• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5B
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• pp.498-508
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• 2009

In wireless mobile environments, large bandwidth and high QoS (Quality of Service) are recently required to support the increased demands for multimedia services. LTE (Long Term Evolution) is one of the promising solutions for the next generation broadband wireless access systems. To efficiently use downlink resource and effectively support QoS, packet scheduling algorithm is one of the important features in LTE system. In this paper, we proposed DAPS (Delay-Aware Packet Scheduling) algorithm to consider QoS requirements of delays for various traffic classes as well as channel condition and fairness. To reflect delay experiences at scheduling instance, DAPS observes how queue waiting time of packet is closed to maximum allowable delay. The simulation results show that the DAPS algorithm yields better performance for delay experience by increasing the number of transmitted packets with satisfying the required delay time compared with existing scheduling algorithms.

• Journal of Technology Innovation
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• v.16 no.1
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• pp.107-139
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• 2008

We studied how to achieve successful implementation of massive research and development projects requiring collaboration among industries, universities and government-supported research institute. We have set up an engineering process innovation model to be deemed most adequately for all practical purposes, relying on the theoretical studies on the merits and analysis of the effect of the information system based on Milestone Management, Work Breakdown Structures and Web, which is known to be effective for research project (schedule) management and the objective management, and implemented a real-world web-based project objective management system. After a review of various R & D Project Schedule Management methods, we found that this information system was very compatible with project objective management. This project objective management information system carries out research and development projects effectively and efficiently, getting together in cyber-space and sharing information, and has been equipped with an Early Warning Subsystem to allow for pre-analysis and timely response to potential problems arising from the course of the project. The system also contains an Executive Information System that in real time, automatically provides the management information required by managers with the rate of project progress (achievement, fulfillment and delay). Lastly, actual progress can be cross-checked through both on-line objective management on the web-based information system and design review meeting held on site, to improve the efficiency and validity of the information system. Moreover, overall effect was analyzed through questionnaires on how well the system and generated information meet requirements and on the ultimate impact of the system upon objective management and communication. The questionnaire on the system effect revealed that the information system was useful to objective management and communication, and that the quality of the system was more than acceptable as well.

• Journal of Construction Engineering and Project Management
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• v.4 no.1
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• pp.29-36
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• 2014

Tunnelling has become a preferred method of construction for road and highway projects in countries with a lot of hilly slope geological conditions such as found in Malaysia. However the construction works of a tunnelling project are usually complicated and costly, which consequently impose great risks to the parties involved. This paper identifies the key significant risks and sub-risks for tunnelling construction projects in Malaysia through a case study. Interview has been used as the solitary means to determine the significant risks from contractor's eleven key project personnel who were directly involved in the tunnelling construction such as consultant, construction manager and tunnel engineers. The importance of the risks identified is then prioritised and ranked via the Analytic Hierarchy Process (AHP)'s pairwise comparison approach to determine their criticality towards a successful delivery of project. As a result, three key risks have been identified as significant for the tunnelling case study project, namely health and safety, cost overrun in construction and time overrun in construction. Two sub-risks each of the latter categories, which are cost underestimation and unforeseen events (cost overrun in construction) as well as plant and machinery failure and delay in material delivery (time overrun in construction), have occupied the top five overall risk ranking.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.383-387
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• 2003

Construction project has many problem such as delay of the appointed date delivery, over budget, wether and site conditions. When several activities are influenced by the same factor, their duration may be delayed. This paper deals with the problem of construction duration estimating and schedule variation on the construction project. The theory of constraints technique for project management is referred to 'Critical Chain' technique. This paper shows optimal scheduling plan and time management technique, used probability construction duration estimating and scheduling buffer based on the critical chain project management.

• Plant Journal
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• v.5 no.2
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• pp.62-67
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• 2009

The capability of design and engineering of global EPC companies has long been equalized through past similar construction experiences. Among various key factors in the success of EPC project, the capability of engineering is considered to be the most important factor since the engineering is preceding activities of EPC contract. The failure of engineering may adversely affect the subsequent procurement & construction activities and in turn may cause cost overrun or schedule delay. Therefore, an EPC company needs to continue to improve the engineering capabilities for the success of project. The engineering capabilities can be further improved if the EPC company should prevent recurrence of similar design faults that were previously committed. This study is intended to present how to make the most of the failure examples from previous projects towards a success of project. Failure is but a stepping stone to success. The EPC company can obtain useful lessons from the analysis of past failure examples.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.379-382
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• 2001

