• Transactions of the Korean hydrogen and new energy society
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• v.21 no.5
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• pp.375-382
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• 2010

A layered perovskite photocatalysts, $SrBi_2Nb_2O_9$ (SBN), was synthesized by the conventional solid-state reaction method and characterized by X-ray diffraction (XRD) and UV-visble spectrophotometry. The results showed that the structure of $SrBi_2Nb_2O_9$ is orthorhombic. Diffuse reflectance spectra for calcined and attrition-milled SBN showed the main absorption edges were less 400 nm, that is ultraviolet region. SBN under micron-sized powder was deposited on the $Al_2O_3$ by room temperature powder spray in vacuum process, so called aerosol deposition (AD), and nano-grained $SrBi_2Nb_2O_9$ photocatalytic thick film was fabricated. AD-deposited SBN thick films were characterized by XRD, scanning electron microscopy (SEM) and UV-visable spectrophotometry, Moreover, it was found that several nano-sized SBN film by AD process can improve the photocatalytic activity under visable reflectance.

• Korean Institute of Interior Design Journal
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• v.21 no.3
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• pp.95-102
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• 2012

The purpose of this study is to analyze characteristics of residential architecture designed by Gwathmey Siegel in terms of their way of composing spaces and forms. Charles Gwathmey, one of the founders of Gwathmey Siegel, is a worldly famous architect who actively developed Neo-Modernistic architecture in his career. For this study, 15 major houses designed by Gwathmey Siegel were selected and analyzed in terms of their approaches on how to compose various spaces and forms, and how these approaches evolved as time passed. The analysis was mainly based on the drawings and photos of the houses published. The main characteristics found in this study can be summarized as follows: elevated LDK level, split-level composition, use of framing structure, layered space, and linear galleries as a spine of circulation with collaged volumes attached. It turned out these characteristics appeared, faded away, or evolved affecting each other. In early days, Gwathmey often elevated LDK level from ground level for providing privacy, views, and also for separating private rooms. Soon they composed spaces by splitting levels. It not only helped provide privacy where needed effectively, but made space composition more interesting. As sizes of the houses they designed grew, Gwathmey came up with the framing idea for expressing his original architectural language in larger scale. With the split-level composition, the framing method represented Gwathmey's in 70's. This framing introduced layers of interior spaces, and the layers started to break down the monumental framing into individual volumes by bringing in linear spine of circulation. These characteristics helped Gwathmey Siegel develop their own architectural language.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.9
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• pp.750-758
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• 2013

In this paper, we introduce the low-density parity-check (LDPC) coded orthogonal frequency division multiplexing (OFDM) subframe reordering scheme for achieving equal combined power allocation in type I hybrid automatic repeat request (H-ARQ) systems and analyze the performance improvement by using the channel capacity. Also, it is confirmed that the layered decoding for subframe reordering scheme in H-ARQ systems gives faster convergence speed. It is verified from numerical analysis that a subframe reordering pattern having larger channel capacity shows better bit error rate (BER) performance. Therefore the subframe reordering pattern achieving equal combined power allocation for each subframe maximizes the channel capacity and outperforms other subframe reordering patterns. Also, it is shown that the subframe reordering scheme for achieving equal combined power allocation gives better performance than the conventional Chase combining scheme without increasing the decoding complexity.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1197-1199
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• 1993

The molecular electronic devices of organic materials are of current interest. Langmuir-Blodgett(LB) method is the most possible candidate for the development of the molecular electronic devices. One of the critical problems for applications of the LB films to the commercial products will be an electrical conductivity within a LB film. We studied the monolayer characteristics and electrical conductivity of the 1:1 mixture LB films of N-docosylquinolium-TCNQ and $TCNQ^0$. There were some differences in the $\pi-A$ isotherm and UV-visible absorption spectrum of N-docosylquinolium-TCNQ and 1:1 mixture. The small critical area of the $\pi-A$ isotherm for 1:1 mixture may result from the bilayer formation. We confirmed the incorporation of the $TCNQ^0$ with the N-docosylquinolium-TCNQ from the UV-visible absorption spectrum. But the electrical conductivity measured was $10^{-7}$ S/cm for the 1:1 mixture film layered at the surface pressure of 35 mN/m. We couldn't gain any electrical conductivity by mixing the $TCNQ^0$ into the N-docosylquinolium-TCNQ layer. We supposed that $TCNQ^0$ mixed in was not packed parallel to the TCNQ anion radical faces.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.296-296
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• 2007

Ferroelectric neodymium-substituted $Bi_4Ti_3O_{12}$(BTO) thin films have been successfully deposited on Pt/Ti/$SiO_2$/Si substrate by a sol-gel spin-coating process and the effect of crystallization temperature on their microstructure and ferroelectric properties were studied systematically. $Bi(TMHD)_3$, $Nd(TMHD)_3$, $Ti(O^iPr)_4$ were used as the precursors, which were dissolved in 2-methoxyethanol. The thin films were annealed at various temperatures from 600 to $720^{\circ}C$ in oxygen ambient for 1 hr, which was followed by post-annealed for 1 hr after depositing a Pt electrode to enhance the electrical properties. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the crystallinity and surface morphology of layered perovskite phase, respectively. The crystallinity of the BNT films was improved and the average grain size increased as the crystallization temperature increased from 600 to $720^{\circ}C$ at an interval of $40^{\circ}C$. The polarization values of the films were a monotonous function of the crystallization temperature. The remanent polarization value of the BNT thin films annealed at $720^{\circ}C$ was $24.82\;{\mu}C/cm^2$ at an applied voltage of 5 V.

