• Annals of Clinical Neurophysiology
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• 제4권1호
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• pp.21-27
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• 2002

Background : Spatial analysis of EEG is a phenomenal assessment and not so informative for phase space and dynamic aspect of EEG data. In contrast, nonlinear EEG analysis attempts to characterize the dynamics of neural networks in the brain. We have analyzed the features of EEG nonlinearly in subjects with white matter change on brain MRI and compared the results with cognitive function in each. Methods : Digital EEG data were taken for 30 seconds in 9 subjects with white matter degeneration and in 5 healthy normal controls without white matter change on MRI. Then we analyzed them nonlinearly to calculate the correlation dimension(D2) using the MATLAB software. The cognitive function was assessed by 3MS(modified mini-mental state examination). The severity of white matter change was assessed by Scheltens scale. Results : The mean D2 value of normal control was greater than that of white matter degeneration group. The D2s of some channels were correlative with 3MS and degree of white matter degeneration significantly. Conclusions : nonlinear analysis of EEG can be used as one of adjuvant functional studies for prediction of cognitive impairment in subjects with white matter degeneration and subcortical white matter change can be influential on cognitive function and correlation dimension of EEG.

• 대한화학회지
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• 제66권6호
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• pp.493-508
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• 2022

화학은 물질의 성질, 변화, 구조에 대해 다루는 교과로, 관찰 가능한 성질과 변화를 미시적인 수준으로 설명하고, 이를 이론과 법칙 등으로 설명하는 체계를 갖는다. 국가수준 교육과정에서는 물질의 성질과 변화에 대해 초등학교부터 고등학교에 이르기까지 연속적으로 다루면서, 학생들이 물질에 대한 이해를 심화시킬 수 있도록 내용을 구성하고 있다. 즉, 물질의 성질과 변화에 대한 이해는 화학의 관점에서 우리 주변을 설명하기 위한 기반이 되며, 이 둘은 2015 개정 과학과 교육과정에서 화학 교과의 영역으로 분류된다. 본 연구에서는 국가수준 학업성취도 평가의 결과를 분석하여 중학생들의 물질의 성질과 물질의 변화 영역에 대한 이해를 확인하고자 하였다. 이러한 목적에서 본 연구에서는 2015년부터 2019년까지 출제된 물질의 성질에 대한 12개 문항, 물질의 변화에 대한 19개 문항을 분석하였다. 핵심 개념에 따라 문항들을 분류하여 분석한 결과에 따르면, 두 영역에 대한 이해는 보통학력과 기초학력에 해당하는 학생들에게서 큰 폭으로 변화하고 있었다. 입자의 관점을 사용하고 과학 개념과 모형을 연관시켜 현상을 설명하거나, 이 두 영역에서 다루는 탐구에 대해 이해하는 것이 성취수준에 따라 차이가 있었다. 이러한 분석을 토대로 물질의 성질과 물질의 변화 영역에 대해 교수학습 과정에서 개선이 필요한 사항들을 논의하였다.

• 한국초등과학교육학회지:초등과학교육
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• 제19권1호
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• pp.113-129
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• 2000

The purposes of this study were to investigate children's preconception about matter, to analyze children's conceptual change. of ,matter by science learning activities, and to investigate understanding possibility about mallet The subjects of this study were the second grade students of an elementary school and science learning activities were conducted to 2 boys and 3 girls for investigating their conceptual change. Video tape recording, interview, drawing pictures and writing statements were used to collect data. The concepts in this study were properties of matter, states of matter, uses of matter and origins and changes in matter. Then, the collected data were analyzed by the way of categorization and qualitative method. The conclusions of this study are as follows: science loaming activities were effective for changing misconceptions of matter to scientific concepts. Conceptual changes of high achievers happened easier and more than of low achievers. In the ideas about matter, some children had supernatural ideas and animism, which were most second grade students' characteristics.

