• Proceedings of the Korean Society of Computer Information Conference
• /
• 2019.07a
• /
• pp.243-244
• /
• 2019

본 논문에서는지속 가능한 IoT Platform을 개발 하였다. 개발된 IoT(Internet of Things) Platform은 센서를 제어하는 특정 시스템과의 통신을 통한 제어 및 데이터 전달에 용이하고, 제한된 통신 환경 및 낮은 전력에서도 지속적인 작동이 가능하여 가용성(Availability)과 확장성(Extensibility)이 뛰어나다. 본 논문에서는 지속 가능한 IoT Platform의 테스트를 위해 클라우드 컴퓨팅 플랫폼인 AWS EC2(Amazon Elastic Compute Cloud, EC2)에 구축하였으며, DataBase 서버로는 오픈 소스 관계형 데이터베이스 관리 시스템인 MariaDB를 선정하였으며, 센서를 제어하는 특정 시스템인 스마트 미러 시스템(Smart Mirror System)과 미세먼지 제어 시스템(Air Quality Control System)에 기존의 Google IoT Platform에서 사용되는 MQTT Protocol(Message Queuing Telemetry Transport Protocol)와 지속 가능한 IoT Platform를 위해 개발된 TCP/IP Protocol를 사용하여 비교했다. 개발된 IoT Platform은 UTM(Unmanned Aircraft System Traffic Management)으로 확장할 계획이다.

• Journal of Korea Port Economic Association
• /
• v.26 no.3
• /
• pp.42-55
• /
• 2010

This paper primarily deals with a decision-making for determining the number of voyages in each ship size under a specific port structure in order to minimize the total transport cost consisting of transport cost at sea, queuing cost in port, and inventory cost in yard. As a result of computer simulation using queuing model characterized by inter-arrival time distribution, we were able to find out some combination of voyage numbers of 3 ship-size(50,000-ton, 100,000-ton, and 200,000-ton), where the total transport cost can be minimized under a specific port structure. The simulation model also allows us to figure out any trade-off relationship among sea transport cost, queuing cost in port, and inventory cost in yard. Put it differently, an attempt to reduce the sea transport cost by increasing the number of voyages of the largest ship size, the transport cost incurred in both port and yard is hypothesized to be increased and vice versa. Consequently, Port managers are required to adjust the number of annual number of voyages allocated in each ship size, put into the sea lines for importing raw materials, in order to optimize the transport costs incurred under the specific port system. We may consider a net present value(NPV) model for performing an economic feasibility analysis on port investment project. If a total discounted net benefit, including cost savings, exceeds the initial investment for an additional berth construction, then we accept the port investment project. Otherwise, we reject the proposed port investment plan.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.11
• /
• pp.4436-4452
• /
• 2015

The IEEE 802.15.6 standard is introduced to satisfy all the requirements for monitoring systems operating in, on, or around the human body. In this paper, analytical models are developed for evaluating the performance of the IEEE 802.15.6 CSMA/CA-based medium access control protocol for wireless body area networks (WBAN) under unsaturation condition. We employ a three-dimensional Markov chain to model the backoff procedure, and an M/G/1/K queuing system to describe the packet queues in the buffer. The throughput and delay performances of WBAN operating in the beacon mode are analyzed in heterogeneous network comprised of different user priorities. Simulation results are included to demonstrate the accuracy of the proposed analytical model.

• ETRI Journal
• /
• v.19 no.4
• /
• pp.344-362
• /
• 1997

The delay which is one of the quality of service parameters is considered to be a crucial factor for the effective usage of real-time audio and video streams in interactive multimedia collaborations. Among the various causes of the delay, we focus in this paper on the local delay concerned with the schemes which handle continuous inflow of encoded data from constant or variable bit-rate audio and video encoders. We introduce two kinds of implementation approaches, pull model and push model. While the pull model periodically pumps out the incoming data from the system buffer, the push model receives events from the device drivers. From our experiments based on Windows NT 3.51, it is shown that the push model outperforms the other for both constant and variable bit-rate streams in terms of the local delay, when the system suffers reasonable loads. We interpret this experimental data with M/G/1 multiple vacation queuing theories, and show that it is consistent with the queuing theoretic interpretations.

