• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.14 no.3
• /
• pp.200-208
• /
• 2014

This paper presents the control of an inverted pendulum system using intelligent algorithms, such as fuzzy logic and neural networks, for advanced control education. The swing up balancing control of the inverted pendulum system was performed using fuzzy logic. Because the switching time from swing to standing motion is important for successful balancing, the fuzzy control method was employed to regulate the energy associated with the angular velocity required for the pendulum to be in an upright position. When the inverted pendulum arrived within a range of angles found experimentally, the control was switched from fuzzy to proportional-integral-derivative control to balance the inverted pendulum. When the pendulum was balancing, a joystick was used to command the desired position for the pendulum to follow. Experimental results demonstrated the performance of the two intelligent control methods.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.9A
• /
• pp.1542-1552
• /
• 2001

MPLS 망에서 설정된 LSP (Label Switched Path)내에 링크/노드 장애나 혼잡이 발생한 트래픽을 대체 경로로 우회시킴으로써 신뢰성 있는 서비스를 제공하는 것은 필수적이다. 기존에 제안된 기법들은 장애가 발생하기 전에 대체 경로를 미리 설정하기 때문에 빠른 장애 복구를 제공할 수 있지만 자원 낭비가 심하며 기본 LSP와 대체 LSP가 모두 장애인 경우에는 대처할 수가 없는 문제점을 가지고 있다. 본 논문에서는 장애를 탐지한 노드가 기본 경로상에 존재할 수 있는 가능한 모든 대체 경로 중에서 비용이 최소인 대체 경로를 계산한 후에 그 경로를 따라서 대체 LSP를 설정하는 동적 복구 기법을 제안한다. 제안된 기법은 최소 비용인 대체 경로를 계산하기 위하여 제안된 알고리즘을 사용함으로써 비교적 빠른 시간 내에 대체 LSP를 설정할 수 있으며, 자원 효율성이 높고, 기본경로와 대체 경로가 장애인 경우에도 대처할 수 있다. 제안된 기법의 성능을 평가하기 위하여 링크 장애, 노드 장애, 대체 경로 장애, 그리고 동시 발생 장애에 대하여 각각 시뮬레이션 하였다. 실험 결과, 제안된 기법은 기존의 기법들과 비교해서 동시 발생 장애에서는 성능이 좋지 않았지만, 링크 장애와 노드 장애의 경우에 비교적 성능이 좋았고, 기본 경로와 대체 경로가 장애인 경우에도 복구할 수 있었으며 자원 효율성에서는 월등히 우수했다.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.24 no.62
• /
• pp.11-20
• /
• 2001

At the initial deployment of B-ISDN, the heterogeneity of services and the bandwidth requirement make dimensioning of B-ISDN much more complicated than the dimensioning of homogeneous circuit or packet switched networks. Therefore B-ISDN must be extended gradually according to future telecommunication technology or service demands. In this paper, we propose a mathematical formulation for dimensioning problem of B-ISDN extension, considering the characteristics of ATM(Asynchronous Transfer Mode) such as various quality of services, the statistical multiplexing effects of VPCs(Virtual Path Connections) and the modularity of transmission links allocated when new B-ISDN nodes are given. The algorithm based on the simultaneous linear approximation technique and Lagrangian relaxation method and some numerical results are also presented.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.10
• /
• pp.2740-2751
• /
• 1999

Critical to more widespread use of Internet telephony are the smooth interoperability with the existing telephone network and the improved quality of voice connections. Of these requirements, this interoperability comes through the use of Internet Telephony Gateway's which perform protocol translation between an IP network and the Public Switched Telephone Network. In this paper, we have focused on the necessity and possibility of interoperability, and furthermore derives the necessary requirements for interoperability between IP networks and PSTN. For this purpose, we have analyzed the signaling protocols for gateway system. Then, we have modelled the inter-working part using the Petri-Net model. Through reachability trees of the Petri-Net model, we have confirmed that interoperability is possible, and that characteristics of deadlock, liveness, and boundness are satisfied.

• Korea Multimedia Society
• /
• v.1 no.1
• /
• pp.19-32
• /
• 1997

There are many kinds of predominant modes to transfer Multimedia information on internet in the world. Various methods are applied to get real time multimedia data as possible as we need. At the moment it is very difficult to use acceptable technologies for performe those methods effectively on the Networks. This paper gives the alternative directions and trends for research and development of multimedia transmission on the internet. ATM is one of the best mode to transfer mass-multimedia data at the high speed on the Broad-Band ISDN until now. And xDSL (xDigital Subscriber Line) is an excellent typical method on the PSTN (Public Switched Telephone Network) using old type telephone line. But they are not yet applied into the phase of practical use together this time. So this paper analyzes what we need and how to develop the multimedia transmission modes which we can send on the internet without a problem or any difficulty for our various multimedia information all the time under low cost and high speed.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.44 no.10
• /
• pp.29-36
• /
• 2007

