• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10B
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• pp.876-890
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• 2003

This paper proposes a protocol for the reliableand QoS-aware multicast transport, which is called the Enhanced Communications Transport Protocol (ECTP). The ECTP has so far been developed and standardized in ITU-T SG17 and ISO/IEC JTC 1/SC 6. Differently from the conventional reliable multicast, as shownin the IETF RMT WG, the ECTP additionally provides several distinct features such as tight control of multicast session, tree-based error control, and QoS management. For the tight control of multicast connections, the sender is at the heart of one-to-many group communications, and it is responsible for overall connection management such as connection creation/termination, pause/resumption, and the join and leave operations. for tree-based reliability control, ECTP configures a hierarchical tree during connection creation. Error control is performed within each local group defined by a control tree, which was partly designed like the IETF TRACK approach. Each parent retransmits lost data in response to retransmission requests from its children. For QoS management, ECTP supports QoS negotiation for resource reservation, and it also provides QoS monitoring and maintenance operations. ECTP has been implemented and tested on Linux machine, along with Application Programming Interfaces based on Berkeley sockets. For basic testing of the ECTP functionality, we give some preliminary experimental results for performance comparison of ECTP and TCP unicast transports. In conclusion, we describe the status of ECTP experimentations over APAN/KOREN testbed networks

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.4
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• pp.134-144
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• 2014

With the advent of lean-six sigma era, an extensive use of analytic tools such as control charts is required in the field of manufacturing. In relation to statistical quality control (SQC) or process control (SPC), the Korean standards have undergone a meaningful change. In this study, the theoretic backgrounds for evaluating the control limits in connection with the variable control charts are examined in view of better understanding the related constants and coefficients. This paper is intended to help the quality control practitioners understand the mathematical backgrounds by comparing related quality control constants and also to encourage them to make use of and to take the advantage of the variable control charts which are very useful for implementing the concept of lean-six sigma in many industrial sites.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.12
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• pp.1529-1538
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• 1999

광대역 액세스 망은 B-ISDN 환경에서 다양한 유형의 가입자들을 서비스 노드로 집선하는 기능을 수행한다. ITU-T의 SG13에서는 광대역 액세스 망과 서비스 노드 사이에서 ATM 자원의 동적인 할당 및 해제를 위하여 연결 제어 프로토콜의 표준화를 수행하고 있다. ATM 연결의 설정을 위한 연결 제어 프로토콜과 신호 프로토콜의 연동 기능은 서비스 노드에서 수행되며, ITU-T에서는 순차적 연동 모델을 채택하고 있다. 순차적 연동 모델은 SN에서 각 프로토콜의 절차가 순차적 방식으로 연동되므로 연결 지연이 크다. 본 논문에서는 광대역 액세스 망의 도입으로 인한 연결 설정 지연을 최소화하기 위하여 병렬형으로 수행되는 연동 모델을 제시하였다. 그리고 본 논문에서 제안한 병렬형 연동 모델의 성능 분석을 통하여 순차적 연동 모델과의 연결 설정 지연 및 완료비에 대한 비교, 분석을 수행하였다. 성능 분석에서 사용된 워크로드 파라미터는 RACE MAGIC 프로젝트의 결과를 적용하였다. Abstract In B-ISDN environment, various subscribers are concentrated into a service node via a broadband access network. The SG13 of ITU-T is standardizing a connection control protocol which provides dynamic allocation of ATM resources between an access network and a service node. To establish an ATM connection, interworking functions between the connection control protocol and the signaling protocol are performed at the service node. ITU-T adopts the sequential interworking model. In this paper, we propose the parallel interworking model which minimizes the overall connection setup delay by introducing the access network. Using the performance analysis, we compare our proposed parallel model with the existing sequential model in terms of connection setup delay and completion ratio. The workload parameters of RACE MAGIC project are applied to the analysis and simulation.

• Journal of Magnetics
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• v.20 no.2
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• pp.166-175
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• 2015

In this study, we describe the design method of a Brush-less DC (BLDC) motor with delta winding connection. After designing delta winding connection model with the $60^{\circ}$ flat-top region of the Back Electro-Motive Force (BEMF), an ideal current source analysis and a voltage source analysis, with a 6-step control, were conducted primarily employing Finite Element Method. In addition, as a current controller, we considered the Current Regulator with PI controller using Simulink for the comparison of torque characteristics. When the input current is controlled, the switching regions and reference signals are determined by means of the phase BEMF zero-crossing point. In reality, the input current variation depends on the inductance as well as input voltage, and it causes a torque ripple after all. Therefore, each control method considered in this research showed different torque ripple results. Based on the comparison, the causes of the torque ripple have been verified in detail.

