• Journal of Mechanical Science and Technology
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• v.19 no.3
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• pp.756-767
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• 2005

This paper presents a decentralized motion control method of welding mobile manipulators which use for welding in many industrial fields. Major requirements of welding robots are accuracy, robust, and reliability so that they can substitute for the welders in hazardous and worse environment. To do this, the manipulator has to take the torch tracking along a welding trajectory with a constant velocity and a constant heading angle, and the mobile-platform has to move to avoid the singularities of the manipulator. In this paper, we develop a kinematic model of the mobile-platform and the manipulator as two separate subsystems. With the idea that the manipulator can avoid the singularities by keeping its initial configuration in the welding process, the redundancy problem of system is solved by introducing the platform mobility to realize this idea. Two controllers for the mobile-platform and the manipulator were designed, respectively, and the relationships between two controllers are the velocities of two subsystems. Control laws are obtained based on the Lyapunov function to ensure the asymptotical stability of the system. The simulation and experimental results show the effectiveness of the proposed controllers.

• ETRI Journal
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• v.19 no.3
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• pp.186-201
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• 1997

In this paper, a home location register (HLR) for CDMA mobile communication system (CMS) is introduced. It stores the mobile station (MS) subscribers locations and supplementary service information. Call processing procedures for HLR are developed to receive and store subscriber's location coming from mobile exchange (MX) during the location registration, and to transfer subscriber's location and supplementary service information to the MX during the mobile-terminated call setup. For fast call processing by increasing database access speed, a memory-resident database management system is devised. For Easy and secure HLR operation, administration and maintenance functions and overload control mechanisms are implemented. Designed HLR hardware platform is expandable and flexible enough to reallocated software blocks to any subsystems within the platform. It is configurable according to the size of subscribers. An authentication center (AC) is developed on the same platform. It screens the qualified MS from the unqualified. The calls to and from the unqualified MS are rejected in CMS. To authenticate the MS, the AC generates a new authentication parameter called "AUTHR" using shared secret data (SSD) and compared it with the other AUTHR received from the MS. The MC also generates and stores seed keys called "A-keys" which are used to generate SSDs. The HLR requirements, the AC requirements, software architecture, hardware platform, and test results are discussed.

• Informatization Policy
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• v.26 no.2
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• pp.3-23
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• 2019

This review article summarizes the trends and issues around the mobility business and government regulations in Korea. Key issues identified involve unclear government regulations, conflict management between key stakeholders, platform labor, and regional conflicts. The study then offers an overview of the current government regulations on the mobility business and conflict management, along with some policy recommendations in the areas of linking conflict resolution efforts with the welfare safety net, and corporates' social responsibility for the sustainable ecosystem. Ultimately, an ecosystem is required for multiple ministries and stakeholders to participate in the process of improving the regulations, as well as a control tower (government agency) who plays the pivotal role as a coordinator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.9
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• pp.806-813
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• 2012

In a cloud computing environment, various solutions were introduced to provide the service to users such as Infrastructure as a Service (IaaS), Platform as a Service (PaaS), Software as a Service (SaaS) and Desktop as a Service (DaaS). Nowadays, Mobile as a Service (MaaS) to provide the mobility in a cloud environment. In other words, users must have access to data and applications even when they are moving. Thus, to support the mobility to a mobile Thin-Client is the key factor. Related works to support the mobility for mobile devices were Mobile IPv6 and Proxy Mobile IPv6 which showed performance drawbacks such as packet loss during hand-over which could be very critical when collaborating with cloud computing environment. The proposed model in this paper deploys middleware and replica servers to support the data transmission among cloud and PMIPv6 domain. It supports efficient mobility during high-speed movement as well as high-density of mobile nodes in local mobility anchor. In this paper, through performance evaluation, the proposed scheme shows the cost comparison between previous PMIPv6 and verifies its significant efficiency.

• Journal of Communications and Networks
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• v.6 no.4
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• pp.295-306
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• 2004

In this paper, a novel air-interface is presented for Fleet-Net1, a self-organizing network for inter-vehicle and vehicle-toroadsidecommunication. The air-interface is based upon the lowchip-rate version of UMTS/TDD. To adapt the cellular UMTS standard to an air-interface for ad hoc networks, changes of the physical layer, medium access control sub-layer and radio resource management are required. An overview of the required modifications is given here. Particularly, a decentralized synchronization mechanism is presented and analyzed by means of simulations. Furthermore, changes for the medium access control are explained in detail, which allow for an efficient operation in partly meshed networks and prioritization. Performance results of the overall system considering throughput and delay are derived by means of analytical evaluations and event-driven simulations. Based on realistic mobility models, it is shown that the presented solution provides a robust communication platform even in vehicular environments. The proposed air-interface is a cost-effective solution not only for inter-vehicle communication, but also for ad hoc networking in general, benefiting from the mass-market of UMTS.

