• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.1 no.1
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• pp.1-8
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• 2020

Recent studies revealed that many animals identify individual humans. In this account, we review previous literatures on individual human recognition by wild or domestic animals and discuss the three hypotheses: "high cognitive abilities" hypothesis, "close human contact" and "pre-exposure to stimuli" hypothesis. The three hypotheses are not mutually exclusive. Close human contact hypothesis is an ultimate explanation for adaptive benefits whereas high cognitive abilities and pre-exposure to stimuli hypothesis are proximate explanations for mechanisms to perform such discriminatory behaviour. We report a case study of two bird species in a human-free habitat. Long-tailed skuas, which are known for having high cognitive abilities, exhibited the human discriminatory abilities whereas ruddy turnstones did not display such abilities toward approaching humans. This suggests that highly intelligent species may have this type of discriminatory ability so that they could learn to identify individual humans quickly by pre-exposure to stimuli, even in a human-free habitat. Here, we discuss that human recognition is more common in species with rapid learning ability and it could develop for a short period of time between an intelligent species and human.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.1
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• pp.32-41
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• 2021

South Korea presently harbors less than 800 long-tailed gorals (Naemorhedus caudatus), an endangered species. I report for the first time on the taxonomic status and genetic diversity of the Korean species using non-invasive fecal sampling based on mitochondrial cytochrome b gene sequence analyses. To determine the taxonomic status of this species, I reconstructed a consensus neighbor-joining tree and generated a minimum spanning network combining haplotype sequences obtained from feces with a new goral-specific primer set developed using known sequences of the Korean goral and related species (e.g., Russian goral, Chinese goral, Himalayan goral, Japanese serow, etc.). I also examined the genetic diversity of this species. The Korean goral showed only three different haplotypes. The phylogenetic tree and parsimony haplotype network revealed a single cluster of Korean and Russian gorals, separate from related species. Generally, the Korean goral has a relatively low genetic diversity compared with that of other ungulate species (e.g., moose and red deer). I preliminarily showcased the application of non-invasive fecal sampling to the study of genetic characteristics, including the taxonomic status and genetic diversity of gorals, based on mitochondrial DNA. More phylogenetic studies are necessary to ensure the conservation of goral populations throughout South Korea.

• Journal of the Korean Mathematical Society
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• v.59 no.6
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• pp.1185-1201
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• 2022

Feller introduced an unfair-fair-game in his famous book [3]. In this game, at each trial, player will win 2^k yuan with probability p_k = 1/2^kk(k + 1), k ∈ ℕ, and zero yuan with probability p₀ = 1 - Σ^∞_k=1 p_k. Because the expected gain is 1, player must pay one yuan as the entrance fee for each trial. Although this game seemed "fair", Feller [2] proved that when the total trial number n is large enough, player will loss n yuan with its probability approximate 1. So it's an "unfair" game. In this paper, we study in depth its convergence in probability, almost sure convergence and convergence in distribution. Furthermore, we try to take 2^k = m to reduce the values of random variables and their corresponding probabilities at the same time, thus a new probability model is introduced, which is called as the related model of Feller's unfair-fair-game. We find out that this new model follows a long-tailed distribution. We obtain its weak law of large numbers, strong law of large numbers and central limit theorem. These results show that their probability limit behaviours of these two models are quite different.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.541-543
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• 2022

In recent years, retinal disorders have become a serious health concern. Retinal disorders develop slowly and without obvious signs. To avoid vision deterioration, early detection and treatment are critical. Optical coherence tomography (OCT) is a non-invasive and non-contact medical imaging technique used to acquire informative and high-resolution image of retinal area and underlying layers. Disease signs are difficult to detect because OCT images have many areas which are not related to any disease. In this paper, we present a deep learning-based method to perform multi-label classification on a long-tailed OCT dataset. Our method first extracts the region of interest and then performs the classification task. We achieve 98% accuracy, 92% sensitivity, and 99% specificity on our private OCT dataset. Using the heatmap generated from trained convolutional neural network, our method is more robust and explainable than previous approaches because it focuses on areas that contain disease signs.

• Journal of Environmental Impact Assessment
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• v.22 no.6
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• pp.745-751
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• 2013

Environmental Specimen Banks (ESBs) have been established widely in the world since 1979 for monitoring long-term bio-accumulation of environmental pollutants. The ESBs perform the retrospective analysis of representative biological samples collected regularly and store them in cryogenic condition. In Korea, National Environmental Specimen Bank (NESB) was established in 2009. Since then, NESB had prepared the standard operating procedures (SOPs) for the seven kinds of specimens (Red Pine (Pinus densiflora), Common Carp (Cyprinus carpio), and etc.) for monitoring the effect of environmental pollution on the terrestrial ecosystem and river ecosystem. In 2012, NESB added Black-tailed Gull (Larus crassirostris)'s eggs to the list of the environmental specimen for monitoring marine environmental pollution. In this study, we sampled the eggs of the Black-tailed Gull on two islands (Baekryeongdo of the West Sea and Hongdo of the South Sea). Especially, we selected eggs which remained in the early stages of embryo development for certifying the consistent and stable monitoring for environmental pollutants in egg contents. However, it was not considered to classify an order of eggs per clutch in this study. It is known that the concentration variations of pollutants exist among eggs in one clutch. Therefore, it is needed to consider the positions of eggs in the laying sequences to meet the objective of bioaccumulation monitoring. We collected 30 eggs in each site but the amount may be insufficient to achieve storage target (over 2,000 g). Therefore, we need to consider an optimal sampling size.