• The KIPS Transactions:PartA
• /
• v.12A no.2 s.92
• /
• pp.117-126
• /
• 2005

This paper presents an adaptive processor allocation strategy to reduce fragmentation in a large multi-user multicomputer system. A small number of jobs with unexpectedly large submesh allocation requirements may significantly increase the queuing delay of the rest of jobs. Under such circumstances, our strategy further tries to allocate L-shaped submeshes instead of signaling the allocation failure unlike other strategies. We have developed the efficient algorithm to find the allocatable L-shaped submeshes. Thus, our strategy reduces the mean response time by minimizing the queuing delay, even though jobs are scheduled in an FCFS to preserve fairness. The simulations show that our strategy performs more efficiently than other strategies in terms of the job response time and the system utilization.

• Proceedings of the IEEK Conference
• /
• 1998.06a
• /
• pp.769-772
• /
• 1998

This paper present an efficient techniques for visual inspection of taped electronic parts, suitable for real time implementation. The main environments of developed system are IBM-compatible personal computer, frame grabber, digital input-output board. It is connected to the programmable logic controller unit of the taping machine in real time. Using a queuing structure, operator or extractor machine can remove easily the defect one from production line. Also, we design a new illumination system for sacquring shape and subface features of object. Therefore, it redue pre-processing step and processing time.

• Proceedings of the IEEK Conference
• /
• 2002.06a
• /
• pp.45-48
• /
• 2002

This paper presents a QoS-guaranteed traffic control system which supports QoS of realtime packet transmission for the multimedia communication. The traffic control system presented in this paper applies the integrated service model and provides QoS o(packet transmission by means of determining the packet transmission rate with the policy of network manager and the optimal resource allocation according to the end-to-end traffic load. It also provides QoS for the realtime packet transmission through the AWF2Q+ Scheduling algorithm and per-class queuing method.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.45 no.4
• /
• pp.53-60
• /
• 2022

In a group-testing method, instead of testing a sample, for example, blood individually, a batch of samples are pooled and tested simultaneously. If the pooled test is positive (or defective), each sample is tested individually. However, if negative (or good), the test is terminated at one pooled test because all samples in the batch are negative. This paper considers a queueing system with a two-stage group-testing policy. Samples arrive at the system according to a Poisson process. The system has a single server which starts a two-stage group test in a batch whenever the number of samples in the system reaches exactly a predetermined size. In the first stage, samples are pooled and tested simultaneously. If the pooled test is negative, the test is terminated. However, if positive, the samples are divided into two equally sized subgroups and each subgroup is applied to a group test in the second stage, respectively. The server performs pooled tests and individual tests sequentially. The testing time of a sample and a batch follow general distributions, respectively. In this paper, we derive the steady-state probability generating function of the system size at an arbitrary time, applying a bulk queuing model. In addition, we present queuing performance metrics such as the offered load, output rate, allowable input rate, and mean waiting time. In numerical examples with various prevalence rates, we show that the second-stage group-testing system can be more efficient than a one-stage group-testing system or an individual-testing system in terms of the allowable input rates and the waiting time. The two-stage group-testing system considered in this paper is very simple, so it is expected to be applicable in the field of COVID-19.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.3 no.2 s.5
• /
• pp.29-40
• /
• 2004

The performance of the National Highway is raised, but the capacity of the signalized intersection on the National Highway is low. It's operated by TOD(Time Of Day) mode. To evaluate of the performance of COSMOS(Cycle, Offset, Split Model for Seoul), a real time traffic adaptive signal control system, on the National Highway, studied volume, travel time and queuing length at TOD control and TRC(Traffic responsive Control). Consequently, the average travel speed at TRC is high $2.9\~16.7$km/h then the average travel speed at TOD control. And te queuing length at TRC is low $15\~196m$ then the queuing length at TOD control.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.10
• /
• pp.73-81
• /
• 2011

The WBAN(Wireless Body Area Network) technology is a short distance wireless network which provides each device's interactive communication by connecting devices inside and outside of body located within 3 meters. Standardization on the physical layer, data link layer, network layer and application layer is in progress by IEEE 802.15.6 TG BAN. The The WBAN servides consists of both medical and non-medical applications. The medical application service uses the sensor that transfer the periodic traffic and have different data rates. It uses GTS method to guarantee QoS. In this paper, a new method is proposed, which are suitable design for MAC Protocol. Firstly, MAC frame structure and a primitive based on the WBAN are proposed. Secondly, we proposed the GTS algorithm improved the channel utilization based on the WFQ(Weighted Fair Queuing). The proposed scheduling method is improved channel utilization compared with i-Game(Round Robin scheduling method).