• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.10a
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• pp.63-68
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• 1990

The nature of fluctuating air pressure inside building was studied by testing a building model in a wind tunnel. The model has a single room and a sin81e window opening. Various opening conditions were tested in both laminar uniform wind and turbulent boundary-layer wind. The RMS and the spectra of the fluctuating internal pressure were measured. The test results support a recent theory which predicts the behavior of internal pressure under high wind based on aerodynamic analysis.

• Nuclear Engineering and Technology
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• v.35 no.5
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• pp.497-505
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• 2003

This paper describes a computational approach to the quantification of primary damage under irradiation and demonstrates the effect of neutron energy spectra on the formation of the displacement cascade. The development of displacement cascades in ${\alpha}-Iron$ has been simulated using the MOLDY code - a molecular dynamics code for simulating radiation damage. The primary knock-on atom energy, key input to the MOLDY code, was determined from the SPECTER code calculation on two neutron spectra. The two neutron spectra include; (i) neutron spectrum in the instrumented irradiation capsule of the high-flux advanced neutron application reactor (HANARO), and (ii) neutron spectrum at the inner surface of the reactor pressure vessel steel for the Younggwang nuclear power plant No.5 (YG 5). Minor differences in the normalized neutron spectra between the two spectra produce similar values of PKA energy, which are 4.7 keV for HANARO and 5.3 keV for YG 5. This similarity implies that primary damage to the components of the commercial nuclear reactors should be well simulated by irradiation in the HANARO. Moreover, the application of the MD calculations corroborates this statement by comparing cascades simulation results.

• Wind and Structures
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• v.24 no.5
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• pp.501-528
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• 2017

In this work, wind tunnel tests of pressure measurements are carried out to assess the global aerodynamic interference factors, the local wind pressure interference factors, and the local lift spectra of an square high-rise building interfered by an identical cross-sections but lower height building arranged in various relative positions. The results show that, when the interfering building is located in an area of oblique upstream, the RMS of the along-wind, across-wind, and torsional aerodynamic forces on the test building increase significantly, and when it is located to a side, the mean across-wind and torsional aerodynamic forces increase; In addition, when the interfering building is located upstream or staggered upstream, the mean wind pressures on the sheltered windward side turn form positive to negative and with a maximum absolute value of up to 1.75 times, and the fluctuating wind pressures on the sheltered windward side and leading edge of the side increase significantly with decreasing spacing ratio (up to a maximum of 3.5 times). When it is located to a side, the mean and fluctuating wind pressures on the leading edge of inner side are significantly increased. The three-dimensional flow around a slightly-shorter disturbing building has a great effect on the average and fluctuating wind pressures on the windward or cross-wind faces. When the disturbing building is near to the test building, the vortex shedding peak in the lift spectra decreases and there are no obvious signs of periodicity, however, the energies of the high frequency components undergo an obvious increase.

• Journal of Korean Association for Spatial Structures
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• v.20 no.2
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• pp.69-76
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• 2020

Wind tunnel tests were conducted to analyze the wind fluctuating pressures on a circular closed and open dome roof with a low span rise. Two dome models with various geometric parameters (height/span ratios and open ratios) were used for fixed span rise ratio dome and wind pressure spectrum were analyzed. The applicability was examined in comparison with the spectral model proposed in the previous studies. The analysis results show that the wind pressure spectrum of open dome roof tends to increase power in the high frequency range and the second peak is found in the area different from the closed dome roof. In addition, according to the comparison analysis with the previous proposed spectral model, it was found that it is not applicable to the closed and open dome roofs with low rise ratio due to the different peak frequencies.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.7
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• pp.569-574
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• 2014

In order to investigate low frequency swishing noise of wind turbines, acoustic source model using a singularity in circular motion is introduced to derive analytic solution of Lowson acoustic analogy in time domain. Results in time and frequency domains computed by the solution show apparent modulation of amplitude and frequency. The solution indicates that time histories of acoustic pressure at receiver points varied significantly according to receiver's directional location, even when the retarded time distributions are similar. However, the corresponding time-averaged spectra of sound pressure at the receiver locations where the retarded time distributions are almost same are not significantly different. It can be inferred from these results that the time-averaged sound pressure spectra which cannot take into account the detailed difference in the time-variation of wind turbine noise may not represent the sound quality of wind turbines due to its swishing. Finally, as an introduction of procedure to quantify low frequency swishing noise level, relative variation of overall sound pressure level is obtained using tonal low frequency noise model.

• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1084-1088
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• 1995

A complete solid solution (SrLaAl1-xNixO4) between insulating SrLaAlO4 and metallic SrLaNi(Ⅲ)O4 oxides were prepared under high oxygen pressure (1.5 kbar, 800 ℃). They have tetragonal K2NiF4-type structure in all the solid solution range. Compared with lattice parameters of the same solid solution prepared under normal condition (1 bar, 1200 ℃), large decrease in the c-parameter was induced by high pressure treatment while no noticeable variation of the a-parameter was observed. Although marked changes of structural parameters, magnetic susceptibilities, and electron paramagnetic resonance spectra were consistently occurred before and after x=0.5, overall behaviors were essentially the same with those of solid solution prepared under normal condition. Such a phenomenon is explained by assuming the formation of partially filled narrow σ*x2-y2 band for x>0.5. Lattice contraction along the c-axis by high pressure treatment seems not to broaden this band. Particularly, the continuous absorption characteristic of a high free carrier concentration for x>0.5 and the absence of Ni-O in-plane stretching mode in the infrared absorption spectra supports this picture. However, the conductivities increasing with temperature for all solid solution suggest that some localization character, of probably Anderson type, remains for x>0.5.

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

• Mass Spectrometry Letters
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• v.3 no.2
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• pp.29-38
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• 2012

A new approach of volatile compounds analysis is proposed using a linear ion trap Orbitrap mass spectrometer coupled with gas chromatography through an atmospheric pressure photoionization interface. In the proposed GC-HRMS/MS approach, direct chemical composition analysis is made for the precursor ions in high resolution MS spectra and the structural identifications were made through the database search of high quality MS/MS spectra. Successful analysis of a complex perfume sample was demonstrated and compared with GC-EI-Q and GC-EI-TOF. The current approach is complementary to conventional GC-EI-MS analysis and can identify low abundance co-eluting compounds. Toluene co-sprayed as a dopant through API probe significantly enhanced ionization of certain compounds and reduced oxidation during the ionization.

• Atmosphere
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• v.25 no.3
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• pp.559-568
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• 2015

As is evident from its definition, Southern Oscillation Index variability conformed to a combination of the variations of Darwin and Tahiti pressure. Over the El-$Ni{\tilde{n}}o$ Southern Oscillation spectra, the Darwin pressure shared variations associated with the SSN tendency while the Tahiti had a connection with the stratospheric quasi-biennial oscillation modulating annual cycle. The power peak near the 3.5-year period comprised the third harmonic of the sun and the second of the modulated annual cycle. The derived harmonics came from both sources, so the initiation of El-$Ni{\tilde{n}}o$ could be predicted more successfully when including the effects of the sun and QBO.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.141-145
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• 2003

The rotary compressor is widely used for the air conditioner because it is efficient and compact. In recent, the need for silent compressors is much stronger than the past. The new type muffler was invented to reduce noise level and to improve sound quality. The new type muffler that has two side discharge holes represents much lower overall noise level, especially noise levels around 1KHz than the old type one that has one center discharge hole in acoustic spectra and dynamic pressure spectra. The noise reduction effects of the new type muffler were verified by noise tests for rotary compressors and air conditioners.