• 한국결정성장학회지
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• 제15권4호
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• pp.129-134
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• 2005

초크랄스키 단결정장치내 실리콘 유동의 자기장효과에 대한 수치해석을 하였다. 8" 단결정 성장과정에서 난류 모형을 사용하여 수송현상을 계산하였다. 도가니 회전수가 작으면 자연대류가 지배적이었다. 도가니 회전수가 증가할수록 강제대류가 증가되며 온도 분포는 더 넓어진다. cusp 자기장을 인가하면 도가니근처의 유동이 크게 감소하며 온도분포는 전도의 경우와 비슷해진다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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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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• 제15권2호
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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.

• 지질공학
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• 제12권2호
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• pp.235-238
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• 2002

• 한국수학사학회지
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• 제11권2호
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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.

• 한국전통조경학회지
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• 제32권1호
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• pp.1-9
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• 2014

본 연구는 밀양 영남루가 갖고 있는 경관적인 특징을 밝히기 위해 영남루와 관련된 354편의 시문에 대한 핵심어(keyword)분석과 시문 요소 분석, 그리고 보조적으로 CAD를 활용한 지형분석과 고지도 분석을 한 결과는 다음과 같다. 영남루 시문에 대한 핵심어를 분석해 보면 명승이 56회, 장강(長江)과 장림(長林)이 39회, 최고 제일경관이 31회, 큰 들판 조망경관이 19회, 천겹 산악경관이 14회로 나타났는데, 이것을 모두 합치면 159회로 전체 시문의 44.9%에 해당한다. 영남루 시문에 나타난 자연요소를 분석해 본 결과 자연현상(44%), 지형(33%), 식물(14%), 동물(9%) 순이었는데, 자연현상 가운데에는 특히 하늘천(天)이41회로 제일 많았는데, 이것은 영남루의 '천(天)'의 경관이 뛰어나기 때문이다. 또 영남루 지형경관의 특징은 '강 흐름'과 '모래섬'이었다. 또한 영남루에서는 악기 출현빈도(8%)가 높아 다양한 악기를 공연하는 공간이었다. 이러한 특징들 때문에 영남루가 고려시대부터 제일가는 누각이라는 평가를 받아왔다.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2002년도 11월 학술대회지
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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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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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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• 제49권3호
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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.

• 통합자연과학논문집
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• 제6권2호
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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.