• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.4
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• pp.129-134
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• 2005

A numerical analysis was performed on magnetic field effects of silicon melt motion in Czochralski crystal puller. The turbulent modeling was used to simulate the transport phenomena in 18' single crystal growing process. For small crucible angular velocity, the natural convection is dominant. As the crucible angular velocity is increased, the forced convection is increased and the distribution of temperature profiles is broadened. The cusp magnetic field reduces effectively the natural and forced convection near the crucible and the temperature profiles of the silicon fluids is similar in the case of conduction.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.994-996
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• 1999

Hygrothermal aging at the elevated temperature induces the long-term degradation of the epoxy resin. We investigated the effects of hydrothermal stress on the dielectric breakdown phenomena of epoxy composite filled with natural zeolite. The cured specimens absorbed the moisture in the autoclave at $120^{\circ}C$. $T_g$ of the deteriorated composite by moisture absorption decreased. The dielectric breakdown strength decreased with the moisture absorption cycle. It was concluded that the thermal stress and the high water-vapour-pressure deteriorated the natural zeolite filled epoxy resin system, consequently and the tree growth rate increased.

• Environmental Engineering Research
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• v.15 no.2
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• pp.85-91
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• 2010

Romania aims to adopt and implement the European Union's legislation, also including that for the field of water management. Like other countries, groundwater in Romania is locally polluted from point sources, such as leaking landfills, as well as from diffuse pollution sources, include fertilizers, pesticides and leakages from sewers, in urbanized areas. Diffuse pollution can also occur indirectly, by over-exploitation of groundwater wells, resulting in salt water intrusion, as well as from mining and exploitation of mineral aggregates. Romania has quite an intensive monitoring scheme to measure groundwater quality in phreatic and confined aquifers. The purpose of the work resumed in this paper was to derive natural background levels (NBL) for groundwater in order to distinguish the natural elevated concentrations of some substances (natural phenomena) from point and diffuse pollution (anthropogenic phenomena). Based on these NBLs, threshold values (TV) for groundwater will be set according to the requirements of the European Water Framework Directive and the related Groundwater Directive. This paper describes the results of a study for the derivation of NBL and TV in a pilot Groundwater Body. Also, the process and draft results for extrapolating this work for all Romanian groundwater bodies is explained, as well as points for future consideration with respect to monitoring and management.

• The Journal of Engineering Geology
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• v.12 no.2
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• pp.235-238
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• 2002

• Journal for History of Mathematics
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• v.11 no.2
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• pp.55-62
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• 1998

This paper aims to analyze the phenomena of eighteenth-century mathematics and to find the "metaphysics" of the period which made them possible. It shows that mathematics in eighteenth-century was "mixed" and result-oriented and that eighteenth-century metaphysics emphasized the real and natural.he real and natural.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.1
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• pp.1-9
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• 2014

The purpose of this study was to identify the landscape characteristics of Youngnam-Lu by performing text analysis of related Korean poems over 600 years. A total of 354 poems were quantitatively analyzed for keywords and terms in particular categories such as nature. As a subsidiary analysis, topographic map was examined using CAD along with analysis of antique maps. Of the 354 poems reviewed, keywords frequently used are: 'Scenic sites'- 56 times, 'Long river' (長江) and 'Long stretched forest'(長林) - 39 times each, 'Superb scenery'- 31 times, 'Large field scenery'- 19 times, and 'Thousand-layered mountain view' - 14 times. In total, these keywords occurred 159 times in 44.9 % of these poems.1) The words used frequently in these poems, especially for those fall under category of nature, can be scored into different subcategories such as natural phenomena and geographical features. Occurrences of terms in each subcategory were main criteria for the analysis and the following is a list of subcategories with frequency in descending order: Natural phenomena (44%), geographical features (33%), plants (14%), and animals (9%). Among natural phenomena, phenomena related to sky were most frequent, 41 times, which might be due to superb sky view from Youngnam-Lu. Also geographical features of Youngnam-Lu were reflected in these poems, and the most prominent features were 'flow of the river' and 'Sand island' located in the Milyang River. These poems contained fairly large number of terms related to musical instruments (8%) which suggest that Young-Nam-Lu as a place where various musical instruments performances were held.

