• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.60-61
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• 2006

An unwanted trip of backup distance relays often lead to a blackout. This paper presents investigation report on involvement of backup distance relays in the past blackouts and sensitivity-factor based algorithm to make a distinction between a fault and overload caused by line tripping. A preliminary idea to prevent deterioration of the situation due to unwanted trip of distance relays by utilizing the proposed algorithm is presented.

• Korean Journal of Environment and Ecology
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• v.28 no.3
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• pp.302-313
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• 2014

This study was conducted to compare the characteristics of fish distribution according to sand type stream and cobble type stream the 4 stream selected every season. The collected Korea endemic species during the survey period were 24, including Acheilognathus gracilis. Dominant species of Hongcheon stream and Muju Namdae stream was Zacco koreanus, each accounting for 39.9% and 28.4% in order, and dominant species in Yanghwa stream was Rhodeus notatus, 13.6%, and those in Gap stream was Z. platypus, by 26.0%. As a result of community analysis, dominant index was 0.27~0.63, diversity index was 1.92~2.67, evenness index was 0.6~0.79, richness index was 3.09~3.53, and dominant index was the highest in Hongcheon stream, and the indices of diversity, evenness and richness were the highest in Yanghwa stream. As a result of tolerance guild analysis, Hongcheon stream and Muju Namdae stream with a variety of substrates accounted for relatively higher rate by 50.1% and 46.4% in sensitive species respectively, and Yanghwa stream and Gap stream with greater sand substrates had 0.5% and 5.3% scarce rate of sensitive species. As a result of similarity analysis using the species, population and substrate structures of the fisheries appeared in each stream, cobble type streams such as Hongcheon stream and Muju Namdae stream were the most similar by 50.4% in species and population, 95.2% in bed structure. As a result of IBI analysis, Hongcheon stream and Muju Namdae stream appeared as 'Class A,' Yanhwa stream and Gap stream as 'Class B' and the two groups of cobble type stream and sand type stream were divided as a result of principal components analysis.

• Korean Journal of Environmental Biology
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• v.35 no.2
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• pp.105-115
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• 2017

The present study is to understand the Bongseonsa stream in the National Arboretum fish fauna variation through comparison with historical data and to evaluate the stream health situated. We performed investigations over three times from April to September 2015. In the survey, 2,960 individuals which belonging to 22 species, 8 families were collected. Dominant species by number was Zacco platypus and subdominant species was Zacco koreanus. Seven Korean endemic species (Squalidus gracilis majimae, Microphysogobio yaluensis, Zacco koreanus, Koreocobitis rotundicausata, etc) were observed and showed a ratio of 36.4%. The community analysis revealed that the structure of fish community in the study sampling sites was instability in having dominance 0.79 (${\pm}0.15$), diverse 1.21 (${\pm}0.60$), evenness 0.58 (${\pm}0.15$) and species richness 1.49 (${\pm}0.83$). The values in the Qualitative Habitat Evaluation Index (QHEI) was averagely 122.9 (${\pm}44.8$) in the Bongseonsa stream and this was showed to have favorable habitat surroundings. As a result of tolerance guild analysis, the total number of sensitive species and intermediate species were higher than tolerant species. Analysis was divided into A and B two groups of fiducial 12.25% in Cluster analysis degree of similarity between study sampling sites. Fish Assessment Index (FAI) was rated A and B grade in Bongseonsa stream that stream health showed favorable. However Wangsuk stream as a urban stream rated C grade and analysed the lowest grade in the whole study sampling sites. There was high correlation beteween FAI and various indexes, dominance, diverse, evenness and sensitive species and intermediate species.

• Korean Journal of Ecology and Environment
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• v.47 no.spc
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• pp.100-115
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• 2014

For this study, we collected fishes of seven times at the 51 sites by stream orders (2-6) from November 2007 to September 2010. In the results, 55 species belonging 12 families were collected. And there were one species (1.8%) of Natural monument, 6 species (10.9%) of endangered and 22 species (40.0%) of Korea endemic. Dominant species was Zacco koreanus and subdominant species was Zacco platypus in whole. Stream orders (2-6) increased with increasing species, diversity (H'), evenness (EI), richness (RI), tolerant (TS), omnivore (OS) and decreasing individual, dominance (DI), sensitive (SS) insectivore (IS), total IBI score. Principal component analysis results showed location of variable (species, individual, community index, relative abundance of tolerant, sensitive, omnivore, insectivore species) and each site changes in upstream and down-stream changes in their distribution. Correlation analysis showed significant differences between stream orders (2-6) and variable (species: Sp, diversity index: H', omnivore species: OS, stream depth: SD, stream width: SW and water temperature: WT).

