• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.79-85
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• 2017

It is critical that passengers should be given timely and correct escape or evacuation guidance from captain and crews when there are hazardous situations in a ship. Otherwise the consequences could be disastrous as "SEWOL Ferry" the South Korean passenger ship which sank in southern coastal area on 16th April 2014. Due to the captain's delayed evacuation decision and lack of sufficient number of crews to guide passengers' evacuation, the accident recorded many casualties, most of whom were high school students (302 passengers sank down with the ship while 172 rescued). Building a passenger ship with well-designed physical escape routes is one thing and guiding passengers to those escape routes in real disaster situation is another. Passengers get panic and move to a wrong direction, bottleneck makes situation worse, and even crews get panic also - passive static escape route signage and small number of trained crews might not be enough to take care of them. SESS (Smart Escape Support System) is being developed sponsored by South Korea Ministry of Ocean and Fisheries starting from 2016 with 4 years of roadmap. SESS comprises multiple active dynamic signage devices which communicate with real-time escape routing server software via LoRa (Long Range) proprietary wireless network.

• Journal of KIISE:Software and Applications
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• v.34 no.1
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• pp.79-94
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• 2007

In the ubiquitous computing age which uses a high quantity network, mobile devices such as wearable and hand-held ones with a small tamers and a wireless communication module will be widely used in near future. Thus, a lot of researches about an augmented game on mobile devices have been attempted recently. The existing augmented games used a traditional 'backpack' system and a pattern marker. The 'backpack' system is expensive, cumbersome and inconvenient to use, and because of the pattern marker, it is only possible to play the game in the previously installed palace. In this paper, we propose an augmented game called Flying Cake using a face region to create the virtual object(character) without the pattern marker, which manually indicates an overlapped location of the virtual object in the real world, on a small and mobile PDA instead of the cumbersome hardware. Flying Cake is an augmented shooting game. This game supplies us with two types: 1) a single player which attacks a virtual character on images captured by a camera in an outdoor physical area, 2) dual players which attack the virtual character on images which we received through a wireless LAN. We overlap the virtual character on the face region using a face detection technique, and users play Flying Cake though attacking the virtual character. Flying Cake supplies new pleasure to flayers with a new game paradigm through an interaction between the user in the physical world captured by the PDA camera and the virtual character in a virtual world using the face detection.

• Journal of KIISE:Computing Practices and Letters
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• v.11 no.5
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• pp.401-415
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• 2005

Owing to the improved wireless communication technologies, it is possible to provide streaming service of multimedia with PDAs and mobile phones in addition to desktop PCs. Since mobile client devices have low computing power and low network bandwidth due to wireless network, the transcoding technology to adapt media for mobile client devices considering their characteristics is necessary. Transcoding servers transcode the source media to the target media within corresponding grades and provide QoS in real-time. In particular, an effective load balancing policy for transcoding servers is inevitable to support QoS for large scale mobile users. In this paper, the resource weighted load distribution policy is proposed for a fair load balance and a more scalable performance in cluster-based transcoding servers. Our proposed policy is based on the resource weighted table and number of maximum supported users, which are pre-computed for each pre-defined grade. We implement the proposed policy on cluster-based transcoding servers and evaluate its fair load distribution and scalable performance with the number of transcoding servers.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.465-473
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• 2021

Since the past, ships have hoisted national flags as a means of indicating their nationality. Both domestically and internationally, laws and conventions related to the nationality and hoisting of the flag have been enacted because it is significant that the nationality of a ship is a matter of the jurisdiction of the ship. Nevertheless, there are differences in domestic and international regulations related to the hoisting of the flag of a ship, and if the flag is not hoisted irrespective of the intention, there may be a difference in interpretation as to whether or not the ship will be regarded unconditionally as a stateless ship. However, there is no disagreement locally or abroad about the necessity of indicating the nationality of ships. Therefore, I would like to propose a method to indicate and confirm the nationality of the ship by using wireless communication equipment with hoisting the flag as the only way to express its nationality, reflecting the situation of the era such as high-speed, larger and unmanned ship. Representatively, the method utilizes the automatic identification system(AIS), which is one of the equipment legally installed in the ship, and includes the ship's nationality in its information. If the nationality information is included in the AIS, nationality can be identified earlier and even from a distance, and there will not be instances of nationality not being identified because the flag is not hoisted or the flag is damaged. In addition, it is expected that the problem of nationality indication can be solved even when vessels are unmanned in future.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.4
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• pp.965-972
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• 2011