• Communications for Statistical Applications and Methods
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• v.12 no.2
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• pp.413-423
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• 2005

Consider the problem of estimating the underlying regression function from a set of noisy data which is contaminated by a long tailed error distribution. There exist several robust smoothing techniques and these are turned out to be very useful to reduce the influence of outlying observations. However, no matter what kind of robust smoother we use, we should choose the smoothing parameter and relatively less attention has been made for the robust bandwidth selection method. In this paper, we adopt the idea of robust location parameter estimation technique and propose the robust cross validation score functions.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.169-185
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• 2017

Physicochemical properties of water quality were analyzed to understand the long-term variations in Lake Youngrang from 1998 to 2015. Nonparametric statistical methods were applied to deduct correlation among water quality parameters and water quality trend. In total observations(N=64), the Secchi depth (SD) transparency showed significant positive correlation with salinity (r=0.458) and highly significant negative correlation with chlorophyll-a (r= -0.649) for p<0.0001 in two-tailed test of Spearman's rank correlation. Significant negative correlations of SD were observed with chemical oxygen demand (COD), total phosphorus (TP) and total nitrogen (TN). These correlation patterns were very similar in rainy (N=25) and non-rainy (N=39) periods too. Chlorophyll-a (Chl-a) had significant correlation with COD. Sen's slope test was performed along with Mann-Kendall trend test (significance ${\alpha}=0.05$, two-tailed) to find water quality trend. Positive trends were observed for SD and salinity with Sen's slopes 0.012 and 0.385, respectively (p<0.0001). Negative significant trends were observed for total nitrogen (TN) and Chl-a with Sen's slopes -0.02 (p<0.0001) and -0.346 (p=0.0010), respectively. Temperature, COD and phosphorus components had no trends. Carlson's trophic state index (TSI) for SD, TP and Chl-a were obtained in the ranges of 46~80, 37~82 and 39~82, respectively. Trophic index values suggest that Lake Youngrang was mesoeutrophic to eutrophic and there could be possibility of anoxia during the summer and dominance of blue-green algae. Excess nutrient inputs from external and internal sources were the causes of eutrophication in this lake. The findings of this study would be helpful to recognize water quality variables to manage the water body.

• Korean Journal of Environment and Ecology
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• v.25 no.3
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• pp.302-306
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• 2011

Amur's long-tailed goral(Naemorhedus Caudatus) winter scats inhabitants of Wolaksan National Park were surveyed between 2006 and 2009. The scats included seeds of Hovenia dulcis and we confirmed germination of seed from the scats in the spring. 600 dulcis seeds goral scats were collected in the same location and period and 600 normal seeds were also observed in order to study the effect of goral on germination of dulcis. All of the seed(totally 1,200) were cultured in the same condition. As a result, germination rates of seeds from the goral scats and normal seeds were 32.5% and 0.8% respectively. So we confirmed that dulcis seeds in goral habitats germinate approximately 40 times more than without goral.

• Korean Journal of Environment and Ecology
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• v.29 no.2
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• pp.184-191
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• 2015

This study aimed to analyze characteristics of the seasonal habitat use of reintroduced Long-tailed Gorals (n=7) in Woraksan (mountain) National Park. We collected 10,721 goral coordinates in Woraksan (mountain) National Park via transmitters, and analyzed habitat use (e.g., aspect, distance from stream and road) from November 2006 to January 2013. Aspect use was southwest (22.6 %), and seasonal aspect use had a southwestern slope (in the spring, summer, and autumn). A northwestern aspect was detected in winter, but slope of $30^{\circ}{\sim}35^{\circ}$ (19.0 %) was used regardless of the season and mean elevation use was 500 m. Moreover, seasonal use was higher in the summer and lower in the winter and spring. The distance from the stream was mainly 50 m in 17.2 %, except in the winter (distance of 300 m), and it was within 50 m in the spring, summer, and autumn. The distance from the road was 100 m in 25.7 %, and seasonal use was within 100 m except for the winter. Thus, we examined significant differences in the habitat use of reintroduced gorals in Woraksan (mountain), and provide elementary data for habitat stabilization of Woraksan (mountain) National Park where goral restoration has advanced.

• International Journal of Industrial Entomology and Biomaterials
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• v.46 no.2
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• pp.41-54
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• 2023

The blue-tailed damselfly, Ischnura elegans Van der Linden, 1820 (Odonata: Coenagrionidae), is a climate-sensitive indicator species in South Korea. In this study, we sequenced the complete mitochondrial genome (mitogenome) of I. elegans collected from South Korea for subsequent population genetic analysis, particularly to trace population movements in response to climate change. The 15,963 base pair (bp)-long complete mitogenome of I. elegans has typical sets of genes including a major non-coding region (the A+T-rich region), and an arrangement identical to that observed in ancestral insect species. The ATP6, ND3 and ND1 genes have the TTG start codon, which, although rare, is the canonical start codon for animal mitochondrial tRNA. The A/T content was 71.4% in protein-coding genes, 72.1% in tRNAs, 72.9% in the whole genome, 74.7% in srRNA, 75.3% in lrRNA, and 83.8% in the A+T-rich region. The A+T-rich region is unusually long (1,196 bp) and contains two subunits (192 bp and 176-165 bp), each of which is tandemly triplicated and surrounded by non-repeat sequences. Comparison of the sequence divergence among available mitogenomes of I. elegans, including the one from the current study, revealed ND2 as the most variable gene, followed by COII and COI, suggesting that ND2 should be targeted first in subsequent population-level studies. Phylogenetic reconstruction based on all available mitogenome sequences of Coenagrionidae showed a strong sister relationship between I. elegans and I. senegalensis.