• Journal of Information Processing Systems
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• 제2권1호
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• pp.23-27
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• 2006

This paper presents a feature selection technique based on distributional differences for efficient machine learning. Initial training data consists of data including many features and a target value. We classified them into positive and negative data based on the target value. We then divided the range of the feature values into 10 intervals and calculated the distribution of the intervals in each positive and negative data. Then, we selected the features and the intervals of the features for which the distributional differences are over a certain threshold. Using the selected intervals and features, we could obtain the reduced training data. In the experiments, we will show that the reduced training data can reduce the training time of the neural network by about 40%, and we can obtain more profit on simulated stock trading using the trained functions as well.

• Journal of Species Research
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• 제8권4호
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• pp.365-372
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• 2019

We have conducted faunistic study of sea lice collected from marine plankton samples of western and southern coasts of Korea. These specimens were identified as Caligus undulatus Shen and Li, 1959, belonging to family Caligidae and order Siphonostomatoida with worldwide distribution. The range extension of C. undulatus is reported in addition to the previously known distributional range from the Northwest Pacific (China, Japan, and Korea), India, Brazil, and Mexico. This species can be distinguished from all previous reports with characteristics such as overall body proportions of both sexes, structure details of mouth appendages, armature of legs, and some variation in body size. The distributional range of C. undulatus is now given with its northern and south hemisphere limit being 40 to $10^{\circ}N$ in the Indo-Pacific and $30^{\circ}S$ in the Southwest Atlantic. This is the first record of its female occurring in Korea.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1990년도 춘계공동학술대회논문집; 한국과학기술원; 28 Apr. 1990
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• pp.272-288
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• 1990

The uncertainty quantification process in probabilistic Risk Assessment usually involves a specification of the uncertainty in the input data and the propagation of this uncertainty to the final risk results. The distributional sensitivity analysis is to study the impact of the various assumptions made during the quantification of input parameter uncertainties on the final output uncertainty. The uncertainty importance of input parameters, in this case, should reflect the degree of changes in the whole output distribution and not just in a point estimate value. A measure of the uncertainty importance is proposed in the present paper. The measure is called the distributional sensitivity measure(DSM) and explicitly derived from the definition of the Kullback's discrimination information. The DSM is applied to three typical discrimination information. The DSM is applied to three typical cases of input distributional changes: 1) Uncertainty is completely eliminated, 2) Uncertainty range is increased by a factor of 10, and 3) Type of distribution is changed. For all three cases of application, the DSM-based importance ranking agrees very well with the observed changes of output distribution while other statistical parameters are shown to be insensitive.

• 한국동물학회지
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• 제36권2호
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• pp.175-180
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• 1993

Eighty one specimens of nhodeus sericeus (Pallas, 1176) were collected at the upper stream of the Som River (37$^{\circ}$32' 38" N, 127$^{\circ}$58' 57" E: Maegok-ri, Konggun-myon, Hoengsong-gun, Kanguvon-do, Korea) which is a tributary of the Namhan River. This is the first report of the species in the southern part of the Korean Peninsula. This species is well discriminated from the other species in the genus nhodeus by the following respects. The number of scales of transverse series is more than 34 (range 34-37, mean 35.7 $\pm$0.7). Head is echo감or and snout is Bonder than those of the other species. The upper part of the eve is always black and the lateral body surfaces are reddish purple. It had been hem that the southern limit of the distribution of Rhodeus sericeus was the Yonghung River in Hamgvongnam-do, north-eastern part of the Korean Peninsula. But their distributional range is extended more southerly to the Han River system which tons westward through the central part of the Korean Peninsula.Peninsula.

