• 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.

• Ocean and Polar Research
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• v.39 no.3
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• pp.169-179
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• 2017

The "GeoDrifter" is a newly-developed surface drifter with high temporal resolution. It is the first time that high-frequency drifters have been deployed in the East/Japan Sea. The purpose of this study is to introduce the phenomena experienced by these drifters flowing along with the Tsushima Current across the East/Japan Sea, focusing on high-frequency variability, and to discuss them in comparison with previous observations. The observed basin-scale circulation of the Tsushima Current generally coincides well with the known schematic circulation. The GeoDrifter trajectories also show inertial oscillations almost everywhere in the oceanic regions of the East/Japan Sea, strong semi-diurnal tidal currents in the western part of Korea Strait, diurnal currents much stronger than semi-diurnal currents in the upstream region of the Nearshore Branch off the Japanese coast, and many warm eddies in the Yamato Basin, all comparable to the observational results reported in the previous studies. An interesting point is that the semi-diurnal tidal currents undergo a great spatial variation in the western part of the Korea Strait. The observed features that cannot be explained are, among others, strong counter-clockwise motions with oscillating period about 51 hours appearing in the upstream region of the Nearshore Branch off the Japanese coast and the different tidal behaviors between upstream and downstream regions of the latter.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.4
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• pp.393-403
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• 2008

In an effort to estimate secondary $PM_{10}$ concentrations and their diurnal variations at different photochemical activities, $PM_{10}$, CO, and $O_3$ concentrations obtained from the ambient air quality network located in Seoul are analyzed for the period from 2000 to 2005. In order to classify the photochemical activities on a daily basis, measured ${\Delta}O_{3,\;max-min}$ (maximum $O_3$-minimum $O_3$) and ${\int}(hv)dt$ which represents accumulated daily insolation, were used to classify each day into three regimes: 1) low photochemical reactivity; ${\Delta}O_{3,\;max-min}\;{\leq}\;40\;ppb$, and ${\int}(hv)dt\;{\leq}\;4000\;W/m^2$, 2) moderate photochemical reactivity; $40\;ppb\;<\;{\Delta}O_{3,\;max-min}\;{\leq}\;60\;ppb$, and $4000\;{\leq}\;{\int}(hv)de\;{\leq}\;6000\;W/m^2$, and 3) high photochemical reactivity; ${\Delta}O_{3,\;max-min}\;>\;60\;ppb$, and ${\int}(hv)dt\;{\geq}\;6000\;W/m^2$. The ratio of ($PM_{10}$/CO) obtained at low photochemical activity regime was used as an index of tracer for the estimation of secondary $PM_{10}$ at higher photochemical activity regimes. The results show that the estimated secondary $PM_{10}$ concentrations for moderate and high photochemical regimes are found to be 18.8% ($10.9\;{\mu}g/m^3$), and 35.0% ($26.2\;{\mu}g/m^3$), respectively. Diurnal variation of secondary $PM_{10}$ for the moderate photochemical regime shows weak but noticeable patterns. However, the highly activated photochemical regime shows strong diurnal variations of secondary $PM_{10}$ concentrations with the maximum value of $35.1\;{\mu}g/m^3$ at 1300LST.

• Journal of the Korean Solar Energy Society
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• v.36 no.4
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• pp.11-20
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• 2016

For accurate wind resource assessment and wind turbine performance test, it is essential to secure wind data covering a rotor plane of wind turbine including a hub height. In general, we can depict wind speed profile by extrapolating or interpolating the wind speed data measured from a meteorological tower where multiple anemometers are mounted at different heights using a power-law of wind speed profile. The most important parameter of a power-law equation is a vertical wind profile exponent which represents local characteristics of terrain and land cover. In this study, we calculated diurnal vertical wind profile exponents of 8 locations in Jeju Island who possesses excellent wind resource according to the GUM (Guide to the Expression of Uncertainty in Measurement) to evaluate its uncertainty. Expanded uncertainty is calculated by combined standard uncertainty, which is the result of composing type A standard uncertainty with type B standard uncertainty. Although pooled standard deviation should be considered to derive type A uncertainty, we used the standard deviation of vertical wind profile exponent of each day avoiding the difficult of uncertainty evaluation of diurnal wind profile variation. It is anticipated that the evaluated uncertainties of diurnal vertical wind profile exponents at 8 locations in Jeju Island are to be registered as a national standard reference data and widely used in the relevant areas.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.188-195
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• 2018

Time series analysis was conducted to identify the factors affecting short-term variation of water temperature in Wando. Spectrum analysis showed that air temperature peaks at diurnal period, while water temperature and tide level peak at both semi-diurnal and diurnal periods. Coherence between water temperature and the tide level presented 0.92 at semi-diurnal period. Numerical experiment were carried out to understand the spatio-temporal distribution of water temperature in the study area. Average water temperature difference between maximum ebb and flood was $0.3^{\circ}C$ in spring tide, but $0.13^{\circ}C$ in neap tide. The reason for the large difference in spring tide is that relatively cold water entered with strong tidal currents at flood tide and flowed out at ebb tide. Water temperature on coasts was higher than out at sea. This is because the depth in the coast is shallower than at sea, and water temperature increases rapidly due to solar radiation.

