• 대기
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• 제21권2호
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• pp.143-149
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• 2011

A new multi-timescale analysis method, Ensemble Empirical Mode Decomposition (EEMD), is used to diagnose the variation of the MJO activity determined by 850hPa and 200hPa zonal winds from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis data for the 56-yr period from 1950 to 2005. The results show that MJO activity can be decomposed into 9 quasi-periodic oscillations and a trend. With each level of contribution of the quasi-periodic oscillation discussed, the bi-seasonal oscillation, the interannual oscillation and the trend of the MJO activity are the most prominent features. The trend increases almost linearly, so that prior to around 1978 the activity of the MJO is lower than that during the latter part. This may be related to the tropical sea surface temperature(SST). It is speculated that the interdecadal change in the MJO activity appeared in around 1978 is related to the warmer SST in the equatorial warm pool, especially over the Indian Ocean.

• 한국자원식물학회지
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• 제11권1호
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• pp.70-79
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• 1998

This study was conducted to understand the effects of weather and tapping date on yield and quality of lactree(Rhus verniciflua) sap yield showed a significant positive correlation with the minimum temperature of one day before sap collection at 1% level and with theminimum humidity of theday of sap collection at 5% level. However, the differences between the maximum and the minimum temperatures and humidities of the day of sap collection were negatively correlated with the sap yield at 5% level. Multiple regression analysis indicated that the minimum temperature of one day bofore sap collection and the minumum humidity of the day sap collection were important factors for increasing sap yield. The high sap yield of lactree by Japanese tapping method was recorded during mid-July and early August. Seasonal variation in lactree sap constituents was observed. The sap collected on 15th of August contained the highest urushiol content (68.3%) and the lowest water content resulting in high quality of lactree sap. By reversed-phase HPLC analysis, fove urushiol components were separated from each other depending on the number of doulbe bonds in the side-chain , and seaxonal variation of urushiol composition was noticed. The 3-C15 triene content fo the sap collected on 5th of July was the highest(77.56%) indicating the major component of urushiol which affects lactree sap quality.

• 환경생물
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• 제22권1호
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• pp.75-82
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• 2004

2000년부터 2002년까지 통영 바다목장 해역 5개 정점표층수와 저층수에서 종속영양세균의 개체수를 평판계수법으로 측정하여 종속영양세균군집의 계절별 변동추이를 비교 분석하고, 우점종을 선별하여 동정하였다. 7월과 8월의 하절기에 채수한 해수에는 봄 혹은 가을 및 겨울에 채수한 해수에 비하여 모든 정점에서 훨씬 더 많은 종속영양세균이 검출되었다. 저층수에 비하여 표층수에서 종속영양세균의 수가 더 많았으나 동절기(2001년 12월과 2002년 2월)에는 해수 온도가 낮으며 해수의 대류가 느려짐에 따라 부유물질이 저층에 축적되는 관계로 저층수의 종속영양세균의 수가 표층수의 경우 보다 오히려 더 많이 검출되었다 해수 내 종속영양세균의 수와 태풍의 빈도는 뚜렷한 상관관계를 보이지 않아 태풍의 빈도 이외에 태풍의 진로와 강도 및 태풍을 수반하는 집중 호우와 해수의 온도 변화가 종속영양세균의 수에 영향을 미치는 것으로 판단되었다. 통영 바다목장 해역의 종속영양세균의 우점종은 Pseudomonas fluorescens, Pseudomonas stutzeri, Acinetobucter lwoffii 및 Sphingomonas paucimobilis로 동정되었다.

• 대한교통학회지
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• 제19권6호
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• pp.65-73
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• 2001

교통량이 시간의 흐름과 관련이 있는 시계열 데이터라는 개념을 기초로 교통량 패턴을 시계열 분석을 사용하여 분해해 보고자 하였다. 교통량 패턴은 추세치(T)와 계절변동(S), 주기변동(C), 그리고 불규칙변동(I)으로 구분할 수 있었는데 본 연구에서는 불규칙변동을 기상요인을 통해 설명하려는 시도를 하였다. 왜냐하면 교통의 주체인 사람들 행태의 특성상 기상의 변화와 관련이 깊다고 판단을 내렸기 때문이었다. 기상요인으로는 일우량, 일조량, 풍속, 주야율 강설량, 기온 등 여러 가지가 있지만 교통량의 변화와 가장 관련이 깊다고 여겨지는 일우량과 최저기온을 이용하였다. 일단 시계열 성분을 분해하고 나면 이를 이용하여 AADT를 추정하게 되는데, 추정의 결과를 비교하기 위해 AADT 추정방법을 두 가지로 구분하였다. 즉, 기상요인을 사용했을 경우와 그렇지 않을 경우로 나누어 결과를 살펴보았다. 추정 결과를 비교하는 척도로는 RMSE와 U-test를 사용하였다. 결과를 보면 불규칙변동요인을 그대로 사용했을 때보다, 기상요인을 결합한 불규칙변동요인을 사용했을 때 더 추정력이 좋았다. 이것은 각 조사지점의 RMSE와 U-test값을 구한 후 그 지점의 AADT로 나누어 준 결과를 보고 알 수 있었다. 이 연구를 통해 우리는 불규칙변동요인 이용방법의 중요성에 대해 한번 더 생각해 보게 된다. 즉 그것을 설명하는 방법에 의해 기존보다 더 나은 모형을 얻을 수도 있다는 결론에 이르게 된다는 것이다.

