• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.323-332
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• 2005

In this Paper, we design and implement an e-Learning system with dynamic learning contents Providing and re-time assignment system. The learner can select the dynamic learning contents Providing environments with test and Quiz Phase according to the learners' characters and interest to improve the learning effects. Also, we develop the real-time assignment system which is composed of multiple choice and essay test and can provide the interaction between teacher and learner immediately.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11A
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• pp.1035-1046
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• 2005

This paper analyzes the channel assignment techniques and their performance in the On Board Processing (OBP) satellite communication system. It suggests the new Continuous Rate Assignment (CRA) and Dynamic Rare Assignment (DRA) for improving the efficiency of channel assignment at the OBP switch. Mathematical analysis and simulation are given to evaluate the system performance. Aggregate real-time and non-real-time services are considered as different classes. Higher priority is given to voice and video real-time services to avoid delay variation. Onboard scheduler uses CRA and DRA ways to arrange the capacity allocation dynamically. An improved algorithm is given to make the channel more efficient by doing some evaluation of the switching matrix.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.5
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• pp.1249-1259
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• 1998

This paper proposes an efficient channel assignment method for real-time service in the IEEE 802.11 Wireless LAN system, and analyzes the supportability to real-time service and the channel utilzation of that through computer simulations. The improved MAC(Medium Access Control) protocol employing the proposed channel assignment method achieved good throughput over contention period as well as contention-free period by making real-time terminals transmit the information about their desiring value before starts of data transmissions. For performance evaluation of the proposed method, a simulation analyzing the variation of allocated bandwidths to terminals using real-time service and their buffer sizes wasexecuted. Real-time data traffics was modeled s 7-stae transition VBR sources, and asynchronous data traffics modeled as Poisson processes. In the simulation, the proposed method showed smaller variation of the bandwidth of each terminal and samller buffer size than the existing method, and also recorded good throughput over contention period.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.43-52
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• 2021

In weapon assignment studies to defend against threats such as ballistic missiles and long range artillery, threat assessment was partially lacking in analysis of various threat attributes, and considering the threat characteristics of warheads, which are difficult to judge in the early flight stages, it is very important to apply more reliable optimal solutions than approximate solution using LP model, Meta heuristics Genetic Algorithm, Tabu search and Particle swarm optimization etc. Our studies suggest Generic Rule based threat evaluation and weapon assignment algorithm in the basis of various attributes of threats. First job of studies analyzes information on Various attributes such as the type of target, Flight trajectory and flight time, range and intercept altitude of the intercept system, etc. Second job of studies propose Rule based threat evaluation and weapon assignment algorithm were applied to obtain a more reliable solution by reflection the importance of the interception system. It analyzes ballistic missiles and long-range artillery was assigned to multiple intercept system by real time threat assessment reflecting various threat information. The results of this study are provided reliable solution for Weapon Assignment problem as well as considered to be applicable to establishing a missile and long range artillery defense system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.211-220
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• 2017

The application of the theoretical model to real assembly lines has been one of the biggest challenges for researchers and industrial engineers. There should be some realistic approach to achieve the conflicting objectives on real systems. Therefore, in this paper, a model is developed to synchronize a real system (A discrete event simulation model) with a theoretical model (An optimization model). This synchronization will enable the realistic optimization of systems. A job assignment model of the assembly line is formulated for the evaluation of proposed realistic optimization to achieve multiple conflicting objectives. The objectives, fluctuation in cycle time, throughput, labor cost, energy cost, teamwork and deviation in the skill level of operators have been modeled mathematically. To solve the formulated mathematical model, a multi-objective simulation integrated hybrid genetic algorithm (MO-SHGA) is proposed. In MO-SHGA each individual in each population acts as an input scenario of simulation. Also, it is very difficult to assign weights to the objective function in the traditional multi-objective GA because of pareto fronts. Therefore, we have proposed a probabilistic based linearization and multi-objective to single objective conversion method at population evolution phase. The performance of MO-SHGA is evaluated with the standard multi-objective genetic algorithm (MO-GA) with both deterministic and stochastic data settings. A case study of the goalkeeping gloves assembly line is also presented as a numerical example which is solved using MO-SHGA and MO-GA. The proposed research is useful for the development of synchronized human based assembly lines for real time monitoring, optimization, and control.

