• Ocean and Polar Research
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• 제43권4호
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• pp.353-363
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• 2021

Fluorescent dissolved organic matter (FDOM) is referred to organic matter which absorbs efficiently solar radiation energy and fluorescence in the water column. The component and molecular structure of marine organic matter can be changed depending on the various substances and origins of organic matter, and then the organic matter has unique fluorescent properties. As the cutting-edge analytical techniques of optical measurement continuously developing from last few decades, a study on FDOM has been applied as a biogeochemical tracer to quantify the organic matter concentration and to investigate the behaviors and origins of organic matter. Especially, the marine environment around the Korean Peninsula is an ideal research area to study FDOM because of various oceanographic characteristics and the origins of organic matter. This study describes the general properties of FDOM and introduces the cycling and behaviors of marine organic matter based on the domestic research studies.

• 전자공학회논문지 IE
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• 제43권4호
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• pp.21-27
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• 2006

본 논문은 사람의 뇌에 대한 자기공명영상에서 백질과 회백질을 분리하고 각각의 체적을 산출하기 위한 것이다. 정상인과 비정상인의 대뇌 영상으로부터 백질, 회백질, 뇌척수액을 분리하고, 분리된 조직의 체적을 계산한다. 본 논문에서는 뇌 MR영상에서 체적을 산출하고 백질과 회백질을 산출하기 위한 새로운 방법을 제안한다. 그리고 각 구성 비율에 따라 표현되는 명암 값 분석을 통한 대뇌 자기공명영상으로부터 백질 및 회백질을 추출할 수 있는 판별값을 결정하는 방법을 개발하였다. 각 슬라이스에 추출된 화소의 수를 이용하여 백질 및 회백질의 체적을 구하는 방법을 제안하였다. 그리고 환자의 뇌척수액/대뇌 체적비와 연령을 입력으로 받아 판별식을 통해 판별값을 계산하며, 계산된 판별값을 이용해 기준점과 비교함으로써 정상과 비정상을 진단하였다. 결과적으로 연령이 증가 할수록 백질과 회백질의 체적은 감소하고 뇌척수액의 체적은 증가하고 있는 것을 알 수 있었다.

• 천문학논총
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• 제7권1호
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• pp.31-37
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• 1992

Dark matter in various size of scales is reviewed briefly. The evidence of dark matter in dwarf spheroidal galaxies is still uncertain. However there is no doubt about the existence of dark matter in larger scales. Many proposed candidates for dark matter are still speculative. Several possibilities of direct detection of dark matter are proposed.

• 아시안잔디학회지
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• 제4권1호
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• pp.24-30
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• 1990

This study was carried out to search for growth and quality -of turfgrass by Nitrogen source (Urea Ammonium sulphate) and organic matter, and to obtain methods of pr6per turfgrass management by the results. This experiment was conducted in turf field from 1988 to 1989. The results of this experiment was summarized as follows; 1.Without application of organic matter, turfgrass growth between urea and ammonium sulphate was not significant, however ammonium sulphate resulted in superior to urea in total dry weight when organic matter was applied. 2.The addition of organic matter showed significant effect on color rating and visible quality, and ammonium sulphate was higher quality than urea. 3.Shoot density increased, particularly in ammonium sulphate treatment, when organic matter was applied. 4.Rhizome and stolon were shown significant effect in urea treatment by the application of organic matter. 5.Surface soil pH was allowed to become slightly acid by the ammonium sulphate treatments, but soil acidity remained mostly unaffected when organic matter was supplied. 6.Total nitrogen of log tissue and organic matter content increased when organic matter w-as applied.

