• IE interfaces
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• v.12 no.4
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• pp.586-594
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• 1999

This paper introduces a production scheduling system for the block assembly shop in a shipbuilding company. We are to make a schedule for the assembly shop and related subassembly production shop. The objectives of the scheduling system are balancing of the workload of the subassembly shops as well as the assembly shop. There are a number of technological and resource constraints including assembly space restriction which is most important and critical resource in the shop. It is very hard and time consuming to consider the two problems, the workload balancing and the spatial allocation problem, simultaneously, and hence, we analyze the two problems independently. The first problem has already been introduced(고시근, 1996), and the overall appearance of the system and the spatial allocation algorithm are presented in this paper.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.643-648
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• 2005

The planning process for roadway construction involves a large amount of information on design, construction methods, quantities, unit costs, production rates, and site conditions. Therefore, it is very important to acquire, manage, and process the necessary information efficiently to produce a rigorous construction plan. GIS (Geographic Information System) is a very effective tool for integrating and managing various types of information including spatial and non-spatial data required for roadway construction planning. This paper proposes a GIS-based system for improving roadway construction planning with its 'Interactive Space Scheduling' and 'Operation Level Planning' functions. The proposed system can assist construction planners in a unique way by integrating design and construction information and creating modularized design elements for space scheduling in real time. It is expected that the proposed system could improve the efficiency of roadway construction planning.

• Journal of the Korea Society for Simulation
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• v.20 no.1
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• pp.19-28
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• 2011

The safety applications based on the IEEE 802.11p, periodically transmit the safety-related information to all surrounding vehicles with high reliability and a strict timeline. However, due to the high vehicle mobility, dynamic network topology and limited network resource, the fixed beacon scheduling scheme excess delay and packet loss due to the channel contention and network congestion. With this motivation, we propose a novel beacon scheduling algorithm referred to as spatial-aware(SA) beacon scheduling based on the spatial context information, dynamically rescheduling the beaconing rate like a TDMA channel access scheme. The proposed SA beacon scheduling algorithm was evaluated using different highway traffic scenarios with both a realistic channel model and 802.11p model in our simulation. The simulation results showed that the performance of our proposed algorithm was better than the fixed scheduling in terms of throughput, channel access delay, and channel load. Also, our proposed algorithm is satisfy the requirements of vehicular safety application.

• Journal of Communications and Networks
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• v.13 no.4
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• pp.400-407
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• 2011

Various air indexing and data scheduling schemes for wireless broadcast of spatial data have been developed for energy efficient query processing. The existing schemes are not effective when the clients' data access patterns are skewed to some items. It is because the schemes are based on flat broadcast that does not take the popularity of the data items into consideration. In this paper, thus, we propose a data scheduling scheme letting the popular items appear more frequently on the channel, and grid-based distributed index for non-flat broadcast (GDIN) for window query processing. The proposed GDIN allows quick and energy efficient processing of window query, matching the clients' linear channel access pattern and letting the clients access only the queried data items. The simulation results show that the proposed GDIN significantly outperforms the existing schemes in terms of access time, tuning time, and energy efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12A
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• pp.1209-1216
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• 2008

In order to maximize spectrum efficiency and data rate MIMO(Multiple Input Multiple Output) is adopted to wireless system. OFDM-based WiMAX and LTE accommodate MIMO as mandatory technology. STC(Space Time Coding) and SM(Spatial Multiplexing) are used in downlink while in uplink C-MIMO(Collaborative MIMO) is used to improve data throughput. In this paper conventional pairing schemes, RPS(Random Pairing Scheduling) and DPS(Determinant Pairing Scheduling) are analyzed. From the analysis the performance of DPS algorithm is better than that of RPS because DPS measures orthogonal factor between paired users. However, there are potential problems such as hardware complexity and performance. To overcome the issues Power-Based Scheduling(PBS) algorithm is proposed for C-MIMO. PBS can provide higher performance compared to RPS and dramatically reduce hardware complexity compared to DPS

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.106-110
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• 2004

