• 한국환경과학회지
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• 제9권6호
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• pp.475-482
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• 2000

The purpose of this study is to find out the temporal and spatial characteristics of the diurnal wind variation between coastal and inland areas using the hourly wind data of 58 AWS-stations in the South Korea which are collected during the 10 years from 1980. Diurnal variation is investigated by using the Fast Fourier Transform(FFT), and the wind direction in investigated by comparing C(sub)r with C(sub)v represented the constancy of wind. For the scalar wind speed, the maximum wind speed occurs in the daytime 14h to 16h. The maximum diurnal amplitude at coastal areas occurs from 12h to 16h, and is about 2 hours faster than that at inland areas. Vector mean wind speed is strong at coastal areas and Chupungnyong, Kumi, Taegu of inland areas. The diurnal variation ellipses make a right angle with coastline show that the land and sea breezes are prevailing. The constancy of wind is strong at all observations in January. In the relationship between $C_r and C_v, C_v is higher than C_r$.

• 수면정신생리
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• 제8권1호
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• pp.30-36
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• 2001

배 경 : 주간기분변동은 주요 우울장애, 멜랑콜리아 형의 세부진단으로 포함되어 있다. 그러나 현재까지의 연구를 종합해 보면 주간기분변동은 우울증의 고유한 증상인지 수면 양상의 변화와 관련된 현상인지, 혹은 별개의 다른 기전을 갖는 현상인지에 대해서 서로 모순되는 주장들이 혼재되어 있다. 이에 본 연구에서는 우울증의 세부 진단에 따른 주간 기분변동의 유무를 조사하고, 주간기분변동의 유무에 따른 수면 양상의 차이를 비교함으로써 주간기분변동과 수면 양상 사이의 관계를 찾아 보고자 하였다. 방 법 : 입원 혹은 의뢰된 우울장애 환자 62명을 대상으로 하여 주간기분변동은 Visual Analogue Mood Scale로, 수면 양상은 Pittsburgh Sleep Quality Index, 우울증의 심각도는 Hamilton Depression Rating Scale을 이용하여 측정하였다. 주간기분변동이 있는 군과 없는 군으로 나누고 HDRS 총점과 소항목, 그리고 PSQI 총점과 소항목을 변수로 하여 통계적 분석을 시행하였다. 결 과 : 주간기분변동의 빈도는 각각의 진단별로 차이가 없었으며, 주간기분변동이 있는 군과 없는 군으로 나누었을 때 중기 불면증과 수면 시간에 있어서 유의한 차이가 있었다(p<0.05). 또한 멜랑콜리아 형만을 대상으로 주간기분변동이 있는 군과 없는 군을 비교하였을 때 중기 불면증, 수면 시간뿐만 아니라 PSQI 총점, 수면 잠복기, 수면 장애, 주간의 기능 면에서 유의한 차이를 보였다(p<0.05). 결 론 : 주간기분변동은 멜랑콜리아 형의 우울장애 뿐만 아니라, 다른 우울장애에서도 존재하기 때문에 주간기분변동이 멜랑콜리아 형 우울장애의 특유한 증상으로 보기는 어려웠다. 주간기분변동이 있는 군에서 수면의 질이 더 좋은 것으로 나타났는데 이는 수면과 관련될 가능성이 높으며 향후 심도있는 연구가 필요할 것이다. 주간 기분변동은 외부 환경의 영향을 받기 쉬움으로 신뢰성을 높이기 위해서는 측정 기간과 횟수 등의 방법론적 연구도 필요할 것으로 생각된다.

• Journal of Astronomy and Space Sciences
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• 제35권4호
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• pp.219-225
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• 2018

Cosmic rays are ions that move at relativistic speeds. They generate secondary cosmic rays by successive collisions with atmospheric particles, and then, the secondary particles reach the ground. The secondary particles are mainly neutrons and muons, and the neutrons are observed by the ground neutron monitor. This study compared the diurnal variation in cosmic ray intensity obtained via harmonic analysis and that obtained through the pile-up method, which was examined in a previous study. In addition, we analyzed the maximum phase of the diurnal variation using four neutron monitors with a cutoff rigidity below approximately 6 GV, located at similar longitudes to the Oulu and Rome neutron monitors. Expanding the data of solar cycles 20-24, we examined the time of the maximum cosmic ray intensity, that is, the maximum phase regarding the solar cyclic modulation. During solar cycles 20-24, the maximum phase derived by harmonic analysis showed no significant difference with that derived by the pile-up method. Thus, the pile-up method, a relatively straightforward process to analyze diurnal variation, could replace the complex harmonic analysis. In addition, the maximum phase at six neutron monitors shows the 22-year cyclic variation very clearly. The maximum phase tends to appear earlier and increase the width of the variation in solar cycles as the cutoff rigidity increases.

