• 천문학회지
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• 제14권1호
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• pp.37-42
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• 1981

In order to know how the magnetic field increases with density in interstellar clouds, we have analyzed observations of extinction and polarization for stars in the ${\rho}$ Oph molecular cloud complex. The size of grains in dense parts of the complex is estimated to be larger than the ones in diffuse interstellar clouds by about 15 percent in radii. Employing the Davis-Greenstein mechanism for grain alignment with this estimated grain size, we have put constraints on the exponent in the field-density relation $B{\propto}n^x:1/5{\leq}x{\leq}1/3$. It is concluded that magnetic field in gravitationally contracting clouds increases less steeply than the classical expectation based on the approximation of isotropic contraction with complete frozen-in flux.

• 천문학논총
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• 제27권4호
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• pp.231-234
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• 2012

We present preliminary results of supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) seen by AKARI as well as Spitzer. By examining the AKARI LMC survey and the Spitzer data, we have searched for IR counterparts to 45 known SNRs in the LMC and could identify 28 SNRs with associated IR emission. 13 SNRs among them are newly detected in IR bands. For the entire IR SNRs, we make a catalog containing general information and the AKARI and/or Spitzer fluxes. Using the catalog, their IR colors and the possible correlation of the IR fluxes with the X-ray fluxes are examined. For some interesting SNRs, we have performed NIR spectroscopy with AKARI. An aromatic feature at $3.3{\mu}m$ can be identified in LMC SNR N49. We investigate the characteristics of the IR features and discuss the PAH mission mechanism in SNRs.

• 한국연소학회지
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• 제10권2호
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• pp.35-41
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• 2005

Behaviors of lean premixed flame of propane/air and methane/air flame anchored by a pilot flame in a tube were investigated experimentally varying the mean velocity from 10 to 140 cm/s and the equivalence ratio from 0.45 to 0.8. Behaviors of both flames are divided into five regions of stable, flash-back, tail-out, flickering and vibrating. General characteristics of each region and Le number effect are investigated. Two main instabilities, flickering and vibration, are both unstable but the instability mechanism, the frequency and the amplitude of pressure fluctuation are different. In the edge of the vibrating region, pressure fluctuation repeats generation and extinction. Repeated growth and decrease of the amplitude of pressure fluctuation are explained by Rayleigh#s index.

• 한국초전도ㆍ저온공학회논문지
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• 제2권1호
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• pp.24-30
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• 2000

This paper present the characteristics of the internal induced voltage and arc phenomena in liquid helium at the energy transfer from a superconducting magnet to a load resistor. Especially generation mechanism of the oscillated wave from of the coil terminal voltage is analyzed by considering circuit constant of the superconducting magnet, load condition and arc resistance of the mechanical opening switch. The wavefront and peak portion of the voltage are strongly influenced by arc discharge triggered by the switch separation in liquid helium. Abrupt arc extinction leads to voltage oscillation with an enormous peak. It is suggested that the superconducting magnet should be designed to ensure the internal surge when arc is possibly formed by switch opening or coil short circuit between turns or layers. Finally, a suppression method of the oscillating surge is proposed based on the load condition.

• 생물정신의학
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• 제18권2호
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• pp.80-89
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• 2011

Pavlovian fear conditioning has been extensively studied for the understanding of neurobiological basis of memory and emotion. Pavlovian fear conditioning is an associative memory which forms when conditioned stimulus (CS) is paired with unconditioned stimulus (US) once or repeatedly. This behavioral model is also important for the understanding of anxiety disorders such as posttraumatic stress disorder. Here we describe the neural circuitry involved in fear conditioning and the molecular mechanisms underlying fear memory formation. During consolidation some memories fade out but other memories become stable and concrete. Emotion plays an important role in determining which memories will survive. Memory becomes unstable and editable again immediately after retrieval. It opens the possibility for us of modulating the established fear memory. It provides us with very efficient tools to improve the efficacy of cognitive-behavior therapy and other exposure-based therapy treating anxiety disorders.

