• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 한국추진공학회 2008년 영문 학술대회
• /
• pp.330-339
• /
• 2008

Ground-based interceptors(GBI) comprise a major element of the strategic defense against hostile targets like Intercontinental Ballistic Missiles(ICBM) and reentry vehicles(RV) dispersed from them. An optimum design of the subsystems is required to increase the performance and reliability of these GBI. Propulsion subsystem design and optimization is the motivation for this effort. This paper describes an effort in which an entire GBI missile system, including a multi-stage solid rocket booster, is considered simultaneously in a Genetic Algorithm(GA) performance optimization process. Single goal, constrained optimization is performed. For specified payload and miss distance, time of flight, the most important component in the optimization process is the booster, for its takeoff weight, time of flight, or a combination of the two. The GBI is assumed to be a multistage missile that uses target location data provided by two ground based RF radar sensors and two low earth orbit(LEO) IR sensors. 3Dimensional model is developed for a multistage target with a boost phase acceleration profile that depends on total mass, propellant mass and the specific impulse in the gravity field. The monostatic radar cross section (RCS) data of a three stage ICBM is used. For preliminary design, GBI is assumed to have a fixed initial position from the target launch point and zero launch delay. GBI carries the Kill Vehicle(KV) to an optimal position in space to allow it to complete the intercept. The objective is to design and optimize the propulsion system for the GBI that will fulfill mission requirements and objectives. The KV weight and volume requirements are specified in the problem definition before the optimization is computed. We have considered only continuous design variables, while considering discrete variables as input. Though the number of stages should also be one of the design variables, however, in this paper it is fixed as three. The elite solution from GA is passed on to(Sequential Quadratic Programming) SQP as near optimal guess. The SQP then performs local convergence to identify the minimum mass of the GBI. The performance of the three staged GBI is validated using a ballistic missile intercept scenario modeled in Matlab/SIMULINK.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• 제28권6호
• /
• pp.1509-1522
• /
• 2018

The purpose of this study is to support flexible authentication functions in various services using various types of user information. Rather than requiring the same level of authentication for all services, the goal is to identify the level of authentication at the time of user authentication and to increase convenience and efficiency by dynamically granting authority. In this paper, we propose POSCAL (Protocol of Service Control by Authentication Level) protocol which can control service access based on various local authentication information. To verify the function of the authentication framework, we developed the electronic wallet service based on the POSCAL authentication framework and evaluated the implementation function based on the use case scenario. The proposed protocol satisfies user and message authentication, confidentiality of authentication information, integrity of authentication history, non - repudiation of authorization, and access control by service according to security level.

• Journal of Korea Entertainment Industry Association
• /
• 제14권7호
• /
• pp.421-427
• /
• 2020

The aim of this study was to examine the impacts of pre-briefing using structured video simulations in the pre-hospital trauma care simulation-based education on simulation immersion, simulation confidence, and simulation satisfaction. For both the experimental group and the control group, orientations were conducted on the simulation environment. Subsequently, the experimental group watched a video of about 8 minutes, similar to the scenario situation, in which the goal and result of the training were presented. The control group, on the other hand, conducted a classical way of orientation related to the scenario during the same time period. In addition, the experimental group and the control group underwent simulation practice in the same situation for 12 minutes, and debriefing was performed for 40 minutes by the same research assistant. Afterwards, we measured the simulation immersion, confidence, and satisfaction of the participants. Data were analyzed using χ² and independent t-test using the SPSS 22.0 program. It was found that the experimental group that conducted the pre-briefing using video had higher immersion and confidence than the control group. On the other hand, satisfaction was not significantly different between the two groups. The results indicate that pre-briefing using structured video was an effective educational method to increase simulation immersion and simulation confidence.

