• Korean Security Journal
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• no.22
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• pp.65-90
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• 2010

Recently, alarmed by the frequent international terrorism or safety accidents, the host countries of world sports events are focusing on security activities for the sake of the participants, facilities, events and competitions. They are alarmed because in case any happenings like international terrorism or safety accident, the contest itself can be criticized to be a failure as much as the international reliability of the host nation may well crash. We can see that any failure in coping with terrorism or safety matters can lead to a nation-wise crisis in the case of Indonesia where the October 12th of 2002 terrorist bomb attack in Bali damaged the image of the nation followed by the similar case in Philippine (Oct. 20th, 2002) where the same terrorist attack dramatically scared away the tourists to the nation. Korea is scheduled to hold the World Championship in Athletics in Daegu Metropolitan City in 2011. Also, it is slated to host various world sports events such as Yeosu International Exposition and Incheon Asian Games. In these contexts, this study analyzes counter-terrorism cases related with the recent international sports events that have been organized in a variety of manners in the era of globalization. This study aims to show alternatives for the safety management in these events. In other words, it is focusing on giving directions to the safety policies of the nation -which may become the future hub of north-east Asia and the world - for more perfect guard and defense, and counter-terrorism activities in all the conferences, sports events and international festivals where any private defense and guard companies are allowed to cooperate with the police force or public security agencies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.191-200
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• 2020

Tracked military vehicles are operated under harsher conditions and climates than ordinary vehicles, and the components require high degrees of reliability and durability. A diesel engine is the main power generator, and when the vehicle breaks down, there is a high possibility of causing a large-scale accident. Therefore, analyzing the cause of engine failure can be important for preventing similar cases that may occur. In this study, we clarified the mechanism of engine failure according to an overhaul test, hardness measurement, and an analysis of the fracture surface. The overhaul test confirmed that a bolt was separated from the connecting rod (number 4). In addition, the hardness measurement results of the connecting rod bolt conformed to the standard, and it was found that the bolt fracture was ductile fracture through an analysis of the fracture surface. Based on the results, it was concluded that damage to a diesel engine of a tracked military vehicle was caused by separating and damage caused by loosening of the connecting rod bolts, resulting in cascading damage. The results of the study could be used as reference examples and could be useful for another study on engine failure analysis.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.6
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• pp.50-59
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• 2015

This study aimed at suggesting Willingness To Pay (WTP) for introduction of the Traffic Accident emergency Call (TAC) system by using Contingent Valuation Method (CVM) which is a general valuation method. As the method, this study suggested a WTP estimation method of the TAC system with the double-bound dichotomous choice model. In previous studies, the data are processed differently according to the type of questions and analysis models used for the calculation of willingness to pay. Therefore, we re-organized the model by the cases using the truncated data sets, and showed the difference in WTPs. The dataset was developed by more than 500 questionnaire obtained from online and offline survey with the consideration of composition ratio by age group referring housing census in 2010 to mitigate regional bias of samples. At last, this study applied various statistical methods, survival analysis, multiple regression, and Tobit model for better interpretation of the questionnaires.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.251-261
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• 2019

The importance of autonomous driving systems that utilize V2X services such as V2V(Vehicle to Vehicle) and V2I(Vehicle to Infrastructure) for safer and more comfortable driving is increasing with the recent development of autonomous vehicles. Partly autonomous vehicles based on environmental sensors have limitations for predicting and determining areas beyond the recognition distance of the mounted sensors and in response to atypical objects that are difficult to detect. Therefore, it is important to utilize the V2X service to improve the limit of sensor detection performance and to make driving safer and more comfortable. However, there may be an accident risk of autonomous vehicles due to incorrect information provided by V2X. Thus, the application of technology to prevent this needs to be considered. In this pater, we used the ISO-26262 Part3 Process and performed HARA (Hazard Analysis and Risk Assessment) to derive the risk sources of autonomous vehicles due to V2I malfunctions by using the communication between vehicles and infrastructure among V2X. We also developed ASIL ratings based on the simulations and real vehicle tests of the malfunctions of major cases of usnig V2I.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.2
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• pp.87-92
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• 2019

In this paper, we have verified a low-voltage EM(elasto-magnetic) sensing technique for tensile force management of PSC(prestressed concrete) internal tendon in order to apply the technique to actual construction sites where stable power supply is difficult. From observation of past domestic and overseas PSC structural accident cases, it was found that PS tension is very important to maintain structural stability. In this paper, we have tried to measure the tensile force from a magnetic hysteresis curve through EM sensors according to voltage value by using relation between magnetostriction and stress of ferromagnetic material based on elastic-magnetic theory. For this purpose, EM sensor of double cylindrical coil type was fabricated and tensile force test equipment for PS tendon using hydraulic tensioning device was constructed. The experiment was conducted to confirm relationship between changes of permeability and tensile force from the measurement results of the maximum / minimum voltage amount. The change of magnetic hysteresis curve with magnitude of tensile force was also measured by reducing amount of voltage step by step. As a result, the slope of estimation equation in accordance with magnitude of magnetic field decreases with the voltage reduction. But it was confirmed a similar pattern of change of magnetic permeability for the magnetic hysteresis loop. So, in this study, it is considered that it is possible to manage the tensions of PSC internal tendon using EM sensing technique in low-voltage state.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.32-38
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• 2020

