• Journal of the Korea Convergence Society
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• v.10 no.10
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• pp.107-115
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• 2019

Effective construction safety management systems are desperately required for reducing damage caused by increasing safety accidents in construction sites. Safety accidents in construction sites can effectively protect if proactive measures are taken to prevent unauthorized worker access the expected hazardous area. In this study, we have developed a IoT(Internet of Things)-based dangerous zone alarming system for safety management in construction sites, which can be operated at low cost in large-scale sites as well as small and medium-sized construction sites. The development system utilizes a Zigbee-based beacon technology and cellular mobile communication technology to detect when authorized workers, unauthorized field workers or outsiders approaches hazardous zones. If somebody approaches the dangerous zones the system notifies immediately to the safety manager with a danger warning signal. It is expected that this system can effectively prevent safety accidents when applied to construction sites.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.589-600
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• 2022

Investigations on the molten-pool sloshing behavior are of essential value for improving nuclear safety evaluation of Core Disruptive Accidents (CDA) that would be possibly encountered for Sodium-cooled Fast Reactors (SFR). This paper is aimed at synthesizing the knowledge from our recent studies on molten-pool sloshing behavior with solid particles conducted at the Sun Yat-sen University. To better visualize and clarify the mechanism and characteristics of sloshing induced by local Fuel-Coolant Interaction (FCI), experiments were performed with various parameters by injecting nitrogen gas into a 2-dimensional liquid pool with accumulated solid particles. It was confirmed that under different particle-bed conditions, three representative flow regimes (i.e. the bubble-impulsion dominant, transitional and bed-inertia dominant regimes) are identifiable. Aimed at predicting the regime transitions during sloshing process, a predictive empirical model along with a regime map was proposed on the basis of experiments using single-sized spherical solid particles, and then was extended for covering more complex particle conditions (e.g. non-spherical, mixed-sized and mixed-density spherical particle conditions). To obtain more comprehensive understandings and verify the applicability and reliability of the predictive model under more realistic conditions (e.g. large-scale 3-dimensional condition), further experimental and modeling studies are also being prepared under other more complicated actual conditions.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.446-452
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• 2018

A traffic route is an area associated with high risk for accidents due to the flow of heavy traffic. Despite this concern, most studies related to traffic focus solely on traffic distribution. Therefore, there is a need for studies investigating the characteristics of ships' routes and traffic patterns. In this study, an investigation was carried out to analyze the traffic distribution and pattern in 3 major traffic routes for 3 days. For the purpose of the study, based on the prevailing traffic conditions, the route was divided into 10 gate lines. The ships passing through the lines were also classified into either small, medium and large. ND-K-S (normal distribution, kurtosis, and skewness) test was carried out for the traffic distribution at each gate line based on the information analyzed on each traffic route. The analysis of the results obtained from the ND test showed that large vessels have normal distribution, medium sized vessels have satisfied normal distribution in one-way route only while small sized vessels do not have normal distribution. According to the result obtained from the K-S test, normal traffic pattern shows a significant difference between two-way route and one-way route. Results obtained from the K test result shows that in the case of one-way route, vessels have a traffic pattern using a wide range on traffic route. Further analysis shows that vessels concentrate on one side of route in case of two-way route. Results obtained from the S test show that, in case of one-way route, vessels have a normal traffic pattern according to center line. However, analysis pf the results shows that vessels are shifted to the right side of route in case of two-way route. Despite these findings, it should be noted that this study was carried out in only 3 ports, therefore there is need for investigation to be carried out in various routes and conditions in future studies.

• Journal of Korean Society of Transportation
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• v.30 no.3
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• pp.119-127
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• 2012

For traffic safety, it is imperative for motorists to secure their clear view and to maintain a similar speed with others while driving in a lane. Large-sized vehicles at lower speeds, however, are likely to increase the risk of accident when they share a lane with cars. Although to overcome this complication the Korean Road Traffic Act established rules for the safe use of roads, the reality is that the rules are seldom observed strictly. In this light, this study was designed to analyze the severity of truck-involved accidents, thereby providing justification for the need of truck-designated lanes and thus contributing to measuring road safety more precisely. A binomial logistic regression model was applied to analyze the severity of truck-involved accidents. The analysis showed that several variables affect the severity of truck-involved accidents on freeways; i.e., violation against the rule of truck-designated lanes, weather, difference between daytime and nighttime, and parking on road shoulder. Moreover, the strong enforcement will be needed to make motorists observe the rule, because a Wald statistical test showed that the violation against the rule of truck-designated lanes has the largest influence on the severity.

• Korean Security Journal
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• no.61
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• pp.203-234
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• 2019

The damages from security accidents continue to increase as technology leaks from suppliers cause risks to the management of large companies, which are their customers, and their image and reliability to fall. However, the current industrial structure is practically impossible for large companies to form their own businesses and strategic alliances with business partners are essential, but it is changing into an industrial structure where the exchange of information is increased and the dependence of the information system is maximized, as well as legal demands and demands from stakeholders are increasing due to the complexity of the work process and the strengthening of security-related laws. The status of technology protection of small and medium-sized enterprises shows that they are not equipped with a security system due to relatively poor environment and financial difficulties compared to large enterprises, whereas the industrial structure between large and small business partners is indispensable for sharing the IT system, and the security system of large business, which is a customer company, should be improved by considering the fact that it is impossible to maintain security system between large businesses. Thus, the government intends to examine the system for shared growth of small businesses and the model for evaluating the capabilities of various agencies for information protection, and propose measures to introduce the certification system for small business partners.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.2
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• pp.73-86
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• 2016