• The Korean Journal of Ecology
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• 제8권2호
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• pp.89-98
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• 1985

Correlations between horizontal distributions of bamboos (Bambusaceae) in the Korean peninsula and environmental factors were studied using taxanomic and geographical literatures, both old and current. The vertical distributions of bamboos on Mt. Chiri were also studied, and environmental factors limiting horizontal and vertical distributions were compared. There are 18 species of bamboos (belonging to 5 genera) distributed in the Korean peninsula. The distributional range of each genus were distinct, although overlapped. Northern limit of bamboos of any species was marked by the line connecting Paikryung Island (124。40'E, 38。00'N), Mt. Changsoo, Mt. Myungji, Mt. Myohyung and Myungchum (129。40'E, 41。10'N). The optimum range of bamboos was concluded to be restricted to several southern province, with annual precipitation over 1,200 mm. The limiting factors on the distribution were inferred to be low temperature and duration of it. Mean daily minimum temperature of January and the number of days with daily mean temperatures below zero during January showed close associations with the distributional range, and an environmental factors favouring the distributrion of bamboos appeared to be vicinity of warm sea current, deep and extended snow acculation and southern exposure. The vertical distribution of bamboos on Mt. Chiri was limited by low temperature, unfavorable topographic and edaphic conditions caused by steep slope. Difference in the vertical limits between SE and NW slopes are caused by the differences in temperature and precipitation between the slopes. Bamboos were more abundant in valleys than on the ridge, apparently because the deeper snow in the valleys protected the plants from low temperature, heavy winter winds and desiccation.

• Journal of Ecology and Environment
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• 제45권3호
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• pp.130-142
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• 2021

Background: Climate change is occurring rapidly around the world, and is predicted to have a large impact on biodiversity. Various studies have shown that climate change can alter the geographical distribution of wild bees. As climate change affects the species distribution and causes range shift, the degree of range shift and the quality of the habitats are becoming more important for securing the species diversity. In addition, those pollinator insects are contributing not only to shaping the natural ecosystem but also to increased crop production. The distributional and habitat quality changes of wild bees are of utmost importance in the climate change era. This study aims to investigate the impact of climate change on distributional and habitat quality changes of five wild bees in northwestern regions of Iran under two representative concentration pathway scenarios (RCP 4.5 and RCP 8.5). We used species distribution models to predict the potential range shift of these species in the year 2070. Result: The effects of climate change on different species are different, and the increase in temperature mainly expands the distribution ranges of wild bees, except for one species that is estimated to have a reduced potential range. Therefore, the increase in temperature would force wild bees to shift to higher latitudes. There was also significant uncertainty in the use of different models and the number of environmental layers employed in the modeling of habitat suitability. Conclusion: The increase in temperature caused the expansion of species distribution and wider areas would be available to the studied species in the future. However, not all of this possible range may include high-quality habitats, and wild bees may limit their niche to suitable habitats. On the other hand, the movement of species to higher latitudes will cause a mismatch between farms and suitable areas for wild bees, and as a result, farmers will face a shortage of pollination from wild bees. We suggest that farmers in these areas be aware of the effects of climate change on agricultural production and consider the use of managed bees in the future.

• 한국지형학회지
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• 제25권4호
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• pp.1-19
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• 2018

This study tries to identify distributional characteristics of stream incision rates at 23 points in the northern part of the Taebaek Mountains. Soyang-gang, Naerin-cheon, Odae-cheon, Dong-gang and upper reaches of Okdong-cheon Rivers closed to the Range show higher incision rates and the rates clearly decrease with distance from the Range. Therefore, the incision process in the northern part of the Range has been greatly influenced by uplift around the Range, and the Sobaek Mountain Range seem to play a role in the incision process. Limestone areas show lower incision rates due to degradation of terrace surface by dissolution. This study suggests that local hydrological, geological and geomorphological conditions can be regarded as an important factor in stream incision rates, although stream incision rates are greatly influenced by regional uplift.

