• Journal of the Society of Naval Architects of Korea
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• v.56 no.2
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• pp.103-108
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• 2019

A new state-of-the-art sloshing research equipment has developed to perform the model test of LNG tanks for the safer design of LNG cargo containment system in violent sloshing phenomena. This sloshing test system has developed by the Samsung Ship Model Basin (SSMB) and thoroughly verified. The accuracy of the motion of hexapods equipment for the excitation of a model tank has been verified. The maximum displacement in six degrees of freedom, harmonic motions of various frequencies, and irregular motions in wave conditions are measured and compared with input signals. In order to confirm the reliability of the post-processing program for measured impact pressure, the post-processed results were compared with those of the reference institute. A benchmarking sloshing test using 1/50 scale model of 160K LNGC tank was conducted for the verification of the whole testing system. The partial filing levels were considered. As a result of the experiment, it is confirmed that the results are in good agreement with those of the reference institute.

• Journal of the Korean Chemical Society
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• v.64 no.6
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• pp.334-344
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• 2020

The adsorption of various atmospheric harmful gases (COx, NOx, SOx) on graphene-like Germanene 2D sheet was theoretically investigated using density functional theory(DFT) method. The structures were fully optimized at the B3LYP/cc-pvDZ and CAM-B3LYP/cc-pvDZ levels of theory and confirmed to be a local minimum by the calculation of the harmonic vibrational frequencies. The adsorptions of gases on the Germanene sheet were predicted to be a physisorption process for CO, CO2, NO, and SO2 gases but to be a chemisorption process for NO2, SO, and SO2 gases.

• Journal of the Korean Chemical Society
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• v.53 no.1
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• pp.7-16
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• 2009

The global minimum structures of the benzene-water, Bz-$H_2O$ and benzene-water cation complex, [Bz-$H_2O]^+$ have been investigated using ab initio and density functional theory(DFT) with very large basis sets. The highest levels of theory employed in this study are B3LYP/cc-pVQZ for geometry optimization and MP2/aug-cc-pVTZ//B3LYP/aug-cc-pVTZ for binding energy. The harmonic vibrational frequencies and IR intensities are also determined at the various levels of theory to confirm whether the structure of water complex is affected by the presence of benzene. The binding energies of Bz-$H_2O$ (N-1) structure are predicted to be 3.92 kcal/mol ($D_e$) and 3.11 kcal/mol ($D_0$) after the zero-point vibrational energy correction at the MP2/cc-pVQZ//B3LYP/cc-pVQZ level of theory. The binding energies of [Bz-$H_2O]^+$ (C-1) structure are predicted to be 9.06 kcal/mol for $D_e$ and 7.82 kcal/mol for $D_0$ at the same level of theory.

• Journal of the Korean Chemical Society
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• v.59 no.5
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• pp.387-396
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• 2015

The DFT and ab initio calculations have been performed to elucidate hydrogen interaction of HOOO-(H₂O)_n (n=1~5) clusters. The optimized geometries, harmonic vibrational frequencies, and binding energies are predicted at various levels of theory. The trans conformer of HOOO monomer is predicted to be thermodynamically more stable than cis form at the CCSD(T) level of theory. For HOOO-(H₂O)_n clusters, the geometries are optimized at B3LYP/aug-cc-pVTZ and CAM-B3LYP/aug-cc-pVTZ levels of theory. The binding energy of HOOO-H₂O cluster is predicted to be 6.05 kcal/mol at the MP2//CAM-B3LYP/ aug-cc-pVTZ level of theory after zero-point vibrational energy (ZPVE) and basis set superposition error (BSSE) correction. The average binding energy per H₂O is increased according to adding a H₂O moiety in HOOO-(H₂O)_n clusters up to 7.2 kcal/mol for n=5.

• 한국해양학회지
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• v.2 no.1_2
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• pp.24-33
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• 1967

The variations of monthly mean sea levels along the coast of Korea anre studied graphic and harmonic methods with the data from 9 tides stations and compared with the variations of atmospheric pressure and the changes in density of sea water measured near some of the stations. The monthly mean sea level generally rises in Summer to Autumn, and falls in Winter to Spring and its range is from 20 cm to 50 cm. The variation of monthly mean sea level is of annual type, having one maximum and one minimum. The semi-range of annual components is 10.5 cm at Pusan and increases to the north in the west coast, to 20.8 cm at Inchon. It's phase is, on the whole, similar for the entire coast with about 210 (middle of August), except at Inchon, 200 . The variation of monthly mean sea level is mainly isostatic, or caused by those of sea water density and atmospheric pressure. Especially, the steric effect is predominant on the south- east coast around Pusan. However, in shallow long bays and estuaries on the west coast, the river runoff effect as well as local wind effect is also considerable. Magnitudes of annual variations at each stations are not constant, but widely variable from year to year. On the east and south coast, especially at Ulneungdo and Pusan the variations are large, which seem to be connected with the shifting of main current axes or current patterns in the offing.

