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

• Spatial Information Research
• /
• v.16 no.2
• /
• pp.173-192
• /
• 2008

Recent climate fluctuation and environmental change at global scale are causing more incidences of disasters and calamities over the world. In a response to this environmental crisis, international collaboration for Earth Observation(EO) is obtaining more significance in order to understand, watch, and forecast changes in the earth system. As such, aerial monitoring based on remotely sensed data, indispensable for EO, is also drawing more attentions. In this context, we discuss diverse aspects of future developments in the Korean domestic system for aerial monitoring. This paper first thoroughly examines current status of national and international collaboration system arid research of aerial monitoring. It then suggests specific development plans for four critical dimensions such as research, organization, institutional systems, and strategies. Our study would facilitate systematically establishing policies for aerial monitoring in Korea and creating a domestic GEOSS(Global Earth Observation System of Systems) in the near future.

• Journal of The Korean Astronomical Society
• /
• v.38 no.2
• /
• pp.117-120
• /
• 2005

Current instrumentation activities and the open user status of Okayama Astrophysical Observatory (OAO) are reviewed. There are two telescopes in operation and one telescope under reforming at OAO. The 188cm telescope is provided for open use for more than 200 nights in a year. The typical over-subscription rate of observation proposals for the 188cm telescope is ${\~}$ 1.5 - 2. The 50cm telescope is dedicated to $\gamma$-ray burst optical follow-up observation and is operated in collaboration with Tokyo Institute of Technology. The 91cm telescope will become a new very wide field near-infrared camera in two years. The high-dispersion echelle spectrograph (HIDES) is the current primary instrument for the open use of the 188cm telescope. Two new instruments, an infrared multi-purpose camera (ISLE) and an optical low-dispersion spectrograph (KOOLS), are now under development. They will be open as common use instruments in 2006.

• Corrosion Science and Technology
• /
• v.15 no.6
• /
• pp.265-270
• /
• 2016

The ellipso-microscopic observation of a titanium surface undergoing anodization in $0.05mol\;dm^{-3}$ of $H_2SO_4$ was conducted. During irradiation by ultra-violet (UV) light with a wavelength of 325 nm, the titanium surface allowed for the flow of a photo-induced current and showed up as a bright, patch-like image on an ellipso-microscopic view. The brightness and patch-pattern in the image changed with flowing photo-induced current. The changes in the brightness and the image corresponded to the formation and/or degradation of titanium oxide due to the photo-electrochemical reaction of the oxide. An in situ monitoring using the ellipso-microscope revealed that the film change was dependent on the irradiation light power, by UV-light increases the anodic current and results in the initiation of pitting at lower potentials as compared with the non-irradiated condition.

• The Bulletin of The Korean Astronomical Society
• /
• v.46 no.2
• /
• pp.79.2-79.2
• /
• 2021

We explore the range of possibilities of temperatures, heated temperature, and Kappa values of a current sheet observation on 2017 September 10. First, we construct a grid model with rapid heating (T_heat) and various Kappa (κ) values. We assume a simple density model and use adiabatic cooling to set the temperature during expansion. Next, we calculate the ion fractions using a time-dependent ionization model with adiabatic cooling and various Kappa values. The calculated ion fractions are used to simulate the DNs of the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory. Then, we explore the possible range of the temperatures and Kappa values, comparing the simulated images with the observations. Finally, we discuss the range of the heated temperature and Kappa values and whether the result of this study suggests continuous heating of the current sheet plasma during the expansion.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.24 no.1
• /
• pp.12-16
• /
• 1988

The observation of the tidal current and the bottom contour around the set net fishing ground were carried out at four different regions of the southern part of Korea in order to obtain the basic information on the migrating course of fishes. The bottom contour was surveyed with portable echo sounder, and the tidal current was observed by two different methods at the same time. One was 25 hour observation at the fixed position with self-recording current meter (Inter Ocean Model 135 type) and the other was the drift observation of radar reflectors. Most of the set nets have been set near bottom valleys. It was regarded that the fish school became to dense easily near the valley according to the combined effect of the tidal current and the bottom contour.

• Journal of The Association for Neo Medicine
• /
• v.1 no.1
• /
• pp.115-122
• /
• 1996

A clinical observation was done on 98 cases performed neurometer diagnosis before Guibitang administration first, and rechecked neurometer diagnosis after Guibitang administration for 10 days. Electric current post administration was compared with ant administration. The following result were obtained. 1. A peak incidence was observed in 30-39 age group. 37 cases(37.8%) were in 30-39 age group. The ratio of male to female was 1:31.7. 2. Chief complaints were fatigue, menoxenia, indigestion, anorexia, constipation, headache, palpitation, insomnia etc. 3. The common result of neurometer point checking was that patients who had the pecularity of low electric current were much than patients who had the pecularity of high electric current. 4. By neurometer diagnosis a peak incidence was observed in gallbladder. Increment was also highest in gallbladder. Gallbladder has a function of psychomotility in oriental physiology. ?5. After Guibitang administration the increment of neurometer electric current was comparatively high in kidney, stomach, small intestine meridian. According to the above menthioned results I consider that Guibitang has the curative effects along the meridian selectively. and increases in function or preserves health within physycal limit.

• Journal of Ocean Engineering and Technology
• /
• v.37 no.2
• /
• pp.68-79
• /
• 2023

Even though submerged breakwater reduces incident wave energy, it redistributes the coastal area's wave-induced current, sediment transport, and morphological change. This study examines the coastal hydrodynamics and the morphological response of a wave-dominated beach with submerged breakwaters installed through field observation and quasi-3D numerical modeling. The pre-and post-storm bathymetry, water level, and offshore wave under storm forcing were collected in Bongpo Beach on the East coast of Korea and used to analyze the coastal hydrodynamic response. Four vertically equidistant layers were used in the numerical simulation, and the wave-induced current was examined using quasi-3D numerical modeling. The shore normal incident wave (east-northeast) generated strong cross-shore and longshore currents toward the hinterland of the submerged breakwater. However, the oblique incident wave (east-southeast) induced the southeastward longshore current and the sedimentation in the northeast area of the beach. The results suggested that the incident wave direction is a significant factor in determining the current and sediment transport patterns in the presence of the submerged breakwaters. Moreover, the quasi-3D numerical modeling is more appropriate for estimating the wave transformation, current, and sediment transport pattern in the coastal area with the submerged breakwater.

• Bulletin of the Korean Space Science Society
• /
• 2001.04a
• /
• pp.33-33
• /
• 2001

No Abstract, See Full Text

• Proceedings of the Korean Magnestics Society Conference
• /
• 2015.11a
• /
• pp.186-186
• /
• 2015