• Journal of Navigation and Port Research
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• v.43 no.6
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• pp.403-412
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• 2019

The characteristics of the manoeuvring motion of a ship are dependent on the ship type, as well as draft or speed in the same ship. In recent years, the number of extra-large vessels has increased significantly, which can cause enormous material and environmental damage in the event of a marine accident. Thus, the importance of ship maneuvering is increasing. The IMO has forced the officers to be trained in simulators through the STCW 95 amendment. However, FMSS is costly and difficult to access and the PC-based simulator has the disadvantage that only one person can engage in simulation. The purpose of this study was to solve the shortcomings of the FMSS and PC-based simulators by enabling multiple people to use their PCs to simulate based on a network. The simulator is implemented through the analysis and numerical calculation of the Nomoto model, Radar function mounting, data transfer protocol design, and GUI building. To verify the simulator, the simulation results were compared and analyzed with the test results of T.S. HANBADA according to the criteria of the Korean Register of Shipping(KR) and IMO standards for ship maneuverability. As a result, It showed a relative error of 0%~ 32.1% with an average of 13.7%, and it satisfied the IMO criteria for ship maneuverability.

• Composites Research
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• v.36 no.4
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• pp.253-258
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• 2023

Although the development of transportation means has realized the right to mobility for the disabled who have difficulty in moving, it can be said that the improvement of the safety of passengers with disabilities that can occur in a car accident is lower than that of ordinary passenger seats. In particular, in the case of a rear-end collision that can occur suddenly, it is a reality that disabled passengers are vulnerable to head and neck injuries. Therefore, in this study, a multi-layer headrest foam that divides the headrest into three parts in the coronal plane was proposed to improve the head and neck injury index of disabled passengers in the vehicle in the event of a rear-end collision of a wheelchair transport vehicle. A range of stress scale factors was selected to give various compressive characteristics of the foam through low-speed rear-end collision analysis through a simple model, and GA optimization was performed by specifying the range as a parameter. Through the optimization result, the phase relationship between HIC and NIC was analyzed according to the compression characteristics of the layers. HIC responded most sensitively to the compression characteristics of the front layer and NIC responded to the compression characteristics of the mid layer, and the compression characteristics of the rear layer showed the lowest. A normal headrest and an optimized multi-layer headrest were placed in the validation model to analyze the low-speed rear-end collision sled test, and HIC and NIC were derived lower in the multi-layer headrest than in the general headrest. The compression behavior of the multi-layer headrest was also clearly shown, and it was verified that the multi-layer headrest was effective in improving the injury index of the head and neck compared to the general headrest.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.39-46
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• 2020

Accident prevention is more important than follow-up, which is based on Heinrich's law. The marine incident system is a very meaningful system that can prevent similar accidents, and was introduced in 2010 in Korea in accordance with the enforcement of the Code for the Investigation of Marine Casualties and Incidents (CI Code). Based on the CI Code, ship owners or ship operators are required to notify the Central Chief Inspector using the designated notification form in the event of a marine incident, but the number of voluntary notifications is still small. In this regard, this study intends to provide a direction for improvement by conducting an in-depth analysis focusing on the lack of notification procedures and forms of the marine incident system. To this end, we analyzed related regulations, cases of excellent overseas shipping countries such as the United Kingdom and Singapore, cases of similar domestic transportation systems such as aviation and railways, and marine incident notification procedures and forms of leading shipping companies. Major improvements in the notification process include the transition of the marine incidents to voluntary reporting, the expansion of the reporting subjects, and the identification of the security of the informer's identity. The main contents of the notification form revision include the use of the term "reporting" instead of "notification," the content of the identity guarantee in the notification form, and the increase in statistical value through the expansion of optional entries.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.4
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• pp.215-229
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• 2023

In this study, non-destructive technologies that can be applied to evaluate the integrity of valve materials, safety against internal pressure caused by corrosion, and the blocking function of large-diameter water valves during operation without requiring specimen collection or manpower entering the inside of the valve were tested to assess the reliability of the technologies and their suitability for field application. The results showed that the condition of the graphite structure inside the valve body can be evaluated directly through the optical microscope in the field without specimen collection for large-diameter water butterfly valves, and the depth of corrosion inside the valve body can be determined by array ultrasound and the tensile strength can be measured by instrumented indentation test. The reliability of each of these non-destructive techniques is high, and they can be widely used to evaluate the condition of steel or cast iron pipes that are significantly smaller in thickness than valves. Evaluation of blocking function of the valves with mixed gas showed that it can be detected even when a very low flow rate of mixed gas passes through the disk along with the water flow. Finally, as a result of evaluating the field applicability of non-destructive technologies for three old butterfly valves installed in the US industrial water pipeline, it was found that it is possible to check the material and determine the suitability of large-diameter water valves without taking samples, and to determine the corrosion state and mechanical strength. In addition, it was possible to evaluate safety through the measurement results, and it is judged that the evaluation of the blocking function using mixed gas will help strengthen preventive response in the event of an accident.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.599-607
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• 2017

Since 2015, small and medium domestic enterprises that treat more than a certain quantity of chemical substances in accordance with the Chemical Substance Control Act are obliged to submit an off-site impact assessment and risk management plan. In order to reduce the administrative and economic burden of the risk assessment, its impact was determined. Toxic leaks of nitric acid, methanol, and acetic acid were estimated and the correlations (between them?) were calculated. In addition, the correlations of this study were used to compare the KORA results according to the accident scenarios of the actual workplace and the extent of the damage as a function of distance in the case of toxic leaks. In this study, the correlation formula of the materials can be used to quickly determine the damage distance in the event of the accidental leakage of materials in the road or workplace, and to prepare emergency plans and respond to emergencies more quickly.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.332-337
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• 2023

