reflectivity was greater than 40 dBZ regardless of altitude. Approximately 50% of the hail events occurred when the reflectivity ranged from 30~50 dBZ. These results can be used to improve the hail prediction performance of LAMP in the future. Improved hail prediction performance through LAMP should lead to reduced economic losses caused by hail in the agricultural and forestry sector through preemptive measures such as net coverings.

• Journal of the Society of Disaster Information
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• v.17 no.1
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• pp.176-183
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• 2021

Purpose: The introduction of smart factories that reflect the 4th industrial revolution technologies such as AI, IoT, and VR, has been actively promoted in Korea. However, in order to solve various problems arising from existing file-based operating systems, this research will focus on identifying and verifying non-file system-based data protection technology. Method: The research will measure security storage that cannot be identified or controlled by the operating system. How to activate secure storage based on the input of digital key values. Establish a control unit that provides input and output information based on BIOS activation. Observe non-file-type structure so that mapping behavior using second meta-data can be performed according to the activation of the secure storage. Result: First, the creation of non-file system-based secure storage's data input/output were found to match the hash function value of the sample data with the hash function value of the normal storage and data. Second, the data protection performance experiments in secure storage were compared to the hash function value of the original file with the hash function value of the secure storage after ransomware activity to verify data protection performance against malicious ransomware. Conclusion: Smart factory technology is a nationally promoted technology that is being introduced to the public and this research implemented and experimented on a new concept of data protection technology to protect crucial data within the information system. In order to protect sensitive data, implementation of non-file-type secure storage technology that is non-dependent on file system is highly recommended. This research has proven the security and safety of such technology and verified its purpose.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.517-529
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• 2021

This study analyzes changes in the efficiency of the Department of Early Childhood Education in Korea to examine the effectiveness of the National Evaluation for Teacher Education Institution. We provide policy implications from exploring factors influencing efficiency and comparing characteristics of efficient and inefficient departments. With 149 Department of Early Childhood Education in Korea, DEA was conducted to estimate the relative efficiency, and the Tobit model was applied to explore factors affecting efficiency. The results confirm that the Department of Early Childhood in Korea is run efficiently, though there was no change in scale efficiency and relative efficiency after the two phases of the National Evaluation for Teacher Education Institution. The results show the number of books per student was significantly lower despite a significantly higher employment rate. Efficiency of college departments, department greater than 60 (per cohort), and department in metropolitan city (except Seoul area) is confirmed greater. These results provide policy implications on developing evaluation measure and processes to improve education quality and efficiency.

• Journal of the Korea Society of Computer and Information
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• v.28 no.1
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• pp.49-54
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• 2023

The Global Positioning System (GPS) was developed for military purposes and developed as it is today by opening civilian signals (GPS L1 frequency C/A signals). The current satellite orbits the earth about twice a day to measure the position, and receives more than 3 satellite signals (initially, 4 to calculate even the time error). The three-dimensional position of the ground receiver is determined using the data from the radio wave departure time to the radio wave Time of Arrival(TOA) of the received satellite signal through trilateration. In the case of navigation using GPS in recent years, a location error of 5 to 10 m usually occurs, and quite a lot of areas, such as apartments, indoors, tunnels, factory areas, and mountainous areas, exist as blind spots or neutralized areas outside the error range of GPS. Therefore, in order to acquire one's own location information in an area where GPS satellite signal reception is impossible, another method should be proposed. In this study, IMU(Inertial Measurement Unit) combined with an acceleration and gyro sensor and a geomagnetic sensor were used to design a system to enable location recognition even in terrain where GPS signal reception is impossible. A method to track the current position by calculating the instantaneous velocity value using a 9-DOF IMU and a geomagnetic sensor was studied, and its feasibility was verified through production and experimentation.

• Journal of the Korean Institute of Gas
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• v.26 no.6
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• pp.16-23
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• 2022

In this study, characteristics of effect on hydrogen gas was investigated to hydrogen embrittlement by disk and tensile tests. The developed and commercial alloy was fabricated to a plate material made from an alloy ingot. The prepared materials were processed in the form of a disk to measure rupture pressure by hydrogen and helium gas at a rate of 0.1 to 1,000 bar/min. In the hydrogen pre-charged tensile test, a specimen was hydrogenated using an anode charging method, and the yield strength, ultimate tensile strength, elongation, and reduction in area rate were carried by a strain rate test. Also, the microstructure was observed to the fracture surface of the tensile test specimen. As a result, the developed materials satisfied endurable hydrogen embrittlement, and the fractured surface showed a brittleness fracture surface with a depth of several ㎛, but dimple due to ductile fracture could be observed.

• Korean Journal of Heritage: History & Science
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• v.55 no.2
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• pp.232-249
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• 2022

The purpose of this article is to review the status of designation and preservation, management of national prehistoric sites and to suggest future applications. Prior to the discussion, the overall status of national prehistoric sites was reviewed. Specifically, the current status of designation, designated area, and distribution by region of national prehistoric sites according to the period and nature of the sites were examined in detail. Next, in order to understand the preservation and management of national prehistoric sites, I report the results of field trips to several sites, such as Geomdan-ri in Ulju, Songguk-ri in Buyeo, and Seoktaek-ri in Hongseong, and propose some measures for preservation, maintenance, and management of the remains. Finally, by referring to cases of US national historic sites such as protection, conservation, operation and management system and academic research project of cultural heritage, it is necessary to consider the need for a direction of the utilization that considers both socio-economic aspects as well as education and research on cultural heritage. The active use of cultural heritage can be a measure that leads to the continuous preservation and management of the sites, and ultimately will be a shortcut to increasing the value of national prehistoric sites.