• Ocean and Polar Research
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• v.33 no.3
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• pp.309-319
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• 2011

This is a preliminary study of the feasibility of obtaining reliable tidal current harmonic constants, using one month of current observations, to verify the accuracy of a tidal model. An inference method is commonly used to separate out the tidal harmonic constituents when the available data spans less than a synodic period. In contrast to tidal constituents, studies of the separation of tidal-current harmonics are rare, basically due to a dearth of the long-term observation data needed for such experiments. We conducted concurrent and monthly harmonic analyses for tidal current velocities and heights, using 2 years (2006 and 2007) of current and sea-level records obtained from the Tidal Current Signal Station located in the narrow waterway in front of Incheon Lock, Korea. Firstly, the l-year harmonic analyses showed that, with the exception of $M_2$ and $S_2$ semidiurnal constituents, the major constituents were different for the tidal currents and heights. $K_1$, for instance, was found to be the 4th major tidal constituent but not an important tidal current constituent. Secondly, we examined monthly variation in the amplitudes and phase-lags of the $S_2$ and $K_1$ current-velocity and tide constituents over a 23-month period. The resultant patterns of variation in the amplitudes and phase-lags of the $S_2$ tidal currents and tides were similar, exhibiting a sine curve form with a 6-month period. Similarly, variation in the $K_1$ tidal constant and tidal current-velocity phase lags showed a sine curve pattern with a 6-month period. However, that of the $K_1$ tidal current-velocity amplitude showed a somewhat irregular sine curve pattern. Lastly, we investigated and tested the inference methods available for separating the $K_2$ and $S_2$ current-velocity constituents via monthly harmonic analysis. We compared the effects of reduction in monthly variability in tidal harmonic constants of the $S_2$ current-velocity constituent using three different inference methods and that of Schureman (1976). Specifically, to separate out the two constituents ($S_2$ and $K_2$), we used three different inference parameter (i.e. amplitude ratio and phase-lag diggerence) values derived from the 1-year harmonic analyses of current-velocities and tidal heights at (near) the short-term observation station and from tidal potential (TP), together with Schureman's (1976) inference (SI). Results from these four different methods reveal that TP and SI are satisfactorily applicable where results of long-term harmonic analysis are not available. We also discussed how to further reduce the monthly variability in $S_2$ tidal current-velocity constants.

• Journal of Environmental Science International
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• v.23 no.4
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• pp.661-672
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• 2014

Due to tidal force, it is very difficult to estimate the hydraulic parameters of high permeable aquifer near coastal area in Jeju Island. Therefore, to eliminate the impact of tidal force from groundwater level and estimate the hydraulic properties, tidal response technique has been mainly studied. In this study we have extracted 38 tidal constituents from groundwater level and harmonic constants including frequency, amplitude, and phase of each constituent using T_TIDE subroutine which is used to estimate oceanic tidal constituents, and then we have estimated hydraulic diffusivity associated with amplitude attenuation factor(that is the ratio of groundwater level amplitude to sea level amplitude for each tidal constituent) and phase lag(that is phase difference between groundwater level and sea level for each constituent). Also using harmonic constants for each constituent, we made the sinusoidal wave and then we constructed the synthesized wave which linearly combined sinusoidal wave. Finally, we could get residuals(net groundwater level) which was excluded most of tidal influences by eliminating synthesized wave from raw groundwater level. As a result of comparing statistics for synthesized level and net groundwater level, we found that the statistics for net groundwater level was more insignificant than those of synthesized wave. Moreover, in case of coastal aquifer which the impact of tidal force is even more than those of other environmental factors such as rainfall and groundwater yield, it is possible to predict groundwater level using synthesized wave and regression analysis of residuals.

