• Journal of Korea Multimedia Society
• /
• v.9 no.11
• /
• pp.1503-1514
• /
• 2006

Today, consumers can access Internet from everywhere, therefore most commercial and other organizations provide their services on the Web. As the result, countless Web service systems are already on the Internet and more systems are under construction. Therefore, many researches of verifying that the system to be constructed will not have any deadlock and will run successfully without any problem at the early stage of design have been performed. Several Petri net based verification methods have also been published. However, they have focused on building Petri net models of Web service systems and none of them introduces efficient analysis methods. As a mathematical technique with which we can find the minimum duration time needed to fire all the transitions at least once and coming back to the initial marking in a timed net, the minimum cycle time method has been widely used in computer system analysis. A timed net is a modified version of a Petri net where a transition is associated with a delay time. A delay time used in a timed net is a constant even though the duration time associated with an event in the real world is a stochastic number in general. Therefore, this paper proposes 'Mixedly Distributed Stochastic Timed Net' where a transition can be associated with a stochastic number and introduce a minimum cycle time analysis method for 'Mixedly Distributed Stochastic Timed Net'. We also introduce a method of analysing a Web service system's response time with the minimum cycle time analysis method for 'Mixedly Distributed Stochastic Timed Net.'.

• Korean Journal of Construction Engineering and Management
• /
• v.6 no.4 s.26
• /
• pp.101-112
• /
• 2005

Recently, a curtain wall construction is a exterior finishing components which is most used for shortening time in high-rise building as well as the class of key management factors in cost and schedule control. Also, it is recognized that an effective management for curtain wall process is a major subject to accomplish the project successfully. However, as the current management for curtain wall construction is focused on the construction stage, it makes problems such as errors in business performance, rework by mistakes and duplications, errors and omissions by ineffective information management and there has never been any efficient management from a view of the entire Curtain Wall Life-cycle process. Therefore, the aim of this study is to suggest a stage check point for process improvement in the curtain wall Life-cycle process through current curtain wall process analysis, and then to investigate the cause of waste factors using the Muda method from the Toyota Production System and extract the weighted effects of the waste factors using the analytical hierarchy process method. According to the result, Most of the inefficient factors happened in architectural design stage of the entire curtain wall Life-cycle process and my research identified that detail factors of them are a delay of decision making and an approval in changes, a deficit of engineering capacity and a delay of approval in architectural design drawings by owner, etc.

• Journal of the Korean Society of Safety
• /
• v.25 no.6
• /
• pp.115-122
• /
• 2010

The importance of the life cycle cost (LCC) analysis for bridges has been recognized over the last decade. However, it is difficult to predict LCC precisely since the costs occurring throughout the service life of the bridge depend on various parameters such as design, construction, maintenance, and environmental conditions. This paper presents a methodology for the optimal life cycle cost design of a bridge. Total LCC for the service life is calculated as the sum of initial cost, damage cost, maintenance cost, repair and rehabilitation cost, user cost, and disposal cost. The optimization method is applied to design of a bridge structure with minimal cost, in which the objective function is set to LCC and constraints are formulated on the basis of Korean Bridge Design Code. Initial cost is calculated based on standard costs of the Korea Construction Price Index and damage cost on damage probabilities to consider the uncertainty of load and resistance. Repair and rehabilitation cost is determined using load carrying capacity curves and user cost includes traffic operation costs and time delay costs. The optimal life cycle cost design of a bridge is performed and the effects of parameters are investigated.

• Journal of Korean Society of Transportation
• /
• v.33 no.5
• /
• pp.478-487
• /
• 2015

This study proposed a Variable Speed Limits(VSL) algorithm to use traffic information based on Cumulative Demand-Capacity Analysis and evaluated its performance. According to the analysis result, the total of delay consisted of 3 separate parts. There was no change in total travel time although the total of delay decreased. These effects was analysed theoretically and then, evaluated through VISSIM, a microscopic simulator. VISSIM simulation results show almost same as those of theoretical analysis. Furthermore in SSAM analysis with VISSIM simulation log, the number of high risk collisions decreased 36.0 %. However, the total delay decrease effect is not real meaning of decrease effect because the drivers' desired speed is same whether the VSL model is operated or not. Nevertheless this VSL model maintains free flow speed for longer and increases the cycle of traffic speed fluctuation. In other words, this is decrease of delay occurrence and scale. The decrease of speed gap between upstream and downstream stabilizes the traffic flow and leads decrease number of high risk collision. In conclusion, we can expect increase of safety through total delay minimization according to this VSL model.

• Journal of Preventive Medicine and Public Health
• /
• v.20 no.1 s.21
• /
• pp.1-9
• /
• 1987

Sister chromatid exchanges (SCEs) observed by means of bromodeoxyuridine substitution and fluorescence plus Giemsa (FPG) technique were proposed as a sensitive and quantitative assay for mutagenicity and cytotoxicity in short-term cultures of phytohaemagglutinin (PHA)-stimulated human lymphocytes. Therefore, this study was carried out to investigate the relation between anticancer agents and cytotoxic effects. Chromosomal analysis was performed on metaphase cells that had divided one, two, or three or more times after treatment for SCEs, mitotic indices (MI) and cell cycle kinetics by FPG technique. The results indicate that anticancer agents led to a dose dependent increase in SCE frequency except methotrexate. But, highly inhibited mitotic indices and delayed cell cycle kinetics were observed except for cyclophosphamide. The author suggest that the difference of SCE frequency is due to the differences in the cytotoxic action of anticancer agents, but although the induction of SCEs has a correlation with cell cycle delay, in some cases the induction of SCEs is not always related to cell cycle delay because of different cytotoxic action of anticancer agents.

