• Journal of Photoscience
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• v.11 no.3
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• pp.133-139
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• 2004

The metal-ligand complex, $[Ru(phen)_2(dppz)]^{2+}$ (phen=1,10-phenanthroline, dppz=dipyrido[3,2-a:2',3'-c]phenazine) (RuPD), was used as a spectroscopic probe for studying nucleic acid dynamics. The RuPD complex displays a long lifetime and a molecular light switch property upon DNA binding due to shielding of its dppz ligand from water. To show the usefulness of this luminophore (RuPD) for probing nucleic acid dynamics, we compared its intensity and anisotropy decays when intercalated into the $tRNA^{val}$ and pBluescript (pBS) II SK(+) phagemid through a comparison with ethidium bromide (EB), a conventional nucleic acid probe. We used frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The mean lifetime for the $tRNA^{val}$ (<${\tau}$> = 166.5 ns) was much shorter than that for the pBS II SK(+) phagemid (<${\tau}$> = 481.3 ns), suggesting a much more efficient shielding from water by the phagemid. Because of their size difference, the anisotropy decay data showed a much shorter rotational correlation times for the $tRNA^{val}$ (99.9 and 23.6 ns) than for the pBS II SK(+) phagemid (968.7 and 39.5 ns). These results indicate that RuPD can be useful for studying nucleic acid dynamics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.617-631
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• 2019

In the four-step demand model, a gravity mode is used most commonly at the trip distribution stage. The purpose of this study was to develop a new friction factor that can express the accessibility property as a single friction factor to compensate for the variable limits of the gravity model parameters (travel time, travel cost). To derive a new friction factor, a new friction factor was derived using the space syntax that can quantify the characteristics of the urban space structure, deriving the link-unit integration degree and then using the travel time and travel distance relationship. Calibration of the derived friction factor resulted in a similar level to that of the existing friction factor. As a result of verifying the various indicators, the explanatory power was found to be excellent in the short - and long - distance range. Therefore, it is possible to derive and apply the new friction factor using the integration index, which can complement the accessibility beyond the limit of the existing shortest distance, and it is believed to be more advantageous in future utilization.

• Korean Chemical Engineering Research
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• v.47 no.2
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• pp.150-156
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• 2009

Plasma Display Panels(PDPs) require to have improved luminous efficiency, low manufacturing cost, and high image quality to compete with other flat display devices such as Liquid Crystal Displays(LCDs) and organic light-emitting diodes(OLEDs). In addition, the diversity of product line-up may be needed for high market share. In this paper, the optical characteristics of typical green phosphor for PDP application are reviewed and the problem-based solution will be proposed. We also shortly describe the principle of 3D-PDPs which are promising. Then, the requirement of green phosphor for 3D-PDP application is summarized and research achievement, as of now, is described. The typical problems of $Zn_2SiO_4:Mn$ phosphor, which is the most well-known, are the negatively charged surface property and the long decay time, which leads to unstable discharge in green cell and afterimage. These problems were solved by coating the phosphor surface with metallic oxide. It was found that $Al_2O_3$ would be the best material for $Zn_2SiO_4:Mn$ phosphor. It gives longevity as well as low operating voltage due to the charging effect in green cells. Also, new phosphors, $(Y,\;Gd)Al_3(BO_3)_4:Tb$ and $(Mg,\;Zn)Al_2O_4:Mn$ phosphor are proposed for increasing the luminance and reducing the decay time, which are capable to apply for 3D-PDP application.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.71-77
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• 2014

Despite the ubiquity of electronic media, paper is still the most generally readable carrier of information. Because paper materials are deteriorated by chemical, biological and physical factors over time, there have been major concerns about the decay of large collections of books, publications, old maps, historical artifacts, and written records. Therefore, manufacture of permanent paper has been a highly debated issue in paper conservation research. Through the use of permanent paper, our new records, journals, library books, art works, and all culturally and historically important documents can be preserved. In this study, handsheets were made of mixture of hemp bast fiber produced by soda pulping and HwBKP varying the amount of hemp. Physical, mechanical and optical properties of each handsheet were examined. As the ratio of hemp bast fiber increased, mechanical properties were improved significantly, but opacity decreased. After aging, the optical properties of the handsheets mixed with the hemp bast fiber more decreased than those of the non-mixed handsheet. The more mixture ratio of hemp bast fiber increased, the more decreasing rate of optical properties increased. As a result, it was confirmed that hemp bast fiber is a very promising resource for the manufacturing of permanent paper.

• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.41-50
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• 2000

Cement-bonded particleboard is being used as outdoor siding material all over the world, because this composite particularly bears a light weight, high resistance against fire, decay, and crack by cyclic freezing and thawing, anti-shock property, and strength enhancement. Construction systems are currently changing into a frame-building style and wooden houses are being constructed with prefabrication type. Therefore, they require a more durability at outdoor-exposed sides. In this study, the cement hydration property for Korean pine particle, Japanese larch particle and face- and middle layer particles (designated as PB particle below) used in Korean particleboard-manufacturing company was investigated, and the rapid manufacturing characteristics of cement-bonded particleboard by supercritical $CO_2$ curing was evaluated. Korean pine flour showed a good hydration property, however, larch flour showed a bad one. PB particle had a better hydration property than larch flour. The addition of $Na_2SiO_3$ indicated a negative effect on hydration, however, $MgCl_2$ had a positive one. Curing by supercritical $CO_2$ fluid gave a conspicuous enhancement in the performances of cement-bonded particleboards compared to conventional curing. $MgCl_2$ 3%-added PB particle had the highest properties, and $MgCl_2$ 1%-added Korean pine particle had the second class with the conditions of cement/wood ratio of 2.7, a small fraction-screened particle and supercritical curing. On the contrary, the composition of non-hammermilled or large fraction-screened particle at cement/wood ratio of 2.2 was poorer. Also, the feasibility for actual use of 3%-added, small PB particle-screened fraction was greatest of all the conventional curing treatments. Relative superiority of supercritical curing vs. conventional curing at dimensional stability was not so apparent as in strength properties. Through the thermogravimetric analysis, it was ascertained that the peak of a component $CaCO_3$ was highest, and the two weak peaks of calcium silicate hydrate and ettringite and $Ca(OH)_2$ were present in supercritical treatment. Accordingly, it was inferred that the increased formation of carbonates in board contributes to strength enhancement.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.1963-1973
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• 2020

Liquid metal-cooled reactors use various passive safety systems driven by natural circulation. Investigating these safety systems experimentally is more advantageous by using a simulant. Although numerous experimental approaches have been applied to natural circulation-driven passive safety systems using simulants, there has been no clear validation of the similarity law. To validate the similarity law experimentally, SINCRO-V experiment was conducted using Wood's metal and water for simulant of the Wood's metal. A pair of SINCRO-V facilities with length-scale ratio of 14.1:1 for identical Bo' was investigated, which was the main similarity parameter in temperature field simulation. In the experimental range of 0.2-1.0% of decay heat, the temperature distribution characteristics of the small water facility were very similar to that of the large Wood's metal facility. The temperature of the Wood's metal predicted by the water experiment showed good agreement with the actual Wood's metal temperature. Despite some error factors like discordance of Gr' and property change along the temperature, the water experiment predicted the Wood's metal temperature with an error of 27%. The validity of the similarity law was confirmed by the SINCRO-V experiments.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.78-78
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• 2015

Metamaterials, artificially structured nanomaterials, have enabled unprecedented phenomena such as invisibility cloaking and negative refraction. Especially, hyperbolic metamaterials also known as indefinite metamaterials have unique dispersion relation where the principal components of its permittivity tensors are not all with the same signs and magnitudes. Such extraordinary dispersion relation results in hyperbolic dispersion relations which lead to a number of interesting phenomena, such as super-resolution effect which transfers evanescent waves to propagating waves at its interface with normal materials and, the propagation of electromagnetic waves with very large wavevectors comparing they are evanescent waves and thus decay quickly in natural materials. In this abstract, I will focus discussing our efforts in achieving the unique optical property overcoming diffraction limit to achieve several extraordinary metamaterials and metadevices demonstration. First, I will present super-resolution imaging device called "hyperlens", which is the first experimental demonstration of near- to far-field imaging at visible light with resolution beyond the diffraction limit in two lateral dimensions. Second, I will show another unique application of metamaterials for miniaturizing optical cavity, a key component to make lasers, into the nanoscale for the first time. It shows the cavity array which successfully captured light in 20nm dimension and show very high figure of merit experimentally. Last, I will discuss the future direction of the hyperbolic metamaterial and outlook for the practical applications. I believe our efforts in sub-wavelength metamaterials having such extraordinary optical properties will lead to further advanced nanophotonics and nanooptics research.

