• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.57-66
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• 2010

In this paper, we propose the reliability constrained resource allocation scheduling algorithm in cellular network for uplink transmission, where uplink transmission is supported via packet switching schemes without the dedicated uplink circuit links. We evaluate the performance of the proposed algorithm, and compared with the conventional works to identify the pros and cons. The proposed uplink scheduling algorithm is to satisfy the constraints requirements of the MTC services which is considered as the core technology for future mobile wireless networks. It is different to conventional works which target to maximize the link capacity. The proposed algorithm provides reliable uplink transmission independent to the location and the quality of the wireless link of the mobile terminal. Based on the performance evaluation results, we conclude that the proposed method provides enhanced reliability performance than conventional works.

• Journal of Navigation and Port Research
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• v.29 no.5 s.101
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• pp.415-420
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• 2005

LMTT (Linear Motor-based Transfer Technology) is the horizontal transfer system for yard automation, which has been proposed to take the place of AGV (Automated Guided Vehicle) in the maritime container terminal. The system is based on PMLSM (Permanent Magnetic Linear Synchronous Motor) that consists of stator modules on the rail and shuttle car. It is desirable to reduce the weight of LMTT in order to control the electronic devices with minimum energy. In this research, structural optimization for a mover of shuttle car is performed to minimize the weight satisfying design criteria. The objective function is set up as weight. On the contrary, the design variables are transverse, longitudinal and wheel beams' thicknesses and its height, and the constraints are considered as strength and stiffness.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.147-152
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• 2006

Nowadays, the redevelopment of the conventional pier in Busan port has been one of top issues on Busan port. Busan Port Authority has already launched a research project on that and the Master Plan undergoing. However, the conventional pier is still booming one for small vessels providing feeder service to and from Busan port and both Japanese ports and Chinese ones. Accordingly, there are several terminal operation companies(TOC) and union workers which make might be a major obstacle for the redevelopment. Furthermore, it has been said that alternative pier is necessary before starting redevelopment. Under such circumstance this paper tries to review the major limitations and provide some thought for the solution.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.1
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• pp.21-30
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• 2021

Mid-course trajectory of the missiles equipped with seeker should be designed to detect target within FOV of seeker and to maximize the maneuverability at the point of transition to terminal guidance phase. Because the trajectory optimization problems are generally hard to obtain the analytic solutions due to its own nonlinearity with several constraints, the various numerical methods have been presented so far. In this paper, mid-course trajectory optimization problem for boost-glide missiles is calculated by using SOCP (Second-Order Cone Programming) which is one of convex optimization methods. At first, control variable augmentation scheme with a control constraint is suggested to reduce state variables of missile dynamics. And it is reformulated using a normalized time approach to cope with a free final time problem and boost time problem. Then, partial linearization and lossless convexification are used to convexify dynamic equation and control constraint, respectively. Finally, the results of the proposed method are compared with those of state-of-the-art nonlinear optimization method for verification.

• Journal of Ocean Engineering and Technology
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• v.36 no.3
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• pp.181-193
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• 2022

This study presents a mission management technique that is a key component of underwater docking system used to expand the operating range of autonomous underwater vehicle (AUV). We analyzed the docking scenario and AUV operating environment, defining the feasible initial area (FIA) level, event level, and global path (GP) command to improve the rate of docking success and AUV safety. Non-holonomic constraints, mounted sensor characteristic, AUV and mission state, and AUV behavior were considered. Using AUV and docking station, we conducted experiments on land and at sea. The first test was conducted on land to prevent loss and damage of the AUV and verify stability and interconnection with other algorithms; it performed well in normal and abnormal situations. Subsequently, we attempted to dock under the sea and verified its performance; it also worked well in a sea environment. In this study, we presented the mission management technique and showed its performance. We demonstrated AUV docking with this algorithm and verified that the rate of docking success was higher compared to those obtained in other studies.

• Journal of Broadcast Engineering
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• v.18 no.6
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• pp.895-910
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• 2013

Multi-screen service is a service that consumes more than one media in a number of terminals simultaneously or discriminately. This multi-screen service has become useful due to distribute of smart TV and terminals. Also, in case of hybrid broadcasting environment that is convergence of broadcasting and communication environment, it is able to provide various user experience through contents consumed by multiple screens. In hybrid broadcasting environment, scene composition technology can be used as an element technology for multi-screen service. Using scene composition technology, multiple media can be consumed complexly through the specified presentation time and space. Thus, multi-screen service based on the scene composition technology can provide spatial and temporal control and consumption of multiple media by linkage between the terminals. However, existing scene composition technologies are not able to use easily in hybrid broadcasting because of applicable environmental constraints, the difficulty in applying the various terminal and complexity. For this problems, HTML5 can be considered. HTML5 is expected to be applied in various smart terminals commonly, and provides consumption of diverse media. So, in this paper, it proposes the scene composition and multi-screen service technology based on HTML5 that is expected be used in various smart terminals providing hybrid broadcasting environment. For this, it includes the introduction in terms of HTML5 and multi-screen service, the method of providing information related with scene composition and multi-screen service through the extention of elements and attributes in HTML5, media signaling between terminals and the method of synchronization. In addition, the proposed scene composition and multi-screen service technology based on HTML5 was verified through the implementation and experiment.

• Journal of Broadcast Engineering
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• v.8 no.4
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• pp.325-338
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• 2003

Video adaptation in response to dynamic resource conditions and user preferences is required as a key technology to enable universal multimedia access (UMA) through heterogeneous networks by a multitude of devices In a seamless way. Although many adaptation techniques exist, selections of appropriate adaptations among multiple choices that would satisfy given constraints are often ad hoc. To provide a systematic solution, we present a general conceptual framework to model video entity, adaptation, resource, utility, and relations among them. It allows for formulation of various adaptation problems as resource-constrained utility maximization. We apply the framework to a practical case of dynamic bit rate adaptation of MPEG-4 video streams by employing combination of frame dropping and DCT coefficient dropping. Furthermore, we present a descriptor, which has been accepted as a part of MPEG-21 Digital Item Adaptation (DIA), for supporting terminal and network quality of service (QoS) in an interoperable manner. Experiments are presented to demonstrate the feasibility of the presented framework using the descriptor.