• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.162-167
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• 2012

In power quality monitoring, it is very important to detect disturbances (sag, swell, transient, and interruption) accurately. In this paper, a detection method for power quality disturbances by combining the filter bank system and adaptive filter is proposed. To decompose power signal, binary tree structured filter bank system is designed. In the filter bank system, the fundamental filter bank(QMF bank) is used as a module in each decomposing level. An adaptive filter is used to improve the detection accuracy of disturbances for each subband signal. In the adaptive filter, the measure of estimated error change is used to detect singular points of power quality disturbances. Computer simulations were performed on synthetic signals which have disturbances to assess the performance of the proposed method.

• Journal of Korea Multimedia Society
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• v.15 no.1
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• pp.115-130
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• 2012

These days, most of safety-critical systems, which are systems those failures or malfunction may result in death or serious injury to people, or loss or severe damage to social systems, or environmental harm, are being built of embedded software or loaded controlling software systems on computers, electrical and electronic components or devices. There are a lot kind of fault analysis methods to evaluate safety of the safety-critical systems equipped computers, electrical and electronic components or devices with software. However, the only assessment method to evaluate software safety of a safety-critical system is not enough to analysis properly on account of the various types and characteristic of software systems by progress of information technology. Therefore, this paper proposes the integrated evaluation method and carries out a case study for the software safety of safety-critical system which embedded or loaded software sizes are small and control response times are not sensitive by use of two security analysis methods which are Fault Tree Analysis (FTA) and Fault Modes and Effect Analysis (FMEA) for ubiquitous healthcare system.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2000.10b
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• pp.60-64
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• 2000

This examination of vegetation is conducted from lune to Oct. 1999 through on the spot survey, centering on the habitat of Abies koreana around Imgeolryeong, langteomok, and Jeseokbong in Mt Jiri and Yeongsil path and Seongpanak path in Mt. Halla. Species composition tables of the Abies koreana community by altitude and slope in Mt. Jiri and Mt. Halla are made based on the community composition tables examined in quadrat. The Abies koreana-Saso quelpaertensis community in a west slope of Mt. Halla is found that Abies koreana of 4-6m in height forms subtree layer and that of 8-9m in height the tree layer and it reflects a difference between community structure by slope and main composition species. While the tree layer of Abies koreana community is 12-14 in height around the area of 1, 290-1, 560m above the sea of Imgeolryong and path from Baekmudong to Jangteomok, it is 8-12m in height in the area of 1, 680-1, 780m above the sea of path from Jangteomok to Jeseokbong. It means that community structure depends on area and attitude. This study finds out that commonly appearing composition species similar to coverage and presence are Lepisorus thunberianus, Quercus mongolica, Soidago virga-aurea var. asiatica, Ligularia fischeri, Carex lanceolata, Clintonia udensis, Magnolia sieboldii, Betula ermani, Acer Pseudo-sieboldianum, As soil environment of surveyed area, pH of surveyed spots is similar in Mt. Jiri and Mt. Halla, electrical conductvity is higher in Mt Jiri, and contents of organic matter is relatively higher in a west slope of Mt. Jiri and Mt. Halla and lower in their south and west slopes. Contents of organic matter and total nitrogen show that the area of 1, 550m above the sea in a west slope of Mt. Halla is some higher. For pH and contents of total nitrogen and organic matter, Mt. Halla is higher than Mt. Jiri but for electrical conductivity , Mt. Jiri is relatively higher than Mt. Halla.

• Plant Resources
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• v.3 no.2
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• pp.138-147
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• 2000

This examination of vegetation is conducted from June to Oct. 1999 through on the spot survey, centering on the habitat of Abies koreana around Imgeolryeong, Jangteomok, and Jeseokbong in Mt Jiri and Yeongsil path and Seongpanak path in Mt. Halla. Species composition tables of the Abies koreana community by altitude and slope in Mt. Jiri and Mt. Halla are made based on the community composition tables examined in quadrat. The Abies koreana-Saso quelpaertensis community in a west slope of Mt. Halla is found that Abies koreana of 4-6m in height forms subtree layer and that of 8-9m in height the tree layer and it reflects a difference between community structure by slope and main composition species. While the tree layer of Abies koreana community is 12-14 in height around the area of 1,290-1,560m above the sea of Imgeolryong and path from Baekmudong to Jangteomok, it is 8-12m in height in the area of 1,680-1,780m above the sea of path from Jangteomok to Jeseokbong. It means that community structure depends on area and attitude. This study finds out that commonly appearing composition species similar to coverage and presence are Lepisorus thunberianus, Quercus mongolica, Solidago virga-aurea var. asiatica, Ligularia fischeri, Carex lanceolata, Clintonia udensis, Magnolia sieboldii, Betula ermani, Acer pseudo-sieboldianum. As soil environment of surveyed area, pH of surveyed spots is similar in Mt. Jiri and Mt. Halla, electrical conductivity is higher in Mt Jiri, and contents of organic matter is relatively higher in a west slope of Mt. Jiri and Mt. Halla and lower in their south and west slopes. Contents of organic matter and total nitrogen show that the area of 1,550m above the sea in a west slope of Mt. Halla is some higher. For pH and contents of total nitrogen and organic matter, Mt. Halla is higher than Mt. Jiri but for electrical conductivity, Mt. Jiri is relatively higher than Mt. Halla.

