• 천문학회보
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• 제36권2호
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• pp.102.1-102.1
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• 2011

In this study we use three-dimensional magnetohydrodynamic simulations to investigate how the dynamic state of emerging magnetic field is related to the twist of field lines. Emerging magnetic field forms a magnetic structure on the Sun where various kinds of activity such as solar flares, jets, and coronal mass ejections are observed. To understand the physical mechanism for producing such activity, we have to know the dynamic nature of this structure. Since flares are the manifestation of rapidly dissipating electric current in the corona, we also investigate the distribution of current density inside the structure and examine how it depends on the field-line twist. To demonstrate the dynamic structure of emerging magnetic field, we focus on the factors characterizing the geometric property and stratification of emerging magnetic field, such as the curvature of field line and the scale height of field strength. These two factors show that emerging field forms a two-part structure in which the central part is close to a force-free state while the outer marginal part is in a fairly dynamic state where magnetic pressure force is dominant. We discuss how the field-line twist affects the two-part structure and also explain a possible relation between electric current structure and sigmoid observed in a preflare phase.

• 천문학회보
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• 제37권1호
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• pp.86.1-86.1
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• 2012

The MHD virial theorem applied for observed photospheric field may be the one of way to estimate magnetic energy of generally invisible coronal magnetic structure. However, the photospheric field is not in a force-free state, so the application of virial theory needs some care. Here we use a series of MHD simulations of emerging field to investigate how we can apply the virial theorem to the emerging field. In early emerging phase, virial energy has a minus value although positive area at the photosphere is continuously generated toward a late emerging phase. We discuss why this tendency occurs. Then we derive the critical height where the actual emerging magnetic energy is almost comparable to the virial energy. If the difference between virial energy and magnetic energy becomes 10 percentage of the magnetic energy, we define this is the critical height, and assume the emerging field is close to force-free. We also discuss how the critical height changes with the initial twist of an emerging flux tube.

• 천문학회보
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• 제37권1호
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• pp.87.1-87.1
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• 2012

We use three-dimensional magnetohydrodynamic simulations to investigate how the dynamic state of emerging magnetic field is related to the twist of field lines. Emergence of magnetic field is considered as one of the key physical process producing solar activity such as flares, jets, and coronal mass ejections. To understand these activities we have to know dynamic nature and electric current structure provided by emerging magnetic field. To demonstrate dynamic nature of field lines, we focus on the factors such as curvature of magnetic field line and scale height of magnetic field strength. These factors show that strong twist case forms two-part structure in which the central part is close to a force-free state while the outer marginal part is in a fairly dynamic state. For weak twist case, it still shows two-part structure but the tendency becomes weaker than strong twist case. We discuss how the curvature distribution affects the dynamic nature of emerging magnetic field. We also investigate electric current distribution provided by emerging field lines to show a possible relation between electric current structure and sigmoid observed in a preflare phase.

• 경영과학
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• 제32권4호
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• pp.1-18
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• 2015

On UX/UI fields, understanding emerging technology is important for preoccupancy of a future market. Most of emerging field searching methods are qualitative methods. However, it is suitable for large companies to adduce its milestone, not for small enterprises. Thus, this study aims at purposing the improvement of utilizability for research field searching processes. We draw core patents with modified patent citation data, apply the Girvan-Newman clustering method based on bibliographic coupling patent relationship and then, draw emerging technology research UX/UI fields. Finally, the results were validated in comparison with a report on emerging research.

• 경영과학
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• 제23권3호
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• pp.77-93
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• 2006

In the highly competitive world, there has been a concomitant increase in the need for the research and planning methodology, which can perform an advanced assessment of technological opportunities and an early Perception of threats and possibilities of the emerging technology according to the nation's economic and social status. This research is aiming to provide indicators and visualization methods to measure the latest research trend and aspect underlying scientific and technological documents to researchers and policy planners using 'Co-word Analysis' Organic light emitting diodes(OLED) is an emerging technology in various fields of display and which has a highly prospective market value. In this paper, we presented an analysis on OLED. Co-word analysis was employed to reveal patterns and trends in the OLED fields by measuring the association strength of terms representatives of relevant publications or other texts produced in the OLED field. Data were collected from SCI and the critical keywords could De extracted from the author keywords. These extracted keywords were further standardized. In order to trace the dynamic changes in the OLED field, we presented a variety of technology mapping. The results showed that the OLED field has some established research theme and also rapidly transforms to embrace new themes.

