• 전기학회논문지P
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• 제66권1호
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• pp.33-37
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• 2017

This paper describes the modeling of the failure rate estimation technique for applying the asset management technique to electric power facilities. There are many modeling techniques to estimate the failure rate. In this paper, the characteristics of the normal distribution, exponential distribution, weibull distribution, and piecewise linear functions are discussed. When evaluating reliability, the evaluation may be less meaningful if the sample data is insufficient. Therefore, Weibull distribution and piecewise linear function are adopted as the most suitable functions for estimating the failure rate of power facilities and the resulting failure rate function is derived.

• 음성과학
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• 제10권3호
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• pp.225-239
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• 2003

In this paper, we develop a keyword spotting system using vocabulary-independent speech recognition technique, and investigate several non-keyword modeling and post-processing methods to improve its performance. In order to model non-keyword speech segments, monophone clustering and Gaussian Mixture Model (GMM) are considered. We employ likelihood ratio scoring method for the post-processing schemes to verify the recognition results, and filler models, anti-subword models and N-best decoding results are considered as an alternative hypothesis for likelihood ratio scoring. We also examine different methods to construct anti-subword models. We evaluate the performance of our system on the automatic telephone exchange service task. The results show that GMM-based non-keyword modeling yields better performance than that using monophone clustering. According to the post-processing experiment, the method using anti-keyword model based on Kullback-Leibler distance and N-best decoding method show better performance than other methods, and we could reduce more than 50% of keyword recognition errors with keyword rejection rate of 5%.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.774-778
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• 1996

Developed in this research is a surface modeling kernel for various CAD/CAM applications. Its internal surface representations are rational parametric polynomials, which are generalizations of nonrational Bezier, Ferguson, Coons and NURBS surface, and are very fast in evaluation. The kernel is designed under the OOP concepts and coded in C++ on PCs. The present implementation of the kernel supports surface construction methods, such as point data interpolation, skinning, sweeping and blending. It also has NURBS conversion routines and offers the IGES and ZES format for geometric information exchange. It includes some geometric processing routines, such as surface/surface intersection, curve/surface intersection, curve projection and so forth. We are continuing to work with the kernel and eventually develop a B-Rep based solid modeler.

• 전력전자학회논문지
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• 제20권4호
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• pp.344-350
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• 2015

A battery management system requires accurate information on the battery state of charge (SOC) to achieve efficient energy management of electric vehicle and renewable energy systems. Although correct SOC estimation is difficult because of the changes in the electrical characteristics of the battery attributed to ambient temperature, service life, and operating point, various methods for accurate SOC estimation have been reported. On the basis of piecewise linear (PWL) modeling technique, this paper proposes a simple SOC observer for lithium-polymer batteries. For performance evaluation, the SOC estimated by the PWL SOC observer, the SOC measured by the battery-discharging experiment and the SOC estimated by the extended Kalman filter (EKF) estimator were compared through a PSIM simulation study.

• 한국철도학회논문집
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• 제3권2호
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• pp.43-50
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• 2000

The corrugated panels are the prime candidate structure for the floor, roof and wall of Korean high speed train. The equivalent continuum modeling approach panels can be used for the efficient design and evaluation of their structural characteristics. The equivalent continuum models, derived from the true complex corrugated panels, should have the same structural behavior as the original structures have. This paper briefly reviews three representative continuum modeling methods: the static analysis method and two plate-models based on modal analysis methods (MAM). These methods are evaluated through some numerical examples by comparing the natural frequencies and static deflections. It is observed that the plate-model based on Rayleigh-Ritz method seems to provide the best results when used in conjunction with the cantilever-type boundary conditions. The equivalent elastic constants of various corrugated panels, depending on the changes in their configurations, are tabulated for efficient use in structural design.

• 한국안전학회지
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• 제18권3호
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• pp.39-45
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• 2003

The failure mode of a pipe due to local wall thinning is increasingly more attention in the nuclear power plant industry. To assess the integrity of locally wall thinned pipe, it is necessary to perform many simulations under various conditions. Because the modeling for locally wall thinned elbow is more complicated than that of straight pipe the efficient modeling method for finite element analysis is necessary. In this study, the more simple efficient modeling method of three-dimensional finite element analysis for locally wall thinned elbow has been suggested and verified. And using the method, the failure mode of local wall thinned elbows that have different thinning lengths and circumferential angles is evaluated. From the results, we concluded that the collapse load of elbows has been decreased by the increase of wall thinning shape factors such as thinning lengths and circumferential angles.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1699-1701
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• 2005

Islanding phenomenon is undesirable because it lead to a safety hazard to utility service personnel and may cause damage to power generation and rower supply facilities as a result of unsynchronized reclosure. In order to prevent this phenomenon, various anti-islanding methods have been studied. Even though the slip mode frequency shift(SMS) method has been regarded as a highly effective anti-islanding method, the analytical design method of that was not cleared. This paper proposes a modeling of the SMS method using non-detection tone(NDZ) and evaluation of the method according to the test conditions of IEEE Std. 929-2000. The SMS method is derived analytically through modeling and verified visually by simulation and experiment.

• 한국산업융합학회 논문집
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• 제23권4_2호
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• pp.661-667
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• 2020

The optimal shape modeling of core parts through 3D modeling and structural analysis for the development of small and medium-sized ships. The goal is to improve the efficient structure of the hydraulic system for controlling the rudder among the core steering parts in small and medium-sized ships. Through 3D modeling and structural analysis, a new concept of tiller parts and a double-acting hydraulic cylinder control system were proposed and operational structural stability was evaluated. Structural analysis of the three different tiller designs that can be replaceable onto existing fishing vessels was conducted to derive the final shapes. The emphasis was placed on evaluating the structural stability of the key drive components, the tiller, pin, and cylinder rodin the maximum torque condition of the hydraulic cylinder.

• 융합신호처리학회논문지
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• 제12권2호
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• pp.119-127
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• 2011

The paper surveys various analytical models for IEEE 802.11 medium access control protocols and critically discusses recent issues developing in wireless mobile ad hoc networks and their MACs. The surveyed MAC protocols include the standard IEEE 802.11 MAC suites such as IEEE 802.11 DCF, IEEE 802.11 PCF, IEEE 802.11e EDCA, and IEEE 802.11 ad hoc mode; and also the newer, de facto MAC protocols. We study the analytic models of the standard MAC suites followed by the newer analytic models that have been published in recent years. Also, the paper tries to include most of current literatures discussing analytic modeling of MAC in conjunction to some critical issues such as contention among ad hoc nodes, hidden terminal problems, and real-time service support.

• 한국시뮬레이션학회논문지
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• 제11권1호
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• pp.71-82
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• 2002

One of the most important things in the research for MIN-based switch operation the management scheme of network cycle. In the traditional MIN, when the receving buffer module is empty, the sell has to move forward the front-most buffer position by the characteristic of the conventional FIFO queue. However, most of buffer modules are almost always full for practical amount of input loads. The long network cycle of the traditional scheme is thus a substantial waste of bandwidth. In this paper, we propose the modeling method for the input and multi-buffered MIN with unit step buffering scheme, In spite of simplicity, simulation results show that the proposed model is very accurate comparing to previous modeling approaches in terms of throughput and the trend of delay.