• Journal of the Korean Geographical Society
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• v.41 no.3 s.114
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• pp.361-372
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• 2006

The purpose of this paper is to analyze temporal trends and spatial distribution of frost occurrence days using 54 weather stations under the Korea Meteorological Administration during the recent 30years ($1971{\sim}2000$). The frost occurrence days in the middle inland area was more than in the coastal area, but the period of free-frost days in the coastal area was longer than that in the middle inland. In the southern and eastern coastal areas, the frost day was more than in the western coastal area. The distribution of the first frost day was similar to that of the last frost day. The first frost day in the coastal area appeared a month later than that in the middle inland. The last frost day in the coastal area appeared $20{\sim}25$ days later than that in the middle inland. At most of stations which the first frost day was getting delayed and the last frost day earlier, the frost occurrence days showed a decreasing trend. However, in some stations, the frost occurrence day was increasing. As the frost days in October, March and April at some stations showed an increasing trend, the damage due to the frost might be increased in some areas in South Korea.

• The Korean Journal of Physiology
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• v.8 no.1
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• pp.15-22
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• 1974

The influence, upon male rat's mating behavior, of Korean Panax Ginseng administered for 3 and 5 days was investigated by direct behavioral observation and also by counting the number of copulation plugs the animals deposited. Four쇼-four male albino rats were used. Part of the animals received ginseng for 3 days (ginseng-3 day group, N= 12) or for 5 days(ginseng-5 day group, H=10), while the remaining animals received saline for 3 days (saline-3 day group, N=12) or for 5 days (saline-S day group, N=10). Each animal belonging to the 2 ginseng groups received subcutaneously 0.5 ml/100 g body weight of ginseng alcohol extract solution (4 mg of the ethyl alcohol extract in 1 ml of physiological saline), and each rat belonging to the 2 saline groups received the same amount of saline per day. During the dark period of the light-dark cycle on the next day following the last drug administration, a female rat in the artificial estrus was introduced to each male and the mating behavior was observed for 45 minutes. The observation session was divided into two parts and, in the early part which terminated with the first ejaculation and succeeding intromission, following behavioral measures were taken: mounting latency, intromission latency, inter-intromission period, ejaculatory latency(time from the first intromission until the first ejaculation), occurrence of mounting with intromission, occurrence of mounting without intromission, and postejaculatory interval. Behavioral measures taken in the later part of the session after the first ejaculation were: occurrence of mounting with intromission, occurrence of mounting without intromission, and occurrence of ejaculation. Immediately after the behavioral observation session the experiment turned to measure, for 10 days, the number of copulation plug which each pair of rats deposited. Following results were obtained: 1. After several mountings mounting with intromission, males of the 2 ginseng groups finished the first ejaculation significantly earlier than the corresponding 2 saline groups did. 2. The postejaculatory latency was significantly reduced in the ginseng-5 day group compare with the value of the saline-5 day group and also compared with the value of the ginseng-3 day group. 3. The 2 ginseng groups ejaculated significantly more often in 45 minutes' observation session than the corresponding 2 saline groups did. 4. The number of copulation plug deposited in 10 days by the animals of the 2 ginseng groups. significantly exceeded the number deposited by the corresponding 2 saline group animals. The animals of the ginseng-5 day group deposited copulation plugs significantly more than the animals of the ginseng-3 day group did. It is inferred from the above results that the ginseng facilitates mating behavior of male rats, and that the degree of facilitation may be influenced by the duration of drug administration.

• Journal of the Korean Geographical Society
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• v.40 no.3 s.108
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• pp.285-295
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• 2005

This paper was examined distribution and changing trends on occurrence days of Spring Cold(cold surge in the flowering season) from the end of February to early in April during 1973-2004. We defined an occurrence day of Spring Colds as above $10\%$ of the anomalies of mean daily temperature or above $10\%$ of the difference of the daily mean temperature between the day before two days. In the west coastal region, the occurrence days of Spring Colds is higher in the end of February and less frequent in the early in April. In the east coastal region, the occurrence days of Spring Colds is higher in the early in April. Spring Colds is closely related with frequencies and a intensities of Siberian High. The occurrence days of Spring Colds has decreased in the most area except Ulleung island and the east coastal region.