• International Journal of Highway Engineering
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• v.1 no.2
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• pp.155-168
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• 1999

Asphalt pavement tends to rut in high temperature and to crack in cold temperature. The performance of asphalt pavement can be deteriorated by korean weather condition which has the four distinct seasons. In this study, the typical sections that may minimize rutting and fatigue were analyzed through the numerical model tests. The layered elastic theory , finite element method and visco elastic theory were utilized for these numerical model tests. From the various numerical model tests, it is found that an optimum design procedure was recommended. It was increasing the thickness of asphalt stabilized base with fixing the wearing course as 5cm the minimum specified thickness. The section was most beneficial in resting rutting and fatigue. From the analysis of the relative index on tensile strain and cost analysis, it was recommended that the thickness ratio of subbase and asphalt concrete is 1.0$\sim$2.5.

• Korean Journal of Medicinal Crop Science
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• v.25 no.4
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• pp.238-243
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• 2017

Background: The production method of ginseng seedlings for ginseng cultivation is very important to ensure healthy rooting system as well as high quality, and yield of the resultant plants. This study was carried out to compare the growth characteristics of 2-year-old ginseng plants that were produced from seedlings grown in self soil nursery (SSN), nursery soil (NS) or hydroponic culture (HC). Methods and Results: The shading prop used was composed of four-layered 4 polyethylene (blue 3 + black 1) shade screen. The management of main field was done by inserting oil cake (1,200 kg/10 a) and then allowing Sudan grass to grow for a year. Seedling transplantation was carried out on April 6. Root growth was measured on October 25. Root weight was observed to be excellent at 6.0 g, following SSN transplantation. Root length was 21.2 cm for HC seedlings, but these plants had a physiological disorder (i.e., rusty root), in 83.5% plants of this treatment. The ratio of PD/PT (protopanaxadiol saponins / protopanaxatriol saponins) was higher in NS seedlings. Plant analysis revealed that Fe content was lower in HC seedlings with high rustiness. The growth of 2-years-old ginseng was different following these varying seedling cultivation methods, but seedlings from NS were not different from those grown in SSN. Conclusions: For the propagation of 2-year-old ginseng plants, NS seedlings may be a good substitute for SSN seedlings.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.677-683
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• 2000

Three- and five-layer 3Y-YZP/12Ce- TZP composites prepared by a slip casting method have been char­acterized in terms of mechanical properties. The fracture strength of mutilayer c$\alpha$nposites determined in a diametral compression test was 327~534 MPa. Although the indentation strength of the materials was generally reduced with i increasing Vickers indentation load up to 300 N, the damage resistance of multilayer composites was superior com­pared to monolithic layer TZP material. The four-point bend strength of the layered material remained at the values of 620~674 MPa after indentation with a load of 49 N, while that of the monolithic TZP material was 129~339 MPa. The microindentation toughness of the multilayer material was $7.7~13.1\;MPa{\cdot}m^{1/2}$.

• Journal of the Korean Magnetics Society
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• v.25 no.5
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• pp.139-143
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• 2015

The surface magnetism of the CsCl structured Co binary compounds, CoX (X = Ti, V, Nb) (001) surface was studied with the calculated electronic structure data obtained by the full-potential linearized augmented plane-wave (FLAPW) method. The magnetic moment of the surface Co atom of the Co-terminated CoTi(001) system was $1.19{\mu}_B$, which is enhanced compared with that of the Co atom in the center layer. The magnetic moment of the surface V atom in the V terminated the CoV(001) system was $1.64{\mu}_B$, which is more than twice of the center layered V atom. The magnetic moment of surface Co atom in the Co terminated CoV(001) system has the value of $1.34{\mu}_B$, little bit smaller than the bulk value. The magnetism was disappeared in the Co terminated CoNb(001) system, and the magnetic moment of the surface Nb atom in the Nb terminated CoNb(001) system was $0.26{\mu}_B$ which is little bit decreased compared to the center layer value.

• Membrane Journal
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• v.29 no.3
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• pp.130-139
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• 2019

Various two-dimensional nano materials such as graphene, zeolite, and metal-organic framework have been utilized to develop an ultra-thin high-performance membrane for water purification, gas separation, and so on. Particularly, in the case of graphene oxide, synthesis methods and thin film coating techniques have been accumulated and established since early 2000s, therefore graphene oxide has been rapidly applied to membrane field. The multi-layered graphene oxide thin film can filter molecules separately by the molecular sieving of interlayer spacing between adjacent layers, and it is also possible to separate various materials depending on the surface functional groups or the degree of interaction to intercalated materials. This review mainly focuses on the nanofiltration application of graphene oxide. The major factors affecting the separation performance of graphene oxide membrane in solvent are summarized and other technical elements required for the commercialization of graphene oxide membranes will be discussed including stability issue and fabrication method.