• Applied Biological Chemistry
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• v.32 no.4
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• pp.332-337
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• 1989

Rheological properties of rehydrated freeze dried instant rice were investigated in comparison with that of cooked rice. The time changes in reciprocal hardness of instant rice grains at various rehydration temperatures$(60{\sim}90^{\circ}C)$ could be expressed by the first order reaction rate equation regardless of rehydration temperature and reaction rate constant increased as the rehydration temperature increased. Activation energy for rehydrating instant rice was 6.1 kcal/g-mol. Analysis of compressive stress relaxation test showed that the viscoelastic properties of both rehydrated instant rice and cooked rice grains could be expressed by 6-elements generalized Maxwell model. Rehydrated instant rice revealed higher relaxation decay than that of cooked rice and showed the elastic property increased by increasing the rehydration temperature.

• Journal of the Korean housing association
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• v.24 no.4
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• pp.53-60
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• 2013

Apartments amount to 58.3%, the highest proportion of domestic housing types. These apartments' lifespan (approximately 27 years) are one-third of the developed countries' housing lifespan due to the property developers and mass production. It is significantly short-cycle period considering the original physical lifespan of the apartment housing are 60 years. It has caused economic loss and environmental degradation. In recent years, research and development for the long life of the apartment housing has been actively performed, but it is limited on reconstruction and new construction. Reconstruction of existing a number of high-rise apartments is difficult owing to restrictions on the floor area ratio allowing for 40 years limit of decay resistance after the completion. Improving lifespan of the building has recently begun to receive attention as an alternative to remodeling. However, These sort of remodeling techniques tend to be focused on technology developed for the physical life extension. That means developing the techniques about dwelling-unit environment for residents satisfaction are required as well as improving physical construction. The purpose of this study is to propose and verify the Participatory Design Technique which can help the residents as the active participation in the design decision-making process.

• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
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• 2003.09a
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• pp.6-6
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• 2003

In this work we consider the mathematical formulation and numerical resolution of the linear feedback control problem for Boussinesq equations. The controlled Boussinesq equations is given by $$\frac{{\partial}u}{{\partial}t}-{\nu}{\Delta}u+(u{\cdot}{\nabla}u+{\nabla}p={\beta}{\theta}g+f+F\;\;in\;(0,\;T){\times}\;{\Omega}$$, $${\nabla}{\cdot}u=0\;\;in\;(0,\;T){\times}{\Omega}$$, $$u|_{{\partial}{\Omega}=0,\;u(0,x)=\;u_0(x)$$ $$\frac{{\partial}{\theta}}{{\partial}t}-k{\Delta}{\theta}+(u{\cdot}){\theta}={\tau}+T,\;\;in(0,\;T){\times}{\Omega}$$ $${\theta}|_{{\partial}{\Omega}=0,\;\;{\theta}(0,X)={\theta}_0(X)$$, where $\Omega$ is a bounded open set in $R^{n}$, n=2 or 3 with a $C^{\infty}$ boundary ${\partial}{\Omega}$. The control is achieved by means of a linear feedback law relating the body forces to the velocity and temperature field, i.e., $$f=-{\gamma}_1(u-U),\;\;{\tau}=-{\gamma}_2({\theta}-{\Theta}}$$ where (U,$\Theta$) are target velocity and temperature. We show that the unsteady solutions to Boussinesq equations are stabilizable by internal controllers with exponential decaying property. In order to compute (approximations to) solution, semi discrete-in-time and full space-time discrete approximations are also studied. We prove that the difference between the solution of the discrete problem and the target solution decay to zero exponentially for sufficiently small time step.