• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.3
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• pp.257-264
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• 2017

For the safe disposal of intermediate level radioactive waste according to the Nuclear Safety and Security Commission's notice and KORAD's management plan for low and intermediate level radioactive waste, the disposal concentration limit was derived based on the IAEA methodology. The evaluation of the derived disposal concentration limit revealed that it is not suitable as a practical limit for intermediate level radioactive waste. This is because the disposal concentration limit according to the IAEA methodology is derived using a single value of radioactive waste density and the disposal facility's volume. The IAEA methodology is suitable for setting the concentration limit for vault type disposal, which consists of a single type of waste, whereas an underground silo type disposal facility is composed of several types of radioactive waste, and thus the IAEA methodology has limitations in determining the disposal concentration limit. It is necessary to develop and apply an improved method to derive the disposal concentration limit for intermediate level radioactive waste by considering the radioactivity of various types of radioactive waste, the corresponding scenario evaluation results, and the regulatory limit.

• Journal of the Korean Institute of Gas
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• v.14 no.6
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• pp.15-20
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• 2010

Compressed Natural Gas (CNG) buses have been supplied since the year 2000 in order to resolve severe atmospheric pollution in metropolitan area and contributed on the improvement of urban atmospheric environment. However, it is indispensible to take an adequate measure to guarantee the safety of CNG vehicles because of the possibility of huge fire accident. A receptacle, connecting device between high pressure fuel supply tank and fuel line, plays an important role in CNG supply system. In recent, leakage of CNG from receptacles has been reported. So, the concern about the security and reliability of receptacles has been arisen. Therefore, a lot of efforts to prevent leakage are invested among researchers and the durability of this component should be guaranteed despite repeated operation. This research has performed durability tests of a CNG receptacle regarding the repeated usage, extreme chattering, and continuous full flow test. Although a receptacle used for CNG vehicle satisfies validation requirements in the test results, it has been found that failure in the function of leakage prevention in a receptacle could take place in the case of prolonged exposure to high supply pressure in common quick charging environment on site.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.125-136
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• 2018

Heavy snowfall disasters are the third most serious natural disasters, after typhoon and heavy rainfall disasters, in terms of economic disaster damage in South Korea. The average annual economic damage of heavy snowfall disasters was approximately eighty-eight billion won during the period of 2005-2014. In spite of significant economic damage, there have been few economic studies regarding heavy snowfall disasters in South Korea. The objective of this research is to identify the association between economic damage of heavy snowfall disasters and damage effect factors of snowfall amounts, snowfall days, population densities, and non-urban area ratios using a regression analysis model. Economic damage data sets of heavy snowfall disasters during the period of 2005-2014 were obtained from the Natural Disaster Yearbook published by the Ministry of Public Safety and Security. Weather-related data sets, such as snowfall amounts and snowfall days were collected from the Korea Meteorological Administration. Demographic and urban data sets, including population densities and non-urban area ratios, were provided by the Local Government Yearbook. Outcomes of this study can assist with heavy snowfall disaster management policies of South Korea.

• Journal of the Korea Institute of Building Construction
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• v.16 no.6
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• pp.519-527
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• 2016

The demand of construction risk analysis is rapidly increased to improve the competitiveness of construction companies and the sound management of the construction project. However, estimating the amount and uncertainty of the risk is difficult due to the wide range of risks in the construction industry. Moreover, most of the research on risk management of construction risk is only focused on the causes of risk without separate the internal and external risk. This study statistically analysis the internal risk and external risk based on the accidents cases which are caused at construction sites to define the difference and importances of the risk. An accident cause analysis and T-test analysis are carried out to reach the goal of study. The results of the study are expected to be used as a guideline of construction project risk analysis.

• Journal of the Korean Data and Information Science Society
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• v.22 no.6
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• pp.1153-1166
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• 2011

Detecting misbehavior in vehicular ad-hoc networks is very important problem with wide range of implications including safety related and congestion avoidance applications. Most misbehavior detection schemes are concerned with detection of malicious nodes. In most situations, vehicles would send wrong information because of selfish reasons of their owners. Because of rational behavior, it is more important to detect false information than to identify misbehaving nodes. In this paper, we propose the variable precision rough sets based misbehavior detection scheme which detects false alert message and misbehaving nodes by observing their action after sending out the alert messages. In the proposed scheme, the alert information system, alert profile is constructed from valid actions of moving nodes in vehicular ad-hoc networks. Once a moving vehicle receives an alert message from another vehicle, it finds out the alert type from the alert message. When the vehicle later receives a beacon from alert raised vehicle after an elapse of time, then it computes the relative classification error by using variable precision rough sets from the alert information system. If the relative classification error is lager than the maximum allowable relative classification error of the alert type, the vehicle decides the message as false alert message. Th performance of the proposed scheme is evaluated as two metrics: correct ratio and incorrect ratio through a simulation.