• 대한지리학회지
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• 제36권3호
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• pp.247-257
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• 2001

한반도에 자생하는 상록활엽수의 종류에 따는 지리적 분포와 기후요소와의 관계를 분석하였다. 우리나라 의 61속 132종 상록활엽수 분포하는 지역의 수 수직적 고도 범위, 위도에 따라 7개의 그룹으로 분류되었다. 7개의 그룹은 다시 분포의 남한한계선을 갖는 한대성 상록활엽수와 북방한계선을 갖는 난대성 상롭활엽수로 나뉘었다. 한대성 상록활엽수와 난대성 상롭활엽수의 분포와 관련되는 기후요소늘 연평균기온(Ty). 1월 평균기온(T1). 1월 평균최저기온(Tmin1) 8월 평균기온(T8), 8월 평균최고기온(Tmax 8), 연교차(Tar) 등이며. 종류에 따라 분포에 영향을 미치는 기후요소는 달랐다. 난태성 상록활엽수의 분포에 중요한 것은 주로 1월 평균기온 -4$^{\circ}C$, 1월 평균최저기온 -9$^{\circ}C$이다. 한대성 상롭활엽수의 분포는 8월 평균기온 19$^{\circ}C$, 8월 평균최고기온 26$^{\circ}C$가 다른 기온조건보다 중요한것으로 판단된다..

• The Korean Journal of Ecology
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• 제6권3호
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• pp.153-166
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• 1983

The distribution of beech species (Fagus) and beech-dominated forests along climatic gradients in the Northern Hemisphere was studied by use of taxonomic and ecological literature. The genus Fagus as a whole occurs over the range of 4.5 to 20.0。C mean annual temperature and 600 to 1000 mm in lower limit, mean annual precipitation. At the higher end of the temperature range, beech occurs in zones with relatively high growing-season precipitation. Edaphically, beech species and beech-dominated forests tend to occur on mesic, moderately fertile sites. Beech-dominated forests occur in a limited portion of the climatic range of the genus with sensitive responses to other environmental factors. The distributional range of beech-dominated forests on a global scale depends more on climatic factors and geological events than on soil conditions or other factors, summarizing the facts obtained by many researchers on beech dominated forests.

• 한국동물학회지
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• 제15권2호
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• pp.87-91
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• 1972

西部 北太平洋에 있어서의 本種에 대한 地理分布와 垂直分布 및 晝夜垂直移動에 관한 知見은 극히 限定된 海域과 深度에 있어서의 報告가 있을 뿐이다. 筆者는 北緯 20度에서 47度에 이르는 東經 50度 以西의 西部 北太平洋과 이의 附屬海에 걸친 광범위한 調査를 통하여 本種의 地理分布에 관한 새로운 知見을 얻었다. 그 結果로 東支那海의 表層을 제외한 68地點에서 本種이 出現함으로써 浮游性 端脚類中에서도 唯一하게 西部 北太平洋 全域에 걸쳐 一樣하게 分布하고 있으며 季節的인 消長이 없음이 究明되었다. 한편 垂直的으로는 0 $\\sim$ 1,500m 以上에 分布하고 있으며 最深採集記錄은 定點 229 $(34^\\circ 44.3'N, 140^\\circ 04.4'E)$에서의 1,650 $\\sim$ 2,220m層에서 얻어졌다. 晝夜垂直移動의 類型을 보면 本種은 晝間에는 深層部에 分布하며 夜間에 表層部로 현저한 晝夜移動을 하고 있음을 밝혔다. 이 移動의 範圍는 100 $\\sim$ 200m에 달한다. 또한 黑潮域에서는 新潮域에 비하여 垂直分布의 深度가 얕으며 서로 垂直分布의 深度와 移動의 範圍가 다르다. 즉 黑潮域에서는 晝間 0 $\\sim$ 200m層에 夜間 100 $\\sim$ 300m層에 個體群의 中心이 分布하며 100m의 範圍로 垂直移動을 하는데 反하여 新潮域에서는 晝間 400 $\\sim$ 700m, 夜間 100 $\\sim$ 500m로 200m의 範圍로 移動한다. 이는 兩海域에 있어서의 個體群의 組成이 서로 다른데 起因되는 결과로 사료된다.