• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.132-133
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• 2023

The safe evacuation of people during disasters is of utmost importance. Various life safety evacuation simulation tools have been developed and implemented, with most relying on algorithms that analyze maps to extract the shortest path and guide agents along predetermined routes. While effective in predicting evacuation routes in stable disaster conditions and short timeframes, this approach falls short in dynamic situations where disaster scenarios constantly change. Existing algorithms struggle to respond to such scenarios, prompting the need for a more adaptive evacuation route algorithm that can respond to changing disasters. Artificial intelligence technology based on reinforcement learning holds the potential to develop such an algorithm. As a fundamental step in algorithm development, this study aims to evaluate whether an evacuation algorithm developed by reinforcement learning satisfies the performance conditions of the evacuation simulation tool required by IMO MSC.1/Circ1533.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.99-107
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• 2024

This paper introduces an emergency response system in urban air mobility scenarios. A biometric responsive smartwatch was designed to monitor passengers' real-time heart rates. When an anomaly was detected, the system would send an alert via Morse code vibration and voice notification. It was integrated with the assumed control system of the ROS environment and communicates to implement a system for generating the shortest path for emergency landing to a nearby vertical port during urban air mobility operations. System stability was verified through high-fidelity simulation environments and testing based on actual geographic locations. Our technology improved the reliability and convenience of urban air mobility, demonstrating its effectiveness through simulations and tests in real-world scenarios.

• Journal of Korean Society of Transportation
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• v.28 no.2
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• pp.7-19
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• 2010

Users of metropolitan railroad is increased continuously because of its various advantage such as comfortableness, convenience and punctuality. Thus, several local government including Seoul considered new installation or extension of railroads and four railroad operators maintain seventeen lines at present. After public transportation reforms in 2004 and integrated discount fare system in 2007, public transportation become more convenient in many aspects. However, these trials gives much more complex allocating problems of revenues among public transportation operators. In this paper, we deal with revenue allocating problems among public transportation operators after integrated discount fare system in 2007. Specifically, this study focuses on allocating revenues to metropolitan railroad operators by using RF card data. This research roughly proposes the methodology of O/D extraction from RF card data, generalized cost estimation and allocating revenue algorithm. We use RF card data in order to draw out exact individual O/D data and try to compare our results with those of Korea Smart Card Company. In generalized cost estimation, survey study about transfer factors is conducted for accurate estimation of generalized cost function. Lastly, new allocating revenue algorithm using k-path and non-dominated path concept is suggested. It is expected that case study is also performed with real revenues and O/D data in order to check up the application. Preposed methodology in this research can contribute to solve present and future revenue allocating issues according to the introduction of LRT and private railroad.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1338-1341
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• 2004

In this paper, we have proposed a new approach of routing and wavelength assignment algorithms, called Possible Available Wavelength (PAW) algorithm. The weight of a link is used as the main factor for routing decision in PAW algorithm. The weight of a link is defined as a function of hop count and available wavelengths. This function includes a determination factor of the number of wavelengths that are being used currently and are supposed to be available after a certain time. The session requests from users will be routed on the links that has the greatest number of link weight by using Dijkstra's shortest path algorithm. This means that the selected lightpath will has the least hop count and the greatest number of possible available wavelengths. The impact of proposed link weight computing function on the blocking probability and link utilization is investigated by means of computer simulation and comparing with the traditional mechanism. The results show that the proposed PAW algorithm can achieve the better performance in terms of the blocking probability and link utilization.

• Journal of Digital Contents Society
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• v.18 no.6
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• pp.1119-1125
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• 2017

Genres and actions of stories can be used to classify stories, and used effectively as well for visualizing story properties. This paper proposes a Genre-Action coordinate system for visualizing story property data in 2-dimension that has similarities between the genre and action items along the axes, i.e. a property of spatial continuum. With the proposed Genre-Action coordinate system we found that the genre and action items in the axes are arranged according to their similarities and we were able to achieve a spatially meaningful visualization of story properties where the related data form clusters.

• Journal of KIISE:Software and Applications
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• v.36 no.6
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• pp.462-470
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• 2009

We propose a wearable system to help the visually impaired persons for walking safely to destination. If a user selects a destination, the system guides the user to destination with position data from GPS receiver and shortest path algorithm. At the same time, after acquiring complex spatial structures in front of the user with ultrasonic sensors, we categorize them into several predefined patterns, and determine an avoidance direction by estimating the patterns. As a result, visually impaired persons can arrive at destination safely and correctly without others help.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.7
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• pp.1252-1273
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• 2011

In Web Service Composition (WSC) area, services selection aims at selecting an appropriate candidate from a set of functionally-equivalent services to execute the function of each task in an abstract WSC according to their different QoS values. In despite of many related works, few of previous studies consider transactional constraints in QoS-aware WSC, which guarantee reliable execution of Composite Web Service (CWS) that is composed by a number of unpredictable web services. In this paper, we propose a novel global selection-optimal approach in WSC by considering both transactional constraints and end-to-end QoS constraints. With this approach, we firstly identify building rules and the reduction method to build layer-based Directed Acyclic Graph (DAG) model which can model transactional relationships among candidate services. As such, the problem of solving global optimal QoS utility with transactional constraints in WSC can be regarded as a problem of solving single-source shortest path in DAG. After that, we present Graph-building algorithms and an optimal selection algorithm to explain the specific execution procedures. Finally, comprehensive experiments are conducted based on a real-world web service QoS dataset. The experimental results show that our approach has better performance over other competing selection approaches on success ratio and efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.5
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• pp.1222-1228
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• 1998

Most of researchers have tried to find heuristic methods for near-optimal solutions of establishing light paths with minimum number of wavelengths in wavelengh-routed optical networks. In order to provide a performance measure for heuristic approaches, we propose a practical approach for a lower bound of the number of wavelengths which is required to provide full connections in WDM-based optical transport networks. This method is based on a path-flow formulation using K-shortest paths for each connection. Compared with a general link-flow formulation, the proposed method has much lower complexity and so needs much less calcuation tiem while it gives the same results as a general link-flow formulation in some sample networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1048-1058
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• 1999

This paper compares some architectures to achieve the optimized WDM architecture for all optical transport network, the comparison is presented in terms of the number of required wavelength and LT. These architecture types are PPWDM, SHWDM, DHWDM and fully optical WDM. Topology is a static ring network where the routing pattern is fixed and traffic pattern has uniform demand. This paper also proposes an algorithm for the wavelength assignment for a folly optical WDM ring network which has full mesh traffic pattern. The algorithm is based on heuristic algorithm which assigns traffic connections according to their respective shortest path. Traffic described here that is to be passed through can be routed directly within the optical layer instead of having the higher layer to handle it.

• Journal of Korean Institute of Industrial Engineers
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• v.37 no.2
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• pp.132-143
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• 2011

This paper deals with a coal supply planning problem for power plants. We propose a mathematical optimization model to make decisions for coal pile sections, movement of reclaimers, and operation time of conveyor belts. The objective of the proposed model is to minimize the total operation time of conveyor belts and total movement time of reclaimers. The algorithm firstly selects a pile section by considering both the location of reclaimers and the stock amount on that pile section. And then the shortest path from the selected pile section has to be put into the operation schedule and check whether the total operation time is satisfied. Then finally the new schedule is updated. To this end, we have tested the proposed algorithm comparing with the general standard optimization package for the simplified problem SCSPP. From the numerous test runs for comparing with the existing coal supply scheduling methods, We see that the proposed model may improve the coal supply operation by reducing significant coal supply costs.