• Journal of Environmental Impact Assessment
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• v.8 no.2
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• pp.73-82
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• 1999

This study analyzed the relationship between NDVI(Normalized Difference Vegetation Index) and urban heat island in three cities: Daegu, Kyungju, and Pohang for understanding the degree of nature conservation concentrating in the transition zone of them. Daegu city is the third city in Korea which has a dense population. Kyungju is a traditional city which has good nature. Pohang is an industrial city which has those of characters of Daegu and Kyungju. Landsat 1M data in May 17, 1997 were used for the analysis of heat island. There were about four theoretical models to estimate the surface temperature from TM data: Two-point linear model, Linear regression model, Quadratic regression model, and Cubic regression model. In this study, Linear regression model had been utilized to analyze the urban heat island. On the resultant images, the transition zone of Daegu was urbanized more extremely than those of other two cities. It is thought that the analysis of relationship between NDVI and surface temperature, used in this study, is regarded as one of effective methodologies for urban-environmental detection from satellite imageries.

• Journal for History of Mathematics
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• v.30 no.4
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• pp.247-258
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• 2017

The goal of this essay is to examine metaphors for mathematics and to discuss philosophical problems related to them. Two metaphors for mathematics are well known. One is a tree and the other is a building. The former was proposed by Pasch, and the latter by Hilbert. The difference between these metaphors comes from different philosophies. Pasch's philosophy is a combination of empiricism and deductivism, and Hilbert's is formalism whose final task is to prove the consistency of mathematics. In this essay, I try to combine two metaphors from the standpoint that 'mathematics is a part of the ecosystem of science', because each of them is not good enough to reflect the holistic mathematics. In order to understand mathematics holistically, I suggest the criteria of the desirable philosophy of mathematics. The criteria consists of three categories: philosophy, history, and practice. According to the criteria, I argue that it is necessary to pay attention to Pasch's philosophy of mathematics as having more explanatory power than Hilbert's, though formalism is the dominant paradigm of modern mathematics. The reason why Pasch's philosophy is more explanatory is that it contains empirical nature. Modern philosophy of mathematics also tends to emphasize the empirical nature, and the synthesis of forms with contents agrees with the ecological analogy for mathematics.

• Transactions on Electrical and Electronic Materials
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• v.15 no.6
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• pp.291-296
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• 2014

In recent years, researchers have extensively investigated polymers filled with inorganic nanoparticles because these materials present improved physical properties relative to those of conventional unfilled polymers. Oxides, silica in particular, are the most commonly used inorganic particles because they possess good properties and can be fabricated at a low cost. However, oxides are hydrophilic in nature, and this leads to the presence of water at the interface between the nanoparticles and the polymer matrix. Due to the predominance of particle-matrix interfaces in nanocomposites, the presence of water at the interlayer region can be problematic. Moreover, the hydrophobic nature of most polymers, particularly for polyolefins such as polyethylene, may make it difficult to remove this interfacial water. In this paper, as-received and moistened samples of agglomerated nanosilica/polyethylene were dried using an isothermal treatment at $60^{\circ}C$, and the efficacy of this treatment was studied using dielectric spectroscopy. The Maxwell-Wagner-Sillars relaxation peaks were observed to shift to lower frequencies by three decades, and this was linked to a modification of the water content, due to drying, at the interfaces between silica and polyethylene and at the interfaces within the nanosilica agglomerates. The evolution of the extracted retardation time is explained by the nanosilica hydrophily and the free volume introduced by the nanoparticles.

• Journal of Korean Medical classics
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• v.25 no.3
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• pp.149-158
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• 2012

Objectives : In modern meditation, psychologic therapy and happy life have been in the main status. The aim of this study is to search about the value of modern meditation systematically and to summarize the contents on the meditation in "Donguibogam(東醫寶鑑)". Methods : We investigated the meditation-related materials in "Donguibogam(東醫寶鑑)", and discussed them in comparison with the other contents found in "Huangdi's Internal Classic(黃帝內經)" and some scriptures on meditation and self-discipline. Results : The mind-body concept in Korean Medicine takes meditation and self-discipline into main consideration. Meditation and self-discipline mean the endless pursuing the nature of mind and body, thus leading to self-practice about the true meaning of life. "Donguibogam(東醫寶鑑)" includes the views on the meditation and self-discipline from the various angles based on Confucianism, Buddhism and Taoism. Conclusions : Meditation and self-discipline rooted in East Asian tradition are good ways to reach the true nature of mind-body system of universe and to help people seek happiness in their lives.

