• Journal of the Korean School Mathematics Society
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• v.19 no.1
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• pp.63-82
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• 2016

Mathematical notation is the main means to realize the power of mathematics. Under this perspective, this study analyzed the difficulties of learning an irrational number concept in terms of notation. I tried to find ways to overcome the difficulties arising from the notation. There are two primary ideas in the notation of irrational number using root. The first is that an irrational number should be represented by letter because it can not be expressed by decimal or fraction. The second is that $\sqrt{2}$ is a notation added the number in order to highlight the features that it can be 2 when it is squared. However it is difficult for learner to notice the reasons for using the root because the textbook does not provide the opportunity to discover. Furthermore, the reduction of the transparency for the letter in the development of history is more difficult to access from the conceptual aspects. Thus 'epistemological obstacles resulting from the double context' and 'epistemological obstacles originated by strengthening the transparency of the number' is expected. To overcome such epistemological obstacles, it is necessary to premise 'providing opportunities for development of notation' and 'an experience using the notation enhanced the transparency of the letter that the existing'. Based on these principles, this study proposed a plan consisting of six steps.

• The Journal of Korean Association of Computer Education
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• v.14 no.3
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• pp.13-23
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• 2011

Information Culture Index (ICI) is the quantitative value that represents people's information literacy levels. Also, it diagnoses the people's knowledge, ethics, emotion, and practice synthetically. As the Internet and cell phone addiction have been increasing when people access information on the web recently, it is necessary to analyze the meaning of the ICI from the Internet and cell phone addiction perspectives and to confirm if it goes well in the right direction. In this paper, we analyze the characteristics of the people who have high ICIs. At the same time, we perform the statistical analysis combining ICIs with the Internet and the cell-phone addiction levels. In particular, the meaning of the Information Practicing factor, which is one of the ICI factors, is examined. By doing these, we confirm if the current ICI works correctly or not, and propose a better way for measuring ICIs. In order to do these, we survey and analyze data with basic statistical methods and structural equation model.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.54-62
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• 2010

The scientific analysis of car-pedestrian accidents is not an easy task because of the characteristic of the accidents itself. Since the analysis involved human being, there were few experimental data that could be used for the analysis. The coefficient of friction of human body was the one of crucial data for accident analysis, but no field experiment report was available for various roadway conditions. This study intends to measure the coefficient of friction of human body through field studies. Results showed that the coefficient of friction of human body for dry asphalt pavement conditions was 0.59~0.62, and for dry concrete pavement conditions was 0.59~0.61. In addition, the coefficients for wet asphalt pavement and for wet concrete pavement conditions were 0.56~0.59 and 0.51~0.54 respectively, indicating 5.0% and 8.3% reduction compared to the dry conditions. The deduced coefficients were validated using the simulation program. It has been confirmed that the experiment values were close to the simulation results.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.271-271
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• 2011

최근의 유출해석은 지리정보체계(GIS, Geographic Information System) 및 지형자료(DEM, Digital Elevation Model 등) 구축의 발달로 대부분 격자 기반의 분포형 강우-유출 모형을 통해 이루어지고 있으며, Rodriguez-Iturbe and Valdes (1979)에 의해 소개된 통계물리학적 접근방법인 지형학적 순간단위도(GIUH)모형 역시 DEM을 기반으로 한 연구가 꾸준히 진행되어 온 실정이다(Maidment, 1993; D'odorico and Rigon, 2003; Di Lazzaro, 2010). 이러한 격자 기반 모형들은 대부분 8방향 최급경사에 기초한 흐름방향도를 기반으로 물의 유동을 표현한다. 8방향법에 의해 결정된 흐름방향도를 이용할 경우 각 격자 중심에서 유역출구 까지의 배수로경로길이를 비교적 쉽고, 빠르게 계산할 수 있다는 장점을 가지나, 공간해상도(격자 규모)에 따라 상이한 결과를 나타내는 것을 예상할 수 있다. 따라서 본 연구에서는 DEM의 공간해상도에 따른 배수경로길이의 통계적 변화양상을 살펴보고, 이로부터 실제 수문사상의 통계적 특성과 Di Lazzaro(2010)의 특성유속산정 공식을 이용해 지표면과 하천의 특성유속을 산정하였다. 산정된 특성유속들을 D'odorico and Rigon(2003)이 제시한 값과 비교함으로써 격자 기반의 GIUH 모형의 적용에 있어서 적정 공간해상도를 찾고자 하였다. 대상유역으로는 국제수문개발계획(IHP, International Hydrological Project)의 금강수계 보청천 유역 중 이평수위국을 출구로하는 소유역을 선정하였으며, DEM의 공간해상도는 수치지형도의 축척을 고려하여 1: 5,000의 경우 5, 10, 15, 20m를, 1: 25,000의 경우 20, 30, 50, 100, 150, 200m로 결정하였다. 분석 결과 격자 형태 GIUH의 특성유속을 산정을 위한 적정 공간해상도는 1:5,000의 경우 5m를, 1:25,000의 경우에는 20～50m의 범위를 적용하는 것이 타당할 것으로 판단된다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.5
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• pp.575-583
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• 2009

