• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.410-414
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• 1998

The dependence of substrate material and electrode position were studied by radiation analysis of Ar discharge, and electron beam radiation was applied to confirm the crosslinked structure of the film. Comparing the conductor substrate with the insulator substrate, the former had lager peak density of radiation spectrum than latter. From the result of peak density of metastable state and ion, it was confirmed that the peak density of ion was falling to the down limit with increasing the distance of electrode by analyzing the radiation spectrum of polymerized films. When the polymerized styrene films was exposed to electron beam, it was possible to form a pattern with the insulator substrate.

• The Journal of Natural Sciences
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• v.7
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• pp.19-25
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• 1995

In this study, the Mossbauer effect of the $NiAl_0.8Fe_1.2O_4$ was investigated in the temperature range of 77K-1000K. The spectra were composed of two component, one is sixtet and the other doublet, at low temperature. From the temperature dependence of Mossbauer spectum, it is appeared that the magnetic properties of $NiAl_0.8Fe_1.2O_4$ varies from ferrimagnetism to paramagnetism as the increasing tempereture. And the magnetic relaxation patterns of the $NiAl_0.8Fe_1.2O_4$ were shown superparamagnetic effect.

• Computational Structural Engineering : An International Journal
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• v.2 no.1
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• pp.33-42
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• 2002

A computationally efficient stiffness design method for building structures is proposed in which dynamic soil-structure interaction based on the wave-propagation theory is taken into account. A sway-rocking shear building model with appropriate ground impedances derived from the cone models due to Meek and Wolf (1994) is used as a simplified design model. Two representative models, i.e. a structure on a homogeneous half-space ground and a structure on a soil layer on rigid rock, are considered. Super-structure stiffness satisfying a desired stiffness performance condition are determined via an inverse problem formulation for a prescribed ground-surface response spectrum. It is shown through a simple yet reasonably accurate model that the ground conditions, e.g. homogeneous half-space or soil layer on rigid rock (frequency-dependence of impedance functions), ground properties (shear wave velocity), depth of surface ground, have extensive influence on the super-structure design.

• Journal of Radiation Protection and Research
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• v.11 no.1
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• pp.3-14
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• 1986

A stud has been carried out for figuring out real photon spectrum from an observed gamma-ray spectrum by means of response matrix method, which is known one of the relatively convenient method for the estimation of exposure rate of a complex gamma ray field in comparison with graphical analysis and least square fitting of the measured spectrum. A 3'${\times}$3' cylindrical Nal(T1) scintillation detector in association with multichannel pulse height analyzer and six reference gamma ray sources covering the photon energy range of 0.05 to 2.0 MeV were used. In dividing the energy region for the construction of response matrix, two different approaches were attempted. One is dividing the entire energy region of interest into 20 bins, one of which corresponds to a width of 0.1 MeV to form $20{\times}20$ matrix, and another is dividing the 2 MeV region into 14 bins to form $14{\times}14$ matrix consists of $0.1(MeV)^{1/2}$ intervals assuming the resolution of the detector is dependent on square root of the incident photon energy. Inversion of thus constructed matrices was performed by a computor(P-E8/32) using the program attached to the end of this paper. The resultant exposure rates obtained by this method were in good agreement, within 10% with those calculated by ordinary formula widely used for a gamma-ray field of known energy and flux. It is concluded that the photen flux obtained by the response matrix constructed under the assumption of $E^{1/2}$ dependence is more realistic than that obtained by the matrix consist of identical energy bins in dosimetrical point of view.

• Bulletin of the Korean Chemical Society
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• v.24 no.8
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• pp.1126-1134
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• 2003

The signals obtained from the $5^{th}$-order (two-dimensional) Raman spectrum of a liquid can depend dramatically on the polarizations of the various light beams, but to date there has been no evidence presented that different polarization conditions probe any fundamentally different aspects of liquid dynamics. In order to explore the molecular significance of polarization we have carried out a molecular dynamics simulation of the $5^{th}$-order spectrum of a dilute solution of CS₂ in liquid Xe, perhaps the simplest system capable of displaying a full range of polarization dependencies. By focusing on the 5 distinct rotational invariants revealed by the different polarizations and by comparing our results with those from liquid Xe, a liquid whose spectrum has no significant polarization dependence, we discovered that the polarization experiments do, in fact, yield valuable microscopic information. With different linear combinations of the experimental response functions one can separate the part of the signal derived from the purely interaction-induced part of the many-body polarizability from the portion with the largest contributions from single-molecule polarizabilities. This division does not directly address the underlying liquid dynamics, but it significantly simplifies the interpretation of the theoretical calculations which do address this issue. We find that the different linear combinations differ as well in whether they exhibit nodal lines. Despite the absence of nodes with the atomic liquid Xe, observing the resilience of our solution's nodes when we artificially remove the anisotropy of our solute leads us to conclude that there is no direct connection between nodes and specifically molecular degrees of freedom.

