• Journal of the Optical Society of Korea
• /
• v.7 no.2
• /
• pp.72-78
• /
• 2003

It is reported that the spectral loss of photonic crystal fiber (PCF) having a large hole-to-hole distance (~ 10 ${\mu}{\textrm}{m}$) is sensitive to micro- and macrobending when compared with the conventional single-mode fiber. In this paper, we will present the measurement result of the macro- and microbending characteristics of fabricated PCF with large hole-to-hole distance (> 10 ${\mu}{\textrm}{m}$) . For the macrobending experiment, the fiber was simply wound around a circular structure with variable diameter that could be reduced to a few centimeters. For the microbending case, regularly spaced silica rods were attached on a slide glass and pressed against the fiber by loading a stack of metal plates of known weight on the glass. The transmission loss spectrum shows a rather flat response to the to microbending, and this makes the PCF a good candidate for a wideband variable optical attenuator.

• Journal of Positioning, Navigation, and Timing
• /
• v.7 no.4
• /
• pp.189-203
• /
• 2018

In this paper, a Software Defined Radio (SDR) architecture was designed and implemented for rapid prototyping of GNSS receiver. The proposed SDR can receive various GNSS and direct sequence spread spectrum (DSSS) signals without software modification by expanded input parameters containing information of the desired signal. Input parameters include code information, center frequency, message format, etc. To receive various signal by parameter controlling, a correlator, a data bit extractor and a receiver channel were designed considering the expanded input parameters. In navigation signal processing, pseudorange was measured based on Coordinated Universal Time (UTC) and appropriate navigation message decoder was selected by message format of input parameter so that receiver position can be calculated even if SDR is set up various GNSS combination. To validate the proposed SDR, the software was implemented using C++, CUDA C based on GPU and USRP. Experimentation has confirmed that changing the input parameters allows GPS, GLONASS, and BDS satellite signals to be received. The precision of the position from implemented SDR were measured below 5 m (Circular Error Probability; CEP) for all scenarios. This means that the implemented SDR operated normally. The implemented SDR will be used in a variety of fields by allowing prototyping of various GNSS signal only by changing input parameters.

• Journal of Korean Association for Spatial Structures
• /
• v.20 no.4
• /
• pp.63-71
• /
• 2020

The fluctuating wind pressure of the low rise ratio(f/D=0.1) for the elliptical dome roof was analyzed to compare it with the previous studies of circular dome roofs. Wind tunnel test were conducted on a total of 10 wind directions from 0° to 90° while changing wall height-span ratios(H/D=0.1-0.5). For this, meanCP, rmsCP and wind pressure spectrum were analyzed. The analysis result leads to find differences in the shape of the spectra in the spanwise direction and leeward of the elliptical dome according to the wind direction variations of the elliptical dome roof.

• Structural Engineering and Mechanics
• /
• v.87 no.4
• /
• pp.347-361
• /
• 2023

This research aims to assess the behavior of reinforced concrete (RC) residential buildings when moment-resisting frames (MRFs) are used as the lateral resisting system. This investigation was conducted using MIDAS Gen v.19.0. Buildings with various plan footprints (Square, Rectangular, Circular, Triangular, and Plus-Shaped), and different heights (15 m, 30 m, 45 m, and 60 m) are investigated. The defined load cases, the equivalent static lateral load pattern, and the response spectrum function were defined as stated by the American Standard (ASCE 7-16), the 1997 Uniform Building Code (UBC97), the Egyptian Code for Loads (ECP-201), and the European Standard (EC8). Extensive comparisons of the results obtained by the different codes (including the story displacement, the story drift, and the base shear) were undertaken; to assess the response of moment-resisting multi-story framed buildings under lateral loads. The results revealed that, for all study cases under consideration, both ECP-201 and EC8 gave smaller base shear, displacement, and drift by one third to one fourth, around one fourth, around one fifth, respectively for both the ELF and RSA methods if compared to ASCE 7-16 and UBC97.

• Journal of The Korean Astronomical Society
• /
• v.46 no.3
• /
• pp.125-131
• /
• 2013