• Proceedings of the Korea Society for Simulation Conference
• /
• 한국시뮬레이션학회 2001년도 The Seoul International Simulation Conference
• /
• pp.231-236
• /
• 2001

Virtual Reality (VR) is a new technology that enables humans to communicate with a computer, It allows the user to see, hear, fuel and interact in a three-dimensional virtual world created graphically. Virtual Reality Therapy (VRT), based on this sophisticated technology, has been recently used in the treatment of subjects diagnosed with acrophobia. Acrophobia is a disorder that is characterized by marked anxiety upon exposure to heights, avoidance of heights, and a resulting impairment in functioning. Conventional virtual reality systems for the treatment of acrophobia have limitations, such as overly expensive devices or somewhat unrealistic graphic scenes. The goal of this study is to develop an inexpensive and more realistic virtual environment in which to perform an exposure therapy fur acrophobia. It runs on a personal computer, and a virtual scene ova bunge-jump tower in the middle of a large city. The virtual scenario includes an open tin surrounded by props beside a tower, which allows the patient to feel a sense of heights. The effectiveness of the VR environment was evaluated through the clinical treatment of a subject who was suffering from the fear of heights. Based on pre- and post- questionnaires and subjective comments from the subject. This virtual reality environment proved to be an effective and realistic tool fur the treatment of acrophobia.

• Proceedings of the CALSEC Conference
• /
• 한국전자거래학회 1999년도 학술대회지 vol.2
• /
• pp.587-596
• /
• 1999

In this paper, we introduce the design and development of a web-based workflow management system. The goal of the developed system is to manage business processes occurring in the CITIS (Contractor Integrated Technical Information Services) environment. The system is composed of three main modules: Process Designer, Workflow Engine, and Client modules. The Process Designer is a module that provides the environment for the build-time function, which generates the specifications of processes. The module presents the capability of defining nested process models, which is powerful in particular for designing complex processes. Since the other two modules are implemented using pure Java technology, the Workflow Engine can be implemented on any platform and the Client programs can be accessed via the WWW interface. This indicates that there is no need to install any client programs at the client-sides. Users who has a connection to the internet with web browsers, such as Internet Explorer and Netscape Navigator, and has a proper right of access can utilize the normal client, monitoring client, and system administration client programs. Communications between the workflow engine and the clients are implemented using the java servlet mechanism. The workflow system can serve as the underlying platform of process management tool in CALS and CITIS environments. An example scenario of using the system is presented.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제5권9호
• /
• pp.1513-1527
• /
• 2011

This paper investigates the capacity rate problems for a joint decode-and-forward (JDF) based two-way relaying with network coding. We first characterize the achievable rate region for a conventional three-node network scenario along with the calculation of the corresponding maximal sum-rate. Then, for the goal of maximizing the system sum-rate, opportunistic relay selection is examined for multi-relay networks. As a result, a novel strategy for the implementation of relay selection is proposed, which depends on the instantaneous channel state and allows a single best relay to help the two-way information exchange. The JDF scheme and the scheme using relay selection are analyzed in terms of outage probability, after which the corresponding exact expressions are developed over Rayleigh fading channels. For the purpose of comparison, outage probabilities of the amplify-and-forward (AF) scheme and those of the scheme using relay selection are also derived. Finally, simulation experiments are done and performance comparisons are conducted. The results verify that the proposed strategy is an appropriate method for the implementation of relay selection and can achieve significant performance gains in terms of outage probability regardless of the symmetry or asymmetry of the channels. Compared with the AF scheme and the scheme using relay selection, the conventional JDF scheme and that using relay selection perform well at low signal-to-noise ratios (SNRs).