• Journal of Physiology & Pathology in Korean Medicine
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• v.26 no.6
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• pp.970-975
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• 2012

In Sasang constitutional medicine, doctors diagnose and treat patients according to their Sasang consitutition (SC) type. In this work, by a clinical test with a radial pulse tonometer, we investigated radial pulse properties which were significant in distinguishing unhealthy subjects from healthy subjects for each SC type. We measured radial pulse properties on left and right Gwan locations with a pulse tonometer for 299 elderly female subjects of age of 50 years old or above. We used a newly developed SCAT system to determine subjects' SC types. Subjects' health levels of either healthy or unhealthy were determined independently by two Korean medical doctors. To investigate the statistical differences, we used either of Student's t-test or Mann-Whitney U test depending on the normality of distribution of test statistic. For TE type, unhealthy subjects were characterized with significant increases in heart rate, systolic to diastolic period, pulse depth, while they showed significant decreases in width of pulse in normal direction, pulse area in diastolic period, and high harmonic components (6th, 7th) of power spectral density. For SE type, unhealthy subjects were characterized with significant increases in pulse pressure and pulse depth, while no significant differences were found for SY type. We investigated the characteristic differences in radial pulse properties due to change in health levels on each SC type for elderly females. Pulse variables which were significantly different between healthy subjects and unhealthy subjects were found to vary between SC types. For TE type subjects, many variables were found significant at the left Gwan location, which is in support of the theory of hyperactive liver functioning for TE type. Irrespective of the constitution, the related changes in the pulse properties due to worsened health level were in support of elevated blood flow amount in compensation with weakened blood circulatory function.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.464-473
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• 2016

The air temperatures of the coast and inland are rising due to an increase in carbon dioxide emissions and abnormal climate phenomena caused by global warming, El Nino, La Nina and so on. The sea levels of the Earth are rising by approximately 2.0 mm per year (global average value) due to the thermal expansion of sea water, melting of glaciers and other causes by global warming. On the other hand, when it comes to designing a hydraulic structure or coastal hydraulic structure, the standard of the design water level is decided by analyzing four largeness tide values and a harmonic constant with the observed tidal water level or simulating numerical model. Therefore, the design tidal water level needs to consider an increasing speed of the seawater level, which corresponds to the design frequency. In the present study, the observed tidal water levels targeting 46 tidal stations operated by the Korea Hydrographic and Oceanographic Administration (KHOA) from the beginning of observations to 2015 per hour were collected. The variation of the monthly and yearly and increasing ratio were performed and divided into 7 seas, such as east and west part of the Southern Sea, south part and middle of the East Sea, south part and middle of the Western Sea, and Jeju Sea. The current study could be used to determine the cause of local seawater rises and reflect the design tidal water level as basic data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.121-128
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• 2010

This paper presents a design of a 100 W high-efficiency power amplifier, whose operational frequency band expands from 30 to 512 MHz, using negative feedback network, push-pull structure, broadband RF choke, and transmission line transformer for balun configuration. The push-pull amplifier has been tuned for higher output power using a shunt capacitor as a matching component at its load especially for high-frequency region. The implemented power amplifier exhibited a very flat power gain of $18.34{\pm}0.9\;dB$ throughout the operating frequency band and very high power-added efficiency(PAE) of greater than 40% at an output power of 100 W. It also showed second- and third-harmonic distortion levels of below -34 dBc and -12 dBc, respectively, through the entire operating frequency band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.2
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• pp.152-160
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• 2013

In this paper, to the aim of wideband SSN(Simultaneous Switching Noise) suppression characteristic, investigation of spiral resonator are used in conjunction with bead which is commonly used for noise suppression method. Bead works effectively to suppress the power noise up to the first harmonic of fundamental frequency, 0.8 GHz, and spiral resonator suppress noise well in the frequency range of SRF(Self Resonance Frequency) which is inversely proportional to the length of spiral. Thus, when bead used in conjunction with a spiral the noise suppression characteristic is determined by the one of higher impedance element of the two in the frequency range and achieves more broadband filtering characteristic. The case for using 22 nH bead turns out 4.8, 2.0, 0, and, 0.6 dB, and the case for using 22 nH bead in conjunction with 3-turns spiral achieves more wideband characteristic of 9.5, 8.3, 6.1, and 9.9 dB power noise suppression performances at the first, second, third, and fourth harmonics, respectively. The peak-to-peak voltage levels decrease from 76 mV to 56 mV using 22 nH bead, and the level decrease rapidly to 34 mV when using in conjunction with bead and 3-turn spiral. Thus more wideband SSN suppression characteristic can be achieved using bead with spiral.

• Journal of the Korean Chemical Society
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• v.61 no.1
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• pp.16-24
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• 2017

The adsorption of various atmospheric harmful gases ($CO_x$, $NO_x$, $SO_x$) on graphene-like boron nitride(BN) and aluminum nitride(AlN) sheets was theoretically investigated using density functional theory (DFT) and MP2 methods. The structures were fully optimized at the $B3LYP/6-31G^{**}$ and $CAM-B3LYP/6-31G^{**}$ levels of theory and confirmed to be a local minimum by the calculation of the harmonic vibrational frequencies. The MP2 single-point binding energies were computed at the $CAM-B3LYP/6-31G^{**}$ optimized geometries. Also the zero-point vibrational energy (ZPVE) and 50%-basis set superposition error (BSSE) corrections were included. The adsorptions of gases on the BN sheet were predicted to be a physisorption process and the adsorptions of gases on the AlN sheet were predicted to be a physisorption process for $CO_x$ and $NO_x$ but to be a chemisorption process for $SO_x$.