• Journal of Korean Society of Forest Science
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• v.95 no.2
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• pp.160-167
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• 2006

Most of the forest fires that occur in South Korea are caused by human. We partitioned South Korea into nine districts and used observed weather data and daily fire occurrence records for the 1994 to 2003 period to develop a human-caused fire occurrence model of South Korea. Logistic regression analysis techniques were used to relate the probability of a fire day to Fine Fuel Moisture Code (FFMC) component of the Canadian Forest Fire Danger Rating System. The probability of the number of fire day was increased as FFMC increased in the nine districts of South Korea.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.38.3-39
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• 2009

Equatorial Plasma Bubble (herafter, EPB) is a common feature in low-latitude F-region during the night time. Since EPB causes significant impacts on the satellite communication and navigation systems, its accurate forecast is highly demanded by the GNSS users. Thus, further understanding of these features and their configuration is a challenging issue in space weather studies. The day-to-day variability of the plasma bubble activity was investigated by analyzing the TIMED/GUVI, ROCSAT-1, DMSP, and CHAMP satellite data. The pre-reversal enhancement (PRE) is known as the most important single parameter for the onset of plasma bubbles but we do not know yet to what extent the day-to-day variability of the bubble activity can be attributed to the PRE. We obtained the magnitude of the PRE from ROCSAT-1 and the occurrence of bubbles in relation to the PRE was investigated by using the coincident observations of EPBs from TIMED/GUVI, DMSP, and CHAMP. By conducting one-to-one comparison of the PRE characteristics with the EPB occurrence we examined the role of the PRE in the onset of EPBs.

• Journal of The Korean Society of Emergency Medicine
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• v.29 no.6
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• pp.603-615
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• 2018

Objective: We analyzed the association between regional weather and temporal changes on the daily occurrence of trauma emergencies and their severity. Methods: In this cross-sectional prospective study, we investigated daily atmospheric patterns in trauma episodes in 1,344 patients in Cheongju city, South Korea, from January 2016 to December 2016 and analyzed the association of trauma occurrence and Injury Severity Scores (ISS) with weather conditions on a daily scale. Results: The mean age of trauma patients was $53.0{\pm}23.8years$ and average ISS was $9.0{\pm}2.0$. Incidence of trauma was positively correlated with average temperature (r=0.512, P<0.001) and atmospheric pressure (r=0.332, P=0.010) and negatively correlated with air pollutants (particulate matter less than $2.5{\mu}m^3$ [PM2.5], r=-0.629, P<0.001; particulate matter less than $10{\mu}m^3$ [PM10], r=-0.679, P<0.001). ISS was not significantly correlated with climate parameters and air pollutants, and variability was observed in the frequency and severity of trauma by time of day (highest occurrence, 16-20 pm; highest ISS, 4-8 am), day of the week (highest occurrence and highest ISS, Saturday), month of the year (highest occurrence, July; highest ISS, November), and season (highest incidence, summer; highest ISS, autumn). Conclusion: The study shows a positive relationship between trauma occurrence and specific weather conditions, such as atmospheric temperature and pressure. There was a negative relationship between concentrations of PM2.5 or PM10, and trauma occurrence. However, no correlation was observed between weather conditions or the concentrations of air pollutants and ISS. In addition, seasonal, circaseptan, and circadian variations exist in trauma occurrence and severity. Thus, we suggest that evaluation of a larger, population-based data set is needed to further investigate and confirm these relationships.

• Asian Journal of Turfgrass Science
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• v.13 no.2
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• pp.79-90
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• 1999

This study was conducted to provide basic understandings for proper management of zoysiagrass fairways. Mowing intervals of 2, 4 and 6-days, with and without aeration were compared at two fertility levels. Turfgrass quality, growth and pest infestation were evaluated. Turf density, number of tillers, leaf width and resiliency were significantly affected by mowing frequency. Turfgrass plots mowed every 2-day had greater density, tillering, and resiliency but had narrower leaf width compared to other mowing treatments. Clipping dry weight with every 2-day mowing increased in the early stage of mowing treatment regardless of fertilizer application rates but gradually decreased in the later stage of mowing treatment compared to every 4 or 6-day mowings. The dry weight of above-ground part was not affected by mowing frequency, but that of underground part was significantly higher for every 6-day mowing frequency(3.3kg/day/m2) compared to every 2 or 4-day mowings. The organic mater content in soil was not different among mowing treatments but it was significantly reduced by the core aerification treatment, indicating significant effect of core aerification on thatch decomposition. Occurrences of weeds such as annual bluegrass and crabgrass according to mowing frequency were greater in every 2-day mowing treatment, while plots mowed every 6 days had less weed occurrence. Occurrence of rusts significantly increased in high fertility plots and frequently mowed turfgrasses.