As an aged population has increased in Korea, the number of patients with chronic disease has soared up as well. The rapid increase of the chronic disease triggers a need of new paradigm of healthcare. In terms of data transmission of healthcare system, a use of data-transmission protocol based on bluetooth could be dismal in application of healthcare due to its postponement of connection. On the contrary, WPAN is evaluated to be proper to support the application of healthcare in restricted geographic areas. In addition, the bluetooth, a base of the current wireless network, doesn't support a special mechanism to cope up with emergent patients because of its delayed connection among devices. Against this backdrop, this study aims to design an integrated interface of multi bio-sensing and suggest a measuring and monitering system for the patients with chronic illnesses by using Zigbee of WPAN as a sufficient bandwidth is anticipated owing to frequent deliveries of complicated biological signals.

• Korean Journal of Remote Sensing
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• v.29 no.2
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• pp.253-261
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• 2013

Current surveying and spatial information technology incorporates information and communication technology and is user friendly. However, it is not convenient to use in the field because a connection to a computer, such as a laptop, tablet PC, or desktop PC, is needed to obtain the survey results and the coordinates of the surveyed points. To solve this problem, we developed an app that can display surveyed data on a map and the current survey results through a connection between a total station and smartphone using a Bluetooth wireless communication device. The app allows users to perform field work simultaneously with office work in the field, because it consists of Bluetooth, closed traverse survey, current status survey, and coordinate conversion modules. The proposed app should increase user convenience and the operational capability of the total station in the field.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.1
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• pp.19-27
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• 2007

Entering the 21st century, the demand on information service via mobile devices is skyrocketing along with the popularization of computers and mobile communication devices and the rapid development of wireless communication technology. In particular, as mobile device service such as LBS and Telematics becomes highlighted, the management of mobile devices is ever more drawing attention. However, since there is no fixed standard on geographical space data, many commercialized monitoring systems do not use common geographical space data but independent geographic information. Furthermore, as it is impossible to save location information of each mobile device by integrating such information after acquiring them, it is difficult to trace management. Therefore, in this paper, geographic data with DXF. DWG and SHP format, which are commonly used files, were created and visualized by GML format, OGC standard advice. And then, TMS(Trace Monitoring System of Mobile Device) that can trace and manage information after acquiring and saving space information that show the movement of users was implemented.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.11
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• pp.1135-1140
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• 2016

The main challenge in designing wearable WBANs is to guarantee the balance of QoS demands in the network with the low power constraints of limited battery powered nodes. Low power devices implanted in or attached to the body should be designed to meet minimum energy requirements due to their limited battery life and be small in size to be easily wearable. In this paper, we propose a method for optimizing channel allocation method that is compatible with the IEEE 802.15.6 standard, enables the maximum amount of power charge at idle, guarantees the QoS of a WBAN, and provides the reliable date transmission between nodes and hubs in the network. Our extensive simulations will show that the method we propose not only maximizes the QoS in packet transmission but also improves the level of energy efficiency.

• The Journal of Information Technology
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• v.5 no.1
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• pp.69-77
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• 2002

The Bluetooth is expected to be one of the most popular wireless telecommunication technology in the near future, and the protocol stack is essential to providing the various services with the Bluetooth-embedding systems or devices. The Bluetooth specification is an open, global specification defining the complete system, however, the protocol stack is usually implemented partly in hardware and partly as software running on its system, with different implementations partitioning the functionality between hardware and software in different ways. I investigate how to design and implement the Bluetooth protocol stack according to its specification. I focus on the HCI and the lower layer of the software protocol stack as a basic step for the development of our own protocol stack. As a result, paper provides how to partitioning the role of HCI layer, and how to implement the relationship between HCI packets, it's functionality and the flow control. Experiments show the discovering other Bluetooth devices and their connection. Furthermore experiments demonstrate the proper operation of data communication between the Bluetooth modules.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1B
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• pp.86-97
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• 2009

RTLS is a system for automatically locating and tracking people and objects. The TDOA-based RTLS determines the location of the tag by calculating the time differences of a signal received from the tag. In TDOA-based RTLS, time synchronization is essential to calculate the time difference between readers. This paper presents a precision time synchronization method for TDOA-based RTLS over IEEE 802.15.4. In order to achieve precision time synchronization in IEEE 802.15.4 radio, we analyzed the error factors of delay and jitter. We also deal with the implementation of hardware assisted time stamping and the Kalman filtering method to minimize the error factors. In addition, this paper described the experiments and performance evaluation of the proposed precision time synchronization method in IEEE 802.15.4 radio. The results show that the nodes in a network can maintain their clocks to within 10 nanoseconds offset from the reference clock.