We present the relation between the genus in cosmology and the Betti numbers for excursion sets of three- and two-dimensional smooth Gaussian random fields, and numerically investigate the Betti numbers as a function of threshold level. Betti numbers are topological invariants of figures that can be used to distinguish topological spaces. In the case of the excursion sets of a three-dimensional field there are three possibly non-zero Betti numbers; ${\beta}_0$ is the number of connected regions, ${\beta}_1$ is the number of circular holes (i.e., complement of solid tori), and ${\beta}_2$ is the number of three-dimensional voids (i.e., complement of three-dimensional excursion regions). Their sum with alternating signs is the genus of the surface of excursion regions. It is found that each Betti number has a dominant contribution to the genus in a specific threshold range. ${\beta}_0$ dominates the high-threshold part of the genus curve measuring the abundance of high density regions (clusters). ${\beta}_1$ dominates the genus near the median thresholds which measures the topology of negatively curved iso-density surfaces, and ${\beta}_2$ corresponds to the low-threshold part measuring the void abundance. We average the Betti number curves (the Betti numbers as a function of the threshold level) over many realizations of Gaussian fields and find that both the amplitude and shape of the Betti number curves depend on the slope of the power spectrum n in such a way that their shape becomes broader and their amplitude drops less steeply than the genus as n decreases. This behaviour contrasts with the fact that the shape of the genus curve is fixed for all Gaussian fields regardless of the power spectrum. Even though the Gaussian Betti number curves should be calculated for each given power spectrum, we propose to use the Betti numbers for better specification of the topology of large scale structures in the universe.

• Journal of the Korean Chemical Society
• /
• v.37 no.11
• /
• pp.951-960
• /
• 1993

$Hg^{2+}$-induced aquation trans-[Co(3,2,3-tet)$X_2]^+$(3,2,3-tet = 4,7-diazadecane-1,10-diamine, $X_2\;=\;Cl_2,\;(NO_2)Cl,\;Br_2,\;(NO_2)Br,\;(NO_3)_2)$ complexes was investigated in aqueous solution. The products and the reaction mechanism were confirmed by chromatography, UV/Vis. spectrum, and circular dichroism (CD) spectrum. From the results, $Hg^{2+}$-induced aquation of 3,2,3-tet system has been produced cis-${\beta}$ complex via trans complex. The kinetic studies on $Hg^{2+}$-induced aquation of trans-[Co(3,2,3-tet)$Cl_2]^+$ complex and trans-[Co(3,2,3-tet)$(NO_2)Cl]^+$ complex were also carried out to study the reaction mechanism. The results show that trans-[Co(3,2,3-tet)$Cl_2]^+$ complex undergoes the D(dissociative)-mechanism and trans-[Co(3,2,3-tet)$(NO_2)Cl]^+$ complex $I_d$(interchange dissociavite)-mechanism. In order to confirm steric course for the reaction mechanism, $Hg^{2+}$-induced aquation on trans-[Co(R,R-3,2,3-tet)$Cl_2]^+$ complex to which chiral R,R-3,2,3-tet was coordinated instead of the racemic(R,R:S,S) 3,2,3-tet was used has been examined by CD spectrum. From the results, the final complex was confirmed to be ${\Delta}-cis-{\beta}$-[Co(R,R-3,2,3-tet)$(OH_2)_2]^{3+}$ complex indicating the chirality was retained through whole process.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.1C
• /
• pp.1-7
• /
• 2012

At the industrial work site, the manufacturing process is being automated to improve work efficiency. However, it is often difficult to automate the entire manufacturing process, and there are spaces in which workers there are constantly exposed to danger. To protect such workers from the danger, this paper studied a worker safety management system for the industrial work site which uses a location recognition system and which is based on the Ubiquitous-Wireless Sensor Network (U-WSN). Using wireless signals, the distance between two devices can be measured and the location of a worker can be calculated using triangularization in 3-D. But at the industrial work sites where there are a lot of steel and structures, errors occur due to signal reflection and multi-path, etc., which makes it difficult to get the accurate location. To address this problem the following was done: first, a circular polarization patch antenna appropriate to the work site was used to reduce the degree of error that may occur from the antenna emission pattern and the particular Line of Sight (LOS); second, a 3-D localization technique and a filtering algorithm were used to improve the accuracy of location determination. The developed system was tested by using it on a wharf crane to validate its accuracy and effectiveness. The proposed location recognition system is expected to contribute greatly in ensuring the safety of workers at industrial work sites.

• Journal of the Korean Magnetics Society
• /
• v.22 no.4
• /
• pp.125-129
• /
• 2012

By employing soft x-ray absorption spectroscopy (XAS) and soft x-ray magnetic circular dichroism (XMCD), the electronic structures of molecule-based nano bioparticles, such as Helicobacter pylori ferritin (H. pylori ferritin), Heme, $NaM[Fe(CN)_6]{\cdot}H_2O$-type Prussian Blue (M=Co, Ni) analogue, have been investigated. The measured Fe 2p XAS spectra reveal that Fe ions are trivalent ($Fe^{3+}$) in H. pylori ferritins, while they are in the $Fe^{2+}-Fe^{3+}$ mixed-valent states in $NaM[Fe(CN)_6]{\cdot}H_2O$ Prussian Blue analogues (M=Co, Ni). According to the Fe 2p XMCD spectrum of high-state H. pylori ferritin, all the $Fe^{3+}$ ions have the same local symmetry and their magnetic moments are aligned in the same direction. It is also found that the Fe 3d orbitals in $NaM[Fe(CN)_6]{\cdot}H_2O$ have a strong covalent bonding to $(CN)^-$ ligands, but with a very weak bonding to the 2p orbitals of O ligands.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.7
• /
• pp.2117-2124
• /
• 2013

