• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.315-319
• /
• 2015

We consider a late decaying dark matter model in which cold dark matter begins to decay into relativistic particles at a recent epoch ($z{\leqslant}1$). A complete set of Boltzmann equations for dark matter and other relevant particles particles is derived, which is necessary to calculate the evolution of the energy density and density perturbations. We show that the large entropy production and associated bulk viscosity from such decays leads to a recently accelerating cosmology consistent with observations. We determine the constraints on the decaying dark matter model with bulk viscosity by using a MCMC method combined with observational data of the CMB and type Ia supernovae.

• Journal of the Korean Chemical Society
• /
• v.40 no.6
• /
• pp.409-414
• /
• 1996

The limit of applicability of Navier-Stokes equation to stationary plane shock-waves is examined by using the principle of minimum entropy production of linear irreversible thermodynamics. In order to obtain analytic results, the equation is linearized near the equilibrium of downstream. Results show that the solution of Navier-Stokes equation which fits the boundary condition of far downstream flow is consistent with the thermodynamic requirement within the first order when the solution is expanded around the M=1, where M is the Mach number of upstream speed.

• Journal of Korean Society of Transportation
• /
• v.17 no.5
• /
• pp.99-110
• /
• 1999

This study deals with the adaptability questions of O-D table estimation models. Its objectives are two-fold; (1) to estimate the characteristics of various O-D table estimation models(i.e. linear regression models. entropy models and statistic models) and (2) to find the model which estimates the O-D table with the best accuracy under the various data conditions. In Pursuing the above, this study gives the particular attentions to the test of the models, using the Sioux Falls network and equilibrium assignment method of MINUTP. The major findings are the followings. Firstly. it finds that the statistic models have the most goodness of fat among all models, if the required data are all Prepared. But it Presents that statistic models are the most sensitive against the underspecification and inconsistency problems of link data. Secondly, It shows that the linear regression models have the worst goodness of fat among all models. But the linear regression models are the most insensitive to the underspecification and inconsistency problems. Thirdly, THE/1 model of entropy model is sensitive against the underspecification and incon-sistency problems, but THE/2 model is insensitive. Finally, other informations like total volume, zonal Production and attraction volumes in 0-D table, help models to gain the better goodness of fit. Especially, in the statistic models. both the zonal production and attraction volume data are helpful to estimate the link volumes. It can be expected that the results dive some implications not only to the selection of optimal model under the various given data, but also to the development or modification of model.

• Archives of design research
• /
• v.17 no.2
• /
• pp.67-76
• /
• 2004

The main stream of consumption about the products is tend to transfer from low price value with mass production, to the second value of products, such as pleasure, familiarity, humor, and metaphor. This second value is closely connected to a redundancy which are also related to modern science as well as product design. These terms such as matrials, identity, and gravitation, disappeared gradually, and these are substituted with an uncertainty principle, a fortuity, a contradictory concept, entropy etc. In sum this study focuses on the tendency of intelligency issue the recent design trends. This result shows that The 4th Column Thinking and Formation System which is related to an expansion and diversity of design intellectual ideas.

• Journal of Korea Multimedia Society
• /
• v.20 no.12
• /
• pp.1992-1999
• /
• 2017

This study proposes a decorative typeface which is produced through the concept of trigonometric functions in an open-source programming language known as Processing. First, the theoretical background of Processing and trigonometric functions as well as previous research in this area are analyzed. Second, basic modules of 'V', 'I', 'O', and 'M' were created for use as the final alphabet typeface with the concept of a trigonometric function. Third, a decorative parabolic curve that encircles the base module was created. Finally, the modules created on Processing were edited in Adobe Illustrator to create a typeface set with characters from A to Z. Various artworks using Programming can produce an infinite number of different versions by modifying only some of the variables and codes, and this method can include multimedia features such as text, images, videos, interactive art and various forms of content and media. Therefore, with regard to expression, the possibilities are endless. In this study, I attempt to expand the field of visual culture using programming and computational methodologies. In contrast to the digital typeface production method, which relies on existing graphic tools, this study is meaningful because it expands the range of use of decorative typefaces.