• Journal of Korean Library and Information Science Society
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• v.36 no.2
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• pp.1-12
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• 2005

The purpose of this study is to investigate the nature and the pattern of oral book reviewing in order to prepare the methodological basis of systematic education and training for the oral book reviewer Students should have opportunities to exercise themselves in oral book reviewing. We need experienced teachers, space, facilities, and supplies to train them to be a member of reviewer group at modern intellectual society. And there are so many prerequisites like good copy, delivery technique, understanding the specialty of broadcasting language and the distinctions of the oral review from the written review for successful performance as reviewer.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.4
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• pp.462-470
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• 2015

In this study, we analyze the impacts of the trapezoidal fin shape of a double-gate FinFET on the electrical characteristics of circuits. The trapezoidal nature of a fin body is generated by varying the angle of the sidewall of the FinFET. A technology computer-aided-design (TCAD) simulation shows that the on-state current increases, and the capacitance becomes larger, as the bottom fin width increases. Several circuit performance metrics for both digital and analog circuits, such as the fan-out 4 (FO4) delay, ring oscillator (RO) frequency, and cut-off frequency, are evaluated with mixed-mode simulations using the 3D TCAD tool. The trapezoidal nature of the FinFET results in different effects on the driving current and gate capacitance. As a result, the propagation delay of an inverter decreases as the angle increases because of the higher on-current, and the FO4 speed and RO frequency increase as the angle increases but decrease for wider angles because of the higher impact on the capacitance rather than the driving strength. Finally, the simulation reveals that the trapezoidal angle range from $10^{\circ}$ to $20^{\circ}$ is a good tradeoff between larger on-current and higher capacitance for an optimum trapezoidal FinFET shape.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1477-1491
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• 2017

Inspired by the multi-scale nature of hippocampal place cells, a biologically inspired model based on a multi-scale spatial representation for goal-directed navigation is proposed in order to achieve robotic spatial cognition and autonomous navigation. First, a map of the place cells is constructed in different scales, which is used for encoding the spatial environment. Then, the firing rate of the place cells in each layer is calculated by the Gaussian function as the input of the Q-learning process. The robot decides on its next direction for movement through several candidate actions according to the rules of action selection. After several training trials, the robot can accumulate experiential knowledge and thus learn an appropriate navigation policy to find its goal. The results in simulation show that, in contrast to the other two methods(G-Q, S-Q), the multi-scale model presented in this paper is not only in line with the multi-scale nature of place cells, but also has a faster learning potential to find the optimized path to the goal. Additionally, this method also has a good ability to complete the goal-directed navigation task in large space and in the environments with obstacles.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.39 no.5
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• pp.203-206
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• 2013

Statistics is the science of data. As the foundation of scientific knowledge, data refers to evidentiary facts from the nature of reality by human action, observation, or experiment. Clinicians should be aware of the conditions of good data to support the validity of clinical modalities in reading scientific articles, one of the resources to revise or update their clinical knowledge and skills. The cause-effect link between clinical modality and outcome is ascertained as pattern statistic. The uniformity of nature guarantees the recurrence of data as the basic scientific evidence. Variation statistics are examined for patterns of recurrence. This provides information on the probability of recurrence of the cause-effect phenomenon. Multiple causal factors of natural phenomenon need a counterproof of absence in terms of the control group. A pattern of relation between a causal factor and an effect becomes recognizable, and thus, should be estimated as relation statistic. The type and meaning of each relation statistic should be well-understood. A study regarding a sample from the population of wide variations require clinicians to be aware of error statistics due to random chance. Incomplete human sense, coarse measurement instrument, and preconceived idea as a hypothesis that tends to bias the research, which gives rise to the necessity of keen critical independent mind with regard to the reported data.

• Journal of Korean Society on Water Environment
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• v.30 no.6
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• pp.612-621
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• 2014

Physicochemical factors and the phytoplankton communities in the downstream area of Namhan-River were investigated from June 2012 to November 2013. We also assessed water quality using biological water quality indices. Total nitrogen was 2.4 mg/L, total phosphorus was 0.04 mg/L, and biological oxygen demand was 1.1 mg/L. This resulted in a level 2 (Ib, good) water quality rating. A total of 259 phytoplankton taxa were classified, consisting of 26 families, two subfamilies, 64 genera, 222 species, 32 varieties, and five formas. Bacillariophyceae dominated during a1l seasons and at all sites. The dominant species were Aulacoseira granulata, Cyclotella meneghiniana, C. stelligera, Melosira varians, Cocconeis placentula var. lineata, Nitzschia palea, N. amphibia, Cymbella minuta, and Achnanthes convergens. The diatom assemblage index for organic pollution values was level A-D, and TDI was level B-D. P-IBI at most sites was at the M (moderate) level, but TSI was at the E (eutrophic) level. Most indices dropped from upstream to downstream.

• Tribology and Lubricants
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• v.33 no.6
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• pp.256-262
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• 2017

Molten zinc plating is a process in which zinc is thinly coated over a metallic or non-metallic surface. It is used in various industrial fields for corrosion resistance and decoration. During the process, a steel sheet is passed through a roll that rotates inside the molten zinc liquid in the temperature range of $460^{\circ}C$ to $680^{\circ}C$, and the plating liquid flows into the roll causing abrasion and erosion of the roll surface. This problem is known to accelerate the replacement cycle of the roll and cause considerable economic loss owing to production line stoppage. Here, we propose a mechanism that operates at high temperature and pressure with a labyrinth type seal design to resolve this problem. We theoretically investigate the flow of the plating solution inside the seal and compute the minimum rotation speed required to prevent the plating solution from entering the seal chamber. In addition, we calculate the thermal deformation of the seal during operation and display thermally deformed dimensions at high temperatures. To verify the theoretical results, we perform experiments using pilot test equipment working in the actual plating environment. The experimental results are in good agreement with theoretical results. We expect our results to contribute towards the extension of the roll's life span and thereby reduce the economic losses.