This study examined the problems of existing vehicles to propose alternatives to improve the crashworthiness of railway freight cars through collision acceleration analysis using a one-dimensional collision analysis method. A collision scenario of railway shunting and crash accidents was selected from the collision accident cases and international standards. A one-dimensional collision simulation using LS-DYNA was performed according to those scenarios. As a result, the acceleration level of the freight wagon was calculated to be under 2g and was predicted to meet the EN 12663 standard in the shunting situation. On the other hand, the result of crash simulation with an impact velocity between 10 and 15 km/h revealed the shock absorber capacity of the railway coupler to be insufficient in a crash situation, resulting in increased acceleration, and carbody deformation could be predicted. As a method of improving the crashworthiness, a deformation tube-type energy absorber was applied to the coupler system, and collision analysis was performed again with new energy absorption strategy. Overall, the simulation showed that the acceleration level was decreased by 12% of the conventional freight-car energy absorption system.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.69-76
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• 2008

Three failure cases of CNG composite vessels were reported since after January 2005. The 1st and 2nd accidents were indebted to vessel defect and installation mistake. The 3rd was caused by gas leak at pipe connections. In this paper various aspects were studied based on information of the three failure analysis, which must be improved for better safety of the CNG bus system. Overpressure region caused by vessel explosion was theoretically predicted and also assessed by PHAST program. Explosion of 120 l vessel under 20 MPa is equivalent to 1.2 kg TNT explosion. The predicted value by PHAST was more serious than theoretical one. However, actual consequence of explosion was much less than both of the predicted consequences. Since the CNG vessel was designed by the performance based design methodology, it is difficult to verify whether the required process and tests were properly conducted or not after production. If material toughness is not enough, the vessel should be weak in brittle fracture at early in the morning of winter season since the metal temperature can be lower than the transition temperature. If autofrettage pressure is not correct, fatigue failure due to tensile stress during repeated charging is possible. One positive aspect is that fire did not ocurred after vessel failure. This may be indebted to fast diffusion of natural gas which hindered starting fire.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.338-347
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• 2023

Jinhae Bay, characterized by frequent runaway ships and strong winds during typhoon attacks, poses a high risk of maritime accidents such as ship collisions and groundings. This study aims to determine a safe separation distance between ships in the Jinhae Bay anchorage, considering the unique environmental characteristics of the Korean sea area. Analysis revealed that an average of 100-200 ships anchor in the typhoon avoidance area in Jinhae Bay during typhoon attacks, with approximately 70% of ships experiencing anchor dragging owing to strong external forces exceeding 25 m/s wind speeds. In this study, we analyzed and presented the separation distances between ships during anchoring operations based on domestic and international design standards, separation distances between ships used as actual typhoon shelters in Jinhae Bay, and appropriate safe distances for ships drifting under strong external forces. The analysis indicated that considering the minimum criteria based on the design standards and emergency response time, a minimum safe distance of approximately 400-900 m was required. In cases where ample space was available, the separation distance was recommended to be set between 700 to 900 m. The findings of this study are anticipated to contribute to the development of guidelines for establishing safe separation distances between ships seeking refuge from typhoons in Jinhae Bay in the future.

• Journal of Chest Surgery
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• v.45 no.1
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• pp.24-29
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• 2012

Background: The conventional method of aortic cross-clamping is very difficult and increases the risk of cerebral infarct due to embolism of the calcified aorta in these patients. Accordingly, we analyzed our experience with 11 cases of ascending aorta and aortic valve replacement with hypothermic circulatory arrest. Materials and Methods: From January 2002 to December 2009, 11 patients had ascending aorta and aortic valve replacement with hypothermic arrest at our hospital. We performed a retrospective study. Results: There were 5 males and 6 females, with a mean age of 68 years (range, 44 to 82 years). Eight patients had aortic stenosis, and 3 patients had aortic regurgitation. An aortic cannula was inserted into the right axillary artery in 3 patients and ascending aorta in 6 patients. Two patients with aortic regurgitation had a remote access perfusion catheter inserted though the right femoral artery. The mean cardiopulmonary bypass time was 180 minutes (range, 110 to 306 minutes) and mean hypothermic circulatory arrest time was 30 minutes (range, 20 to 48 minutes). The mean rectal temperature during hypothermic circulatory arrest was $21^{\circ}C$ (range, $19^{\circ}C$ to $23^{\circ}C$). No patient had any new onset of cerebral infarct or cardiovascular accident after surgery. There was no hospital mortality. Early complications occurred in 1 patient who needed reoperation due to postoperative bleeding. Late complications occurred in 1 patient who underwent a Bentall operation due to prosthetic valve endocarditis. The mean follow-up duration was 32 months (range, 1 month to 8 years) and 1 patient died suddenly due to unknown causes after 5 years. Conclusion: Patients with a calcified aorta can be safely treated with a technique based on aorta and aortic valve replacement under hypothermic circulatory arrest.

• The Journal of the Korea Contents Association
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• v.14 no.3
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• pp.186-194
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• 2014

The purpose of this paper is to review the meaning of extended application of workers' compensation for artists. This study explains by giving specific two examples. The first case is about broadcasting extra who is permitted to receive compensation from Korea Workers' Compensation & Welfare Service without filing a suit. Whereas, The second case is about musical stage crew who is not permitted to obtain compensation for accident during work. The reason why he could not receive compensation is not because he is regarded as worker, but because he is regarded as individual businessman. Extended application of workers' compensation for artists could be a double-edged sword for workers through two cases. Firstly, Broadcasting extras could become much easier to receive workers' compensation according to precedent. Secondly, It is more difficult to get the workers' compensation by the reason of not applying for workers' compensation admission like the second case, even though the second case of forms of employment is similar to that of the first. In other words, New compensation development could generate another obstacles to enter compensation systems. Extended application of workers' compensation should be operated with covering artists' compensation case by case.