• 천문학회보
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• 제42권2호
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• pp.81.3-81.3
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• 2017

In this paper, we report a small-scale emerging island and double arc loops, which are associated with a M6.5 flare, in Active Region 12371. We investigate the spatial and temporal changes of both photospheric magnetic fields using SDO/HMI data and coronal magnetic structures obtained from nonliner force-free field (NLFFF) extrapolation. From the vector magnetograms, we find a small-scale emerging island near the main polarityy inversion line about three hours before the flare. The island has a strong shear angle, which is determined by difference between transverse component of observed field and potential field, of around 90 degrees. Furthermore, the NLFFF well reproduces a sigmoidal structure seen in SDO/AIA 94, which is consistent with the double arc loops configuration suggested by Ishiguro and Kusano (2017) who introduced a magnetic configuration showing the double arc instability. The observed emerging island is located among the double arc loops, which is also supproted by their model. Finally, there was an eruption (M6.5 flare) associated with the loops. We discuss a possible role of the double arc instability for the eruption.

• Advances in nano research
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• 제2권1호
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• pp.15-22
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• 2014

In recent years, spins of confined carriers in quantum dots are promising candidates for the logical units in quantum computers. In many concepts developed so far, the individual spin q-bits are being manipulated by magnetic fields, which is difficult to achieve. In the current research the recent developments of spin based quantum computing has been reviewed. Then, Single-hole spin in a molecular quantum dots with less energy and more speed has been electrically manipulated and the results have been compared with the magnetic manipulating of the spin.

• 한국콘텐츠학회논문지
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• 제8권2호
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• pp.231-238
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• 2008

미래 유망연구 및 기술의 선정을 위한 방법론의 개발과 이를 통한 구체적인 아이템 선정을 위한 연구가 추진되고 있다. 본 논문에서 우리는 건설교통분야의 유망연구영역 도출을 위하여 과학계량학(scientometrics)을 활용한다. 과학계량학적 분석을 위하여 Scopus 데이터베이스, 상위 1%에 해당하는 고인용논문, 서지결합법, cosine 계수, 계층적 클러스터링 기법을 사용하며, 그 분석결과는 전문가들에 의해 재검증을 실시한다. 우리는 과학계량학적 분석방법을 자세히 설명하고, 미래유망연구영역 및 기술도출의 객관적인 방법으로서 과학계량학적 분석의 가능성을 보여준다.

• 천문학회보
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• 제43권2호
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• pp.58.2-58.2
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• 2018

Theoretically, the magnetic helicity transport flux through the solar surface into the upper atmosphere can be estimated indefinitely precisely by magnetic field footpoint tracking if the observational resolution is infinitely fine, even with magnetic flux emergence or submergence. In reality, the temporal and spatial resolutions of observations are limited. When magnetic flux emerging or submerging, the footpoint velocity goes to infinity and the normal magnetic field vanishes at the polarity inversion line. A finite observational resolution thus generates a blackout area in helicity flux estimation near the polarity inversion line. It is questioned how much magnetic helicity is underestimated with a footpoint tracking method due to the absence of information in the blackout area. We adopt the analytical models of Gold-Hoyle and Lundquist force-free flux ropes and let them emerging from below the solar surface. The observation and the helicity integration can start at different emerging stages of the flux rope, i.e., the photospheric plane initially cuts the flux rope at different levels. We calculate the magnetic helicity of the flux rope below the photospheric level, which is eventually to emerge, except the helicity hidden in the region to be swept by the blackout area with different widths. Our calculation suggests that the error in the integrated helicity flux estimate is about half of the real value or even larger when small scale magnetic structures emerge into the solar atmosphere.

• Journal of Smart Tourism
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• 제1권1호
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• pp.1-2
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• 2021