In domestic construction industry, time and cost has been managed separately in most cases. Usually projects are managed focused on cost, so time is not yet managed systematically. Project performance in these managemental situation can not be assessed correctly. This would cause project delay, cost overrun, productivity loss. Therefore it is needed to adopt earned value concept, an approach used in the management and control of project costs and schedules. Using this EV concept through time-cost integration, project can be managed properly based on the consistency, predictability, and reliability of the performance data. This paper proposed time and cost integration process, proper PMT method, and practical performance management model through time and cost integration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.252-255
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• 2004

반도체는 high integrated, high speed, low power를 위하여 design 뿐만 아니라 재료 측면에서도 많은 변화를 가져오고 있으며, RC delay time을 줄이기 위하여 Al 배선보다 비저항이 낮은 Cu와 low-k material 적용이 그 대표적인 예이다. 그러나, Cu 배선의 경우 dry etching이 어려우므로, 기존의 공정으로는 그 한계를 가지므로 damascene 또는 dual damascene 공정이 소개, 적용되고 있다. Damascene 공정은 절연막에 photo와 RIE 공정을 이용하여 trench를 형성시킨 후 electrochemical plating 공정을 이용하여 trench에 Cu를 filling 시킨다. 이후 CMP 공정을 이용하여 절연막 위의 Cu와 barrier material을 제거함으로서 Cu 배선을 형성하게 된다. Dual damascene 공정은 trench와 via를 동시에 형성시키는 기술로 현재 대부분의 Cu 배선 공정에 적용되고 있다. Cu CMP는 기존의 metal CMP와 마찬가지로 oxidizer를 이용한 Cu film의 화학반응과 연마 입자의 기계가공이 기본 메커니즘이다. Cu CMP에서 backside pressure 영향이 uniformity에 미치는 영향을 살펴보았으며, electrochemical plating 공정에서 발생하는 hump가 CMP 결과에 미치는 영향과 dishing 결과를 통하여 그 영향을 평가하였다.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.144-150
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• 2005

After the historic opening of the first section of KTX(Korea Train eXpress), it has been made changes three times in a plan to pass through cities of Daejeon, Daegu in the construction of the high speed train's second section(underground${\to}$ on ground${\to}$ under ground${\to}$ on ground). Thereafter, it has been repeatedly argued that the plan to pass through underground caused many problems such as prevention of an accident in tunnel, the difficulty of maintainence, the disadvantage of passengers' moving line. Thus construction on ground plan is coming up again with relation to the interest among local people. There have been lots of national budget loss, construction period delay in this project and people hardly trust policies about national project and nor do engineers. It will be presented that the railway line which is accorded with the characteristics of region, an agreement with local communities about national project, the reasonable procedure to determine how to pass through cities, resolve the conflict among neighborhood, and the role of engineers.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.622-624
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• 2015

As uncertain factors are latent in a construction project by nature, a change order occurs frequently. The occurrence of change orders in construction projects conducted during construction phase is known to cause unexpected negative impacts such as cost overrun, schedule delay, quality problem, and claims in the post-process. Thus, an efficient management method is necessary to prevent and minimize change orders during construction phase when they occur frequently. This paper analyzed the causes of change orders and the impact factors that occur during the construction phase of a construction project and suggested a direction for change order database building.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.638-642
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• 2005

This paper presents incentive application strategies and delay prevention strategies as schematic approaches to improve time performance of highway construction contracts. This research recognizes the importance of improving time performance during highway construction. Strategic solutions of the most core issues on time performance incentive contracting are identified. The suggested incentive application strategies develop criteria for applying time classification to projects, for assigning project time classifications to contractors and designers, and for determining appropriate incentive values in A (cost) + B (time cost) and other performance incentive contracts. The suggested delay prevention strategies develop criteria for determining the appropriate subsurface utility engineering (SUE) level and to develop best practices for avoiding utility relocation delays. A schematic approach for each strategy is developed. This paper also introduces current incentive contracting practices in Florida. The researchers obtained the information from experienced persons in the highway construction industry, including key highway contractors, designers, and Department of Transportation (DOT) and Federal Highway Administration (FHWA) personnel. The major focus of this research is to develop strategies and suggest approaches to improve time performance of highway construction contracts. For future study, practical tools to facilitate implementation of the suggested strategies should be developed, so that the criteria, implementation processes, and best practices developed may contribute to the current industry-wide effort to improve time performance.