• 전기학회논문지
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• 제61권1호
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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.

• 한국멀티미디어학회논문지
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• 제15권1호
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• pp.115-130
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• 2012

오늘날 대다수의 안전필수 시스템들(Safety-Critical Systems)에는 컴퓨터, 전기 및 전자 부품이나 장치들에 소프트웨어를 칩에 내장하거나 제어용 소프트웨어 시스템이 탑재되어 구축되고 있다. 이에 따라, 컴퓨터 소프트웨어를 내장하였거나 탑재한 시스템들의 안전성을 평가하기 위한 여러 가지의 결함 분석 기법들이 제안되어져 오고 있다. 이러한 소프트웨어 결함 분석 기법들은 전통적으로는 하나의 안전필수 시스템을 분석하는데 단지 하나의 방법으로만 분석해 왔으나, 시스템의 종류와 특성이 다양해지면서 그 시스템에 가장 알맞은 결함 분석 기법이 동원되어야 함은 필수적이다. 본 연구에서는, 안전필수 시스템에서 소프트웨어의 크기가 비교적 작고, 안전성과 관련한 시스템 제어 반응 시간이 특별히 민감하지 않는 소프트웨어의 안전성을 평가하는 방법으로 결함트리 분석(FTA)과 소프트웨어 고장 유형 및 영향 분석(FMEA)을 결합한 시스템 결함 분석 방법을 제안하고 유비쿼터스 헬스케어 시스템을 이용하여 사례연구를 수행하고자 한다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2000년도 제7차 국제 심포지움(생약자원개발에 관한연구) 및 추계정기 학술발표회 초록집
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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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• 제3권2호
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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.

• 한국멀티미디어학회논문지
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• 제20권8호
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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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• 제36권5호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기물성,응용부문
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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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• 제7권7호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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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.

• 한국컴퓨터산업학회논문지
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• 제3권8호
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• pp.1039-1048
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• 2002

전자문서와 온라인으로 수신된 문서들은 표절 여부를 판별하기가 매우 어렵고 번거로운 일이다. 특히 학생들에게 부여된 과제물의 경우 동일한 주제에 대해서 작성되는 경우가 많으므로 독자적으로 작성된 문서와 표절되어진 문서를 판별하기가 쉽지 않다. 이것은 분류하고자 하는 문서들에서 주요 단어들 즉, 색인어들의 출현 빈도를 추출한 뒤 이를 이용하여 가장 적합한 카테고리를 찾는 기존의 방법들과는 전혀 다른 문제이다. 본 논문에서는 어절들의 -유사 어절 트리 구조와 색인어를 제외한 어절- 벡터를 기반으로 하여 비슷하게 작성된 문서들의 표절 판별을 목적으로 하는 작업에 적용될 수 있는 방법을 제안한다.