• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.6
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• pp.1038-1045
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• 1994

In this paper, algorithm and built-in test circuit for testing all PSF(Pattern Sensitive Fault) occuring in CAM(Content Addressable Memory) are proposed. That is, built-in test circuit that uses minimum additional circuit without external equipment is designed. Additional circuit consist`s of parallel comparator, error detector, and modified decoder for parallel testing. Besides, the study on eulerian path for effectiv test pattern is carried out simultaneously. Consequently, using proposed algorithm, we can test all contents of CAM with 325+2b(b:number of bits) operations regardless of number of words. The area occupied by test circuit is about 7.5% of total circuit area.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.891-893
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• 1997

In this paper an intelligent power transformer protective relaying algorithm based on Fuzzy Decision-Making is presented. The introduced protection algorithm contains several internal fuzzy rule-bases including bpa(Basic Probability Assignment: m) which are subject to off-line pre-installation by the analysis of the transformer transient characteristics for detecting the internal fault. Dempster-Shafer's rule of combination is used for the inference method with rules to decide the situation of a transformer, The proposed algorithm immunes to the saturation of transformer, inrush conditions, over excitation, and external fault. The included results of testing show practically sufficient sensitivity and selectivity of the proposed algorithm.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1729-1738
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• 2014

The offline verification of state of charge estimation, power estimation, fault diagnosis and emergency control of battery management system (BMS) is one of the key technologies in the field of electric vehicle battery system. It is difficult to test and verify the battery management system software in the early stage, especially for algorithms such as system state estimation, emergency control and so on. This article carried out the virtual environment modeling for verification of battery management system. According to the input/output parameters of battery management system, virtual environment is determined to run the battery management system. With the integration of the developed BMS model and the external model, the virtual environment model has been established for battery management system in the vehicle's working environment. Through the virtual environment model, the effectiveness of software algorithm of BMS was verified, such as battery state parameters estimation, power estimation, fault diagnosis, charge and discharge management, etc.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.218-226
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• 2017

In this paper, optical transport network in real time monitoring system using smart phone. The existing housing using monitoring was a smart phone of optical transport network access switch about an event with new installation of cognitive system in real time. This paper can this problem to be solved of the invention in real time maintenance using smart phone application and optical cable closure switch. If you want to find optical cable closure fault location, this smart phone web is very useful. Cable tie is isolation of fiber spare board from fiber switch tie occur push message. Housing and access, and an external failures otdr the measurement of the global positioning to be able to easily using the This paper can find event of optical cable closure unauthorized work and fault using smart phone OTDR function. the optical cable fault time reduction and network transport quality by managing real time optical cable section by using the smart phone can be maintained efficiently.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.394-399
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• 2017

In Korean AC power railway substations, SCOTT winding transformers are under operation to have a single phase power supply together with a phase angle of $90^{\circ}$ on the secondary side of the main transformer. In the case of an internal fault of the transformer, the transformer protection relay should be cut off on the primary side, the transformer should be inoperative to the external fault of the transformer or to the normal train operation. Reducing the malfunction of the relay through an exact fault determination is very important for securing a stable power system and improving its reliability. The main transformers are protected using Buchholtz's relay and a differential relay as the internal fault detection devices, but there are some cases of the main transformer operation under the deactivation of this protection function due to a malfunction of the differential relay. In this paper, the characteristics of the SCOTT transformer and differential relay as well as the malfunctioning of the protection relays are presented. The modeling of the SCOTT transformer protection relay was accomplished by the power system analysis program and the Comtrade file from 'A substation', which was used as the input data for the fault wave, and the harmonics were analyzed to determine if the relay operates or not. In addition, an improvement plan for malfunctioning cases through wave form analysis is suggested.

• Journal of Mechanical Science and Technology
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• v.18 no.9
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• pp.1537-1548
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• 2004

This paper presents a novel diagnostic technique for monitoring the system conditions and detecting failure modes and precursors based on wavelet-packet analysis of external noise/vibration measurements. The capability is based on extracting relevant features of noise/vibration data that best discriminate systems with different noise/vibration signatures by analyzing external measurements of noise/vibration in the time-frequency domain. By virtue of their localized nature both in time and frequency, the identified features help to reveal faults at the level of components in a mechanical system in addition to the existence of certain faults. A prima-facie case is made via application of the proposed approach to fault detection in scroll and rotary compressors, although the methods and algorithms are very general in nature. The proposed technique has successfully identified the existence of specific faults in the scroll and rotary compressors. In addition, its capability of tracking the severity of specific faults in the rotary compressors indicates that the technique has a potential to be used as a prognostic tool.