• 대한화학회지
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• 제48권1호
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• pp.53-65
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• 2004

이 연구에서는 물질의 성질을 나타내는 기본 단위 중 분자에 대한 개념과 물리변화와 화학변화로 대변되는 물질변화 개념의 변천을 과학사적으로 고찰하여 특징적인 관점의 변화에 따라 구분하였다. 이 연구에서는 물질의 성질을 나타내는 기본 단위를 과학사적 변천에 따라 5가지 관점으로 유목화하였다. 그리고 물리변화와 화학변화의 정의는 물질의 성질을 나타내는 기본 단위의 개념과 밀접한 관련성을 가지는 3가지 관점으로 유목화하였다. 중학교 과학 교과서와 고등학교 화학 교과서, 그리고 대학교 일반화학 교과서에 제시된 개념을 분석한 결과, 분자의 정의와 물질 변화의 정의 안에는 이러한 여러 시대의 정의들이 혼재된 상태로 제시되어 있음을 확인할 수 있었다. 경우에 따라서는 진술 자체에 논리적 모순점이 있는 경우도 있었다. 이러한 경향은 제 4차 과학 교육과정에서부터 제 7차 과학 교육과정까지의 과학 교과서에서 지속되었다.

• 한국물환경학회지
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• 제34권5호
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• pp.487-493
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• 2018

Urban stormwater runoff is the one of the most extensive causes of deterioration of water quality in streams in urban areas. Especially, in the Suyeong River watershed, non-point sources from urban-residential areas are the most common cause of water pollution. Also, it has been ascertained that BOD and COD as indexes of organic matter, have limitation on management of Suyeong River's water quality. In this study, changes of organic matter properties of Suyeong River from inflow of non-point source during rainfall were investigated. Fractions of organic matters were analyzed using water samples collected at two sites (Suyeong River and Oncheon Stream) during a rain event. Variations of dissolved organic carbon (DOC) concentration by rainfall were similar to flow rate change in the river. Distribution of organic matter fraction according to change of rain duration revealed that while hydrophilic component increased at initial rainfall, the hydrophobic component was similar to change in dissolved organic carbon (DOC) concentration. Also, the relative proportion of hydrophilic components in organic matter in river water increased, due to rainfall. Results of biodegradation of organic matters revealed that decomposition rate of organic matters during rainfall was higher than that of during a non-rainfall event.

• 한국물환경학회지
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• 제27권1호
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• pp.88-97
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• 2011

To identify the inflow and outflow characteristics of allchthonous organic matters and examine the change of allochthonous organic matter load pattern due to the climate change, we investigated the temporal variations of DOC and POC concentrations within inflow water and dam discharge water and spatio-temporal distribution of POM within the lake water in Lake Soyang which is the largest dam reservoir in Korea in 2006. Most of allochthonous DOC flowed into the lake water during initial rain and was not affected by the amount of precipitation, whereas most of allochthonous POC flowed into during concentrated heavy rain and the concentration of POC was significantly associated with the amount of inflow water and precipitation. Calculated annual allochthonous organic matter loads in Lake Soyang from 2003 to 2006 using the regression equation between the amount of inflow water and the concentration of POC indicate allochthonous organic matter loads are mainly affected by total influx and extreme influx of inflow water. The spatio-temporal distribution of POM indicated allochthonous organic matter of inflow river during flood period in July transported from upper part to middle and lower part of the lake a month later respectively along the middle layer of water column in Lake Soyang.

• Asian-Australasian Journal of Animal Sciences
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• 제16권9호
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• pp.1297-1302
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• 2003

