• Journal of KIISE:Information Networking
• /
• v.31 no.3
• /
• pp.289-297
• /
• 2004

State-of-the-art wireless communication networks allow dynamic relocation of mobile terminals. A location management mechanism is required to keep track of a mobile terminal for delivering incoming calls. In this paper, we propose a fuzzy logic-based selective paging method to reduce paging cost. In the proposed fuzzy logic-based location management method, the location update uses the area-based method that uses direction-based together with movement-based methods, and the location search uses the fuzzy logic-based selective paging method based on the mobility information of mobile terminals. A partial candidate paging area is selected by fuzzy control rules, then the fuzzy logic-based selective paging method pages only the cells within the partial candidate paging area. The performance of proposed fuzzy logic-based location management method is to be evaluated by both an analytical model and a simulation, and is compared with those of LA and BVP methods. From these evaluation results, we know that the proposed fuzzy logic-based location management method provide better performance than other location management methods.

• KIPS Transactions on Computer and Communication Systems
• /
• v.2 no.7
• /
• pp.293-302
• /
• 2013

Home network providers have many worries about providing home network services with an expandable, reliable, flexible and low-cost structure according to the expanding market environment. The existing client-server system has various problems such as complexity and high costs in providing home network services. In this paper we propose the P2P-SIP structure. P2P communication terminal supporting access of distributed resources provides functions which the existing SIP-based network devices have. Because diverse terminals in a home network access through networks, also, partitioning network domains with home gateways to manage, and applying the network-based PMIPv6(Proxy Mobile IPv6) technology considering mobility of terminals would help to have a more efficient home network structure. Especially, the proposed P2P-SIP structure proves itself as a very efficient structure to have an outstanding expandability among different home networks in a region, and to reduce maintenance costs.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37B no.12
• /
• pp.1148-1159
• /
• 2012

It is of great significance in the NGN - which supports a ubiquitous network environment in which users can use multiple devices and all the devices are connected to networks - to support the terminal mobility as well as service continuity. The IMS architecture, which is considered as session control layer in the NGN, exists to support a wide range of advanced new services in addition to the traditional voice and data connectivity offerings of "old" telecommunications. The recent IMS specification also defines IUT (Inter UE Session Transfer) functionality in order to support service continuity in the NGN. However, service continuity in IMS has a limitation that two terminals involved in session transfer should belong to the same user. In this paper, we proposed a new device discovery mechanism for IMS and extended UEs with a few capabilities to overcome some of IMS's limitations. We also analysed how much overhead of the proposed method in terms of signaling cost will be.

• Journal of Sensor Science and Technology
• /
• v.15 no.1
• /
• pp.58-64
• /
• 2006

In this study, we describe a low-temperature wafer-level thermocompression bonding using electroplated gold seal line and bonding pads by electroplating method for RF-MEMS devices. Silicon wafers, electroplated with gold (Au), were completely bonded at $320^{\circ}C$ for 30 min at a pressure of 2.5 MPa. The through-hole interconnection between the packaged devices and external terminal did not need metal filling process and was made by gold films deposited on the sidewall of the throughhole. This process was low-cost and short in duration. Helium leak rate, which is measured to evaluate the reliability of bonded wafers, was $2.7{\pm}0.614{\times}10^{-10}Pam^{3}/s$. The insertion loss of the CPW packaged was $-0.069{\sim}-0.085\;dB$. The difference of the insertion loss between the unpackaged and packaged CPW was less than -0.03. These values show very good RF characteristics of the packaging. Therefore, gold thermocompression bonding can be applied to high quality hermetic wafer level packaging of RF-MEMS devices.

• Smart Structures and Systems
• /
• v.6 no.8
• /
• pp.939-951
• /
• 2010

A low-cost wireless sensor network (WSN) solution with highly expandable super and simple nodes was developed. The super node was designed as a sensing unit as well as a receiving terminal with low energy consumption. The simple node was designed to serve as a cheaper alternative for large-scale deployment. A 12-bit ADC inputs and DAC outputs were reserved for sensor boards to ease the sensing integration. Vibration and thermal field tests of the Chi-Lu Bridge were conducted to evaluate the WSN's performance. Integral acceleration, temperature and tilt sensing modules were constructed to simplify the task of long-term environmental monitoring on this bridge, while a star topology was used to avoid collisions and reduce power consumption. We showed that, given sufficient power and additional power amplifier, the WSN can successfully be active for more than 7 days and satisfy the half bridge 120-meter transmission requirement. The time and frequency responses of cables shocked by external force and temperature variations around cables in one day were recorded and analyzed. Finally, guidelines on power characterization of the WSN platform and selection of acceleration sensors for structural health monitoring applications were given.

