• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.479-483
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• 2004

A new calculation method of expected overtopping probability of rubble mound breakwater considering real tide occurrence has been proposed. A calculation method of expected overtopping probability of rubble mound breakwater was proposed by Kweon and Suh (2003). In their calculation, the fluctuation of tidal elevation was expressed by the sinusoidal change that yields the uniform distribution of occurrence frequency. However, the realistic distribution of tidal elevation should influence on the overtopping chance. In this study, the occurrence frequency of tidal elevation obtained from the real sea is included. The tidal elevation used in this study is collected from the east coastal part of Korean peninsular. Analyzing the annual data of the tidal fluctuation measured hourly during 355 days, the distribution of occurrence frequency is formulated utilizing by the normal distribution with one peak. Among the calculation procedures of annual maximum wave height, wave height-period joint distribution, wave run-up height and occurrence frequency of tide, only the annual maximum wave height is again chosen randomly from normal distribution to consider the uncertainty. The others are treated by utilizing the distribution function or relationship itself, It is found that the inclusion of the variability of tidal elevation has great influence on the computation of the expected overtopping probability of rubble mound breakwater. The bigger standard deviation of occurrence frequency is, the lower the overtopping probability of rubble mound breakwater is.

• 한국환경과학회지
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• 제8권3호
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• pp.287-292
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• 1999

This study was performed to investigate the characteristics of nocturnal maxiumu ozone occurrence and the meteorological relevance using to hourly ozone data and meteorological data for 1995~1996 in Pusan coastal area. Kwangbokdong showed the highest occurrence of nocturnal maximum ozone as 36.9%, and Deokcheondong showed the lowest occurrence(9.2%) for research period in Pusan. The occurrence rates of nocturnal maximum ozone concentration were decreased toward land area. The low maximum temperature, high minimum temperature, low diurnal range, high relative humidity, high wind speed, high could amount, low sunshine and low radiation were closely related to the main meteorological characteristics occuring the nocturnal maximum concnetration of ozone. It was shown that normal daily variation of ozone concentration by strong photochemical reaction at the before day of nocturnal maximum ozone. The concnetration of nocturnal maximum ozone were occured by entrainment of ozone from the upper layer of developed mixing layer. There are no ozone sources near the ground at night, so that the nighttime ozone should be entrained from the upper layer by forced convection.

• 한국대기환경학회지
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• 제14권4호
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• pp.379-385
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• 1998

The Holzworth's method was applied to estimate the daily maximum mixing height (DMMH) in Pohang, Osan and Kwangju areas. The data-base were established with meteorological data collected at air bases in these areas during the period 1983∼1992. It was investigated the seasonality, monthly trends and occurrence frequencies of the estimated DMMH data in each area. The estimated mean DMMH were found in the range of 1,100 m (winter) to 1,450m (spring). These mean DMMH data showed a typical seasonality in which higher values are commonly seen during spring and fall, while lower values during summer and winter seasons. An occurrence of estimated mean DMMH which in the range of 1,000∼2,000m altitude was appeared to be about 60%.

• International Journal of Industrial Entomology and Biomaterials
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• 제11권2호
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• pp.129-133
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• 2005

The seasonal occurrence and influence of abiotic factors viz., maximum and minimum temperature, maximum and minimum humidity and rainfall on population fluctuation of aleyrodid, Dialeuropora decempuncta on a evolved mulberry (Morus alba L.) variety known to be susceptible to aleyrodid infestation was assessed during the period from 1999 - 2001 in twenty-five villages under nine blocks of Malda district of West Bengal. The results indicate that the aleyrodid population is practically very low or absent during January to June and thereafter increases gradually. The increase in population of various stages of aleyrodid is significantly correlated with increase in previous 7 days of average maximum relative humidity.

