• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.289-291
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• 2003

IP멀티캐스트가 현재 보편적 서비스로 사용되지 못하는 한계로 인하여 그 대안으로 응용 계층 멀티캐스트 기법들이 제안되고 있다. 기존의 응용 계층 멀티캐스트의 성능 분석 기준으로 네트워크 자원의 효율적 사용면을 고려하여 스트레스, 스트레치와 전송 트리 관리 비용등이 사용되었다. 그러나, 응용 계층 멀티캐스트는 데이터의 전송이 참가자인 종단 시스템에 의해 이루어지고, 종단 시스템은 범용 장비로서 데이터 전달에 최적화된 성능을 갖지 못한다. 따라서, 데이터 전달을 위해 종단 시스템에서의 처리 지연이 발생하고 이로 인한 종단간 데이터 전송 지연에 영향을 끼치게 된다. 본 논문에서는 종단 시스템에서의 데이터 전달을 위한 전달 지연 시간을 모델링 하고, 대표적 다대다 응용 계층 멀티캐스트 기법인 End­system Multicast와 NICE에 대하여 종단 시스템에서 발생하는 처리 지연 시간이 전체 참가자간의 데이터 전송 지연 시간에 미치는 영향을 분석한 결과를 기술한다.

• Journal of KIISE:Information Networking
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• v.27 no.2
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• pp.237-246
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• 2000

A broadband access network in B-ISDN subscriber network, plays a role of concentration or multiplexing of various subscribers into a service node. For call and connection control functions, DSS2 and B-ISUP signalling protocols are standardized for each of a subscriber side and a network node. B-BCC and B-ANCC protocol were proposed for VB5.2 interface. This interface allows dynamic control of ATM connections at the broadband access network. To establish an end-to-end ATM connection, interworking functions between VB5.2 interface's connection control protocol and the signalling protocol, are performed at the service node. A sequential interworking model and a parallel interworking model were proposed for these interworking functions. The sequential interworking model recommended by ITU-T causes an overall connection setup delay by introducing the access network, because this model proceeds the signalling protocol of network node after the response of VB5.2 interface protocol. On the other hand, the parallel interworking model proceeds the signalling protocol and the VB5.2 interface protocol simultaneously. The simultaneity of the parallel interworking model minimizes the overall connection setup delay. In this paper, we analyze and simulate above two interworking models with B-BCC or B-ANCC protocol in terms of a connection setup delay and completion ratio.

• Journal of Internet Computing and Services
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• v.11 no.2
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• pp.1-15
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• 2010

The damage of safety accidents at home can be minimized by preventing accidents in advance as well as by coping with the accidents promptly through the help of safety management system. In this paper, we identify several services to prevent and cope with the accidents that may occur at home by leveraging sensors and wireless network technology available at home network environments. In order to provide these services, we propose a context-aware system for safety management at home. The proposed system awares the dangerous situations through the information collected by the sensors in home network environment. The proposed system tries to not only prevent the accidents but also to cope with the situations using the information of rescue targets and the location where the accident occurs. We evaluate the appropriateness of sensors by implementing the proposed environments. Through OPNET simulation experiments, we also measure the amount of network traffic in order to confirm that the bandwidth of IEEE 802.15.4 is enough for the proposed system. Finally, we determine more appropriate wireless data transmission mechanism with respect to the end-to-end delay and battery consumption for the proposed system.

• Journal of IKEEE
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• v.18 no.3
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• pp.427-434
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• 2014

The Multihop Routing of vehicle communication environment is difficult to maintain due to heavy fluctuation of network topology and routing channel according to the movement of the vehicle, road property, vehicle distribution. We implemented GeoNetworking on the basis of ETSI(European Telecommunication Standard Institute) to maintain the vehicle safety service. GeoNetworking has its own way that delivers the data through the Unicast and Broadcast. In this paper, we compared performance index such as packet delivery ratio, end-to-end delay about GeoNetworking using the QualNet Network Simulator. Previous research assessed performance of GeoUnicast. This research has been additionally performed about GeoBroadcast, and we progressed algorithm performance through the comparison of CBF(Contention based Forwarding) of GeoUnicast with Greedy forwarding of GeoBroadcast.

• Journal of Communications and Networks
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• v.13 no.3
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• pp.286-297
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• 2011

A novel converged optical network unit (ONU)-base station (BS) architecture has been contemplated for next-generation optical-wireless networks. It has been demonstrated through high quality studies that data traffic carried by both wired and wireless networks exhibit self-similar and long range dependent characteristics; attributes that classical teletraffic theory based on simplistic Poisson models fail to capture. Therefore, in order to apprehend the proposed converged architecture and to reinforce the provisioning of tightly bound quality of service (QoS) parameters to end-users, we substantiate the analysis of the QoS behavior of the ONU-BS under self-similar and long range dependent traffic conditions using custom queuing which is a common queuing discipline. This paper extends our previous work on priority queuing and brings novelty in terms of presenting performance analysis of the converged ONU-BS under realistic traffic load conditions. Further, the presented analysis can be used as a network planning and optimization tool to select the most robust and appropriate queuing discipline for the ONU-BS relevant to the QoS requirements of different applications.