• Korean Journal of Environment and Ecology
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• v.7 no.2
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• pp.252-269
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• 1994

This study was conducted to the early diagnosis of injuries on needles of conifer by acid rain and air pollutants in metropolitan area, Korea. It was executed to calculate of injured index, contact angle measurement, nutrient content analysis in needles, analysis of soil chemical properties from June 1990 to June 1991. The sensitive species (Picea abies, Abies holophylla) for acid rain and air pollutants were used as the study materials. And the results from this study were as follows : Degree of Injured index was divided into three groups in June 1990. The first group (not injured sites) was Kwangnung and Yangpyung. The Second group (slight injured sites) was Inchon, Boramae Park, Kwachun, Seoul Women's Univ., Anyng, and Yangsuri. The third group (serious injured sites) was Namsan, Seoul City Univ., Children's Park, and Kumgok Royal Tomb. But, Inchon, Kwachon area were changed from slight injured areas to serious injured areas in December 1990. As time goes on, the degree of injured gets worse. In contact angle analysis, value of December 1990 was lower than that of June 1990, especially, that of two-year-needle were lower than of one-year-needle. The correlation between injured Index and contact angle was significantly negative. In the result of needle nutrients analysis of Picea abies, Abies hozophylla, Ca, Mg, K contents was higher in December 1990 than that in June 1991 and that of one-year-needle were prominantly higher than that of two-year-needle. In case of wax quantity analysis in injured area, the older the leaf age is, the smaller the contented wax quantity is. In injured area, the higher a leaf age is, the much that of index is. As a result, the method of analysis referred in the former, is applied by a complementary cooperation. That of method is done sustainably in the future, the correct results will be expected.

• The Korean Journal of Malacology
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• v.11 no.1
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• pp.35-50
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• 1995

저자들은 1994년 7월부터 1995년 2월까지 남해안 마산만의 덕동 지역과 대주군인 자란도 및 이수도에서 오염원의 영향을 민감하게 받는 종을 선별하기 위하여 조간대 및 아조대의 저서동물 군집을 채집하고 정성, 정량적 분석을 실시하였다. 조사결과 덕동 지역 군집은 대조군인 자란도나 이수도에 비하여 구성 종 수가 현저히 적었고 다양도지수 및 균등도가 낮았으며 그 다음은 자란도와 이수도순이었다. 우점도는 덕동이 가장 높았고 자란도, 이수도순이었다. 또한 조사지역 내에서 연체류중 패각만 채집된 종수가 덕동에서 19종, 자란도 3종, 이수도 4종으로 중복된 것을 제외하면 총 25종이 되며 이들 또한 오염과 관계 있을 것으로 예견된다.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.684-693
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• 2017

The purpose of this study was to analyze fish communities in the Wonju stream located in Wonju-si in Gangwon-do, and to evaluate the health of the stream through past and present changes. We performed investigations four times from May 2015 to September 2016. In the survey, 5,201 individuals which belonged to 27 species and 9 families were collected. Zacco platypus was the dominant species and Pungtungia herziwas the subdominant species. Eight Korean endemic species (Acanthorhodeus gracilis, Zacco koreanus, Coreoleuciscus splendidus, Squalidus gracilis majimae, Microphysogobio yaluensis, Iksookimia koreensis, Koreocobitis rotundicaudata, Coreoperca herzi) were observed and showed a ratio of 16.54%. The fish community of dominance ($0.72{\pm}0.10$), diversity ($1.37{\pm}0.32$), evenness ($0.61{\pm}0.13$), and richness ($1.70{\pm}0.23$) were evaluated. According to our analysis of tolerance guilds, the total individual number of intermediate species was higher than the sensitive and tolerant species. As a result of the trophic guild analysis,the omnivore and insectivore species were relatively high. The value of the qualitative habitat evaluation index (QHEI) in the wonju stream was averaged 121.2 (${\pm}23.4$), indicating a suboptimal condition. Stream health showed that the fish assessment index (FAI) value was an A to C grade in the Wonju stream. A correlation coefficient analysis with FAI and various factors was analysed statistically, and had a high correlation in QHEI, with the omnivore species, insectivore species, intermediate species, sensitive species, dominance, diversity, evenness, and richness.

