• Journal of Information Technology Applications and Management
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• v.30 no.6
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• pp.17-29
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• 2023

In this paper, we aim to propose cyber security considerations and countermeasures for infrastructure and services in the UAM(Urban Air Mobility) Air Traffic Management field, which is one of the key elements of the UAM market that has not yet bloomed. Air traffic management is an important factor for safe navigation and social acceptance of UAM. In order to realize air traffic management, infrastructure and services based on solid network connectivity must be established. And for industries where connectivity is the core component, it can become an infiltration route for cyber threats. Therefore, cyber security is essential for the infrastructure and services. In detail, we will look into the definition of the existing air traffic management field and the cyber threats. In addition, we intend to identify cyber security threat scenarios that may occur in the newly designed UAM air traffic management infrastructure. Moreover, in order to study the cyber security countermeasures of the UAM air traffic management infrastructure, there will be analysis of the UAM operation concept. As a result, countermeasures applicable to the infrastructure and service fields will be suggested by referring to the cyber security frameworks.

• ETRI Journal
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• v.24 no.1
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• pp.43-55
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• 2002

This paper proposes a flow-based admission control algorithm through an Asynchronous Transfer Mode (ATM) based Multi-Protocol Label Switching (MPLS) network for multiple service class environments of Integrated Service (IntServ) and Differentiated Service (DiffServ). We propose the Integrated Packet Scheduler to accommodate IntServ and Best Effort traffic through the DiffServ-aware MPLS core network. The numerical results of the proposed algorithm achieve reliable delay-bounded Quality of Service (QoS) performance and reduce the blocking probability of high priority service in the DiffServ model. We show the performance behaviors of IntServ traffic negotiated by end users when their packets are delivered through the DiffServ-aware MPLS core network. We also show that ATM shortcut connections are well tuned with guaranteed QoS service. We validate the proposed method by numerical analysis of its performance in such areas as throughput, end-to-end delay and path utilization.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.58-65
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• 2001

Many changes in the railway environment has directly affected to the railway company. To cope immediately with the influence of environment and to promote productivity, the railway company has to introduce an efficient train operation system and related core technologies. The railway system is composed or large-scale infrastructures ann high-cost trains. Simulation method is one or core technologies and also is efficient tool for planning and analyzing this kind of complex system. The purpose of this research is to develop multi-train traffic simulator considering high-speed train for GyongBu-Line. To achieve this objective, the elements of railway system was analyzed, and as a result, a data structure modeling for the railway system such as rail-Tine infrastructure, rain, timetable and operational route is presented. The developed simulator is composed of three major part : input-module, main-module, and output module. The concept and brief explanation of each module will be treated.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.759-762
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• 2012

This paper is for EPC(Evolved Packet Core) network to share the load balance by IMSI(International Mobile Subscriber Identity) prefix in MME(Mobility Management Entity). For the telecommunication, it needs to choose the anchoring gateway to use the specific gateway to avoid the traffic load to support the efficient telecommunication service. We propose the way to choose the effective gateway to avoid the traffic load in order for good qualify service. We compare the load between the gateways which are the general gateway and the specific gateway used by proposed concept.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.4
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• pp.678-691
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• 2015

Internet and mobile traffic continues to surge exponentially in recent years due to popularization of smart devices, the appearance of various internet services carrying large amount of traffic from richer content and applications. This phenomenon leaded to various network problems such as the congestion delay, the non-balanced traffic ratio between ISPs, the continuous network investment cost and the Internet access problems. In light of changed data-driven communication ecosystem, There are growing concerns by both academia and industry that settlement-free peering and full transit regime have the limitations such as not only difficulties in maintaining mutual benefits but also difficulties in securing investment incentives for upgrading network performance and quality. Thus, it becomes more necessary for introducing the evolved internet interconnection regime which can fulfill the All-IP network environment. This study derives core issues regarding internet interconnection regime in Korea and suggest new evolved alternatives based on three point of view(traffic optimization, cost optimization, network investment optimization) through the empirical analysis.