• 천문학회보
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• 제43권1호
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• pp.62.3-63
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• 2018

Trends of Type Ia supernova (SN Ia) luminosities with the properties of host galaxies are important to study the underlying physics for an SN progenitor system and explosion mechanism. In the YONSEI SN catalog, we have a sample of ~600 SN and host data in the wider redshift range, and two independent light-curve models, SALT2 and MLCS2k2. From this catalog, here we present that SNe Ia in low-mass, globally and locally star-forming environments are fainter than those in high-mass, globally and locally passive environments, after light-curve shape and color or extinction corrections. Our results are then compared to previous studies, and show consistent results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.332-337
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• 2003

Oxygen-enriched non-premixed flame characteristics was investigated numerically with variation of dilution methods, which are Flue gas recirculation(FGR) and fuel injection recirculation(FIR). In order to compare flamelets in various oxygen-enrichment conditions reasonably, the adiabatic flame temperature and Damkoller number was held fixed by modulating amount of diluents to fuel and oxidizer stream and by varying global strain rate of flame respectively. Also modified GRI 3.0 reaction mechanism was utilized, which was able to predict oxygen-enriched methane flame correctly. Fundamental flame characteristics such as structure, heat release rate and extinction with FGR and FIR were compared in various oxygen enrichment conditions.

• 천문학회보
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• 제37권2호
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• pp.89.1-89.1
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• 2012

Type Ia Supernovae are known as one of the most reliable standard candle regarding to our understanding their explosion mechanism. Recently NIR photometry of SN Ia shows us better promise on the distance measurement. NIR peak luminosity is relatively independent of light curve shape and effect of extinction is obviously less than in optical wavelengths. Among NIR bands, Y-band photometry is suggested to have less scatter and reduced reddening effect than other NIR wavelengths, furthermore it is still unexplored regime to verify its utility. Here we report Y-band light curve analysis of M101 SN Ia to investigate how Y-band can help us to determine accurate distance to the galaxy.

• 한국화재소방학회논문지
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• 제22권3호
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• pp.221-227
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• 2008

본 연구에서는 FDS 코드를 이용하여 외부 자연풍에 의한 터널 내의 미세물분무 소화특성을 검토하였으며, 상세반응이 고려된 1차원 대향류 비예혼합화염을 이용하여 화염내부에서 미세물분무의 냉각 및 화학반응효과에 의한 소화현상을 규명하였다. 연구결과로서, 외부 자연풍의 유속 증가에 따라 고온 연기층의 분포 및 분무 특성의 큰 변화가 발생됨을 확인하였다. 외부 자연풍이 없는 경우에는 분무입자 직경이 작을수록 소화성능이 좋지만, 풍속이 증가함에 따라 입자직경이 클수록 소화성능이 좋아짐을 알 수 있었다. 자연풍은 입자의 화염면 침투를 방해할 뿐 아니라. 충분한 산소의 공급으로 화제 억제를 방해할 것으로 예측된다. 또한 자연풍이 존재하는 조건의 화염은 화염 신장효과에 의해 밀폐된 공간에서의 화염 보다 작은 양의 $H_2O$침투에 의해서도 소화될 수 있으며, $H_2O$의 화학반응에 의한 소화효과는 외부 자연풍의 유속에 크게 영향을 받지 않음을 확인하였다.

• 대한수의학회지
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• 제13권2호
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• pp.147-160
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• 1973

The present experiments proposed to pass judgement upon the suitability as the second intermediate host of Clonorchis sinensis, of three kinds of fresh-water fish by having them infected with the cercaria of Clonorchis sinensis and then observing the penetrating ability of the cercaria, and maturity, the process of degeneration and extinction, and infectivity of the metacercaria of Clonorchis sinensis. The following is a brief summary of the leading facts gained through the experiments; 1. P. parva was easily subject to invasion of the cercaria, A. signifer was much less subject to the invasion, and finally A. asmussi was hard to invade. And the infectivity of the cercariae was in proportion to their penetrating ability mentioned in the above. 2. The examination of the cercariae after having three kinds of fresh-water fish infected with them disclosed that 24 hours after the infection, all of the cercariae formed their cysts in muscle and the metacercariae kept growing, and that 7 days later the metacercariae were found folding their bodies twice, and that in 15 days the characteristic structure of the metacercariae was complete and they made a vigorous rotary movement intermittently. 3. Then the metacercariae came to a state of maturity and beyond this stage some metacercariae in P. parva started the process of degeneration and extinction in 133 days; some in A. asmussi, in 140 days; and A. signifer, in 70 days. As more days elapsed, their degeneration and extinction increased in number, and in 269 days all of them in A. signifer became dead while those in A. asmussi were all dead in 460 days. However almost all of them in P. parva survived even after 770 days. The results shown above revealed that P. parva was the most suitable as the second intermediate host among three kinds of fresh-water fish and that A. signifer and A. asmussi were not quite recommendable as the second intermediate host. The ability of the cercaria to invade fresh-water fish, and life span of the metacercaria within fresh-water fish vary outstandingly according to species of fresh-water fish. An explanation as to the mechanism must wait as the subject to be further pursued.