• Korean Journal of Ecology and Environment
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• v.54 no.2
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• pp.108-119
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• 2021

We aimed to develop a naturalness index for forest-dwelling birds in four national parks in Korea and to simulate the effect of species loss on this naturalness index. Five bird specialists were asked to give 112 bird species a disturbance susceptibility score (DSS), and the naturalness index was calculated based on this. The 112 bird species represented 8 orders (Cuculiformes, Piciformes, Accipitriformes, Falconiformes, Columbiformes, Caprimulgiformes, Strigiformes, and Passeriformes). DSS was the highest for Terpsiphone atrocaudata and Pitta nympha, and lowest for Pica pica, Hypsipetes amaurotis, and Streptopelia orientalis. There was a significant negative relationship between a species' population number and its DSS. Among the four national parks, Mt. Songni had the highest naturalness index, followed by Mt. Wolak, Mt. Juwang, and Mt. Wolchul. We investigated the change in biodiversity indices under four scenarios, which assumed the extinction of species with less than 5 (Scenario 1), 10 (Scenario 2), 50 (Scenario 3), and 100 individuals (Scenario 4). The results showed that although all biodiversity indices decreased as the species loss increased, they all behaved differently. Fisher's alpha diversity decreased as the number of species proportionally decreased. There was almost no change in Shannon-Wiener H' index in Scenarios 1 and 2. The naturalness index showed increased sensitivity in Scenarios 1 and 4. Our future aims are to obtain the DSS for all forest-dwelling bird species, and to adopt the naturalness index to evaluate temporal and spatial changes in biodiversity.

• Korean Journal of Environmental Biology
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• v.37 no.4
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• pp.652-663
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• 2019

The purpose of this study was to conduct ecological health assessments by using the fish communities in the Manchurian trout habitat. Sampling was conducted twice in July and September 2018. In the survey, 1,119 individuals belonging to 16 species and seven families were collected. The dominant species by number was Rhynchocypris kumgangensis and the subdominant species was Zacco koreanus. Korean endemic species represented 73.33% at Geybang Stream and 76.92% at Naerin Stream. Community analysis revealed that the structure of the fish community was unstable by the dominance index 0.63 (±0.09)-0.97 (±0.01), the diversity index 1.63 (±0.23)-0.33 (±0.09), the evenness index 0.79 (±0.06)-0.24 (±0.07) and the richness index 0.67 (±0.14)-1.80(±0.16). According to the analysis of the tolerance guilds, the total individual number of sensitive species was higher than the intermediate and tolerant species. The insectivore species accounted for 65.09-98.56% of the total trophic guilds, which was the highest observed. The value of the QHEI (Qualitative habitat evaluation index) in the Brachymystax lenok tsinlingensis habitat was 119.5 (±0.5)-153.5 (±0.5), indicating an optimal-suboptimal condition. The FAI (Fish assessment index) stream health value was A to B in the study sites. Correlation analysis with FAI and various factors was conducted and a high correlation in QHEI, Brachymystax lenok tsinlingensis individuals, species, individuals, diversity, richness, sensitive species, carnivorous species, insectivorous species, and omnivorous species was found. The similarity analysis was divided into three groups from A to C, based on 56.9%.

• The Korean Journal of Applied Statistics
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• v.34 no.5
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• pp.711-721
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• 2021

In this paper, we propose the method of adjusting thresholds using impurity indices in classification analysis on imbalanced data. Suppose the minority category is Positive and the majority category is Negative for the imbalanced binomial data. When categories are determined based on the commonly used 0.5 basis, the specificity tends to be high in unbalanced data while the sensitivity is relatively low. Increasing sensitivity is important when proper classification of objects in minority categories is relatively important. We explore how to increase sensitivity through adjusting thresholds. Existing studies have adjusted thresholds based on measures such as G-Mean and F1-score, but in this paper, we propose a method to select optimal thresholds using the chi-square statistic of CHAID, the Gini index of CART, and the entropy of C4.5. We also introduce how to get a possible unique value when multiple optimal thresholds are obtained. Empirical analysis shows what improvements have been made compared to the results based on 0.5 through classification performance metrics.