• 한국응용곤충학회지
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• 제27권2호
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• pp.117-124
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• 1988

미곡지대인 전남지방에 분포된 미곡저장해충의 분류 및 주요해충들의 발생최성기간 및 발생소장을 조사한 바 다음과 같은 결과를 얻었다. 한국 남부 도작지대에 분포된 미곡저장해충은 Lepidoptera 8종, Coleoptera 10종, Orthoptera 1종, Thysanura 1종, Blattaria 2종, Hymenoptera 1종, Mites 2종이 동정되었으며 이중 발생량이 많고 피해가 큰 해충은 나비목의 보리나방(Sitotroga cereallella), 줄알락명나방(Cadra cautella), 한점쌀명나방(Paralipsa gullaris), 화랑곡나방(Plodia interpunctella), 딱정벌레목의 살바구미(Sitophilus oryzae), 톱가슴머리대장(Oryzaephilus sruinamensis), 갈생머리대장(Cryptolestes ferruineus), 거짓살도둑(Tribilium castaneum), 쌀도둑(Tenebroidesm uritanicus), 애수시렁이(Attagenus japonicus)가 바퀴목의 바퀴(Blattella germanica) 응애목의 가루응애(Acarus siro), 보리응애(Petrobia latens)등이었다. 본조사에서 이제까지 문제화되지 않았던 바퀴가 남부해안지대를 중심으로 많이 분포되었고 발생량도 많고 가충기간도 긴 편이었다. 분포지역도 넓고 발생량 및 피해가 큰 주요해충의 발생최성기간을 보면 보리나방 6월하순-7월중순, 한점쌀명나방 6월중~7워랑순, 화랑곡나방 7월중순~8월상순, 쌀바구미 7월하순~8월하순, 톱가슴머리대장 5월하순~6월중순, 거짓쌀도둑 7월중~8월중순, 쌀도둑 7월중~8월중순, 애수시렁이 6월중~7월상순, 바퀴 6월중~9월하순, 가루응애 및 보리응애 4월말~5월말경이었다. 쌀구미는 년 4세대를 거쳤으며 제1세대 5월중~6월상순, 제 2세대 7월중~하순, 제 3세대 8월중~하순, 제 4세대 10월중~11월상순이었고 톱가슴머리대장은 년 3세대를 거쳤으며 제 1세대는 5월중~6월상순, 제2세대는 8월상~하순, 제 3세대는 10월상~하순경이었다.

• Ocean and Polar Research
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• 제35권3호
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• pp.205-217
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• 2013

We investigated the population dynamics of Aurelia aurita in Sihwa Lake from April to October in 2009. Salinity ranged from 5.9 to 30.7 psu at the surface. Abundance of mesozooplankton ranged from 3 to 111,874 indiv. $m^{-3}$. Ephyrae occurred from April to May with the peak in abundance occurring on 17 April. Maximum density of ephyrae was observed near the power transmission towers that are known to be habitats of polyps. Mortality of ephyrae was lower than in other areas because of the abundant prey concentration and the absence of predators. Young medusae occurred from April to July with the peak in abundance occurring on 8 May. Adult medusae occurred from May to July with the peak in abundance on 25 June and they disappeared before the rainy season. Planula occurred only in May and June with the peak in abundance on 25 June. Growth rates of Aurelia aurita ranged from -0.06 to 0.34 $d^{-1}$, and decreased rapidly after May. The period in which adult medusa occurred was restricted, compared with those in other area in Korea (e.g., Masan Bay) and Japan (e.g., Tokyo Bay). In the period of this study, the available food was limited in June and salinity decreased to ca. 20 psu in May because of the beginning of the wet season. We assumed that the exceptionally short period of occurrence of the medusa may be a response of adults to changes in temperature, salinity or food limitation which leads to the precocious maturation of young medusa and the release of planula and that the brief occurrence of medusa was caused by an abrupt decrease in activity after the release of planula.