• Macromolecular Research
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• v.12 no.3
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• pp.276-281
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• 2004

In this study we investigated the spectral properties, including electric absorption, circular and linear dichroism (CD and LD), and fluorescence emission, of DNA in a DNA-branched polyethyleneimine (BPEI) polyplex at various polymer molecular weights (M$\_$w/) and BPEI-amine-to-DNA-phosphate ratios (N/P ratios). All BPEIs exhibited a common N/P dependence in their absorption and CD spectra. At N/P ratios ＜ 1.0, we observed some hyperchromism in the absorption spectrum, red-shifts in CD bands, and decreases in LD intensity and fluorescence intensity of intercalated ethidium. At intermediate N/P ratios, complete collapse of all spectra occurred. As the N/P ratio increased further, the polyplex dissolved in water. From its characteristic CD spectrum obtained under these conditions, we conclude that the DNA exists in a B-like form. The fluorescence and LD intensities never recovered even at high N/P ratios- which indicates that the dissolved polyplex possesses positive charges and the DNA in the polyplex is condensed despite its B-form CD spectrum. The N/P range in which the absorption and CD signals collapsed was wider when the BPEIs M$\_$w/ decreased. In the case where the BPEIs M$\_$w/ was 0.8 k, recovery of the absorption and CD spectral properties at a high N/P ratio was never achieved, which suggests that the molecular weight of the polymer plays an important role in its dissolution at a high N/P ratio.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.745-748
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• 1995

Magnetic nanoparticles of iron and iron oxide have been prepared in a modified upward thermal diffusion cloud chamber using pulsed laser evaporation. SEM/TEM studies of these particles reveal a size distribution with a mean diameter of about $60\;{\AA}$. FTIR spectrum measurements are used to investigate the difference in oxidation level between nanoparticles prepared at different partial oxygen pressures. The complex magnetic behaviour of these particles was studied using DC- and AC-susceptibility measurements. All samples exhibit superparamagnetism with blocking temperatures ranging from 50 K to above room temperature. The coercivity fields as well as the dependence of the blocking temperature on measuring frequency have been studied. magnetic anisotropy constants are found to be one order of magnitude higher than is known for the bulk values. The mean particle size estimated from the magnetic data is found to be in perfect agreement with the TEM observations.

• Journal of Mechanical Science and Technology
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• v.17 no.11
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• pp.1599-1607
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• 2003

The characteristics of elastic waves emanated from crack initiation in 6061 aluminum alloy subjected to fatigue loading are investigated through experiments. The objective of the study is to determine the differences in the properties of the signals generated from fatigue test and also to examine if the sources of the waves could be identified from the temporal and spectral characteristics of the acoustic emission (AE) waveforms. The signals are recorded using nonresonant, flat, broadband transducers attached to the surface of the alloy specimens. The time dependence and power spectra of the signals recorded during the tests were examined and classified according to their special features. Six distinct types of signals were observed. The waveforms and their power spectra were found to be dependent on the crack propagation stage and the type of fracture associated with the signals. The potential application of the approach in health monitoring of structural components using a network of surface mounted broadband sensors is discussed.

• Bulletin of the Korean Chemical Society
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• v.20 no.10
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• pp.1149-1152
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• 1999

1H NMR spectrum of a DMF-d7 solution containing 4-aminopyrimidine and [SiW11CoIIO39]6- (SiW11Co) shows separate peaks from two linkage isomers, a and b, in which N(1) and N(3) of the pyrimidine ring are coordinated to SiW11Co, respectively. The signal from the amine group in the isomer a exhibits temperature dependence that is characteristic of a two-site exchange problem. Rates of internal rotation of the amine group were determined by simulating the NMR spectra at 5-35℃. The amine group of free 4-aminopyrimidine also shows temperature-dependent spectra at lower temperatures; rates of internal rotation at (-25)-25℃ were determined. The internal rotation of the amine group in the complex is much slower than that for free 4-aminopyrimidine, indicating that π-character of the C-N bond increases on coordination to SiW11Co. The amine group in the isomer b does not show such behavior. It is probable that hydrogen bonding between N-H and a bridging oxygen atom of SiW11Co prevents it from rotating at low temperatures.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.3
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• pp.1-6
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• 2014

We measured color rendering index(CRI) of a LED lamp for lighting for aging-time. We chose bulb type white LED lamp six samples and halogen lamp one sample and applied 220V, 60Hz to all the samples for 1,000hours at ordinary temperature. The CRI was measured every 20hours and the CRI change of the LED lamp was compared with the halogen lamp's CRI change. As time goes, efficiency of the halogen lamp decreased and the CRI maintained uniformly. The other hand, efficiency of the LED lamp decreased but the CRI increased. The CRI of the LED lamp has been stabilized since 600hours. The CRI change of the LED lamp was analyzed with a spectrum, color coordinate and color temperature.