• 천문학회보
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• 제38권1호
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• pp.31.2-31.2
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• 2013

We use grid-based hydrodynamic simulations to study star formation in nuclear rings in barred galaxies. The gaseous medium is assumed to be infinitesimally thin, isothermal, and unmagnetized. To investigate various situations, we vary the total gas content in the bar regions and the bar growth time. We find that star formation rate (SFR) in a nuclear ring is determined by the mass inflow rate to the ring rather than the total gas mass in the ring. The SFR shows a strong primary burst and weak secondary bursts at early time, and declines to small values at late time. The primary burst is caused by the rapid gas infall to the ring due to the bar growth, with its duration and peak depending on the bar growth time. The secondary bursts result from re-infall of the ejected gas by star formation feedback of the primary burst. When the SFR is low, ages of young star clusters exhibit an azimuthal gradient along the ring since star formation takes place mostly near the contact points between the dust lanes and the nuclear ring. When the SFR is large, on the other hand, star formation is widely distributed throughout the whole length of the ring, with no apparent age gradient of star clusters. Regardless of SFR, star clusters have a positive radial age gradient, with younger clusters located closer to the ring, since the ring shrinks in size over time.

• 한국진공학회지
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• 제20권4호
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• pp.252-257
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• 2011

본 연구 그룹은 6H-SiC (0001)에서 성장시킨 그라핀 층에 흡착된 퓨란(furan)의 고리 형성과 전자적 성질을 원자 힘 현미경(Atomic Force Microscope : AFM), C K-edge에 대한 Near Edge X-ray Absorption Fine Structure (NEXAFS) 스펙트럼, 핵심부 준위 광전자 분광스펙트럼(Core-level Photoemission Spectroscopy : CLPES)을 이용하여 연구했다. 우리는 그라핀위에 흡착된 퓨란 분자들이 화학적 도핑이 가능한 산소기의 홀 전자쌍을 통하여 그라핀의 특성을 조절할 수 있는 화학적 기능화에 이용될 수 있다는 것을 알아냈다. 또한, 퓨란이 자발적으로 세 가지의 다른 결합 구조들 중 하나로 고리를 형성한다는 것과 그라핀 위에 퓨란에 의해 형성된 고리의 전자적 성질들이 AFM, NEXAFS, CLPES를 이용하여 각각 설명될 수 있다는 것을 보여주었다.

• 한국광물학회지
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• 제4권2호
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• pp.99-107
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• 1991

Three fully dehydrated fully Rb+-exchanged zeolite A single crystals have been prepared by the reduction of all Na+ ions in dehydrated Na12-A by rubidium vapor at various experimental conditions (220 $\leq$ T $\leq$ 33$0^{\circ}C$, 2 $\leq$ t $\leq$24 hours, and 0.1 $\leq$ PRb $\leq$ 1.1 Torr). Their structures were determined by single-crystal X-ray diffraction methods in the space group {{{{ RHO }}m3m (a=12.245(3) A) at 22(1)$^{\circ}C$. In these structures 12.6(2) to 13.5(2) Rb species are found per unit cell, more than the 12 Rb+ ions needed to balance the anionic charge of the zeolite framework, indication that the sorption of Rb0 has occurred. In each structure, three Rb+ ions per unit cell are located at the centers of 8-rings. Beyond that, the fractional occupancies observed are simply explained by two unit cell arrangments. In one, two Rb+ ions are in the sodalite unit near opposite 6-rings, six are in the large cavity near 6-ring, and one is in the large cavity near a 4-ring. In the other, three Rb species in the sodalite cavity (forming a triangle 3.7 A on an edge) each bond (3.4 A) through a 6-ring to an Rb species in the large cavity to give an (Rb6)4+ cluster of symmetry 3m (C3V). Five additional Rb+ ions fill the remaining large-cavity 6-ring sites.

• 디지털융복합연구
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• 제19권11호
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• pp.341-349
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• 2021

최근 조명 산업이 중요한 분야로 인식되면서 PQR (Photonic Quantum Ring) 소자는 LED(Light Emitting Diode)를 대체할 수 있는 차세대 광원이 될 전망이다. 본 연구에서는 기존 연구와 유사한 결과를 검증하고, 소자의 광특성을 분석하기 위해 광섬유가 연결된 스테이지에 x, y, z 좌표를 입력하면 자동으로 이동하며, 또한, 소자에 광섬유를 근접시키는 NSOM (Near field scanning optical microscopy) 장치를 추가한 측정 시스템을 이용하여 소자의 광특성 실험과 공진 및 어레이 소자의 광특성 시뮬레이션을 통해 조명용 소자로 가능성을 검증하고자 하였다. 이를 위해 메사와 홀 형태가 동시에 존재하는 메사 직경 40㎛, 홀 직경 3㎛의 소자를 제작하여 소자의 근접장으로 PQR 소자는 ㎂에서 동작하며, 메사와 홀 소자는 서로 독립적으로 구동됨을 관찰하였다. 위치에 따른 소자의 광파장 스펙트럼을 측정하여 메사와 홀 소자에 의한 커플링 현상을 처음으로 확인하였다.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제10권4호
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• pp.199-206
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• 2003

Let N be a right near-ring. N is said to be strongly reduced if, for $a\inN$, $a^2 \in N_{c}$ implies $a\;\in\;N_{c}$, or equivalently, for $a\inN$ and any positive integer n, $a^{n} \in N_{c}$ implies $a\;\in\;N_{c}$, where $N_{c}$ denotes the constant part of N. We will show that strong reducedness is equivalent to condition (ⅱ) of Reddy and Murty's property $(^{\ast})$ (cf. [Reddy & Murty: On strongly regular near-rings. Proc. Edinburgh Math. Soc. (2) 27 (1984), no. 1, 61-64]), and that condition (ⅰ) of Reddy and Murty's property $(^{\ast})$ follows from strong reducedness. Also, we will investigate some characterizations of strongly reduced near-rings and their properties. Using strong reducedness, we characterize left strongly regular near-rings and ($P_{0}$)-near-rings.

• 대한수학회논문집
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• 제3권1호
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• pp.13-16
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• 1988

• East Asian mathematical journal
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• 제17권2호
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• pp.287-295
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• 2001

• 한국수학교육학회지시리즈A:수학교육
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• 제22권2호
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• pp.13-15
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• 1984

• Kyungpook Mathematical Journal
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• 제20권2호
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• pp.183-188
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• 1980

• 천문학회보
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• 제8권
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• pp.9.2-9.2
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• 1983