• Title/Summary/Keyword: average arrival ratio

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Congestion Analysis in the Inner Harbour of Ulsan Using a Scenario (시나리오를 이용한 울산 내항의 혼잡 분석)

  • Ha, Chang-Seung;Baek, Ih-Huhm
    • Journal of Fisheries and Marine Sciences Education
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    • v.19 no.2
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    • pp.278-287
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    • 2007
  • Since traffic congestion ratio at any given port fluctuates on the number of arriving and departing vessels, the total tonnage of freight volume being handled, and the number of berth in operation and other factors, there exists a need to numerically analyze the waterway traffic volume. However, there are no effective regulations in regards to the waterway traffic analysis prior to expansion of a port facility. The current analysis requires the traffic analysis in relation only to the width of the waterway, which clearly falls short of achieving a comprehensive evaluation study that could be used in consideration of port expansion.This study provides five scenarios to execute a comprehensive evaluation study and base for the sensitivity study by analyzing the scenarios. As a result of the sensitivity analysis, the A, B, and C scenarios varies the average arrival ratio of the berth shows 1.1, 1.19, and 1.28 times of delays respectively. Also, The D and E scenarios take place malfunctions of pier shows 1.21 and 1.53 times of delays respectively. Therefore, various strategies of harbor development and method of harbor management are needed for the flexible correspondence to the environmental changes such as the excessive increasing of the freight volume and often taking place of malfunctioning.

A Proposal on Data Priority Based Transaction Scheduling Algorithm and the Comparative Performance Evaluation in Real Time Database Management System (데이타 우선순의에 기초한 트랜잭션 스체줄링 알고리즘의 제안 및 실시간 DBMS에서의 성능 비교연구)

  • Yun, Seok-Hwan;Lee, Jae-Yeong;Park, Chi-Hang
    • The Transactions of the Korea Information Processing Society
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    • v.3 no.4
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    • pp.803-816
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    • 1996
  • It is possible to prevent deadlock if the priority which is conventionally given to transactions is endowed to data items and the transactions with the highest priority among transactions accessing the data item is allowed to proceed. Based on this observation, we proposed a Data-Priority Based Locking Protocol(DPLP) and evaluated its performance against known locking protocols in Real Time Database Management System(RTDBMS). Transaction inter-arrival time(IAT) was varied to determine success ratio, average-lateness, confict ratio and restart ratio, In these simulations we verified that the proposed DPLP performs better than the other protocols.

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Performance Analysis of ATM Switch Using Dynamic Priority Control Mechanisms (동적 우선순위 제어방식을 사용한 ATM 스위치의 성능분석)

  • 박원기
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.4
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    • pp.855-869
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    • 1997
  • In this paper, we proposed two kids of dynamic priority control mechanisms controlling the cell service ratio in order to improve the QOS(Quality of Service). We also analyse theoretically the characteristics of cell loss probability and mean cell delay time by applying the proposed priority control mechanisms to ATM switch with output buffer. The proposed priority control mechanisms have the same principles of storing cells into buffer but the different principles of serving cells from buffer. The one is the control mechanism controlling the cell service ratio according to the relative cell occupancy ratio of buffer, the other is the control mechanism controlling the cell service ratio according to both the relative cell occupancy ratio of buffer and the average arrival rate. The two service classes of our concern are the delay sensitive class and the loss sensitive class. The analytical results show that the proposed control mechanisms are able to improve the QOS, the characteristics of cell loss probability and mean cell delay time, by selecting properly the relative cell occupancy ratio of buffer and the average arrival rate. conventional DLB algorithm does not support synchronous cells, but the proposed algorithm gives higher priority to synchronous cells. To reduce synchronous cell loss rate, the synchronous cell detector is used in the proposed algorithm. Synchronous cell detector detects synchronous cells, and passes them cells to the 2nd Leaky-Bucket. So it is similar to give higher priority to synchronous cells. In this paper, the proposed algorithm used audio/video traffic modeled by On/Off and Two-state MMPP, and simulated by SLAM II package. As simulation results, the proposed algorithm gets lower synchronous cell loss rate than the conventional DLB algorithms. The improved DLB algorithm for multimedia synchronization can be extended to any other cells which require higher priority.