• Proceedings of the IEEK Conference
• /
• 2003.07a
• /
• pp.414-417
• /
• 2003

In this paper, a performance of Bluetooth piconet is analyzed. Average cycle time, average waiting time, average transfer delay and average queue length are used for measure of performance (MOP). Simple round robin (RR) scheduling policy with exhaustive service is used for the analysis. Packet loss is considered because of noise environments of wireless communication. Numerical results have been presented. Simulation is performed to validate the correctness of analysis.y and its maximum operating frequency is 800MHz.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.5
• /
• pp.772-778
• /
• 2018

Due to the recent advances in computing, communication and micro-electromechanical technology, Wireless Sensor Networks (WSNs) applications have been extended from military to many commercial areas such as object tracking, wire detection, and vehicular sensor networks. In some applications bursty data from many sensor nodes may be generated and the generated data from the monitoring area may be sent in a limited time to the final destination, sink node. In this paper, we present a BTF-MAC protocol adequate for WSNs applications in which bursty data packets are required to be transmitted in a limited time. The BTF-MAC is a synchronous duty-cycle MAC protocol and uses a slot-reserved and operational period extension mechanism adapted to the traffics. Our numerical analysis and simulation results show that BTF-MAC outperforms other related protocols such as DW-MAC and SR-MAC in terms of energy consumption and transmission delay.

• Archives of design research
• /
• v.12 no.2
• /
• pp.97-106
• /
• 1999

The whole crisis of human being derived from environmental pollution has changed the human -centered paradigm into the ecological paradigm based on the harmony of human and nature, which have made it inevitable for designers to participate in the environmental problem-solving. In the line of this sense, it is necessary for designers to recognize the social and ethical responsibility for environmental pollution and to change into the designing for environment, not for sale itself. In accord with the context above, the purpose of this study is to suggest some clues for resolving environmental problems with the analysis of design for long-selling product, as we call, product durability analysis. That is, this study is under some assumptions that designing durable product and durable product itself are able to extend a product life cycle, delay a product disusing, reduce a rash development competition for new product among companies, mitigate consumption-oriented attitude of consumers, eliminate a waste of resources, and go far toward the environmental problem solving.

• Journal of Power Electronics
• /
• v.16 no.1
• /
• pp.227-237
• /
• 2016

A novel digital current control strategy for digitally controlled DC-DC switching converters, referred to as Adjacent Cycle Sampling (ACS), is proposed in this paper. For the ACS current control strategy, the available time interval from sampling the current to updating the duty ratio, is approximately one switching cycle. In addition, it is independent of the duty ratio. As a result, the contradiction between the processing speed of the hardware and the transient response speed can be effectively relaxed by using the ACS current control strategy. For digitally controlled buck DC-DC switching converters with trailing-edge modulation, digital current control algorithms with the ACS control strategy are derived for three different control objectives. These objectives are the valley, average, and peak inductor currents. In addition, the sub-harmonic oscillations of the above current control algorithms are analyzed and eliminated by using the digital slope compensation (DSC) method. Experimental results based on a FPGA are given, which verify the theoretical analysis results very well. It can be concluded that the ACS control has a faster transient response speed than the time delay control, and that its requirements for hardware processing speed can be reduced when compared with the deadbeat control. Therefore, it promises to be one of the key technologies for high-frequency DC-DC switching converters.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.18 no.6
• /
• pp.60-75
• /
• 2019

Nowadays, interest in safety of pedestrians who are relatively weak when compared with vehicles increases. Also, concern for pedestrian accidents on crosswalks increases. For these reasons, scrambled crosswalks which are considered to contribute pedestrian safety by reducing conflicts between vehicles and pedestrians are actively discussed and there are also a few intersections where they are actually installed. However, scrambled crosswalks must include all-red phase for all vehicle traffic flows, which inevitably leads to increase of lost time per cycle. Therefore, evaluation in terms of efficiency should be done before installation of scrambled crosswalks. This research suggests installation criteria for scrambled crosswalks so that it is possible to judge whether installation of scrambled crosswalks is appropriate only by surveying vehicle traffic volume and pedestrian traffic volume. This research derives optimum cycle length from signal optimization models which considers both vehicle traffic volume and pedestrian traffic volume. From this optimum cycle length, this research compares total delay time before and after installation of scrambled crosswalks. From an analysis, two research results are derived. Firstly, there is critical traffic volume above which installation of scrambled crosswalks can not efficient. Secondly, appropriate areas for installation of scrambled crosswalks are different by each signal intersection or by each signal system and those difference vary. From these results, this research suggests installation criteria for scrambled crosswalks which consists of two steps. The delay time of the pedestrians may be increased after the diagonal crosswalk is installed, but it may be desirable to install in consideration of the appropriate traffic level to ensure safety.