• Proceedings of the KSPS conference
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• 2002.11a
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• pp.169-172
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• 2002

English is one of the stress-timed languages and has much more dynamic rhythm, stress and the tendency toward the isochronism of stressed syllables. It goes with various English utterance restructuring, irrespective of the pauses by syntactic boundaries, and post-lexically phonological phenomena. Specifically in the real speech acts, the natural utterances of fluent speakers or the broadcasting speech cause much more various English restructuring and phonological phenomena. This has been an obstacle for students in speaking fluent English and understanding normal speech. Therefore, this study tried to focus the most problematic factor in English speaking and listening difficulty on English restructuring and post-lexically phonological phenomena caused by stress-timed rhythm and, second, to point out the importance of teaching English rhythm bearing that in mind.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.178-183
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• 2004

This paper presents phenomena of vibration and noise due to acoustic resonance in tube bank of a large fossil power plant. The phenomena of acoustic resonance may arise when the vortex shedding frequency coincides with the acoustic natural frequency. In this system dominant frequency of vibration and noise was 37.5Hz. The $3^{rd}$ acoustic natural frequency calculated was 37.2 Hz. When the difference of vortex shedding frequency and acoustic natural frequency is within ${\pm}20%$, acoustic resonance could occur. If system is the state of acoustic resonance, vibration and noise become large. In order to prevent acoustic resonance, anti-noise baffle should be installed in the tube bank. In the case of installing baffle, we should consider the number of baffle and the effect of acoustic mode due to baffle extension length. To do this, we did acoustic mode analysis. After installing anti-noise baffle, acoustic resonance was disappeared and vibration magnitude and noise level was reduced dramatically.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.466-475
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• 2017

Coolant mixing under natural circulation flow regime constitutes a key parameter that may play a role in the course of an accidental transient in a nuclear pressurized water reactor. This issue has motivated some experimental investigations carried out within the OECD/NEA PKL projects. The aim was to assess the coolant mixing phenomenon in the reactor pressure vessel downcomer and the core lower plenum under several asymmetric steady and unsteady flow conditions, and to provide experimental data for code validations. Former studies addressed the mixing phenomenon using, on the one hand, one-dimensional computational approaches with cross flows that are not fully validated under transient conditions and, on the other hand, expensive computational fluid dynamic tools that are not always justified for large-scale macroscopic phenomena. In the current framework, an unsteady coolant mixing experiment carried out in the Rossendorf coolant mixing test facility is simulated using the three-dimensional porous media capabilities of the thermal-hydraulic system CATHARE code. The current study allows highlighting the current capabilities of these codes and their suitability for reproducing the main phenomena occurring during asymmetric transient natural circulation mixing conditions.

• Journal of Integrative Natural Science
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• v.6 no.2
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• pp.118-123
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• 2013

Korea, which is located in the middle-latitude area of the northern hemisphere, has four seasons. These seasons can be classified based on their months, mean temperatures, biology and natural phenomena. In this study, climatic changes were identified by biotic and temperature seasons, changing trends were compared by season, and the appropriateness of the biotic phenomena for the biotic season classification was examined. The data for this study included the mean temperatures, and biology phenomenon observation dates, which had been observed for 38 years from the ASOSs in seven Gwangju and Jeonnam regions. Limitations were found in the classification of the temperature and biotic seasons. Especially in the case of the biotic season based on a single life, the points of the first sighting and the initial sound fluctuated so much that the accuracy of the results was not guaranteed. Therefore, the life species had to be selected subject to detailed verification and accurate specifications, and to be applied to the meteorological phenomena. In addition, there were lives in the standard biology that could no longer be observed because of environmental pollution and climatic change, which indicates the need to protect the existing standard biology.