• Bulletin of the Korean Chemical Society
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• v.3 no.2
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• pp.44-49
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• 1982

Dynamic and equilibrium structures of a polymer chain immersed in solvent molecules have been investigated by a molecular dynamic method. The calculation employs the Lennard-Jones potential function to represent the interactions between two solvent molecules (SS) and between a constituent particle (monomer unit) of the polymer chain and a solvent molecule (CS) as well as between two non-nearest neighbor constituent particles of the polymer chain (CC), while the chemical bond for nearest neighbor constituent particles was chosen to follow a harmonic oscillator potential law. The correlation function for the SS, CS and CC pairs, the end-to-end distance square and the radius of gyration square were calculated by varying the chain length (= 5, 10, 15, 20). The computed end-to-end distance square and the radius of gyration square were found to be in a fairly good agreement with the corresponding results from the random-flight model. Unlike earlier works, the present simulation rsesult shows that the autocorrelation function of radius of gyration square decays slower than that of the end-to-end distance square.

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.191-191
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• 2017

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.6
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• pp.583-592
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• 2010

Equations of motion of thin-walled composite H-type cross-section beams exposed to concentrated harmonic and non-harmonic time-dependent external excitations, incorporating a number of nonclassical effects of transverse shear, primary and secondary warping, and anisotropy of constituent materials are derived. The forced vibration response characteristics of a composite H-type cross-section beam exhibiting the circumferentially asymmetric stiffness(CAS) configuration are exploited in connection with the structural bending-torsion coupling resulting from directional properties of fiber reinforced composite materials.

• Journal of Ocean Engineering and Technology
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• v.16 no.2
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• pp.6-9
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• 2002

The long-term monthly variations of tide with tidal harmonic analysis in Pusan Harbour are investigated. The present spring tidal range decreased 1.4 cm and the variation of phase lag increased than 1974. The high and low water level of yearly mean sea level is show during the February to March and August to September, respectively. It is important to note that the larger lunar elliptic N2 is large in comparison with lunisolar diurnal K1 and principal lunar diurnal O1. The ratios (Correction Factors) of monthly mean sea level and the main 4 tidal constituents are evaluated to correct the shortly (monthly) observed tide for the design of harbour facilities.

• Water for future
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• v.24 no.2
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• pp.81-95
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• 1991

For investigation of the interaction of tide and river flow, the derived equations are solved analytically using the approximation method of perturbation. The convective inertia and nonlinear bottom friction terms are included in the derivations. The harmonic analysis is applied to decompose the complicated interaction of the freshwater discharge with various constituents of tide into its individual interaction with each constituent. In this study, four main constituents(M2, S2, Kl, 01) are included. The relations of dimensionless parameters of the tide, especially the dimensionless damping modulus, are then determined for each solution. The results show that analytical solution of dimensionless damping modulus underestimates the measured value obtained from harmonic analysis. Results of water level obtained by applying the analytical model to a tidal reach of the Keum River in the years 1981 and 1982 show very good agreement with those obtained from the harmonic analysis.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.1
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• pp.14-24
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• 2008

Recently, rising tendency of high water level is detected at southwestern coast. The result of harmonic analysis shows increasing trend of mean sea level, decreasing trend of the amplitudes of semi-diurnal tidal constituents, and increase of Sa tidal constituent, therefore, additional increase of high water level at Summer season. It shows also that maximum surge level has increased greatly, according to the frequent visit of big typhoon such as RUSA and MAEMI. Considering the correspondence of Sa and typhoon period, namely July${\sim}$September, extraordinary high water level would be more probable. Especially, Mokpo and Jeju would be considered to have many chances of extraordinary high water level in the future.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.59-62
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• 2010

The limitation of constant for tide correction is identified using the T_tide $MATLAB^{(R)}$ package. A suggestion is presented in calculation of local phase lag(k) by a/15 (a is angular speed of any constituent in degree) from the g, phase lag measured by standard time meridian latitude.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.2
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• pp.85-90
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• 2012

This paper presents a topology structure and control method for an input-parallel-output-series(IPOS) inverter system which is suitable for high input current, high output voltage, and high power applications. In order to ensure the normal operation of the IPOS inverter system, the control method should achieve input current sharing(ICS) and output voltage sharing(OVS) among constituent modules. Through the analysis in this paper, ICS is automatically achieved as long as OVS is controlled. The IPOS inverter system is controlled by a three-loop control system which is composed of an outer common-output voltage loop, inner current loops and voltage sharing loops. Simulation results show that this control strategy can achieve low total harmonic distortion(THD) in the system output voltage, fast dynamic response, and good output voltage sharing performance.