• Journal of Wetlands Research
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• v.23 no.1
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• pp.27-34
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• 2021

In this study, the main influencing factors of the occurrence of cyanobacteria at each of the eight Multifunctional weirs were derived using a random forest, and a categorical prediction model based on a Algal bloom warning system was developed. As a result of examining the importance of variables in the random forest, it was found that the upstream points were directly affected by weir operation during the occurrence of cyanobacteria. This means that cyanobacteria can be managed through efficient security management. DO and E.C were indicated as major influencers in midstream. The midstream section is a section where large-scale industrial complexes such as Gumi and Gimcheon are concentrated as well as the emissions of basic environmental facilities have a great influence. During the period of heatwave and drought, E.C increases along with the discharge of environmental facilities discharged from the basin, which promotes the outbreak of cyanobacteria. Those monitoring sites located in the middle and lower streams are areas that are most affected by heat waves and droughts, and therefore require preemptive management in preparation for the outbreak of cyanobacteria caused by drought in summer. Through this study, the characteristics of cyanobacteria at each point were analyzed. It can provide basic data for policy decision-making for customized cyanobacteria management.

• Journal of Space Technology and Applications
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• v.2 no.2
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• pp.146-168
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• 2022

Witnessing current military conflicts in South China Sea and Eastern Europe, most defense analysts evaluate one of the most serious security threat toward the US is coming from the superpower competitions with Russia and China. The main means for such super power hegemonic competitions is military power and space power is a key enabler to maximize the efficiency and effectiveness of military employment. Reflecting above circumstances, the space hegemonic competition between the Unites States and China is spreading into all aspects of national powers. Under such an environment, R.O.K needs to significantly develop national space power to preserve life and assets of people in space. On the other hand, the R.O.K has a lot of limitations in launching space assets into orbits by land-based space rockets due to its geographic locations. The limitation of rocket launching direction, the failure to secure a significant area enough to secure safety and the limitation to secure open area enough to build associated facilities are among them. On this paper, I will suggest the need to build the 2nd space rocket launching site after analyzing a lot of short-falls the current 'Naro' space center face, compared to those of advanced space powers around the world.

• Journal of Navigation and Port Research
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• v.47 no.1
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• pp.10-17
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• 2023

A series of studies on the development of autonomous surface ships have been promoted in domestic and foreign countries. One of the main technologies for the development of autonomous ships is path-following control, which is closely related to securing the safety of ships at sea. In this regard, the path-following performance of an autonomous ship should be first evaluated at the design stage. The main aim of this study was to develop a visual and quantitative evaluation method for the path-following control performance of an autonomous ship at the design stage. This evaluation technique was developed using a computational fluid dynamics (CFD)-based path-following control model together with a line-of-sight (LOS) guidance algorithm. CFD software was utilized to visualize waves around the ship, performing path-following control for visual evaluation. In addition, a quantitative evaluation was carried out using the difference between the desired and estimated yaw angles, as well as the distance difference between the planned and estimated trajectories. The results demonstrated that the ship experienced large deviations from the planned path near the waypoints while changing its course. It was also found that the fluid phenomena around the ship could be easily identified by visualizing the flow generated by the ship. It is expected that the evaluation method proposed in this study will contribute to the visual and quantitative evaluation of the path-following performance of autonomous ships at the design stage.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.899-910
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• 2023

The majority of research on lifestyle has been conducted based on a variable-centered approach. However, over the last decades, there is a growing body of research on lifestyle in terms of a person-centered approach. Hence, this study identifies senior generations' profiles based on the combination of the five realms of lifestyle. More specifically, this study utilized a Latent profile analysis(LPA) to explore both quantitatively and qualitatively distinct types of senior generation' lifestyle profiles. As a result, the five distinct types of senior lifestyle profiles were identified and these five profiles were then contrasted with traveling attitude and behavioral intention(traveling intention). In addition, this study attempted to identify similarity in the patterns of relations with theoretical antecedent, correlate and outcome variables. Results showed that even though senior generation belonging to profile groups pertaining to the high level of all five types of lifestyle were associated with a high level of attitude and behavior intention, there was no differences among the profiles. This means that regardless of the patterns of senor generation lifestyle profiles, there was no similarity. Nevertheless, it should be considered that senior generation consider a security when making a travel ling decision regardless of the patterns of lifestyle profiles. This results suggest that senior generation' traveling satisfaction is more likely obtained with the experience of safety and convenience during their travel. At last, this study discusses some implication tourism theory related to lifestyle, practices and future research on tourism profiles.

• Journal of the Korea Convergence Society
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• v.5 no.4
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• pp.113-119
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• 2014

Fire fighters should eat their meal very fast in order to arrive in the emergency scene on time. The purpose of the study is to investigate the influence of eating speed on the health of the fire fighters. The subjects were fire fighters, National maritime police, soldiers, public officials, university students, and company employees. The fire fighters had the shortest eating time of 8 minutes 29 seconds, and eating speed of National maritime police was 8 minutes 33.17 seconds, and public officials had 12 minutes 49.33 seconds. Soldiers had 10 minutes 15 seconds, university students had 14 minutes 15 seconds, and company employees had 16 minutes 51 seconds in eating their meals. The previous studies said that eating speed had influenced on the metabolic syndrome and the survey on the American fire fighters showed that the fire fighters gained 7.7 pounds during the past 8 years. Through this study, it is necessary to implement the right eating habit that is able to slow down the eating speed in the Korean fire fighters. The Fire Academy should provide the right eating habit education program to the fire fighters.