• Journal of the Korea Safety Management & Science
• /
• 제17권3호
• /
• pp.195-204
• /
• 2015

The live fire test has been playing a critical role in evaluating the goals-to-meet of the weapon systems which utilize the power of explosives. As such, the successful development of the test systems therein is quite important. The test systems development covers that of ranges and facilities including system-level key components such as mission control, instrumentation or observation, safety control, electric power, launch pad, and so on. In addition, proper operational guidelines are needed with well-trained test and operation personnel. The emerging weapon systems to be deployed in future battle field would thus have to be more precise and dynamic, smarter, thereby requiring more elaboration. Furthermore, the safety consideration is becoming more serious due to the ever-increasing power of explosives. In such a situation, development of live fire test systems seems to be challenging. The objective of the paper is on how to incorporate the safety and other requirements in the development. To achieve the goal, an architectural approach is adopted by utilizing both the system components relationship and safety requirement when advanced instrumentation technology needs to be developed and deteriorated components of the range are replaced. As an evaluation method, it is studied how the level of maturity of the test systems development can be assessed particularly with the safety requirement considered. Based on the concepts of both systems engineering and SoS (System-of-Systems) engineering process, an enhanced model for the system readiness level is proposed by incorporating safety. The maturity model proposed would be helpful in assessing the maturity of safety-critical systems development whereas the costing model would provide a guide on how the reasonable test resource allocation plan can be made, which is based on the live fire test scenario of future complex weapon systems such as SoS.

• Journal of the Korean earth science society
• /
• 제34권6호
• /
• pp.492-506
• /
• 2013

The historical accounts and materials about the eruption of Mt. Baekdusan as observed by the geological survey is now showing some signs of waking from a long slumber. As a response of the volcanic eruption of Mt. Baekdusan, water release may occur from the stored water in Lake Cheonjii caldera. The volcanic flood is crucial in that it has huge potential energy that can destruct all kinds of man-made structures and that its velocity can reach up to 100 km $hr^{-1}$ to cover hundreds of kilometers of downstream of Lake Cheonji. The ultimate goal of the study is to estimate the level of damage caused by the volcanic flood of Lake Cheon-Ji caldera. As a preliminary study a scenario-based numerical analysis is performed to build hydrographs as a function of time. The analysis is performed for each scenario (breach, magma uplift, combination of uplift and breach, formation of precipitation etc.) and the parameters to require a model structure is chosen on the basis of the historic records of other volcanos. This study only considers the amount of water at the rim site as a function of time for the estimation whereas the downstream routing process is not considered in this study.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• 제20권6호
• /
• pp.1171-1176
• /
• 2016

VANET are a special kind of MANET adapted to the communications between vehicles. In this work, we propose the models used for representing the communication among vehicles, vehicles mobility features, and VANET simulator using realistic vehicular mobility models. VANET requires that a traffic and network simulator should be used together to perform this test. But, simulator tool has been preferred over traffic simulation because it simple, easy and cheap. Goal of this paper is to create a simulation of Vehicular Ad-Hoc network for urban scenario which can be used for testing purposes. Such environment can be used while designing better MAC protocols in VANETs. We are evaluating the performance of two routing protocols namely AODV and DSDV. The comparison was based on the throughout, packet loss and end-to-end delay. We found that DSDV has less throughput performance and high routing overhead than AODV. On average end-to-end delay and packet loss, AODV performs better than DSDV.

• Journal of Internet Computing and Services
• /
• 제21권4호
• /
• pp.1-8
• /
• 2020

In order to reach Ultra-Reliable Low-Latency communication, one of 5G aims, Multi-access Edge Computing paradigm was born. The idea of this paradigm is to bring cloud computing technologies closer to the network edge. User services are hosted in multiple Edge Clouds, deployed at the edge of the network distributedly, to reduce the service latency. For mobile users, migrating their services to the most proper Edge Clouds for maintaining a Quality of Service is a non-convex problem. The service migration problem becomes more complex in high mobility scenarios. The goal of the study is to observe how user mobility affects the selection of Edge Cloud during a fixed mobility path. Mobility-Aware Service Migration (MASM) is proposed to optimize service migration based on two main parameters: routing cost and service migration cost, during a high mobility scenario. The performance of the proposed algorithm is compared with an existing greedy algorithm.