• Journal of Korea Multimedia Society
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• v.20 no.8
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• pp.1395-1405
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• 2017

In this paper, we analyses heart beat data to identify subjects stress state (binary) using heart rate variability (HRV) features extracted from heart beat data of the subjects and implement supervised machine learning techniques to create the mental stress classifier. There are four steps need to be done: data acquisition, data processing (HRV analysis), features selection, and machine learning, before doing performance measurement. There are 56 features generated from the HRV Analysis module with several of them are selected (using own algorithm) after computing the Pearson Correlation Matrix (p-values). The results of the list of selected features compared with all features data are compared by its model error after training using several machine learning techniques: support vector machine, decision tree, and discriminant analysis. SVM model and decision tree model with using selected features shows close results compared to using all recording by only 1% difference. Meanwhile, the discriminant analysis differs about 5%. All the machine learning method used in this works have 90% maximum average accuracy.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.5
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• pp.662-673
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• 2012

This study introduces a condition diagnosis technique for a turbine governor system. The governor system is an important control system to handle turbine speed in a nuclear power plant. The turbine governor system includes turbine valves and stop valves which have their own functions in the system. Because a turbine governor system is operated by high oil pressure, it is very difficult to maintain under stable operating conditions. Turbine valves supply oil pressure to the governor system for proper operation. Using the pressure variation of turbine and governor valves, operating conditions of the turbine governor control system are detected and identified. To achieve automatic detection of valve status, time-based and frequency-based analysis is employed. In this study, a new approach, wavelet decomposition, was used to extract specific features from the pressure signals of the governor and stop valves. The extracted features, which represent the operating conditions of the turbine governor system, include important information to control and diagnose the valves. After extracting the specific features, decision rules were used to classify the valve conditions. The rules were generated by a decision tree algorithm (a typical simple method for data-based rule generation). The results given by the wavelet-based analysis were compared to detection results using time- and frequency-based approaches. Compared with the several related studies, the wavelet transform-based analysis, the proposed in this study has the advantage of easier application without auxiliary features.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.19-21
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• 2003

In this paper, we studied on life-decision of underground cable of live-lines state. As all equipments have been wear, underground cables decided design-life on the whole 30 years because underground cable have been occurred aging as time goes. CV cable has been become about 30 years after installation in the South Korea, is come to a important point of time with estimation about life. Study target cable is 22 kV CV cables in this point of view and installation cable is about 10 years before and behind. Measurement method used dc leakage method of live-lines state that applied voltage of 50V in neutral point and data is analyzing result that is measured during 5 years. In this result, insulation resistance could confirm that change according to season and cause is effect of humidity, seasons and load current. Also, according as data is gone aging, insulation resistance by Weibull distribution could confirm functionally its decrease. As a result, the aging speed of cable that water tree is gone could confirm fastness very. Numerical analysis result, cable that water tree is not gone could confirm that life of cable that has passed 10 years remains about $10{\sim}20$ years.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.7
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• pp.1624-1637
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• 2013

In RFID systems, one important issue is how to effectively address tag collision, which occurs when multiple tags reply simultaneously to a reader, so that all the tags are correctly identified. However, most existing anti-collision protocols assume isotropic collisions where a reader cannot detect any of the tags from the collided signals. In practice, this assumption turns out to be too pessimistic since the capture effect may take place, in which the reader considers the strongest signal as a successful transmission and the others as interference. In this case, the reader disregards the other collided tags, and in turn, fails to read the tag(s) with weaker signal(s). In this paper, we propose a capture effect-aware anti-collision protocol, called Multi-Round Collision Tree (MRCT) protocol, which efficiently identifies the tags in real RFID environments. MRCT deals with the capture effect as well as channel error by employing a multi-round based identification algorithm. We also analyze the performance of MRCT in terms of the number of slots required for identifying all tags. The simulation results show that MRCT significantly outperforms the existing protocol especially in a practical environment where the capture effect occurs.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.261-263
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• 2005

In this paper, we implement an identification system using the vein image of the hand. The vein pattern is obtained in the grey-scale 2D image through the infrared-red imaging from back of the hand. Since the frame has lack of clearance, we use some enhancing methods such as the complement, addition, and multiplication to the image to increase the contrast. After Wiener filtering for smoothness of the vein pattern, we transform the image into the binary image with mean function. The binarized image is session thinned and the cross-points in the vein tree are obtained by calculating the number of pixels connected because the image is shaped as a tree. We choose the point and find the nearest to the center if it has majority, where we find the two end points of the selected line. We can get the angle between the two lines joined at the cross-point and store its coordinates, angle, and label the values. The values are used as the feature vector of the vein pattern. This procedure is similar to the human cognition sequences. It is shown that the proposed method is simple for the vein recognition.

• Journal of the Korea Computer Industry Society
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• v.3 no.8
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• pp.1039-1048
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• 2002

It is difficult and laborious to distinguish between the original and the plagiarism about the electrical documents or on-line received documents, specially student homeworks because in many case, the homeworks are written on the same subject. Existing methods are not appropriate to solve this problem, which find the most appropriate category using the expression frequency of index term in documents to be classified. In this paper, a new classification method was proposed to distinguish between the original and the plagiarism about documents which were written similarly which is based on the syntagma vector - except the similar syntagma tree structure and non-index term.