• Korean journal of applied entomology
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• v.29 no.2
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• pp.104-112
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• 1990

Studies were conducted to investigate hosts, life cycle, population dynamics and natural enemies of mulberry scale, Pseudaulacaspis pentagona Ta. & Tozz., from 1987 to 1988 in southern region of Korea. The host plants were 22 families and 74 species. Host plants belonged to genus Prunus in general were severely damaged due to mulberry scale. Mulberry scale was most likely to have three generations a year with first occurrence of larval stage from mid-May to late June, second occurrence from mid-July to mid-August and third occurrence from early September to late October including 3 peaks in early and mid-June, late July and mid-September. In case of each stage occurrence, eggs were peaked on 10th day, larvae on 25th day and adults on 7th day from beginning of occurrence, respectively. Natural enemies were observed as parasitoids of 3 species such as Aphytis diaspidis, Archenomus orientalis and Apterencyrtus mocrophagus and as predators of 3 species such as Chilocorus Kuwanae, Chilocorus rubidus and Hormonia axyridis. Shoot growth was affected by mulberry scale and Lepra to dwindle as much as half of normal growth.

• Journal of Environmental Science International
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• v.26 no.6
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• pp.751-765
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• 2017

This research investigates the characteristics of meteorological variation and fine particles ($PM_{10}$ and $PM_{2.5}$) for case related to the haze occurrence (Asian dust, long range transport, stationary) in Busan. Haze occurrence day was 559 days for 20 years (from 1996 to 2015), haze occurrence frequency was 82 days (14.7%) in March, followed by 67 days (12.0%) in February and 56 days (10.0%) in May. Asian dust occurred most frequently in spring and least in winter, whereas haze occurrence frequency was 31.5% in spring, 29.7% in winter, 21.1% in fall, and 17.7% in summer. $PM_{10}$ concentration was highest in the occurrence of Asian dust, followed by haze and haze + mist, whereas $PM_{2.5}$ concentration was highest in the occurrence of haze. These results indicate that understanding the relation between meteorological phenomena and fine particle concentration can provide insight into establishing a strategy to control urban air quality.

• Journal of Environmental Science International
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• v.6 no.2
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• pp.95-106
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• 1997

The characteristics on the transtion probabilities and periodicity for the daily precipitation occurrence in Korean peninsula are investigated by applying the Markov chain properties to daily precipitation occurrence. In order to examine the responses of Markov Chain properties to the applied period and their magnitudes, three cases (Case A: 1956~ 1985 at 14 stations, Case B: 1965~ 1994 at 14 stations, and Case C: 1985~ 1994 at 63 stations) are considered In this study. The transition probabilities from wet day to wet day for all cases are about 0.50 and in summer, especially July, are higher. In addition, considering them in each station we can find that they are the highest at Ullung-do and lowest at Inchon for all cases. The annual equilibrium probabilities of a wet day appear 0.31 In Case A, 0.30 Case B, and 0. 29 Case C, respectively. This may explain that as the data-period used becomes shorter, the higher the equilibrium probability is. The seasonal distributions of equilibrium probabilities are appeared the lowest(0.23~0.28) in winter and the highest(more than 0.39) in spring and monthly in .truly and in October, repectively. The annual mean wet duration for all cases is 2.04 days in Case A, 1.99 Case B, and 1.89 Case C, repectively. The weather cycle obtained from the annual mean wet and dry duration is 6.54~6.59 days, which are closely associated with the movement of synoptic systems. And the statistical tests show that the transitions of daily precipitation occurrence for all cases may have two-state first Markov chain property, being the stationarity in time and heterogeneity in space.