• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.3
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• pp.192-199
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• 2018

This paper proposes an improved discrete Fourier transform spread single sideband(DFT-s-SSB) orthogonal frequency division multiplexing(OFDM) system that solves the problems of conventional DFT-s-SSB OFDM systems. Conventional DFT-s-SSB systems use pulse amplitude modulation(PAM) for applying SSB modulation. The higher the modulation level, the worse is the BER performance. Further, transmission is possible only through the lower sideband(LSB) spectrum. When transmitting using the LSB and upper sideband(USB) spectra simultaneously, interference occurs and spectrum recovery is not performed correctly. To solve this problem, the proposed system applies the 2/3 convolution coding to improve the bit error rate(BER) performance, adjusts the DFT size, and selects the USB spectrum to utilize the remaining spectrum resources. In addition, when using this system in an environment that supports multiuser or limited bandwidth, it uses only half of the spectrum; therefore, it can utilize the remaining spectrum resources and improve the spectral efficiency.

• Journal of Conservation Science
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• v.31 no.3
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• pp.299-308
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• 2015

Aim of this study is to identify dyestuff of the Dallryeong(official's robe in Joseon Dynasty, 16th century) excavated from Yuryang-dong, Cheonan, in 1996. For this purpose, extracted dyestuffs from Dallryeong fabric and from natural dyestuffs for red color(safflower, Sapanwood, Madder) which are presumed to have been used in the Dallryeong, are analyzed and compared by high performance liquid chromatography(HPLC). As a result, HPLC chromatogram of extracts of the Dallryeong's dyestuff and safflower are showed a peak at 17.5 minutes. The UV/Vis spectra of the samples are showed the maximum absorption wavelength at 519nm. This result is identical with the analysis of the previous studies on red dyestuff of safflower. In addition, the analysis of Mass Spectrometry(MS) showed the identical result of the peak with m/z 910. Following these results, excavated pink Dallryeong were considered to have been dyed with safflower.

• Wind and Structures
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• v.26 no.4
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• pp.191-204
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• 2018

This article presents a study of the largest-ever (height = 220 m) cooling tower using the large eddy simulation (LES) method. Information about fluid fields around the tower and 3D aerodynamic time history in full construction process were obtained, and the wind pressure distribution along the entire tower predicted by the developed model was compared with standard curves and measured curves to validate the effectiveness of the simulating method. Based on that, average wind pressure distribution and characteristics of fluid fields in the construction process of ultra-large cooling tower were investigated. The characteristics of fluid fields in full construction process and their working principles were investigated based on wind speeds and vorticities under different construction conditions. Then, time domain characteristics of ultra-large cooling towers in full construction process, including fluctuating wind loads, extreme wind loads, lift and drag coefficients, and relationship of measuring points, were studied and fitting formula of extreme wind load as a function of height was developed based on the nonlinear least square method. Additionally, the frequency domain characteristics of wind loads on the constructing tower, including wind pressure power spectrum at typical measuring points, lift and drag power spectrum, circumferential correlations between typical measuring points, and vertical correlations of lift coefficient and drag coefficient, were analyzed. The results revealed that the random characteristics of fluctuating wind loads, as well as corresponding extreme wind pressure and power spectra curves, varied significantly and in real time with the height of the constructing tower. This study provides references for design of wind loads during construction period of ultra-large cooling towers.

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.348-356
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• 1996

A mobile CARS spectrometer is constructed to measure the instantaneous temperature of gases, of which software include the quick fit methods and a least square fitting method to obtain temperatures from the spectra. Two quick-fit-methods give smaller variance of temperatures than the least square fitting method even though they consume much shorter time to yield temperatures. The precision and accuracy of CARS temperature is measured in the graphite tube blackbody furnace in reference to a radiation pyrometer. The accuracy of the CARS temperature is $\pm$2% from 1000K to 2400K and the precision is $\pm$35K at 1600K with the most accurate quick-fit-method. As a demonstration of the instantaneous measurement, the spectrometer is applied for measurement of the turbulent combustion at a certain condition. eograms(HS) are made using a relatively small number of synthesized 2D images. The influence of aliasing artifacts caused by insufficient or improper sampling is presented, and a new sampling theory is proposed, which is used to making holographic stereograms. Also, the optical system for extension of viewing distance and viewing zone is proposed. Results of this analysis can be applied to design normal holographic stereograms and computer based holographic stereograms.

• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.359-364
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• 2014

We report parameters that allow the dielectric functions ${\varepsilon}={\varepsilon}_1+i{\varepsilon}_2$ of $AlAs_xSb_{1-x}$ alloys to be calculated analytically over the entire composition range $0{\leq}x{\leq}1$ in the spectral energy range from 0.74 to 6.0 eV by using the dielectric function parametric model (DFPM). The ${\varepsilon}$ spectra were obtained previously by spectroscopic ellipsometry for x = 0, 0.119, 0.288, 0.681, 0.829, and 1. The ${\varepsilon}$ data are successfully reconstructed and parameterized by six polynomials in excellent agreement with the data. We can determine ${\varepsilon}$ as a continuous function of As composition and energy over the ranges given above, and ${\varepsilon}$ can be converted to complex refractive indices using a simple relationship. We expect these results to be useful for the design of optoelectronic devices and also for in situ monitoring of AlAsSb film growth.