Various algorithms and methods, related to preprocessing of LiDAR data, are being developed and proposed. These methods are two ways, one of them is to use the regular form such as DSM or the image converted from raw LiDAR data, and the other is to use raw LiDAR data directly. The image processing method is one of representative method for the regular grid form data. This method is easy to apply to a numerical analysis technique and has an advantage of modeling and noise elimination through smoothing, but it lose the information during the data conversion. This study apply the image processing method to the irregular raw LiDAR data directly for the extracting ground information with minimized information loss and evaluate the extracting accuracy of ground information.

• Journal of Korea Spatial Information System Society
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• v.3 no.1 s.5
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• pp.89-94
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• 2001

The purpose of this study is development of the management system for convenient use of new address guide system for systematic management and use of spatial information gained by mapping of numerical map of building and road to large basic new address, survey and input of main gate, decision of the road session, naming and input of road name, grant of numbering of all houses and buildings, new address guide, real life geographical information and added information service on Web-site in Jecheon-city area. In this study, the development and establishment of new address management in local cities are designed by making full use of GIS function of client server based system. In the result, the effectiveness of new address management system of Jecheon- city could be highly increased owing to not only citizens' easy access but also easy availability of various informations necessary in life by developed its system.

• Geophysics and Geophysical Exploration
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• v.19 no.3
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• pp.153-163
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• 2016

In order to prevent ground collapses by groundwater level drawdown, we need to understand the groundwater flow and also make an analytical approach to the cause of the collapses. In this study, we used the result of the soil lab tests to compare and review the suitability of the various interaction equations about the relation between volumetric water content and the dielectric constant. In addition, using GPR (Ground-Penetrating Radar), we reviewed the possibility of calculating an estimate of dielectric constant. Lastly, we applied seepage analysis and stress-strain analysis to the sandy ground given by ground excavation. In comparison with the previous result of the soil lab tests, we similarly predicted the suction of unsaturated soil from results of stress-strain analysis considered the seepage force for the unsaturated soil.

• Korean Journal of Environmental Agriculture
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• v.6 no.2
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• pp.84-93
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• 1987

The water solubilities and vapor pressures of chlorothalonil and Command were measured following the guidelines of the U.S. EPA and OECD. Water solubility of the two compounds is consistent with respective values in the literature. However, the vapor pressures of Chlorothalonil and Command were 5,000 times$(2{\times}10^{-7}\;torr\;at\;25^{\circ}C)$ and 100 times$(<1{\times}10^{-6}\;torr\;at\;45^{\circ}C)$ lower than the literature values, respectively. Courteous use of the vapor pressure values in the handbooks is suggested. With this study, experimental difficulties involved were recognized. Based on the low vapor pressure of Command, the cause of the accidental bleach of non-target plants in the United States might not be attributed to the volatilization of Command, but to the drift during the application of the herbicide. These approaches will be utilized to predict the environmental fate of new chemicals under development, to screen the potential environmental pollutants among chemicals already in use, and to assess measures to minimize the hazards.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.3
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• pp.167-174
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• 2017

Antarctica, where ice sheet has been declined rapidly, should be monitored periodically. However, there are difficult to access for local survey or aircraft observation due to the vast and extreme environments of the polar regions. In order to overcome this problem, there have been a lot of studies by acquiring radar or laser data by satellite. It is also difficult to accurately measure the changes of the surface where is composed of snow or ice layer, and it is also difficult to product a high-resolution DEM. This study therefore aims to product DEMs of two periods using high-resolution KOMPSAT-3A stereo images, and DEM matching is implemented by the LZD(Least-squares Z-Differences) method to detect DEM changes in both periods. As a result, the proposed method could be suggested as comparing height differences of the two DEMs within 1m precision.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.3
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• pp.373-380
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• 2008

So far there have been many researches on machine-based recognition of handwritten digit. But we have not yet attained the level of performance that can be satisfactory to men. The dissatisfaction with the performance of machine comes from not only the low accuracy of recognition but also the dissimilarity of the recognition results between man and machine. To reduce the difference of machine from man we first made an experiment with the human recognition of handwritten digits and then inquiry into the way of the human recognition that makes the results of men different from that of machine. We found out the attributes that play an important role in the human recognition process through the analysis of the experimental results like uni- and bi-directional confused pairs of digits, several ones unmixed up with another and the redundancy of mis-recognition, and proposed the approach direction to be able to improve the accuracy of the machine-based recognition, and furthermore the similarity in the recognition results of men and machine on the basis of the found facts above.