• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.10
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• pp.1941-1948
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• 2016

The incident during commuting to school happened frequently in these days, such that the government announced the student commuting safety policy for addressing to implement the safety management system of the unsafer school commuting zone. In this paper, a commuting tracking system is proposed that notifies the location of vehicles and the boarding status of student using BLE beacon and smart phone GPS function. The commuting tracking system that gets the data from the system server of driver's smart phone GPS location and UUID of the beacon which had provided students has configured to provide notifications to parents and related administrators. It provides real-time information about whether a student boarding, boarding times and bus locations for parents and administrators. It verifies the disembarking time for each student and also provides to driver to secure if any student tries to board the wrong school bus and if any students is left behind in the bus.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.1-7
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• 2010

In this paper, a high-performance fault-tolerant switching network using a deflection self-routing was proposed. From an abstract algebraic analysis of the topological properties of the Delta network, which is a baseline switching network, we derive the Multidimensional Ring-Delta network: a multipath switching network using a deflection self-routing algorithm. All of the links including already existing links of the Delta network are used to provide the alternate paths detouring faulty/congested links. We ran a simulation analysis under the traffic loads having the non-uniform address distributions that are usual in Internet. The throughput of $1024\;{\times}\;1024$ switching network proposed is better than that of the 2D ring-Banyan network by 13.3 %, when the input traffic load is 1.0 and the hot ratio is 0.9. The reliability of $64\;{\times}\;64$ switching network proposed is better than that of the 2D ring-Banyan network by 46.6%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8B
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• pp.751-759
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• 2009

Due to the advance of WLAN technology, the use of the multimedia service such as the video streaming service has been increased in the home network. However, we need to study the method which decreases the transmission delay and the frame loss rate to provide QoS of the video streaming service. Therefore, this paper proposes an active buffer management mechanism to guarantee QoS of the streaming service in IEEE 802.11e EDCA. The proposed protocol discards the frame in the HoL of the buffer based on the importance of each frame and the virtual transmission delay of frame newly arriving at the buffer. In the simulation results, the proposed algorithm not only decreases the frame loss probability of important I and P frames but also stabilizes the transmission delay. It may increase the QoS of video streaming services.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.9
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• pp.369-374
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• 2014

Path generation methods are required for safe and efficient driving in unmanned autonomous vehicles. There are two kinds of paths: global and local. A global path consists of all the way points including the source and the destination. A local path is the trajectory that a vehicle needs to follow from a way point to the next in the global path. In this paper, we propose a novel method for local path generation through machine learning, with an effective curve function used for initializing the trajectory. First, reinforcement learning is applied to a set of candidate paths to produce the best trajectory with maximal reward. Then the optimal steering angle with respect to the trajectory is determined by training an artificial neural network. Our method outperformed existing approaches and successfully found quality paths in various experimental settings, including the cases with obstacles.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.3
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• pp.63-72
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• 2014

The exchangeable battery electric bus is an eco-friendly public transportation vehicle. Due to the technological limitation, however, it should repeatedly change batteries with charged ones. The unmanned battery exchangeable electric bus being studied in Korea can exchange batteries automatically by using a battery swapping system. In this paper, we propose an unmanned battery exchangeable electric bus management system. The proposed system provides two services: the bus information service and the battery change scheduling service. The bus information service is the existing traditional metropolitan area bus information systems, which inform bus passengers how long they should wait for the buses. Our second service assigns a low-battery bus, which needs to change the batteries, to the battery swapping system, which stores fully-charged batteries. To validate the proposed system, we model the system by using the DEVS formalism. The simulation result shows that the proposed system provides the services properly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1A
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• pp.91-103
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• 2005

In designing a video-on-demand (VoD) system, the major challenge may be how to reduce the channels concurrently used maintaining the client's waiting time. For this reason, the various architectures which integrate the multicast streams with the unicast streams were suggested in order to improve channel efficiency in recent years. In combining multicast with unicast, the ways to group the unicast channels together are important so that clients can share the multicast transmission channels. This paper proposes a hybrid video-on-demand system which gathers the unicast channels in new ways and shares multicast transmission channels efficiently by using dynamic channel allocation architecture. The numerical results demonstrate that the proposed architecture in some case achieves performance gain of $551{\%}$ compared to existing architecture. This paper presents procedure of channel release and reuse, performance analysis, and simulation results of the dynamic channel allocation architecture.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.3
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• pp.300-309
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• 2003

The Japanese developed the first Car navigation system in 1981 with the advent of Honda, which was known as the car inertial navigation system. Now days, It is possible to search the shortest route to and from places and arrival time using the internet via cell phone to the driver based on GIS and GPS. However, even with a good navigation system, it losses the shortest route when there is an average speed of the vehicle being between S-15 kilometers. Therefore, in order to improve the vehicle waiting time and average vehicle speed, we are suggesting an optimal green time algorithm using fuzzy adaptive control, where there are different traffic intersection lengths, and lanes. In this paper, to be able to assist the driver and forecast the optimal traffic information with regards to the road conditions; dangerous roads, construction work and estimation of arrival time at their destination using internet.

• Management & Information Systems Review
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• v.35 no.2
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• pp.1-12
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• 2016

In this study, price discovery between the KOSPI200 spot, and leveraged ETFs(Leveraged KODEX, Leveraged TIGER, Leveraged KStar) is investigated using the vector error correction model(VECM). The main findings are as follows. Leveraged KODEX(Leveraged TIGER, Leveraged KStar) and KOSPI200 spot are cointegrated in most cases. There is no interrelations between the movement of Leveraged KODEX(Leveraged TIGER, Leveraged KStar) and KOSPI200 spot markets in case of daily data. Namely, in daily data, Leveraged KODEX(Leveraged TIGER, Leveraged KStar) doesn't plays more dominant role in price discovery than the KOSPI200 spot.

• Journal of the Korea Society for Simulation
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• v.22 no.1
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• pp.63-75
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• 2013

The School Bus Routing Problem(SBRP) seeks to plan an efficient schedule of a fleet of school buses that must pick up student from various bus stops and deliver them by satisfying various constraints; maximum capacity of the bus, maximum riding time of students, arrival time between a school's time window. By extending the existing SBRP, we consider a case study of SBRP with allowance of mixed-loading and dynamic arrivals reflecting the school bus operation of university in Korea. Our solution procedure is based on constructing the initial solution using sweep algorithm and then improving solution within the framework of the evolutionary approach known as efficient meta-heuristics. By comparing the various scenarios through the constraints relaxation for reflecting the real operational strategies, we assess the merit of our proposed procedure.

• Journal of the Korea Society of Computer and Information
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• v.18 no.10
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• pp.47-54
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• 2013

In this paper, the structural design of optical Internet is analyzed and by using UNI (User Network Interface) signaling protocol an optical transmission experiment was performed. The hierarchical structure of the basic optical Internet consists of the backbone network, the service network and the access network. The necessary functions for each layer were described as follows: Control structure of the optical transport layer, network operation and management structure, internetworking technology of sub networks, routing and signaling technology. By using UNI signaling protocol from OIF (Optical Internetworking Forum), the optical transmission in the proposed structure of the optical Internet network was experimented. By the traffic generation of LSP (Label Switched Path) data packets along the route-configuration was delivered to UNI. Finally, by showing the value of TCP (Transmission Control Protocol) packets the optical transmission was completely and successfully demonstrated.