• The Transactions of the Korea Information Processing Society
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• v.4 no.7
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• pp.1788-1796
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• 1997

In this paper, we propose a new connection admission control(CAC) algorithm for traffic control in ATM network in which traffic estimation is performed based on user-specified parameters at every moment of connection request or connection release by recursive formula which makes real-time calculation possible. And traffic estimation using cell flow measurement is carried out when the number of connectioned calls does not change during a measurement reflection period. Performance analysis of the proposed method is carried out using several aspects for homogeneous and heterogeneous bursty traffic. The results showed that the proposed CAC method revealed better performance, than conventional CAC method for burst model in both utilization and QoS point of view.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.81-88
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• 2017

This study deals with the optimal design of a hybrid control system composed of a combination of active control system and passive control system for effective seismic performance improvement of two adjacent structures. The proposed hybrid control system adopts a configuration of installing an active control device in one building and connecting two adjacent structures with a passive control device so that the one-side active control force can be bi-directionally applied to both buildings through the passive connecting devices. In order to derive the optimal performance of the proposed system, the design parameters of the passive and active control systems were searched using the genetic algorithm. Numerical simulations of 10-story and 8-story buildings have been performed to verify the effectiveness of the proposed technique. For the purpose of comparison, the conventional independent control system with two identical active control systems being installed separately for each structure was also optimally designed and its seismic response has been evaluated as well. From the comparative results of the two control systems, it is demonstrated that the proposed hybrid control system requires larger control force for its one-side active control device than the conventional independent control system does for each of both-side active devices, but quite less than the total control force required for both-side devices of the independent control system, while maintaining similar seismic performance. Therefore, the proposed system is more economical and reliable than the conventional independent control system with two identical active devices.

• The KIPS Transactions:PartC
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• v.13C no.7 s.110
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• pp.923-932
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• 2006

For the successful promotion about the NGN (Next Generation Network), centralized network control and management technology is required to guarantee QoS and Traffic Engineering. This paper describes SNMP. Web Services and Network Open Interface based connection management scheme which can be used in centralized server based network in which the control plane is separated from transport plane. We also constructed platforms about each of these connection management schemes and performed comparing and analyzing the performance of connection setup delays.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.8
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• pp.731-737
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• 2012

In this paper the usage of Bluetooth in networked control systems is described. ACL links and commonly used serial port profile built on top of ACL links are analyzed and their problems such as unpredictable latency are discovered. SCO link packet scheduling, latency estimation and setup procedure are examined. SCO link is suggested as proper link for NCS, due to its low latency and low variance. Smith predictor use for latency compensation is described and its impact on control performance is estimated. A number of experiments on DC motor position control are performed and control performance of system utilizing SCO link with and without Smith predictor is proved to be higher than control performance of system utilizing ACL link.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2101-2105
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• 2003

Recently the number of Internet users has very sharply increased, and the number of intrusions has also increased very much. Consequently, security products are being developed and adapted to prevent systems and networks from being hacked and intruded. Even if security products are adapted, however, hackers can still attack a system and get a special authorization because the security products cannot prevent a system and network from every instance of hacking and intrusion. Therefore, the researchers have focused on an active hacking prevention method, and they have tried to develop a traceback system that can find the real location of an attacker. At present, however, because of the characteristics of Internet - diversity, anonymity - the real-time traceback is very difficult. To over-come this problem the Network-based Real-Time Connection Traceback System (NRCTS) was proposed. But there is a security problem that the victim system can be hacked during the traceback. So, in this paper, we propose modified NRCTS with connection redirection technique. We call this traceback system as Connection Redirected Network-based Real-Time Connection Traceback System (CR-NRCTS).

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.9-17
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• 2020

In this paper, as part of the research for the infrastructure of very high flexible and reconfigurable data center using very high speed crossbar switches, we developed a simulator that can model two and three dimensional connection structure of switches with an efficient control algorithm using software defined network and verified the functions and analyzed the performance accordingly. The simulator consists of a control module and a switch module that was coded using Python language based on the Mininet and Ryu Openflow frameworks. The control module dynamically controls the operation of switching cells using a shortest multipath algorithm to calculate efficient paths adaptively between configurable computing resources. Performance analysis by using the simulator shows that the three-dimensional switch architecture can accommodate more hosts per port and has about 1.5 times more successful 1:n connections per port with the same number of switches than the two-dimensional architecture. Also simulation results show that connection length in a 3-dimensional way is shorter than that of 2-dimensional way and the unused switch ratio in a 3-dimensional case is lower than that of 2-dimensional cases.