In any large heavy industry like that of ship building, there exist a lot of complications for the arrangement of building blocks optimally for the minimal space consumption. The major problem arises at yard because of laxity in space for arranging the building blocks of ship under construction. A standardized erection sequence diagram is generally available to provide the prioritised erection sequence. This erection sequence diagram serves as the frame work. In order to make a timely erection of the blocks a post plan has to be developed so that the blocks lie in the nearest possible vicinity of the material handling devices while keeping the priority of erection. Therefore, the blocks are arranged in the pre-erection area. This kind of readiness of blocks leads to a very complex problem of space. This arises due to the least available space leading to an urgent need of an availability of intelligent spatial schedule without compromising the rate of production. There exists two critical problems ahead namely, the spatial occupation layout of pre-erection area and the emptying pattern in the spatial vicinity. The block shape is assumed be rectangular. The related input data's are the dates of erection (earliest as well as the latest), geometrical parameters of block available on pre-erection area, slack time and the like.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.565-568
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• 2003

Roadway construction planning processes involve a large amount of information on design, construction methods, quantities, unit costs, and production rates. GIS (Geographic Information System) is a strong tool for integration and managing various types of information such as spatial and non-spatial data required for roadway construction planning. This paper proposes a GIS-based system for improving roadway construction planning with its 'Spatial Analysis' and 'Visualization' functions. The proposed system cail help construction planner make a proper decision in a unique way by integrating design information and construction information within the system and creating design element modules for space scheduling purposes in real-time with its 'Interactive Planning' function.

• IE interfaces
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• v.24 no.1
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• pp.78-86
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• 2011

To mitigate space restriction and to raise productivity, some shipbuilding companies use floating-docks on the sea instead of dry-docks on the land. In that case, a floating-crane that can lift very heavy objects (up to 3,600 tons) is used to handle the blocks which are the basic units in shipbuilding processes, and so, very large blocks (these are called the mega-blocks) can be used to build a ship. But, because these mega-blocks can be made only in the area near the floating-dock and beside the sea, the space is very important resource for the process. Therefore, our problem is to make an efficient spatial schedule for the mega-block assembly yard. First of all, we formulate this situation into a mathematical model and find optimal solution for a small problem using a commercial optimization software. But, the software could not give optimal solutions for practical sized problems in a reasonable time, and so we propose a GA-based heuristic algorithm. Through a numerical experiment, finally, we show that the spatial scheduling algorithm can provide a very good performance.

• Spatial Information Research
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• v.9 no.1
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• pp.15-30
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• 2001

Solid waste collection service is viewed as one of the most important public services in urban area. The purpose of this study is to apply the GIS based regional partitioning and arc routing methods for solid waste collection districting and vehicle routing-scheduling in order to provide waste collection service more efficiently. In this study, solid waste deposit sites are derived from the centroid of each building and the amount of solid waste is deduced based on the number of households and establishments. The regional partitioning procedure is performed based on waste collection zones which are constructed from waste deposit sites. The result of this study shows that solid waste collection districts which are delineated by regional partitioning method are able to increase efficiencies and cut costs in performing solid waste collection services. Also the output of vehicle-scheduling from the analysis of arc routing may provide more efficiently and quickly manage the scheduling of the residential solid waste collection routes, reducing costs with minimal deadheading costs. Therefore, the application of GIS based on regional partitioning and arc routing methods would be very useful to construct a solid waste management system by supplying the important and flexible informations for solid waste collection districts and vehicle routing-scheduling for waste collection.

• Journal of Communications and Networks
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• v.8 no.4
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• pp.401-409
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• 2006

Orthogonal frequency division multiplexing (OFDM) and multiple input multiple output (MIMO) technologies provide additional dimensions of freedom with spectral and spatial resources for radio resource management. Multi-dimensional radio resource management has recently been identified to exploit the full dimensions of freedom for more flexible and efficient utilization of scarce radio spectrum while provide diverse quality of service (QoS) guarantees. In this work, a multi-dimensional radio resource scheduling scheme is proposed to achieve above goals in hybrid orthogonal frequency division multiple access (OFDMA) and space division multiple access (SDMA) systems. Cochannel interference (CCI) introduced by frequency reuse under SDMA is eliminated by frequency division and time division between highly interfered users. This scheme maximizes system throughput subjected to the minimum data rate guarantee. for heterogeneous users and transmit power constraint. By numerical examples, system throughput and fairness superiority of the our scheduling scheme are verified.