• 한국가축번식학회지
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• 제17권4호
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• pp.325-329
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• 1994

Seasonal and diurnal variation in serum testosterone was measured by radioimmunossary in 3 mature Korean native male goats. Blood was collected at 3-h intervals for 24h in each season. Mean levels of 4 seasons ranged from 0.82 to 2.06ng/ml and no difference was among seasons, although level in fall and winter was slightly higher. Diurnal level tended to increase at daytime in all season and when diurnal variation in level was compared to daily mean of each season, level of daytime greatly(P<0.05) increased in summer. However, variation between light and dark period in other seasons did not show significant difference. Daytime increase of testosterone was found 3 to 4 after dawn and level increased 1 to 2h ahead in summer and fall than that in others. These results in serum testosterone suggest that there was no great seasonal variation in endocrine function of goat testis.

• 한국대기환경학회지
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• 제19권2호
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• pp.231-245
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• 2003

Hourly PM$_{10}$ concentrations measured at 11 sites in Seoul and 10 sites in the large cities over South Korea for the period from March 1995 to February 2000 are analyzed to examine annual trend and monthly variations of the PM$_{10}$ concentrations. Further analysis has been carried out by using the one year data from March 1999 to February 2000 to see the seasonal variation, diurnal variation and weekly variation of the seasonally averaged PM$_{10}$ concentrations at each site. Weekly variations of the CO concentrations at the same sites for the same one year period are compared with that of the PM$_{10}$ concentration. There is no significant annual trend in the variation of the PM$_{10}$ concentration at all the sites analyzed. The seasonal and monthly mean concentrations show a minimum concentration in summer and alternative maximum concentration in spring and winter for most sites. The diurnal variation of the seasonally averaged mean PM$_{10}$ concentrations is strongly affected by traffic loads and meteorological conditions. The weekly variation of seasonal averaged concentrations of CO and PM$_{10}$ shows a high concentration for weekdays in spring, autumn and winter while high concentration for weekends in summer.nds in summer.

• Journal of Positioning, Navigation, and Timing
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• 제5권2호
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• pp.87-96
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• 2016

The ionospheric error, which is one of many error elements considered during the Global Navigation Satellite System (GNSS) positioning, is hard to be predicted due to the influence of geomagnetic activity and irregular solar activities. Thus, the present study analyzed a change pattern in the ionosphere through Global Ionosphere Map (GIM) data for 12 years from 2003 to 2014 and a variation in the Slant Total Electron Content (STEC) between Sinuiju and Busan which was the longest range in the southeastern direction of the Korean Peninsula. The variation in the STEC verified the diurnal, annual, and solar cycle variations due to the influence of solar activity. The diurnal variation was characterized that the variation in the STEC started to increase from 6-7 am and reached the maximum at 13-14 pm followed by being decreased. The seasonal variation was characterized that the variation in the STEC was high in spring and autumn whereas it was low in summer and winter. The solar cycle variation revealed that the variation in the STEC increased during solar maximum and decreased during solar minimum. The variation in the STEC was up to 20 Total Electron Content Unit (TECU) during the solar minimum and up to 60 TECU during solar maximum.

• 한국대기환경학회지
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• 제19권3호
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• pp.285-296
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• 2003

The measurement of the radiation energy, trunk temperature, leaf area index (LAI), air temperature, vapor pres-sure, and precipitation has been conducted under a mixed forest at Kwangneung Arboretum during the period of 2001. Characteristics of the diurnal and seasonal variation of the radiative energy were investigated. The aerodynamic roughness length was determined as about 1.6 m and the mean albedo was about 0.1 The downward short-wave radiation was linearly correlated with the net radiation and its correlation coefficient was about 0.96. From this linear relation, the heating coefficient was calculated and its annual mean value was about 0.21 The albedo and heating coefficient was varied with season, surface characteristics, and meteorological conditions. The diurnal and seasonal variations of radiation energy were discussed in terms of the surface characteristics and meteorological conditions. In the daytime, during clear skies, net radiation was dominated by the shortwave radiation. In presence of clouds and fog, the radiation energy was diminished. At night, the net radiation was entirely dominated due to the net longwave radiation. There was no distinct diurnal variation in net radiation flux during the overcast or rainy days. The net radiation was strongest in spring and weakest in winter. The seasonal development in leaf area was also reflected in a strong seasonal pattern of the radiation energy balance. The timing, duration, and maximum leaf area and trunk temperature were found to be an important control on radiation energy budget. The trunk temperature was either equal or warmer than air temperature during most of the growing season because the canopy could absorb a substantial amount of sunlight. After autumn (after the middle of October), the trunk temperature was consistently cooler than air temperature.

• Journal of Astronomy and Space Sciences
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• 제37권3호
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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.

