• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.5
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• pp.1554-1566
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• 2014

Cloud Computing allows application providers seamlessly scaling their services and enables users scaling their usage according to their needs. In this paper, using queuing game model, we present service scheduling schemes which are used in software as a service (SaaS). The object is maximizing the Cloud Computing platform's (CCP's) payoff via controlling the service requests whether to join or balk, and controlling the value of CCP's admission fee. Firstly, we treat the CCP as one virtual machine (VM) and analyze the optimal queue length with a fixed admission fee distribution. If the position number of a new service request is bigger than the optimal queue length, it balks. Otherwise, it joins in. Under this scheme, the CCP's payoff can be maximized. Secondly, we extend this achievement to the multiple VMs situation. A big difference between single VM and multiple VMs is that the latter one needs to decide which VM the service requests turn to for service. We use a corresponding algorithm solve it. Simulation results demonstrate the good performance of our schemes.

• Nuclear Engineering and Technology
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• v.35 no.1
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• pp.80-90
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• 2003

According to related studies, it was revealed that the procedural deviation plays a significant role in initiating accidents or incidents. This means that, to maximize safety, it is indispensable to be able to answer the question of “why the operators deviate from procedures\ulcorner” In this study, the SC (step complexity) measure is introduced to investigate its applicability for studying the procedural deviation, since it was shown that the change of the operators' performance is strongly correlated with the change of SC scores. This means that the SC measure could play an important role for researches related to the procedural deviation, since it is strongly believed that complicated procedures would affect both the operator' performance and the possibility of the procedural deviation. Thus, to ensure this expectation, the meaning of the SC measure is investigated through brief explanations including the necessity, theoretical basis and verification activities of the SC measure. As a result, it is confirmed that the SC measure can be used to explain the change of the operators' performance due to the task complexity implied by procedures. In addition, it seems that the SC measure nay be useful for various purposes, particularly for scrutinizing the relationship between the procedural deviation and complicated procedures.

• Journal of Aerospace System Engineering
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• v.8 no.3
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• pp.34-40
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• 2014

Since the global economic crisis in year 2008, the world civil helicopter market has been growing recently. According to the market outlook in the next decade, the demand of civil helicopter will be driven by the demand of Private & Corporate, Oil & Gas, Off-shore and EMS(Emergency Medical Service) usages. On the other side, the demand of military market will be driven by the modification and upgrading for life extension or performance enhancement than the new helicopter development for replacing old models. To summarize these situations, the demand of MRO(Maintenance, Repair & Overhaul) market has also been on the rise because of the demand due to above several usages in civil side and the life-extension in military side. Through the MRO market analysis for characteristics, developmental trends and a supply chain, this paper describes that the potential of MRO business is considerably large as a propulsive power of domestic helicopter industry. And also, it proposes the construction direction of MRO network because the domestic industry must make the developmental awareness and reliability a stepping-stone towards own helicopter.

• Fire Science and Engineering
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• v.25 no.6
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• pp.178-183
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• 2011

In cold season, the elevator systems in super high-rise buildings would make noises at the door-gaps on high floors, and the elevator doors on the 1st floor would suffer from opening/closing trouble due to the pressure differences. Such pressure differences are also the main driving power of smokes through the hoistway in the case of fire. In addition, the pressure differences should be overcome to use the elevator systems as a measure of emergency escape. This paper reviews the way of hoistway pressurization to reduce the adverse influences. Simulations achieved a good result close to the requirements of NFPA 92A and IBC 2012 under the condition that the hoistway should be pressurized after pressure equalizing between floors and hoistway with the openings through the hoistway wall.