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Performance Comparison of CDMA and TDMA protocols in radio access system for Integrated Voice/Data Services (음성 및 데이터서비스를 위한 무선접속시스템에서 CDMA와 TDMA방식의 성능비교)

  • 고종하;양영님;이정규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6A
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    • pp.820-831
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    • 1999
  • In this paper, we have compared the performance of a D-TDMA protocol with that of a CDMA protocol, in radio access system for integrated voice/data services.The D-TDMA protocol is based on a generic dynamic channel assignment approach to be followed a combination of “circuit mode” reservation for voice calls, along with dynamic first-come-first served assignment of remaining capacity for data messages. In the CDMA protocol, we have used the voice activity detection to reduce the interface power of other mobiles in internal and external cells, and analyzed the interference power ratio. Also we have computed BER(Bit Error Rate) by using this interference power ratio and evaluated voice blocking probability(voice packet loss probability) and data transmission delay, according to average data length and average data arrival rate.We have found the CDMA protocol achieves comparatively higher performance for short data length, regardless of data arrival rate. Otherwise, the data transmission delay of D-TDMA protocol is shorter than that of the CDMA protocol for long data message.

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The enhance driority transfer control mechanism for multimedia communication in ATM networks (ATM 망에서 멀티미디어 통신을 위한 EPT(enhanced priority transfer)제어기법)

  • 박성호;박성곤;최승권;조용환
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.23 no.9A
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    • pp.2249-2257
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    • 1998
  • In this paper, we propose the enhanced priority control algorithm that adaptively controls the cell service ratio according to the relative cell occupancy ratio of buffer. The asynchronous transfer mode (ATM) provides the means to support various multimedia services in broadband networks. To support multimedia services, various data traffics of different priorities should be controlled effectively. And also it needs congestion control functions required in the netowrk to carry out the control operation. To accomplish this in a flexible and effective manner, priority classes for the different services ar ecommonly used. The proposed enhanced priority control mechanism have two service calsses of the delay sensitive class and the loss sensitive class. The simulation results show that te proposed control mechanism improves the QoS, the charateristics of cell loss probability and mean cell delay time, by selecting propeor relativ ecell occupancy ratio of buffer and the average arrival rate.

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Optimal Stochastic Policies in a network coding capable Ad Hoc Networks

  • Oh, Hayoung
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.12
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    • pp.4389-4410
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    • 2014
  • Network coding is a promising technology that increases system throughput by reducing the number of packet transmissions from the source node to the destination node in a saturated traffic scenario. Nevertheless, some packets can suffer from end-to-end delay, because of a queuing delay in an intermediate node waiting for other packets to be encoded with exclusive or (XOR). In this paper, we analyze the delay according to packet arrival rate and propose two network coding schemes, iXOR (Intelligent XOR) and oXOR (Optimal XOR) with Markov Decision Process (MDP). They reduce the average delay, even under an unsaturated traffic load, through the Holding-${\chi}$ strategy. In particular, we are interested in the unsaturated network scenario. The unsaturated network is more practical because, in a real wireless network, nodes do not always have packets waiting to be sent. Through analysis and extensive simulations, we show that iXOR and oXOR are better than the Distributed Coordination Function (DCF) without XOR (the general forwarding scheme) and XOR with DCF with respect to average delay as well as delivery ratio.

QoS Improvement Analysis Call Admission Control(CAC) Algorithm based on 3GPP PBNM (3GPP 정책기반에서 호 수락 제어(CAC) 알고리즘 적용에 따른 QoS 성능개선)

  • Song, Bok-Sob;Wen, Zheng-Zhu;Kim, Jeong-Ho
    • The Journal of the Korea Contents Association
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    • v.12 no.4
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    • pp.69-75
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    • 2012
  • In this paper, to provide various services of QoS, and moreover applying traffic ratio to CAC(Call Admission Control) algorithm tested how long average data rate and the average packet delay time. When CAC algorithm is not applied, traffic mixture ratio is 1:1:4:4, the FTP Service 0.4, web services 0.6, streaming service 0.7, the packet delay requirements are not satisfied. On the other hand CAC Algorithm is applied, all the service of packet delay are satisfied with arrival rate. Therefore, we can make sure that applying of CAC of traffic control WWW, FTP, Video, VoIP can guarantee the various services of QoS.

