• 천문학회지
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• 제34권4호
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• pp.181-190
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• 2001

The advent of robust, reliable and accurate higher order Godunov schemes for many of the systems of equations of interest in computational astrophysics has made it important to understand how to solve them in multi-scale fashion. This is so because the physics associated with astrophysical phenomena evolves in multi-scale fashion and we wish to arrive at a multi-scale simulational capability to represent the physics. Because astrophysical systems have magnetic fields, multi-scale magnetohydrodynamics (MHD) is of especial interest. In this paper we first discuss general issues in adaptive mesh refinement (AMR), We then focus on the important issues in carrying out divergence-free AMR-MHD and catalogue the progress we have made in that area. We show that AMR methods lend themselves to easy parallelization. We then discuss applications of the RIEMANN framework for AMR-MHD to problems in computational astophysics.

• 천문학논총
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• 제30권2호
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• pp.163-167
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• 2015

We have carried out integral field unit (IFU) spectroscopy of $H{\alpha}$, [$N{\small{II}}$] and [$O{\small{III}}$] emission lines for a sample of Galactic planetary nebulae (PNe) with Wolf-Rayet (WR) stars and weak emission-line stars (wels). Comparing their spatially-resolved kinematic observations with morpho-kinematic models allowed us to disentangle their three-dimensional gaseous structures. Our results indicate that these PNe have axisymmetric morphologies, either bipolar or elliptical. In many cases the associated kinematic maps for the PNe around hot central stars also reveal the presence of so-called fast low-ionization emission regions.

• 천문학논총
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• 제30권2호
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• pp.159-161
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• 2015

We have carried out optical spectroscopic measurements of emission lines for a sample of Galactic planetary nebulae with Wolf-Rayet (WR) stars and weak emission-line stars (wels). The plasma diagnostics and elemental abundance analysis have been done using both collisionally excited lines (CELs) and optical recombination lines (ORLs). It was found that the abundance discrepancy factors ($ADF{\equiv}ORL/CEL$) are closely correlated with the difference between temperatures derived from forbidden lines and those from $He\;{\small{I}}$ recombination lines, implying the existence of H-deficient materials embedded in the nebula. The $H{\beta}$ surface brightness correlations suggest that they might be also related to the nebular evolution.

• 정보통신설비학회논문지
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• 제9권1호
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• pp.29-34
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• 2010

In this study, we realized the broadband home gateway system of dual mode based upon EDR 2~3Mbps transmission speed and 300Mbps of 802.11n, In broadcasting and telecommunication convergence networks to deliver multimedia services, high-quality home. The bluetooth module is designed to use general low rate data speed service and the 802.11n module also is designed to use high rate speed service at various home network situation. The dual mode home gateway system, bluetooth and 802.l1n module, is well realized for many specification such as emission power, spurious power, impedance matching, frequency channel test.

• 천문학회지
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• 제52권5호
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• pp.173-180
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• 2019

We present IR flux density measurements, models of the broadband SED, and results of SED modeling for the Pulsar Wind Nebula (PWN) 3C 58. We find that the Herschel flux density seems to be slightly lower than suggested by interpolation of previous measurements in nearby wavebands, implying that there may be multiple electron populations in 3C 58. We model the SED using a simple stationary one-zone and a more realistic time-evolving multi-zone scenario. The latter includes variations of flow properties in the PWN (injected energy, magnetic field, and bulk speed), radiative energy losses, adiabatic expansion, and diffusion, similar to previous PWN models. From the modeling, we find that a PWN age of 2900-5400 yrs is preferred and that there may be excess emission at ${\sim}10^{11}Hz$. The latter may imply multiple populations of electrons in the PWN.

• 천문학논총
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• 제33권3호
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• pp.45-57
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• 2018

Low-mass star-formation studies deal with the birth of individual solar-type stars as it occurs in nearby molecular clouds. While this isolated mode of star formation may not represent the most common form of stellar birth, its study often provides first evidence for the general ingredients of star formation, such as gravitational infall, disk formation, or outflow acceleration. Here I briefly review the current status and the main challenges in our understanding of low-mass star formation, with emphasis in the still mysterious pre-stellar phase. In addition to presenting by-now classical work, I also show how ALMA is starting to play a decisive role driving progress in this field.

