• Journal of Mechanical Science and Technology
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• v.19 no.8
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• pp.1670-1681
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• 2005

In-situ diagnosis of chiller performance is an essential step for energy saving business. The main purpose of the in-situ diagnosis is to predict the performance of a target chiller. Many models based on thermodynamics have been proposed for the purpose. However, they have to be modified from chiller to chiller and require profound knowledge of thermodynamics and heat transfer. This study focuses on developing an easy-to-use diagnostic technique that is based on adaptive neuro-fuzzy inference system (ANFIS). The effect of sample data distribution on training the ANFIS is investigated. It is found that the data sampling over 10 days during summer results in a reliable ANFIS whose performance prediction error is within measurement errors. The reliable ANFIS makes it possible to prepare an energy audit and suggest an energy saving plan based on the diagnosed chilled water supply system.

• The Transactions of the Korea Information Processing Society
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• v.6 no.6
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• pp.1598-1608
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• 1999

Performance testing for ATM network deals with evaluation of maximal throughput of network by measuring and analyzing of various performance parameters. However, because of the absence of the methodology and framework for performance testing, the results of performance measurements for same implementation under test were much relied on tester. In this paper, the concept of ATM performance testing is described in both cell and frame level and a framework of ATM performance testing is suggested by describing of testing environment for performance measurement and requirements of performance evaluation. For this, we define performance measuring method and parameters for each case.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.141-150
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• 2013

Simulation is an important technique to test and verify routing protocol correctness. However, simulation does not guarantee that the protocol works expectedly on a real world environment because it needs to rely on assumptions and simplified properties such as radio characteristics and effects of geographical constraints that may not reflect the real world networking environments. Therefore, a real world experiments are necessary to gain a practical insight into the actual performance of ad hoc networks. In this paper, we build a test-bed to evaluate multi-hop ad hoc networks for high speed video streaming inside a building using AODV-UU routing protocol. Our observation indicates that the considered ad hoc network can provide a sufficient performance for a low rate streaming data in terms of throughput, PDR (Packet delivery ratio) and the average delay.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.663-670
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• 2019

Corrective thermal performance analysis is required for power plants' turbine cycles to determine the performance status of the cycle and improve the economic operation of the power plant. We developed a sectional classification method for the main feed-water flow to make precise corrections for the performance analysis based on the Performance Test Code (PTC) of the American Society of Mechanical Engineers (ASME). The method was developed for the estimation of the turbine cycle performance in a classified section. The classification is based on feature identification of the correlation status of the main feed-water flow measurements. We also developed predictive algorithms for the corrected main feed-water through a Kernel Regression (KR) model for each classified feature area. The method was compared with estimation using an Artificial Neural Network (ANN). The feature classification and predictive model provided more practical and reliable methods for the corrective thermal performance analysis of a turbine cycle.

• The KIPS Transactions:PartC
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• v.12C no.6 s.102
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• pp.817-826
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• 2005

BcN(Broadband convergence Network) is being developed in order to support a variety of network applications, with enhanced capabilities of QoS(Quality of Service) provisioning and security, and IPv6. In a high-speed network environment such as BcN, it if more likely for the network resources to be exposed to various intrusion activities. The propagation speed of intrusion is alto expected to be much faster than in the existing Internet In this paper, we present a multi-domain security management framework which my be used for a global intrusion detection at multiple domains of BcN and describe its characteristics. For the performance evaluation, we first present test results for the security node and compare with other products. Then we design and Implement an OPNET simulator for the proposed framework, and present some simulation results. In the simulation model, we focus on the performance of alert information in the security overlay network.

• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.721-730
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• 2001

Nowadays corporation networks are growing rapidly and they are needed to communicate with branch offices. Therefore, a VPN (Virtual Private Network) appears to reduce the cost of access and facilitate to manage and operate the enterprise network. Along with this trend, many studies have been done on VPN. It is important that the performance issues should be considered when VPN protocols are applied. However, most of them are limited on the tunneling methods and implementation of VPN and a few studies are performed on how installation of VPN affects the network. Therefore, in this paper, a testbed is constructed and VPN protocols are installed on it. Real traffic is generated and transmitted on the testbed to test how installing a VPN affects the network. As a result, layer 3 VPN protocol shows lower network performance than layer 2 VPN protocols. And we realize that the combination of L2TP and IPSec is the better method to install VPN than using IPSec only in the aspects of performance and security.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.745-748
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• 1996

Korea Composite Stock Price Index (KOSPI) was predicted using Cascade Correlation Network (CCN) model. CCN was suggested, by Fahlman and Lebiere [1990], to overcome the limitations of backpropagation algorithm such as step size problem and moving target problem. To test the applicability of CCN as a function approximator to the stock price movements, CCN was used as a tool for univariate time series analysis. The fitting and forecasting performance fo CCN on the KOSPI was compared with those of Multi-Layer Perceptron (MLP).

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.293-295
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• 1993

In this paper, Neural-Network Identifier that has time-delay element, error limit and small weighting factor is proposed. A proposed identifier has good performance to identify non-linear system with noise. To test the effectiveness of the algorithm presented above, the simulation for output tracking of non-linear system is implemented.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.1135-1139
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• 1989

Three layered neural network was applied for the pattern recognition problem of human spermatozoa in clinical test. The goodness of recognition rate was studied in relation to the number of hidden layer cells and of output layer cells. The proposed method provided better results than conventional template matching technique. Parallel processing of the back propagation learning algorithm was also studied using transputers and its performance was evaluated.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.4
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• pp.54-63
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• 2011

An educational network system based on CAN protocol internal to a passenger ground vehicle has been developed. The developed network system has been applied to a commercial plug-in electrical vehicle and verified the educational applicability. To apply this in-vehicle network technology based on CAN, a suitable electric vehicle has been chosen and a CAN network structure has been designed, developed and manufactured. Since the commercial electric vehicle chosen as a test bed has its own proprietary electric network, we explain how the original electric network has been utilized and how the new network system has been designed. The developed network system on a real vehicle has been tested to show the applicability and the performance. Finally, the system has been applied at few classrooms to demonstrate how the in-vehicle network system works and to teach how to analyse the CAN signals. The developed system proven to be effective for educational purpose.