• Journal of Construction Engineering and Project Management
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• v.4 no.4
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• pp.47-59
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• 2014

Client organization inadequate project planning before awarding the contract and insufficient monitoring and control system among the parties involved create severe problems. Ultimately, large-scale projects go beyond the expected cost and time control limits. This paper discusses the major issues involved with a large-scale Hydropower Project in Pakistan Public Sector environment. The latest approved Baseline Plan of project was reviewed and analyzed using Variance Analysis and Trend Analysis techniques in Primavera project management software to assess the efforts made of the parties involved. It was found that Project is 202% Cost overrun and 25% time delays from original contract award. After analysis of baseline plan and quantification of various variance issues in impacted activities, the questionnaire survey was conducted to identify the impact of causative factors. There were almost 17 most significant causative factors identified among 60 identified factors and responsibilities are assigned accordingly. At the end recommendations are made for strategic decisions as lessons learned during project evaluation.

• International Journal of Advanced Culture Technology
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• v.8 no.3
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• pp.300-306
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• 2020

This study analyzes the distributor's inventory model in a two-stage supply chain consisting of the supplier, the distributor and the end customer. The supplier will allow a credit period before the distributor settles the account with him in order to stimulate the demand for the product he produces. It is also assumed that the distributor pays the shipping cost for the order and hence, the distributor's ordering cost consists of a fixed ordering cost and the shipping cost that depend on the order quantity. The availability of the delay in payments from the supplier enables discount of the distributor's selling price from a wider range of the price option in anticipation of increased customer's demand. As a result, the availability of a credit transaction leads to an increase in inventory levels. On the other hand, in the case of deteriorating products in which the utility of the product perish over time, the deterioration rate with time plays a role in reducing inventory levels. In this regard, we analyze the effect of the length of the credit period and the degree of product deterioration on the distributor's inventory level. For the analysis, we formulate the distributor's annual net profit and analyze the effect of the length of credit period and deterioration rate of the product on inventory policy numerically.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.4
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• pp.112-118
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• 2013

Air travel demand has recently been growing and establishment and operation of low-cost carriers have been increased. Against this backdrop, low-cost carriers need to figure out diversified customer demand for low-cost carriers and ways to maximize marketing efficiency before applying it to the field so that they can attain superiority to large carriers in increased intensified competition. Low-cost carriers need to be differentiated from other carriers for the purpose of improving profits. Toward this end, this study conducted analysis on importance and satisfaction with carrier choice using IPA with regard to low-cost carrier customers. In conclusion, the paper accurately examined advantages and disadvantages of low-cost carriers compared to general carriers based on results of IPA analysis and suggested managerial strategies to enhance competitiveness based on division into four parts including maintenance and enforcement (1st quadrant, Delay compensation, Booking rapidity, Check rapidity, Crew service, refund service, baggage service, punctuality, transit services, airlines images), concentrated improvement (2nd quadrant, price, Convenience of seat), passive administration (3rd quadrant, Boarding service, cabin cleanliness, flight schedule, whether local crew on board, meal service, in-flight entertainment service), and enhanced satisfaction (4th quadrant, duty-free service, Variety of routes), so that practical suggestions could be presented to employees working in the field.

• Journal of KIBIM
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• v.11 no.3
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• pp.34-44
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• 2021

This study quantitatively analyzes the work performance of the structural safety diagnosis team that diagnoses pipe racks. To this end, a method for evaluating the performance of the structural safety diagnosis team using the queuing model was proposed. For verification, the case of applying the existing method and the method of introducing a 3D laser scanner for one site was used. The period, number of people, and initial investment cost of each project were collected through interviews with case project experts. As a result of analyzing the performance of the structural safety diagnosis team using the queuing model, it was possible to confirm the probability of delay in the work of each project and the amount of delayed work. Through this, the cost (standby cost) when the project was delayed was analyzed. Finally, economic analysis was conducted in consideration of the waiting cost, labor cost, and initial investment cost. The results of this study can be used to decide whether to introduce 3D laser scanners.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.1050-1061
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• 2009

The Tactical Internet(TI) managed by Infantry Brigades is used for the purpose of sharing information of Command Control and Situation Awareness. When there are more than two destinations to transmit data in the TI system, a multicasting is utilized based on pre-defined multicast groups. However even in the case when a source node needs to send some messages like weathercast and attack alarm etc to only a part of Battalion or Brigades in a specific geographical region (destination region), the current TI multicasting protocol is designed to transmit the messages to the pre-defined group or all of the Battalion/Brigade nodes, resulting in inefficiency in terms of end-to-end delay and overhead. In this paper, we propose more efficient protocol for such cases, named as "Tactical Internet Geocasting (TIG)". The proposed scheme firstly checks whether the destination region belongs to one Battalion region or more than two Battalion regions using location information, and then performs a greedy forwarding from the source node to the destination region, followed by a local flooding inside of the destination region. With performance analysis and simulations using NS-2, TIG is compared to the current TI multicasting protocol (i.e., Simplified MDP) and the LBM (Location-based Multicast). The simulation results show that the proposed TIG is more efficient than both in terms of delay and network overhead.