• International Journal of Computer Science & Network Security
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• 제24권8호
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• pp.153-158
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• 2024

This paper is an extended paper showing the role of Decision Support Systems (DSS) in other fields of Marketing Management (M.Mgnt). DSS facilitates in decision making many M.Mgnt concepts and Customer Relationship Management (CRM) is one of them and it depends on the firm's tasks for developing and retaining customers while achieving their satisfaction and enhancing the sense of belongingness for their products and services. Profit maximization, the process of customer value, and building strategic values for the firm are the three empirical benefits of CRM that are achieved through analytical, operational, and direction (AOD) capabilities respectively. This research focuses on the application of DSS models of what-if analysis (WIA) for CRM at (AOD) and also shows the dependence on the Information Success model (ISM). Hypothetical data are analyzed for (AOD) by three types of (WIA) to attain CRM and profit maximization and this analytical method can be used by any customer-oriented firm as a general model.

• 천문학회지
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• 제49권3호
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• pp.109-122
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• 2016

[Fe II] emission lines are prominent in the infrared (IR) and important as diagnostic tools for radiative atomic shocks. We investigate the emission characteristics of [Fe II] lines using a shock code developed by Raymond (1979) with updated atomic parameters. We first review general characteristics of the IR [Fe II] emission lines from shocked gas, and derive their fluxes as a function of shock speed and ambient density. We have compiled available IR [Fe II] line observations of interstellar shocks and compare them to the ratios predicted from our model. The sample includes both young and old supernova remnants in the Galaxy and the Large Magellanic Cloud and several Herbig-Haro objects. We find that the observed ratios of the IR [Fe II] lines generally fall on our grid of shock models, but the ratios of some mid-IR lines, e.g., [Fe II] 35.35 µm/[Fe II] 25.99 µm, [Fe II] 5.340 µm/[Fe II] 25.99 µm, and [Fe II] 5.340 µm/[Fe II] 17.94 µm, are significantly offset from our model grid. We discuss possible explanations and conclude that while uncertainties in the shock modeling and the observations certainly exist, the uncertainty in atomic rates appears to be the major source of discrepancy.

• 패션비즈니스
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• 제2권1호
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• pp.49-56
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• 1998

This study is on the fashion design of velve, concentrating on the kinds and the images of it. The velvet, the pile fabrics, includes velveteen, velour(s), corduroy and plush. Ancient Chinese invented it first but Westerners used it widely in fashion since 14C because of the deep colors and the glimmering lights. In 20C the developments of textile industry, the mass production and the dyeing techniques made it popularized as velvet fashion. The velvet must be handled carefully and stretch velvet in vogue today needs the different pattern design and the dressmaking from general fabrics. 'For example, 55 size (bust girth 33", waist girth 26", hip girth 36") Jacket for ladies of stretch velvet, 3/4"ease in the bust line is eliminated at the back on the block pattern after normal pattern design. The costume of velvet has the images of elegance, nostalgia, and oriental ism. It has established the high quality, rich and refined elegance of Haute Couture. It could express the image of nostalgia, the longing for the past with the remarkable splendor. The orientalism of velvet costumes has represented the westerner's aspiration and imagination about the Orient with the intense color and over-decoration.

• 해양환경안전학회지
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• 제7권2호
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• pp.39-48
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• 2001

In recent years, the marine traffic congestion has increased due to the expansion of vessel traffic volume in Korean coastal waterway. Heavy traffic could bring serious marine casualties which cause the loss of human lives, properties and marine pollution in coastal area. The prevention of marine accidents has been a major topic in marin society and various policies and countermeasures have been developed, applied to the industries. VTS(Vessel Traffic Services) is considered as one of effective method to promote marine safety but it needs relatively huge amount of budgets to build and also number of personnels for the operation. Thus prior to establishing the VTS. It should be surveyed the marine traffics, general conditions of waterway including geographical, meteorological characteristics and assessed to find the most reasonable area and places for the system. Therefore this paper aims to develop the method for this evaluation through the hierarchical evaluation structure model in connection with ISM(interpretive structural modeling) and AHP(analytic hierarchy process) methods. The model in this paper is applied to 4 coastal area in Korean waterway as candidates and found that the priority for the needs of VTS should be in order such as Yosu, Wando, Mokpo, Geoje coastal area.