• Proceedings of the KSR Conference
• /
• 2003.10b
• /
• pp.326-333
• /
• 2003

Railway system is consisted of resources such as rail-line, signalling system, and railcars. It is necessary to efficiently utilize these limited and expensive resources as much as possible up to given line capacity. So far, we treat the line capacity as the criteria for evaluating investment alternatives or for restricting train frequencies, and this criteria is calculated statical and experimental numerical formula. But, line capacity has special attribute that changes dynamically according to operational conditions, so there is a need of new line capacity estimation system. In this paper, we present systematic line capacity analysis model. The proposed model has three main components; TPS(tain performance simulator), PES(parameter evaluation simulator), LCS(line capacity simulator).

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.5
• /
• pp.193-200
• /
• 2003

A computer simulation program to evaluate the performance of railway systems and train operation plans and the effects of new technologies is provided. The program has the functions of tracing the movements of trains on railway network following the indication of railway signalling system and obeying all kinds of operation rules. An object-oriented technique is applied to model railway system effectively, and it is expected that the program code can be reused easily for other railway simulation programs. Dedicated graphic user interface displaying the simulation outputs by animation during simulation process makes the program convenient to use. Simulation results on the train operations on Kyung-bu line show the proposed program is promising.

• 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.

• Journal of the Korean Society for Railway
• /
• v.19 no.2
• /
• pp.170-186
• /
• 2016

This paper introduces a multi-phase fuzzy risk graph model, representing a method for determining for SIL values for railway industry systems. The purpose of this paper is to compensate for the shortcomings of qualitative determination, which are associated with input value ambiguity and the subjectivity problem of expert judgement. The multi-phase fuzzy risk graph model has two phases. The first involves the determination of the conventional risk graph input values of the consequence, exposure, avoidance and demand rates using fuzzy theory. For the first step of fuzzification this paper proposes detailed input parameters. The fuzzy inference and the defuzzification results from the first step will be utilized as input parameters for the second step of the fuzzy model. The second step is to determine the safety integrity level and tolerable hazard rate corresponding to be identified hazard in the railway industry. To validate the results of the proposed the multi-phase fuzzy risk graph, it is compared with the results of a safety analysis of a level crossing system in the CENELEC SC 9XA WG A0 report. This model will be adapted for determining safety requirements at the early concept design stages in the railway business.

• 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 Korean Journal of Financial Management
• /
• v.24 no.1
• /
• pp.1-27
• /
• 2007

In this study, we investigated the market long-term performance of stock splits by using the Korean Stock Market data from 1998 through 2002. We measured the performance by the event-time portfolio approach with the buy-and-hold abnormal return(BHAR) and the cumulative average abnormal return(CAAR). Also, the calendar-time portfolio approach with one-factor and three factor model were used for avoiding the misspecification model problem. The first of main results in this study was that the stock splits had significantly positive abnormal returns around the month of the stock splits announcements. However, the period BHAR and CAAR after the announcement month were significantly negative. This negative long-term abnormal returns were confirmed by the calendar-time portfolio approach. The results suggested that the abnormal return followed by the stock splits seemed to be positive in the short-term period. Second, there was no the difference of the long term performance between the high and the low split ratios. The operating income performance in the periods followed by the stock splits announcements grew worse. Therefore, the signalling effects, the managers of the firm under considering the stock splits would make use of splits as a form of signals for the upward changes in the cash flow or profits, could not be found. Finally, in contrast to Fama, Fisher, Jensen and Roll(1969), the significant negative abnormal returns following the stock splits were still found irrespective of the change of dividend payout ratio.

• Journal of Industrial Technology
• /
• v.25 no.B
• /
• pp.221-229
• /
• 2005

We present a numerical analysis of the optimal group number for minimizing the average paging delay. In the analysis, we consider uniform distributions for location probability conditions and apply M/D/1 queueing model to paging message queues of cells. We also get the lower bounds of group numbers and investigate the minimum transmission capacity under average paging delay constraints. Minimizing the average paging delay is important because it means minimizing the amount of bandwidth used for locating mobile terminals. Therefore, the numerical results of this paper will be very useful in PCS system when designing its signalling capacity due to its simplicity and effectiveness.

• Nutritional Sciences
• /
• v.5 no.4
• /
• pp.228-233
• /
• 2002

The low molecular weight zinc-binding protein metallothionein(MT) contains 32% cysteine and has been shown to efficiently scavenge hydroxyl radicals in vitro. MT expression is induced by oxidative stress and an antioxidant role for this protein has therefore been proposed. This review mainly focuses on the evidence for this role arising from studies using genetically modified animals and cells which either over- or under-express MT. Despite some considerable disparity of results in the literature, reported studies do generally support an antioxidant role. Nevertheless, oxidant stress at non-physiological treatment levels has been the preferred experimental model and there is little information about the role of MT in physiological oxidative stress. Although it is presumed that the mechanism by which MT has an antioxidant effect involves oxidation of cysteinal thiols, it is possible that zinc release from MT is in itself an important signalling factor.

• Journal of the Korean Society for Railway
• /
• v.7 no.2
• /
• pp.114-119
• /
• 2004

According to the computerization of railway signalling systems. the communication protocol for interface between these systems are required. Therefore the new communication protocol for railway signaling system is required. Generally, there are two verification method for new designed protocol in the industrial and academic fields. One is the laboratory testing method which is very popular and general technique. In our research the comparison between existing and new designed protocol for signaling is described and the verification test results are also represented. From these laboratory test, we are verified the conformance of new designed protocol. Another method is verified by formal method. The format verification method is widely used at safety-critical system design but this approach is nor popular at verification communication protocol. However it is very important to verify the safety of new designed protocol for railway signaling system because signaling systems are very safety-critical systems. So, the methodology for formal verification of designed protocol is also reviews in this paper.

• Proceedings of the Korean Nutrition Society Conference
• /
• 2002.11b
• /
• pp.1171-1177
• /
• 2002

The low molecular weight zinc-binding protein metallothionein (MT) contains 32% cysteine and has been shown to efficiently scavenge hydroxyl radicals in vitro. MT expression is induced by oxidative stress and an antioxidant role for this protein has therefore been proposed. This review mainly focuses on the evidence for this role arising from studies using genetically modified animals and cells which either over-or under-express MT. Despite some considerable disparity of results in the literature, reported studies do generally support an antioxidant role. Nevertheless, oxidant stress at non-physiological treatment levels has been the preferred experimental model and there is little information about the role of MT in physiological oxidative stress Although it is presumed that the mechanism by which MT has an antioxidant effect involves oxidation of cysteinal thiols, it is possible that zinc release from MT is in itself an important signalling factor.