• Acta Via Serica
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• v.5 no.2
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• pp.51-90
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• 2020

The city of Sumqayit in Azerbaijan was famous in the USSR for its chemical plants, which supplied the whole country with plastics, detergents, and fertilizers. While production increased in the post-WWII period, young people from remote Caucasian villages were attracted as workers to the industrial settlement on the shore of the Caspian Sea and worked together with specialists from all over the USSR. Migration did not stop when the USSR collapsed. To the contrary, mobility increased as Azerbaijani refugees from Armenia and IDPs from Karabakh fled to Sumqayit, which grew to become the second-largest city of Azerbaijan. Although a generation has passed since the ceasefire, IDPs still are separately administered. In the last 20 years, more and more internal migrants have chosen the Greater Baku Region as their destination, mostly finding jobs in the informal labor market. In the post-independence transformative period, informal housing has offered migrants a place to stay in the city. Sumqayit can be regarded as an arrival city, an established urban platform for migrants who prefer internal over transnational migration.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.361-362
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• 2022

As the importance of maritime communication in a cross-cultural onboard working environment grows, the importance of developing systematic supporting aids both for learning and teaching maritime English has been emphasized. Given that English communication proficiency is one of the most critical factors in determining a seafarer's competency, a systemic supporting system for enhancing maritime English communication capabilities is essential not only for them to professionally carry out and conduct assigned duties onboard, but also for them to navigate success in their lives through increased labour mobility both at sea and onshore. The APEC Seafarers Excellence Network initiates the production of Maritime English Communication Packages for seafarers in APEC regions, under the leadership of the Republic of Korea. This paper introduces the design of APEC SEN Maritime English Communication Packages, which include textbooks, audio-lingual materials, online/mobile life-long learning platform and testing aids, ultimately for upand re-skilling of seafarers to increase their employability, mobility and preparedness for the future shipping industry where globalisation is expected to further accelerate.

• The Transactions of the Korea Information Processing Society
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• v.7 no.4
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• pp.1217-1226
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• 2000

Traditionally, Mobile Teletraffic model consists of two sub-models, i.e. the network traffic model and the traffic source model. In this paper, we present the traffic source model by developing MobCall (Mobile Call Simulator) which analyses various mobile wireless environments based on regional characteristics that the base stations are located. User mobility is presented by regional average vehicle speeds and the transportation share rate. Moreover, the user mobility on subway, which is increasing in urban area, is considered in MobCall. And also, user's movements on highway are considered in MobCall. The object-oriented simulation platform, C++SIM, is used to implement MobCall. Using MobCall, the accumulated number of calls in residential and commercial regions, the handoff rate with respect to traffic sources of Seoul, the handoff rate on highway, and the handoff rate according to the call duration are presented. MobCall enables the simulation of dynamic handoff buffering and functional entity control of one base station according to the changes in user's calling pattern at the design phase. Also, when a new town is under construction by a detailed plan, MobCall is used to design the mobile network with regional characteristics and user mobility considered.

• Journal of Communications and Networks
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• v.8 no.2
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• pp.175-181
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• 2006

This paper addresses an in-depth analysis of the stratosphere-to-Earth co-channel interference produced by high-altitude platforms (HAPs) and proposes a new methodology for the evaluation of its impact to terrestrial systems in terms of fractional degradation in performance, taking into account parameters such as HAP's mobility, realistic distribution of azimuth and elevation angles of the terrestrial microwave links (TMLs), and gradual high-altitude platform network (HAPN) loading. Simulations performed for different HAPN configurations, prove that the implementation of the methodology proposed, may lead to a more efficient use of the spectrum shared between the two services.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.756-761
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• 2010

Bimodal trams are run by a guidance system and combine the functions of buses and trains. The trams have been highlighted as an alternative means of public transportation due to their accessibility, mobility, and arrival accuracy. While bimodal trams can be implemented on existing roads or by road expansion, with the narrow road conditions in Korea, studies must be performed in advance on suitable lane and platform locations and the exclusivity of lane use. This paper proposes plans for the location of bimodal tram lanes and platforms, whether in the median or at the road’s edge. In addition, methods of efficient bimodal tram operation are discussed, including the implementation of exclusive tram lanes.