• Journal of the Korean Chemical Society
• /
• v.68 no.2
• /
• pp.82-86
• /
• 2024

This paper presents the solid-state synthesis of insoluble Prussian blue (Fe₄[Fe(CN)₆]₃·xH₂O, PB) in a ball mill, utilizing the fundamental components of PB. Solid-state synthesis offers several advantages, such as being solvent-free, quantitative, and easily scalable for industrial production. Traditionally, the solid-state synthesis of PB has been limited to the reaction between iron(II/III) ions and hexacyanoferrate(II/III) complex ions, essentially an extension of the solution-based coprecipitation method to solid-state reaction. Taking a bottom-up approach, a reaction is designed where the reactants consist of the basic building blocks of PB: Fe²⁺ ions and CN^- ions. The reaction, with a molar ratio of Fe²⁺ and CN^- corresponding to 1:2.8, yields PB, while a ratio of 1:6.6 results in a mixture of potassium hexacyanoferrate(II) (K₄Fe(CN)₆), potassium chloride (KCl), and potassium cyanide (KCN). This synthetic approach holds promise for environmentally friendly methods to synthesize multimetallic PB with maximum entropy in nearly quantitative yield.

• Journal of Ecology and Environment
• /
• v.43 no.4
• /
• pp.427-437
• /
• 2019

Background: Climate change is believed to be continuously affecting ticks by influencing their habitat suitability. However, we attempted to model the climate change-induced impacts on future genus Rhipicephalus distribution considering the major environmental factors that would influence the tick. Therefore, 50 tick occuance points were taken to model the potential distribution using maximum entropy (MaxEnt) software and 19 climatic variables, taking into account the ability for future climatic change under representative concentration pathways (RCPs) 4.5 and 8.5, were used. Results: MaxEnt model performance was tested and found with the AUC value of 0.99 which indicates excellent goodness-of-fit and predictive accuracy. Current models predict increased temperatures, both in the mid and end terms together with possible changes of other climatic factors like precipitation which may lead to higher tick-borne disease risks associated with expansion of the range of the targeted tick distribution. Distribution maps were constructed for the current, 2050, and 2070 for the two greenhouse gas scenarios and the most dramatic scenario; RCP 8.5 produced the highest increase probable distribution range. Conclusions: The future potential distribution of the genus Rhipicephalus show potential expansion to the new areas due to the future climatic suitability increase. These results indicate that the genus population of the targeted tick could emerge in areas in which they are currently lacking; increased incidence of tick-borne diseases poses further risk which can affect cattle production and productivity, thereby affecting the livelihood of smallholding farmers. Therefore, it is recommended to implement climate change adaptation practices to minimize the impacts.

• Journal of the Society of Naval Architects of Korea
• /
• v.47 no.5
• /
• pp.733-742
• /
• 2010

In this study, optimization was performed to improve the conventional liquefaction process of offshore plants, such as a LNG-FPSO(Liquefied Natural Gas-Floating, Production, Storage, and Offloading unit) by maximizing the energy efficiency of the process. The major equipments of the liquefaction process are compressors, expanders, and heat exchangers. These are connected by stream which has some thermodynamic properties, such as the temperature, pressure, enthalpy or specific volume, and entropy. For this, a process design problem for the liquefaction process of offshore plants was mathematically formulated as an optimization problem. The minimization of the total energy requirement of the liquefaction process was used as an objective function. Governing equations and other equations derived from thermodynamic laws acted as constraints. To solve this problem, the sequential quadratic programming(SQP) method was used. To evaluate the proposed method in this study, it was applied to the natural gas liquefaction process of the LNG-FPSO. The result showed that the proposed method could present the improved liquefaction process minimizing the total energy requirement as compared to conventional process.