• 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.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2008년도 High Temperature Superconductivity Vol.XVIII
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• pp.2-2
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• 2008

• 한국환경농학회지
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• 제20권5호
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• pp.346-351
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• 2001

Oxidation of Cr(III) to Cr(VI) can increase availability and toxicity of chromium. In this study, possible mechanisms by which pH and organic matter can control the chromium oxidation and reduction in soil system were examined using four soils of different pHs and organic matter contents. Reduction of Mn-oxides occurred in the soils of higher organic matter content (4.0%), but Mn-oxide was quite stable during the incubation in the soil of pH 7.0 and 0.5% organic matter content. Manganese oxides can be reductively dissolved at lower pH and higher organic matter conditions. The soil of pH 7.0 and 4.0% organic matter content showed the highest Cr-oxidation potential. Reduction of soluble Cr(VI) was observed in all the soils examined. The most rapid reduction was found in soil of pH 5.5 and 4.0% organic matter content, but the reduction was slow in soil of pH 7.0 and 0.5% organic matter content. Thus, the reductive capacity of organic matter added soils was much higher as compared to other two soils of lower organic matter content. In all the soils examined, the reductive capacity of soluble chromium was much higher than the oxidative capacity. Organic matter was found to be the most important controlling factor in the chromium oxidation and reduction. Reduction of Cr(VI) to Cr(III) could be a potentially useful remediation or detoxification process, and availability and toxicity of chromium in soil would be controlled by controlling organic matter content and pH of the soils.

• 한국초등과학교육학회지:초등과학교육
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• 제41권1호
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• pp.150-161
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• 2022

물질은 대표적인 과학의 기본 개념이지만 추상성으로 인해 학생들이 이해하는 데 어려움을 겪는 개념 중 하나이다. 본 연구에서는 초등학생들의 물질에 대한 개념과 물질 및 물질이 아닌 것의 예에 대한 이해를 학년에 걸쳐 조사하고 비교하여 그 특징을 살펴보았다. 연구 대상은 3학년부터 6학년 학생 총 418명이었으며, 자유응답식 설문을 통하여 자료를 수집하였다. 연구 결과 첫째, 물질에 대한 초등학생들의 주요 개념은 '물체를 이루는 재료', '보고 만질 수 있는 것', '고체, 액체, 기체에 해당하는 것'이었다. 학년이 올라감에 따라 재료 관점의 설명 비율은 줄어들고, 상태 관점의 설명 비율이 높아지는 경향이 있었으며, 물질을 무게와 부피를 가진 것으로 설명하는 학생은 거의 없었다. 둘째, 학생들이 제시한 물질의 예는 대부분 고체였으며, 고학년으로 갈수록 액체와 기체 상태의 예도 늘어났다. 그러나 오히려 고학년에서 물체와 물질을 구분하지 않는 경우들이 늘어나는 특징이 있었다. 셋째, 물질이 아닌 것의 예로 물체, 액체, 기체가 언급되는 가운데 다른 학년에 비해서 6학년 학생들은 물질이 아닌 것의 예를 더 잘 제시하였다. 마지막으로, 학생들의 물질에 대한 개념은 그들이 제시하는 물질 및 비물질의 예에 영향을 미침을 알 수 있었다.

• Membrane and Water Treatment
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• 제13권1호
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• pp.29-37
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• 2022

To verify the fate and transport of engineered nanoparticles (ENP), it is essential to understand its interactions with organic matter. Previous research has shown that dissolved organic matter (DOM) can increase particle stability through steric repulsion. However, the majority of the research has been focused on model organic matter such as humic or fulvic acids, lacking the understanding of organic matter found in field conditions. In the current study, organic matter was sampled from wastewater treatment plants to verify the stability of engineered nanoparticles (ENP) under field conditions. To understand how different types of organic matter may affect the fate of ENP, wastewater was sampled and separated based on their size; as small organic particular matter (SOPM) and large organic particular matter (LOPM), and dissolved organic matter (DOM). Each size fraction of organic matter was tested to verify their effects on nano-zinc oxide (nZnO) and nano-titanium oxide (nTiO₂) stability. For DOM, critical coagulation concentration (CCC) experiments were conducted, while sorption experiments were conducted for organic particulates. Results showed that under field conditions, the surface charge of the particles did not influence the stability. On the contrary, surface charge of the particles influenced the amount of sorption onto particulate forms of organic matter. Results of the current research show how the size of organic matter influences the fate and transport of different ENPs under field conditions.

• 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.