• Korean Journal of Construction Engineering and Management
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• v.12 no.6
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• pp.31-41
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• 2011

Since the cases of time extension have continuously transpired in the public construction project, the potential of economical loss and claims is increasing because the concerned parties such as an owner or a contractor have not properly performed their own responsibility for time extension. One of the main reasons is that the present planning and scheduling do not support the method to apportion the proper responsibility to the right party. This problem has repeatedly led to time extension and made it difficult for the concerned parties to perform the responsibility for time extension. In order to overcome this problem, a framework of delay administration is required as the method to apportion the proper responsibility to the right party. To solve this problem, this paper aimed to develop the conceptual model and prototype system as the practical method to administrate delay causation. Furthermore, the verification result for the reliability and applicability throughout the case studies on real construction projects shows that the conceptual model and prototype system developed would help efficiently to administrate the delay causation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3B
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• pp.161-167
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• 2007

In this paper, we evaluate the capacity of voice over internet protocol (VoIP) services over high-speed downlink packet access (HSDPA), in which frame-bundling (FB) is incorporated to reduce the effect of relatively large headers in the IP/UDP/RTP layers. Also, a modified proportional pair (PF) packet scheduler design supporting for VoIP service is provided. The main focus of this work is the effect of FB on system outage based on delay budget in radio access networks. Simulation results show that VoIP system performance with FB scheme is highly sensitive to delay budget. We also conclude that HSDPA is attractive for transmission of VoIP if compared to the circuit switched (CS) voice that is used in WCDMA (Release'99).

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.2
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• pp.1-8
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• 2011

An underwater robot S/W framework consists of various sub-modules such as sensory data processing module, thruster control module, cognition module and behavior control module. Performance of a robot is determined by not only the efficiency of algorithms used but also effectiveness of their implementations. One most important factor of the effective implementation is the efficiency of data sharing module, as it transmits signals and data between the sub-modules and thus is directly related to the cycles of sensing and control The ideal data sharing module enables immediate access to any data source irrespective of system configurations. In reality, however, there are lots of obstacles including limitation of processing capacity of source modules, delay over network, and scheduling latency of operating systems. The paper proposes a new data sharing architecture and programming models to effectively handle such obstacles in implementation of underwater S/W framework on a small scale distributed computing system.

• Journal of Korea Multimedia Society
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• v.7 no.7
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• pp.886-895
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• 2004

In this paper, we propose the dynamic allocation scheme of the CPU bandwidth to efficiently integrate and schedule these tasks in the same system, where multimedia tasks and hard real-time tasks can coexist simultaneously. Hard real-time tasks are guaranteed based on worst case execution times, whereas multimedia tasks modeled as soft real-time tasks are served based on mean parameters. This paper describes a server-based allocation scheme for assigning the CPU resource to two types of tasks. Especially for MPEG video streams, we show how to dynamically control the fraction of the CPU bandwidth allocated to each multimedia task. The primary purpose of the proposed method is to minimize the mean tardiness of multimedia tasks while satisfying the timing constraints of hard real-time tasks present in the system. We showed through simulations that the tardiness experienced by multimedia tasks under the proposed allocation scheme is much smaller than that experienced by using other scheme.

• Journal of Navigation and Port Research
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• v.33 no.8
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• pp.555-562
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• 2009

At container terminals, a major measurement of productivity can be work-efficiency in quay-side. At the apron, containers are loaded onto the ship and unloaded to apron by Q/C(Quay Crane). For improving the productivity of quay crane, the more efficient Y/T(Yard Tractor) operation method is necessary in container terminals. Between quay-side and yard area, current transferring methods is single-cycling which doesn't start loading unless it finishes unloading. Dual-cycling is a technique that can be used to improve the productivity of quay-side and utility of yard tractor by ship loading and unloading simultaneously. Using the dual-cycling at terminals only necessitates an operational change without purchasing extra equipment. Exactly, Y/T operation method has to be changed the dedicate system to pooling system. This paper presents an efficient ship loading and unloading plan in container terminals, which use the dual-cycling. We propose genetic and tabu search algorithm for this problem.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.7
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• pp.666-673
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• 2008