The purpose of this study is to examine a security investment for firms experienced in confidential information leak. Information security is an apparatus for protection of secret information. The competence of information security is a competitiveness to avoid information leakage in changing business environment. The type of information security is divided into administrative security, technical security and physical security. It is necessary to improve the incident correspondence competence through information security investment of the three types. Therefore, the investment of information security is to enhance information-asset protection of firms. To reinforce accident response competence, an organization discussed an establishment, security technology development, expand investment and legal system of the security system. I have studied empirically targeting the only information leak of firms. This data is a technical security competence and technology leakage situation of firms happened in 2010. During recovery of the DDos virus damage on countries, company and individual, the collected data signify a reality of information security. The data also identify a security competence of firms worrying information security management. According to the study, the continuous investment of information security has a high competence of accident correspondence. In addition, the most of security accidents showed a copy and stealing of paper and computer files. Firm on appropriate security investment is an accident correspondence competence higher than no security investment regardless of a large, small and medium-sized, and venture firm. Furthermore, the rational security investment should choose the three security type consideration for firm size.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.2
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• pp.97-104
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• 2021

Together with the emerging of the Eco-ship, the application of large-diameter and high-efficiency propeller required more careful attention than before in the design of the shafting system. After the adoption of Environmentally Acceptable Lubricants (EAL) to the stern tube lubrication oil, a number of aft stern tube bearing accidents have been reported, and a variety of institutions have actively conducted research on the cause relationship. This study attempted to find the cause of the accident by measuring the alignment of the shafting system of a medium-sized product/chemical tanker with aft stern tube bearing damage and analyzing the reaction force of each bearing. In addition, a reasonable solution to the correction of the shaft alignment was suggested and the feasibility was reviewed. Through various measured data and analysis, the actual installation of shafting system was slightly different from the design drawing condition, but it was found that each bearing load distribution was within the allowable range. Therefore, it was confirmed that the cause of this accident was due to the dissatisfaction the misalignment slope of aft stern tube bearing rather than the effect of the bearing overload. As a solution to this cause, countermeasures such as double slope were suggested in the aft stern tube bearing, and the characteristics of EAL also seem to have an indirect effect.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.858-862
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• 2018

The purpose of this study is to improve the current vessel departure control regulations to prevent traffic congestion after the lifting of vessel departure controls due to restricted visibility. AIS data was collected to analyze the traffic volume of normal traffic flow and after departure control. A statistical test was conducted to confirm the difference in traffic volume at peak hours according to whether or not departure control was used. The results of the t-test showed that there was a significant difference in traffic volume among groups of less than 10,000 tons in gross tonnage. However, the Mann-Whitney test showed no difference in traffic volume regardless of vessel control. Small and medium-sized vessels of less than 10,000 tons after departure control increased in traffic volume by 142% over normal traffic, and it was concluded that traffic congestion resulted as these small and medium-sized vessels were departing at the same time as large vessels of more than 10,000 tons. In order to prevent vessel collision accidents due to traffic congestion, it is suggested that the navigability of vessels less than 160 m or less than 10,000 tons should be improved.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.2
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• pp.85-94
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• 2016

Lane Designation is defined as reasonable road management to ensure the road safety and enhance road efficiency. While the lane designation system was abolished in 1999, it was redefined because of the increasing number of large vehicles in the passing lane, violent on driving and traffic accidents in 2000. The needs of improvement on operating the lane designation has been increasing more in recent due to the low ratio of compliance with the system and difficulties to keep the right lane due to need of turning and demand of widening of designates lane for two-wheeled vehicles and truck. In this study, we presented the improvement plan through the question survey, simulation analysis, safety evaluation. It found a problem that the low-speed vehicle is to use the upper level roadway, difficulties of supervision, the imbalance in the lane use, imbalance traffic and does not match the international standards. This study suggested five different alternatives through the survey. micro simulation has used in order to examine each alternative by management effectiveness and feasibility. It analyzed the traffic speed, efficiency, traffic balance of alternatives. Also, safety evaluation conducted in terms of the range of field-of-view to ensure the easiness of field of view by various configurational difference between the vehicles. By the analysis results of such indicators, This study presents proposals for improvement in operating designated lane that low-speed-big-sized vehicles keep to the right lane, and high-speed-small sized vehicles keep to the left lane.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.705-713
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• 2018

An automotive ball joint connects the suspension system to the steering system and helps to enable rotational and linear motion between the two elements for steering. This study examines a ball joint used in medium and large-sized pickup trucks. Ball joints consist of a stud, socket, bearing, and plug. The main structural performance metrics of ball joints are the pull-out strength and push-out strength. These structural parameters must meet certain criteria to avoid serious accidents. Test and simulation methods are used to investigate the design requirements, but tests are time-consuming and costly. In this study, we modeled ball joints in SolidWorks and performed a finite element analysis in Abaqus to predict structural performance. The analysis was used to obtain the structural performance required for the static analysis of a 2D axisymmetric model. The uncertainties in the manufacturing of the ball joint were assumed to be the manufacturing tolerances, and the dimensional design variables were identified through case studies. The manufacturing tolerances at each level were defined, and the results were compared with experimental results.