Korea is not only surrounded by the sea on three sides, but also has national and local rivers extending 26,843 km, so it has a geographical feature in which abundant sea and inland water surface coexist. As the number of ships operating in the inland waters is continuously increasing due to the improvement of national income, the risk of ship accidents and human casualties in the inland waters is also increasing. In this study, a macroscopic plan for the safety management of inland water ships was presented through investigation of inland water related laws and operation status analysis. As an improvement plan, as a hardware infrastructure it is proposed to secure sufficient inland water fire-boats to secure the golden time for early response to accidents and lifesaving, and to operate an institution specializing in the prevention of inland water ships accidents. And as a software infrastructure, establish departure control standards for inland water ships and the safety diagnosis system currently applied only to sea going ships, the introduction of a system tailored to the characteristics of inland water ships. The proposed inland water safety management policy is expected to contribute to the preparation of prompt and systematic countermeasures in the event of an inland water ship accident, and it is hoped that it will serve as an opportunity to continue to pay attention to safety-related research on inland water ships, which was briefly activated after the sinking of M/V Sewol.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.6
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• pp.853-861
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• 2018

This paper proposes the application of harmonic constraints to address the problems caused by abnormal voltage increases when electric railway vehicles are running. The AC line that supplies the train with power during operation is used to provide electricity of 25kV/60 Hz, but gradually the size and frequency of harmonics involved in the line are varied with the technological evolution of the railroad vehicle electrical equipment. An increase in heat losses due to the failure of the instrument transformer (PT), the main circuit device, which is a serious problem with the recent train safety operation, or to the main displacement voltage. When high frequency components are introduced through low frequency Transformers of the main circuit device, the high intensity of the components is caused by the high intensity of the core and the current flow of the parasitic core is increased, thus generating heat. To solve this problem, the recent adjustment of the sequence has applied artificial NOTCH OFF of the power converter. However, the method of receiving and controlling the OFF signal operates by interaction between the ground and the vehicle's devices, thus it is invalid in the event of failure, and an actual accident is occurring. Therefore, the harmonic currents were required to prevent possible flow of harmonics, and conducted a study to prevent accidental occurrence of train accidents and to verify feasibility of the device through the simulations of the train's experimental analysis and the simulations of the train for safe operation.

• Fire Science and Engineering
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• v.31 no.6
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• pp.67-73
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• 2017

An aircraft maintenance hangar is a building that stores, maintains, and inspects expensive aircraft. The frequency of fire occurrence is low, but the resulting human and material damage can be very serious. Therefore, in this study, we conducted a qualitative analysis of the fire safety of the currently operating fire suppression systems for aircraft maintenance hangars using the Fault Tree method, and then performed a quantitative analysis using the failure rate data for the derived basic events and analyzed the importance of the minimal cut sets. As a result of the qualitative analysis by the minimal cut set, it was found that there were 14 accident paths that could be expanded to a large fire, due to the fire control failure of the aircraft hangar fire suppression system. The quantitative analysis revealed that, the probability of the fire expanding into a large one is $2.08{\times}E-05/day$. The analysis of the importance of the minimal cut set shows that four minimal cut sets, namely the fire detector and foam head action according to the zone and blocking of the foam by the aircraft wing and the fire plume, had the same likelihood of causing the fire to develop into a large one, viz. 24.95% each, which together forms the majority of the likelihood. It was confirmed for the first time by fault tree method that the fire suppression system of aircraft maintenance hangars is not suitable for fires under the aircraft wings and needs to be improved.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.7
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• pp.199-204
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• 2021

Digital substation refers to a substation that digitizes functions and communication methods of power facilities such as monitoring, measuring, control, protection, and operation based on IEC 61850, an international standard for the purpose of intelligent power grids. Based on the intelligent operating system, efficient monitoring and control of power facilities is possible, and automatic recovery function and remote control are possible in the event of an accident, enabling rapid power failure recovery. With the development of digital technology and the expansion of the introduction of eco-friendly renewable energy and electric vehicles, the spread of direct current distribution systems is expected to expand. MVDC is a system that utilizes direct current lines with voltage levels and transmission capacities between HVDCs applied to conventional transmission systems and LVDCs from consumers. Converting existing lines in substations, where most power equipment is alternating current centric, to direct current lines will reduce transmission losses and ensure greater current capacity. The process bus of a digital substation is a communication network consisting of communication equipment such as Ethernet switches that connect installed devices between bay level and process level. For MVDC linkage to existing digital substations, the process level was divided into two buses: AC and DC, and a system that can be comprehensively managed in conjunction with diagnostic IEDs as well as surveillance and control was proposed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1161-1175
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• 2018

An unexpected event could be easily followed by a large secondary accident due to the limitation in sight of drivers in road tunnels. Therefore, a series of automated incident detection systems have been under operation, which, however, appear in very low detection rates due to very low image qualities on CCTVs in tunnels. In order to overcome that limit, deep learning based tunnel incident detection system was developed, which already showed high detection rates in November of 2017. However, since the object detection process could deal with only still images, moving direction and speed of moving vehicles could not be identified. Furthermore it was hard to detect stopping and reverse the status of moving vehicles. Therefore, apart from the object detection, an object tracking method has been introduced and combined with the detection algorithm to track the moving vehicles. Also, stopping-reverse discrimination algorithm was proposed, thereby implementing into the combined incident detection processes. Each performance on detection of stopping, reverse driving and fire incident state were evaluated with showing 100% detection rate. But the detection for 'person' object appears relatively low success rate to 78.5%. Nevertheless, it is believed that the enlarged richness of image big-data could dramatically enhance the detection capacity of the automatic incident detection system.