• Journal of Astronomy and Space Sciences
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• 제30권3호
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• pp.175-178
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• 2013

Recently, two instruments of cosmic ray are operating in South Korea. One is Seoul muon detector after October 1999 and the other is Daejeon neutron monitor (Kang et al. 2012) after October 2011. The former consists of four small plastic scintillators and the latter is the standard 18 NM 64 type. In this report, we introduce the characteristics of both instruments. We also analyze the flux variations of cosmic ray such as diurnal variation and Forbush decrease. As the result, the muon flux shows the typical seasonal and diurnal variations. The neutron flux also shows the diurnal variation. The phase which shows the maximum flux in the diurnal variation is around 13-14 local time. We found a Forbush decrease on 7 March 2012 by both instruments. It is also identified by Nagoya multi-direction muon telescope and Oulu neutron monitor. The observation of cosmic ray at Jangbogo station as well as in Korean peninsula can support the important information on space weather in local area. It can also enhance the status of Korea in the international community of cosmic ray experiments.

• 한국환경과학회지
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• 제8권3호
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• pp.281-286
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• 1999

This study was conduced to examine the monthly and seasonal variation of $SO_2$, TSP, $O_3$ concentration in Dongsamdong, Pusan coastal area. And the characteristics of air pollution of this area was compared to Kwangbokdong in Pusan and Taehadong in Ullungdo. Monthly mean concentration of $SO_2$ and TSP showed lower than Kwangbokdong, $O_3$ was higher than Kwangbokdong. In case of $SO_2$, seasonal variation of Dongsamdong was remarkabler thn Kwangbokdong and the concentration difference of early morning and daytime was higher than Kwangbokdong. Taehadong showed very lower concentration as background area. In case of TSP, Dongsamdong was lower concentration and smaller diurnal change than Kwangbokdong, Taehadong showed very lower concentration as backgound area. In case of $O_3$, Dongsamdong was 10ppb higher than Kwangbokdong at daytime maximum concentration, diurnal change of concentration was higher, too. In case of frequency distribution of concentration, $SO_2$, and TSP at Dongsamdong showed higher frequency in low concentration class and $O_3$ showed in high concentration class as compared with Kwangbokdong.

• Journal of Astronomy and Space Sciences
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• 제38권4호
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• pp.229-236
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• 2021

We present for the first time the characteristics of upper atmospheric horizontal winds over the Korean Peninsula. Winds and their variability are derived using four-year measurements by the Korea Astronomy and Space Science Institute (KASI) meteor radar. A general characteristic of zonal and meridional winds is that they exhibit distinct diurnal and seasonal variations. Their changes indicate sometimes similar or sometimes different periodicities. Both winds are characterized by either semi-diurnal tides (12 hour period) and/or diurnal tides (24 hour period) from 80-100 km. In terms of annual change, the annual variation is the strongest component in both winds, but semi-annual and ter-annual variations are only detected in zonal winds.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제22권1호
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• pp.24-32
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• 1994

A special upper-air observation including airsonde and pibal observations was performed to investigate the characteristics features of the vertical distribution of the meteorological elements over Taegu on a selected clear day of each season from October 1991 to August 1992. The diurnal and seasonal variations of the vertical profiles of air temperature and mixing ratio were obtained from airsonde observations and wind speed and direction from pibal observations. The results of these special upper-air observations are as follow : The diurnal variation of the vertical distribution of air temperature reveals the characteristic features associated with the atmospheric boundary layer. All case days, except for the summer season, show upper-level inversion layer which influenced by surface high, and surface inversion layer produced by radiative cooling. The diurnal variation of mixing ratio shows the maximum vale at 1500 LST in both the upper and low levels, and is larger on the lower level than the upper level. The mixing ratio of the lower level is larger than that of the upper level. On the average the mixing ratio decrease with the height, and is the wettest on the summer case day and the driest on the winter case day. The diurnal variation of the wind velocity and direction are variable in the lower level with time and height, while they are steady in the upper level. On the average, the wind direction is southerly or southeasterly for the summer case day, westerly or northwesterly for the spring and fall case days, and northerly or northwesterly for the winter case day.

• 한국대기환경학회지
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• 제18권1호
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• pp.11-23
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• 2002

The concentrations of aldehydes were measured in downtown area of Buchun and Kwanghwamoon of Seoul from October 1997 to August 1998 using 2-series impingers. The data have been analysed to identify the seasonal pattern of aldehyde sources in metropolitan areas. The measured concentration (in ppbv) of aldehydes were 8.86 $\pm$ 7.28 HCHO (formaldehyde) and 7.79$\pm$7.29 $CH_3$CHO (acetaldehyde) in Buchun, while recording 10.13$\pm$8.58 (HCHO) and 7.64$\pm$6.65 ($CH_3$CHO) in Kwanghwamoon. Their diurnal variation patterns showed significant increase of HCHO and $CH_3$CHO concentration in early afternoon, indicating an increase in secondary sources. Their concentrations however decreased in the nighttime, regardless of seasons. The strength of correlations between certain pairs such as (1) HCHO and CO and (2) $CH_3$CHO and CO were generally high during the winter months (0.64< r < 0.84), suggesting the possibility of similar source processes for HCHO, $CH_3$CHO and CO. On the other hand during the summer months, their correlations are frequently lower than winter months. We suggested that the complexity of source/sink processes during the summer period may reduce the correlations between aldehyde and CO.