• The KIPS Transactions:PartD
• /
• v.8D no.3
• /
• pp.265-272
• /
• 2001

In case of implementing a complicated application like WAP (Wireless Application Protocol) in a mobile terminal with the characteristics of bare machine and versatile kernel aspects of which are control, interrupt and IPC(Inter Process Communication), a special methodology should be needed. If not, it will cause more cost and human resources, even delayed product into launching for the time-to-market. This paper suggests AKL, (Abstract Kernel Layer) for the design and implementation of WAP on basis of multi-platform. AKL is running on the various kernel including REX, MS-DOS, MS-Window, UNIX and LINUX. For the purpose of it, AKL makes machine-dependant features be minimized and supports a consistent interface on API (Application Program Interface) point of view. Therefore, it makes poring times of a device be shorten and makes easy of maintenance. We validated our suggestion as a consequent of porting WAP into PlamV PDA and mobile phone with AKL.

• KIPS Transactions on Computer and Communication Systems
• /
• v.3 no.3
• /
• pp.81-86
• /
• 2014

According to the development of streaming services with P2P and mobile network technologies, researches to enhance the service quality in mobile environment have been proposed. However, streaming services considering high-speed mobile environment and characteristics of heterogenous terminals have been hindered from being provided with the required quality from user because of bandwidth congestion between selfish peers of existing P2P system. It is also prone to long delay and loss in accordance with the repeated traffic amounts because there are no optimized solution for traffic localization. The structure to enhance peer contribution for service differentiation and peer selection with clustering scheme with location information of terminal can satisfy both users and service providers with service quality and efficiency. In this paper, we propose an incentive mechanism and resource distribution scheme with user contribution and traffic cost information based on user location, which make mobile users increase the satisfaction of service quality in LTE environments.

• Journal of Digital Contents Society
• /
• v.19 no.1
• /
• pp.181-191
• /
• 2018

With the development of IT, hacking crimes are becoming intelligent and refined. In Emergency response, Big data analysis in information security is to derive problems such as abnormal behavior through collecting, storing, analyzing and visualizing whole log including normal log generated from various information protection system. By using the full log data, including data we have been overlooked, we seek to detect and respond to the abnormal signs of the cyber attack from the early stage of the cyber attack. We used open-source ELK Stack technology to analyze big data like unstructured data that occur in information protection system, terminal and server. By using this technology, we can make it possible to build an information security control system that is optimized for the business environment with its own staff and technology. It is not necessary to rely on high-cost data analysis solution, and it is possible to accumulate technologies to defend from cyber attacks by implementing protection control system directly with its own manpower.

• Journal of Korea Port Economic Association
• /
• v.19 no.2
• /
• pp.1-32
• /
• 2003

The purpose of this study is to identify and evaluate the competitiveness of ports in ASEAN(Association of Southeast Asian Nations), which plays a leading role in basing the hub of global logistics strategies as a countermeasure in changes of logistics environments. This region represents most severe competition among Mega Hub ports in the world in terms of container cargo throughput at the onset of the 21st century. The research method in this study accounted for overlapping between attributes, and introduced the HFP method that can perform mathematical operations. The scope of this study was strictly confined to the ports of ASEAN, which cover the top 100 of 350 container ports that were presented in Containerization International Yearbook 2002 with reference to container throughput. The results of this study show Singapore in the number one position. Even when we compare with major ports in Korea (after getting comparative ratings and applying the same data and evaluation structure), the number one position still goes to Singapore and then Busan(2) and Manila(2), followed by Port Klang(4), Tanjung Priok(5), Tanjung Perak(6), Bangkok(7), Inchon(8), Laem Chabang(9) and Penang(9). In terms of the main contributions of this study, it is the first empirical study to apply the combined attributes of detailed and representative attributes into the advanced HFP model which was enhanced by the KJ method to evaluate the port competitiveness in ASEAN. Up-to-now, none has comprehensively conducted researches with sophisticated port methodology that has discussed a variety of changes in port development and terminal transfers of major shipping lines in the region. Moreover, through the comparative evaluation among major ports in Korea and ASEAN, the presentation of comparative competitiveness for Korean ports is a great achievement in this study. In order to reinforce this study, it needs further compensative research, including cost factors which could not be applied to modeling the subject ports by lack of consistently quantified data in ASEAN.

• Journal of the Korean Society for Railway
• /
• v.20 no.5
• /
• pp.612-624
• /
• 2017

As the existing metropolitan area metropolitan railway operates on a one-to-one basis, which leads to long travel times, its competitiveness with other means of transportation is deteriorating. Since there is a limit to attracting road traffic by rail, there is a continuing societal demand to expand express train service. Especially in the northern and the southwestern parts of the metropolitan area, a public transportation network system with express function, connecting to the city center of Seoul, is needed because of the social cost of the increase of traffic congestion and the increase of the travel time. The most efficient express service in Korea is Seoul Subway Line 9, which runs in 27 minutes from Gimpo Airport to the high speed terminal; this is a 40% shorter time compared to 44 minutes by car; the congestion in this area is up to 240%, so the preference for this train is quite high. The technical results of this study are expected to contribute to the implementation of an express service metropolitan railway.