• Journal of Wind Energy
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• v.13 no.3
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• pp.33-42
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• 2022

In this paper, a semi-supervised machine learning technique applied to actual field vibration data acquired from Jeju-do wind turbines for predictive diagnosis of abnormal conditions of offshore wind turbines is introduced. Semi-supervised machine learning, which combines un-supervised learning with supervised learning, can be used to perform anomaly detection in situations where sufficient fault data cannot be obtained. The signal processing results using the spectrogram of the original signal were shown, and external data were used to overcome the problem that disturbance reactions easily occurred due to the imbalance between the number of normal and abnormal data. Out of distribution (OOD), which uses external data, is a technology that is regarded as abnormal data that is unlikely to occur in reality, but we were able to use it by expanding it. By rearranging the distribution of data in this way, classification can be performed more robustly. Specifically, by observing the trends of the abnormal score and the change in the feature of the representation layer, continuous learning was performed through a mixture of existing and new data.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.13 no.1
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• pp.253-266
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• 2000

In order to strengthen objectivity and availability of oriental herb medicine, the standard formula for herbs has been attempted to set up by experimenting and documentary testing original herbs which were recorded in authorized document. The object herb medicine is Codonopsis Pilosulae Radix. The internal and external morphological standard in this study is expected to supply the search for several physiochemical reaction, biological reaction, determination of indicator material and identification of gene with basic sources in the future. The result of study is as follows; In the external shape, it was possible that herbs were distinguished according to artificial classification and that same genus-degree of relatedness among herbs could be distinguished by more precise and active observation. In the shape of real herbs, I compared current herbs in market with original herbs which were just collected or were on the course of drying. In addition, it was possible that the internal shape could be identified by using microscope after butanol series. In powder herbs, it was possible to purify the shape by microscope through maceration of natural and powder herbs. Though it was impossible to make distinction of herbs which are not current in my search contents, this search contents will be a standard for alpplying herbs in the future. Despite such a useful character, it was difficult to deal with power herbs because it was uncertain to make a standard for them on account of the crush of these tissue. Since powders shape of herbs in a few documents were regard not as the powder shapes of natural herbs but as the maceration state of them. It is suggested that we should inspect the original herbs which are not crushed yet with a microscope in order to identify crushed shape of powder herbs from now on. An Additional standard establishment including physiochemical reaction and gene research is required in order to supplement the fault of this search. As for the supplement about this search, considering that many kinds of same genus-degree of relatedness are being current now, it is necessary that each herb should he collected only after identifying and that the succeeding search of each herb should be proceeded for the regular establishment of internal and external standard.

• Journal of the Korean Society of Safety
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• v.35 no.1
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• pp.107-115
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• 2020

This paper introduces the first vital area identification (VAI) process for the physical protection of nuclear power plants (NPPs) during low power and shutdown (LPSD) operation. This LPSD VAI is based on the 3rd generation VAI method which very efficiently utilizes probabilistic safety assessment (PSA) event trees (ETs). This LPSD VAI process was implemented to the virtual NPP during LPSD operation in this study. Korea Atomic Energy Research Institute (KAERI) had developed the 2nd generation full power VAI method that utilizes whole internal and external (fire and flooding) PSA results of NPPs during full power operation. In order to minimize the huge burden of the 2nd generation full power VAI method, the 3rd generation full power VAI method was developed, which utilizes ETs and minimal PSA fault trees instead of using the whole PSA fault tree. In the 3rd generation full power VAI method, (1) PSA ETs are analyzed, (2) minimal mitigation systems for avoiding core damage are selected from ETs by calculating system-level target sets and prevention sets, (3) relatively small sabotage fault tree that has the systems in the shortest system-level prevention set is composed, (4) room-level target sets and prevention sets are calculated from this small sabotage fault tree, and (5) the rooms in the shortest prevention set are defined as vital areas that should be protected. Currently, the 3rd generation full power VAI method is being employed for the VAI of Korean NPPs. This study is the first development and application of the 3rd generation VAI method to the LPSD VAI of NPP. For the LPSD VAI, (1) many LPSD ETs are classified into a few representative LPSD ETs based on the functional similarity of accident scenarios, (2) a few representative LPSD ETs are simplified with some VAI rules, and then (3) the 3rd generation VAI is performed as mentioned in the previous paragraph. It is well known that the shortest room-level prevention sets that are calculated by the 2nd and 3rd generation VAI methods are identical.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3512-3517
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• 2007

Nuclear power plant has many external fire hydrants that have to operate in the state of emergency such as facility fire, forest fire. The valve stem of one among them was broken 3 times for 4 years. It had long valve stem and operated under high water pressure. The elongation and the tensile strength for the broken valve stem was measured to examine the defect of material property. And the vibration level and the natural frequencies was detected to check the resonance. As the result of a diagnosis, the cause of this fault is proven buckling of long valve stem.