To determine whether the feeding of different species of hay affects the dry-matter intake and the serum cortisol level of sheep, 6 non-pregnant, non-lactating ewes were offered alfalfa (Medicago sativa) hay (Al), oats (Avena sativa) hay (Ot) and perennial ryegrass (Lolium perenne) hay (Pr) under 6 kinds of treatment including 1) change from Al to Ot, 2) Al to Pr, 3) Ot to Al, 4) Ot to Pr, 5) Pr to Al, and 6) Pr to Ot. The experimental design was a 6${\times}$6 Latin square with a 14 day period of which 9 days were a preliminary period and 5 days as a digestion trial period. The change in hay feeding was done abruptly on the first day of each period without an adaptation period. The blood from the jugular vein was collected on the first, third and the last day of each period through a sterile catheter for the analysis of cortisol. The dry-matter intake was recorded daily throughout the period. The mean daily intake of dry matter (DM, g/kg live weight) was significantly different among the 3 species of hay (Al>Ot>Pr; p<0.05). The digestibility of DM for Al and Ot was the same, but that for Pr was significantly lower than Al and Ot (p<0.05). The mean serum cortisol levels were significantly different among the hays (p<0.05). The level for Pr was the highest and that for Al was the lowest. The abrupt change of hay feeding of 6 treatments produced a significant change in the serum cortisol levels. The DM intake was inversely related to the change of the cortisol level. It is suggested that the animal' intake response to different species of hay may be partly motivated by the psychological feelings toward the hay offered.

• Ocean and Polar Research
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• 제24권2호
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• pp.167-175
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• 2002

Sediment from six piston cores from the East Sea (Sea of Japan) was analyzed for evidence of paleoceanographic changes and paleoclimatic variation. A distinct geochemical boundary is evident in major element concentrations and organic carbon content of most cores near the 10-ka horizon. This distinctive basal Holocene change is interpreted to be largely the result of changing sediment sources, an interpretation supported by TiO_2/Al_2O_3$ ratios. Organic carbon and carbonate contents also differ significantly between the Holocene and glacial intervals. The C/N ratio of organic matter is greater than 10 during the glacial period, but is less than 10 for the Holocene, suggesting that the influx of terrigenous organic matter was more volumetrically important than marine organic matter during glacial times. The chemical index of weathering (CIW) is higher for the Holocene than the glacial interval, and changes markedly at the basal Holocene geochemical boundary. Silt fractions are higher in the glacial interval, suggesting a strong effect of climate on silt particle transportation: terrigenous aluminosilicates and continental organic carbon transport were higher during glacial times than during the Holocene. Differences in sediment composition between the Holocene and glacial period are interpreted to have been climatically induced.

• 한국초등과학교육학회지:초등과학교육
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• 제37권2호
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• pp.147-160
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• 2018

The purpose of this study is to compare the elementary science curriculum and textbooks of Korea, the United States, Japan, and Singapore to know how the contents on particulate concept of matter is introduced and expressed. In Korea, particulate concept of matter was adopted as a term for 'molecules' in the 3rd through 6th curriculum, and the term for 'particles' was adopted in the 2009 revised curriculum. In the United States, NGSS adopted the term 'particle' in fifth grade. Japan presented the concept of 'particle' as a core concept of matter in the commentary, and the expressions 'particles' were being introduced in the textbooks. But it did not cover particulate nature of matter at the elementary school level in Singapore. An analysis of elementary textbooks in Korea, the United States and Japan except Singapore showed particulate expressions in 'dissolution', 'state change of water', 'gas pressure and volume', 'combustion and extinguishment' units. Korean textbook was only being introduced in 'dissolution' and 'gas pressure and volume', but in the textbooks of Japan and the United States, water was expressed as particles in 'state change of water' unit. Discussion and implication on the introduction of particulate concept to elementary science curriculum and textbooks were suggested based on the results.

• Communications for Statistical Applications and Methods
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• 제26권6호
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• pp.539-556
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• 2019

This paper derive a method to solve change point regression problems via a process for obtaining consequential results using properties of a difference-based intercept estimator first introduced by Park and Kim (Communications in Statistics - Theory Methods, 2019) for outlier detection in multiple linear regression models. We describe the statistical properties of the difference-based regression model in a piecewise simple linear regression model and then propose an efficient algorithm for change point detection. We illustrate the merits of our proposed method in the light of comparison with several existing methods under simulation studies and real data analysis. This methodology is quite valuable, "no matter what regression lines" and "no matter what the number of change points".