• 한국농공학회논문집
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• 제54권6호
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• pp.39-44
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• 2012

Water supply capacity and operational capability in agricultural reservoirs are expressed differently in the limited storage due to seasonal and local variation of precipitation. Since agricultural water supply and demand basically assumes the uncertainty of hydrological phenomena, it is necessary to improve probabilistic approach for potential risk assessment of water supply capacity in reservoir for enhanced operational storage management. Here, it was introduced the irrigation vulnerability characteristic curves to represent the water supply capacity corresponding to probability distribution of the water demand from the paddy field and water supply in agricultural reservoir. Irrigation vulnerability probability was formulated using reliability analysis method based on water supply and demand probability distribution. The lower duration of irrigation vulnerability probability defined as the time period requiring intensive water management, and it will be considered to assessment tools as a risk mitigated water supply planning in decision making with a limited reservoir storage.

• 한국물환경학회지
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• 제24권3호
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• pp.317-327
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• 2008

This study developed the methodology to calculate the total daily maximum load (TMDL) using the instreamflow requirement because the previous TMDLs were too simple to easily achieve. Instreamflow requirement which was the average low flow ($Q_{275}$) in the previous planning cannot consider the seasonal variation of streamflow. Therefore, this study used the instreamflow requirement which is a maximum value among hydrologic drought flow ($Q_{355}$), and environmental flows for ecology and scenery. The environmental flows for ecology were calculated using Physical HABitat SIMulation system (PHABSIM) which can estimate the necessary flow for fish survival by life cycle. Using the proposed method, all monthly TMDLs of streams in the Anyangcheon were calculated for the application.

• Nuclear Engineering and Technology
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• 제49권2호
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• pp.380-386
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• 2017

Fennovoima's nuclear power plant, Hanhikivi 1, $Pyh{\ddot{a}}joki$, Finland, is currently in design phase, and its construction is scheduled to begin in 2018 and electricity production in 2024. The objective of this paper is to produce a preliminary list of safety-significant external event combinations including preliminary probability estimates, to be used in the probabilistic risk assessment of Hanhikivi 1 plant. Starting from the list of relevant single events, the relevant event combinations are identified based on seasonal variation, preconditions related to different events, and dependencies (fundamental and cascade type) between events. Using this method yields 30 relevant event combinations of two events for the Hanhikivi site. The preliminary probability of each combination is evaluated, and event combinations with extremely low probability are excluded from further analysis. Event combinations of three or more events are identified by adding possible events to the remaining combinations of two events. Finally, 10 relevant combinations of two events and three relevant combinations of three events remain. The results shall be considered preliminary and will be updated after evaluating more detailed effects of different events on plant safety.

• Journal of Plant Biology
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• 제23권2호
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• pp.61-67
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• 1980

As a part of the environmental base line survey of the Onsan Industrial Base, Korea, marine algal communities were investigated using the quadrat method in Onsan-myon on the east coast of Korea from March to December of 1978. It was learned that the representative dominat species along the coast in the Onsan area throughout the year are Ulva pertusa, Pachymeniopsis elliptica, and Sargassum thunbergii. Both the number of algal species occurring in the quadrat (50$\times$50cm) and the total coverage were higher in March and September than in June and December. A total of 94 species (1 blue-green, 16 green, 25 brown, and 52 red algae) of marine algae was identified in this study.

• Journal of the Korean Data and Information Science Society
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• 제19권4호
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• pp.1201-1210
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• 2008

The goal of this paper is to investigate the trend of stream quality and the quality of water in Nakdong river by the method of factor analysis. It used the fourteen different monthly time series data such as pH, BOD, COD, SS, TN and etc. of the thirty four of Nakdong River measurement points from Jan. 1998 to Dec. 2006. The result of factor analysis is that the factor 1 results from organic water pollution is occupied 29.288% such as BOD, COD, TN and EC, and the factor 2 explained from sewage and a seasonal variation is occupied 16.467% such as SS.

• Journal of Preventive Medicine and Public Health
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• 제19권2호
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• pp.293-306
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• 1986

A Health Interview Survey at Chuncheon city was conducted to assess level of illness by stratified random sampling method. Sample size was 6,007 and the prevalence of illness in period of 15 days was studied. 1) Prevalence rate of illness among Chuncheon citizen was 20.8 percent, and that of acute condition was 10.8 percent and chronic condition, 10.0 percent. 2) There was significant difference in prevalence rate by sex, especially the prevalence rate of chronic illness. 3) High positive correlation was noted between aging and prevalence rate of chronic illness. But negative correlation was noted in case of acute illness. 4) Multiple regression analysis on morbid state by socioeconomic variables was not seen to be appropriate for this survey, especially the analysis of acute illness. 5) Estimation of anual prevalence rate could not be possible because of seasonal variation of disease prevalence.