An Approach to Calibrating a Progression Adjustment Factorat Signalized Intersections - Toward Theory of Background - (신호등(信號燈) 연동화보정계수(連動化補正係數) 산출(算出) 모형(模型)의 개발(開發) - 이론적(理論的) 고찰(考察)을 중심(中心)으로 -)

  • Lee, Yong Jae;Choi, Woo Hyuck
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.3
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    • pp.379-390
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    • 1994
  • The recent study of the delay models have assumed random arrival which has a constant average flow rate throughout the cycle. However, where signals are spaced closely together or form part of progressive system, platoon flows are common and more closely represent reality. In such cases, those results are quite different pattern of estimated delay from that of observed one. In order to solve this problem, the 1985 HCM takes Progression Adjustment Factor (PAF) into account. In the 1985 HCM, however, it has deficiencies in defining and applying it, such as platoon ratio ($R_p$) and platoon arrival type. The Purpose of this study is to investigate theoretically the predictive ability of the individual models concerned through comparing the estimated delay and PAF suggested by NCHRP Report 339, KHCM or USHCM (1985) with the observed obtained by field survey at a signalized intersection.

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A Study on the Gap between Theoretical and Actual Ship Waiting Ratio of Container Terminals: The Case of a Terminal in Busan New Port (컨테이너 터미널의 이론적 대기율과 실제 대기율 비교에 관한 연구: 부산항 신항 A 터미널을 대상으로)

  • Lee, Jung-Hun;Park, Nam-Kyu
    • Journal of Korea Port Economic Association
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    • v.34 no.2
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    • pp.69-82
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    • 2018
  • The number of ships serviced at the container terminals in Busan is increasing by 2.9% per year. In spite of the increase in calling ships, there are no official records of waiting rate by the port authority. This study attempts to compare the theoretical ship waiting ratio and actual ship waiting ratio. The actual ship waiting ratio of container terminals is acquired from the 2014 to 2016 data of PORT-MIS and Terminal Operating System (TOS). Furthermore, methods and procedures to measure the actual ship's waiting rate of container terminal are proposed for ongoing measurement. In drawing the theoretical ship waiting ratio, the queuing theory is applied after deploying the ship arrival probability distribution and ship service probability distribution by the Chi Square method. As a result, the total number of ships waiting in a terminal for three years was 587, the average monthly service time and the average waiting time was 13.8 hours and 17.1 hours, respectively, and the monthly number of waiting ships was 16.3. Meanwhile, according to the queuing theory with multi servers, the ship waiting ratio is 31.1% on a 70% berth occupancy ratio. The reason behind the huge gap is the congested sailing in the peak days of the week, such as Sunday, Tuesday, and Wednesday. In addition, the number of waiting ships recorded on Sundays was twice as much as the average number of waiting ships.

Software Development for Optimal Productivity and Service Level Management in Ports (항만에서 최적 생산성 및 서비스 수준 관리를 위한 소프트웨어 개발)

  • Park, Sang-Kook
    • Journal of Navigation and Port Research
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    • v.41 no.3
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    • pp.137-148
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    • 2017
  • Port service level is a metric of competitiveness among ports for the operating/managing bodies such as the terminal operation company (TOC), Port Authority, or the government, and is used as an important indicator for shipping companies and freight haulers when selecting a port. Considering the importance of metrics, we developed software to objectively define and manage six important service indicators exclusive to container and bulk terminals including: berth occupancy rate, ship's waiting ratio, berth throughput, number of berths, average number of vessels waiting, and average waiting time. We computed the six service indicators utilizing berth 1 through berth 5 in the container terminals and berth 1 through berth 4 in the bulk terminals. The software model allows easy computation of expected ship's waiting ratio over berth occupancy rate, berth throughput, counts of berth, average number of vessels waiting and average waiting time. Further, the software allows prediction of yearly throughput by utilizing a ship's waiting ratio and other productivity indicators and making calculations based on arrival patterns of ship traffic. As a result, a TOC is able to make strategic decisions on the trade-offs in the optimal operating level of the facility with better predictors of the service factors (ship's waiting ratio) and productivity factors (yearly throughput). Successful implementation of the software would attract more shipping companies and shippers and maximize TOC profits.