• 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.

• 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.

• 한국대기환경학회지
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• 제14권2호
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• pp.153-160
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• 1998

The concentrations of volatile organic compounds (VOCs) in the atmosphere were measured from the Yochon Industrial Estate and compared with those from Tongkwangyang and Seoul. The first important phenomenon observed in the air of Yochon was high concentrations of alkenes and in particular, ethylene and propene. For most dominant species, their means and standard deviations were high simultaneously. Concentrations of several major aliphatic species exhibited a similar pattern of diurnal variation, however, with different species combination on each day. Concentrations of several hazardous aromatic species also exhibited a similar pattern of diurnal variation on the same day, which was different from that observed in the diurnal variation of major aliphatic species. It was interpreted that some species were intermittently released from relevant processes. It was also understood that high concentrations and variations of VOC species in Yochon were localized and not related to high average concentrations of ozone in Yochon and Tongkwangyang areas.

• 한국환경과학회지
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• 제8권1호
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• pp.33-43
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• 1999

This paper aims to describe the characteristics of air pollution using air pollutants concentration and meteorological data observed at Kimhae from December 1996 to November, 1997. The results are as follows : The concentration distribution of sulfur dioxide($SO_2$), carbon monoxide(CO), particulate matter(PM-10), and nitrogen dioxide($NO_2$) is high during the late fall and winter and low during the summer, but ozone concentration is low during the winter season and high during summer season except Jangma period and these distributions appear to be closely connected with insolation and the number of clear day. Diurnal variation of concentrations for sulfur dioxide, particulate matter, and carbon monoxide are high during the rush hours and nighttime and low during the daytime and these variations are distinct toward the winter season. And diurnal variation of nitrogen dioxide concentration has also same pattern and these patterns are closely related to the increasing traffic volume at rush hours. Diurnal variation of ozone concentration is generally increase for daytime and decrease for the late afternoon and are closely related to the insolation and photochemical reaction. The 24 hour average concentrations of air pollutant observed at Kimhae represented a positive correlation and a negative correlation for $O_3$ and also a negative correlation for the meteorological elements such as wind speed and cloud cover.

• Journal of Korean Biological Nursing Science
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• 제18권1호
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• pp.9-16
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• 2016

Purpose: The purpose of this exploratory study was to find a specific time of day with a stable cortisol level and to investigate the relationship between salivary cortisol and sleep. Methods: A total of 36 Korean female college students participated in the study. Salivary specimens were collected 6 times a day for 2 days in different stressful situations. Sleep characteristics were measured using an actigraph while salivary specimens were collected. Perceived stress was evaluated using the Global Assessment of Recent Stress. Results: Depending on whether there were morning peak and/or afternoon elevations in the cortisol levels, the type of diurnal cortisol pattern was classified into 4 types. None of the cortisol levels in different times of the day showed significant relationships to perceived stress levels. Cortisol levels in the morning, levels of peak cortisol and diurnal differences of cortisol were significantly correlated with sleep duration. The time with most stable cortisol level was 9-10 pm. Conclusion: It is recommended that measurements of salivary cortisol are taken from 9-10 pm since it showed a stable value regardless of diurnal cortisol rhythm and sleep. Sleep duration should be considered as an important confounding factor in measuring cortisol levels in the morning and the diurnal differences of cortisol.

• 지구물리와물리탐사
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• 제12권2호
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• pp.208-214
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• 2009

보은과 괴산에 위치한 GNSS상시관측소의 GNSS관측자료와 경사계자료를 이용하여, 1시간과 3시간 동안의 GNSS 차분벡터의 변위와 시간에 따른 차분 경사 벡터의 변위를 계산했다. 그리고, 시간에 따른 두 변위 사이의 관련성을 얻었다. 이렇게 계산된 관련성은 ‘높음‘보다는 낮았다. 그러나, 일사량의 일변화는 일어남이 확실하고, 측정 결과 안테나탑의 경사 변위 때문에 안테나 위상중심 위치의 회전 운동이 존재함이 확실하므로, 우리는 DGNSS에 있어서 보정 오차를 방송할 때와 가상기준국체계(VRS)에 있어서 상시관측소에서 측정된 자료를 방송할 때에 안테나 위상중심 위치의 일변화를 고려할 것을 제안한다.

• 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.