• Fire Science and Engineering
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• v.33 no.4
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• pp.130-139
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• 2019

The electronics factory fire, that occurred at 15:40 on August 21, 2018, killed nine people and injured six. This study analyzes the causes of many of the casualties from the fire, and is based on fire investigation results and so on. The findings suggest that major causes included failure of the automatic alarm system to function, failure of the emergency broadcasting system to function, the fire suddenly spreading due to polyurethane foam in a ceiling on the 4thfloor, a power outage immediately after the fire started, a sprinkler system that was not working, a delay in reporting the fire, and improper management of fire facilities by a fire safety management company.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.3
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• pp.69-77
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• 2006

This paper presents the service restoration in electric power distribution systems. The aim of the service restoration is to control an emergency taken place in distribution systems and to restore out-of service areas as soon as possible when a fault occurs in distribution systems. For this reason, new service restoration strategies in multi-outage area are suggested in this paper. The suggested algorithm consist of two schemes. One is an individual restoration scheme, the other is an integrated restoration scheme. The former determines a restoration order of outage areas based on a restoration index. Unless the former scheme can generate a feasible restoration plan, the latter one will try to find out a new configuration without an overloaded section through tie exchange method.

• International Journal of Railway
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• v.3 no.2
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• pp.54-59
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• 2010

In order to develop the deep-underground GTX (Great Train eXpress) in domestic, the running performance analysis of the propulsion system by a variety of route condition must be carried out before studying the specification and the development of the high-speed propulsion system with inverter and traction motor. Then it is necessary to study the running resistance properties of the high-speed traction system for the variety of tunnel type and vehicle organization method at first. In addition, the properties of the power requirement of the traction motors needed to maintain the balanced speed of the high-speed traction system are next studied. We need to study properties of the emergency braking distance caused by the highest operation speed of the high-speed traction system and present the fundamental design technologies to develop the high-speed traction system for the deep-underground GTX. Finally, the paper analyzes the applicability of the conventional Korean Tilting Train eXpress (TTX) propulsion system on the high-speed propulsion system for the deep-underground GTX.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.87-95
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• 2011

The urgent VAI(Vital Area Identification) method development is required since 'The Act of Physical Protection and Radiological Emergency' that is established in 2003 requires an evaluation of physical threats in nuclear facilities and an establishment of physical protection in Korea. The KAERI(Korea Atomic Energy Research Institute) has developed the VAI methodology and VAI software called as VIPEX(Vital area Identification Package EXpert) for identifying the vital areas. This study is to demonstrate the applicability of KAERI's VAI methodology to a hypothetical facility, and to identify the importance of information of cable and piping runs when identifying the vital areas. It is necessarily needed to consider cable and piping runs to determine the accurate and realistic TEPS(Top Event Prevention Set). If the information of cable and piping runs of a nuclear power plant is not considered when determining the TEPSs, it is absolutely impossible to acquire the complete TEPSs, and the results could be distorted by missing it. The VIPEX and FTREX(Fault Tree Reliability Evaluation eXpert) properly calculate MCSs and TEPSs using the fault tree model, and provide the most cost-effective method to save the VAI and physical protection costs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.525-526
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• 2007

Continuous on-line temperature monitoring provides the means to evaluate current condition of equipment and detect abnormality. It allows corrective measures to be taken to prevent upcoming failure. Continuous temperature monitoring and event recording provides information on the energized equipment's response to normal and emergency conditions. On-line temperature monitoring helps to coordinate equipment specifications and ratings, determine the real limits of the monitored equipment and optimize facility operations. Using wireless technique eliminates any need for special cables and wires with lower installation costs if compared to other types of online condition monitoring equipment. In addition, wireless temperature monitoring works well under difficult conditions in strategically important locations. Wireless technology for on-line condition monitoring of energized equipment is applicable both as standalone system and with an interface with power quality monitoring system.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.603-609
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• 2020

The purpose of this study is to research dampers, which are applied mainly to buildings adjacent to the coast, such as nuclear facilities, and used for ventilation and can safely protect lives and equipment in emergency situations. Comparing the equivalent stress for three models with hinge reinforcement and support reinforcement based on the early design model for Damper, in the Base model, the highest stress occurred in the part of hinge, especially in the centrally mounted hinge, and after reinforced the hinge, it was occurred in the rear support. For models reinforced hinges and supports, it is considered that reinforcement for stiffness will be required in the future as it entered within the range of allowable stress. For the safety factor distribution, the minimum safety ratio was sufficiently secured at least 1 and was high at the edge of the Damper frame and the Blade. As the hinge was reinforced, the safety factor distribution of Blade was increased, and it was verified that the safety factor was secured through the support reinforcement.