• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.1922-1931
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• 1999

A multicast traffic’s feature is the function of providing a point to multipoints cell transmission, which is emerging from the main function of ATM switch. However, when a conventional point-to-point switch executes a multicast function, the excess load is occurred because unicast cell as well as multicast cell passed the copy network. Additionally, due to the excess load, multicast cells collide with other cells in a switch. Thus a deadlock that losses cells raises, extremely diminishes the performance of switch. An input queued switch also has a defect of the HOL (Head of Line) blocking that less lessens the performance of the switch. In the proposed multicast switch, we use shared memory switch to reduce HOL blocking and deadlock. In order to decrease switch’s complexity and cell's processing time, to improve a throughput, we utilize the method that routes a cell on a separated paths by traffic pattern and the scheduling algorithm that processes a maximum 2N cell at once in the control part. Besides, when cells is congested at an output port, a cell loss probability increases. Thus we use the Output Memory (OM) to reduce the cell loss probability. And we make use of the method that stores the assigned memory (UM, MM) with a cell by a traffic pattern and clears the cell of the Output memory after a fixed saving time to improve the memory utilization rate. The performance of the proposed switch is executed and compared with the conventional policy under the burst traffic condition through both the analysis based on Markov chain and simulation.

• Proceedings of the CALSEC Conference
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• 1999.11a
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• pp.529-534
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• 1999

전자상거래는 구매자와 판매자 모두에게 많은 이점을 제공할 수 있어 최근 이에 관한 연구들이 많이 진행되고 있다. 특히 중소제조업체의 경우, 전자상거래라는 경영환경의 변화는 새로운 기회로 다가오고 있어, 상대적으로 기술력이 취약한 중소제조업체의 전자상거래를 지원하기 위한 요소 기술들의 개발 필요성이 점차 부각되고 있다. 이에 본 연구에서는 중소 금형제조업체의 판매과정을 사이버 공간에서 수행할 수 있는 전자상거래 기술을 개발하였다. 일반적으로 변화하는 경영환경에서는 생산과 관련된 계획과 통제가 보다 더 신속하고 정확하게 이루어져야 한다. 즉 전자상거래 환경에서의 제조업체는 구매자가 요구한 제품의 생산과 납기일을 맞추어 줄 수 있는지의 여부를 실시간으로 응답할 수 있어야 한다. 나아가서 인터넷을 통해 접수된 주문들은 해당 제조업체의 생산능력을 초과할 수 있는데 이 때에는 접수된 주문들 중에서 자사의 이익을 극대화할 수 있는 주문집합을 선별하여 접수여부를 결정해야 한다. 이와 같이 전자상거래 환경하에서의 제조업체는 생산과 관련된 정보를 신속하게 전달 받아 주문접수여부에 관한 의사결정을 올바르게 수행하는 것이 중요한데 본 연구에서는 중소 금형제조업체의 일정계획 및 주문처리를 위한 일정계획 기반의 선정 에이전트의 구조와 방법론을 제시하였다. 지금까지 일정계획에 관한 연구들은 대부분 납기일의 만족과 비용의 최소화 측면을 위주로 다루었다. 그러나 본 연구에서의 문제는 비용의 최소화보다는 납기일을 준수하면서 가장 많은 이익을 가져다 줄 수 있는 최적주문집합을 선정하는 문제를 다루고있다.자료를 수집하고, 통계분석 패키지를 이용하여 자료를 분석하였다. 방식을 결합한 하이브리드 형태이다.인터넷으로 주문처리하고, 신속 안전한 배달을 기대한다. 더불어 고객은 현재 자신의 물건이 배달되는 경로를 알고싶어 한다. 웹을 통해 물건을 주문한 고객이 자신이 물건의 배달 상황을 웹에서 모니터링 한다면 기업은 고객으로 공간적인 제약으로 인한 불신을 불식시키는 신뢰감을 주게 된다. 이러한 고객서비스 향상과 물류비용 절감은 사이버 쇼핑몰이 전국 어디서나 우리의 안방에서 자연스럽게 점할 수 있는 상황을 만들 것이다.SP가 도입되어, 설계업무를 지원하기위한 기본적인 시스템 구조를 구상하게 된다. 이와 함께 IT Model을 구성하게 되는데, 객체지향적 접근 방법으로 Model을 생성하고 UML(Unified Modeling Language)을 Tool로 사용한다. 단계 4)는 Software Engineering 관점으로 접근한다. 이는 최종산물이라고 볼 수 있는 설계업무 지원 시스템을 Design하는 과정으로, 시스템에 사용될 데이터를 Design하는 과정과, 데이터를 기반으로 한 기능을 Design하는 과정으로 나눈다. 이를 통해 생성된 Model에 따라 최종적으로 Coding을 통하여 실제 시스템을 구축하게 된다.the making. program and policy decision making, The objectives of the study are to develop the methodology of modeling the socioeconomic evaluation, and b

• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.793-805
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• 2001

In the recent priority system, high-priority packet will be served first and low-priority packet will be served when there isn\`t any high-priority packet in the system. By the way, even high-priority packet can be blocked by HOL (Head of Line) contention in the input queueing System. Therefore, the whole switching performance can be improved by serving low-priority packet even though high-priority packet is blocked. In this paper, we study the performance of preemptive priority in an input queueing switch for high speed switch system. The analysis of this switching system is taken into account of the influence of priority scheduling and the window scheme for head-of-line contention. We derive queue length distribution, delay and maximum throughput for the switching system based on these control schemes. Because of the service dependencies between inputs, an exact analysis of this switching system is intractable. Consequently, we provide an approximate analysis based on some independence assumption and the flow conservation rule. We use an equivalent queueing system to estimate the service capability seen by each input. In case of the preemptive priority policy without considering a window scheme, we extend the approximation technique used by Chen and Guerin [1] to obtain more accurate results. Moreover, we also propose newly a window scheme that is appropriate for the preemptive priority switching system in view of implementation and operation. It can improve the total system throughput and delay performance of low priority packets. We also analyze this window scheme using an equivalent queueing system and compare the performance results with that without the window scheme. Numerical results are compared with simulations.

• The Korean Journal of Air & Space Law and Policy
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• v.27 no.1
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• pp.29-73
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• 2012

Aviation safety is the State and industry's top priority and more scientific approaches for fatigue management should be needed. There are lately various studies and regulation changes for crew fatigue management with ICAO, FAA and EASA. ICAO issued the provisions of fatigue management for flight crew since 1st edition, 1969, of Annex 6 operation of aircraft as a Standards and Recommended practice(SARPs). Unfortunately, there have been few changes and improvement to fatigue management provisions since the time they were first introduced. However the SARPs have been big changed lately. ICAO published guidance materials for development of prescriptive fatigue regulations through amendment 33A of Annex 6 Part 1 as applicable November 19th 2009. And then ICAO introduced additional amendment for using Fatigue Risk Management System (FRMS) with $35^{th}$ amendment in 2011. According to the Annex 6, the State of the operator shall establish a) regulations for flight time, flight duty period, duty period and rest period limitations and b) FRMS regulations. The Operator shall implement one of following 3 provisions a) flight time, flight duty period, duty period and rest period limitations within the prescriptive fatigue management regulations established by the State of the Operator; or b) a FRMS; or c) a combination of a) and b). U.S. FAA recently published several kinds of Advisory Circular about flightcrew fatigue. U.S. passed "Airline Safety and FAA Extension Act of 2010" into law on August 1st, 2010. This mandates all commercial air carriers to develop a FAA-acceptable Fatigue Risk Management Plan(FRMP) by October 31st, 2010. Also, on May 16, 2012, the FAA published a final rule(correction) entitled 'Flightcrew Member Duty and Rest Requirements; correction to amend its existing prescriptive regulations. The new requirements are required to implement same regulations for domestic, flag and supplemental operations from January 4, 2014. EASA introduced a Notice of Proposed Amendment (NPA) 2010-14 entitled "Draft opinion of the European Aviation Safety Agency for a Commission Regulation establishing the implementing rules on Flight and Duty Time Limitations and Rest Requirements for Commercial Air Transport with aeroplanes" on December 10, 2010. The purpose of this NPA is to develop and implement fatigue management for commercial air transport operations. Comparing with Korean and foreign regulations regarding fatigue management, the provisions of ICAO, FAA, EASA are more considering various fatigue factors and conditions. Korea regulations should be needed for some development of insufficiency points. In this thesis, I present the results of the comparative study between domestic and foreign regulations in respect of fatigue management crew member. Also, I suggest legal proposals for amendment of Korea Aviation act and Enforcement Regulations concerning fatigue management for crew members. I hope that this paper is helpful to change korea fatigue regulations, to enhance aviation safety, and to reduce the number of accidents relating to fatigue. Fatigue should be managed at all level such as regulators, experts, operators and pilots. Authority should change surveillance mind-set from regulatory auditor to expert adviser. Operators should identify various fatigue factors and consider to crew scheduling them. Crews should strongly manage both individual and duty-oriented fatigue issues.