• Journal of the Korean Society for Railway
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• v.11 no.4
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• pp.364-370
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• 2008

In this paper, we proposed new sensor network architecture with autonomous robots based on beacon mode and implemented real time monitoring system in real test-bed environment. The proposed scheme offers beacon based real-time scheduling for reliable association process with parent nodes and dynamically assigns network address by using NAA (Next Address Assignment) mechanism. For the large scale multi-sensor processing, our real-time monitoring system accomplished the intelligent database processing, which can generate not only the alert messages to the civilians but also process various sensing data such as fire, air, temperature and etc. Moreover, we also developed mobile robot which can support network mobility. Though the performance evaluation by using real test-bed system, we illustrate that our proposed system demonstrates promising performance for emergence monitoring systems.

• The Journal of the Korea Contents Association
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• v.18 no.8
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• pp.118-126
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• 2018

In order to dominate the multiple-targets of high threat in the initial stage of combat, it is necessary to maximize the combat effect by rapidly firing as many weapons as possible within a short time. Therefore, it is mandatory to establish the effective weapon allocation and utilize them for the combat. In this paper, we propose a weapon assignment algorithm for rapid reaction in multi-target and multi-weapon environments. The proposed algorithm maximizes the combat effect by establishing the fire plan that enables the rapid action with the operation of low complexity. To show the superiority of our algorithm, we implement the evaluation and verification of performances through the simulation and visualization of our algorithm. Our experimental results show that the proposed algorithm perform the effective weapon assignment, which shows the high target assignment rate within the fast hour even under the large-scale battle environments. Therefore, our proposed scheme are expected to be highly useful when it is applied to real weapon systems.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.5
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• pp.462-469
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• 2023

In this study, we propose a method for evaluating the risk of collision between ships to support determination on the risk of collision in a situation in which ships encounter each other and to prevent collision accidents. Because several uncertainties are involved in the navigation of a ship, must be considered when evaluating the risk of collision. We apply the Dempster-Shafer theory to manage this uncertainty and evaluate the collision risk of each target vessel in real time. The distance at the closest point approach (DCPA), time to the closest point approach (TCPA), distance from another vessel, relative bearing, and velocity ratio are used as evaluation factors for ship collision risk. The basic probability assignments (BPAs) calculated by membership functions for each evaluation factor are fused through the combination rule of the Dempster-Shafer theory. As a result of the experiment using automatic identification system (AIS) data collected in situations where ships actually encounter each other, the suitability of evaluation was verified. By evaluating the risk of collision in real time in encounter situations between ships, collision accidents caused by human errora can be prevented. This is expected to be used for vessel traffic service systems and collision avoidance systems for autonomous ships.

• The KIPS Transactions:PartD
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• v.8D no.5
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• pp.533-542
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• 2001

In this paper, we present a scheduling method for real-time mobile transaction manager in mobile computing environment. The proposed method checks whether a transaction is executable or not. It is able to by considering not only the deadline of real-time data in mobile hosts. And then, it schedules the real-time mobile transactions by making optimal execution window based on the priority queue, while considering transaction value and deadline. Disconnection with mobile hosts is monitored in selecting the transaction for execution. Using the proposed method reduces the number of restarting times after transaction aborts which is caused by the violation of the validity constraints of real-time data. And in has merits of maximizing the sum of values of real-time mobile transactions which meet the deadline. The performance evaluation demonstrates that the number of committed real-time transactions within the deadline is improved by 20%. This method can be used in real-time mobile transaction manager is such environments as cellular communications, emergency medicine information system and so on.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.281-286
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• 2004

It's important to operate the yard for improving to the productivity in container terminal effectively. Because the automated container terminal(ACT) has storage yard of automation and horizon, it's character is different from conventional terminal. As the automation yard in ACT is operated by the automated equipments, it needs to an efficient storage plan which is connected the automated equipment, the external truck, the shipment etc.. Hut the traditional method of storage plan is the space assignment problem. The efficiency of yard decreases and it is brought about increase of shipment time, because real-time automated equipments and present yard status is not reflected in. In order to solve this problems, we propose the algorithm for real-time storage location of container considering shipment plan, yard status and the state of ATC.