To construct the accurate radio satellite navigation system, the efficient communication each satellite with the ground station is very important. Throughout the communication, the orbit of each satellite can be corrected, and those information will be used to analyze the satellite satus by the operator. Since there are limited resources of ground station, the schedule of antenna's azimuth and elevation angle should be optimized. On the other hand, the satellite in the medium earth orbit does not pass the same point of the earth surface due to the rotation of the earth. Therefore, the antenna pass schedule must be updated at the proper moment. In this study, Q learning approach which is a form of model-free reinforcement learning and genetic algorithm are considered to find the optimal antenna schedule. To verify the optimality of the solution, numerical simulations are conducted.

• Korean Journal of Construction Engineering and Management
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• v.6 no.6 s.28
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• pp.181-192
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• 2005

Labor work information can be converted into the useful construction information in an effort to analyze project status, measure performance, and design a new similar project plan. The labor work information can also be used to make productivity data, which can be used to analyze the relationship between 'as planned' and 'as built' in scheduling management of a project, and to calculate 'percent completion' as well as analyzing delay cause. It is require to effectively collect the labor work information base on the activities. In general, current project management heavily depends on the experience and judgment of project managers, according to the work progress. However, relying on the oかy experience and judgment of the project managers might deteriorate the transparency or reliability of the collected labor work information. The purpose of this research is thus to develop a computer-based system for monitoring the work information generated by labors input in activities using PDA and Barcode technologies, and to propose a application method of the productivity data for effective project management.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12C
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• pp.1164-1174
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• 2007

Antenna selection based MIMO schedulers are proposed to achieve the optimal performance with low complexity in uplink multiuser MIMO/FDD system. In this paper, three heuristic schedulers are proposed to approach the optimal performance which is achieved by the optimal Brute-Force Scheduler. Two search methods called sub-set and full-set way are also discussed to set up the antenna channels to be the candidates of the scheduler. Simulation results show that the sum rate and BER performance of the proposed CSS and SOAS schemes are about the same to that of the brute-force scheduler with affordable complexity, while RC-SOAS with further reduced complexity achieves almost the optimal performance in the case of small number of antennas. Moreover, the complexity can be additionally reduced by the sub-set search method when the number of transmit and receive antennas are 2 respectively, which is applicable in the realistic systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1844-1850
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• 2016

The bilateral filter can reduce the noise while preserving details computing the filtering output at each pixels as the average of neighboring pixels. In this paper, we propose a real-time system based on window division. Overall performance is increased due to the parallel architectures which computes five rows in the kernel window simultaneously but with pipelined scheduling. We consider the tradeoff between the filter performance and the hardware cost and the bit allocation has been determined by PSNR analysis. The proposed architecture is designed with verilogHDL and synthesized using Dongbu Hitek 110nm standard cell library. The proposed architecture shows 416Mpixels/s (397fps) of throughput at 416MHz of operating frequency with 132K gates.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.103-103
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• 2000

In this paper to cope with the reduction of products life-cycle as the variety of products along with the various demands of consumers, a virtual simulator is developed to make the changeover of manufacturing line efficient to embody a virtual simulation similar to a real manufacturing line. The developed virtual simulator can design a layout of a factory and make the time scheduling. Every factory has one simulator so that one product can be manufactured in the factories to use them as virtual factories. We suggest a scheme that heightens the agility to the diversity of manufacturing models by making the information of manufacturing lines and products models to be shared. The developed unit simulator can construct a proper virtual manufacturing line along with the required process of products using several kinds of operator and work cell. A user with the simulator can utilize an interface that makes one to manage the separate task process for each manu(acturing module, change operator components and work cells, and easily teach tasks of each task module. The developed simulator was made for users convenience by Microsoft Visual C++ 6.0 that can develop a program supplying graphic user interface environment and by OpenGL of the Silicon Graphics as a graphic library to embody 3D graphic environment. Also, we show that the simulator can be used efficiently for the agile manufacturing by the communication among the factories being linked by TCP/IP and a hybrid database system made by a hierarchical model and a relational model being developed to standardize the data information.