IP paging strategy, one of the solutions for derived problems in IP mobility support protocol, reduces the messages and the overheads over the network, since there is not registration procedure when a mobile terminal moves into a new router within the same paging area. However, the fact that the mobile terminals with the previous strategy consume electrical power continuously for paging signal reception obstructs the application of IP paging strategy to the IP-based wireless sensor networks. In this paper, we propose a discontinuous paging reception strategy based on the characteristics of the wireless sensor networks and their mobile terminals. As a result of the mathematical analysis, the proposed strategy significantly reduces the terminals' power consumption. In addition, by setting the relating parameters as appropriate values, the proposed strategy can be switched to the continuous reception strategy, or can be adjusted to limit the terminals' power consumption or paging delay.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.5
• /
• pp.2313-2318
• /
• 2012

With the widely applications of tactical radio networks, end-to-end secure speech communication in the heterogeneous network has become a very significant security issue. High-grade end-to-end speech security can be achieved using encryption algorithms at user ends. However, the use of encryption techniques results in a problem that encrypted speech data cannot be directly transmitted over heterogeneous tactical networks. That is, the decryption and re-encryption process must be fulfilled at the gateway between two different networks. In this paper, in order to solve this problem and to achieve optimal end-to-end speech security for heterogeneous tactical environments, we propose a novel mechanism for end-to-end secure speech transmission over ultra high frequency (UHF) and public switched telephone network (PSTN) and evaluate against the performance of conventional mechanism. Our proposed mechanism has advantages of no decryption and re-encryption at the gateway, no processing delay at the gateway, and good inter-operability over UHF and PSTN.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.4B
• /
• pp.162-169
• /
• 2005

Network traffic measurements show that the data traffic on packet switched networks has the self-similar features which is different from the traditional traffic models such as Poisson distribution or Markovian process model. Most of the call admission control researches have been done on the performance analysis of a single network switch. It is necessary to consider the performance analysis of the proposed admission control scheme under interconnected switch environment because the data traffic transmits through switches in networks. From the simulation results, it is shown that the call admission control scheme may not operate properly on the interconnected switch even though the scheme works well on a single switch. In this parer, we analyze the cell loss probability, utilization and self-similarity of output ports of the interconnected networks switch by using shared buffer memory management schemes and propose the new call admission control scheme considering the interconnected network switches under self-similar traffic environments.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.3
• /
• pp.729-741
• /
• 1999

ATM networks are widely deployed as the network that is capable of supporting multimedia services efficiently now. To date, a large portion of ATM connections, particularly in the WAN environment, have been of a permanent virtual circuits-requiring management intervention for set-up and tear-down. However, switched virtual circuits are required to support a range of desired characteristics on demand, to a reachable end user. To establish, maintain and release on-demand call/connections, the user-network interface(UNI) and node-node interface(NNI) signalling capabilities are required. Two protocols have been specified for NNI signalling within a public network: the broadband integrated-services user part(B-ISUP) protocol specified by the ITU-T, and the private network-network interface(PNNI) protocol specified by the ATM Forum. PNNI offers different type of internetwork or internodal interface from the traditional B-ISUP approach favored to date public network operators. In spite of its name, PNNI may find its place in network service provide networks as well as in private networks. Thus many public network operators and ATM equipment manufacturers are still unable to choose the NNI interface architecture of their system. In this paper, we survey the characteristics of the B-ISUP and PNNI protocols, and investigate the applicability issue of these specifications to the ATM-based Information Infra-Network of Korea. Analyzing the characteristics of the two protocols and clarifying the NNi requirements of the ATM-based Information Infra-Network of Korea, we propose that the B-ISUP protocol is more suitable than PNNI.

• The KIPS Transactions:PartC
• /
• v.9C no.6
• /
• pp.893-902
• /
• 2002

MPLS enables efficient explicit routing, and thus provides great advantages in supporting traffic engineering. Exploiting this capability, we Propose a load balancing scheme which deploys a multipath routing. It is named LBM (Load Balancing in MPLS networks), and targets at efficient network utilization as well as performance enhancement. LBM establishes multiple LSP (Label Switched Path)s between a pair of ingress-egress routers, and distributes traffic over these LSPs at the new level. Its routing decision is based on both the length and the utilization of the paths. In order to enhance the efficiency of a link usage, a link is limited to be used by shorter paths as its utilization becomes higher Longer paths are considered to be candidate alternative paths as the utilization of shorter paths becomes higher. Simulation experiments are performed in order to compare the performance of LBM to that of static shortest path only scheme as well as the other representative dynamic multipath traffic distribution approaches. The simulation results show that LBM outperforms the compared approaches, and the performance gain is more significant when the traffic distribution among the ingress-egress pairs is non-uniform.