• Journal of Power System Engineering
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• v.21 no.3
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• pp.85-92
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• 2017

Global air traffic is forecast to grow at an average annual rate of around 5% in the next 20 years. The continuous growth of air traffic and raised environmental awareness put increasing pressure on aero engine manufacturers to reduce fuel burn and emissions. NEWAC are a new integrated program of the European Union with focus on innovative core engine concepts to achieve this problem. In this paper, Within NEWAC, active core engine configurations will be investigated. the investigation is focused on the optimal design of the CAC heat exchanger for active core. For optimal design of he CAC heat exchanger, the HTFS of basic design of heat exchanger are analyzed so as to proceed an optimization routines based on Response Surface Method(RSM) and Design of Experiment(DOE). As a result, CAC heat exchanger optimized by 1.0314 lb/s mass flow rate and 3.9058 mm TP of tube layout and 206.8181 mm height of heat exchanger and 918 tube number for heat transfer and pressure drop. We confirm the design optimization using RSM and DOE is useful on complex structure of heat exchanger.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.32-38
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• 2015

In this paper, we propose a smallcell local caching algorithm under user's context in smallcell environment. The proposed system reduces traffic to core network and the network cost, but increases it's performance. The proposed algorithm precache suitable files using smallcell's regional characteristics and target's personality. It can adjusts a storage allocation to make effective usage of our limited cache storage capacity. In order to evaluate the performance of the proposed cache algorithm, we define the cache efficiency, the decrement of core network traffic. The simulation results show that the proposed algorithm can improve performance by about 200% compared to existing web cache scheme.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.94-99
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• 2012

Due to economic growth, the number of cars has grown rapidly and consequently traffic accidents have grown in direct ratio. This reminds us that braking device of a vehicle is an important factor to prevent traffic accidents. Aim these researches to speed and lighten the braking system of vehicles, to lengthen its durability and to shorten the stopping distance. However, it is still difficult to analyze quantitatively and clearly the reason and solution for abnormal wear of disc and pad or judder in flywheel mode. Therefore this study was carried out to presume for mutual relation of analysis condition to get the optimum temperature by two-way layout. The results shown that coefficient of determination has a fine reliability over 92.57% and temperature is made by two-way layout.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.3
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• pp.257-263
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• 2013

The classification of risk factors and the identification of risk acceptance criteria are core works to assess risk levels with high enough confidential level in the field of marine traffic environment. In the previous study work, the twenty kinds of risk factors and its assessment criteria for the domestic marine traffic environment were proposed. In this paper, with these previous studying results, the relative importance of the risk factors were analyzed by questionnaire survey of marine traffic experts using the analytic hierarchy process. The analysis results showed that the relative importance of the visibility restriction is the highest among the twenty kinds of risk factors, and the relative importance of the traffic condition is the highest among the five kinds of risk categories. As results from analysis, it is expected that the approaching method on the relative importance is to be one of basic techniques for the development of risk assessment models in the domestic marine traffic environment.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.126-135
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• 2014

This paper describes the development and verification of control algorithms for V2X and environmental sensor integrated intersection support and safety systems. The objective of the research is to develop core technologies for effective fusion of V2X and environmental sensors and to develop new safety function for intersection safety. One of core technologies is to achieve the improvement of GPS accuracy, and the other is to develop the algorithm of a vehicle identification which matches all data from V2X, vehicle sensors and environmental sensors to specific vehicles. A intersection optimal pass (IOP) algorithm is designed based on these core technologies. IOP recommends appropriate speed to pass the intersection in the consideration of traffic light signal and preceeding vehicle existence. Another function is developed to prevent a collision avoidance when car crash caused by traffic violation of surrounding vehicles is expected. Finally all functions are implemented and tested in three test vehicles. It is shown that IOP can support convenient and comfortable driving with recommending optimal pass speed and collision avoidance algorithm can effectively prevent collision caused by traffic sign violation of surrounding vehicles.