The binding properties and sequence selectivities of ${\Delta}{\Delta}$- and ${\Lambda}{\Lambda}-[{\mu}-Ru_2(phen)_4(bip)]^{4+}$ (bip = 4,4'-biphenylene (imidazo [4,4-f][1,10]phenanthroline) complexes with $poly[d(A-T)_2]$ and $poly[d(G-C)_2]$ were investigated using conventional spectroscopic methods. When bound to $poly[d(A-T)_2]$, a large positive circular dichroism (CD) spectrum was induced in absorption region of the bridging moiety for both the ${\Delta}{\Delta}$- and ${\Lambda}{\Lambda}-[{\mu}-Ru_2(phen)_4(bip)]^{4+}$ complexes, which suggested that the bridging moiety sits in the minor groove of the polynucleotide. As luminescence intensity increased, decay times became longer and complexes were well-protected from the negatively charged iodide quencher compared to that in the absence of $poly[d(A-T)_2]$. These luminescence measurements indicated that Ru(II) enantiomers were in a less polar environment compared to that in water and supported by minor groove binding. An angle of $45^{\circ}$ between the molecular plane of the bridging moiety of the ${\Delta}{\Delta}-[{\mu}-Ru_2(phen)_4(bip)]^{4+}$ complex and the local DNA helix axis calculated from reduced linear dichroism ($LD^r$) spectrum further supported the minor groove binding mode. In the case of ${\Lambda}{\Lambda}-[{\mu}-Ru_2(phen)_4(bip)]^{4+}$ complex, this angle was $55^{\circ}$, suggesting a tilt of DNA stem near the binding site and bridging moiety sit in the minor groove of the $poly[d(A-T)_2]$. In contrast, neither ${\Delta}{\Delta}$-nor ${\Lambda}{\Lambda}-[{\mu}-Ru_2(phen)_4(bip)]^{4+}$ complex produced significant CD or $LD^r$ signal in the absorption region of the bridging moiety. Luminescence measurements revealed that both the ${\Delta}{\Delta}$- and ${\Lambda}{\Lambda}-[{\mu}-Ru_2(phen)_4(bip)]^{4+}$ complexes were partially accessible to the $I^-$ quencher. Furthermore, decay times became shorter when bis-Ru(II) complexes bound to $poly[d(G-C)_2]$. These observations suggest that both the ${\Delta}{\Delta}$- and ${\Lambda}{\Lambda}-[{\mu}-Ru_2(phen)_4(bip)]^{4+}$ complexes bind at the surface of $poly[d(G-C)_2]$, probably electrostatically to phosphate group. The results indicate that ${\Delta}{\Delta}$- and ${\Lambda}{\Lambda}-[{\mu}-Ru_2(phen)_4(bip)]^{4+}$ are able to discriminate between AT and GC base pairs.

• BMB Reports
• /
• v.40 no.2
• /
• pp.163-171
• /
• 2007

Functional elements of the conserved helix 7 in the poreforming domain of the Bacillus thuringiensis Cry $\delta$- endotoxins have not yet been clearly identified. Here, we initially performed alanine substitutions of four highly conserved aromatic residues, $Trp^{243}$, $Phe^{246}$, $Tyr^{249}$ and $Phe^{264}$, in helix 7 of the Cry4Ba mosquito-larvicidal protein. All mutant toxins were overexpressed in Escherichia coli as 130-kDa protoxins at levels comparable to the wild-type. Bioassays against Stegomyia aegypti mosquito larvae revealed that only W243A, Y249A or F264A mutant toxins displayed a dramatic decrease in toxicity. Further mutagenic analysis showed that replacements with an aromatic residue particularly at $Tyr^{249}$ and $Phe^{264}$ still retained the high-level toxin activity. In addition, a nearly complete loss in larvicidal activity was found for Y249L/F264L or F264A/ Y249A double mutants, confirming the involvement in toxicity of both aromatic residues which face towards the same direction. Furthermore, the Y249L/F264L mutant was found to be structurally stable upon toxin solubilisation and trypsin digestion, albeit a small change in the circular dichroism spectrum. Altogether, the present study provides for the first time an insight into the highly conserved aromaticity of $Tyr^{249}$ and $Phe^{264}$ within helix 7 playing an important role in larvicidal activity of the Cry4Ba toxin.