• The Journal of the Korea Contents Association
• /
• v.5 no.4
• /
• pp.245-253
• /
• 2005

The multimedia ad hoc wireless network is quite an attractive issue since it offers a flexible solution to enable delivery of multimedia services to mobile end users without fixed backbone networks. However, with the unique design challenges of ad hoc wireless networks, it is a non-trivial issue to provide bounded delay guarantee, with fair share of resources. In this paper, we proposed distributed implementation of the delay guaranteed fair queueing (DGFQ) scheme in multimedia ad hoc wireless networks. Through the the results of performance evaluation, we can conclude that DGFQ also performs well to control bounded delay in multimedia ad hoc wireless networks.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.5D
• /
• pp.839-848
• /
• 2006

Korea has become the 5th country to own and operate the high speed railroad in 2004. However, there were many difficulties until Koreans enjoy the first bullet train service with the average hourly speed of 300km. The high speed railroad requires elevated quality standards differently from the traditional railways. In addition to the technical difficulties, the construction project itself was an unpleasant case with huge delays and cost overruns mainly due to the lack of experiences, deficiency of owner$^{\circ}{\O}$s role, and increase of public resistances triggered by environmental concerns. This paper analyzes the reasons for delays on this mega-project. With respect to the characteristics of the whole project level, it is very complicated/linear project, whose total length is around 412 km with the composition of various sections in the route of the railway which have basically different conditions. For that reason, the analysis is performed in both macro and micro level. First, macroscopic analysis is performed to find critical subdivisions in the railway route that induces the significant delay in the opening due date. Then, microscopic analysis is followed to quantify the causes and effects of delays focused on these critical subdivisions in more detailed way. Finally, this paper provides lessons learned from this project to avoid the decisive delays in performing the similar large-scaled projects.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.286-289
• /
• 2003

In turn-key projects, escalation of cost by design errors is not allowed because a contractor prepares the design. Therefore, cost escalation by design errors results in increasing the cost of the prime contractor. The rate of profit decreases finally. In addition, design errors bring not only schedule delay but also serious quality problem by unknown errors. This study tries to dissolve problems, that of cost increase. process delay and a falling-off in quality by investigating cause of design errors and presenting a scheme for reducing design errors.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.44 no.1
• /
• pp.25-32
• /
• 2007

In this paper, a new method for first order plus dead time(FOPDT) model identification is proposed, which can identity multiple points on a process step response in terms of classification of time response. The process input and output to the test are decomposed into the transient part and the steady-state part. The steady-state part express one FOPDT model and the transient part express variously FOPDT model using least square estimation method. The optimum parameter tuning algorithm for PID controller of the Smith Predictor is proposed through ITAE as performance index. The Simulation results show the validity and improvement of performance for various processes.

• Journal of Korea Multimedia Society
• /
• v.9 no.2
• /
• pp.197-207
• /
• 2006

When the latency of a flow in a fair packet scheduler, which is determined by its rate, violates its required delay bound, the scheduler should reduce the latency with even raising the rate being reserved for the flow. The excessively reserved rate win enforce some outgoing link bandwidth be lost. This loss can not be, unfortunately, evaluated by the three metrics of latency, fairness and implementation complexity used in previous works. This paper is aimed to first introduce the metric of bandwidth utilization to investigate the bandwidth loss in a scheduler and then evaluate the timestamp based schedulers in terms of the bandwidth and payload utilizations. The results show that the bandwidth utilization increases with loosing the required delay bound and, in particular, schedulers with the latency property of WFQ have much better payload utilization by up to 50% than that in the SCFQ one.

• Proceedings of the CALSEC Conference
• /
• 2001.02a
• /
• pp.247-256
• /
• 2001

● 다중 플랜트로 구성된 공급사슬에서 각 부품의 공정순서 결정 ● 공정별 장비선정 ● 납기 지연시간 최소화를 위한 일정계획을 수립(중략)

• The Optical Journal
• /
• v.13 no.1 s.71
• /
• pp.18-23
• /
• 2001

이번 호는 제조에서 가장 중요한 부분인 공정관리를 다룬다. 공정관리는 품질, 원가, 수량을 잘 조절해 납기 내에 생산하기 위해 사람, 기계, 재료를 가장 경제적으로 운용하는 것을 말한다. 공정관리가 제대로 되지 않으면 생산가동률이 저하되는 동시에 원가는 올라가고 납기일은 지연돼 막대한 손실을 발생시킨다는 것은 현장 근무자들이 심각하게 느끼고 있을 것이다. 제대로 공정 관리가 되기 위해서는 기계배치, 운반계획, 일정계획, 인원계획 등의 기초자료로 사용되는

• Proceedings of the Korean Information Science Society Conference
• /
• 2001.10c
• /
• pp.1-3
• /
• 2001

VLSI칩 내부애서 길이가 긴 도선을 통해서 데이터를 보낼 메, 누화(crosstalk)의 영향으로 데이터 값에 따라 지연시간이 변한다. 그리고 지연시간의 변화폭도 CMOS공정이 초미세화됨에 따라서 더욱 커진다. 본 논문에서는 지연시간을 줄이기 위해서, 데이터 코딩을 이용하여 가장 긴 지연시간을 피하는 데이터 초기화에 기반한 단일선 4-위상 프로토롤을 제안한다. 제안된 프로토콜을 긴 도선에 적용함으로써 도선에서의 최대 지연시간을 최대 49% 감소시킨다.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.509-512
• /
• 2003

The Critical Path Method(CPM) is an effective tool used for planning and scheduling. One of strong point in the CPM is what can calculate float. Float is able to prolong without having an effect on overall schedule of project, however concept and scope about ownership is not definite, because it is a by-product of project. Thus participants have had many dispute in using float because of their interests. In recent years, a few theories have evolved in an attempt to solve this problem. But the prior research did not make a reasonable distribution of float because their criteria of distribution was based on ratio for total project time. Actually, an application of float is achieved by participant's delay risk. Therefore. this paper proposes criteria for float distribution using delay risks, and the framework for the assessment of the delay risks.

• Journal of Korea Multimedia Society
• /
• v.9 no.3
• /
• pp.323-332
• /
• 2006

Fair packet scheduling algorithms supporting quality-of-services of real-time multimedia applications can be classified into the following two schemes in terms of the reference time used in calculating the timestamp of arriving packet; the Finish-Time (FT) and Start-Time (ST) schemes. The FT scheme, used in most schedulers, that has the property of an inversely rate-proportional latency is suitable to support various delay bounds because it can adjust the latency of a flow with raising the flow's reserved rate. However, the scheme may incur some bandwidth loss due to excess rate reservation. Meanwhile, although the ST scheme does not suffer from the bandwidth loss, it is hard to support multiple delay bounds because of its latency property relying on the number of flows. This paper is devoted to propose a ST scheme based scheduler to effectively support multiple delay bounds and analyze its performance comparing to the FT scheme based scheduler. The comparison results show that the proposed scheduler gives better utilization by up to 50%.