• 대기
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• 제21권4호
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• pp.361-371
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• 2011

In this study, characteristics and trends of tropical night (TN) are investigated by using the KMA 14 observation data for the recent 50 years (1958-2007) over South Korea. The TN is defined as a day with a daily minimum temperature exceeds the absolute threshold temperature ($25^{\circ}C$), and the relative deviation from normal temperature, 95th percentile of all observed daily minimum temperature. Although the spatial distribution of TN occurrence depends on the choice of the definitions, the frequency of TN shows strong spatial and interannual variations with the minimum at high land area (Chupungnyeong and wet years) and maximum at southern coastal area and large city area (Jeju, Busan, Seoul, Daegu). Most of TN occurs in August (56%) and July (41%), and the duration date of TN is proportional to the frequency of TN without regard to the definition method. In general, increasing trends are found in the TN time series without regard to the analysis method, but the trends are clearly depending on the analysis period and geographic locations. Decreasing trends are prominent during the most of analysis period, especially until the mid of 1990, whereas strong increasing trends are found during recent 30 years (1988-2007), especially at Jeju, Ulsan, Daegu and Pohang. Also the severity of TN is significantly increased in recent years.

• Journal of Astronomy and Space Sciences
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• 제20권2호
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• pp.95-100
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• 2003

This paper is for the investigation of the relationship between the geomagnetic disturbances and the relativistic electron events occurring at geosynchronous orbit. We have analyzed the electron fluxes of E > 2 MeV measured by GOES 10 satellite and the hourly Dst index for the period of April, 1999 to December, 2002. With the rigorous definition of the relativistic event, total 34 events were identified during the time period. Our statistical study showed that more than 50% of the total events occurred associated with weak (or sometimes virtually no) magnetic storms. And only ~ 20% of the events took place accompanied by a strong magnetic storm of $Dst_{min}$ < -100 nT. This result suggests that large geomagnetic storms may not be crucial for the occurrence of a relativistic event at geosynchronous orbit. We also found that there is no clear correlation between the maximum electron flux of an event and the associated minimum of Dst. Therefore any study on the physical mechanism (s) accounting for the relativistic events should take it into account that strong magnetic storms may not be necessarily required for the occurrence of a relativistic electron event at geosynchronous orbit.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 Asia Navigation Conference
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• pp.64-73
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• 2004

During the period of every summer to early autumn seasons, ships have been wrecked or grounded from effect of a typhoon in the waters around Korean Peninsular. Typhoon Rusa killed more than 100 people in September 2002. Super Typhoon Maemi passed southeast of South Korea in September 12-13, 2003, with gale winds blowing at a record 60 m/s and caused much ship groundings, collisions and sinkings over 3000 in dockyards, harbors and places of refuge. These are things that could have been prevented had there merely been prior warning. The aim of this study is to examine what effect these typhoons had on occurrence characteristics of the maritime accidents in South Korea. In this work, records of marine accidents caused by a typhoon are investigated for the period from 1962 to 2002. The distribution is also compared with the trajectories of typhoons, passed during the 1990-2003. It is shown that attack frequency of typhoon and number of marine accidents is the highest in August. We use the track data of Maemi such as central pressure, maximum sustained wind speed and area of each 15m/s and 25m/s winds as a case study to draw a map as a risk index.

• Journal of Astronomy and Space Sciences
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• 제35권3호
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• pp.151-161
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• 2018

Understanding solar influences on extreme weather is important. Insight into the causes of extreme weather events, including the solar-terrestrial connection, would allow better preparation for these events and help minimize the damage caused by disasters that threaten the human population. In this study, we examined category three, four, and five tropical cyclones that occurred in the western North Pacific Ocean from 1977 to 2016. We compared long-term trends in the positions of tropical cyclone occurrence and development with variations of the observed sunspot area, the solar North-South asymmetry, and the southern oscillation index (SOI). We found that tropical cyclones formed, had their maximum intensity, and terminated more northward in latitude and more westward in longitude over the period analyzed; they also became stronger during that period. It was found that tropical cyclones cannot be correlated or anti-correlated with the solar cycle. No evidence showing that properties (including positions of occurrence/development and other characteristics) of tropical cyclones are modulated by solar activity was found, at least not in terms of a spectral analysis using the wavelet transform method.