• BMB Reports
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• v.29 no.5
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• pp.429-435
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• 1996

To investigate the structure-antagonistic relationship of the cyclohexapeptide L-659,877, a selective NK-2 tachykinin receptor antagonist, seven analogues were chemically synthesized by a solid phase method. The agonistic and antagonistic activities of the analogues were evaluated by contraction assay using the smooth muscle of guinea pig trachea (GPT) containing the NK-2 receptor. It was shown that the aromatic ring of Phe at position 3 and the sulfur group of Met at position 6 in L-659,877 were essential for binding to the NK-2 receptor. Decrease in antagonistic activity of L-659,877 caused by substituting Leu for Nle at position 5 indicates that the ${\gamma}$ methyl group and side chain length of Leu plays an important role in its antagonistic action. Although the activity was slightly lower than L-659,877, cyclo $[{\beta}Ala^{8}]NKA(4-10)$ (analogue 1) showed potential antagonistic activity for the NK-2 receptor. It was confirmed that the expansion of the ring in L-659,877 by substitution of ${\beta}Ala$ for Gly at position 4 stabilized its conformation monitored by CD spectra. The results suggest that analogue 1 can be used as a new leader compound to design a more powerful, selective, and stable NK-2 receptor antagonist.

• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.300-308
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• 2018

The contribution analysis of various external aeroacoustic noise sources to interior noise is important, enabling to design an automobile with a low interior noise level. With a new technique, the CD (Cholesky Decomposition), it is proposed to decompose an overall interior noise spectrum into multiple spectra, each representing the contribution of a specific noise source to the interior noise. In order to validate this method, three kinds of experiments were conducted. Furthermore, it is proposed to improve the CD-based contribution analysis method to be integrated with existing exterior microphone arrays in the wind tunnel. This method was validated with an experiment with two speakers.

• Journal of Navigation and Port Research
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• v.37 no.5
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• pp.481-486
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• 2013

In this study, a commercial seakeeping program Seakeeper, integrated into Maxsurf, which is based on the linear strip theory was employed to compare the effect of bulbous bow (with/without) on motion response characteristics in a 18-meter catamaran. The seakeeping analyses were conducted at several Beaufort wind conditions such as scale No. 3 ($\bar{T}=2.98s$, $H_{1/3}$ =0.6m), No. 4 ($\bar{T}=3.85s$, $H_{1/3}$ =1m) and No. 5 ($\bar{T}=5.44$, $H_{1/3}$ =2m) based on ITTC wave spectrum. Pitch motion response spectrum was calculated at Head sea, Head & bow sea and Beam sea as encounter angles. Hull form of a catamaran with bulb showed the maximum 20% decrease of pitch motion response as compared to that of hull form without bulb.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.126-126
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• 2014

Label-free biomolecular assay based localized surface plasmon resonance (LSPR) of noble metal nanoparticles enables simple and rapid detection with the use of simple equipment. Nanosized metal nanoparticles exhibit a strong absorption band when the incident light frequency is resonant with the collective oscillation of the electrons, which is known as the LSPR. Here we demonstrate localized surface plasmon resonance (LSPR) substrates such as plasmonic Au nanodisks fabricated by a nanoimprinting process and gold nanorod-immobilized surfaces and their applications to highly sensitive and/or label-free biosensing. To increase detection sensitivity various bioreceptors weree designed. A single chain variable fragment (scFv) was used as a receptor to bind C-reactive protein (CRP). The results of this effort showed that CRP in human serum could be quantitatively detected lower than 1 ng/ml. Aptamers, which were immobilized on gold nanorods, were used to detect mycotoxins. The specific binding of ochratoxin A (OTA) to the aptamer was monitored by the longitudinal wavelength shift of LSPR peak in the UV-Vis spectra resulting from the changes of local refractive index near the GNR surface induced by accumulation of OTA and G-quadruplex structure formation of the aptamer. According to our results, OTA could be quantitatively detected lower than 1 nM level. Additionally, aptamer-functionalized GNR substrate was quite robust and can be regenerated many times by rinsing at 70 OC to remove bound target. During seven times of washing steps, the developed OTA sensing system could be reusable. Moreover, the proposed biosensor exhibited selectivity over other mycotoxins with an excellent recovery for detection in grinded corn samples, suggesting that the proposed LSPR based aptasensor plays an important role in label-free detection of mycotoxins.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.4
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• pp.299-307
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• 2011

The offshore plants such as FPSO are subjected to combination loading of environmental conditions (swell, wave, wind and current). Therefore the fatigue damage is occurred in the operation time because the units encounter the environmental phenomena and the structural configurations are complicated. This paper is a research for frequency domain fatigue analysis of wide-band random loading focused on accuracy of fatigue damage estimation regarding the proposed methods. We selected ideal bi-modal spectrum. And comparison between time-domain fatigue analysis and frequency-domain fatigue analyses are conducted through the fatigue damage ratio. Fatigue damage ratios according to Vanmarcke's bandwidth parameter are founded for wide-band. Considering safety, we recommend that Jiao-Moan and Tovo-Benasciutti methods are optimal way at the fatigue design for wide-band response. But, it is important that these methods based on frequency-domain unstably change the accuracy according to the material parameter of S-N curve. This study will be background and guidance for the new frequency-domain fatigue analysis development in the future.