• Journal of Astronomy and Space Sciences
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• v.23 no.2
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• pp.117-126
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• 2006

The Diurnal variation of galactic cosmic ray (GCR) flux intensity observed by the ground Neutron Monitor (NM) shows a sinusoidal pattern with the amplitude of $1{\sim}2%$ of daily mean. We carried out a statistical study on tendencies of the local times of GCR intensity daily maximum aad minimum. To test the influences of the solar activity and the location (cut-off rigidity) on the distribution in the local times of maximum and minimum GCR intensity, we have examined the data of 1996 (solar minimum) and 2000 (solar maximum) at the low-latitude Haleakala (latitude: 20.72 N, cut-off rigidity: 12.91 GeV) and the high-latitude Oulu (latitude: 65.05 N, cut-off rigidity: 0.81 GeV) NM stations. The most frequent local times of the GCR intensity daily maximum and minimum come later about $2{\sim}3$ hours in the solar activity maximum year 2000 than in the solar activity minimum you 1996. Oulu NM station whose cut-off rigidity is smaller has the most frequent local times of the GCR intensity maximum and minimum later by $2{\sim}3$ hours from those of Haleakala station. This feature is more evident at the solar maximum. The phase of the daily variation in GCR is dependent upon the interplanetary magnetic field varying with the solar activity and the cut-off rigidity varying with the geographic latitude.

• Journal of Astronomy and Space Sciences
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• v.37 no.3
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• pp.165-170
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• 2020

Muons and neutrons are representative secondary particles that are generated by interactions between primary cosmic ray particles (mostly protons) and the nuclei of atmospheric gas compounds. Previous studies reported that muons experience seasonal variations because of the meteorological effects of temperature. The intensity of neutrons has a typical modulation with various periods and reasons, such as diurnal and solar variation or transient events. This paper reports that cosmic ray particles, which were observed by neutron monitors, have seasonal variations using the daily data at the Oulu neutron monitor. To eliminate the effects of solar activity across time, the daily data were normalized by two different transformations: transformations with respect to the grand mean and yearly mean. The data after transformation with respect to the yearly mean showed more statistical stability and clear seasonal variations. On the other hand, it is difficult to determine if the seasonal variation results from terrestrial effects, such as meteorological factors, or extraterrestrial effects, such as the position of the Earth in its orbit of revolution.

• The Korean Journal of Pharmacology
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• v.20 no.2
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• pp.35-47
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• 1984

Contents of immunoreactive ${\beta}-endorphin$ and maximum of $^3H-morphine$ binding was measured in the rat midbrain homogenates from different subgroups at 24 hour interval over 24 hours. Animals were adapted to the light-dark cycle(L : D, 12: 12) or constant darkness (D : D, 12 : 12) for 3 weeks. After the adaptation, 0.5ml of physiologic saline or drug was administered twice a day for 2 weeks. A highly significant circadian rhythm with the peak$(94.8{\pm}7.7\;fmole/mg\;protein)$ at 06:00 and the nadir $(27.6{\pm}2.4\;fmole/mg\;protein)$ at 18:00 was observed in constant of group. Constant dark or treatment of reserpine, pargyline, imipramine, amphetamine and chlorpromazine modified the diurnal rhythm in the time of peak and nadir, shape, phase amplitude and 24 hour mean of ${\beta}-endorphin$ contents. Opiate receptor binding by $^3H-morphine$ also showed highly significant diurnal change in control and constant dark adapted rats. Statistical analysis by one-way analysis of variance and two-way analysis of variance indicates that the·re are highly significant differences between the diurnal change of ${\beta}-endorphin$ in control and those constant dark adapted and drug treated groups. However diurnal change of Maximum $^3H-morphine$ binding is closely related to the change of ${\beta}-endorphin$ contents. The results are interpreted with regard to the circadian rhythm of beta-endorphin contents, its modification by psychoactive drugs and possible mechanism of diurnal change of opiate receptor in brain.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.1
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• pp.55-63
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• 2016

Temperature lapse rate within the planetary boundary layer shows a diurnal cycle with a substantial variation. The widely-used lapse rate value for the standard atmosphere may result in unaffordable errors if used in interpolating hourly temperature in complex terrain. We propose a simple method for estimating hourly lapse rate and evaluate whether this scheme is better than the conventional method using the standard lapse rate. A standard curve for lapse rate based on the diurnal course of temperature was drawn using upper air temperature for 1000hPa and 925hPa standard pressure levels. It was modulated by the hourly sky condition (amount of clouds). In order to test the reliability of this method, hourly lapse rates for the 500-600m layer over Daegwallyeong site were estimated by this method and compared with the measured values by an ultrasonic temperature profiler. Results showed the mean error $-0.0001^{\circ}C/m$ and the root mean square error $0.0024^{\circ}C/m$ for this vertical profile experiment. An additional experiment was carried out to test if this method is applicable for the mountain slope lapse rate. Hourly lapse rates for the 313-401m slope range in a complex watershed ('Hadong Watermark 2') were estimated by this method and compared with the observations. We found this method useful in describing diurnal cycle and variation of the mountain slope lapse rate over a complex terrain despite larger error compared with the vertical profile experiment.

• Korean Journal of Agricultural and Forest Meteorology
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• v.26 no.3
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• pp.199-207
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• 2024

Measuring and estimating methane (CH₄) emissions accurately is important in rice paddy field. For reliable estimation, diurnal and seasonal variations of methane must be tracked, and measured frequently. The closed chamber method proposed according to the IPCC guidelines is relatively cheap and easy to move, so it is widely used, but it is difficult to estimate accurate methane emissions due to spatiotemporal constraints such as sampling time and number of measuring times. In this paper, the diurnal variation pattern was analyzed by measuring methane emissions four times at two-hour intervals throughout the day during the rice growth stage. When the emissions for each time period were converted to a daily time-weighted average, the diurnal average methane flux appeared in the time periods of 8:00~12:00 and 16:00~20:00. Through our results, we hope to provide useful information about determining reasonable times of methane measurement to researchers who measure methane emissions in rice paddy fields using the closed chamber method in the future.