• Journal of Photoscience
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• 제11권3호
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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.

• 한국산학기술학회논문지
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• 제20권3호
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• pp.617-631
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• 2019

본 4단계 교통수요예측모형의 통행분포단계에서 중력모형이 가장 일반적으로 활용하고 있다. 본 연구는 중력모형변수(통행시간, 통행비용 등)의 가변적인 한계를 보완하기 위해 접근성 속성을 단일 마찰인자로서 표현할 수 있는 보다 현실적이고 장래 활용이 용이한 신규 마찰인자를 개발하는데 그 목적이 있다. 이에 신규 마찰인자 도출을 위해 도시공간구조의 특성을 정량화할 수 있는 공간구문론(space syntax)을 활용하여 Link 단위 통합도를 도출 후 통행시간, 통행거리 관계를 이용해 일종의 대리변수로서의 신규 마찰인자를 도출하였다. 대수전환을 통한 마찰인자별 정산결과, 기존 마찰인자(최단거리, 통행시간) 대비 유사하거나 더 높은 수준을 보이는 것으로 분석되었다. 다양한, 검증지표를 활용하여 기존 마찰인자와의 비교시, 전체적으로는 기존 마찰인자와 유사하지만, 단거리 구간 및 장거리 구간에서 설명력이 뛰어난 것으로 분석되었다. 따라서, 기존 최단거리의 한계에서 벗어나 접근성을 보완할 수 있는 통합도 지표를 이용하여 신규마찰인자 도출 및 적용이 가능하고, 장래 활용성에서 좀 더 장점을 갖는 것으로 판단된다.

• Korean Chemical Engineering Research
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• 제47권2호
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• pp.150-156
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• 2009

플라즈마 디스플레이 패널(Plasma Display Panel; PDP)이 Liquid Crystal Display(LCD) 등 다른 대형 평면 디스플레이 분야와 경쟁하기 위해선 제품의 다양성과 발광 효율의 향상, 저가격화, 고화질화 등의 기술 발전이 요구된다. 본 논문에서는 우선 기존 PDP용 녹색 형광체의 특성과 문제점, 이를 해결하기 위한 방법에 대해 개괄적으로 논의한다. 또한, 제품의 다양성을 위해 개발 진행 중인 3D-PDP의 원리와 이의 실현을 위한 형광체의 요구 특성에 대해 기술한다. 대표적인 PDP용 녹색 형광체인 $Zn_2SiO_4:Mn$ 형광체가 가진 문제점은 표면의 높은 음전하와 상대적으로 긴 잔광 시간으로 요약된다. 표면의 높은 음전하와 플라즈마의 가혹한 환경에 노출로 인한 열화 현상은 금속 산화물의 코팅을 통해 해결할 수 있음을 알 수 있었으며, 특히 $Al_2O_3$가 코팅되었을 때 가장 큰 효과를 볼 수 있음을 알 수 있었다. 상대적으로 긴 잔광 시간은 Mn 농도를 늘린 $Zn_2SiO_4:Mn$ 형광체를 사용함으로 개선할 수 있고, 부족한 휘도는 $YBO_3:Tb$ 형광체를 혼합하여 사용함으로써 개선할 수 있었다. 아울러 본 연구에서는 $YBO_3:Tb$ 형광체 대신으로 115%의 휘도를 가지는 $(Y,\;Gd)Al_3(BO_3)_4:Tb$ 형광체의 사용이 가능함을 제안하였으며, 3D-PDP에 적용하기에 적합한 1 ms 내외의 잔광 시간을 가지는 $(Mg,\;Zn)Al_2O_4:Mn$ 형광체를 제안하였다.

• 펄프종이기술
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• 제46권6호
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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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• 제28권4호
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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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• 제52권9호
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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.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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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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• 제32권4호
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• pp.332-337
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• 1989

재수화한 동결건조 즉석미반의 리올로지 성질을 통상법으로 취반한 미반과 비교하면서 조사하였다. 온도$(60{\sim}90^{\circ}C)$를 달리한 복원시간에 따른 미립 경도의 역수(연화도)는 복원온도에 상관없이 1차 반응 속도식에 따라 감소하였고, 경도반응의 속도 상수 값은 온도에 따라 증가하였으며, 이의 활성화 에너지는 6.1 kcal/g-mol이었다. 여러 온도 $(60{\sim}90^{\circ}C)$에서 복원시킨 즉석미반의 압축응력 완화 곡선은 통상법으로 취반한 미반과 마찬가지로 일반화된 Maxwell의 6요소 역학모형으로 설명되었고, 즉석미반은 취반미보다 완화되기 쉬우나 복원온도가 높을수록 탄력성이 높아지는 특성을 나타내었다.

• 한국주거학회논문집
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• 제24권4호
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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.

• 한국전산응용수학회:학술대회논문집
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• 한국전산응용수학회 2003년도 KSCAM 학술발표회 프로그램 및 초록집
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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.